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  • Munksgaard International Publishers  (82)
  • 1990-1994  (82)
  • 1970-1974
  • 1955-1959
  • 1991  (76)
  • 1990  (6)
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  • 1990-1994  (82)
  • 1970-1974
  • 1955-1959
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  • 1
    Electronic Resource
    Electronic Resource
    Copenhagen : Munksgaard International Publishers
    ISSN: 1600-0501
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The present paper is part of a comprehensive study of dental conditions and attitudes in a Swedish county population aged 45–69 years. A questionnaire was mailed to 3000 randomly-sampled individuals. The response rate was 79.4% Part of the questionnaire contained questions about subjective need for implant treatment. The subjects were informed of the clinical procedures as well as of the fees for implant treatment in the Swedish insurance system. The subjects wearing removable dentures were asked if. instead of their removable denture(s), they wanted dental implants if such treatment was possible. Of those wearing removable partial dentures, 23% answered “yes”. The corresponding figure for subjects totally edentulous in one jaw was 17%; for subjects totally edentulous in both jaws 8%percnt;. The individuals who had reported missing teeth not replaced were asked if they wanted their missing teeth replaced by dental implants if such treatment were possible. The % answering “yes” was 21%. The subjects with all teeth remaining were hypothetically asked what kind of treatment they wanted if they would lose 1 or 2 of their teeth. The answer “dental implant” was given by 51%. Thus, subjective need for dental implants tended to decrease with poorer dental conditions. The major reason for not wanting dental implants was satisfaction with present dental conditions. Cost for treatment had some importance. while environmental and psychological factors showed only very limited influence.
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  • 2
    ISSN: 1600-0501
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: This investigation is the result of a multicenter research project between the Catholic University of Leuven and the University of Madrid with the purpose of studying histometrically and ultrastructurally periimplant marginal tissue reactions in medium-term Brånemark implants. 12 patients were selected and distributed according to predefined clinical and radiological parameters into a periimplant infection group (A) and a non-periimplant infection group (B). Biopsies were taken from these patients and analyzed by means of microscopy (LM), histometry (HM) and transmision electron microscopy (TEM). With LM group A showed pathological features consistent with an advanced gingivitis lesion, while group B showed signs of healthy gingiva in the connective tissue and vauolae formation in the epithelium. With HM, group A showed significantly higher transmigration of inflammatory cells in the epithelium than group B. In the connective tissue, group A showed a higher % of inflammatory infiltrate with significantly higher numbers of plasma cells and mononuclear cells than group B. With TEM, group A showed an ultrastructural picture consistent with plaque-induced periodontitis, while group B showed a rather healthy connective tissue and vacuolae formation in the epithelium. These results suggest that supra-crestal marginal tissues around osseointegrated implants react to plaque bacteria similarly to periodontal tissues around teeth by chronic inflammation.
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  • 3
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: Acute responses to 65 min exposures to environmental tobacco smoke (ETS) were tested in 24 healthy non-asthmatic nonsmokers and 16 asthmatic nonsmokers, using an environmental chamber. Each subject was exposed to air (sham), and machine-generated cigarette smoke containing 17 ppm and 31 ppm carbon monoxide (CO). Nonasthmatic subjects exercised intermittently (mean respiratory minute volume (V̊E) of 44 l/min during each of two 15–min exercise bouts); asthmatic subjects remained at rest. After completion of the exposure, subjects made a 0–5 rating of the severity of symptoms, as well as rating the overall severity of exposure on a 0–100 scale. Both symptoms and exposure severity rating were significantly related to CO concentrations. Ratings for a given ETS exposure tended to be higher for asthmatic than for nonasthmatic subjects. Overall exposure severity rating was significantly (p 〈 0.05) related to four symptom scores for the asthmatics and three for the nonasthmatic subjects. Symptoms common to both groups included unpleasant odour, and nasal discharge; shortness of breath was unique for nonasthmatics and eye irritation for asthmatk subjects. Although the nonasthmatic subjects were exercising intermittently, and thus received both a higher respiratory exposure (calculated from a CO-based index of ETS concentration, V̊E, and time) and biological exposure (calculated independently using a rebreathing estimate of the increment in carboxyhemoglobin level), the asthmatic subjects appeared to be more adversely affected by the ETS exposures in terms of their subjective responses.
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 1 (1991), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: Thermal comfort measurements were taken in 17 enterprises at 129 work sites in shops, stores and offices. The measurements included air temperature, air velocity, relative humidity and radiant temperature asymmetry according to ISO 7726 and ISO 7730 standards. The workers also answered a questionnaire dealing with thermal comfort. Predicted mean vote (PMV) and the percentages of workers complaining of draught (“percentage dissatisfied”, PD) were determined and compared with the workers' assessments of thermal conditions. The estimations of air temperature were always too low, and the estimated PMV indicated that the thermal environment was too warm. The calculated PMVs were usually lower than the estimated ones. Most of the workers complained of draught, even though, according to the PD index, fewer than 17% of the workers should have felt discomfort due to draught. The radiant temperature asymmetry was always small and did not explain complaints of draught on the basis of the reference value. Judged by the present reference values, and the measurement of the thermal environment, the workers overestimated the sensation of thermal discomfort.
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  • 5
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: The purpose of this study was to evaluate whether asthmatic reactions and changes in tear film quality could be provoked by exposing subjects to emissions from building materials in climate chambers. Twenty asthmatics and 5 healthy controls were exposed to (1) gypsum board hung with waterborne painted wallpaper; (2) rubber floor covering; (3) nylon carpet with rubber mat; (4) particle board coated with acid-curing paint; and (5) no test materials in climate chambers for 6 h. Participants recorded symptoms by filling in questionnaires, and clinical data were evaluated by lung function measurements at intervals of 30 min to 1h, and external eye examinations before and after exposure (appearance of foam at eyelid, semi-quantitative measurements of precorneal superficial lipid layer, break-up time and epithelial damage). There was agreement between a trained panel's evaluation of perceived air quality and the participants' opinion of indoor air quality. No correlation was found between lung function measurements and exposure to the materials. However, for all materials, statistically significant changes in tear film quality were observed to varying degrees. Lipophilic Volatile Organic Compounds (VOCs) may destabilize the lipid multilayer of the tear fluid, and this mechanism is suggested to be at least partly responsible for eye irritation.
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  • 6
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: The emission of volatile organic compounds (VOCs) from five different waterborne paints was measured in small climatic chambers under standard conditions over a one-year period. The aims of the study were to evaluate the time emission profiles and to develop methods for comparison of different paints. The paints were applied to tin-plated steel sheets. VOCs were sampled on Tenax TA and analysed by thermal desorption and gas chromatography. The chamber concentrations increased rapidly during the first few hours and then decreased as the emission rates dropped. A model expression including an exponentially decreasing emission rate of the paint film, the air exchange rate, and a normalization of the film thickness was fitted to the concentration versus time data. The time required to reach a given emission rate was estimated and found suitable for comparison of the emission of VOCs from the paints. It was found that data sampled within three weeks or less may be sufficient to predict the emission of VOCs up to one year. Reduction of long-term emissions may be achieved most efficiently by (1) substituting a more -volatile VOC whose emission is controlled by evaporation for a less volatile VOC characterized by diffusion-controlled emission and (2) reducing the paint film thickness rather than reducing the initial VOC content of the paint.
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 1 (1991), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 1 (1991), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: A numerical model has been developed to investigate the contaminant removal and air freshness in a ventilated two-zone enclosure. The average contaminants and the distributions of air age in each zone under variable positions of door, supply and exhaust are compared. The correlation between the average contaminants and each of the main parameters, such as door location, supply and exhaust positions etc., are presented, and the average air ages in both zones are illustrated against door position. It is found that the average air age in the upstream zone is less affected by the door position than that in the downstream zone, and that the door position near the side-walls seems to give better air circulation. It is also concluded that the supply and door positions affect the concentration in the upstream zone significantly, while the exhaust location does not seem to influence the average concentration in either the upstream or the downstream zone.
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 1 (1991), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: The Zolder case was one of the six case studies on mould problems and sulface condensation, initiated within the International Energy Agency (IEA) Annex 14 on “Condensation and Energy”. This project, a joint research effort of Belgium, the Federal Republic of Germany, Italy, the Netherlands and the United Kingdom, was completed in March 1990.Complex relations bemeen mould, surface condensation, energy caservation and parameters such as the outdoor climate, the thermal quality of the building, the ventilation and the occupants' behaviour are explained, followed by an analysis of the Zolder-Lindeman case. This illustrates the extent to which mould may deteriorate the livability of a social housing estate. On three houses, different mitigation measures were evaluated before and after implementation: loft space insulation, inside insulation, double glazing outside insulation, natural ventilation, and demand controlled ventilation.The results for one of the three show that the severe mould problems resulted from the cambination of poor overall insulation quality and the impossibility of ventilating properly. A thermal retrofit, together with the installation of a natural ventilation system, proved to be successful.
