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  • Electronic Resource  (16)
  • Chemistry  (9)
  • Bone density  (4)
  • Life and Medical Sciences  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Predicting vertebral fracture incidence from prevalent fractures and bone density among non-black, osteoporotic women (1993)
    Springer
    Osteoporosis international 3 (1993), S. 120-126 
    Details
    ISSN: 1433-2965
    Keywords: Bone density ; Prospective studies ; Risk factors ; Vertebral fracture incidence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We evaluated the ability of bone density and vertebral fractures at baseline to predict vertebral fracture incidence in a cohort of postmenopausal women with osteoporosis. The study population was 380 postmenopausal women (mean age 65 years) treated for osteoporosis in a randomized, placebo-controlled, clinical trial of the bisphosphonate etidronate at seven geographic centers in the United States. Baseline measurements of bone mineral density were obtained in 1986 by quantitative computed tomography at the spine and dual-photon absorptiometry at the lumbar spine and hip. Vertebral fractures were documented on serial spine radiographs. Proportional hazards models were used to evaluate the ability to predict the risk of subsequent fractures during an average of 2.9 years of follow-up. Presence of one or two fractures increased the rate of new vertebral fractures 7.4-fold (95% confidence interval = 1.0 to 55.9). Additional fractures at baseline further increased the fracture rate. A decrease of 2 standard deviations in spinal bone density by absorptiometry was associated with a 5.8-fold increase in fracture rate (95% confidence interval = 2.9 to 11.6). The lowest and highest quintiles of bone density had absolute fracture rates of 120 and 6 cases per 1000 patient-years, respectively. In general, the simultaneous use of two predictors (bone density and prevalent fractures or two bone density measurements) improved fracture prediction, compared with the use of a single predictor. We conclude that both bone density and prevalent vertebral fractures are strong, complementary predictors of vertebral fracture risk. The results suggest that physicians can use bone density and prevalent vertebral fractures, individually or in combination, as risk factors to identify patients at greatest risk of new fractures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01623272
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  • 2
    Electronic Resource
    Electronic Resource
    Spine fracture risk is predicted by non-spine fractures (1994)
    Springer
    Osteoporosis international 4 (1994), S. 1-5 
    Details
    ISSN: 1433-2965
    Keywords: Bone mass ; Bone density ; Fracture incidence ; Fracture prevalence ; Longitudinal studies ; Risk factors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A prospective cohort study of 1098 postmenopausal Japanese-American women evaluated the relationship between baseline non-spine fractures and new (incident) spine fractures. At the baseline examination in 1981, prevalent non-spine fractures were ascertained by interview, and prevalent spine fractures by radiograph. Bone mass measurements of the distal radius, proximal radius, calcaneus (1981), the lumbar spine (1984) were obtained and repeated at 1- to 2-year intervals. Women with existing non-spine fractures have a threefold greater risk of subsequent spine fractures, independent of bone mass, and independent of the known association between prevalent spine fractures and subsequent spine fractures. Women with both a prevalent non-spine fracture and low bone mass (50th percentile or lower) have an eightfold greater risk of new spine fractures compared with women above the 50th percentile of bone mass and no prevalent fractures. In addition to low bone mass, both prevalent spine fractures and prevalent non-spine fractures are strong risk factors for subsequent spine fracture. These data suggest that not all osteoporotic risk factors are expressed via bone mass, and that other, unmeasured risk factors, such as bone quality defects, may explain these results. In clinical terms, women with both prevalent fractures and low bone mass should be recognized as being at extremely high risk, and treatment potency should be commensurate with this level of risk.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02352253
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  • 3
    Electronic Resource
    Electronic Resource
    Users of low-dose glucocorticoids have increased bone loss rates: A longitudinal study (1995)
    Springer
    Calcified tissue international 57 (1995), S. 115-119 
    Details
    ISSN: 1432-0827
    Keywords: Glucocorticoid ; Bone density ; Bone loss rates ; Longitudinal study
