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  • 1
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    Wellesley, MA : Wellesley-Cambridge Press
    Call number: TK7870:2
    Keywords: Electric filters / Mathematics ; Signal processing / Mathematics ; Wavelets (Mathematics) ; Image Processing, Computer-Assisted ; Mathematical Computing ; Signal Processing, Computer-Assisted
    Pages: xxi, 520 p.
    ISBN: 0961408871
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  • 2
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The analysis of total Hg in various environmental matrices was investigated using energy dispersive X-ray fluorescence (EDXRF) for both powdered and digested samples and cold vapor atomic absorption (CV-AAS) for digested samples. Several microwave decomposition procedures were evaluated with respect to the determination of Hg by CV-AAS and EDXRF. The use of different acid mixtures, microwave power settings and decomposition times were compared as well as the analysis on wet and freeze-dried samples. A set of standard reference samples were used to evaluate the procedures: NBS Citrus leaves (1572), NRC Pine needles (1575), NRC Dogfish muscle tissue (DORM-2), NRC Dogfish liver tissue (DOLM-2), BCR Human hair (397), BCR Coking coal (181) and NRC Marine sediment (PACS-1). An H2SO4/HNO3/H2O2 acid mixture was found to be optimal for the complete mineralization and digestion of biological samples for Hg by CV-AAS whereas for EDXRF both the HNO3/H2O2 and H2SO4/HNO3/H2O2 acid mixture gave good results. The detection limit of EDXRF could significantly be decreased (from 0.2 μg/g to 0.058 μg/g) by performing the analysis with digested samples. A good agreement was obtained between CV-AAS and EDXRF analysis. The obtained results were also in good agreement with certified values. The methods were applied to environmental samples (coal, trees, leaves, spinach, fish, sediments) and human hair in a coal mining area and in places where they use coal for cooking in Vietnam.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1181
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Description / Table of Contents: Zusammenfassung  In der Arbeit wird über die Ergebnisse einer numerischen Studie, betreffend die stationäre Konvektionsströmung und den stationären Wärmeübergang in einer rechteckigen, mit einem porösen, phasenveränderlichen Medium (PCM) verfüllten Kavität, berichtet. Den zwei vertikalen Berandungen der Kavität sind zwei, den Schmelzpunkt des PCM einschließende Temperaturen aufgeprägt, während die beiden horizontalen Berandungen adiabat gehalten werden. Das poröse Medium ist durch einen anisotropen Permeabilitätstensor charakterisiert, dessen Hauptachsen bezüglich des Gravitationsvektors beliebig orientiert sein können. Das Problem ist durch das Seitenverhältnis A, die Rayleigh–Zahl Ra, das Anisotropienverhältnis R und den Orientierungswinkel Θ des Permeabilitätstensor bestimmt. Hauptaugenmerk gilt dem Einfluß der anisotropen Permeabilität auf das Strömungsverhalten und den Wärme-übergang beim Phasenwechselprozeß flüssig/fest. Die Lösungsmethode basiert auf dem Kontrollvolumenprinzip in Verbindung mit der Landau-Transformation über welche das irreguläre Strömungsgebiet in ein rechteckiges abgebildet wird. Ergebnisse bezüglich Strömungsfeld, Temperaturverteilung, Phasengrenzenort und Wärmeübergang werden fürA=2, 5;Ra=40; 0≤Θ≤π; 0, 25≤R≤4 mitgeteilt. Es zeigte sich, daß der Gleichgewichtszustand des Phasenwechselsprozesses fest/flüssig sowohl durch das Anisotropieverhältnis R als auch durch den Orientierungswinkel Θ des Permeabilitätstensors wesentlich beeinflußt werden kann. Zum einen existiert bei festgehaltenen ParameternA, Ra undR eine optimale Orientierung Θmax, bei der die Stromstärke, das Flüssigkeitsvolumen und der Wärmestrom Maximalwerte erreichen, während für Θmin=Θmax+π/2 Minimalwerte resultieren. Ist das anisotrope Medium entlang der Optimalrichtung Θmax orientiert, so ergibt sich zum anderen, daß eine Vergrößerung der in diese Richtung fallenden Permeabilitätskomponente die Stromstärke und den Wärmestrom in gleichem Maße erhöht, während eine Vergrößerung der anderen Permeabilitätskomponente nur vernachlässigbaren Einfluß hat. In den untersuchten Parameterbereichen lag die Optimalrichtung zwischen dem Gravitationsvektor und der Hauptstromrichtung.
