782 research outputs found

    Mapping the Asymmetric Thick Disk: II Distance, Size and Mass of the Hercules Thick Disk Cloud

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    The Hercules Thick Disk Cloud (Larsen et al. 2008) was initially discovered as an excess in the number of faint blue stars between quadrants 1 and 4 of the Galaxy. The origin of the Cloud could be an interaction with the disk bar, a triaxial thick disk or a merger remnant or stream. To better map the spatial extent of the Cloud along the line of sight, we have obtained multi-color UBVR photometry for 1.2 million stars in 63 fields approximately 1 square degree each. Our analysis of the fields beyond the apparent boundaries of the excess have already ruled out a triaxial thick disk as a likely explanation (Larsen, Humphreys and Cabanela 2010) In this paper we present our results for the star counts over all of our fields, determine the spatial extent of the over density across and along the line of sight, and estimate the size and mass of the Cloud. Using photometric parallaxes, the stars responsible for the excess are between 1 and 6 kiloparsecs from the Sun, 0.5 -- 4 kpc above the Galactic plane, and extends approximately 3-4 kiloparsecs across our line of sight. It is thus a major substructure in the Galaxy. The distribution of the excess along our sight lines corresponds with the density contours of the bar in the Disk, and its most distant stars are directly over the bar. We also see through the Cloud to its far side. Over the entire 500 square degrees of sky containing the Cloud, we estimate more than 5.6 million stars and 1.9 million solar masses of material. If the over density is associated with the bar, it would exceed 1.4 billion stars and more than than 50 million solar masses. Finally, we argue that the Hercules-Aquila Cloud (Belokurov et al. 2007) is actually the Hercules Thick Disk Cloud.Comment: 52 pages, 13 figure

    Symmetric tensor decomposition

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    We present an algorithm for decomposing a symmetric tensor, of dimension n and order d as a sum of rank-1 symmetric tensors, extending the algorithm of Sylvester devised in 1886 for binary forms. We recall the correspondence between the decomposition of a homogeneous polynomial in n variables of total degree d as a sum of powers of linear forms (Waring's problem), incidence properties on secant varieties of the Veronese Variety and the representation of linear forms as a linear combination of evaluations at distinct points. Then we reformulate Sylvester's approach from the dual point of view. Exploiting this duality, we propose necessary and sufficient conditions for the existence of such a decomposition of a given rank, using the properties of Hankel (and quasi-Hankel) matrices, derived from multivariate polynomials and normal form computations. This leads to the resolution of polynomial equations of small degree in non-generic cases. We propose a new algorithm for symmetric tensor decomposition, based on this characterization and on linear algebra computations with these Hankel matrices. The impact of this contribution is two-fold. First it permits an efficient computation of the decomposition of any tensor of sub-generic rank, as opposed to widely used iterative algorithms with unproved global convergence (e.g. Alternate Least Squares or gradient descents). Second, it gives tools for understanding uniqueness conditions, and for detecting the rank

    Microscopically-constrained Fock energy density functionals from chiral effective field theory. I. Two-nucleon interactions

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    The density matrix expansion (DME) of Negele and Vautherin is a convenient tool to map finite-range physics associated with vacuum two- and three-nucleon interactions into the form of a Skyme-like energy density functional (EDF) with density-dependent couplings. In this work, we apply the improved formulation of the DME proposed recently in arXiv:0910.4979 by Gebremariam {\it et al.} to the non-local Fock energy obtained from chiral effective field theory (EFT) two-nucleon (NN) interactions at next-to-next-to-leading-order (N2^2LO). The structure of the chiral interactions is such that each coupling in the DME Fock functional can be decomposed into a cutoff-dependent coupling {\it constant} arising from zero-range contact interactions and a cutoff-independent coupling {\it function} of the density arising from the universal long-range pion exchanges. This motivates a new microscopically-guided Skyrme phenomenology where the density-dependent couplings associated with the underlying pion-exchange interactions are added to standard empirical Skyrme functionals, and the density-independent Skyrme parameters subsequently refit to data. A Mathematica notebook containing the novel density-dependent couplings is provided.Comment: 28 pages, 12 figures. Mathematica notebook provided with submission

