A rating scale for housing-based health hazards

Objectives

This study investigated the validity and responsiveness of a rating scale designed to assess the housing-based hazards and their relationships to burden of disease symptoms in the building occupants.

Study design

A population-based cross-sectional survey.

Methods

Random-digit dialing with computer-assisted phone interviews was conducted to obtain information from 642 households in the City of Saginaw, Michigan about 71 housing-based hazards, symptoms of 43 diseases often associated with environmental exposures and demographic characteristics. The housing-based hazard index (HHI) was calculated from scores of hazards across the following eight dimensions: structural scale (18 items); moisture/mold scale (8 items), electrical scale (7 items), ventilation and combustion appliances scale (6 items); pest scale (6 items); pets scale (4 items), fire scale (6 items) and lifestyle-associated factors scale (12 items). Each item was assigned a relative score based on the likelihood that the housing occupants would be exposed to the hazard, the potential for serious health impacts, and the reported strength of its association with childhood lead poisoning and respiratory diseases. The psychometric properties of HHI and individual domains (scales) were assessed along with the associations between these indicators and the inventory of disease symptoms.

Results

The reliability of HHI was demonstrated by assessments of its dimensionality and internal consistency. Analysis of the predictive validity and responsiveness indicates that HHI and scores for most of the individual scales can discriminate between households in relation to the burden of reported disease symptoms.

Conclusions

The HHI represents a valid, reasonably reliable, and parsimonious measure of hazards that are congruent with the burden of symptoms generally associated with housing-related diseases.     

Bolted steel slip-critical connections with fillers: I. Performance

This paper reports the results of sixteen experiments of bolted slip-critical connections with fillers. Fifteen of the connections used oversized holes and one connection used standard holes. Such connections with oversized holes are commonly fabricated for use with structures such as long-span trusses, since the use of oversized holes allows erection in-place rather than first assessing fit-up on the ground. Filler plates are used to connect members of different depths or widths. The sixteen experiments reported herein highlight the behavior of bolted steel connections with oversized holes in which fillers are included and are undeveloped, partially developed, or fully developed. Both single-ply and multi-ply fillers are investigated, as are welded developed fillers, and specimens fabricated using either turn-of-the-nut or tension control bolts to pretension the connection. The results augmented with previous literature document the slip and shear strengths of these connections, propose formulas for assessing these strengths for the different conditions investigated, and provide recommendations for design of these types of connections.     

Fatty Acid Synthesis in Glial Cells of the CNS

Fatty acids (FAs) are of crucial importance for brain homeostasis and neural function. Glia cells support the high demand of FAs that the central nervous system (CNS) needs for its proper functioning. Additionally, FAs can modulate inflammation and direct CNS repair, thereby contributing to brain pathologies such Alzheimer’s disease or multiple sclerosis. Intervention strategies targeting FA synthesis in glia represents a potential therapeutic opportunity for several CNS diseases.     

Impact of interferometer optical path difference speed profile on the Fourier-transform-spectrometry-derived spectrum of a telecommunications signal

The impact of the interferometer optical path difference (OPD) speed profile on the spectrum, derived through the use of Fourier-transform spectrometry (FTS), of a synchronous optical network (SONET) signal is found. The SONET signal carries high-speed data traffic. It also may be modulated by low-frequency intensity or frequency modulation. It is found that the SONET header, high-speed data traffic and low-frequency modulation all manifest themselves as artifacts in the FTS-derived spectrum of the SONET signal. It is shown that a nonconstant OPD speed profile can smooth out these artifacts, making it unlikely that they will be mistaken for carrier signal peaks. However, it is found that smoothing out these artifacts lessens the achievable dynamic range of the FTS instrument in the frequency range of interest, the International Telecommunications Union common (C) and long (L) bands.     

Direct observation of the two-phase flow in the air channel of a proton exchange membrane fuel cell and of the effects of a clogging/unclogging sequence on the current density distribution

A small single-channel fuel cell prototype was built with the objective of monitoring the appearance and transport of water droplets in the gas channels in usual operating conditions. It allows the simultaneous observation of droplets and of their local effects on current density. The first results show that the air flow rate seems to control the transition between two different water removal mechanisms: a plug flow when the air stoichiometry is low, with significant disturbances in the local current density, pressure drop and fuel cell performance, and a more conventional flow with steadier removal of smaller droplets when the stoichiometry is higher.     

About internal currents during start-up in proton exchange membrane fuel cell

This paper reports about an experimental and numerical study of the internal currents that occur during fuel cell start-up under open-circuit conditions. The internal currents were measured in a segmented cell specifically designed for this purpose and it was found that they could reach values higher than 1 A cm⁻². They result from the potential that appears at the inlet of the anode compartment while hydrogen pushes oxygen, air, or possibly nitrogen that was introduced for purging water toward the outlet. For a short time, a fraction of the channels is filled with hydrogen while the other part is still occupied by the gas initially present. The model presented in the paper demonstrates that the occurrence of internal currents can be explained mostly by capacitive effects. Carbon oxidation occurs probably simultaneously but its contribution to the internal currents is by all appearances negligible. The model also explains the transient voltage rise (over the steady state open circuit voltage) that is sometimes observed experimentally shortly after the fuel cell start-up.     

Non‐Covalent Immobilization of Rare Earth Heterobimetallic Frameworks and their Reactivity in an Asymmetric Michael Addition

Heterobimetallic Lewis acid catalysts are broadly useful and methods to recycle them have immediate applications. However, their immobilization through covalent binding can be challenging. Non‐covalent immobilization of supported asymmetric catalysts is attractive due to ease of preparation and potential for reversible binding. We report a novel non‐covalent binding strategy for Shibasaki’s REMB framework {RE=rare earth metal; M=Li, Na, K; B=BINOL; RE:M:B=1:3:3, [M₃(sol)_n][(BINOLate)₃RE] } and explore the reactivity of the supported catalyst.