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  • 1
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A rapid, semiautomated system to quantitate and analyze leukocyte shape and locomotion was developed. Video images of moving leukocytes were obtained using a Vidicon camera mounted on a Nikon phase microscope. The video signal was either inputted directly, or indirectly via a video cassette recorder, to a Datacube video analog-digital, digital-analog converter. A Digital Equipment Corporation LSI 11/23 computer using the RT-11/TSX-Plus operating system and computer programs written in FORTRAN and MARCO assembly language permitted image segmentation, image display, and calculation of position, speed, direction of movement and orientation of each leukocyte at 10 s intervals. These data were stored on a winchester disk for subsequent evaluation of the leukocyte orientation, speed and direction of movement using statistical and graphical methods. The reproducibility of measurements made with the video system was tested by comparison with manual measurements; a correlation coefficient of 0.998 was obtained for the two methods. Rates of chemokinesis were then determined for unstimulated and chemokinetically stimulated polymorphonuclear leukocytes (PMNs) and found to average 12.8 μm/min and 18.1 μm/min, respectively. The high speed, ease of data analysis, and potential for multiparameter evaluation makes this system useful for directly evaluating leukocyte locomotion.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1433-2965
    Keywords: Key words:Child abuse – Computed tomography (CT) bone density – Osteogenesis imperfecta type I
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract: The objectives of this study were (1) to determine whether there are differences in bone density in children versus adults with osteogenesis imperfecta type I (OI-type I) using computed tomography (CT) bone density measurements, (2) to determine whether there are differences in bone density between normal infants and infants with OI-type I using CT bone density measurements and (3) to determine whether CT bone density measurements could be helpful in investigating the infant with unexplained fractures. CT bone density measurements determine both the cortical bone density (CBD) and the trabecular bone density (TBD). CT bone density was determined using the OsteoQuant in 14 individuals with OI-type I who ranged in ages from 8 months to 45 years. The control groups consisted of over 1000 normal individuals, mostly adults, and included 7 normal infants who ranged in age from 10 months to 27 months. One of the individuals with OI-type I was a 4-month-old infant with multiple, unexplained fractures who had no other features of OI-type I and whose parents were accused of child abuse. Infants and children with OI-type I had low CBD and low TBD compared with normal controls, whereas adults with OI-type I had low TBD and high CBD when compared with controls. The one infant with multiple unexplained fractures and no other features of OI-type I had a bone density profile suggesting OI-type I with a low TBD and low CBD. Subsequent collagen analysis showed biochemical evidence of OI-type I. Individuals with OI-type I have abnormal CT bone density profiles that evolve over time from a low CBD and low TBD during infancy and childhood to a high CBD and low TBD during adulthood. This may explain the decreased frequency of fractures in individuals with OI-type I in adulthood compared with childhood. Individuals with OI-type I can present with only multiple unexplained fractures and have no other clinical features to strongly suggest the diagnosis. CT bone density measurements can be helpful in these atypical cases of OI-type I and should be considered in the investigation of the infant with unexplained fractures to help distinguish intrinsic bone disease from child abuse.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1420-9136
    Keywords: Pore fluid chemistry ; Stable sliding ; Fault gouge
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Single-cycle and multiple-cycle frictional-sliding experiments were employed to evaluate the effects of pore fluid environments on yield strength, frictional-sliding dynamics, and gouge production and morphology. Circular right cylinders cored from Berea sandstone sawcut at 35° to the axes were saturated in water, an inorganic brine, and various anionic, cationic, and nonionic aqueous surface-active agents. Samples were deformed under an effective confining pressure of 50 MPa and an axial strain rate of 6×10−5 sec−1 until a 2% axial strain beyond yield (defined as the onset of sliding) was achieved. All samples were displaced by stable sliding. In the single-cycle tests the unsaturated and water-saturated samples displayed small stress peaks at yield. During stable sliding samples saturated with DTAB and SDS displayed slight increases in differential stress and statistically significant higher frictional coefficients than other environments (including water) but were very similar in behavior to dry, unsaturated samples. In the multiple-cycle tests, samples were loaded to 2% strain beyond yield and unloaded to a differential stress of approximately 5–10 MPa a total of four times. These results further suggest that DTAB exerts a ‘strengthening’ effect on the sandstone relative to water which, to a limiting value, increased with displacement. The DTAB and SDS environments also produced a coarser grain-size distribution in the gouge relative to gouge produced in the other environments. Investigation of the gouge by scanning electron microscope revealed that these larger ‘grains’ were composed of dense, apparently cemented aggregates of ultrafine, platy quartz particles.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract Four heterotrophic nitrifying bacteria—two Bacillus spp., an unidentified gram-positive rod and a gram-negative rod tentatively identified as a Pseudomonas sp.