Pion susceptibility of the QCD vacuum from an effective quark-quark interaction

A modified method for calculating the pion vacuum susceptibility from an effective quark-quark interaction model is derived. Within this approach it is shown that the pion vacuum susceptibility is free of ultraviolet divergence and is much smaller than the previous estimations.Comment: 13 pages, 2 figure

Provably scale-covariant networks from oriented quasi quadrature measures in cascade

This article presents a continuous model for hierarchical networks based on a combination of mathematically derived models of receptive fields and biologically inspired computations. Based on a functional model of complex cells in terms of an oriented quasi quadrature combination of first- and second-order directional Gaussian derivatives, we couple such primitive computations in cascade over combinatorial expansions over image orientations. Scale-space properties of the computational primitives are analysed and it is shown that the resulting representation allows for provable scale and rotation covariance. A prototype application to texture analysis is developed and it is demonstrated that a simplified mean-reduced representation of the resulting QuasiQuadNet leads to promising experimental results on three texture datasets.Comment: 12 pages, 3 figures, 1 tabl

Exploring the Universe with Metal-Poor Stars

The early chemical evolution of the Galaxy and the Universe is vital to our understanding of a host of astrophysical phenomena. Since the most metal-poor Galactic stars (with metallicities down to [Fe/H]\sim-5.5) are relics from the high-redshift Universe, they probe the chemical and dynamical conditions of the Milky Way and the origin and evolution of the elements through nucleosynthesis. They also provide constraints on the nature of the first stars, their associated supernovae and initial mass function, and early star and galaxy formation. The Milky Way's dwarf satellites contain a large fraction (~30%) of the known most metal-poor stars that have chemical abundances that closely resemble those of equivalent halo stars. This suggests that chemical evolution may be universal, at least at early times, and that it is driven by massive, energetic SNe. Some of these surviving, ultra-faint systems may show the signature of just one such PopIII star; they may even be surviving first galaxies. Early analogs of the surviving dwarfs may thus have played an important role in the assembly of the old Galactic halo whose formation can now be studied with stellar chemistry. Following the cosmic evolution of small halos in simulations of structure formation enables tracing the cosmological origin of the most metal-poor stars in the halo and dwarf galaxies. Together with future observations and additional modeling, many of these issues, including the reionization history of the Milky Way, may be constrained this way. The chapter concludes with an outlook about upcoming observational challenges and ways forward is to use metal-poor stars to constrain theoretical studies.Comment: 34 pages, 11 figures. Book chapter to appear in "The First Galaxies - Theoretical Predictions and Observational Clues", 2012 by Springer, eds. V. Bromm, B. Mobasher, T. Wiklin

Management of Community Acquired Pneumonia (CAP) in Children: Clinical Practice Guidelines by the Paediatrics Association of Nigeria (PAN)

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Effective localized collection and identification of airborne species through electrodynamic precipitation and SERS-based detection

Various nanostructured sensor designs currently aim to achieve or claim single molecular detection by a reduction of the active sensor size. However, a reduction of the sensor size has the negative effect of reducing the capture probability considering the diffusion-based analyte transport commonly used. Here we introduce and apply a localized programmable electrodynamic precipitation concept as an alternative to diffusion. The process provides higher collection rates of airborne species and detection at lower concentration. As an example, we compare an identical nanostructured surfaced-enhanced Raman spectroscopy sensor with and without localized delivery and find that the sensitivity and detection time is improved by at least two orders of magnitudes. Localized collection in an active-matrix array-like fashion is also tested, yielding hybrid molecular arrays on a single chip over a broad range of molecular weights, including small benzenethiol (110.18 Da) and 4-fluorobenzenethiol (128.17 Da), or large macromolecules such as anti-mouse IgG (~150 kDa)

Evidence for the role of EPHX2 gene variants in anorexia nervosa.