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  • 10
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 1 (1991), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: This paper describes tests of thermal comfort and air distribution performance of two relatively new occupant-controlled localized ventilation (also called task ventilation) systems. The first is a raisd-floor distribution system providing air through grilles in the floor panels, and the second is a desk-mounted unit supplying conditioned air at desktop level. The tests were performed in a new controlled environment chamber (CEC) having unique capabilities for detailed studies of space conditioning and thermal comfort in office environments. Measurements were made in a mockup of a typical partitioned open-plan office, and the resulting temperature and air velocity distributions are reported for a variety of system- and locally controlled conditions. Comfort model predictions are presented to describe the degree of environmental control and range of occupant comfort levels produced in the workstations. The results are also compared to those produced by a conventional ceiling supply system.The tests investigated the effects of supply volume, supply location, supply vent orientation, supply/return temperature difference, heat load density, and workstation size and layout. Temperature differences in the range of 1–2.5°C were observed between adjacent workstations, and local air velocities in the vicinity of outlets could exceed 3 m/s. Such wide-ranging values could violate existing comfort standards (ASHRAE, 1981; ISO, 1984), if strictly interpreted. However since these systems put the local thermal conditions within the workstations under the direct control of their occupants, it is recommended that the standards grant exceptions to such systems.
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  • 11
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 1 (1991), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: The main airflow and contaminant paths or the spatial distribution of the age of air (or contaminant) in a room are of great interest in estimating venrilation efficiency. A simple meusurement method is presented which consists of injecting one or more tracer gases at locations of interest and analysing the concentration at several other locations, carefully chosen for best accuracy.Response functions can be fitted to these measurements, which are the age of the tracers or of the air or the concentration of the tracers as a function of the location. The salient paths, such as the dead zones, are also determined from these functions.The paper presents the method, its application and validation in a well controlled test room.
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  • 12
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: The influence of personal activity sources on exposure to indoor contaminants is defined and demonstrated using data from occupational and residential studies. The ratios of measurements from personal exposure monitors to those made by microenvironmental exposure monitors are summarized to be typically 3 to 10 for occupational settings and 1.2 to 3.3 for residential settings. The ratios are shown to be lognormally distributed, and dependent primarily on the proximity of the source to the receptors. Current models are reviewed for possible application to the prediction of indoor concentration gradients and future model development and validation studies are suggested.
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  • 13
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 1 (1991), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: Two families of macroscopic adsorption models are formulated, based on fundamental principles of adsorption science and technology, that may be used for macroscopic (e.g., whole-building) contaminant dispersal analysis. The first family of adsorption models – the Equilibrium Adsorption (EA) Models – are based upon the simple requirement of adsorption equilibrium between adsorbent and room air. The second family – the Boundary Layer Diffusion Controlled Adsorption (BLDC) Models – add to the equilibrium requirement a boundary layer model for diffusion of the adsorbate from the room air to the adsorbent surface. Two members of each of these families are explicitly discussed, one based on the linear adsorption isotherm model and the other on the Langmuir isotherm model. The linear variants of each family are applied to model the adsorption dynamics of formaldehyde in gypsum wall board and compared to measured data. These applications and a more general consideration of the dynamic character of adsorption provided by these models indicate that simple physical adsorption and desorption transport processes h e the potential to significantly affect the dispersal of contaminants in buildings.
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  • 14
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: The paper evaluates ocular manifestations as reported in two different questionnaires completed within one to Two weeks by 164 office workers in four town halls in Copenhagen. Among 14 previously investigated, these town halls constitute the two with the highest and the two with the lowest prevalence of the Sick Building Syndrome (defined as mucous membrane complaints such as eye, nose or throat irritation, and general symptoms such as headaches or fatigue several times a week). There was a highly significant rank correlation in each of the four town halls between the frequency of self-reported ocular manifestations in the two questionnaires. Furthermore, the eye complaints reported in both questionnaires were significantly correlated with an objective measure for eye dryness, investigated using a biomicroscope. By combining the two questionnaires it was possible to define subgroups using both frequency of eye complaints and consistency of reporting in the two questionnaires. The subgroup of 107 subjects with consistency in the frequency of their eye complaints in the two questionnaires showed a significantly higher correlation with the objective index than did the subjects with inconsistent reporting. Furthermore, with increased frequency of complaints and consistency of reporting, not only the prevalence of microscopically determined eye dryness, but also the number of up to 7 different eye symptoms per subject increased, and an increased percentage of these symptoms was found to be related to sensory reactions in the common chemical sense, which earlier has been postulated to be involved in the Sick Building Syndrome. In conclusion, the study shows that data from two different questionnaires on self-reported ocular manifestations associated with the Sick Building Syndrome are reproducible and associated with objective dryness in the eyes.
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  • 15
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: Volatile organic compounds (VOC) in office buildings originate from multiple sources, such as outdoor air, building materials., occupants, office supplies, and office equipment. Many of the VOC found in office buildings are also present in environmental tobacco smoke (ETS), e.g., benzene, toluene, formaldehyde. Measurements made to date in office buildings have been interpreted by some to imply that the contributions of ETS to VOC exposures in office buildings are small. We have made a first order estimate of the contributions of ETS to VOC concentrations based on the VOC content of ETS and a time-dependent mass-balance model. Four different ventilation-infiltration scenarios were modelled for a typical office building.The results indicate that ETS can contribute significantly to total indoor levels of VOC in office buildings, even under moderate ventilation conditions. Ranges of concentrations for three of the four modelled scenarios substantially overlapped measured ranges of the compounds in office buildings. Average daytime concentrations of benzene from ETS, for example, for three of the four modelled scenarios, ranged from 2.7 to 6.2 μg m−3, compared to reported measurements of 1.4 to 8.1 μg m−3 for four office buildings. Under a “worst reasonable” case scenario, the average modelled ETS-contributed concentration of benzene was 33.9 μg m−3 for a 40-hour work week.
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  • 16
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 1 (1991), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: We have developed a new air sampler for collecting parriculate and gas phase polycyclic aromatic compounds (PAC). This sampler was designed to collect a 25 m3 volume of air at a constant sampling rate of 34 l/min over a 12-hour sampling penod. The 25 m3 sample volume is necessary to achieve the desired nglm3 detection limit for PAC. The 34 l/min sampling rate is estimated to cause less than a 5% reduction in the indoor contaminant concentrations. The sampler pump is a I/4 horsepower vacuum pump in an acoustically shielded fan-cooled enclosure and is relatively quiet. The pump draws air through a 47 mm teflon impregnated glass fibre filter for collection of particulate-phase PAC followed by a cartridge containing XAD-4 resin in front and back sections (2.5 g each) for collection of gas-phase PAC. In a pilot field study the mean breakthrough from the front sorbent section to the back section was less than 1% for each of 14 species of gas phase PAC except biphenyl which had a mean breakthrough of 3.7%. The pressure drop increase across the filter is linear up to a loading of 6 mg and causes less than a 10% reduction in the sample flow rate. The sampler was successfully demonstrated in a pilot field test with air temperatures as high as 30°C.
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  • 17
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 1 (1991), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: We model radon entry into basements using a previously developed three-dimensional steady-state finite difference model that has been modified in the following ways: first, cylindrical coordinates are used to take advantage of the symmetry of the problem in the horizontal plane, thereby increasing resolution and computing eficiency without signifiant loss of generality; second, the configuration of the basement has been made m e realistic by incorporating the concrete fmtm which sup ports the basement walls and floor; third, a quadratic relationship between the pressure and flow in the L-shaped gap between slab, footer, and wall has been employed; and fourth, the natural convection of the soil gas which follows from the heating of the basement in winter has been taken into account. The temperature field in the soil is determined fiom the equation of energy consmation, using the basement, surface, and deep-soil temperatures as boundary conditions. The pressure field is determined from Darcy's law and the equation of mass conservation (continuity), assuming that there is nofIow across any boundary except the soil surface (atmospheric pressure) and the opening in the basement shell (fixed pressure), Since the energy conservation equation includes both heat advection and conduction, the temperature and pressure equations must be coupled. After the pressure and temperature fields have been obtained, the velocity field is found fiom Darcy's h. Finally, the radon concentration field is found from the equation of mass-transport, assuming that diffusive entry through openings may be neglected. The convective radon entry rate through the opening or openings is then calculated. In this paper we describe the modified model, compare the predicted radon entry rates with and without the consideration of thermal convection, and compare the predicted rates with rates determined from data from seven houses in the Spokane River valley of Washington and Idaho. Although the predicted rate is much lower than the mean of the rates determined from measurements, er-TOTS in the measurement of soil permeability and variations in the permeability of the area immediately under the basement slab, which has a signifiant influence on the pressure field, can account for the range of entry rates inferredfiom the data.
