Photoluminescent properties of flexible PVC compounds and their interpretation for performance analysis of automotive exterior parts

Study of fluorescence emission from flexible PVC‐based formulations, colored by exposure to road asphalt or degraded thermally or by UV aging, shows that fluorescent species are formed during the interaction of PVC with road asphalt. For the conditions found in exterior automotive applications, no other known degradation causes development of fluorescence. Flexible PVC‐based formulations discolored by asphalt staining or degraded thermally at moderate temperatures bleach completely under conditions of natural or artificial weathering. A simple technique, using visually observed photoluminescence and photobleaching, can thus identify photoactive groups formed during the interaction of PVC with road asphalt. Application of this test method will allow selective improvement of failed asphalt resistance without treating the “overall” stability of a compound.     

Peripheral osteopenia in adult patients with insulin-dependent diabetes mellitus

Alterations in bone metabolism in diabetes mellitus is a topic of special interest. Bone blood flow is increased in the distal limb of diabetic patients, which is believed to increase osteoclastic activity. We measure bone mineral density using dual-photon absorptiometry in the distal lower limb, the femoral neck, and the lumbar spine in 41 IDDM patients and in 30 control persons. In the diabetic group there was a 10% reduction of bone mineral density in the femoral neck (p < 0.01) and a 12% reduction in the distal limb (p < 0.001) compared with the control group. No significant difference was found in the lumbar spine (p = 0.22). Our data yield incidence for peripheral osteopenia in IDDM-patients, independent of any systemic bone disease such as osteoporosis. A link between decreased bone mineral density and diabetic neuropathy has been observed for the femoral neck (p < 0.001), but not for the distal limb or axial skeleton. Whether there is a common aetiological link or a casual connection between diabetic neuropathy and bone mineral density has still to be determined.     

Numerical simulations of scattering in a two-photon optical data storage system

Scattering effects in a two-photon optical data storage system are numerically studied. Surface scattering analysis with a scalar, beam propagation model is performed. We analyze the problem by modeling scattering from randomly varying surfaces and also by Fourier surface decomposition. Scattering induced by propagation through multiple pages of randomly recorded data marks is also studied with a hybrid finite-difference-time-domain/angular-spectrum model. Both surface and bulk scattering are shown to influence the spatial properties of the optical beam. Results and some possible implications are presented.     

Comparison of paper-and-pencil versus Web administration of the Youth Risk Behavior Survey (YRBS): Participation,data quality,and perceived privacy and anonymity

The Youth Risk Behavior Surveillance System (YRBSS) monitors priority health-risk behaviors among US high school students. To better understand the ramifications of changing the YRBSS from paper-and-pencil to Web administration, in 2008 the Centers for Disease Control and Prevention conducted a study comparing these two modes of administration. Eighty-five schools in 15 states agreed to participate in the study. Within each participating school, four classrooms of students in grades 9 or 10 were randomly assigned to complete the Youth Risk Behavior Survey questionnaire in one of four conditions (in-class paper-and-pencil, in-class Web without programmed skip patterns, in-class Web with programmed skip patterns, and “on your own” Web without programmed skip patterns). Findings included less missing data for the paper-and-pencil condition (1.5% vs. 5.3%, 4.4%, 6.4%; p < .001), less perceived privacy and anonymity among respondents for the in-class Web conditions, and a lower response rate for the “on your own” Web condition than for in-class administration by either mode (28.0% vs. 91.2%, 90.1%, 91.4%; p < .001). Although Web administration might be useful for some surveys, these findings do not favor the use of a Web survey for the YRBSS.     

