1,711 research outputs found

    Foreword

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    Meeting the challenges of micronutrient deficiencies in emergency-affected populations

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    Micronutrient deficiencies occur frequently in refugee and displaced populations. These deficiency diseases include, in addition to the most common Fe and vitamin A deficiencies, scurvy (vitamin C deficiency), pellagra (niacin and/or tryptophan deficiency) and beriberi (thiamin deficiency), which are not seen frequently in non-emergency-affected populations. The main causes of the outbreaks have been inadequate food rations given to populations dependent on food aid. There is no universal solution to the problem of micronutrient deficiencies, and not all interventions to prevent the deficiency diseases are feasible in every emergency setting. The preferred way of preventing these micronutrient deficiencies would be by securing dietary diversification through the provision of vegetables, fruit and pulses, which may not be a feasible strategy, especially in the initial phase of a relief operation. The one basic emergency strategy has been to include a fortified blended cereal in the ration of all food-aid-dependent populations (United Nations High Commissioner for Refugees/World Food Programme, 1997). In situations where the emergency-affected population has access to markets, recommendations have been to increase the general ration to encourage the sale and/or barter of a portion of the ration in exchange for locally-available fruit and vegetables (World Health Organization, 1999a, b, 2000). Promotion of home gardens as well as promotion of local trading are recommended longer-term options aiming at the self-sufficiency of emergency-affected households. The provision of fortified blended foods in the general ration has successfully prevented and controlled micronutrient deficiencies in various emergency settings. However, the strategy of relying only on fortified blended foods to prevent micronutrient deficiencies should be reviewed in the light of recurring evidence that provision of adequate supplies of these foods is often problematic. Donor policies on the bartering or exchange of food aid should also be clarified. Furthermore, the establishment of micronutrient surveillance systems, including standardized micronutrient deficiency diagnostic criteria, are vital for the control of micronutrient deficiency disease

    The XMM-LSS survey: the Class 1 cluster sample over the extended 11 deg2^2 and its spatial distribution

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    This paper presents 52 X-ray bright galaxy clusters selected within the 11 deg2^2 XMM-LSS survey. 51 of them have spectroscopic redshifts (0.05<z<1.060.05<z<1.06), one is identified at zphot=1.9z_{\rm phot}=1.9, and all together make the high-purity "Class 1" (C1) cluster sample of the XMM-LSS, the highest density sample of X-ray selected clusters with a monitored selection function. Their X-ray fluxes, averaged gas temperatures (median TX=2T_X=2 keV), luminosities (median LX,500=5×1043L_{X,500}=5\times10^{43} ergs/s) and total mass estimates (median 5×1013h1M5\times10^{13} h^{-1} M_{\odot}) are measured, adapting to the specific signal-to-noise regime of XMM-LSS observations. The redshift distribution of clusters shows a deficit of sources when compared to the cosmological expectations, regardless of whether WMAP-9 or Planck-2013 CMB parameters are assumed. This lack of sources is particularly noticeable at 0.4z0.90.4 \lesssim z \lesssim 0.9. However, after quantifying uncertainties due to small number statistics and sample variance we are not able to put firm (i.e. >3σ>3 \sigma) constraints on the presence of a large void in the cluster distribution. We work out alternative hypotheses and demonstrate that a negative redshift evolution in the normalization of the LXTXL_{X}-T_X relation (with respect to a self-similar evolution) is a plausible explanation for the observed deficit. We confirm this evolutionary trend by directly studying how C1 clusters populate the LXTXzL_{X}-T_X-z space, properly accounting for selection biases. We point out that a systematically evolving, unresolved, central component in clusters and groups (AGN contamination or cool core) can impact the classification as extended sources and be partly responsible for the observed redshift distribution.[abridged]Comment: 33 pages, 21 figures, 3 tables ; accepted for publication in MNRA

    Complete intersections: Moduli, Torelli, and good reduction

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    We study the arithmetic of complete intersections in projective space over number fields. Our main results include arithmetic Torelli theorems and versions of the Shafarevich conjecture, as proved for curves and abelian varieties by Faltings. For example, we prove an analogue of the Shafarevich conjecture for cubic and quartic threefolds and intersections of two quadrics.Comment: 37 pages. Typo's fixed. Expanded Section 2.

    The XXL Survey VII: A supercluster of galaxies at z=0.43

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    The XXL Survey is the largest homogeneous and contiguous survey carried out with XMM-Newton. Covering an area of 50 square degrees distributed over two fields, it primarily investigates the large-scale structures of the Universe using the distribution of galaxy clusters and active galactic nuclei as tracers of the matter distribution. Given its depth and sky coverage, XXL is particularly suited to systematically unveiling the clustering of X-ray clusters and to identifying superstructures in a homogeneous X-ray sample down to the typical mass scale of a local massive cluster. A friends-of-friends algorithm in three-dimensional physical space was run to identify large-scale structures. In this paper we report the discovery of the highest redshift supercluster of galaxies found in the XXL Survey. We describe the X-ray properties of the clusters members of the structure and the optical follow-up. The newly discovered supercluster is composed of six clusters of galaxies at a median redshift z around 0.43 and distributed across approximately 30 by 15 arc minutes (10 by 5 Mpc on sky) on the sky. This structure is very compact with all the clusters residing in one XMM pointing; for this reason this is the first supercluster discovered with the XXL Survey. Spectroscopic follow-up with WHT (William Herschel Telescope) and NTT (New Technology Telescope) confirmed a median redshift of z = 0.43. An estimate of the X-ray mass and luminosity of this supercluster and of its total gas mass put XLSSC-e at the average mass range of superclusters; its appearance, with two members of equal size, is quite unusual with respect to other superclusters and provides a unique view of the formation process of a massive structure.Comment: A&A, accepted; special XXL issu

    Dilation of the Giant Vortex State in a Mesoscopic Superconducting Loop

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    We have experimentally investigated the magnetisation of a mesoscopic aluminum loop at temperatures well below the superconducting transition temperature TcT_{c}. The flux quantisation of the superconducting loop was investigated with a μ\mu-Hall magnetometer in magnetic field intensities between ±100Gauss\pm 100 {Gauss}. The magnetic field intensity periodicity observed in the magnetization measurements is expected to take integer values of the superconducting flux quanta Φ0=h/2e\Phi_{0}=h/2e. A closer inspection of the periodicity, however, reveal a sub flux quantum shift. This fine structure we interpret as a consequence of a so called giant vortex state nucleating towards either the inner or the outer side of the loop. These findings are in agreement with recent theoretical reports.Comment: 12 pages, 5 figures. Accepted for publication in Phys. Rev.

    Invariants of Lie algebras extended over commutative algebras without unit

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    We establish results about the second cohomology with coefficients in the trivial module, symmetric invariant bilinear forms and derivations of a Lie algebra extended over a commutative associative algebra without unit. These results provide a simple unified approach to a number of questions treated earlier in completely separated ways: periodization of semisimple Lie algebras (Anna Larsson), derivation algebras, with prescribed semisimple part, of nilpotent Lie algebras (Benoist), and presentations of affine Kac-Moody algebras.Comment: v3: added a footnote on p.10 about a wrong derivation of the correct statemen
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