Effectiveness of portable HEPA air cleaners on reducing indoor PM2.5 and NH3 in an agricultural cohort of children with asthma: A randomized intervention trial

We conducted a randomized trial of portable HEPA air cleaners with pre-filters designed to also reduce NH₃ in non-smoking homes of children age 6-12 with asthma in Yakima Valley (Washington, USA). Participants were recruited through the Yakima Valley Farm Workers Clinic asthma education program. All participants received education on home triggers while intervention families additionally received two HEPA cleaners (child's sleeping area, main living area). Fourteen-day integrated samples of PM_2.5 and NH₃ were measured at baseline and one-year follow-up. We fit ANCOVA models to compare follow-up concentrations in HEPA vs control homes, adjusting for baseline concentrations. Seventy-one households (36 HEPA, 35 control) completed the study. Most were single-family homes, with electric heat and stove, A/C, dogs/cats, and mean (SD) 5.3 (1.8) occupants. In the sleeping area, baseline geometric mean (GSD) PM_2.5 was 10.7 (2.3) μg/m³ (HEPA) vs 11.2 (1.9) μg/m³ (control); in the living area, it was 12.5 (2.3) μg/m³ (HEPA) vs 13.6 (1.9) μg/m³ (control). Baseline sleeping area NH₃ was 62.4 (1.6) μg/m³ (HEPA) vs 65.2 (1.8) μg/m³ (control). At follow-up, HEPA families had 60% (95% CI, 41%-72%; p < .0001) and 42% (19%-58%; p = .002) lower sleeping and living area PM_2.5, respectively, consistent with prior studies. NH₃ reductions were not observed.     

Materials systems for interleave toughening in polymer composites

We review the literature describing the use of interleaves to increase interlaminar fracture toughness in fibre-reinforced polymer composites and hence to improve damage tolerance. From an analysis of data provided in the literature from the use of microfibre and nanofibre interleaves, we show that the performance of these widely researched systems is clearly differentiated when plotted against the mean coverage of the interleaf. Using a simple analysis, we suggest that this can be attributed to the influence of their porous architectures on the infusion of resin. We show also that the superior toughening performance of microfibre interleaves is only weakly influenced by the choice of fibre. We find also that the inclusion of carbon nanotubes within interleaves to deliver multifunctional composites can be optimised by using a hybrid system with microfibres.

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Elastic and inelastic analysis for weld failure prediction of two adjacent steel buildings

Two adjacent buildings near the epicenter of the January 17th Northridge earthquake, one with weld fractures and one without weld fractures, are considered in this research. Both buildings are six stories in height, and their primary lateral force resisting system comprises special moment resisting frames above grade. The buildings considered are referred to herein as the East Building and the West Building. Two basic types of computer studies were performed. One was an elastic 3-D analysis using SAP90, and the other an inelastic 2-D analysis using DRAIN-2DX. Three different models were, created for the elastic analysis. Two for the East Building, designated the ‘benchmark model’, and the ‘probable model’, and one for the West Building, designated the ‘West Building model’. Two different models were created for the inelastic analysis only for the East Building, also called the benchmark model and the probable model. The East Building was unoccupied at the time of the earthquake, hence two models were created for this building. The benchmark model is representative of the design state of the building, while the probable model is representative of the state of the building at the time of the earthquake. The West Building, which was fully occupied at the time of the earthquake, was modeled similarly to the benchmark. Elastic and inelastic studies were performed on these models to determine if a correlation exists between analysis and observed behavior. The findings from the analysis showed no damage to the West Building with possible damage to the East Building. This result is corroborated by the damage survey.     

To boldly go: an occam-π mission to engineer emergence

Future systems will be too complex to design and implement explicitly. Instead, we will have to learn to engineer complex behaviours indirectly: through the discovery and application of local rules of behaviour, applied to simple process components, from which desired behaviours predictably emerge through dynamic interactions between massive numbers of instances. This paper describes a process-oriented architecture for fine-grained concurrent systems that enables experiments with such indirect engineering. Examples are presented showing the differing complex behaviours that can arise from minor (non-linear) adjustments to low-level parameters, the difficulties in suppressing the emergence of unwanted (bad) behaviour, the unexpected relationships between apparently unrelated physical phenomena (shown up by their separate emergence from the same primordial process swamp) and the ability to explore and engineer completely new physics (such as force fields) by their emergence from low-level process interactions whose mechanisms can only be imagined, but not built, at the current time.     

The drying shrinkage of cellulosic fibres and isotropic paper sheets

We present theory for the shrinkage on drying of the cross-sectional area of cellulosic fibres and show that this depends on their initial moisture content only. For the linear shrinkage of cross-sectional dimensions, an additional parameter is required, which we estimate from comparison of the theory with experimental data from the literature. We proceed to combine our model of fibre shrinkage with probabilistic theory for fibre contacts in random fibrous networks to obtain a model for the unrestrained shrinkage of isotropic paper sheets. The expression obtained depends only on the moisture content of fibres and the extent of inter-fibre contact and exhibits good agreement with experimental data for laboratory-formed paper sheets. The results have relevance to the commercial manufacture of paper and potential for application to the study of cellulose nano-composites.     

Drug use and validity of substance use self-reports in veterans seeking help for posttraumatic stress disorder.

The present study assessed drug use and the validity of self–reports of substance use among help–seeking veterans referred to a specialty clinic for the assessment of posttraumatic stress disorder (PTSD). Patients (n?=?341) were asked to provide a urine sample for use in drug screening as part of an evaluation of PTSD. Self–reports of substance use were compared with same–day supervised urine samples for 317 patients who volunteered to participate in a drug screening. Results suggested that self–reports were generally quite valid. Only 8% of the cases involved patients not reporting substance use detected by urine screens. A total of 42% of the participants were identified as using drugs of abuse (excluding alcohol) through self–report and urine drug screens. Among participants using drugs, PTSD diagnosis was significantly associated with greater marijuana and depressant use as compared with stimulant (cocaine and amphetamines) use. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spread-spectrum optical fibre network based on pulsed coherent correlation

Coherent recombination of a series of pulses derived from a single laser pulse by matched filtering, using optical ladder networks is shown to result in a highly single-peaked correlation function. The technique may be used in a local area network based on a star topology when this coherent correlation is generated using a low coherence source. This provides a more practical but equally powerful alternative to other current proposals.<>     

Alcohol consumption by young actively growing rats: a study of cortical bone histomorphometry and mechanical properties

Alcohol consumption by young actively growing rats has been previously demonstrated to decrease cortical and cancellous bone density, to reduce trabecular bone volume, and to inhibit bone growth at the epiphyseal growth plate. This study addresses the action of alcohol on cortical bone growth using histomorphometric techniques and on mechanical properties by three-point bending. Four-week-old, female Sprague-Dawley rats were divided into three groups. Alcohol-treated animals were fed a modified Lieber-DeCarli diet ad libitum containing 35% ethanol-derived calories, whereas the pair-fed animals (weight-matched to ethanol rats) received an isocaloric liquid diet in which maltose-dextrin-substituted calories were supplied by ethanol. Chow animals were fed a standard rat chow ad libitum. Femora were removed for analysis after 2, 4, 6, or 8 weeks on the diets. Cortical bone area, bone formation rates, and mineral apposition rates were reduced in the alcohol-fed animals. Bone stiffness, strength, and energy absorbed to fracture were significantly lower in the alcohol-fed animals. This distinctive alcohol effect was revealed to be caused by lower quality bone tissue as reflected by lower elastic moduli and yield strengths.