387 research outputs found

    Obliquity of an Earth-like planet from frequency modulation of its direct imaged lightcurve: mock analysis from general circulation model simulation

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    Direct-imaging techniques of exoplanets have made significant progress recently, and will eventually enable to monitor photometric and spectroscopic signals of earth-like habitable planets in the future. The presence of clouds, however, would remain as one of the most uncertain components in deciphering such direct-imaged signals of planets. We attempt to examine how the planetary obliquity produce different cloud patterns by performing a series of GCM (General Circulation Model) simulation runs using a set of parameters relevant for our Earth. Then we use the simulated photometric lightcurves to compute their frequency modulation due to the planetary spin-orbit coupling over an entire orbital period, and attempt to see to what extent one can estimate the obliquity of an Earth-twin. We find that it is possible to estimate the obliquity of an Earth-twin within the uncertainty of several degrees with a dedicated 4 m space telescope at 10 pc away from the system if the stellar flux is completely blocked. While our conclusion is based on several idealized assumptions, a frequency modulation of a directly-imaged earth-like planet offers a unique methodology to determine its obliquity.Comment: 29 pages, 18 figures, accepted for publication in Ap

    Can Admission and Fasting Glucose Reliably Identify Undiagnosed Diabetes in Patients With Acute Coronary Syndrome?

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    OBJECTIVE—Our objectives were to determine the prevalence of previously undiagnosed abnormal glucose tolerance, i.e., diabetes and impaired glucose tolerance (IGT) in patients with acute coronary syndrome and to assess the utility of admission and fasting glucose in identifying diabetes in these patients

    Evidence for the Mitochondrial Lactate Oxidation Complex in Rat Neurons: Demonstration of an Essential Component of Brain Lactate Shuttles

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    To evaluate the presence of components of a putative Intracellular Lactate Shuttle (ILS) in neurons, we attempted to determine if monocarboxylate (e.g. lactate) transporter isoforms (MCT1 and -2) and lactate dehydrogenase (LDH) are coexpressed in neuronal mitochondria of rat brains. Immunohistochemical analyses of rat brain cross-sections showed MCT1, MCT2, and LDH to colocalize with the mitochondrial inner membrane marker cytochrome oxidase (COX) in cortical, hippocampal, and thalamic neurons. Immunoblotting after immunoprecipitation (IP) of mitochondria from brain homogenates supported the histochemical observations by demonstrating that COX coprecipitated MCT1, MCT2, and LDH. Additionally, using primary cultures from rat cortex and hippocampus as well as immunohistochemistry and immunocoprecipitation techniques, we demonstrated that MCT2 and LDH are coexpressed in mitochondria of cultured neurons. These findings can be interpreted to mean that, as in skeletal muscle, neurons contain a mitochondrial lactate oxidation complex (mLOC) that has the potential to facilitate both intracellular and cell-cell lactate shuttles in brain

    Deficiency and Also Transgenic Overexpression of Timp-3 Both Lead to Compromised Bone Mass and Architecture In Vivo

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    Tissue inhibitor of metalloproteinases-3 (TIMP-3) regulates extracellular matrix via its inhibition of matrix metalloproteinases and membrane-bound sheddases. Timp-3 is expressed at multiple sites of extensive tissue remodelling. This extends to bone where its role, however, remains largely unresolved. In this study, we have used Micro-CT to assess bone mass and architecture, histological and histochemical evaluation to characterise the skeletal phenotype of Timp-3 KO mice and have complemented this by also examining similar indices in mice harbouring a Timp-3 transgene driven via a Col-2a-driven promoter to specifically target overexpression to chondrocytes. Our data show that Timp-3 deficiency compromises tibial bone mass and structure in both cortical and trabecular compartments, with corresponding increases in osteoclasts. Transgenic overexpression also generates defects in tibial structure predominantly in the cortical bone along the entire shaft without significant increases in osteoclasts. These alterations in cortical mass significantly compromise predicted tibial load-bearing resistance to torsion in both genotypes. Neither Timp-3 KO nor transgenic mouse growth plates are significantly affected. The impact of Timp-3 deficiency and of transgenic overexpression extends to produce modification in craniofacial bones of both endochondral and intramembranous origins. These data indicate that the levels of Timp-3 are crucial in the attainment of functionally-appropriate bone mass and architecture and that this arises from chondrogenic and osteogenic lineages

    Galaxy Clusters Selected with the Sunyaev-Zel'dovich Effect from 2008 South Pole Telescope Observations

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    We present a detection-significance-limited catalog of 21 Sunyaev-Zel'dovich selected galaxy clusters. These clusters, along with 1 unconfirmed candidate, were identified in 178 deg^2 of sky surveyed in 2008 by the South Pole Telescope to a depth of 18 uK-arcmin at 150 GHz. Optical imaging from the Blanco Cosmology Survey (BCS) and Magellan telescopes provided photometric (and in some cases spectroscopic) redshift estimates, with catalog redshifts ranging from z=0.15 to z>1, with a median z = 0.74. Of the 21 confirmed galaxy clusters, three were previously identified as Abell clusters, three were presented as SPT discoveries in Staniszewski et al, 2009, and three were first identified in a recent analysis of BCS data by Menanteau et al, 2010; the remaining 12 clusters are presented for the first time in this work. Simulated observations of the SPT fields predict the sample to be nearly 100% complete above a mass threshold of M_200 ~ 5x10^14 M_sun/h at z = 0.6. This completeness threshold pushes to lower mass with increasing redshift, dropping to ~4x10^14 M_sun/h at z=1. The size and redshift distribution of this catalog are in good agreement with expectations based on our current understanding of galaxy clusters and cosmology. In combination with other cosmological probes, we use the cluster catalog to improve estimates of cosmological parameters. Assuming a standard spatially flat wCDM cosmological model, the addition of our catalog to the WMAP 7-year analysis yields sigma_8 = 0.81 +- 0.09 and w = -1.07 +- 0.29, a ~50% improvement in precision on both parameters over WMAP7 alone.Comment: 19 pages, 9 figures, 4 appendice

