881 research outputs found

    The Consequences of Information Revealed in Auctions

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    This paper considers the ramifications of post-auction competition on bidding behavior under different bid announcement policies. In equilibrium, the auctioneer’s announcement policy has two distinct effects. First, announcement entices players to signal information to their post-auction competitors through their bids. Second, announcement can lead to greater bidder participation in certain instances while limiting participation in others. Specifically, the participation effect works against the signalling effect, thus reducing the impact of signalling found in other papers. Revenue, efficiency, and surplus implications of various announcement policies are examined

    The Schottky-Klein prime function: a theoretical and computational tool for applications

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    This article surveys the important role, in a variety of applied mathematical contexts, played by the so-called Schottky–Klein (S–K) prime function. While it is a classical special function, introduced by 19th century investigators, its theoretical significance for applications has only been realized in the last decade or so, especially with respect to solving problems defined in multiply connected, or ‘holey’, domains. It is shown here that, in terms of it, many well-known results pertaining only to the simply connected case (no holes) can be generalized, in a natural way, to the multiply connected case, thereby contextualizing those well-known results within a more general framework of much broader applicability. Given the wide-ranging usefulness of the S–K prime function it is important to be able to compute it efficiently. Here we introduce both a new theoretical formulation for its computation, as well as two distinct numerical methods to implement the construction. The combination of these theoretical and computational developments renders the S–K prime function a powerful new tool in applied mathematics

    Polarization of the endomembrane system is an early event in fucoid zygote development

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    BACKGROUND: Fucoid zygotes are excellent experimental organisms for investigating mechanisms that establish cell polarity and determine the site of tip growth. A common feature of polarity establishment is targeting endocytosis and exocytosis (secretion) to localized cortical domains. We have investigated the spatiotemporal development of endomembrane asymmetry in photopolarizing zygotes, and examined the underlying cellular physiology. RESULTS: The vital dye FM4-64 was used to visualize endomembranes. The endomembrane system preferentially accumulated at the rhizoid (growth) pole within 4 h of fertilization. The polarized endomembrane array was initially labile and reoriented when the developmental axis changed direction in response to changing light cues. Pharmacological studies indicated that vesicle trafficking, actin and microtubules were needed to maintain endomembrane polarity. In addition, endocytosis required a functional cortical actin cytoskeleton. CONCLUSION: Endomembrane polarization is an early event in polarity establishment, beginning very soon after photolocalization of cortical actin to the presumptive rhizoid site. Targeting of endocytosis and secretion to the rhizoid cortex contributes to membrane asymmetry. We suggest that microtubule-actin interactions, possibly involving microtubule capture and stabilization at actin-rich sites in the rhizoid, may organize the endomembrane array

    The compact green’s function for multiple bodies

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    Increasing Aging Content within the Social Work Curriculum: Perceptions of Key Constituents

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    This mixed methodology study examines the perceptions of key constituents regarding methods for effectively integrating aging content into the foundation curriculum of the BSW and MSW program at the University of Georgia School of Social Work. Students were asked to complete a survey to determine their perception of geriatric content that existed within the foundation coursework. Following an analysis of the survey results, eight semi-structured focus group discussions were conducted with a purposeful sample of students, faculty, field instructors, social work alumni, older adults from the community, and representatives from aging agencies. The intention of these focus groups was to find out what aging content should be infused within the curriculum. The focus group meetings were held in various locations throughout Northeast Georgia and in one remote location in South Georgia. Participants were interviewed about the necessary skills and knowledge for social workers practicing with an aging population in the areas of: essential intervention skills, program policies and regulations, critical information needed to develop client service plans, strategies for addressing service delivery fragmentation, and community collaboration to support intergenerational family needs. The results of this study will be discussed to provide suggestions on how existing foundation courses can integrate aging content

    Following successful anti-leishmanial treatment, neutrophil counts, CD10 expression and phagocytic capacity remain reduced in visceral leishmaniasis patients co-infected with HIV

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    Visceral leishmaniasis (VL) patients co-infected with HIV (VL/HIV patients) experience frequent treatment failures, VL relapses, opportunistic infections, and higher mortality. Their immune system remains profoundly suppressed after clinical cure and they maintain higher parasite load. This is in contrast with patients with VL alone (VL patients). Since neutrophils play a critical role in the control of Leishmania replication and the regulation of immune responses, we tested the hypothesis that neutrophil activation status and effector functions are fully restored in VL, but not in VL/HIV patients. Our results show the neutrophil counts and all activation markers and effector functions tested in our study were reduced at the time of diagnosis in VL and VL/HIV patients as compared to controls. CD62L, CD63, arginase 1 expression levels and reactive oxygen species production were restored at the end of treatment in both groups. However, neutrophil counts, CD10 expression and phagocytosis remained significantly lower throughout follow-up in VL/HIV patients; suggesting that dysregulated neutrophils contribute to the impaired host defence against pathogens in VL/HIV patients

