Hypervelocity impact facility for simulating materials exposure to impact by space debris

As a result of man's venturing into space, the local debris contributed by his presence exceeds, at some orbital altitudes, that of the natural component. Man's contribution ranges from fuel residue to large derelect satellites that weigh many kilograms. Current debris models are able to predict the growth of the problem and suggest that spacecraft must employ armor or bumper shields for some orbital altitudes now, and that, the problem will become worse as a function of time. The practical upper limit to the velocity distribution is on the order of 40 km/s and is associated with the natural environment. The maximum velocity of the man-made component is in the 14-16 km/s range. The Long Duration Exposure Facility (LDEF) has verified that the 'high probability of impact' particles are in the microgram to milligram range. These particles can have significant effects on coatings, insulators, and thin metallic layers. The surface of thick materials becomes pitted and the local debris component is enhanced by ejecta from the debris spectrum in a controlled environment. The facility capability is discussed in terms of drive geometry, energetics, velocity distribution, diagnostics, and projectile/debris loading. The facility is currently being used to study impact phenomena on Space Station Freedom's solar array structure, other solar array materials, potential structural materials for use in the station, electrical breakdown in the space environment, and as a means of clarifying or duplicating the impact phenomena on the LDEF surfaces. The results of these experiments are described in terms of the mass/velocity distribution incident on selected samples, crater dynamics, and sample geometry

Short-term PsychoEducation for Carers To Reduce Over Medication of people with intellectual disabilities (SPECTROM): study protocol

Introduction Psychotropic medications that are primarily licenced for the treatment of psychiatric disorders are used widely (32%–85%) among people with intellectual disabilities (ID) often for the management of problem (challenging) behaviour in the absence of a psychiatric disorder. Care staff play a pivotal role in the prescribing process. Currently, no staff training programme exists to address the issue of overprescribing of psychotropic medication in people with ID, thus highlighting an urgent need for developing a psychoeducational programme (PEP) specifically designed to address this issue. We propose to develop a PEP for care staff using the methodology described in the UK Medical Research Council guide for complex interventions. Methods and analysis The development of the PEP will involve (1) gathering information on available relevant training programmes, (2) running four focus groups with care staff and other professionals to establish the content and format of the PEP, and (3) organising a co-design event involving all relevant stakeholders to discuss the format of the PEP. A core project team will develop the PEP under guidance from the PEP Development Group which will consist of 10–12 relevant stakeholder representatives. Feedback from selected stakeholders on a draft PEP will allow us to refine the PEP before implementation. The PEP will have web-based modules supplemented by face to face training sessions. When the final draft is ready, we will field test the PEP on six to eight care staff from community care homes for people with ID. After completing the field test, we will run a focus group involving participants in the PEP to get feedback on the PEP. Ethics and dissemination Ethics approval for this study was waived by the UK Health Regulatory Authority as the study does not collect any patient related information and only include care staff outside the UK NHS. This will be the first ever such universally freely available PEP supported by training manual and slides

Differing microstructural properties of 7075-T6 sheet and 7075-T651 extruded aluminium alloy

This paper details an initial study of the differences, if any, in corrosion behaviour between 7075-T6 sheet and 7075-T651 extruded aluminium alloy. The study involved a visual inspection of the grain structure of each material and an analysis of the grain sizes. It was found that there is a significant difference in the grain sizes of the two materials; the extruded material had grains that were approximately 15-20% of the size of the sheet grains. Also, the grains in the sheet material were wider, with a length-to-width aspect ratio of 1.5 (compared with 1.3 for the extruded material). Finally, the grains in the extruded material appeared to form a semi-continuous line of grain boundaries, possibly facilitating the growth of laminar intergranular corrosion; the sheet material contained higher-angle grain boundary junctions which should limit the amount of laminar intergranular corrosion produced and promote networked intergranular corrosion. Further testing will involve corroding specimens and investigating the size, shape and depth of the corrosion produced

Multi-gene panel testing for hereditary cancer predisposition in unsolved high-risk breast and ovarian cancer patients.

