Perceived race-based discrimination, employment status, and job stress in a national sample of black women: implications for health outcomes

This study examined concordance between self-reported drug use and urinalysis data among 341 applicants for methadone treatment in Sydney, Australia. Rates of under-reporting of use of specific drugs were low (0% to 10%). Irregular drug use, short half-life of some abused drugs, and relatively low sensitivity of the TLC assay procedure led to most detected drugs being found in only one of two urine samples collected. Subjects reported having recently used nearly twice as many drugs as were detected in their urine. Agreement (kappa) between self-report and urinalysis results was in the fair to good range for most drugs. None of the six predictors of misreporting examined were found to be of practical value.     

Effects of sleeping in a chemical protective mask on sleep quality and cognitive performance

PURPOSE: We wanted to determine whether sleep is disrupted when soldiers sleep in a new chemical protective mask, the M40. Sleep quantity and quality, extent of protection provided by the mask during sleep, and next day performance were assessed. METHOD: After several days of training, 9 male soldiers slept with and without the M40 mask on four occasions. RESULTS: Soldiers were able to tolerate the mask for most or all of the night. However, sleep, as assessed by wrist-worn activity monitors, was significantly disturbed. Minutes (mean +/- SEM) of waking significantly increased, from 25 +/- 2.1 to 86 +/- 8.5 per night (p < 0.001), and number of awakenings rose from 8 +/- 0.6 to 20 +/- 0.9 (p < 0.0001). Soldiers reported that it took longer and was more difficult to fall asleep when wearing the mask. Errors on a choice reaction time task increased significantly and subjects reported greater fatigue and sleepiness the day after sleeping in the mask. Protection provided by the masks varied substantially among subjects and declined over the course of the study. Some soldiers were protected throughout the night but others were only protected intermittently. CONCLUSION: We conclude that sleeping in the chemical protective mask should only be done when necessary, given the adverse effects on sleep and daytime function, as well as the variability of protection, of the mask.     

Optimization Models for Layout and Pipe Design for Storm Sewer Systems

Optimization models are developed for simultaneously determining the pipe layout and the pipe design for storm sewer systems. The pipe design process includes computation of commercial diameters, slopes, and crown elevations for the storm sewer pipes. The optimization models aim to minimize the total costs of the layout and the pipe design for most of system elements. The optimization models are formulated as a 0–1 Integer Nonlinear Programming problem and solved using the General Algebraic Modeling System without the use of heuristic models which were characteristic of all previous models for the simultaneous determine of the pipe layout and pipe design of sewer networks. The models are based upon two different optimization approaches: (1) considers one or more commercial diameters of pipe connecting two manholes and (2) considers only one commercial diameter in a pipe connecting two manholes. The commercial diameters, pipe slopes, crown elevations, and total costs of the storm sewer system were compared for the two approaches using an example that illustrates the savings in cost by allowing multiple pipe sizes. The two new optimization modeling approaches developed herein can simultaneously determine the minimum cost pipe design (commercial diameters, slopes, and crown elevations) and pipe layout of storm sewer systems and satisfy all design constraints.

     

Mark-Houwink-Sakurada coefficients for conventional poly(methyl methacrylate) in tetrahydrofuran

Summary Intrinsic viscosities [] in tetrahydrofuran (THF) at 30°C are reported for ten narrow molecular weight distribution poly(methyl methacrylate) (PMMA) samples covering nearly two orders of magnitude in molecular weight. By combining the viscosity results with absolute weight-average molecular weights determined via low-angle laser light scattering (LALLS) experiments, we have accurately determined the Mark-Houwink-Sakurada (MHS) parameters for this polymer-solvent pair (K=7.56x10⁵ and a=0.731, when [] is in dL g^-1).     

Synthesis and chain flexibility of poly(cyclohexylethyl methacrylate)

The synthesis and characterization of fractions of poly(cyclohexylethyl methacrylate) (PCHEM) are reported. A combination of low-angle laser light scattering and intrinsic viscosity experiments was employed to estimate the characteristic ratio (C_∞) of this polymer. The value of 10.7 obtained for PCHEM is similar to the value of 11.3 found previously for poly(phenylethyl methacrylate) but is smaller than values measured for poly(cyclohexyl methacrylate) and poly(cyclohexylmethyl methacrylate) (C_∞ = 11.6 and 11.9, respectively). Received: 28 October 1996/Revised: 16 December 1996/Accepted: 19 December 1996     

Legal issues in sharing the benefits of biodiversity prospecting

The National Cancer Institute (NCI) is the US Government's principal agency for research on the prevention, diagnosis and treatment of cancer. A critical component of the Institute's mission is the identification and development of new and promising treatments for cancer and AIDS. For many years these efforts have included a program to investigate natural products for potential new therapeutic agents. In 1986, with the advent of new screening techniques, the National Cancer Institute stepped up its exploration of natural products and began world-wide collections of plants in tropical and subtropical regions. In recognition of the principles of the Biodiversity Treaty, NCI appreciates that continued access to the natural products of these countries depends on the Institute's ability to recognize the contributions of these source countries and their indigenous peoples, and to provide them adequate incentives to conserve their natural resources for the purposes of drug discovery. Accomplishing this goal presented several legal issues for the National Cancer Institute. As an agency of the US government, the NCI has an adjunct statutory mission to facilitate the transfer of technology developed through the Institute's programs into the private sector for further development and commercialization, and NCI operates under a national policy to use the patent system to transfer Federally supported research to the private domestic sector. Reliance on patent law may limit the Institute's ability to recognize the rights of source countries and their indigenous people and provide compensation for their contributions. However, other legal instruments, such as contracts, can serve as interim measures to provide compensation to source countries and indigenous populations. The National Cancer Institute's Letter of Collection agreement (LOC, formerly the "Letter of Intent'), is an example of an alternative means that "fills-in the gaps' created by patent law and through which source countries may share in the benefits of natural product development.     

Improving comparability of hydrogen storage capacities of nanoporous materials

We present results of investigations into improving methods by which gas sorption data are collected and reported. The focus is the accurate comparison of hydrogen storage capacities of different nanoporous materials. The aim is to produce a more rigorous approach to the assessment of the hydrogen storage capacities of different nanoporous materials through formulation of meticulous and systematic data collection routines for production of universally reproducible H₂ isotherms over a wide range of pressure and temperature conditions. Effects of a range of experimental variables are examined and recommendations for the optimisation of data collection routines are given.     

Optimization of Co-content in C14 Laves phase multi-component alloys for NiMH battery application

The structural, electrochemical, and gas phase hydrogen storage properties of predominantly C14 crystalline phase alloys with partial replacement by Co (up to 2.5 at%) are reported. Minor phases, including C15 and cubic TiNi, were found by X-ray diffraction and contributed to the improved hydrogen diffusion through the alloy. The optimal Co-content of between 1.0 and 1.5 at% provides easy activation, high gas phase capacity, and a high discharge capacity. An optimized alloy formula also provided the smallest metallic nickel cluster size embedded in the surface oxide and the largest number of nickel clusters. In sealed cell studies, a Co-content of 1.5% gives the best performance in formation, cycle life, and charge retention, but has worse specific power and low temperature performance than some other compositions. The high-rate dischargeabilities at lower rates were found to be limited by surface reactions, not bulk diffusion.