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  • 18
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 1 (1991), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: Airborne pollutants can cause failures in switching and computing equipment. This paper focuses on a subset of such pollutants - airborne fine panicles (〈 2.5 μm diameter). It begins by examining the extent to which different improvements in heating, ventilating and air conditioning (HVAC) systems reduce indoor concentrations of fine particles. For each modification, the consequent reduction in soiling rate is derived. The concomitant increase in operating costs is also calculated. These costs are then compared with the costs of failures in telephone switching offices, leading to estimates of failure rate reductions that would make improvements cost-effective. Finally, the reduction in failures required to offset the costs of the improvements are compared with documented differences in failure rates between unimproved and improved environments. This study suggests that, in many telephone switching offices, the added operating costs associated with more efficient building filters and continuous fan operation are more than offset by reductions in failure rates.
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  • 19
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 1 (1991), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: This publication summarizes field investigations and controlled experiments on the relation between low levels of indoor air pollution with volatile organic compounds (VOC) and human health and comfort. The Henle-Kock criteria from epidemiology are revised for the dose-response relation between VOC's and health as comfort effects and existing evidence for each criterion are discussed. A biological model for human responses is suggested, based on three mechanisms: sensory perception of the environment, weak inflammatory reactions, and environmental stress reactions. Further, the TVOC-indicator concept for exposure is discussed. The conclusion is that no experimental or field data contradict the proposed causality. On the contrary, evidence supports the suggested causality. The biological model, however, is not yet based on acceptable measures of the variables for exposures, co-variables or health effects. A tentative guideline for VOC's in non-industrial indoor environments is suggested. The no-effect level seems to be about 0.2 mg/m3. A multi-factorial exposure range may exist between 0.2 and 3 mg/m3. Above 3 mg/m3 discomfort is expected.
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  • 20
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: Monitoring of human reactions to the emission of formaldehyde and volatile organic compounds (VOC) from four commonly used building materials was carried out. The building materials were: a painted gypsum board, a rubber floor, a nylon carpet, and a particle board with an acid-curing paint. The exposures were performed in climate chambers. The air quality was quantified on the decipol scale by a trained panel, measurements of formaldehyde and VOC being performed simultaneously. The irritating potency of the materials was measured by a mouse bioassay. The VOC measurements showed several malodorants and irritants. Some abundant VOC identified in the head-space analyses were absent in the climate chamber air. The rubber floor and the nylon carpet exhibited a marked increase in decipols compatible with a number of odorous VOC identified in the air. A high formaldehyde concentration (minimum 743μg/m3) was measured for the particle board coated with an acid-curing paint. This was not reflected by a corresponding relatively high decipol value but a long-lasting irritating potency was observed in the mouse bioassay. TVOC sampled on Tenax and expressed in mass per volume as well as in molar concentration, and decipol evaluation both have limitations and should be used with caution as indicators of (perceived) indoor air quality. Eye irritation expressed by means of the eye index reflecting the tear film quality index (comprised of break-up time, foam formation, thickness of the precorneal lipid layer of the tear film, and epithelial damage) was found to be insensitive to formaldehyde and a VOC mixture but sensitive to TVOC concentrations of 1–2 mg/m3. Lipophilic VOC may be the cause of reduced tear film quality by destabilization of the lipid multilayer of the tear film.
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  • 21
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: The aim of the study was to compare the results of a self-administered questionnaire, designed to estimate the prevalence of the sick building syndrome, with an independent medical interview and clinical opinion. Six buildings were chosen for study from a sample of 47 with known measurements of the building symptom index. One building with a high and one with a low score was selected from each of three ventilation classes (natural ventilation, air-conditioning with induction units and air-conditioning with variable air volume systems). A stratified random sample of 160 workers in these buildings was studied. Each received, in random order, a self-administered questionnaire, and a medical opinion based on a free medical history. The doctor had no access to the self-administered questionnaire at the time. The average number of work-related symptoms per worker (the building symptom index), which is used to compare one building with another, showed a good agreement between the two methods. There were, however, consistent differences between the two assessments in individual symptoms. The self-administered questionnaire produced a higher prevalence of work-re-lated runny nose and flu-like symptoms, which were often regarded as being due to infections in the medical opinion. In individuals, work-related symptoms on the self-administered questionnaire were validated by the medical opinion in over 75% of cases for eye and throat symptoms, lethargy and headache. Only 31% of work-related runny nose and 21% of work-related flu-like symptoms were thought by the medical opinion to be work-related. The medical opinion identified an extra 5% of work-related symptoms that were missed on the self-administered questionnaire. The self-administered questionnaire therefore produced a satisfactory estimate of the building symptom index, removing the potential bias of an interviewer. The questions on ninny nose and flu-like symptoms would be improved by including only those that occurred more frequently. The building symptom index was calculated for the six buildings twice, with separate random samples of workers completing the questionnaire two years apart. The buildings were ranked in the same order (for the building symptom index) on both occasions, again confirming the validity of the self-administered questionnaire.
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  • 22
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 1 (1991), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: Concern for the health risk of occupants in buildings containing asbestos fireproofing, acoustic materials or lagging, among other products, has led to several investigations of airborne asbestos concentrations in buildings and exposure assessments of occupants and maintenance personnel. The purpose of this paper is to summarize these results, to place in perspective exposure to occupants and maintenance personnel, and to estimate risks based on these exposures. Regulatory implications of these results are discussed. It is concluded that asbestos-in-air measurements carried out with the most appropriate methods in buildings with damaged or undamaged asbestos-containing materials consistently show extremely low concentrations comparable to those measured outdoors for fibers greater than 5 μm in length. Risks to occupants in such buildings are correspondingly very low. Potential exposures are higher to those performing building maintenance procedures that may disturb the asbestos-containing materials. Operations and maintenance procedures are effective in protecting maintenance personnel through engineering controls, work practices and personal protective devices, which are used to a greater or lesser extent depending on the specific activity.
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  • 23
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 1 (1991), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: Field measurements of 21 volatile organic compounds (VOC) using diffusive samplers, formaldehyde, temperature, and humidity were performed from the time of building completion throughout the following one-year period in two new semi-detached twin apartments. One of these was occupied after six weeks. Headspace analyses from all building materials and products showed 120 different VOC. Formaldehyde concentrations were strongly seasonally dependent in the vacant apartment and increased to above 400 μg/m3 during the warm season. The formaldehyde concentration generally decreased in the occupied apartment but increased again during the fall season. VOC originating from building materials generally showed a decrease in emission, but strong seasonal variations were observed. It was shown that human activity introduces several VOC to the indoor environment. Storage of motorcycle parts in the crawl space of the occupied apartment resulted in migration and an infiltration of benzene and toluene into the apartment above and probably to a delayed peak concentration in the twin vacant apartment. Similarly, large VOC increases in one apartment were reflected by a later increase of the same VOC in the twin apartment. Hexanal increased during the warm season. TVOC, as the sum of 21 VOC, was generally approximately 50 % higher in the occupied apartment during the cold season. The results indicate the difficulties in interpreting long-term measurements. The “flushing period” recommended for this type of building has been estimated to be about 130 days.
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  • 24
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 1 (1991), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: A model based on heat diffusion through the skin is developed for the dynamic response of cutaneous thermo-receptors to temperature stimuli at the skin surface. It is applied to various neurophysiological experiments with good results. The model is then extended to sensation and a set of psychophysical experiments on human subjects is examined and compared with the model predictions. Altogether, in terms of both the neurophysiological response and the sensation response, this model gives good agreement with the experiments.
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  • 25
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: The purpose of the study was to evaluate the occurrence of symptoms and the perception of poor indoor air quality among the occupants of houses and apartments with different ventilation systems. The study population consisted of the 473 occupants of 242 dwellings in the Helsinki metropolitan area who responded to a self-administered questionnaire (response rate 93.1%) after a two-week period of indoor air quality measurements. The symptoms of interest were those often related to poor indoor air quality including dryness or itching of the skin; dryness, irritation or itching of the eyes; nasal congestion (“blocked nose”) nasal dry-ness; nasal discharge (“runny nose”); sneezing; cough; breathlessness; headache or migraine; and lethargy, weakness or nausea. Perception of coldness; warm-ness; draught; dryness; stuffiness; and sufficiency of air exchange was also requested. The age-standardized period prevalences of the symptoms and complaints were systematically more common among the occupants of the apartments than those of the houses. The occupants of the houses with natural ventilation seemed to have more symptoms and complaints than those with balanced ventilation. However, in the apartments with balanced ventilation the occupants reported, in general, more symptoms and complaints than those with natural ventilation.
