Diesel exhaust particulate induces pulmonary and systemic inflammation in rats without impairing endothelial function ex vivo or in vivo

Background

There is growing evidence that particulate air pollution derived from wood stoves causes acute inflammation in the respiratory system, increases the incidence of asthma and other allergic diseases, and increases respiratory morbidity and mortality. The objective of this study was to evaluate acute respiratory effects from short-term wood smoke exposure in humans. Twenty non-smoking atopic volunteers with normal lung function and without bronchial responsiveness were monitored during three different experimental exposure sessions, aiming at particle concentrations of about 200?μg/m³, 400?μg/m³, and clean air as control exposure. A balanced cross-over design was used and participants were randomly allocated to exposure orders. Particles were generated in a wood-burning facility and added to a full-scale climate chamber where the participants were exposed for 3 hours under controlled environmental conditions. Health effects were evaluated in relation to: peak expiratory flow (PEF), forced expiratory volume in the first second (FEV₁), and forced vital capacity (FVC). Furthermore, the effects were assessed in relation to changes in nasal patency and from markers of airway inflammation: fractional exhaled nitric oxide (FENO), exhaled breath condensate (EBC) and nasal lavage (NAL) samples were collected before, and at various intervals after exposure.

Results

No statistically significant effect of wood smoke exposure was found for lung function, for FENO, for NAL or for the nasal patency. Limited signs of airway inflammation were found in EBC.

Conclusion

In conclusion, short term exposure with wood smoke at a concentration normally found in a residential area with a high density of burning wood stoves causes only mild inflammatory response.     

Smooth upgrade of existing passive optical networks with spectral-shaping line-coding service overlay

A simple and cost-effective upgrade of existing passive optical networks (PONs) is proposed, which realizes service overlay by novel spectral-shaping line codes. A hierarchical coding procedure allows processing simplicity and achieves desired long-term spectral properties. Different code rates are supported, and the spectral shape can be properly tailored to adapt to different systems. The computation can be simplified by quantization of trigonometric functions. DC balance is achieved by passing the dc residual between processing windows. The proposed line codes tend to introduce bit transitions to avoid long consecutive identical bits and facilitate receiver clock recovery. Experiments demonstrate and compare several different optimized line codes. For a specific tolerable interference level, the optimal line code can easily be determined, which maximizes the data throughput. The service overlay using the line-coding technique leaves existing services and field-deployed fibers untouched but fully functional, providing a very flexible and economic way to upgrade existing PONs.     

Oxidative stress and motor neurone disease

The effects of oxidative stress within post mitotic cells such as neurones may be cumulative, and injury by free radical species is a major potential cause of the age-related deterioration in neuronal function seen in several neurodegenerative diseases. There is strong evidence that oxidative stress plays an important role in the pathogenesis of motor neurone disease (MND). Point mutations in the antioxidant enzyme Cu,Zn superoxide dismutase (SOD1) are found in some pedigrees with the familial form of MND. How mutations in this ubiquitous enzyme cause the relatively selective cell death of specific groups of motor neurones is not clear, although a number of hypotheses have been forwarded. These include (1) the formation of hydroxyl radicals, (2) the catalysis of reactions of the nitrogen centred oxidant species peroxynitrite, (3) toxicity of copper or zinc and (4) protein aggregation. Some experimental support for these different hypotheses has been produced by manipulating cells in culture to express the mutant SOD1 proteins and by generating transgenic mice which over-express mutant SOD1. Observations in these model systems are, in some cases at least, supported by observations made on pathological material from patients with similar SOD1 mutations. Furthermore, there are reports of evidence of free radical mediated damage to neurones in the sporadic form of MND. Several lines of evidence suggest that alterations in the glutamatergic neurotransmitter system may also play a key role in the injury to motor neurones in sporadic MND. There are several important subcellular targets, which may be preferentially impaired within motor neurones, including neurofilament proteins and mitochondria. Future research will need to identify the aspects of the molecular and physiological phenotype of human motor neurones that makes them susceptible to degeneration in MND, and to identify those genetic and environmental factors which combine to cause this disease in individuals and in familial pedigrees.     