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Although high doses of glucocorticoids are believed to cause bone loss, the effects of low glucocorticoid doses are still controversial. Our study examined the effects of low-dose glucocorticoids on the rate of bone loss at three appendicular bone sites. The study population was a cohort of elderly Japanese-Americans, 1094 women and 1378 men. The women were all postmenopausal. At the baseline examination the mean age of the women was 64 years (range 45–81), and the mean age of the men was 68 years (range 61–82). Glucocorticoid users (19 women and 21 men) had used oral systemic or inhaled glucocorticoids on a regular schedule for more than 1 month (mean use was 2.1 years for the women and 1.9 years for the men). The most common dose was equivalent to 5 mg/day of prednisone; fewer than 15% of users had taken doses equivalent to 10 mg/day or more. Changes in bone mass at the calcaneus, distal radius, and proximal radius were documented using bone densitometry at 1 to 2-year intervals over an 8-year period. The initial bone mass of the glucocorticoid users and controls was similar at the baseline examination. The subsequent loss rates among females during glucocorticoid use, however, were approximately double that of the controls. Among males, bone loss rates during glucocorticoid use were 2–3 times that of controls for the calcaneus and radius sites. The differences between glucocorticoid users and controls persisted after adjusting for confounding variables such as age and use of thiazides and estrogens. We conclude that users of low-dose glucocorticoids have increased rates of bone loss at appendicular sites among both elderly women and men.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00298431
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  • 4
    Electronic Resource
    Electronic Resource
    When should bone density measurements be repeated? (1994)
    Springer
    Calcified tissue international 55 (1994), S. 243-248 
    Details
    ISSN: 1432-0827
    Keywords: Osteoporosis ; Bone density ; Longitudinal studies ; Statistical models ; Decision models
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract We calculated how long to wait before repeating bone mineral density (BMD) measurements to reassess fracture risk. Correlation results from serial measurements of 495 postmenopausal Japanese-American women were used to estimate 95% confidence intervals (CI) for future BMD. After 7 years of follow-up, BMD correlations with the initial measurement ranged between 0.81 and 0.94, depending on age group and measurement site. In this analysis, the period between measurements was defined as the time required for the lower 95% CI to fall below the BMD value corresponding to doubling of fracture risk. Progressive bone loss causes fracture risk to double after 10 years, on average. However, the 95% CIs indicate that a second BMD measurement will detect risk doubling after only 2 or 3 years for some women. For untreated, early postmenopausal women, the period between measurements was approximately 2–5 years for the radius and 4–6 years for the calcaneus, depending on the initial BMD level. The period was approximately 1 year longer for women age 60 and older. Treatments that halve the bone loss rate would increase the period by 1–3 years. In the absence of a second measurement of BMD, the CI will continue to expand with time, corresponding to a wider range in risk between individuals, and a greater proportion of women will be at increased fracture risk. Obtaining a second BMD measurement pinpoints the patient's status within the precision of the measurement. We conclude that repeated BMD measurements will provide a more accurate estimate of fracture risk than a single, baseline measurement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00310399
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  • 5
    Electronic Resource
    Electronic Resource
    Mean weights of chick embryos correlated with the stages of Hamburger and Hamilton (1968)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 124 (1968), S. 79-82 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A total of 1125 normal chick embryos, representing 25 each of the 45 stages of Hamburger and Hamilton, were removed, fixed in Bouin's solution, stored in 70% ethanol and weighed with a semi-micro analytical balance. Entire blastoderms of stages 1-8 were weighed, whereas only embryos-proper were weighed in stages 9-45. As a consequence, results constituted two groups, each of which showed a geometric rate of growth marked only by minor deviations which were related to specific events of normal growth and development.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051240105
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  • 6
    Electronic Resource
    Electronic Resource
    Gross error detection when variance-covariance matrices are unknown (1993)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 39 (1993), S. 1335-1341 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Equations introduced here identify measurement biases and process leaks, when gross errors exist in measured process variables and the variance-covariance matrix of the measurements, Σ, is unknown. Σ is estimated by the sample variance, S, using process data.For an unknown Σ, the global test statistic is the well-known Hotelling T2 statistic. Its power function has a noncentral F-distribution. For component tests used for specific identification of measurement biases and nodal leaks, two tests are presented with Σ unknown. The first test is independent of the number of component tests, k, and is given by a statistic with an F-distribution. The second test depends on k and has a student t-distribution. The power functions for both component tests are provided. Process examples and a Monte Carlo simulation study presented demonstrate the use and performance of these statistical equations in identifying biases and process leaks.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690390810
