Application of backward differentiation methods to the finite element solution of time-dependent problems

The application of finite element methods to parabolic partial differential equations leads to large linear systems of first-order ordinary differential equations. Very often these systems are stiff and difficulties arise in their numerical solution. We attempt to analyse the problem of how to select numerical methods for the solution of such linear systems.     

Cations (magnesium, potassium, sodium), creatinine, bilirubin, and osmolality of bovine fetal fluids.

Magnesium, potassium, sodium, creatinine and bilirubin concentrations, and osmolality in bovine fetal fluids have been investigated to seek a possible application to the determination of gestation age. Potassium ion concentration during pregnancy decreased in amniotic fluid. Sodium ion concentration and osmolality increased in allantoic fluid during the same period. Creatinine concentration rose throughout pregnancy in both amniotic and allantoic fluids. However, none of these indicators provided a reliable correlation with fetal age as determined by measurements of head circumference.     

Early tissue response to titanium implants inserted in rabbit cortical bone

The tissue response to screw-shaped implants of commercially pure titanium was studied by light microscopy 3–180 days after insertion in the rabbit tibia. The implant site in the tibial metaphysis consisted mainly of cortical bone. Three days after implantation, osteoblasts, producing osteoid, were observed at the endosteal surface and elongated mesenchymal cells were present in the injury area. Some macrophages but rather few other inflammatory cells were identified. Multinuclear giant cells were in direct contact with the implant and formed an almost continuous layer along the surface from the 7th day. The number of giant cells decreased with time and with increased bone-titanium contact. Bone formation was never seen direct on the implant surface but was first observed at day 7 as a woven trabecular bone formed at the endosteal surface and extending towards the implant and as a solitary formation of woven bone close to the implant. The solitary bone matrix served as a base for surface osteoblasts which produced osteoid in a lamellar arrangement. With time the two types of newly formed bone fused and more bone filled the threads and became remodelled by bone remodelling units. Light microscopic morphometry in ground sections demonstrated that the bone/titanium contact and bone area in the threads increased with time up to 6 months after implantation     

Heart failure and echocardiographic changes during long-term follow-up of patients with sick sinus syndrome randomized to single-chamber atrial or ventricular pacing

OBJECTIVE: In the present study, physical and sexual abuse among incarcerated youth were examined with respect to sexual activity, contraceptive use, and pregnancy. METHOD: The self-report survey data were collected from 62 females and 334 males who were incarcerated in Nevada youth correctional facilities in the summer of 1994. Of the males, 46.8% (n = 156) reported a history of physical abuse and 9.9% (n = 33) reported sexual abuse. A surprisingly high 73% (n = 46) of the females reported a history of physical abuse and 68.3% (n = 43) reported sexual abuse. RESULTS: The analyses indicated that females who reported a history of sexual abuse had an earlier mean age of first intercourse than those who reported no sexual abuse. In addition, male and female respondents with a history of physical and/or sexual abuse reported using no method of contraception as compared to youth with no history of abuse. CONCLUSIONS: Implications of these results for detention-based counseling and prevention programming are discussed.     

Interview reliability for assessing mental work demands.

This study presented and evaluated an interview method for the analysis of tasks included in a work situation. What mental demands and possibilities do the work tasks give rise to? When was the work more or less automatic? When was use of active knowledge required? When were problem solving and planning needed? The study included an assessment of the interobserver reliability of the interviews with employees from 5 different careers: bus drivers (n?=?10), home service workers (n?=?32), carpenters (n?=?11), farmers (n?=?14), and teachers (n?=?26). The extent to which this method can be reproduced in studies of different occupations is discussed. The interobserver reliability was good (.75–.82). There is support for the stability and usefulness of the interview for most types of work concerning the 3 categories of mental demands: routine, active knowledge, and problem solving/creativity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Obsessive-compulsive disorder in children and adolescents. Epidemiological and clinical aspects

Obsessive-compulsive disorder (OCD) in children and adolescents is apparently a much more common disorder than previously believed. The literature on OCD in children and adolescents is reviewed, and OCD is described as a severe disorder with a poor prognosis for about half of the patients. The clinical picture seems to be the same across different cultures. The most common symptoms are obsessions about dirt and contamination and washing rituals.     

The apparent diffusion coefficient of water in gray and white matter of the infant brain

PURPOSE: The purpose was to obtain normal values of the apparent diffusion coefficient (ADC) in the infant brain and to compare ADC maps with T1- and T2-weighted images. METHOD: Diffusion was measured in nine infants with an ECG-gated SE sequence compensated for first-order motion. One axial slice at the basal ganglia level was investigated with the diffusion-encoding gradients in the slice-selection direction. RESULTS: On ADC maps, the corpus callosum and the optic radiations appeared dark before the onset of myelination, and the crus posterior of the internal capsule could be visualized before it appeared on T1- or T2-weighted images. In gray and white matter, the mean ADC ranged from 0.95 x 10(-9) to 1.76 x 10(-9) m2/s. In the frontal and occipital white matter, in the genu corporis callosi, and in the lentiform nucleus, the ADC decreased with increasing age. The cortex/white matter ratio of the ADC increased with age and approached 1 at the age of 30 weeks. CONCLUSION: ADC maps add information to the T1 and T2 images about the size and course of unmyelinated as well as myelinated tracts in the immature brain.