Searches for Metal-Poor Stars from the Hamburg/ESO Survey using the CH G-band

We describe a new method to search for metal-poor candidates from the Hamburg/ESO objective-prism survey (HES) based on identifying stars with apparently strong CH G-band strengths for their colors. The hypothesis we exploit is that large over-abundances of carbon are common among metal-poor stars. The selection was made by considering two line indices in the 4300A region, applied directly to the low-resolution prism spectra. This work also extends a previously published method by adding bright sources to the sample. The spectra of these stars suffer from saturation effects, compromising the index calculations and leading to an undersampling of the brighter candidates. Visual inspection and classification of the spectra from the HES plates yielded a list of 5,288 new metal-poor candidates, which are presently being used as targets for medium-resolution spectroscopic follow-up. Estimates of the stellar atmospheric parameters, as well as carbon abundances, are now available for 117 of the first candidates, based on follow-up medium-resolution spectra obtained with the SOAR 4.1m and Gemini 8m telescopes. We demonstrate that our new method improves the metal-poor star fractions found by our pilot study by up to a factor of three in the same magnitude range, as compared with our pilot study based on only one CH G-band index. Our selection scheme obtained roughly a 40% success rate for identification of stars with [Fe/H] < -1.0; the primary contaminant is late-type stars with near solar abundances and, often, emission line cores that filled in the CaII K line on the prism spectrum. Because the selection is based on carbon, we greatly increase the numbers of known CEMP stars from the HES with intermediate metallicities -2.0 < [Fe/H] < -1.0, which previous survey efforts undersampled. There are eight newly discovered stars with [Fe/H] < -3.0 in our sample, including two with [Fe/H] < -3.5.Comment: 18 pages, 13 figures; accepted for publication in A

Automatic covariate selection in logistic models for chest pain diagnosis: A new approach

A newly established method for optimizing logistic models via a minorization-majorization procedure is applied to the problem of diagnosing acute coronary syndromes (ACS). The method provides a principled approach to the selection of covariates which would otherwise require the use of a suboptimal method owing to the size of the covariate set. A strategy for building models is proposed and two models optimized for performance and for simplicity are derived via ten-fold cross-validation. These models confirm that a relatively small set of covariates including clinical and electrocardiographic features can be used successfully in this task. The performance of the models is comparable with previously published models using less principled selection methods. The models prove to be portable when tested on data gathered from three other sites. Whilst diagnostic accuracy and calibration diminishes slightly for these new settings, it remains satisfactory overall. The prospect of building predictive models that are as simple as possible for a required level of performance is valuable if data-driven decision aids are to gain wide acceptance in the clinical situation owing to the need to minimize the time taken to gather and enter data at the bedside

Optical properties of pyrochlore oxide Pb2Ru2O7−δPb_{2}Ru_{2}O_{7-{\delta}}

We present optical conductivity spectra for $Pb_{2}Ru_{2}O_{7-{\delta}}$ single crystal at different temperatures. Among reported pyrochlore ruthenates, this compound exhibits metallic behavior in a wide temperature range and has the least resistivity. At low frequencies, the optical spectra show typical Drude responses, but with a knee feature around 1000 \cm. Above 20000 \cm, a broad absorption feature is observed. Our analysis suggests that the low frequency responses can be understood from two Drude components arising from the partially filled Ru $t_{2g}$ bands with different plasma frequencies and scattering rates. The high frequency broad absorption may be contributed by two interband transitions: from occupied Ru $t_{2g}$ states to empty $e_{g}$ bands and from the fully filled O 2p bands to unoccupied Ru $t_{2g}$ states.Comment: 4 pages, 6 figure

Optical investigations on Y2−xBixRu2O7Y_{2-x} Bi_x Ru_2 O_7: Electronic structure evolutions related to the metal-insulator transition

Optical conductivity spectra of cubic pyrochlore $Y_{2-x} Bi_x Ru_2 O_7$ (0.0$\leq${\it x}$\leq$2.0) compounds are investigated. As a metal-insulator transition (MIT) occurs around {\it x}$=$0.8, large spectral changes are observed. With increase of {\it x}, the correlation-induced peak between the lower and the upper Hubbard bands seems to be suppressed, and a strong mid-infrared feature is observed. In addition, the $p-d$ charge transfer peak shifts to the lower energies. The spectral changes cannot be explained by electronic structural evolutions in the simple bandwidth-controlled MIT picture, but are consistent with those in the filling-controlled MIT picture. In addition, they are also similar to the spectral changes of Y$_{2-x}$Ca$_{x}$Ru$_{2}$O$_{7}$ compounds, which is a typical filling-controlled system. This work suggests that, near the MIT, the Ru bands could be doped with the easily polarizable Bi cations.Comment: 5 figure

The relation between the diagonal entries and the eigenvalues of a symmetric matrix, based upon the sign pattern of its off-diagonal entries

It is known that majorization is a complete description of the relationships between the eigenvalues and diagonal entries of real symmetric matrices. However, for large subclasses of such matrices, the diagonal entries impose much greater restrictions on the eigenvalues. Motivated by previous results about Laplacian eigenvalues, we study here the additional restrictions that come from the off-diagonal sign-pattern classes of real symmetric matrices. Each class imposes additional restrictions. Several results are given for the all nonpositive and all nonnegative classes and for the third class that appears when n = 4. Complete description of the possible relationships are given in low dimensions. (C) 2012 Elsevier Inc. All rights reserved