PurposeMany women with an elevated risk of hereditary breast and ovarian cancer have previously tested negative for pathogenic mutations in BRCA1 and BRCA2. Among them, a subset has hereditary susceptibility to cancer and requires further testing. We sought to identify specific groups who remain at high risk and evaluate whether they should be offered multi-gene panel testing.MethodsWe tested 300 women on a multi-gene panel who were previously enrolled in a long-term study at UCSF. As part of their long-term care, all previously tested negative for mutations in BRCA1 and BRCA2 either by limited or comprehensive sequencing. Additionally, they met one of the following criteria: (i) personal history of bilateral breast cancer, (ii) personal history of breast cancer and a first or second degree relative with ovarian cancer, and (iii) personal history of ovarian, fallopian tube, or peritoneal carcinoma.ResultsAcross the three groups, 26 women (9%) had a total of 28 pathogenic mutations associated with hereditary cancer susceptibility, and 23 women (8%) had mutations in genes other than BRCA1 and BRCA2. Ashkenazi Jewish and Hispanic women had elevated pathogenic mutation rates. In addition, two women harbored pathogenic mutations in more than one hereditary predisposition gene.ConclusionsAmong women at high risk of breast and ovarian cancer who have previously tested negative for pathogenic BRCA1 and BRCA2 mutations, we identified three groups of women who should be considered for subsequent multi-gene panel testing. The identification of women with multiple pathogenic mutations has important implications for family testing

Photochemistry of ozone over the western Pacific from winter to spring

Aircraft measurements of ozone (O3) and its precursors, including NO, CO, H2O, and nonmethane hydrocarbons (NMHCs), were made over the western Pacific in the 20° - 45°N latitude range in January and April-May 2002 during the Pacific Exploration of Asian Continental Emission (PEACE)-A and B campaigns. These measurements have provided data sets that, in combination with Transport and Chemical Evolution over the Pacific (TRACE-P) data taken in March 2001, enable studies of O3 photochemistry from winter to late spring. A photochemical box model is used to calculate ozone formation (F(O3)) and destruction (D(O3)) rates constrained by the observed species concentrations. The values of F(O3) and D(O3) are controlled directly by NO, J(O1D) (O3 photolysis frequency), H2O, OH, and HO2. Changes in HO2 concentration cause corresponding changes in both F(O3) and D(O3) leading to their coupling. Concentrations of these species, which are strongly influenced by photochemistry and transport from the Asian continent, underwent large seasonal variations. In the boundary layer (0-3 km), NO was much higher in January than in April-May, because of stronger winds, lower convective activities, and lower oxidation rates by OH in winter. The net O3 formation rate, given by P(O3) = F(O3) - D(O3), was largely positive in the boundary layer at 30°-45°N (1.5-4 ppbv d-1) in January, mainly because of high NO and low H2O values. Net O3 formation continued from January to the end of March, demonstrating that the western Pacific is an important O3 source region during this season. Net O3 formation nearly ceased by late April/May because of the decrease in NO and the increase in H2O. In the latitude range of 20°-30°N, P(O3) in the boundary layer was positive in January and turned negative by March. The earlier transition was mainly due to lower NO and higher H2O concentrations, combined with weaker transport and higher temperatures than those at 30°-45°N. The upper troposphere (6-12 km) has been shown to be a region of net O3 formation throughout most of the year because of high NO and low H2O. The present study illustrates that a decrease in the net O3 formation rate at 20°-45°N latitude from winter to late spring is explained systematically by the increases in J(O1D), H2O, OH, and HO2 (primarily due to increases in temperature and solar radiation) and the decrease in NO (primarily due to decrease in transport from the Asian continent). Differences in the seasonal variation of O3 photochemistry observed over the North American continent are interpreted in terms of the differences in factors controlling O3 formation and destruction. Copyright 2004 by the American Geophysical Union