    Hydrogen-free SiCN films obtained by electron cyclotron resonance plasma: a study of composition, optical and luminescent properties

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    The Electrochemical Society, Inc. 2007. All rights reserved. Except as provided under U.S. copyright law, this work may not be reproduced, resold, distributed, or modified without the express permission of The Electrochemical Society (ECS). The archival version of this work was published in Journal of the Electrochemical Society Vol. 154 Issue 4 (2007): H325-H33

    “For Asia market only”: a green tattoo ink between safety and regulations

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    Due to the increasing tattoo practicing in Eastern countries and general concern on tattoo ink composition and safety, the green tattoo inks Green Concentrate by Eternal, for European and “for Asia Market Only” were analyzed, under the premise that only the former falls under a composition regulation. A separation of the additives from the pigment was carried out by successive extraction in solvents of different polarities, i.e., water, acetone and dichloromethane. The solid residues were analyzed by IR and Raman spectroscopies, the liquid fractions by GC/mass spectrometry. The relative pigment load and element traces were also estimated. We found that the European and the Asian inks are based on the same pigment, PG7, restricted in Europe, though at different loads. They have a similar content of harmful impurities, such as Ni, As, Cd and Sb and both contain siloxanes, including harmful D4. Furthermore, they have different physical-chemical properties, the European ink being more hydrophilic, the Asian more hydrophobic. Additionally, the Asian ink contains harmful additives for the solubilization of hydrophobic matrices and by-products of the phthalocyanine synthesis. Teratogenic phthalates are present as well as chlorinated teratogenic and carcinogenic compounds usually associated to the laser treatment for removal purposes, to a larger extent in the European ink. The composition of the inks does not seem to reflect regulatory restrictions, where issued

    Laboratory chemical waste: hazard classification by GHS and transport risk

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    OBJETIVOS: Identificar e avaliar, com base no Sistema Globalmente Harmonizado de Classificação e Rotulagem de Produtos Químicos (GHS) e na legislação da Agência Nacional de Transportes Terrestres (ANTT), os perigos provenientes dos resíduos químicos gerados em laboratórios de pesquisa na área de saúde. MÉTODOS: Resíduos químicos gerados em dois Laboratórios de Investigação Médica da Faculdade de Medicina da Universidade de São Paulo foram inventariados, no período de novembro de 2017 a abril de 2019, e classificados conforme o GHS (frases de perigo) e a legislação de transportes da ANTT (classes de risco), para determinação dos perigos provenientes das respectivas substâncias e misturas. RESULTADOS: No total, foram identificadas 40 substâncias ou misturas, cuja classificação pelo GHS indicou 36 frases de perigo, sendo 27 relacionadas à saúde humana. De acordo com a legislação estabelecida pela ANTT, foram encontrados 16 casos de periculosidade associada à inflamabilidade, 15 casos relacionados à toxicidade e 12 casos relativos à corrosividade. CONCLUSÕES: Resíduos químicos gerados nos laboratórios estudados são diversificados quanto a suas características de periculosidade, implicando a possibilidade de exposição a riscos severos aos trabalhadores, aos estudantes e ao ambiente. A correta identificação desses resíduos é fator primordial para diminuição da exposição aos riscos.OBJECTIVES: To identify and evaluate, based on the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) and the legislation of the Agência Nacional de Transportes Terrestres (ANTT – National Agency for Terrestrial Transport), the hazards arising from chemical waste generated in research laboratories in the health area. METHODS: Chemical residues generated in two medical research laboratories of the Faculdade de Medicina da Universidade de São Paulo were inventoried, from November 2017 to April 2019, and classified according to the GHS (hazard statements) and the ANTT transport legislation (risk classes), to determine the dangers coming from the respective substances and mixtures. RESULTS: In total, we identified 40 substances or mixtures with classification by the GHS indicating 36 hazard statements, 27 of which related to human health. According to the legislation established by ANTT, we found 16 cases of hazard associated with flammability, 15 cases related to toxicity and 12 cases related to corrosivity. CONCLUSIONS: Chemical residues generated in the laboratories studied are diversified in terms of their hazard characteristics, implying the possibility of exposure to severe risks to workers, students and the environment. The correct identification of these residues is a primary factor for reducing exposure to risks