Sexual behavior among U.S. high school students, 1990-1995

CONTEXT: High rates of unintended pregnancy and sexually transmitted diseases (STDs), including HIV infection, among adolescents are major public health concerns that have created interest in trends in teenage sexual activity. METHODS: Nationally representative data from Youth Risk Behavior Surveys conducted in 1990, 1991, 1993 and 1995 are used to examine levels of sexual experience, age at first intercourse, current sexual activity and condom use at last intercourse among students in grades 9-12. RESULTS: The proportion of students who reported being sexually experienced remained at 53-54% from 1990 through 1995, while the percentage of sexually active students who used condoms at last intercourse rose from 46% to 54% between 1991 and 1995. Black students were more likely than white students to report being sexually experienced, being currently sexually active and having had four or more lifetime sexual partners; black students also reported a significantly younger age at first intercourse. Gender differences in sexual behavior were found more frequently among black students than among white or Hispanic students. CONCLUSIONS: Although levels of sexual experience for high school students in the United States have not risen during the 1990s, a very high percentage of students continue to be at risk for unintended pregnancy and STDs, including HIV infection.     

STARFIRE,a commercial tokamak power plant design

STARFIRE is a design for a conceptual commercial tokamak electrical power plant based on the deuterium/tritium/lithium fuel cycle. In addition to the goal of being technologically credible, the design incorporates safety and environmental considerations. STARFIRE is considered to be the tenth in a series of commercial fusion power plants.STARFIRE has a 7-m major radius reactor producing 1200 MW of net electrical power from 4000 MW of thermal power, with an average neutron wall load of 3.6 MW/m². The aspect ratio is 3.6 and a D-shaped plasma with a height-to-width ratio of 1.6 and average toroidal beta of 0.067 is used. The maximum magnetic field is 11T. Availability goals have been set at 85% for the reactor and 75% for the complete plant including the reactor.The major features for STARFIRE include a steady-state operating mode based on a continuous rf lower-hybrid current drive and auxiliary heating, solid tritium breeder material, pressurized water cooling, limiter/vacuum for impurity control, most superconducting EF coils outside the TF superconducting coils, fully remote maintenance, and a low-activation shield.     

Changes in HIV-related information sources, instruction, knowledge, and behaviors among US high school students, 1989 and 1990

The diagnostic values of aminoterminal propeptide of type III procollagen and hyaluronan serum levels were compared as markers of liver fibrosis in two chronic liver diseases of different etiologies and pathophysiologies, namely primary biliary cirrhosis and chronic viral hepatitis C. The results were analysed in terms of the histological extent of fibrosis. Both serum procollagen-III peptide and hyaluronan were elevated in patients with primary biliary cirrhosis and chronic viral hepatitis C (p < 0.0001) relative to control values. A positive correlation was found between serum procollagen-III peptide levels and the histological grade of fibrosis in primary biliary cirrhosis (p < 0.001) but not in chronic viral hepatitis C, while a strong correlation was found between serum hyaluronan levels and histological fibrosis in both primary biliary cirrhosis and chronic viral hepatitis C (p < 0.001), independent of age. These results suggest that, in chronic liver diseases, serum hyaluronan levels could be an important indicator of the extent of fibrosis and should be assayed to monitor the response to treatment in controlled clinical trials.     

Integrating algorithm animation into a learning environment

Algorithm animation would seem to be a useful tool for teaching algorithms. However, previous empirical studies of using algorithm animation have produced mixed results. This paper presents an empirical study in which the subjects programmed the algorithm which they had seen animated. The results of the experiment indicate that combining the animation with the implementation of the algorithm was an effective way to teach the animation, and also produced transfer effects for general recursion problems.     

Heating mechanisms in a near-field optical system

A finite-difference-time-domain and two finite-difference-thermal models are used to study various heating mechanisms in a near-field optical system. It is shown that the dominant mechanism of sample heating occurs from optical power that is transferred from the probe to a metallic thin-film sample. The optical power is absorbed in the sample and converted to heat. The effects of thermal radiation from the probe 's coating and thermal conduction between the probe and the sample are found to be negligible. In a two-dimensional waveguide with TE polarization, most of the optical power is transferred directly from the aperture to the sample. In a two-dimensional waveguide with TM polarization, there is significant optical power transfer between the probe 's aluminum coating and the sample. The power transfer results in a wider thermal distribution with TM polarization than with TE polarization. Using computed temperature distributions in a Co -Pt film, we predict the relative size of thermally written marks in a three-dimensional geometry. The predicted mark size shows a 30 % asymmetry that is due to polarization effects.