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  • 26
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 1 (1991), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: One of the objectives of EPA's indoor air quality (IAQ) program is to provide guidance on the impact of indoor sources on IAQ. A computer model, EXPOSURE, was developed to assist in this effort. EXPOSURE calculates pollutant concentration as a function of time for each room of the building. EXPOSURE includes effects of sources, sinks, room-to-room air movement, and air exchange with the outdoors. Several experiments designed to evaluate the impact of indoor sources on IAQ are described. Measured concentrations are compared with concentrations predicted by an IAQ model. The measured concentrations are in excellent agreement with the predictions. The model predictions and the experimental data demonstrate the importance of sinks in determining long-term IAQ.
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  • 27
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 1 (1991), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: It is well known that the inhabitants of dwellings use the room heating and ventilation to build up their own individual climatic zone in which they feel comfortable. To date individual measurements have been conducted to investigate these climatic zones, or line charts have been drawn up with a thermohygrograph in long-duration tests.Compared with the form of presentation used previously, the possibilities for evaluation have been substantially improved by the use of measured data-recording installations for the long-term investigation and presentation of results in the form of dots (temperature/humidity value pairs) in an h,x-diagram. The h,x-diagram is a type of psychrometric chart which is widely used in Germany. The advantage of this chart is that all thermodynamic properties of moist air can be determined without calculation. The dry bulb temperature, the wet bulb temperature, the dew point, the relative humidity, the humidity ratio, the specific enthalpy and the specific volume of moist air can be read directly from the diagram.
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  • 28
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 1 (1991), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: The indoor air quality in several types of dwellings that were renovated to save energy for spatial heating has been investigated. Concentrations of pollutants were monitored in three rooms of inhabited houses. Data of the outside air and ventilation and infiltration were also collected. Relationships were established between observed concentrations and ventilation. In some cases concentrations show a good relationship with the calculated air change rate, in other cases this relationship was poor or absent.Elevated levels of pollutants could be related to sources in most cases. The ventilation behavior of the inhabitants has a major influence on the concentrations.From this and other studies it can be concluded that, in general, making dwellings more airtight leads to higher concentrations of pollutants. Deviations from health-related guidelines then become more likely.
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  • 29
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 1 (1991), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: Mechanical ventalation system performance involves the provision of adequate amuunts of outdoor air, uniform distribution of ventilation air within the occupied space, and the maintenance of thermal comfort. Standard measurement techniques exist to evaluate thermal comfort and air change rates in mechanically ventilated buildings; procedures to evaluate air distribution or ventilation effectiveness in the field are still being developed. This paper presents measuremetlts of air change rates and ventilation effectivenes in an office/library building in Washington, DC. The tracer gas decay technique was used to measure whole building air change rates. The air change rates during the measurement period were essentially constant at about 0.8 air changes per hour, somewhat below the design specification and above the minimum recmmmded in ASHRAE Standard 62-1989. Ventilation effectiveness was investigated at several locations within the building through the measurement of local tracer gas decay rate and mean local age of air. The ventilation effectiveness measurements serve as an investigation of the applicability of the m e a s u r r n procedures employed, providing insight into the measurement issue of establishing initial conditions, the spatial variation in test results within a building, and the repeatabildy between tests. The results of the ventilation effectiveness meusurements are consistent with good distrhtion of the outdoor air by the ventilation system and good mixing within the occupied space.
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  • 30
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 1 (1991), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: We studied the performance of a task ventilation system that permits occupants to control the flow rate and direction of air supplied to their work space through four floor-mounted supply grill. Air exited the room through a ceding-mounted return grill. To study air-flow patterns, we measured the age of air at multiple locations using a tracer gas stepup. To study the intra-room transport of tobacco smoke particles, cigarettes were smoked mechanically in one workstation and particle concentrations were measured at multiple locations. Our major findings were as follows: (1) deviations from uniform age of air, and uniform particle concentration, were generally less than 30 percent; (2)some supply air short-circuits to the return grill when directed toward the return with high velocity; (3) low supply velocities resulted in a floor-to-ceiling displacement flow; (4) directing the supply air toward the occupant, of partially toward the occupant, typically yielded an age of air at the occupant's breathing level that was 15 to 25 percent lower than the age at other breathing-level locations; (5) with low supply velocities und air directed toward the occupants, tobacco smoke particle concentrations in a ventilated non-smoking workstation were 50 percent of the chamber-average concentration.
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  • 31
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 1 (1991), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: This paper describes the techniques used within the ESPR/〉 system to represent and solve the heat and mass conservation equations relation to combined building and plant systems. In Particular, it describes the equation-sets used to represent inter-zonal (building) and inter-component (plant) fluid flow and the method used for the integration of the non-linear heat and muss frow equations. By means of a case study, the application in a real design context is demonstrated.
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  • 32
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 1 (1991), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: The interaction of indoor air pollutants with interior surfaces (i.e., sinks) is a well known, but poorly understood, phenomenon. Studies have shown that re-emissions of adsorbed organic vapours can contribute to elevated concentrations of organics in indoor environments. Research is being conducted in small environmental test chambers to develop data for predicting sink behaviour. This paper reports on the development of sink models based on fundamental mass transfer theory. The results of experiments conducted to determine the magnitude and rate of adsorption and desorption of vapour phase organic compounds for several materials are presented. Five materials were evaluated: carpet, painted wallboard, ceiling tile, window glass, and upholstery. Two organic compounds were tested with each material: tetrachloroethylene (a common cleaning solvent) and ethylbenzene (a common constituent of petroleum-based solvents widely used in consumer products). The results of the experimental work are presented showing the relevant sink effect parameters for each material tested and comparing the sorptive behaviour of the two organic compounds evaluated. An indoor air quality (IAQ) model was modified to incorporate adsorption and desorption sink rates. The model was used to predict the temporal history of the concentration of total vapour phase organics in a test house after application of a wood finishing product. The predicted results are presented and compared to measured values. Suggestions for further research on indoor sinks are presented.
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  • 33
    Electronic Resource
    Electronic Resource
    Copenhagen : Munksgaard International Publishers
    ISSN: 1600-0501
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: This study involved 108 patients (age 38–82 years) rehabilitated with overdentures in the lower jaw supported by 2 endosseous screw-shaped implants. At each follow-up visit, the clinical attachment level (PAL) around the implants was assessed with a Merrit-B probe or a constant force electronic probe, Peri-probe, and biannually parallel long-cone radiographs were taken to locate the marginal bone level. These data were used to examine the relationship between bone and attachment level estimations around implants. As a mean, bone level was scored 1.4 mm apically of PAL and this difference remained constant with time. The Pearson correlation coefficient between bone level and PAL, for mesial and distal sites, was 0.67 and 0.61 for the Merrit-B probe, and 0.76 and 0.65, respectively for the Peri-probe. The highest correlations were obtained for sites with a healthy gingiva or in absence of intra-bony craters. Duplicate PAL registrations showed a standard deviation for the intra-examiner variability of 0.37 (Peri-probe) or 0.40 mm (Merrit-B probe) with more than 90% of the variation within 0.5 mm. The mean difference in PAL between Merrit-B probe or Peri-probe was 0.05 mm. It was concluded that the clinical attachment level determination is a reliable indicator for bone level around implants with a moderate healthy gingiva.
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  • 34
    Electronic Resource
    Electronic Resource
    Copenhagen : Munksgaard International Publishers
    ISSN: 1600-0501
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The purpose of this paper is to report the outcome of 1097 consecutively implanted endosteal implants (Brånemark®) into 303 jaws, between September 1983 and May 1990. All implants were placed using the prescribed technique suggested by manufacturer, and were restored either with fixed or removable prosthesis. Alveolar bone resorption (quantity) was scored from lesser to greater degree by assigning a value of l–5 to each jaw, and jaw anatomy was scored from l–l, based on decreasing cortical and cancellous bone quality. The data were separated into fixed and removable prosthesis and analyzed to determine the correlation between success and the scored resorption and jaw anatomy, as well as implant position. Assessment demonstrated a maxillary success rate of 93.4% and a mandibular success rate of 97.2% over a 36-month period (mean). Results of correlations of success with jaw anatomy for both fixed and removable prosthesis revealed that bone quality 4 exhibited the greatest failure rate. Preoperative resorption values (1-S) had little effect on failure, and quality appears to influence failure more than I quantity.
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  • 35
    ISSN: 1600-0501
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The presence of certain glycosaminoglycans in peri-implant sulcus fluid may be an effective means of monitoring changes in bone metabolic activity following initial loading of implant abutments. This study has investigated levels of chondroitin 4 sulphate and hyaluronan in peri-implant sulcus fluid from titanium osseointegrated implants following initial abutment placement and exposure to masticatory stresses. Abutments were placed after a 3-month osseointegration period post-initial surgical placement of the interosseous stage. 10 edentulous patients, each with 5 mandibular implants were reviewed at 2, 4, 6 and 8 days after abutment placement. Clinical details were assessed and recorded and sulcus fluid collected in microcapillary tubes for a 5-min period for each abutment. Levels of glycosaminoglycans were assessed using cellulose acetate electrophoresis and densitometric scanning of alcian blue stained strips against known glycosaminoglycan standards. Maximum levels of sulcus fluid (0.3–1.25 /5 min) were evident at 4 days with a decrease towards 8 days. Levels of sulphated glycosaminoglycans were also maximal at 2–4 days (range 0.03–0.126 μg/5 min) and decreased at 6-8 days. Hyaluronan was detected within a similar range of values reaching maximal levels at 4 days and decreasing by 8 days. The results indicate that glycosaminoglycan levels of peri-implant sulcus fluid is an effective means of measuring and maintaining changes in bone metabolism. The absence of proteodermatan sulphate precludes 1 soft tissues being a source of these markers.