Dzyaloshinsky-Moriya Spin Canting in the LTT Phase of La2-x-yEuySrxCuO4

The Cu spin magnetism in La2-x-yEuySrxCuO4 (x<=0.17; y<=0.2) has been studied by means of magnetization measurements up to 14 T. Our results clearly show that in the antiferromagnetic phase Dzyaloshinsky-Moriya (DM)superexchange causes Cu spin canting not only in the LTO phase but also in the LTLO and LTT phases. In La1.8Eu0.2CuO4 the canted DM-moment is about 50% larger than in pure La2CuO4 which we attribute to the larger octahedral tilt angle. We also find clear evidence that the size of the DM-moment does not change significantly at the structural transition at T_LT from LTO to LTLO and LTT. The most important change induced by the transition is a significant reduction of the magnetic coupling between the CuO2 planes. As a consequence, the spin-flip transition of the canted Cu spins which is observed in the LTO phase for magnetic field perpendicular to the CuO2 planes disappears in the LTT phase. The shape of the magnetization curves changes from the well known spin-flip type to a weak-ferromagnet type. However, no spontaneous weak ferromagnetism is observed even at very low temperatures, which seems to indicate that the interlayer decoupling in our samples is not perfect. Nonetheless, a small fraction (<15%) of the DM-moments can be remanently magnetized throughout the entire antiferromagnetically ordered LTT/LTLO phase, i.e. for T<T_LT and x<0.02. It appears that the remanent DM-moment is perpendicular to the CuO2 planes. For magnetic field parallel to the CuO2 planes we find that the critical field of the spin-flop transition decreases in the LTLO phase, which might indicate a competition between different in-plane anisotropies. To study the Cu spin magnetism in La2-x-yEuySrxCuO4, a careful analysis of the Van Vleck paramagnetism of the Eu3+ ions was performed.Comment: 22 pages, 27 figure

Population sub-structure and patterns of quantitative variation among the Gollas of Southern Andhra Pradesh, India

This is the published version, also available here: http://digitalcommons.wayne.edu/humbiol/vol73/iss2/9/.Population substructure and biological differentiation was studied among the Golla, a pastoral caste living in the southern areas of Andhra Pradesh (AP) in India, using 11 anthropometric measurements and 20 quantitative dermatoglyphic variables. The data were collected from a sample of 334 adult males drawn from 30 villages distributed in the Chittoor district of AP, who belonged to 8 endogamous subunits of the same caste. Multiple discriminant analysis of the anthropometrics suggests a highly significant degree of discrimination that is consistent with the microgeographic variations of the groups. In contrast, in different sets of dermatoglyphs discrimination is low and generally inconsistent with both the geographic and ethnohistorical affiliations of the groups. These findings are reflected in the FST value for anthropometry, which is more than double the value of dermatoglyphs. The patterns of gene flow as inferred through the regression of phenotypic variance on the distance of groups from the centroid is not generally consistent with the known backgrounds in the case of either dermatoglyphs or anthropometry. It is concluded that at the level of caste substructure representing the lowest level of population hierarchy, the quantitative variables examined here may not portray a complete picture of the historical process of subdivision. The results of this study are not in congruence with those based on another study of 13 short tandem repeat loci on the same set of populations (Reddy et al. 2001), which may provide better insights into the population structure and history of subdivision that are consistent with the known ethnohistorical backgrounds of the populations

Low frequency noise characteristics of sub-micron magnetic tunnel junctions

We report that low frequency (up to 200 kHz) noise spectra of magnetic tunnel junctions with areas ~10^{-10}cm^2$ at 10 Kelvin deviate significantly from the typical 1/f behavior found in large area junctions at room temperature. In most cases, a Lorentzian-like shape with characteristic time between 0.1 and 10 ms is observed, which indicates only a small number of fluctuators contribute to the measured noise. By investigating the dependence of noise on both the magnitude and orientation of an applied magnetic field, we find that magnetization fluctuations in both free and reference layers are the main sources of noise in these devices. At small fields, where the noise from the free layer is dominant, a linear relation between the measured noise and angular magnetoresistance susceptibility can be established.Comment: 3 pages, 2 figure

Trajectories in phase diagrams, growth processes and computational complexity: how search algorithms solve the 3-Satisfiability problem

Most decision and optimization problems encountered in practice fall into one of two categories with respect to any particular solving method or algorithm: either the problem is solved quickly (easy) or else demands an impractically long computational effort (hard). Recent investigations on model classes of problems have shown that some global parameters, such as the ratio between the constraints to be satisfied and the adjustable variables, are good predictors of problem hardness and, moreover, have an effect analogous to thermodynamical parameters, e.g. temperature, in predicting phases in condensed matter physics [Monasson et al., Nature 400 (1999) 133-137]. Here we show that changes in the values of such parameters can be tracked during a run of the algorithm defining a trajectory through the parameter space. Focusing on 3-Satisfiability, a recognized representative of hard problems, we analyze trajectories generated by search algorithms using growth processes statistical physics. These trajectories can cross well defined phases, corresponding to domains of easy or hard instances, and allow to successfully predict the times of resolution.Comment: Revtex file + 4 eps figure