An understanding of the basic concepts of the physics of blood flow is of vital importance to the cardiologist as he or she attempts to utilize new blood flow imaging modalities, such as Doppler ultrasound and nuclear magnetic resonance imaging. Concepts such as the Bernoulli equation and its limitations, the continuity equation and volume flow calculations and the theory of free and confined jets have applications in cardiac blood flow-related problems. For example, mitral regurgitant flow may be treated with the free jet theory. Aortic stenosis results in confined jet flow. It is important that the cardiologist understand the basic principles behind these hydrodynamic concepts so that he or she can use them in appropriate applications. The limitations of the simplification of complex hydrodynamic relations that are used clinically need to be clearly understood so that these simplified principles are not used improperly or used to draw oversimplified conclusions.
While young adult offenders have traditionally been characterized as making a poor adjustment to institutional life, the juvenile incarcerated in an adult facility represents a potentially greater problem. This study examined adjustment after separating the young violent offenders into two groups: those who committed their crimes prior to age 17 and those who committed crimes between 17 and 21. Juvenile inmates were almost twice as likely to be problem inmates, resulting in their not working or earning good-time credit. They were also three times more likely than their slightly older counterparts to be in the most restrictive custody grades. With current legislation enabling the continued incarceration of juveniles in adult facilities, administrators should adopt strategies to manage this special population more effectively.
A number of parolees are returning to the community with programming needs that may not have been addressed during their incarceration; these unmet needs may subsequently affect their successful reintegration into the community. Although there is an increasing female parole population, there has been a paucity of research concerning female parolees. The current study examines the types of needs identified at intake from a sample of 546 female parolees. The results revealed the following. First, if a parolee was employed, had stable living arrangements, and was assessed as needing and receiving some type of drug and/or alcohol program intervention, she was less likely to fail on parole. Second, many of these women were underassessed for having needs for drug and alcohol treatment as well as employment, housing, and other assistance. This underassessment may be because of an increasing emphasis on parole supervision (i.e., custody) rather than treatment in parole agencies.
Even though parole absconders represent one of the largest groups of problem parolees, little has been written about them. Using a large sample of California parolees, the authors examine several variables for their ability to predict absconding and produce an instrument capable of classifying absconders with better than 70% accuracy.
The desire for a low profile mechanical valve with better fluid dynamic performance led to the design and development of the St. Jude Medical bileaflet prosthesis. Comparative in vitro flow studies indicate that it has better pressure drop characteristics than the Björk-Shiley (convexo-concave) and Carpentier-Edwards porcine valves in current clinical use, especially in the small sizes. In the 21 to 27 mm aortic valve size range the St. Jude valve has an average performance index of 0.66, compared with 0.46 and 0.32 for the Björk-Shiley and Carpentier-Edwards valves, respectively. In contrast, the St. Jude valve has larger regurgitant volumes than both the Björk-Shiley and Carpentier-Edwards valves. Velocity measurements with a laser-Doppler anemometer indicate relatively centralized flow with small amounts of turbulence downstream of the St. Jude valve. The flow is unevenly distributed between the central and side orifices. The turbulent shear stresses are, however, large enough to cause sublethal or lethal damage to blood elements. Wall shear stresses are smaller than those measured downstream of the Björk-Shiley valve. Regions of flow separation were observed just downstream from the sewing ring, which could lead to excess tissue growth along the sewing ring. The results of this study indicate that overall in vitro fluid dynamic performance of the St. Jude valve is superior to that of the two other commonly used prostheses.
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