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  • 36
    Electronic Resource
    Electronic Resource
    Copenhagen : Munksgaard International Publishers
    ISSN: 1600-0501
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: This case report describes the successful rebuilding of jaw bone for the anchorage of an endosseous implant by applying the principle of “guided tissue regeneration”. The extremely reduced bone volume required reconstructive surgery in 2 stages, the 1st surgical procedure being carried out before the installation of the implant and the 2nd simultaneously with the placement of the implant. The biological prerequisites as well as technical demands for this treatment modality are discussed.
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  • 37
    ISSN: 1600-0501
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The clinical and microbiologic features of 30 hydroxyapatite-coated root-form endosseous dental implants (Tri-Stage) were compared to 10 similar pure titanium implants without hydroxyapatite coatings. In 7 of 9 partially edentulous patients studied, pure titanium fixtures were placed adjacent to hydroxyapatite-coated implants. Implants in the maxilla were submerged beneath mucosal tissues after implant placement for a minimum of 6 months, and in the mandible for at least 4 months. All patients were prescribed short-term beta-lactam antibiotic therapy after fixture placement, and 8 of 9 used chlorhexidine mouthrinses after fixture exposure. Clinical and microbiological examination was carried out 7–10 months after fixed prosthetic loading of the implants. Clinical measurements included the gingival index, plaque index, bleeding on probing and peri-implant probing depths determined with the Florida Probe system. Subgingival microbial samples were collected with paper points and transported in VMGA III. Specimens were examined by direct phase-contrast microscopy and were plated onto nonselective and selective culture media for anaerobic and aerobic incubation. No significant mean clinical or microbiological differences were found between the implant types, although one hydroxyapatite-coated implant exhibited deep probing depths, bleeding on probing and marked radiographic crestal bone loss. Streptococcus sanguis and Streptococcus mitis were the most predominant organisms recovered from clinically stable implants, whereas high proportions of Fusobacterium species and Peptostreptococcus prevotii were isolated from the ailing hydroxyapatite-coated implant. One or more implants in 8 of the study subjects yielded enteric rods, pseudomonads, enterococci or staphylococci. The prognosis of implants with varying early microbiotas needs to be established in longitudinal studies.
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  • 38
    Electronic Resource
    Electronic Resource
    Copenhagen : Munksgaard International Publishers
    ISSN: 1600-0501
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: A Brånemark standard titanium implant and an IMZ plasma flame spray-coated implant were radiographed experimentally under standardized circumstances. Angulations in relation to film plane and central X-ray as well as rotations around the implant's longitudinal axis were varied. The influence of implant architecture on image density and image pattern was analyzed and images of the two types of implants were compared. The Brånemark implant is asymmetric and exhibits only radiographic burnout in its apical area. The 4 vertical apical cuts cause very distracting images and leave the impression that the implant is conical. It is possible to evaluate angulations with great accuracy from the thread profile, but there are limited possibilities for estimation of rotational stages. The ZMZ impfnnt shows symmetric images in any projection. The 4 vertical slits cause a disturbing burnout in the central part of the implant in certain views, and radiographic images are very inconstant. Possibilities of estimating angulation and rotation are varying. Differences in radiographic image characteristics are supposed to influence diagnostic yield as they affect the possibilities of identifying osseointegration radiographically and of controlling image identity in I serial radiography.
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  • 39
    ISSN: 1600-0501
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The aim of this study was to test the effect of chlorhexidine gel application on periodontal health of abutment teeth in patients with overdentures. 19 patients with immediate overdentures were distributed ar random among 2 experimental groups. In these groups, a placebo and chiohexidine gel were daily applied. Patients were recalled at 6-month intervals over a period of 2 years. In both groups, pocket depth, tooth mobility and bleeding index were initially found to decrease after insertion of the overdenture. In the chlorhexidine group. the bleeding index remained very low over the 2-year period. whereas in the placebo group. the bleeding index gradually returned to the baseline values. The pocket depth in the chlorhexidine group remained below the baseline value. in contrast to values in the control group. The width of the attached gingiva decreased in both the groups. but less in the chlorhexidine group.
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  • 40
    ISSN: 1600-0501
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The 15 patients included in this study each had 2-6 permucosal Branemark osseointegrated implants that had functioned successfully for 18 months or more. They were given a full oral examination which included measurements of probing depth and gingival, bleeding and plaque indices around the implants. Marginal bone reduction during the functional life of the implants was estimated from radiographs. At a separate visit, peri-implant sulcus fluid (PISF) was collected on filter paper strips from the deepest probing site of each implant. PISF volumes were measured and the samples eluted into buffer. Protease activities in the eluates were determined by fluorimetric assay with peptidyl derivatives of 7-amino-4-trifluoromethyl coumarin. Enzyme levels followed the order: cathepsin B/L 〉 elastase 〉 dipeptidyl peptidase IV 〉 trypsin-like activity. Total enzyme activities and concentrations both correlated positively with all clinical parameters in linear regression analysis. This was true on both a patient level using mean patient values and a site level using pooled patient data. Nearly all of the site level correlations were statistically significant, though coefficients were generally higher for total enzyme activities than concentrations. Elastase-like activity gave the best overall correlations of the different proteases measured. Amongst the clinical parameters, correlations were generally best with gingival index and bone reduction. Total enzyme activities had good diagnostic specificity and sensitivity as predictors of clinical parameters and the figures were especially high for elastase-like activity as a marker of bone reduction. PISF proteases may thus be of value in monitoring tissue responses to osseointegrated implants.
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  • 41
    ISSN: 1600-0501
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: This paper presents a specific technique for maxillary sinus augmentation and simultaneous placement of implants in partially edentulous patients. In such patients. there is from time to time insufficient interarch distance for any type of onlay grafting. Healthy. non-smoking patients without previous or present sinus pathology. where the radiological and clinicle examination revealed insufficient height and/or width of the remaining alveolar process in the posterior maxillary region, were selected. They were operated on using a mandibular bone graft obtained from the symphyseal region between the mental foramina and placed in the maxillary sinus. The recipient site was prepared by cutting in a rectangular shape the lateral sinus wall into the sinus lining. The bone wall was then separated towards the lateral nasal wall by rotating the inferior portion of the cut sinus wall medially. In the space thus created, the bone graft was placed. Fixtures were installed at the same session. The method described has proved to be uncomplicated to perform under local anesthesia and no major disadvantages for the patient or pre- or postoperative complications have so far been observed.
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  • 42
    Electronic Resource
    Electronic Resource
    Copenhagen : Munksgaard International Publishers
    ISSN: 1600-0501
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: New technology coupled with a better understanding of tissue biology has played a key role in restoring the somewhat tarnished image of implant dentistry. Thanks to carefully conducted longitudinal studies, it has now become clear that the replacement of missing teeth by artificial implants integrated into the living tissues of the jaws is a predictable procedure, as long as certain guidelines are followed in the manufacture of the implant, in its placement, in its eventual functional loading, and in its maintenance (Adell et al. 1981, Aibrektsson 1988, Albrektsson et al. 1988, Babbush et al. 1986, Kirsch & Mentag 1986, Smithloff 1986,Smithloff & Fritz 1987). Yet, functional success for a natural tooth is dependent on a number of anatomic, physiologic, and environmental considerations which differ in some important respects from those that insure the functional success of an implant. In this paper, we review theanatomic features of the natural dentition with emphasis on the periodontal tissues, and contrast these characteristics with those that exist 1 around well-integrated endosseous implants.
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  • 43
    ISSN: 1600-0501
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: A qualitative and quantitative histological study of the initial healing response adjacent to 24 submerged and non-submerged implants placed in the lower jaws of 6 monkeys is presented. The histomorphometric analysis showed no significant differences in mineralized bone-implant contact length between submerged and non-loaded non-submerged titanium implants. The infrabony defects around some of the implants on the radiographs were significantly correlated to the histological measurements. Qualitatively, a greater number of gingival inflammation cells and a longer junctional epithelium were seen adjacent to non-submerged implants without oral hygiene than were seen adjacent to non-submerged implants with oral hygiene in the initial healing period.
