10,453 research outputs found

    The Asymmetric Thick Disk: A Star Count and Kinematic Analysis. II The Kinematics

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    We report a kinematic signature associated with the observed asymmetry in the distribution of thick disk/inner halo stars interior to the Solar circle described in Paper I. In that paper we found a statistically significant excess (20% to 25 %) of stars in quadrant I (l ~ 20 deg to 55 deg) both above and below the plane (b ~ +/- 25 deg to +/- 45 deg) compared to the complementary region in quadrant IV. We have measured Doppler velocities for 741 stars, selected according to the same magnitude and color criteria, in the direction of the asymmetry and in the corresponding fields in quadrant IV. We have also determined spectral types and metallicities measured from the same spectra. We not only find an asymmetric distribution in the V_LSR velocities for the stars in the two regions, but the angular rate of rotation, w, for the stars in quadrant I reveals a slower effective rotation rate compared to the corresponding quadrant IV stars. We use our [Fe/H] measurements to separate the stars into the three primary population groups, halo, thick disk, and disk, and conclude that it is primarily the thick disk stars that show the slower rotation in quadrant I. A solution for the radial, tangential and vertical components of the V_LSR velocities, reveals a significant lag of ~ 80 to 90 km/s in the direction of Galactic rotation for the thick disk stars in quadrant I, while in quadrant IV, the same population has only a ~ 20 km/s lag. The results reported here support a rotational lag among the thick disk stars due to a gravitational interaction with the bar as the most likely explanation for the asymmetry in both the star counts and the kinematics. The affected thick disk stars, however, may be associated with the recently discovered Canis Major debris stream or a similar merger event (abridged).Comment: Accepted for publication in the Astronomical Journa

    Effect of Aqueous Ozone on the NF-ÎşB System

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    Ozone has been proposed as an alternative oral antiseptic in dentistry, due to its antimicrobial power reported for gaseous and aqueous forms, the latter showing a high biocompatibility with mammalian cells. New therapeutic strategies for the treatment of periodontal disease and apical periodontitis should consider not only antibacterial effects, but also their influence on the host immune response. Therefore, our aim was to investigate the effect of aqueous ozone on the NF-ÎşB system, a paradigm for inflammationassociated signaling/transcription. We showed that NF-ÎşB activity in oral cells stimulated with TNF, and in periodontal ligament tissue from root surfaces of periodontally damaged teeth, was inhibited following incubation with ozonized medium. Under this treatment, IÎşBalpah proteolysis, cytokine expression, and ÎşB-dependent transcription were prevented. Specific ozonized amino acids were shown to represent major inhibitory components of ozonized medium. In summary, our study establishes a condition under which aqueous ozone exerts inhibitory effects on the NF-ÎşB system, suggesting that it has an antiinflammatory capacity

    Coccolith Morphology and Paleoclimatology - 2. Cell Ultrastructure and Formation of Coccoliths in Cyclococcolithina leptopora (Murray and Blackman) Wilcoxon and Gephyrocapsa oceanica Kamptner.

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    Current interest in utilization of coccoliths for paleoclimate reconstruction necessitates background information on environmental limits for growth and coccolith production as well as examination of cell ultrastructure in specimens collected in the field and in cultured representatives. Successful isolation of the two geologically important species Gephyrocapsa oceanica (strain A674) and Cyclococcolithina leptopora (strain A650) allows investigation of ultrastructure in cultured forms. Fine structure of cells and coccoliths was observed in the SEM using critical point dried preparations and ultrastructure was examined with the transmission electron microscope. Coccoliths are formed intracellularly and appear to form within Golgi-derived vesicles located near the nuclear membrane. Formation and development of coccoliths in the two species resemble these processes in Emiliania huxleyi but differ from those of Cricosphaera carterae, notably in the absence of coccolithosomes and scales and in the fact that coccoliths are produced intracellularly one at a time

    Evidence for virtual Compton scattering from the proton

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    In virtual Compton scattering an electron is scattered off a nucleon such that the nucleon emits a photon. We show that these events can be selected experimentally, and present the first evidence for virtual Compton scattering from the proton in data obtained at the Stanford Linear Accelerator Center. The angular and energy dependence of the data is well described by a calculation that includes the coherent sum of electron and proton radiation

    Multiple roles of mucins in pancreatic cancer, a lethal and challenging malignancy.

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    Mucins are members of an expanding family of large multifunctional glycoproteins. Pancreatic mucins have important biological functions, including the protection, lubrication, and moisturisation of the surfaces of epithelial tissues lining ductal structures within the pancreas. Several lines of evidence support the notion that deregulated mucin production is a hallmark of inflammatory and neoplastic disorders of the pancreas. Herein, we discuss the factors that contribute to the lethality of pancreatic cancer as well as the key role played by mucins, particularly MUC1 and MUC4, in the development and progression of the disease. Aspects pertaining to the aberrant expression and glycosylation of mucins are discussed, with special emphasis on their potential impact on the design and implementation of adequate diagnostic and therapeutic strategies for combating this lethal malignancy

    Real-Time Synthesis is Hard!

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    We study the reactive synthesis problem (RS) for specifications given in Metric Interval Temporal Logic (MITL). RS is known to be undecidable in a very general setting, but on infinite words only; and only the very restrictive BRRS subcase is known to be decidable (see D'Souza et al. and Bouyer et al.). In this paper, we precise the decidability border of MITL synthesis. We show RS is undecidable on finite words too, and present a landscape of restrictions (both on the logic and on the possible controllers) that are still undecidable. On the positive side, we revisit BRRS and introduce an efficient on-the-fly algorithm to solve it
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