    Notes: Abstract  This paper reports on the results of a numerical study of convection flow and heat transfer in a rectangular porous cavity filled with a phase change material under steady state conditions. The two vertical walls of the cavity are subject respectively to temperatures below and above the melting point of the PCM while adiabatic conditions are imposed on the horizontal walls. The porous medium is characterized by an anisotropic permeability tensor with the principal axes arbitrarily oriented with respect to the gravity vector. The problem is governed by the aspect ratioA, the Rayleigh numberRa, the anisotropy ratioR and the orientation angle θ of the permeability tensor. Attention is focused on these two latter parameters in order to investigate the effects of the anisotropic permeability on the fluid flow and heat transfer of the liquid/solid phase change process. The method of solution is based on the control volume approach in conjunction with the Landau-transformation to map the irregular flow domain into a rectangular one. The results are obtained for the flow field, temperature distribution, interface position and heat transfer rate forA=2.5,Ra=40, 0≤θ≤π, 0.25≤R≤4. It was found that the equilibrium state of the solid/liquid phase change process may be strongly influenced by the anisotropy ratioR as well as by the orientation angle θ of the permeability tensor. First, for a given set of parametersA,Ra andR, there exists an optimum orientation θmax for which the flow strength, the liquid volume and the heat transfer rate are maximum. There also exists an orientation θmin=θmax+π/2 for which these quantities are minimum. Second, when an anisotropic medium is oriented along the optimum direction θmax, an increase of the permeability component along that direction will increase the flow and heat transfer rate in a same order while an increase of the other permeability component only has a negligible effect. For the parameter ranges considered in the present study, it was found that the optimum direction is lying between the gravity vector and the dominant flow direction.
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  • 4
    ISSN: 1433-2965
    Keywords: Direct costs ; Epidemiology ; Fractures ; Health economics ; Osteoporosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Osteoporosis is an increasing health care problem in all aging populations, but overall direct costs associated with the total fracture burden of osteoporosis remain uncertain. We have examined direct costs associated with 151 osteoporotic fractures occurring between 1989 and 1992 in a large cohort of elderly men and women followed prospectively as part of the Dubbo Osteoporosis Epidemiology Study. The median cost of hospital treated fractures was $A10 511 per fracture and for fractures treated on an outpatient basis $A455 in 1992 Australian dollars. Femoral neck fractures were the most expensive fractures ($15984 median cost). There was no significant difference in costs between men and women for either hospital- or outpatient-treated fractures. Rehabilitation hospital costs comprised the largest proportion of costs (49%) for hospital-treated fractures. Community services comprised the major cost (40%) of outpatient-treated fractures. Univariate predictors of costs were quadriceps strength and bone density, although multivariate analysis showed quadriceps strength to be the best overall predictor of costs. The predicted annual treatment costs in Australia for atraumatic fractures occurring in subjects ⩾60 years was $A779 million or approximately $A44 million per million of population per annum. Estimated total osteoporotic fracture-related costs for the Australian population were much higher than previously reported. The majority of direct costs (95%) were incurred by hospitalized patients and related to hospital and rehabilitation costs. Extrapolation of these data suggests that the direct costs for hip fracture alone will increase approximately twofold in most Western countries by 2025. Improving the cost-effectiveness of treating osteoporotic fractures should involve reduced hospitalization and/or greater efficiency in community rehabilitation services. The costs of various approaches to osteoporosis prevention must be placed into the context of these direct costs and prevention should target men as well as women.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1433-2965
    Keywords: Biochemical assay ; Bone densitometry ; Bone turnover ; Menopause ; Osteoporosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A number of recent studies have suggested that non-invasive measures of bone turnover are associated with bone loss at the forearm in postmenopausal women. Whether bone turnover markers are predictive of bone loss from the clinically important sites of lumbar spine and femoral neck remain unclear, and was the aim of this 4-year prospective study. One hundred and forty-one normal, postmenopausal women (mean age 52.0±3.3 years, mean menopause duration 20.4±5.7 months) were recruited for the study in 1988. Fasting early morning samples of blood and urine were collected at the baseline visit and stored at −20 °C prior to analysis. Serum was assayed for osteocalcin, oestradiol, oestrone, oestrone sulphate, testosterone, sex hormone binding globulin, dehydroepiandrosterone sulphate and total alkaline phosphatase. Urine was assayed for calcium, hydroxyproline, oestrone glucuronide and the collagen cross-links pyridinoline and deoxypyridinoline using high-performance liquid chromatography. Bone density was measured at the lumbar spine and femoral neck using dual photon absorptiometry at time 0, 12, 24 and 48 months. The mean annual percentage change in bone density (SE) was −1.41% (0.18) at the lumbar spine and −0.86% (0.22) at the femoral neck. There was no evidence of bimodality or a fast loser subgroup as the rates of change were normally distributed. Both simple and multiple stepwise regression analyses revealed no significant correlation between the rates of change in bone density with any biochemical marker, either individually or in combination, despite the study having sufficient power (80%) to detect a correlation of 0.5 between any biochemical marker levels and bone loss. We conclude that single measurements of these markers of bone turnover and endogenous sex hormones appear unlikely to be clinically useful in predicting early postmenopausal bone loss from either the spine or the hip.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1433-7339