    Role of Staphylococcus aureus GapC and GapB in immunity and pathogenesis of bovine mastitis

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    Mastitis is the most prevalent and major cause of economic losses in dairy farms. Bovine mastitis caused by strains of S. aureus is a major economically important disease affecting the dairy industry worldwide. S. aureus is one of the most common udder pathogens that cause either clinical or sub-clinical mammary gland infections. Different treatment regimes have failed to cure S. aureus intramammary infections. Most mastitis vaccination strategies have focused on the enhancement of systemic humoral immunity rather than strengthening local intramammary immunity. Vaccines aimed at enhancing intramammary immunity of dairy cows against S. aureus mastitis have had limited success. Commercially available vaccines show various degrees of success and work in research laboratories with experimental vaccines suggest that in part, the failure of these vaccines lies in the limited antigenic repertoire contained in the vaccine formulations. Moreover, not only does variation in the antigenic composition but also presence of capsular polysaccharide in most pathogenic strains and decreased activity of immune effectors in milk affect the success of vaccines. In addition to these, the ability of S. aureus to attach and internalize into mammary epithelial cells, enables bacteria to escape from the effect of immunity and antibiotics by being hidden in the intracellular niche and thereby causing chronic recurrent intramammary infection. S. aureus also has the ability to become electron-transport-defective and to form slow-growing small colonies that are non haemolytic and less virulent. These small colony variants might hide from the immune surveillance in the intracellular area and revert to the parental strain causing chronic recurrent infections. If immunization targets antigenic molecules that are conserved throughout all pathogenic strains, even the small colony variants can be controlled since the immune system will clear the parental strain which causes lethal infection. Thus, immunization trials should focus on conserved immunogenic antigen molecules among pathogenic strains formulated with an adjuvant and delivered by a route of immunization to induce maximum stimulation of the immune system. Moreover, immunization should focus on inducing Th1 responses, which is protective against S. aureus mastitis. It has been reported that proteins with glyceraldehyde-3-phosphate dehydrogenase (GAPDH) activity might be used as such antigens to induce protection against parasitic and microbial infections. Previous study in our laboratory on mastitis-causing streptococci indicates that GapC proteins of S. uberis and S. dysgalactiae have potential as vaccine antigens to protect dairy cows against mastitis caused by environmental streptococci. Two conserved cell wall associated proteins with iii glyceraldehyde-3-phosphate dehydrogenase (GAPDH) activity, GapB and GapC have been identified from S. aureus isolates from bovine intramammary infections. The overall goal of this study was to improve our understanding on intramammary immunity using the GapC and GapB proteins of S. aureus as model antigens for mastitis and to determine the regulation of expression of gapB and gapC genes and their roles in the pathogenesis of bovine S. aureus mastitis. We hypothesized that strengthening local intramammary immunity using GapB and GapC proteins of S. aureus as antigens will protect against bovine S. aureus mastitis. To test this hypothesis we took the approach of using the gapB and gapC genes and constructed plasmids encoding GapB, GapC and GapB::GapC (GapC/B) chimeric proteins. We set six objectives to test our hypothesis using these proteins to enhance the intramammary immunity. In aim 1 we constructed plasmids encoding the GapB, GapC proteins and also constructed a chimeric gene encoding the GapC and GapB proteins as a single entity (GapC/B chimera) as the basis for a multivalent vaccine. In this objective the humoral and cellular immune responses to GapC/B were compared to the responses to the individual proteins alone or in combination in C57 BL/6 mice. Our results showed that the GapC/B protein elicited strong humoral and cellular immune responses as judged by the levels of total IgG, IgG1, IgG2a, IL-4 and IFN-ã secretion and lymphocyte proliferation. These results strongly suggest the potential of this chimeric protein as a target for vaccine production to control mastitis caused by S. aureus. In aim 2 we continued our studies on GapC/B by testing the effects of DNA vaccination with plasmids encoding the individual gapB and gapC genes as well as the gapC/B protein gene with or without a boost with the recombinant proteins. The results showed that DNA vaccination alone was unable to elicit a significant humoral response and barely able to elicit a detectable cell-mediated response to the recombinant antigens but subsequent immunization with the proteins elicited an excellent response. In addition, we found that DNA vaccination using a plasmid encoding the GapC/B chimera followed by a boost with the same protein, although successful, is less effective than priming with plasmids encoding GapB or GapC followed by a boost with the individual antigens. In aim 3 we optimized immune responses in cows by comparing route of vaccination (subcutaneous versus intradermal), site of vaccination (locally at the area drained by the supramammary lymph node versus distantly at area drained by parotid lymph node. Our results showed that both subcutaneous and intradermal immunizations with the GapC/B protein at the area drained by the supramammary and parotid lymph nodes resulted in significantly increased serum and milk titers of total IgG, IgG1, IgG2, iv and IgA in all vaccinated groups as compared to placebo. The anti-GapC/B IgG1 serum and milk titers were significantly higher in all vaccinated group as compared to the placebo group. These results indicated that vaccination at the area drained by the supramammary lymph node resulted in better immune responses. In aim 4 we tested different formulations of the GapC/B antigen with adjuvants such as PCPP, CpG, PCPP + CpG and VSA-3. We found that the VSA-3 formulation induced the best immune responses in cows. In this objective we also monitored immune responses longitudinally over one lactation cycle to determine the duration of immune responses by measuring IgG, IgG1, IgG2, and IgA on monthly blood and milk samples. We found that the duration of immune responses was about four months. In aim 5 we tested the role of GapC in the virulence of S. aureus mastitis using the S. aureus wild type strain RN6390 and its isogenic GapC mutant strain H330. Our results from both in vitro adhesion and invasion assays on MAC- T cells and in vivo infection of ovine mammary glands showed that GapC is an important virulence factor in S. aureus mastitis. In aim 6 we examined the role of sar and agr loci on the expression of gapC and gapB genes by qRT- PCR using S. aureus RN6390 and its isogenic mutants defective in agrA, sarA and sar/agr (double mutant) at exponential and stationary phases of growth. Our results showed that both gapB and gapC expression were down regulated in the mutant strains, indicating that the expression of the gapB and gapC genes is controlled by the universal virulence gene regulators, agr and sar. We also checked the role of environmental factors such as pH, growth media, and oxygen tension on the expression of gapB and gapC using q-RT-PCR. Our results showed that the expression of gapB and gapC genes in different strains of S. aureus was not consistent under the above-mentioned environmental conditions