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  • 44
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: Portable air pollution samplers were used to measure sulphur dioxide (SO2), nitrogen dioxide (NO2) and respirable suspended particulates (RSP) in a study of a group of nineteen asthmatics during two periods in the winter and summer respectively. One sampler was carried by each subject, one was placed in the home indoors, and one outdoors by the home. In addition, similar pollutants were measured at a central stationary site within a 15 km radius during the same time periods. Samplers were not placed, however, in other indoor spaces where subjects spent part(s) of the day. We used the data from all the sampling sites to develop predictive models for personal exposure. With 330 person-days of exposure data, multiple regression of these “fixed site” measures of pollution against the personal exposure measures revealed a predictive relationship whose power increased proportionally to the time the subjects spent indoors. This relationship was limited, however, since samplers were not placed at other indoor spaces, thus leaving the predictive model incomplete. A pollution index in which these indoor and outdoor pollutant measures were weighted by the time spent at home indoors and outdoors was predictive of personal exposure for NO2 and RSP (R = 0.78,0.44 respectively); the SO2 levels were too low to be used in the comparative analysis (R = 0.19).
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  • 45
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: Concentrations of total volatile organic compounds (TVOC) exceeding 1 mg/m3 have been implicated in the Sick Building Syndrome. Very few measurements of TVOC have been made in homes and buildings in the United States. However, stored gas chromatography-mass spectrometry (GC-MS) data on 12-hour average values of individual VOCs from 750 homes and 10 buildings were available from EPA's Total Exposure Assessment Methodology (TEAM) Studies (1981-88). An initial study to determine the feasibility of obtaining a TVOC value from stored GC/MS data showed that TVOC estimates could be obtained with adequate precision. Therefore TVOC values were calculated for about 2700 personal, indoor, and outdoor air samples collected in the TEAM Studies.More than half of the personal and indoor air samples had TVOC levels exceeding 1 mg/m3, compared to only about 10% of the outdoor air samples. However, these calculated values may not be directly comparable with values determined using different sampling and analytical techniques. Nonetheless, since all samples were collected on Tenax cartridges, which (like all sorbents) adsorb only a portion of the organic chemicals in the air, these values are likely to be underestimates of the total volatile organic loading.
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  • 46
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 1 (1991), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: This paper summarizes the sampling and analysis methods used to collect and quantify polycyclic aromatic hydrocarbons (PAH) and PAH derivatives in indoor and outdoor air at 33 homes heated in two cities, Columbus OH and Azusa CA. Two new samplers were developed far these studies: one with a flow rate of 200 l/min to collect material for bioassay and chemical analysis and a similar one with a flow rate of 20 l/min to collect samples for chemical analysis only. Both samplers simultaneously collect semivolatile organic compounds in the particulate and vapor phases. Both are quiet, transportable, and operate entirely within the sampled environment. The samplers' field performance was evaluated; that of the 20 l/min sampler is discussed in detail. Some typical data and findings from the studies are presented.
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  • 47
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 1 (1991), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: Previous studies to detect fibers emitted by fibrous glass air duct systems have indicated very low concentrations, on the order of 1 × 10−6 to 10 × 10−6 fibers per cubic centimeter. These levels are equivalent to background air. The test protocol and sample evaluation for these studies are expensive and labor-intensive. A new test protocol has been developed that utilizes lower-cost equipment and reduces sample construction and evaluation costs. This new procedure uses multiple tests to increase precision and establish confidence levels for the mean performance of the product. Easily fabricated test sections and statistically sampled collection filters are the primary methods used to reduce costs and shorten total testing time. Results to date agree well with previous studies and demonstrate that fibrous glass duct board does not contribute fibers to the atmosphere. This new protocol is used on a continuing basis to evaluate products and to ensure that there are no changes that affect airstream quality.
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  • 48
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 1 (1991), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: The purpose of this study was to predict how indoor air is perceived when polluted by different materials simultaneously. A panel of five trained judges was exposed to air polluted by each of 11 different single pollution sources. The panel was also exposed to 13 pair combinations of these single pollution sources and to one combination of five sources. The pollution sources comprised typical indoor building materials, materials from ventilation systems and other frequently occurring indoor pollution sources. The results indicate that the total sensory pollution load in a space may, as a first approximation, be predkted by simple addition of the olf values of the single sources.
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  • 49
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: Sampling and analytical methods for gas- and particulate-phase polycylic aromatic hydrocarbons (PAH) in indoor air were evaluated in a controlled field study. Using 12-h, 25-m3 samples, gas-phase PAH were collected on XAD-4 resin and analyzed by GC-MS, and particulate-phase PAH were collected in filters and analyzed for by HPLC with fluorescence detection. Tests were conducted in homes and office buildings without active combustion sources and with gas stoves, wood stoves and cigarette smoking as controlled sources. Indoor concentrations, outdoor concentrations and air-exchange rates were simultaneously measured. The precisions of the concentrations were evaluated using collocated sample pairs collected indoors and outdoors. Net emission rates were calculated for the gas-phase PAH. Net emissions of these compounds were measured in buildings without active combustion sources. Environmental tobacco smoke was identified as a significant source of both gas- and particulate-phase PAH.
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  • 50
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 1 (1991), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: This is a case study of the radon diagnostics and mitigation performed by the U.S. Environmental Protection Agency's (EPA's) Office of Research and Development in a New York State school building. Research focused on active subslab depressurization (ASD) in the basement and, to a lesser degree, the potential for radon reduction in the basement and slab-on-grade sections using the heating, ventilating, and air-conditioning (HVAC) system.Based on radon diagnostic measurements in the basement, a five-point ASD system was installed, and recommendations were made to increase the outdoor air supply through the basement unit ventilator. Because of the high radon levels in the basement (1720 bequerels per cubic meter, Bq m−3) and limited subslab pressure field extension, both mitigation approaches were needed to reduce radon to below the current EPA guideline of 148 Bq m−3. The effects of excavating a suction pit under each of the five suction points were also investigated. Pit excavation, together with adjustment of the airflows at the suction points, decreased average radon levels in the basement by an additional 40 percent.In the slab-on-grade section, it was recommended that the school hire a HVAC contractor to evaluate the unit ventilators for increased outdoor air supply. This was recommended both to improve indoor air quality and because diagnostic measurements indicated that an ASD system would require an excessive number of suction points in the slab-on-grade classroom.
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  • 51
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 1 (1991), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: The Multichamber Consumer Exposure Model (MCCEM) is a user-friendly computer program that can be used to estimate indoor air concentrations and occupant inhalation exposures for chemicals released from products, materials, furnishings or appliances in structures such as residences. Among the major features of MCCEM are flexibility in running the model for durations from one hour to one year, a library of infiltration and interzonal airflow measurements for several hundred U.S. residences, a spreadsheet for input of time-varying emission rates, the ability to estimate inhalation exposure, and options for Monte Carlo simulation and sensitivity analysis. An illustrative application is given whereby assumptions concerning the emission profile and the number of chambers to be modeled are examined for impact on exposure estimates. Discussion is provided on the importance of model validation and an approach to validation is given for the illustrative application.
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  • 52
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 1 (1991), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: Field measurements of the concentration and activity size distribution of radon decay products were conducted in a one-story house located in the Princeton, NJ area. Radon concentration and particle number concentration were also measured. The concentration and activity-weighted size distribution of radon decay products were determined using a microcomputer-controlled, semi-continuous screen diffusion battery system with 6 parallel sampler/detector units. A condensation nuclei counter was used for the measurements of indoor panicle number concentration. Several measurements were made in the living room as well as more than one hundred measurements in the master bedroom of the Princeton house. Aerosols were generated from taking a shower, burning a candle, smoldering a cigarette, vacuuming, and cooking. Therefore, the influence of various indoor panicle sources on the behavior of radon decay products was investigated. With panicles generated from typical household activities, Potential Alpha Energy Concentration (PAEC) increases and the unattached fraction decreases. Larger panicles generated from cigarette smoke and cooking dramatically shifted most of the radon decay products into the attached mode (15-500 nm). With regard to the higher attachment rate, the size distributions of radon decay products remained stable for long periods of time after particle generation. On the other hand, aerosols produced from candle burning and vacuuming were much smaller, with an average attachment diameter of 15 nm. These panicles did decrease the unattached fraction, especially during the aerosol generation period. However, the size distributions of radon decay products returned to the background condition within ISO minutes after the end of particle generation. In these cases, the panicles had a higher deposition rate and a lower attachment rate. The dose of alpha radiation per unit radon concentration resulting from each of these aerosol conditions was calculated using the measured activity size distributions and the most recent James dosimetric model. These doses to basal cells at a breathing rate of 0.45 m3 hr1 ranged from 3 to 14 μGy Bq−1 hr while the dose to secretory cells at a breathing rate of 1.5 m3 hr1 ranged from 13 to 77 μGy Bq−1 hr for the various aerosol conditions.