    Keywords: Key words Low-energy laser ; Mucositis ; Radiotherapy ; Head and neck cancer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Use of the low-energy helium-neon laser (LEL) appears to be a simple atraumatic technique for the prevention and treatment of mucositis of various origins. Preliminary findings, and significant results obtained for chemotherapy-induced mucositis in a previous phase III study, prompted a randomized multicenter double-blind trial to evaluate LEL in the prevention of acute radiation-induced stomatitis. Irradiation by LEL corresponds to local application of a high-photon-density monochromatic light source. Activation of epithelial healing for LEL-treated surfaces, the most commonly recognized effect, has been confirmed by numerous in vitro studies. The mechanism of action at a molecular and enzymatic level is presently being studied. From September 1994 to March 1998, 30 patients were randomized. Technical specification: 60 mW (25 mW at Reims, 1 patient), He-Ne, wavelength 632.8 nm. The trial was open to patients with carcinoma of the oropharynx, hypopharynx and oral cavity, treated by radiotherapy alone (65 Gy at a rate of 2 Gy/fraction, 5 fractions per week) without prior surgery or concomitant chemotherapy. The malignant tumor had to be located outside the tested laser application areas (9 points): posterior third of the internal surfaces of the cheeks, soft palate and anterior tonsillar pillars. Patients were randomized to LEL or placebo light treatment, starting on the first day of radiotherapy and before each session. The treatment time (t) for each application point was given by the equation : t (s)=energy (J/cm2)×surface (cm2)/Power (W). Objective assessment of the degree of mucositis was recorded weekly by a physician blinded to the type of treatment, using the WHO scale for grading of mucositis and a segmented visual analogue scale for pain evaluation. Protocol feasibility and compliance were excellent. Grade 3 mucositis occured with a frequency of 35.2% without LEL and of 7.6% with LEL (P〈0.01). The frequency of "severe pain" (grade 3) was 23.8% without LEL, falling to 1.9% with LEL (P〈0.05). Pain relief was significantly reduced throughout the treatment period (weeks 2–7). LEL therapy is capable of reducing the severity and duration of oral mucositis associated with radiation therapy. In addition, there is a tremendous potential for using LEL in combined treatment protocols utilizing concomitant chemotherapy and radiotherapy.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1433-2965
    Keywords: Osteoporosis ; Vertebral ; Fractures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The aims of this study were to ascertain vertebral deformity prevalence in elderly men and women and to describe the association between bone mineral density (BMD) at the lumbar spine and femoral neck, severity of spinal degenerative disease and vertebral deformity prevalence. We performed standardized spinal radiographs in a random sample of 300 elderly men and women participating in the Dubbo Osteoporosis Epidemiology Study, a population-based study of fracture risk factors. Radiographs were read independently by masked observers for the prevalence of vertebral deformity and severity of osteophytosis. BMD was measured by dual-energy X-ray absorptiometry. The prevalence of vertebral deformities was critically dependent on the criterion used. The less strict criteria seemed to overestimate deformities at either end of the spine region analysed. However, irrespective of the criterion used, prevalence of deformity was higher in men than in women (25% vs 20% for the 3 SD criterion, 17% vs 12% for the 4 SD criterion and 27% vs 25% for the 25% criterion). Femoral neck BMD was more strongly associated with vertebral deformities than spinal BMD for the 25% criterion (OR/SD change in BMD 1.39 (p=0.02) vs 1.20 (p=0.19)), 3 SD criterion (OR/SD change in BMD 1.45 (p=0.01) vs 1.10 (p=0.34)) and 4 SD criterion (OR/SD change in BMD 1.98 (p=0.0002) vs 1.68 (p=0.008)). BMD was also more strongly associated with biconcave deformities than either wedge or crush deformities and more so in men than in women. Severity of spinal osteophytosis was not associated with vertebral deformity. In conclusion, femoral neck BMD is at least equivalent to the lumbar spine BMD in strength of association with prevalent vertebral fractures. Spinal osteophytosis falsely elevates BMD without a concomitant decrease in fracture risk, indicating that any interpretation of spinal BMD needs to be adjusted for osteophytosis. These findings support the use of femoral neck bone densitometry in older men and women. Moreover, these data indicate that current criteria for radiological assessment of vertebral deformity are sufficiently loose to include a substantial proportion of non-fractures in the elderly, with important implications for the design of clinical trials. However, irrespective of the criterion used, vertebral deformities in men are at least as common, if not more so, than in women, suggesting that vertebral osteoporotic fractures are overlooked in men.