    Mapping the Asymmetric Thick Disk I. A Search for Triaxiality

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    A significant asymmetry in the distribution of faint blue stars in the inner Galaxy, Quadrant 1 (l = 20 to 45 degrees) compared to Quadrant 4 was first reported by Larsen & Humphreys (1996). Parker et al (2003, 2004) greatly expanded the survey to determine its spatial extent and shape and the kinematics of the affected stars. This excess in the star counts was subsequently confirmed by Juric et al. (2008) using SDSS data. Possible explanations for the asymmetry include a merger remnant, a triaxial Thick Disk, and a possible interaction with the bar in the Disk. In this paper we describe our program of wide field photometry to map the asymmetry to fainter magnitudes and therefore larger distances. To search for the signature of triaxiality, we extended our survey to higher Galactic longitudes. We find no evidence for an excess of faint blue stars at l > 55 degrees including the faintest magnitude interval. The asymmetry and star count excess in Quadrant 1 is thus not due to a triaxial Thick Disk.Comment: 36 pages, 8 figures. Accepted by Astronomical Journa

    On the homotopy groups of E(n)-local spectra with unusual invariant ideals

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    Let E(n) and T(m) for nonnegative integers n and m denote the Johnson-Wilson and the Ravenel spectra, respectively. Given a spectrum whose E(n)_*-homology is E(n)_*(T(m))/(v_1,...,v_{n-1}), then each homotopy group of it estimates the order of each homotopy group of L_nT(m). We here study the E(n)-based Adams E_2-term of it and present that the determination of the E_2-term is unexpectedly complex for odd prime case. At the prime two, we determine the E_{infty}-term for pi_*(L_2T(1)/(v_1)), whose computation is easier than that of pi_*(L_2T(1)) as we expect.Comment: This is the version published by Geometry & Topology Monographs on 18 April 200
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