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  • 7
    Electronic Resource
    Electronic Resource
    Unbiased estimation of gross errors in process measurements (1992)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 38 (1992), S. 563-572 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new approach to gross error detection provides unbiased estimates and 100(1-α)% simultaneous confidence intervals of process variables when biased process measurements and process leaks exist. Presented in this article are estimation equations for process variables, as well as equations that help identify biased measurements and process leaks. These equations include the power function for a global test, and two types of α-level component tests and their power functions. Important strengths and weaknesses of this approach are compared to those of the serial compensation strategy, in particular, by varying the significance level (α), the variance-covariance matrix (Σ), the size of measurement bias (δ), the number of biased variables, and the sample size (N). Accuracy of δ estimation and performance in detecting the presence of process leaks (γ) are also evaluated and compared. The proposed approach has unique features that can provide a basis for improving the reconciliation of variables in process operations.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690380410
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  • 8
    Electronic Resource
    Electronic Resource
    Fractionating condensation and evaporation in plate-fin devices (1986)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 32 (1986), S. 1116-1124 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A model that describes fractionation with condensation and evaporation in a plate-fin device has been formulated. It is capable of evaluating profiles of composition, temperature, and flow rate for both liquid and vapor streams in an extended surface device. The device may be adiabatic or nonadiabatic and the surface may be incompletely wetted. Compared to experimental measurements, the model predictions showed ± 1 number of transfer unit deviation along the length of the device. The predictions of the top and bottom flow rate ratio showed a 5-10% deviation for adiabatic and condensation runs and a 25% deviation for evaporation runs.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690320708
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  • 9
    Electronic Resource
    Electronic Resource
    Solid-liquid-vapor phase behavior of the methane-carbon dioxide system (1962)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 8 (1962), S. 537-539 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The phase behavior of the methane-carbon dioxide system has been determined experimentally along the solid-liquid-vapor locus. Pressure-temperature measurements were made along this locus from the triple point of carbon dioxide to -284°F. Compositions of the vapor phase along the solid-liquid-vapor locus were determined with sampling techniques over a composition range of 0.1 to 12% carbon dioxide. Liquid-phase compositions were obtained from crystal-point determinations on eleven methane-carbon dioxide mixtures ranging from 0.16 to 20% carbon dioxide.With the pressure-temperature for the solid-liquid-vapor locus as the termination locus of the dew and bubble data of Donnelly and Katz (2), consistent liquid- and vapor-phase compositions were obtained over the remaining concentration range.Changes in the pressure-temperature relationship of the solid-liquid-vapor locus caused by using a methane stock containing 0.56 mole % nitrogen are also reported.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690080423
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  • 10
    Electronic Resource
    Electronic Resource
    Fractionation with condensation and evaporation in wetted-wall columnsThis paper is not to be reproduced or published in any form without the written permission of the authors. J. F. Davis is now with the Department of Chemical Engineering, The Ohio State University. (1984)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 30 (1984), S. 328-338 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A model is presented to describe the behavior of falling film fractionators with evaporation or condensation. Experimental measurements of vapor composition, vapor temperature and wall temperature profiles were made. Close agreement suggests that the model is applicable to both adiabatic and nonadiabatic conditions.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690300223
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