82 research outputs found

    The Nature of Superfluidity in Ultracold Fermi Gases Near Feshbach Resonances

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    We study the superfluid state of atomic Fermi gases using a BCS-BEC crossover theory. Our approach emphasizes non-condensed fermion pairs which strongly hybridize with their (Feshbach-induced) molecular boson counterparts. These pairs lead to pseudogap effects above TcT_c and non-BCS characteristics below. We discuss how these effects influence the experimental signatures of superfluidity.Comment: 4 pages, 3 figures, submitted to PRA Rapid Communications; introduction rewritten, figure replace

    The First Brown Dwarf Discovered by the Backyard Worlds: Planet 9 Citizen Science Project

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    The Wide-field Infrared Survey Explorer (WISE) is a powerful tool for finding nearby brown dwarfs and searching for new planets in the outer solar system, especially with the incorporation of NEOWISE and NEOWISE-Reactivation data. So far, searches for brown dwarfs in WISE data have yet to take advantage of the full depth of the WISE images. To efficiently search this unexplored space via visual inspection, we have launched a new citizen science project, called "Backyard Worlds: Planet 9," which asks volunteers to examine short animations composed of difference images constructed from time-resolved WISE coadds. We report the discovery of the first new substellar object found by this project, WISEA J110125.95+540052.8, a T5.5 brown dwarf located approximately 34 pc from the Sun with a total proper motion of \sim0.7 as yr1^{-1}. WISEA J110125.95+540052.8 has a WISE W2W2 magnitude of W2=15.37±0.09W2=15.37 \pm 0.09, this discovery demonstrates the ability of citizen scientists to identify moving objects via visual inspection that are 0.9 magnitudes fainter than the W2W2 single-exposure sensitivity, a threshold that has limited prior motion-based brown dwarf searches with WISE.Comment: 9 pages, 4 figures, 1 table. Accepted for publication in the Astrophysical Journal Letter

    PHYSICAL AND CHEMICAL PROPERTIES OF SOIL IN FRUIT GROWING AREA TOPOLA (SERBIA)

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    The aim of the investigation was to assess the level of soil fertility and repair measures in order to enhance the productivity of fruit production in a traditional fruit growing area. (Municipality of Topola, Serbia). The following tests were performed: mechanical composition, physical and chemical properties of soil, total adsorbed base cation, capacity of adsorbed base cation, degree of base saturation, different types of soil acidity, contents of carbon, humus, total nitrogen, easily accessible forms of P2O5 and K2O. Results obtained have shown that soils from all studied sites are of “heavy” mechanical texture with 75,40-84,90% of physical clay. High capacity of cation adsorption, low to medium hydrolytic acidity and high to almost complete saturation of adsorbed bases, has been measured. In compliance with previous analyses, it has been assessed that soils are neutral and of low acid chemical reaction, with low carbon and medium humus content and total nitrogen. Easily accessible content of P2O5 and K2O varies depending on the food quantity on individual parcels with low to medium accessibility to parcels with no fruit plantations. Based on the parameters analysed, the tested soils demand repair of mechanical properties, which will facilitate greater nutrient uptake

    The pseudogap state in superconductors: Extended Hartree approach to time-dependent Ginzburg-Landau Theory

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    It is well known that conventional pairing fluctuation theory at the Hartree level leads to a normal state pseudogap in the fermionic spectrum. Our goal is to extend this Hartree approximated scheme to arrive at a generalized mean field theory of pseudogapped superconductors for all temperatures TT. While an equivalent approach to the pseudogap has been derived elsewhere using a more formal Green's function decoupling scheme, in this paper we re-interpret this mean field theory and BCS theory as well, and demonstrate how they naturally relate to ideal Bose gas condensation. Here we recast the Hartree approximated Ginzburg-Landau self consistent equations in a T-matrix form. This recasting makes it possible to consider arbitrarily strong attractive coupling, where bosonic degrees of freedom appear at T T^* considerably above TcT_c. The implications for transport both above and below TcT_c are discussed. Below TcT_c we find two types of contributions. Those associated with fermionic excitations have the usual BCS functional form. That they depend on the magnitude of the excitation gap, nevertheless, leads to rather atypical transport properties in the strong coupling limit, where this gap (as distinct from the order parameter) is virtually TT-independent. In addition, there are bosonic terms arising from non-condensed pairs whose transport properties are shown here to be reasonably well described by an effective time-dependent Ginzburg-Landau theory.Comment: 14 pages, 5 figures, REVTeX4, submitted to PRB; clarification of the diagrammatic technique added, one figure update