—were isolated from surficial sediments from Boston Harbor, Massachusetts. None of the organisms produced a detectable level of NO 3 − . Nanomolar levels of tributyltin (TBT) and its degradation products dibutyltin (DBT) and monobutyltin (MBT) were examined for their effects on growth, NH 4 + - uptake and N-oxidation by the organisms. TBT inhibited growth of all four isolates. DBT inhibited growth of Bacillus sp. SC-2 and the unidentified gram-positive rod. Growth of the Pseudomonas sp. was inhibited by exposure to 100 nM MBT. NH 4 + uptake was inhibited, even by butyltin species that did not inhibit growth. Free NH2OH production and NO 2 − production were inhibited by TBT but varied from being inhibited to being stimulated with different DBT or MBT exposure regimes. Nitrite production was affected differently from free NH2OH production for Bacillus sp. SC-2 and the unidentified rod. DBT appears to be particularly toxic to NH2OH oxidation by these four organisms. At the concentration used, TBT was more toxic than DBT or MBT. The results suggest that butyltins have the potential to affect nitrification by heterotrophic bacteria in the aquatic environment at nanomolar levels and that degradation of TBT to DBT and MBT does not necessary detoxify it.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Radiophysics and quantum electronics 32 (1989), S. 199-207 
    ISSN: 1573-9120
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1573-9120
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1439-0426
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: A laboratory experiment was carried out to quantify and compare the physical damage (measured as scale loss), recovery and survival of two size categories [small: 48–85 mm total length (TL); large: 78–148 mm TL] of 0-group mulloway, Argyrosomus japonicus, after simulated escape through square-shaped mesh (bar length of 21.5 mm). Regardless of their size, fish that were fatigued to exhaustion and forced through square meshes sustained significantly more (i.e. 〉1.8 times) scale loss than did control fish that were only fatigued. However, the total scale loss incurred was 〈5% and significantly improved 7 days after treatment. Survival rates over a 2-week observation period were 100 and 〉97% for treatment and control fish, respectively. The results support the utility of square mesh for reducing the prawn-trawl fishing mortality of unwanted bycatch.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-0827
    Keywords: Key words: Temporary brittle bone disease — Child abuse — CT bone density — Mechanostat — Mechanical loading — Fetal movement — Osteopenia.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. Infants who present with multiple unexplained fractures pose a difficult diagnostic dilemma of child abuse versus intrinsic bone disease. Temporary brittle bone disease is a recently described disease characterized by a transient bone weakness in the first year of life which presents with multiple, unexplained fractures that can be confused with child abuse. The purpose of this study was to determine if there are common, historical features in infants with unexplained fractures that might suggest a basis for the fractures, and to determine if bone density measurements might indicate that such infants have low bone density. Medical records were reviewed in 33 infants who were referred for consultation for multiple unexplained fractures in which the parents and other caregivers denied wrongdoing. In 9 of the infants, radiographic absorptiometry and/or computed tomography bone density studies were performed. In 26 of these infants the diagnosis of temporary brittle bone disease was made. A normal collagen test was found in 17 of the 26 infants studied; 9 infants did not have a collagen test because the diagnosis of osteogenesis imperfecta was considered highly unlikely. In 25 of them there was a history of decreased fetal movement and/or intrauterine confinement. Bone density, as judged by plain X-ray films, was normal in all 26 cases, but when formally measured by radiographic absorptiometry or computed tomography, the bone density measurements were low in 8 of the 9 infants studied. These findings implicate decreased fetal movement and intrauterine confinement as contributing factors to temporary brittle bone disease and suggest that normal, unconstrained fetal movement during pregnancy is important for normal fetal bone formation. These findings support the model that bone formation and strength are dependent on the mechanical load placed on the bone. The results also demonstrate the usefulness of bone density measurements in evaluating the infant with multiple unexplained fractures to help distinguish nonaccidental injury from intrinsic bone disease.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-2099
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Summary These studies have addressed firstly the effect of single small doses of x-rays upon murine hematopoietic stem cells to obtain a better estimate of theD q . It is small, of the order of 20 rad. Secondly, a dose fractionation schedule that does not kill or perturb the kinetics of hemopoietic cell proliferation was sought in order to investigate the leukemogenic potential of low level radiation upon an unperturbed hemopoietic system. Doses used by others in past radiation leukemogenesis studies clearly perturb hemopoiesis and kill a detectable fraction of stem cells. The studies reported herein show that 1.25 rad every day decrease the CFU-S content of bone marrow by the time 80 rads are accumulated. Higher daily doses as used in published studies on radiation leukemogenesis produce greater effects. Studies on the effect of 0.5, 1.0, 2.0, and 3.0 rad 3 times per week are under way. Two rad 3 times per week produced a modest decrease in CFU-S content of bone marrow after an accumulation of 68 rad. With 3.0 rad 3 times per week an accumulation of 102 rad produced a significant decrease in CFU-S content of bone marrow. Dose fractionation at 0.5 and 1.0 rad 3 times per week has not produced a CFU-S depression after accumulation of 17 and 34 rad. Radiation leukemogenesis studies published to date have utilized single doses and chronic exposure schedules that probably have significantly perturbed the kinetics of hematopoietic stem cells. Whether radiation will produce leukemia in animal models with dose schedules that do not perturb kinetics of hematopoietic stem cells remains to be seen.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Industrial & engineering chemistry 41 (1949), S. 1757-1761 
    ISSN: 1520-5045
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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