A numerical study of the residual stress pattern from single shot impacting on a metallic component

Shot peening is a process in which a stream of shot is blasted against an engineering component to generate a high compressive residual stress regime at the surface of the component. This paper describes a 3D finite element dynamic analysis of single shot impacting on a metallic component. The model is first validated against a published numerical study. A parametric study is conducted to investigate the effect of shot diameter, impact velocity, incident angle and component material properties on the resulting residual stress profile. Several meaningful conclusions can be drawn regarding the effect of shot diameter, impact velocity, incident angle and initial yield stress. The effect of strain-hardening parameter is more complex as it depends on the relative magnitude of the strain–hardening yield stress to the initial yield stress and the impact energy.     

The Characterization of Conductive Textile Materials Intended for Radio Frequency Applications

Antennas constructed in part from conductive textile materials (also known as e-textiles) by means of standard textile manufacturing techniques are currently receiving increasing attention from antenna theorists and antenna manufacturers alike. However, due mostly to the unique fabrication methods employed, these novel materials cannot be treated as simple, equivalent substitutes for the more-conventional metallic antennas. Conductive yarns can have considerably less-than-ideal conductivity, and their inhomogeneous internal structure, with features small with respect to the skin depth, can be difficult to analyze directly in terms of conductive-material bulk resistivity. Furthermore, the undulating and sometimes non-planar nature of stitched or woven conductive textile yarns introduces a significant phase delay that must be properly taken into account. This article describes a method to determine the conductivity, sigma , which accurately represents a lossy inhomogeneous textile conductor for a MoM segment having the same radius as the actual conductive yarn. This method has three steps. First, the resistance per unit length of the textile conductor is determined experimentally, in a transmission-line test cell. Next, this measured resistance per unit length is adjusted to account for the nonuniform current distribution across the multiple yarn conductors. Finally, a surface-impedance formulation is employed to derive an equivalent MoM-segment bulk conductivity that accurately represents the measured conductor's performance. Excess phase delay, inherent in textile conductors, is determined by examination of the phase component of the test cell scattering parameter, S₂₁.     

SNS stripper foil development program

When the Spallation Neutron Source (SNS) at the Oak Ridge National Laboratory (ORNL) becomes fully operational it will be the world's highest intensity neutron spallation source. The charge-exchange injection section in the accumulator ring, which strips the injected H⁻ beam to H⁺, requires a stripper foil 260 μg/cm² thick, 12 mm wide, a height of at least 20 mm, and support from just the top edge. The foil will get very hot due to the 1.4 MW, 1 GeV, 60 Hz H⁻ beam that passes through the foil, in addition to the 7–10 foil traversals each circulating proton makes through the foil. The planned upgrade to 3 MW beam power presents an even greater challenge. To meet this challenge a diamond foil development program has been underway at ORNL since 2001. Both microcrystalline and nanocrystalline foils have been developed and tested. In this paper we will discuss the SNS injection process, stripper foil requirements, and results from the diamond foil development and testing program.     

A method to improve the efficiency of CMP process

There are two important things when doing the CMP, one is the high removal rate, and the other is low nonuniformity. The factors, which may effect the result of polishing process, are pressure applied to wafer and the rotation speed of the wafer. In this study, the best polishing pressure distribution was studied. The effect of different boundary conditions between wafer and wafer carrier on the polishing pressure distribution was analyzed. The clearance between pad and wafer also analyzed     

A genetic algorithm-based approach to flexible flow-line schedulingwith variable lot sizes

Genetic algorithms (GAs) have been used widely for such combinatorial optimization problems as the traveling salesman problem (TSP), the quadratic assignment problem (QAP), and job shop scheduling. In all of these problems there is usually a well defined representation which GA's use to solve the problem. We present a novel approach for solving two related problems-lot sizing and sequencing-concurrently using GAs. The essence of our approach lies in the concept of using a unified representation for the information about both the lot sizes and the sequence and enabling GAs to evolve the chromosome by replacing primitive genes with good building blocks. In addition, a simulated annealing procedure is incorporated to further improve the performance. We evaluate the performance of applying the above approach to flexible flow line scheduling with variable lot sizes for an actual manufacturing facility, comparing it to such alternative approaches as pair wise exchange improvement, tabu search, and simulated annealing procedures. The results show the efficacy of this approach for flexible flow line scheduling.