    Cancer data and Aboriginal disparities (CanDAD)-developing an Advanced Cancer Data System for Aboriginal people in South Australia: a mixed methods research protocol

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    Introduction: In Australia, Aboriginal and Torres Strait Islander People carry a greater burden of cancerrelated mortality than non-Aboriginal Australians. The Cancer Data and Aboriginal Disparities Project aims to develop and test an integrated, comprehensive cancer monitoring and surveillance system capable of incorporating epidemiological and narrative data to address disparities and advocate for clinical system change. Methods and analysis: The Advanced Cancer Data System will integrate routinely collected unit record data from the South Australian Population Cancer Registry and a range of other data sources for a retrospective cohort of indigenous people with cancers diagnosed from 1990 to 2010. A randomly drawn non- Aboriginal cohort will be matched by primary cancer site, sex, age and year at diagnosis. Cross-tabulations and regression analyses will examine the extent to which demographic attributes, cancer stage and survival vary between the cohorts. Narratives from Aboriginal people with cancer, their families, carers and service providers will be collected and analysed using patient pathway mapping and thematic analysis. Statements from the narratives will structure both a concept mapping process of rating, sorting and prioritising issues, focusing on issues of importance and feasibility, and the development of a real-time Aboriginal Cancer Measure of Experience for ongoing linkage with epidemiological data in the Advanced Cancer Data System. Aboriginal Community engagement underpins this Project. Ethics and dissemination: The research has been approved by relevant local and national ethics committees. Findings will be disseminated in local and international peer-reviewed journals and conference presentations. In addition, the research will provide data for knowledge translation activities across the partner organisations and feed directly into the Statewide Cancer Control Plan. It will provide a mechanism for monitoring and evaluating the implementation of the recommendations in these documents.Paul Henry Yerrell, David Roder, Margaret Cargo, Rachel Reilly, David Banham, Jasmine May Micklem, Kim Morey, Harold Bundamurra Stewart, Janet Stajic, Michael Norris, Alex Brown, On behalf of the CanDAD Aboriginal Community Reference Group and CanDAD Investigator

    Direct Observation of the Superfluid Phase Transition in Ultracold Fermi Gases

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    Water freezes into ice, atomic spins spontaneously align in a magnet, liquid helium becomes superfluid: Phase transitions are dramatic phenomena. However, despite the drastic change in the system's behaviour, observing the transition can sometimes be subtle. The hallmark of Bose-Einstein condensation (BEC) and superfluidity in trapped, weakly interacting Bose gases is the sudden appearance of a dense central core inside a thermal cloud. In strongly interacting gases, such as the recently observed fermionic superfluids, this clear separation between the superfluid and the normal parts of the cloud is no longer given. Condensates of fermion pairs could be detected only using magnetic field sweeps into the weakly interacting regime. The quantitative description of these sweeps presents a major theoretical challenge. Here we demonstrate that the superfluid phase transition can be directly observed by sudden changes in the shape of the clouds, in complete analogy to the case of weakly interacting Bose gases. By preparing unequal mixtures of the two spin components involved in the pairing, we greatly enhance the contrast between the superfluid core and the normal component. Furthermore, the non-interacting wings of excess atoms serve as a direct and reliable thermometer. Even in the normal state, strong interactions significantly deform the density profile of the majority spin component. We show that it is these interactions which drive the normal-to-superfluid transition at the critical population imbalance of 70(5)%.Comment: 16 pages (incl. Supplemental Material), 5 figure