Anorexia nervosa (AN) and related eating disorders are complex, multifactorial neuropsychiatric conditions with likely rare and common genetic and environmental determinants. To identify genetic variants associated with AN, we pursued a series of sequencing and genotyping studies focusing on the coding regions and upstream sequence of 152 candidate genes in a total of 1205 AN cases and 1948 controls. We identified individual variant associations in the Estrogen Receptor-ß (ESR2) gene, as well as a set of rare and common variants in the Epoxide Hydrolase 2 (EPHX2) gene, in an initial sequencing study of 261 early-onset severe AN cases and 73 controls (P=0.0004). The association of EPHX2 variants was further delineated in: (1) a pooling-based replication study involving an additional 500 AN patients and 500 controls (replication set P=0.00000016); (2) single-locus studies in a cohort of 386 previously genotyped broadly defined AN cases and 295 female population controls from the Bogalusa Heart Study (BHS) and a cohort of 58 individuals with self-reported eating disturbances and 851 controls (combined smallest single locus P<0.01). As EPHX2 is known to influence cholesterol metabolism, and AN is often associated with elevated cholesterol levels, we also investigated the association of EPHX2 variants and longitudinal body mass index (BMI) and cholesterol in BHS female and male subjects (N=229) and found evidence for a modifying effect of a subset of variants on the relationship between cholesterol and BMI (P<0.01). These findings suggest a novel association of gene variants within EPHX2 to susceptibility to AN and provide a foundation for future study of this important yet poorly understood condition

Survey of the knowledge, attitude and practice of Nigerian surgery trainees to HIV-infected persons and AIDS patients

BACKGROUND: The incidence of HIV infection and AIDS is rising in Nigeria. Surgeons are at risk of occupationally acquired infection as a result of intimate contact with the blood and body fluids of patients. This study set out to determine the knowledge, attitude and risk perception of Nigerian surgery residents to HIV infection and AIDS. METHODS: A self-administered postal questionnaire was sent to all surgery trainees in Nigeria in 1997. RESULTS: Parenteral exposure to patients' blood was reported as occurring 92.5% times, and most respondents assessed their risk of becoming infected with HIV as being moderate at 1–5%. The majority of the respondents were not aware of the CDC guidelines on universal precautions against blood-borne pathogens. Most support a policy of routinely testing all surgical patients for HIV infection but 76.8% work in centers where there is no policy on parenteral exposure to patients' blood and body fluids. Most (85.6%) do not routinely use all the protective measures advocated for the reduction of transmission of blood borne pathogens during surgery, with the majority ascribing this to non-availability. Most want surgeons to be the primary formulators of policy on HIV and surgery while not completely excluding other stakeholders. CONCLUSIONS: The study demonstrates the level of knowledge, attitude and practice of Nigerian surgery trainees in 1997 and the need for policy guidelines to manage all aspects of the healthcare worker (HCW), patients, and HIV/AIDS interaction

Measuring Intergroup Forgiveness: The Enright Group Forgiveness Inventory

Until recently, researchers operationalized and measured the psychological construct of forgiveness at the individual, rather than the group, level. Social psychologists started applying forgiveness to groups and examining the role intergroup forgiveness may have in conflict resolution and peace efforts. Initial attempts to define and measure forgiveness at the group level either assumed individual and group capacities were the same, or insufficiently described what intergroup forgiveness meant. We developed a new measure of intergroup forgiveness, and a novel group administration process, that operationalized the construct in a philosophically coherent way. Our conceptualization of intergroup forgiveness was rooted in what groups, as opposed to the individuals who compose them, have the capacity to do. We collected data on the psychometric properties of the measure with 595 participants in three different geographic and cultural settings. We assessed the factor structure, internal consistency, and validity of the measure. We also assessed a novel group-based method of administering the measure to better understand the relationship between group based reports and self-reports of intergroup forgiveness. The factor structure of the measure was supported, and the measure had strong internal consistency, as well as convergent and discriminant validity. The group administration process revealed important group dynamics and was not statistically different than a standard self-report administration; this finding has important implications for research and practice