Thermal and bias cycling stabilizes planar silicon devices

Terminal burn-in or baking step time in the processing of planar silicon devices is extended to reduce their inversion tendencies. The collector-base junction of the device is also cyclically biased during the burn-in

Automated Design of Tissue Engineering Scaffolds by Advanced CAD

The design of scaffolds with an intricate and controlled internal structure represents a challenge for Tissue Engineering. Several scaffold manufacturing techniques allow the creation of complex and random architectures, but have little or no control over geometrical parameters such as pore size, shape and interconnectivity- things that are essential for tissue regeneration. The combined use of CAD software and layer manufacturing techniques allow a high degree of control over those parameters, resulting in reproducible geometrical architectures. However, the design of the complex and intricate network of channels that are required in conventional CAD, is extremely time consuming: manually setting thousands of different geometrical parameters may require several days in which to design the individual scaffold structures. This research proposes an automated design methodology in order to overcome those limitations. The combined use of Object Oriented Programming and advanced CAD software, allows the rapid generation of thousands of different geometrical elements. Each has a different set of parameters that can be changed by the software, either randomly or according to a given mathematical formula, so that they match the different distribution of geometrical elements such as pore size and pore interconnectivity. This work describes a methodology that has been used to design five cubic scaffolds with pore size ranging from about 200 to 800 µm, each with an increased complexity of the internal geometry.Mechanical Engineerin

How Are HOPE VI Families Faring? Health

While the primary goal of the HOPE VI program is to improve the living environment of public housing residents, it also aims to help residents move toward self-sufficiency by helping them find new or better jobs (see page 6). The program's Community Support Services (CSS) component can help identify what residents need, such as job training or placement, to make them more likely to find employment. Relocation itself might help residents find employment if they move to less poor neighborhoods with more job opportunities and better job information networks. Residents who move back to new mixed-income developments on the HOPE VI sites could experience similar improved job networks. However, whether these expectations of increased employment and self-sufficiency are realistic for HOPE VI residents is unclear. For both employed and nonemployed residents, the gap between household income and the income needed for housing and other costs of living is wide. The HOPE VI Panel Study is tracking the well-being of residents from five HOPE VI sites (see page 7). These respondents, mostly African American women, were extremely poor at baseline.[1] The vast majority reported household incomes below the poverty level, and over a third (35 percent) reported annual incomes of less than $5,000. Less than half (45 percent) of respondents were employed, and those who were working earned low wages (Popkin et al. 2002). This brief discusses income and employment findings for working-age adults under 62 years old two years after relocation started at the five HOPE VI Panel Study sites.[2] It examines various barriers to employment for respondents, and considers both expectations for future employment and the services and support systems that might best mitigate those barriers. Future research will examine how residents' employment experiences are affected as relocation is completed and some residents return to the revitalized developments. Brief #4 from the series "Metropolitan Housing and Communities: A Roof Over Their Heads".Notes from this section1. Because many health problems vary significantly by gender and race, and because over 90 percent of the adults in the HOPE VI Panel Study are women and 89 percent are African American, a sample of black women nationally is used as the comparison group. The national data cited in this brief are published by the U.S. Department of Health and Human Services, calculated from the National Health Interview Survey in 2001.National Health Interview Survey data are broken down by sex and race, but not further by poverty status. Nationally, approximately one-third of all black women live in households with incomes below the poverty level. Therefore, the comparison data are biased slightly upward in terms of better health because of the relatively better economic well-being of the national population of black women compared to the HOPE VI sample. Even limiting the comparisons to similar gender, race, and age groups, adults in the HOPE VI study experience health problems more often than other demographically similar groups

High-temperature, high-pressure optical cell

The invention is an optical cell for containment of chemicals under conditions of high temperature and high pressure. The cell is formed of a vitreous silica tube, two optical windows comprising a vitreous silica rod inserted into the ends of a tube, and fused into position in the tube ends. Windows are spaced apart to form a cavity enclosed by the tube and the windows. A hole is drilled radially through the tube and into the cavity. Another vitreous silica tube is fused to the silica tube around the hole to form the stem, which is perpendicular to the long axis of the tube. The open end of the stem is used to load chemicals into the cavity. Then the stem may be sealed, and if desired, it may be shortened in order to reduce the volume of the cavity, which extends into the stem

Factors Influencing Trade Area Capture in the Great Basin Area

International Relations/Trade,

Three-by-three bound entanglement with general unextendible product bases

We discuss the subject of Unextendible Product Bases with the orthogonality condition dropped and we prove that the lowest rank non-separable positive-partial-transpose states, i.e. states of rank 4 in 3 x 3 systems are always locally equivalent to a projection onto the orthogonal complement of a linear subspace spanned by an orthogonal Unextendible Product Basis. The product vectors in the kernels of the states belong to a non-zero measure subset of all general Unextendible Product Bases, nevertheless they can always be locally transformed to the orthogonal form. This fully confirms the surprising numerical results recently reported by Leinaas et al. Parts of the paper rely heavily on the use of Bezout's Theorem from algebraic geometry.Comment: 36 page

On the absence of Shapiro-like steps in certain mesoscopic S-N-S junctions

In DC transport through mesoscopic S-N-S junctions, it is known that the Josephson coupling decreases exponentially with increasing temperature, but the phase dependence of the conductance persists to much higher temperatures and decreases only as 1/T. It is pointed out here that, despite the fact that such a phase-dependent conductance does bring about an AC current for a pure DC voltage, it cannot, by itself, lead to the formation of Shapiro steps.Comment: 1 page, to be published in PRL (as Comment

Prediction of low frequency and impulsive sound radiation from horizontal axis wind turbines

Theoretical models to predict the radiation of low frequency and impulsive sound from horizontal axis wind turbines due to three sources: (1) steady blade loads; (2) unsteady blade loads due to operation in a ground shear; (3) unsteady loads felt by the blades as they cross the tower wake. These models are then used to predict the acoustic output of MOD-1, the large wind turbine operated near Boone, N.C. Predicted acoustic time signals are compared to those actually measured near MOD-1 and good agreement is obtained

Self-healing fuse

Fast-acting current limiting device provides current overload protection for vulnerable circuit elements and then re-establishes conduction path within milliseconds. Fuse can also perform as fast-acting switch to clear transient circuit overloads. Fuse takes advantage of large increase in electrical resistivity that occurs when liquid metal vaporizes