    Fermionic superfluidity: From high Tc superconductors to ultracold Fermi gases

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    We present a pairing fluctuation theory which self-consistently incorporates finite momentum pair excitations in the context of BCS--Bose-Einstein condensation (BEC) crossover, and we apply this theory to high TcT_c superconductors and ultracold Fermi gases. There are strong similarities between Fermi gases in the unitary regime and high Tc superconductors. Here we address key issues of common interest, especially the pseudogap. In the Fermi gases we summarize recent experiments including various phase diagrams (with and without population imbalance), as well as evidence for a pseudogap in thermodynamic and other experiments.Comment: Expanded version, invited talk at the 5th International Conference on Complex Matter -- Stripes 2006, 6 pages, 6 figure

    Whole Exome Sequencing of Patients with Steroid-Resistant Nephrotic Syndrome

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    BACKGROUND AND OBJECTIVES: Steroid-resistant nephrotic syndrome overwhelmingly progresses to ESRD. More than 30 monogenic genes have been identified to cause steroid-resistant nephrotic syndrome. We previously detected causative mutations using targeted panel sequencing in 30% of patients with steroid-resistant nephrotic syndrome. Panel sequencing has a number of limitations when compared with whole exome sequencing. We employed whole exome sequencing to detect monogenic causes of steroid-resistant nephrotic syndrome in an international cohort of 300 families. DESIGN, SETTING, PARTIIPANTS AND MEASUREMENTS: Three hundred thirty-five individuals with steroid-resistant nephrotic syndrome from 300 families were recruited from April of 1998 to June of 2016. Age of onset was restricted to <25 years of age. Exome data were evaluated for 33 known monogenic steroid-resistant nephrotic syndrome genes. RESULTS: In 74 of 300 families (25%), we identified a causative mutation in one of 20 genes known to cause steroid-resistant nephrotic syndrome. In 11 families (3.7%), we detected a mutation in a gene that causes a phenocopy of steroid-resistant nephrotic syndrome. This is consistent with our previously published identification of mutations using a panel approach. We detected a causative mutation in a known steroid-resistant nephrotic syndrome gene in 38% of consanguineous families and in 13% of nonconsanguineous families, and 48% of children with congenital nephrotic syndrome. A total of 68 different mutations were detected in 20 of 33 steroid-resistant nephrotic syndrome genes. Fifteen of these mutations were novel. NPHS1, PLCE1, NPHS2, and SMARCAL1 were the most common genes in which we detected a mutation. In another 28% of families, we detected mutations in one or more candidate genes for steroid-resistant nephrotic syndrome. CONCLUSIONS: Whole exome sequencing is a sensitive approach toward diagnosis of monogenic causes of steroid-resistant nephrotic syndrome. A molecular genetic diagnosis of steroid-resistant nephrotic syndrome may have important consequences for the management of treatment and kidney transplantation in steroid-resistant nephrotic syndrome

    Schimke immunoosseous dysplasia: defining skeletal features

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    Schimke immunoosseous dysplasia (SIOD) is an autosomal recessive multisystem disorder characterized by prominent spondyloepiphyseal dysplasia, T cell deficiency, and focal segmental glomerulosclerosis. Biallelic mutations in swi/snf-related, matrix-associated, actin-dependent regulator of chromatin, subfamily a-like 1 (SMARCAL1) are the only identified cause of SIOD, but approximately half of patients referred for molecular studies do not have detectable mutations in SMARCAL1. We hypothesized that skeletal features distinguish between those with or without SMARCAL1 mutations. Therefore, we analyzed the skeletal radiographs of 22 patients with and 11 without detectable SMARCAL1 mutations. We found that patients with SMARCAL1 mutations have a spondyloepiphyseal dysplasia (SED) essentially limited to the spine, pelvis, capital femoral epiphyses, and possibly the sella turcica, whereas the hands and other long bones are basically normal. Additionally, we found that several of the adolescent and young adult patients developed osteoporosis and coxarthrosis. Of the 11 patients without detectable SMARCAL1 mutations, seven had a SED indistinguishable from patients with SMARCAL1 mutations. We conclude therefore that SED is a feature of patients with SMARCAL1 mutations and that skeletal features do not distinguish who of those with SED have SMARCAL1 mutations
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