Development and fabrication of bismaleimide-graphite composites

The successful fabrication of high temperature resistant composites depends mainly on the processability of the resin binder matrix. For two new bismaleimide type resins the processing of graphite fabric prepregs to composites is described. One resin coded M 751 has to be processed from N-Methylpyrrolidone, the other resin evaluated is a so-called hot melt solvent-less system. Commercial T300/3000 Graphite fabrics were used as reinforcement. The M 751 - Resin is a press grade material and laminates are therefore moulded in high pressure conditions (400 N/sq cm). The solvent-less resin system H 795 is an autoclave grade material and can be cured at 40 N/sq cm. The cure cycles for both the press grade and the autoclave grade material (Fiberite W 143 fabric prepregs) are provided and the mechanical properties of laminates at low (23 C) and high (232 C) temperatures were measured. For comparison, the neat resin flexural properties are also presented. The water absorption for the neat resins and the graphite fabric laminates after a 1000 hour period was evaluated

Integrable impurities for an open fermion chain

Employing the graded versions of the Yang-Baxter equation and the reflection equations, we construct two kinds of integrable impurities for a small-polaron model with general open boundary conditions: (a) we shift the spectral parameter of the local Lax operator at arbitrary sites in the bulk, and (b) we embed the impurity fermion vertex at each boundary of the chain. The Hamiltonians with different types of impurity terms are given explicitly. The Bethe ansatz equations, as well as the eigenvalues of the Hamiltonians, are constructed by means of the quantum inverse scattering method. In addition, we discuss the ground-state properties in the thermodynamic limit.Comment: 20 pages, 4 figure

Pollution effects on asthmatic children in Europe : the PEACE study

This thesis is based upon the 'Pollution Effects on Asthmatic Children in Europe (PEACE)' study. The PEACE study is a multi-centre study of the acute effects of particles with a 50% cut-off aerodynamic diameter of 10 µm (PM 10 ), Black Smoke (BS), SO 2 and NO 2 on respiratory health of children with chronic respiratory symptoms. The aims of the PEACE study were to obtain comparable data on particle concentrations during winter time in various urban and non urban locations in Europe, to assess the relationship between short term fluctuations in air pollution and short term fluctuations in respiratory health in children with chronic respiratory symptoms, to evaluate if medical characteristics of the subjects are related to differences in response to air pollution and to evaluate if the composition of the particles is related to the response to air pollution.The study was conducted in the winter of 1993-1994 by 14 research centres in Europe. 2010 children, divided over 28 panels in urban and suburban locations were followed during at least two months. Exposure to air pollution was monitored on a daily basis. Health status was monitored by daily Peak Expiratory Flow (PEF) measurements and a symptom diary. The association between respiratory health and air pollution levels was calculated with time series analysis, adjusting for time trends, temperature and day of the week.The difference of particle concentrations across countries appeared to be considerably larger than the difference between the urban and suburban location within countries. PM 10 and BS concentrations in the urban area were on average 22% and 43% higher than the corresponding suburban area concentrations respectively. PM 10 concentrations from all Western and Central European locations were significantly correlated in time. No clear associations between PM 10 , BS, SO 2 or NO 2 and morning PEF, evening PEF, prevalence of respiratory symptoms or bronchodilator use could be detected. There were no consistent differences in effect estimates between subgroups based on urban vs. suburban, geographical location or mean levels of PM 10 , BS, SO 2 and NO 2 . None of the predefined potentially more sensitive subgroups showed a consistent association between air pollution, PEF and respiratory symptoms. Daily concentrations of most elemental concentrations in PM 10 were not associated with daily variation in PEF or prevalence of respiratory symptoms or bronchodilator use. However, daily iron and silicon concentrations were related to daily phlegm prevalence.No clear relation could be established between changes in PM 10 , BS, SO 2 or NO 2 and changes in respiratory health. This lack of response is not in agreement with earlier studies with comparable levels of exposure to particulate matter. Concentrations of iron and silicon in PM 10 were associated with prevalence of phlegm and were a better predictor of health effects than PM 10 mass concentrations.</p

Innovations in the Organization of Health Services: Inhibiting vs. Permissive Regulation

This Article concerns the effect of current legal rules upon the possibility of developing non-profit, consumer-sponsored, prepaid comprehensive health-service programs. Concomitantly considered are the effects of existing law upon physician sponsored plans, such as Blue Shield, and upon institutional practice under which non-profit hospitals or other institutions employ salaried physicians. The legal areas covered include: (1) Rules prohibiting the corporate practice of medicine; (2) Enabling acts permitting the operation of prepaid health-service plans; (3) Insurance codes and regulations protecting the public against fraudulent or financially unstable prepayment plans; and (4) Restraint-of-trade rules protecting prepayment plans against harassment and interference

Licensure of Pysicians

This Article examines the most significant features of state medical licensure laws: the scope of mandatory licensure, including the important question of authority for delegations of functions; the nature and role of state licensing agencies; qualifications for licensure candidates, including accreditation of medical schools; license registration and renewal, and reinstatement of lapsed licenses; recognition of licenses of other jurisdictions; and license suspension or revocation, and reinstatement of removed licenses

Axiomatic Bargaining Theory on Opportunity Assignments

This paper discusses issues of axiomatic bargaining problems over opportunity assignments. The fair arbitrator uses the principle of "equal opportunity" for all players to make the recommendation on re- source allocations. A framework in such a context is developed and several classical solutions to standard bargaining problems are reformulated and axiomatically characterized. Working Paper 06-4

Why radiography should no longer be considered a surrogate outcome measure for longitudinal assessment of cartilage in knee osteoarthritis

Imaging of cartilage has traditionally been achieved indirectly with conventional radiography. Loss of joint space width, or 'joint space narrowing', is considered a surrogate marker for cartilage thinning. However, radiography is severely limited by its inability to visualize cartilage, the difficulty of ascertaining the optimum and reproducible positioning of the joint in serial assessments, and the difficulty of grading joint space narrowing visually. With the availability of advanced magnetic resonance imaging (MRI) scanners, new pulse sequences, and imaging techniques, direct visualization of cartilage has become possible. MRI enables visualization not only of cartilage but also of other important features of osteoarthritis simultaneously. 'Pre-radiographic' cartilage changes depicted by MRI can be measured reliably by a semiquantitative or quantitative approach. MRI enables accurate measurement of longitudinal changes in quantitative cartilage morphology in knee osteoarthritis. Moreover, compositional MRI allows imaging of 'pre-morphologic' changes (that is, visualization of subtle intrasubstance matrix changes before any obvious morphologic alterations occur). Detection of joint space narrowing on radiography seems outdated now that it is possible to directly visualize morphologic and pre-morphologic changes of cartilage by using conventional as well as complex MRI techniques