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  • 8
    ISSN: 1433-2965
    Keywords: Handedness ; Osteoporosis ; Physical activity ; Study design ; Ultrasound
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Calcaneal ultrasound has been increasingly studied for its potential in the assessment of osteoporotic fracture risk. The accuracy of such an assessment is, in part, dependent on the reproducibility of the measurement. This study examines the impact of handedness on ultrasound measurements [broadband ultrasound attenuation (BUA) and velocity of sound (VOS)] in the calcaneus. Two hundred and sixty-four subjects (57 men and 297 women) aged 51.1+13.6 years (mean ± SD) were studied. For each subject, calcaneal ultrasound measurements were performed on both heels with a McCue CUBA ultrasound densitometer. Right-handed dominance (94.7%) was determined by structured interview. In men, BUA measurements were significantly higher on the dominant side: mean difference 4.1±1.5 dB/MHz (mean ± SD;p=0.009), equivalent to 4.2+1.5% and more than 4 times the average rate of annual change in BUA. The difference between sides was greater in young (〈50 years) than old men (〉50 years). Among the women, the difference was not statistically significant (0.7±0.9 dB/MHz;p=0.4); however, it was significant in younger women (20–30 years) (99±4 vs 90±4 dB/MHz,p=0.01). By contrast VOS did not differ between sides in either men or women irrespective of age. Within-subject standard deviation of BUA was 9.8 dB/MHz for men and 8.6 dB/ MHz for women and the component due to right and left difference was 8.4 dB/MHz for men and 6.9 dB/MHz for women. This variability of BUA between right and left heels could increase the false-positive rate by up to 28% for a cut-off of 2 SD below the mean. These data indicate that variation between left and right heel measurements of BUA is higher than that of random error measurements, particularly in men and younger, presumably more physically active subjects. Although VOS measurements were not side dependent, in the smaller number of studies examining VOS and fracture risk, VOS appears to have a weaker predictive power than BUA. Clinical and epidemiological studies involving calcaneal BUA measurements should standardize the side measured to either the dominant or non-dominant heel, to reduce within-subject variation and increase their power.
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  • 9
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Cell walls, representing 26%–32% of the cell dry weight, were prepared from several strains of the yeasts Kloeckera apiculata, Debaryomyces hansenii, Zygosaccharomyces bailii,Kluyveromyces marxianus and Saccharomyces cerevisiae. Extraction of the walls with potassium hydroxide at 4 °C, followed by saturation of the alkali-soluble extract with ammonium sulphate gave fractions of mannoprotein, alkali-soluble glucan and alkali-insoluble glucan. Chitin was associated with the alkali-insoluble glucan. The proportions of the different fractions within the walls varied with the species and strain. Mannoprotein comprised between 25% and 34% of the walls, the content of alkali-insoluble glucan ranged from 15% to 48%, and the content of alkali-soluble glucan ranged from 10% to 48%. There was significant variation in the physical appearance of the alkali-soluble glucans and the relative viscosity of suspensions of these glucans. The yeasts could represent novel sources of polysaccharides with industrial and medical applications.
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  • 10
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Overproduction of isoleucine, an essential amino acid, was achieved by amplification of the gene encoding threonine dehydratase, the first enzyme in the threonine to isoleucine pathway, in a Corynebacterium lactofermentum threonine producer. Threonine overproduction was previously achieved with C. lactofermentum ATCC 21799, a lysine-hyperproducing strain, by introduction of plasmid pGC42 containing the Corynebacterium hom dr and thrB genes (encoding homoserine dehydrogenase and homoserine kinase respectively) under separate promoters. The pGC42 derivative, pGC77, also contains ilvA, which encodes threonine dehydratase. In a shake-flask fermentation, strain 21799(pGC77) produced 15 g/l isoleucine, along with small amounts of lysine and glycine. A molar carbon balance indicates that most of the carbon previously converted to threonine, lysine, glycine and isoleucine was incorporated into isoleucine by the new strain. Thus, in our system, simple overexpression of wild-type ilvA sufficed to overcome the effects of feedback inhibition of threonine dehydratase by the end-product, isoleucine.
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