154 research outputs found
La Comisión Comahue del Instituto Argentino de Recursos HÃdricos
Preocupados por los problemas asociados al uso de agua y el ambiente, un grupo de Profesionales de las Provincias de RÃo Negro y Neuquén, se convocaron con la inquietud de conformar la Comisión Regional Comahue del Instituto Argentino de Recursos HÃdricos dada la importancia que presentan estos recursos en materia de uso, preservación, conflictos, acceso, degradación, administración y manejo para la región
Estimating Be Star Disk Radii using H-alpha Emission Equivalent Widths
We present numerical models of the circumstellar disks of Be stars, and we
describe the resulting synthetic H-alpha emission lines and maps of the
wavelength-integrated emission flux projected onto the sky. We demonstrate that
there are monotonic relationships between the emission line equivalent width
and the ratio of the angular half-width at half maximum of the projected disk
major axis to the radius of the star. These relationships depend mainly upon
the temperatures of the disk and star, the inclination of the disk normal to
the line of sight, and the adopted outer boundary for the disk radius. We show
that the predicted H-alpha disk radii are consistent with those observed
directly through long baseline interferometry of nearby Be stars (especially
once allowance is made for disk truncation in binaries and for dilution of the
observed H-alpha equivalent width by continuum disk flux in the V-band).Comment: 12 pages, 2 figures, ApJL in pres
Introduction to half-metallic Heusler alloys: Electronic Structure and Magnetic Properties
Intermetallic Heusler alloys are amongst the most attractive half-metallic
systems due to the high Curie temperatures and the structural similarity to the
binary semiconductors. In this review we present an overview of the basic
electronic and magnetic properties of both Heusler families: the so-called
half-Heusler alloys like NiMnSb and the the full-Heusler alloys like
CoMnGe. \textit{Ab-initio} results suggest that both the electronic and
magnetic properties in these compounds are intrinsically related to the
appearance of the minority-spin gap. The total spin magnetic moment
scales linearly with the number of the valence electrons , such that
for the full-Heusler and for the half-Heusler alloys,
thus opening the way to engineer new half-metallic alloys with the desired
magnetic properties.Comment: 28 pages, submitted for a special issue of 'Journal of Physics D:
Applied Physics' on Heusler alloy
Efficient analysis in planet transit surveys
With the growing number of projects dedicated to the search for extrasolar
planets via transits, there is a need to develop fast, automatic, robust
methods with a statistical background in order to efficiently do the analysis.
We propose a modified analysis of variance (AoV) test particularly suitable for
the detection of planetary transits in stellar light curves. We show how
savings of labor by a factor of over 10 could be achieved by the careful
organization of computations. Basing on solid analytical statistical
formulation, we discuss performance of our and other methods for different
signal-to-noise and number of observations.Comment: 7 pages, to be published in MNRAS, downloadable software from
http://www.camk.edu.pl/~alex/#softwar
Stringy Stability of Charged Dilaton Black Holes with Flat Event Horizon
Electrically charged black holes with flat event horizon in anti-de Sitter
space have received much attention due to various applications in Anti-de
Sitter/Conformal Field Theory (AdS/CFT) correspondence, from modeling the
behavior of quark-gluon plasma to superconductor. Crucial to the physics on the
dual field theory is the fact that when embedded in string theory, black holes
in the bulk may become vulnerable to instability caused by brane
pair-production. Since dilaton arises naturally in the context of string
theory, we study the effect of coupling dilaton to Maxwell field on the
stability of flat charged AdS black holes. In particular, we study the
stability of Gao-Zhang black holes, which are locally asymptotically anti-de
Sitter. We find that for dilaton coupling parameter > 1, flat black
holes are stable against brane pair production, however for 0 < < 1,
the black holes eventually become unstable as the amount of electrical charges
is increased. Such instability however, behaves somewhat differently from that
of flat Reissner-Nordstr\"om black holes. In addition, we prove that the
Seiberg-Witten action of charged dilaton AdS black hole of Gao-Zhang type with
flat event horizon (at least in 5-dimension) is always logarithmically
divergent at infinity for finite values of , and is finite and positive
in the case tends to infinity . We also comment on the robustness of
our result for other charged dilaton black holes that are not of Gao-Zhang
type.Comment: Fixed some confusions regarding whether part of the discussions
concern electrically charged hole or magnetically charged one. No changes to
the result
Role of defects and disorder in the half-metallic full-Heusler compounds
Half-metallic ferromagnets and especially the full-Heusler alloys containing
Co are at the center of scientific research due to their potential applications
in spintronics. For realistic devices it is important to control accurately the
creation of defects in these alloys. We review some of our late results on the
role of defects and impurities in these compounds. More precisely we present
results for the following cases (i) doping and disorder in CoCr(Mn)Al(Si)