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  • 53
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 1 (1991), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: This paper discusses three methods for measuring inter-zonal air movements in two-zone buildings: initial injection of one tracer into a single room, repeated injection of one tracer into two rooms, and initial injection of two tracers into two rooms. The description of these methods includes an outline of the theoretical background, the presentation of suitable injection strategies and algorithms for the evaluation of the concentration profiles. A detailed error analysis using Monte-Carlo-simulation shows the precision of these methods for a variety of cases, such as different magnitudes of the inter-zonal airflows and various measurement durations.
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  • 54
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 1 (1991), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: A parametric cost analysis was conducted to determine the importance of various system design and operating variables on t h installation and operating costs of active soil depressurization (ASD) systems for indoor radon reduction in houses. The objective was to help guide the research and development (R&D) efforts of the US. Environmental Protection Agency (EPA) to reduce ASD costs. Annual lung canter deaths due to radon cannot be reduced by more than about 14% to 22% unless houses having pre-mitigation levels of 148 Bqlm3 and less receive radon reduction systems. Reductions in ASD costs might increase voluntary use of this technology by homeowners at those levels. The analysis showed that various modifications to ASD system designs offer potential for reducing installation costs by up to several hundred dollars/〉, but would not reduce total installed costs much below $800–$1000. Reductions of this magnitude would probably not be sufficient to dramatically increase voluntary use of ASD technology. Thus, some innovative, inexpensive mitigation approach other than ASD would appear to be necessary. Decreased ASD fan capacity and increased sealing might reduce ASD operation costs (for fan electricity and house heating/cooling) by roughly $7.50 per month. It is unlikely that this amount would be a deciding factor for most homeowners.
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  • 55
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: A chamber method for the characterization of the complex composition and time dependence of volatile organic compound (VOC) emissions from household products is described and the results obtained for five household products (two liquid floor detergents, one wax, a spray detergent for carpets, and a spray polish for furniture) are reported and compared to headspace measurements.An empirical mathematical model has been used to describe the time dependence of VOC concentrations in the chamber. The model allows characterization of complex emissions and their time dependence with relatively few parameters.Significant differences in the composition of emissions determined in the chamber and in headspace air have been observed and are discussed in terms of polarity and water solubility of the emitted compounds.
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  • 56
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 1 (1991), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: A new turbinemeter has been developed to be used as a ventilation rate sensor in livestock buildings. On the basis of a previous sensor introduced in 1983, several improvements have been made to develop a low-cost airflow rate sensor with an acceptable accuracy of 60 m3/h in a range from 200 to 5000 m3/h for pressure differences from 0 to 120 Pa. This sensor can be integrated in the climate control equipment of livestock buildings to improve process control.
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  • 57
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: Initation of the eyes and the upper respiratory tract (sensory irritation) in man due to the emission of vapours and gases from water-based indoor paints has been estimated from their ability to decrease the respiratory rate in mice (ASTM: E981-84, slightly modified). An acid-curing lacquer, known to give rise to sensory irritation during occupational exposure, was used as the positive control. In the bioassay the and-curing lacquer also gave rise to a pronounced sensory irritation, confirming that the ASTM method was applicable. Furthermore, the emission of formaldehyde, bases and acids was determined. The irritation within the first week was mainly due to the emission of organic solvents, but formaldehyde also played a role. Later the sensory irritation effect was caused mainly by the emission of formaldehyde. This indicates that the method revealed the different emission phases. None of the water-based paints (3 latex wall paints, 1 silicate paint and 1 distemper) gave rise to a biologically significant irritation effect. Nor did the water-based products emit formaldehyde or acids. However, varying degrees of emission of ammonia were observed. Taking into account the biological detection limits, no significant degree of sensory irritation can be expected in man 1-2 weeks after indoor painting with the tested water-based products.
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  • 58
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: The effects of mechanical ventilation on the sick building syndrome (SBS) were studied in an office building with 2150 employees, where the mechanical ventilation and indoor air quality were commonly blamed for causing symptoms typical of the SBS (nasal, eye, and mucous membrane symptoms, lethargy, skin symptoms and headache). The mechanical ventilation rates in the building were high (mean 26 l/s/person). To test the hypothesis that mechanical ventilation causes the SBS, a controlled experimental study was carried out by shutting off the ventilation in one part of the building and reducing the ventilation rate by 75% and 60% in two areas while leaving one part unaltered as a control. The experimental reduction of the ventilation rate did not alleviate the symptoms. On the contrary, the reduction of the ventilation rate caused a slight but statistically significant relative increase in symptoms (p 〈 0.05). In the cross-sectional analysis of the baseline data the SBS symptoms did not associate significantly with the ventilation rate (range 7–70 l/s/person). In the linear regression model, a positive correlation was found between temperatures above 22°C and the occurrence of symptoms (p 〈 0.05). Subjects exposed to environmental tobacco smoke had more symptoms than those not exposed (p 〈 0.01). Women reported more symptoms than men (p 〈 0.001). In addition, any prior history of allergic diseases (p 〈 0.001) and a negative attitude towards the social atmosphere at work (p 〈 0.001) were significant determinants of the SBS.
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  • 59
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 1 (1991), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: Displacement ventilation is acknowledged to be an efficient system for the removal of contaminants and excess heat from occupied zones of rooms. However, airflow rates, temperature and the design of the air supply device strongly influence the parameters which determine thermal comfort. This paper reviews experiments and theoretical models which show the connection between these parameters. The width and shape of the air supply device have been varied, and a porous media has been used on the inlet area of the air supply device. The velocity and temperature profiles have been measured. The results presented show also that the flow can be described with respect to width and form of the profiles for temperature and velocity. The flow does not operate like a turbulent jet due to thermal stratification. It is shown that the Archimedes number of the supply air is the parameter which determines the air velocity in the area close to the floor. (The Archimedes number is here defined as the ratio between buoyancy and inertia forces.) The results show that it is possible to remove considerable amounts of excess heat from a room, typically 40-50 W/m2, without exceeding the limits for thermal comfort. However, this requires relatively high airflow rates and supply air terminal units at least along one of the walls.
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  • 60
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 1 (1991), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: In recent yean, some building design professionals have become more aware of the indoor air quality concerns of owners and occupants and as a result, they have made some important changes to improve indoor air quality and climate. These changes include improvements in site planning and design; overall building design; ventilation and climate control systems; and materials selection and specifications. In addition, changes that limit the chemical contamination of building air during the construction process and during occupancy of buildings are also occurring; some of these changes are specified or controlled by design professionals. However, the majority of design professionals have little or no awareness of indoor air quality considerations. There is inadequate dissemination of building science research results to design professionals. There is a need for a useful general body of knowledge, theory, and practice regarding building-environment-occupant interactions. The lack of such knowledge, theory, and practice is an impediment to developing the necessary professional design tools and practices to address effectively indoor environmental quality and energy conservation issues.
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  • 61
    ISSN: 1600-0501
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Lack of bone in localized areas of the jaws frequently poses a problem when placing oral implants. In this clinical study, we have tested an osteopromotive membrane technique for its ability to create bone over buccal fenestrations after fixture installation in the maxilla. 7 patients were selected by the use of CT-scan. Criteria for patient selection were that the alveolar crest should have a vertical height 〉I3 mm and a facial-palatal concavity, where exposure at the central portion of the fixture could be anticipated. One fenestration, randomly chosen, in each patient was covered with an e-PTFE (expanded polytetrafluoroethylene)(Gore-Tex GTAM™) membrane. Contralateral fenestrations served as controls (without the placement of a membrane). The amount of newly formed bone was calculated by photometric assessments. The results showed that the fixture fenestrations, treated with the membrane technique, demonstrated a significantly (p 〈0.005) higher amount of new bone formation compared to the controls, where little or no improvement had taken place at the fenestrations. The study conclusively shows that the membrane technique is a reconstructive technique, able to create new bone at localized bone fenestrations at titanium fixtures. Additionally. the study also demonstrates that the periosteum alone, in adult humans. is not capable of generating new bone at exposed titanium implants.
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  • 62
    ISSN: 1600-0501
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The aim of the present study was to explore the possibility of achieving osseointegration of dental titanium implants, inserted into alveoli immediately after tooth extraction, by covering the recipient site with a teflon membrane. In each of 7 monkeys, mucoperiosteal flaps were raised on the buccal and palatal aspects of the maxillary molars in both sides of the jaw. The second molars were then extracted and self tapping titanium implants of the screw type (Astra® Dental Implants) were inserted into the sockets of the largest roots. In the coronal portion of the sockets, a void was always present between the implant and the socket walls. In one side of the jaw, a membrane (Gore-;Tex Aug-mentation Material@) was adjusted to cover the implant. The implant in the other side of the jaw served as control and was only covered by the tissue flaps. Microscopic analysis after 3 months of healing revealed that soft tissue was facing the coronal portion of the implants to a varying degree in the control side, while osseointegration was consistently observed to the top of the membrane-covered implants which remained submerged throughout the experimental period. The results suggest that the membrane techniaue can secure complete osseointegration of implants inserted immediately into extraction sockets.