    Antibodies Against β2-Glycoprotein I Complexed With an Oxidised Lipoprotein Relate to Intima Thickening of Carotid Arteries in Primary Antiphospholipid Syndrome

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    To explore whether antibodies against β2-glycoprotein I (β2GPI) complexed to 7-ketocholesteryl-9-carboxynonanoate (oxLig-1) and to oxidised low-density lipoproteins (oxLDL) relate to paraoxonase activity (PONa) and/or intima media thickness (IMT) of carotid arteries in primary antiphospholipid syndrome (PAPS). As many as 29 thrombotic patients with PAPS, 10 subjects with idiopathic antiphospholipid antibodies (aPL) without thrombosis, 17 thrombotic patients with inherited thrombophilia and 23 healthy controls were investigated. The following were measured in all participants: β2GPI−oxLDL complexes, IgG anti-β2GPI−oxLig-1, IgG anti-β2GPI−oxLDL antibodies (ELISA), PONa, (para-nitrophenol method), IMT of common carotid (CC) artery, carotid bifurcation (B), internal carotid (IC) by high resolution sonography. β2GPI−oxLDL complex was highest in the control group (p < 0.01), whereas, IgG anti-β2GPI−oxLig1 and IgG anti-β2GPI−oxLDL were highest in PAPS (p < 0.0001). In healthy controls, β2GPI−oxLDL complexes positively correlated to IMT of the IC (p = 0.007) and negatively to PONa after correction for age (p < 0.03). PONa inversely correlated with age (p = 0.008). In PAPS, IgG anti-2GPI−oxLig-1 independently predicted PONa (p = 0.02) and IMT of B (p = 0.003), CC, (p = 0.03) and of IC (p = 0.04). In PAPS, PONa inversely correlated to the IMT of B, CC and IC (p = 0.01, 0.02 and 0.003, respectively). IgG anti-2GPI−oxLig-1 may be involved in PAPS related atherogenesis via decreased PON activity

    Catching Element Formation In The Act

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    Gamma-ray astronomy explores the most energetic photons in nature to address some of the most pressing puzzles in contemporary astrophysics. It encompasses a wide range of objects and phenomena: stars, supernovae, novae, neutron stars, stellar-mass black holes, nucleosynthesis, the interstellar medium, cosmic rays and relativistic-particle acceleration, and the evolution of galaxies. MeV gamma-rays provide a unique probe of nuclear processes in astronomy, directly measuring radioactive decay, nuclear de-excitation, and positron annihilation. The substantial information carried by gamma-ray photons allows us to see deeper into these objects, the bulk of the power is often emitted at gamma-ray energies, and radioactivity provides a natural physical clock that adds unique information. New science will be driven by time-domain population studies at gamma-ray energies. This science is enabled by next-generation gamma-ray instruments with one to two orders of magnitude better sensitivity, larger sky coverage, and faster cadence than all previous gamma-ray instruments. This transformative capability permits: (a) the accurate identification of the gamma-ray emitting objects and correlations with observations taken at other wavelengths and with other messengers; (b) construction of new gamma-ray maps of the Milky Way and other nearby galaxies where extended regions are distinguished from point sources; and (c) considerable serendipitous science of scarce events -- nearby neutron star mergers, for example. Advances in technology push the performance of new gamma-ray instruments to address a wide set of astrophysical questions.Comment: 14 pages including 3 figure

    Synthetic Toll Like Receptor-4 (TLR-4) Agonist Peptides as a Novel Class of Adjuvants

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    Background: Adjuvants serve as catalysts of the innate immune response by initiating a localized site of inflammation that is mitigated by the interactions between antigens and toll like receptor (TLR) proteins. Currently, the majority of vaccines are formulated with aluminum based adjuvants, which are associated with various side effects. In an effort to develop a new class of adjuvants, agonists of TLR proteins, such as bacterial products, would be natural candidates. Lipopolysaccharide (LPS), a major structural component of gram negative bacteria cell walls, induces the systemic inflammation observed in septic shock by interacting with TLR-4. The use of synthetic peptides of LPS or TLR-4 agonists, which mimic the interaction between TLR-4 and LPS, can potentially regulate cellular signal transduction pathways such that a localized inflammatory response is achieved similar to that generated by adjuvants. Methodology/Principal Findings: We report the identification and activity of several peptides isolated using phage display combinatorial peptide technology, which functionally mimicked LPS. The activity of the LPS-TLR-4 interaction was assessed by NF-kB nuclear translocation analyses in HEK-BLUE TM-4 cells, a cell culture model that expresses only TLR-4, and the murine macrophage cell line, RAW264.7. Furthermore, the LPS peptide mimics were capable of inducing inflammatory cytokine secretion from RAW264.7 cells. Lastly, ELISA analysis of serum from vaccinated BALB/c mice revealed that the LPS peptide mimics act as a functional adjuvant
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