alloys, (ii) half-metallic ferrimagnetism appeared due to the creation of
Cr(Mn) antisites in these alloys, (iii) Co-doping in MnVAl(Si) alloys
leading to half-metallic antiferromagnetism, and finally (iv) the occurrence of
vacancies in the full-Heusler alloys containing Co and Mn. These results are
susceptible of encouraging further theoretical and experimental research in the
properties of these compounds.Comment: Chapter intended for a book with contributions of the invited
speakers of the International Conference on Nanoscale Magnetism 2007. Revised
version contains new figure
SimHap GUI: An intuitive graphical user interface for genetic association analysis
<p>Abstract</p> <p>Background</p> <p>Researchers wishing to conduct genetic association analysis involving single nucleotide polymorphisms (SNPs) or haplotypes are often confronted with the lack of user-friendly graphical analysis tools, requiring sophisticated statistical and informatics expertise to perform relatively straightforward tasks. Tools, such as the <it>SimHap </it>package for the R statistics language, provide the necessary statistical operations to conduct sophisticated genetic analysis, but lacks a graphical user interface that allows anyone but a professional statistician to effectively utilise the tool.</p> <p>Results</p> <p>We have developed SimHap GUI, a cross-platform integrated graphical analysis tool for conducting epidemiological, single SNP and haplotype-based association analysis. SimHap GUI features a novel workflow interface that guides the user through each logical step of the analysis process, making it accessible to both novice and advanced users. This tool provides a seamless interface to the <it>SimHap </it>R package, while providing enhanced functionality such as sophisticated data checking, automated data conversion, and real-time estimations of haplotype simulation progress.</p> <p>Conclusion</p> <p>SimHap GUI provides a novel, easy-to-use, cross-platform solution for conducting a range of genetic and non-genetic association analyses. This provides a free alternative to commercial statistics packages that is specifically designed for genetic association analysis.</p
How to screen for non-adherence to antihypertensive therapy
The quality of assessment of non-adherence to treatment in hypertensive is poor. Within this review, we discuss the different methods used to assess adherence to blood-pressure-lowering medications in hypertension patients. Subjective reports such as physicians’ perceptions are inaccurate, and questionnaires completed by patients tend to overreport adherence and show a low diagnostic specificity. Indirect objective methods such as pharmacy database records can be useful, but they are limited by the robustness of the recorded data. Electronic medication monitoring devices are accurate but usually track adherence to only a single medication and can be expensive. Overall, the fundamental issue with indirect objective measures is that they do not fully confirm ingestion of antihypertensive medications. Detection of antihypertensive medications in body fluids using liquid chromatography–tandem mass spectrometry is currently, in our view, the most robust and clinically useful method to assess non-adherence to blood-pressure-lowering treatment. It is particularly helpful in patients presenting with resistant, refractory or uncontrolled hypertension despite the optimal therapy. We recommend using this diagnostic strategy to detect non-adherence alongside a no-blame approach tailoring support to address the perceptions (e.g. beliefs about the illness and treatment) and practicalities (e.g. capability and resources) influencing motivation and ability to adhere
‘Sub-Prime’ Water, Low-Security Entitlements and Policy Challenges in Over-Allocated River Basins: the Case of the Murray–Darling Basin
Environmental policy is often implemented using market instruments. In some cases, including carbon taxing, the links
between financial products and the environmental objectives, are transparent. In other cases, including water markets, the
links are less transparent. In Australia’s Murray–Darling Basin (MDB), financial water products are known as ‘entitlements’,
and are similar to traditional financial products, such as shares. The Australian water market includes ‘Low Security’
entitlements, which are similar to ‘sub-prime’ mortgage bonds because they are unlikely to yield an amount equal to their
financial worth. Nearly half the water purchased under the Murray–Darling Basin Plan for environmental purposes is ‘Low
Security’. We suggest that the current portfolio of water held by the Australian Government for environmental purposes
reflects the mortgage market in the lead-up to the global financial crisis. Banks assumed that the future value of the mortgage
market would reflect past trends. Similarly, it is assumed that the future value of water products will reflect past trends,
without considering climate change. Historic records of allocations to ‘Low Security’ entitlements in the MDB suggest that,
in the context of climate change, the Basin Plan water portfolio may fall short of the target annual average yield of 2075 GL
by 511 GL. We recommend adopting finance sector methods including ‘hedging’ ‘Low Security’ entitlements by purchasing
an additional 322–2755 GL of ‘Low Security’, or 160–511 GL of ‘High Security’ entitlements. Securing reliable
environmental water is a global problem. Finance economics present opportunities for increasing the reliability of
environmental flows
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