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  • 63
    ISSN: 1600-0501
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: 7 clinically stable, “osseointegrated”, titanium implants, inserted in human jaws for l–16 years, were retrieved for morphological analysis of the bone-titanium interface, using 3 different preparation techniques. The bone-titanium interface varied as judged from light microscopy of ground sections. The threads of the implants were well filled 79–95% with dense lamellar bone as quantified with morphometry. A large fraction of the implant surface (56–85%) appeared to be in direct contact with the mineralized bone. In general, the non-boric areas consisted of pockets with osteocytes, bone marrow tissue and/or vessels. Sections were prepared for light microscopy and transmission electron microscopy using a fracture technique. where the implant was separated from the embedded tissue before sectioning, and an electropolishing technique, where the bulk part of the implant was electrochemically removed. In areas judged as direct mineralized bone-titanium contact in the light microscope. the interfacial structure varied at the ultrastructural level. In areas along the interface, unmineralized tissue was present either as a narrow 0.5–l μm wide zone containing collagen fibril or as deeper pockets containing osteocytes or vessels. In areas with mineralized bone contact. an amorphous granular layer (100–400 nm wide) with no mineral was observed in the innermost interface bordering the mineralized bone, with an electron-dense lamina limitans-like line (approximately 50 nm thick). It is concluded that the bone-titanium interface of the 7 clinically retrieved titanium oral implants examined in the present study bone was heterogenous. In areas of a direct mineralized bone-titanium contact at the ultrastructural level. mineralized bone reached close to the implant surface, but was separated by an amorphous layer. 1 being 100–400 nm thick.
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  • 64
    Electronic Resource
    Electronic Resource
    Copenhagen : Munksgaard International Publishers
    ISSN: 1600-0501
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The microflora associated with osseointegrated implants suspected of failing from infection or trauma were evaluated. Of 75 patients examined, 11 demonstrated failing fixtures. 22 of 48 fixtures failed in 6 fully edentulous patients and 10 of 34 failed in 5 partially edentulous patients. The etiology of failure was attributed to infection if there was bleeding, suppuration, pain, high plaque and gingival indices and granulomatous tissue upon surgical removal. Traumatic etiology was suspected in the absence of these signs. Direct phase-contrast microscopy and culture analysis were performed on samples from the implant sulcus, the implant itself and the extraction socket. The 2 failure types exhibited distinct bacteriologic profiles. For implants failing with infection, spirochetes and motile rods averaged 42% of total morphotypes. Many suspected periodontopathic organisms including Peptostreptococcus micros, Fusobacterium species, enteric gram-negative rods and yeasts, constituted high proportions of the cultivable microflora. In contrast, implants failing from suspected traumatic etiology demonstrated a morphotype profile consistent with periodontal health and cultivable microflora predominated by streptococci. When evaluating the time of failure after initial insertion, it was found that fixture loss resulting from infection occurred most often between initial placement and second-stage surgery, whereas failure in the absence of infection occurred primarily after insertion of the final prosthesis. The terms infectious and traumatic failure have been introduced to describe these 2 clinically and microbiologically distinct phenomena.
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  • 65
    ISSN: 1600-0501
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Successful attachment of the oral tissues to an endosseous dental implant relies in part on its chemical stability, nontoxic properties and maintenance of normal cell functions in the surrounding tissues. The aim of this study was therefore to investigate these 3 factors experimentally. The corrosion resistance of single crystal sapphire (a -αl,O,) implants was analysed with respect to the release of aluminium ions; no ions could be detected in the test solutions. The influence of single crystal sapphire on the behaviour of human epithelial cells and fibroblasts derived from biopsies of the oral mucosa, was studied. The cells were cultured in chemically defined or in low serum-containing media. Compared to the corresponding control cultures, no effects on cell morphology and growth characteristics were observed. Sapphire rods were in-serted subcutaneously into rats and tissue responses were examined after 4, 8 and 12 weeks post-implantation. None or slight reactions were found in the tissues. The combined evaluation of these experimental approaches indicates that single crystal sapphire is a material well suited for biological implantation.
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  • 66
    Electronic Resource
    Electronic Resource
    Copenhagen : Munksgaard International Publishers
    ISSN: 1600-0501
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: To clarifv more of the tactile function of oral implants, both an interocclusal thickness detection and discrimination task were carried out in 4 different test conditions on 37 patients: t (tooth)/t, i (implant)/t. i/i and d (denture)/0 (overdenture supported by implants). For the interocclusal detection of steel foils. the 50percnt; detection threshold level (RL) in the 4 conditions was 20, 48, 64 and 108 pm, respectively. which indicates significant differences. The ability to discriminate interdental thickness differences was tested with a 0.2 and 1.0 mm standard. It was evaluated as the 75% discrimination level (DL). In the 0.2 mm discrimination task, corresponding DL-values for the t/t, i/t, i/i and d/o condition were 25, 55, 66 and 134 μm, whereas the 1.0 mm standard gave values of 193. 293, 336 and 348 μm. respectively. All results differed significantly from each other (p〈0.05) except for the i/i-d/o comparison of the 1.0 mm discrimination task where the difference was negligible. The present findings indicate that the tactile sensibility of implants is reduced with regard to natural teeth. Remaining receptors of the peri-implant tissues might play a compensatory role in the decreased exteroceptive I function.
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  • 67
    Electronic Resource
    Electronic Resource
    Copenhagen : Munksgaard International Publishers
    ISSN: 1600-0501
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Identity of film positioning and of X-ray beam angulation is essential for valid comparisons of marginal bone height around osseointegrated implants. The purpose of the present study was to analyze the possibilities of estimating fixture angulation in relation to film plane from the threads of Brånemark fixtures. 10 observers compared 62 images of fixtures with angulations ranging from 0" to ± 15" with a set of reference radiographs. Out of 620 recordings, 29% were right, and 71% differed by ≥ 1". The observers distinguished with great accuracy between negative and positive angulations. 81% of the recordings differed by 2" or less. It is concluded that the threads of Brånemark fixtures are helpful in controlling the identity of serial radiographs of implants. The test circumstances were ideal compared to clinical cases, and it is possible that accuracy will be less in patient cases.
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  • 68
    ISSN: 1600-0501
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Different studies have shown that various substances may have an influence on early human dental plaque formation. The purpose of the present study was to compare on tooth substances and supporting prosthetic materials the amount of plaque deposition by SEM and the quantity of selected bacteria using anaerobic culturing techniques. 5 bridges, replacing a missing molar or premolar, were incorporated in 3 patients. In the midbuccal area of each pontic, a semi-precision attachment was placed allowing the insertion of the following test facings: enamel, dentine, non γ2-amalgam, alloys of 85% and 55% gold, silver-palladium, chrome-cobalt, chrome-cobalttitanium, and ceramic. For each material, 2 facings were fabricated. After 4 and 24 hours in situ, bacteriological samples were taken and processed for further identification. After a 2nd period of 4 and 24 hours in situ, the same facings were carefully removed and prepared for SEM-examination. All 4-hour specimens exhibited various areas covered by plaque, the amount of which varied with the different supporting substances. The very smooth surfaces (e.g., gold) harbored sparse deposits, while the rougher (e.g., amalgam) were covered by more plaque. After 24 hours of plaque development, an increase in the number of micro-organisms was noted for all the specimens. After 4 and 24 hours of plaque accumulation, no specific trends suggesting a preferential colonization on the different substances were observed. This study has shown that the amount of early deposits on different substances seems to be related to the degree of their surface roughness, while plaque formation was qualitatively similar.
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  • 69
    ISSN: 1600-0501
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The purpose of the present study was to examine the effect of treating bony craters around titanium dental implants with polytetrafluoroethylene membranes PTFE, with and without grafting of hydroxyapatite (HA), and with HA alone. 4 standardized bone defects were prepared in the alveolar ridge of edentulous areas in each of 7 monkeys. A titanium implant was then placed centrally in each defect, and in each monkey, the defects were treated with 1 of the following 4 treament modalities: 1 coverage with PTFE membrane;(2) grafting of HA and covering with a PTFE membrane;(3) HA grafting;(4) no treatment. Following a healing period of 12 weeks, all animals were sacrificed and mesiodistal ground sections of the treated areas were prepared. The histological analysis showed that all bone defects around the implants treated with PTFE membranes and 5 of the defects treated with HA and PTFE membranes were completely filled with new bone. The defects treated with HA alone and the control defects with no treatment only demonstrated new bone formation in the bottom of the defects. The results suggest that bone defects around titanium implants can be 1 treated successfully with PTFE membranes.
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  • 70