Guidelines on assessing biodiverse foods in dietary intake surveys

FAO produced these guidelines in collaboration with Bioversity International with the aim of facilitating the work of researchers who wish to capture biodiversity aspects (appropriate levels of taxonomic identification of foods) incommonly used dietary surveys, including 24-hour recall, food records, food frequency questionnaires (FFQ) and dietary diversity surveys. For the sake of simplicity, these guidelines focus on plant foods, which is where the expertise of Bioversity International lies, but similar principles could be applied to animal foods, insects, fish and other aquatic species, with the support of appropriate experts. The guidelines are intended as a practical tool, and describe the preparatory steps involved in assessing and documenting local foods, with appropriate levels of detail in taxonomic identification.This is followed by suggestions on how to adapt dietary assessment instruments to collect information on biodiverse foods

Nonpositive Eigenvalues of the Adjacency Matrix and Lower Bounds for Laplacian Eigenvalues

Let $NPO(k)$ be the smallest number $n$ such that the adjacency matrix of any undirected graph with $n$ vertices or more has at least $k$ nonpositive eigenvalues. We show that $NPO(k)$ is well-defined and prove that the values of $NPO(k)$ for $k=1,2,3,4,5$ are $1,3,6,10,16$ respectively. In addition, we prove that for all $k \geq 5$, $R(k,k+1) \ge NPO(k) > T_k$, in which $R(k,k+1)$ is the Ramsey number for $k$ and $k+1$, and $T_k$ is the $k^{th}$ triangular number. This implies new lower bounds for eigenvalues of Laplacian matrices: the $k$-th largest eigenvalue is bounded from below by the $NPO(k)$-th largest degree, which generalizes some prior results.Comment: 23 pages, 12 figure

The Multilayer Perceptron as an Aid to the Early Diagnosis of Myocardial Infarction

The establishment of a decision aid for the early diagnosis of myocardial infarction is described.The system uses a multi-layer Perceptron structure and is trained in the usual way. It is shown that the performance of the network can exceed that of the admitting clinicians, a panel of senior physicians in a large teaching hospital and a protocol derived using conventional statistical methods over a wide range of performance measures. In particular, the network demonstrates the highly specific behaviour necessary when making the decision whether or not to administer thrombolytic therapy-a potentially life-saving decision which must be taken in the very early stages, long before confirmatory laboratory test results are available. The network is compact and has been implemented on a portable computer. In operation it responds very quickly, giving its diagnosis and recommendations (taking account of clinical opinion) in a fraction of the time taken to input the patient's symptoms

Implementing and managing self-management skills training within primary care organisations: a national survey of the expert patients programme within its pilot phase

A key element of the United Kingdom (UK) health policy reform in relation to chronic disease management is the introduction of a national programme seeking to promote self-care from within the National Health Service (NHS). The mainstay of the Expert Patients Programme (EPP) is a six-week training course that provides the opportunity for anyone with a long-term condition to develop new skills to manage their condition better on a day-to-day basis. The course forms part of the NHS self-care support programme, is administered by Primary Care Trusts (PCTs) and delivered by people who have personal experience of living with a long-term condition. The NHS' official Expert Patients Programme website presently states that, "Pilot EPP courses began at 26 NHS PCT sites across England in May 2002, and by May 2004 approximately 300 PCTs had either actively implemented pilot courses or had committed to joining. The majority of PCTs are now coming to the end of the pilot phase, with many implementing plans to make EPP sustainable for the long-term." The NHS website heralds the pilot "a success." A national, postal survey of PCT EPP Leads was undertaken in order to examine both the evolvement of EPP during its pilot stage and future plans for the programme. A questionnaire was sent out to the 299 PCTs known to have committed to the EPP pilot, and an excellent 100% response rate was obtained over a 3-month period (April-July 2005). One marker of success of the Expert Patients Programme implementation is the actual running of courses by the Primary Care Trusts. This paper explores the extent to which the implementation of the pilot can indeed be viewed as a "success," primarily in terms of the number of courses run, and considers the extent to which PCTs have carried out all that they were committed to do. Findings suggest that the more time an EPP Lead dedicates to the Programme, the more likely it is that EPP has run successfully in the past, and the more likely it is that it will continue to run successfully in the future. Other factors indicating future EPP success include collaborating across PCTs to share co-ordinators, tutors, and funding

Solution structure of a repeated unit of the ABA-1 nematode polyprotein allergen of ascaris reveals a novel fold and two discrete lipid-binding sites

Parasitic nematode worms cause serious health problems in humans and other animals. They can induce allergic-type immune responses, which can be harmful but may at the same time protect against the infections. Allergens are proteins that trigger allergic reactions and these parasites produce a type that is confined to nematodes, the nematode polyprotein allergens (NPAs). These are synthesized as large precursor proteins comprising repeating units of similar amino acid sequence that are subsequently cleaved into multiple copies of the allergen protein. NPAs bind small lipids such as fatty acids and retinol (Vitamin A) and probably transport these sensitive and insoluble compounds between the tissues of the worms. Nematodes cannot synthesize these lipids, so NPAs may also be crucial for extracting nutrients from their hosts. They may also be involved in altering immune responses by controlling the lipids by which the immune and inflammatory cells communicate. We describe the molecular structure of one unit of an NPA, the well-known ABA-1 allergen of Ascaris and find its structure to be of a type not previously found for lipid-binding proteins, and we describe the unusual sites where lipids bind within this structur