    Visceral leishmaniasis patients display altered composition and maturity of neutrophils as well as impaired neutrophil effector functions

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    Immunologically, active visceral leishmaniasis (VL) is characterised by profound immunosuppression, severe systemic inflammatory responses and an impaired capacity to control parasite replication. Neutrophils are highly versatile cells, which play a crucial role in the induction as well as the resolution of inflammation, the control of pathogen replication and the regulation of immune responses. Neutrophil functions have been investigated in human cutaneous leishmaniasis, however, their role in human visceral leishmaniasis is poorly understood. In the present study we evaluated the activation status and effector functions of neutrophils in patients with active VL and after successful anti-leishmanial treatment. Our results show that neutrophils are highly activated and have degranulated; high levels of arginase, myeloperoxidase and elastase, all contained in neutrophils’ granules, were found in the plasma of VL patients. In addition, we show that a large proportion of these cells are immature. We also analysed effector functions of neutrophils that are essential for pathogen clearance and show that neutrophils have an impaired capacity to release neutrophil extracellular traps, produce reactive oxygen species and phagocytose bacterial particles, but not Leishmania parasites. Our results suggest that impaired effector functions, increased activation and immaturity of neutrophils play a key role in the pathogenesis of VL

    Effects of tallow and ground flaxseed on sensory and color characteristics of ribeye steaks

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    Forty-eight ribeye steaks from steers fed diets containing steam-flaked corn (SFC), steam-flaked corn with tallow (SFC/Tallow), or steam-flaked corn with rolled flaxseed (Flax) were used to evaluate the effects of dietary fat on sensory traits, retail display color stability, and fatty acid composition. Steaks from Flax-fed steers had increased deposition of alpha linolenic acid (C18:3n3, an omega-3 fatty acid; P<0.01) and developed a detectable off-flavor (P<0.05) when compared to those of cattle fed SFC and SFC/Tallow. There were no differences in tenderness, juiciness, or flavor intensity (P>0.10) among the three treatments. Steaks from cattle fed SFC retained a desirable color longer than those from cattle fed Flax (P<0.05) which may be attributable to premature lipid oxidation in steaks from cattle fed Flax. This study suggests that altering the fat in the diet may affect flavor and color stability of the meat. Feeding flaxseed can effectively alter composition of carcass tissues to yield beef that is high in omega-3 fatty acids, which may lead to premature lipid oxidation

    Effects of packaging on bone marrow discoloration in beef arm, rib, shoulder blade, and thoracic vertebra bones

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    Meat retailers have reported bone marrow discoloration to be a problem, especially in modified-atmosphere packages (MAP). To evaluate causes of bone marrow discoloration in different beef bones and packaging systems, 36 beef arm bones, ribs, shoulder blades, and thoracic vertebrae from USDA Select and Choice carcasses were obtained from a commercial abattoir, cut into 1-inch-thick sections at 4 days postmortem, and packaged into 1) polyvinyl chloride film (PVC) overwrap; 2) high-oxygen (80% O2, 20% CO2) MAP; or 3) ultra-low-oxygen (70% N2, 30% CO2) MAP. Packages were displayed under continuous fluorescent lighting for 4 days at 35.6°F. Ribs, shoulder blades, and thoracic vertebrae packaged in PVC and high-oxygen MAP developed undesirable gray or black discoloration during display. In ultra-low-oxygen MAP, mean visual-color scores were acceptable throughout display. The a* values (larger values equate to redder color) for ribs, shoulder blades, and thoracic vertebrae decreased (P<0.05) over time. Arm-bone marrow had less oxidation and dramatically less total iron and hemoglobin than did marrow from ribs and thoracic vertebrae. The much larger amounts of iron and hemoglobin in ribs and thoracic vertebrae likely correspond to marrow discoloration. In summary, bone marrow discoloration occurs in ribs, shoulder blades, and thoracic vertebrae packaged in PVC or high-oxygen MAP. Bones packaged in ultralow- oxygen MAP or arm bones packaged in PVC or high-oxygen MAP had minimal oxidation and discoloration

    ANANALYTICAL STUDY OF MARBLE CONSOLIDATION BY OXALATE PRECIPITATION USING DENSITY, FTIR AND POWDER-XRD MEASUREMENTS

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    oai:ojs2.www.jepm.rs.ba:article/28Our recent study on consolidation of marble samples with the purpose of culture heritage protection occurred by periodical calcium oxalate precipitation on top of quasi parallelepipedic samples. The overall process consisting of three stages of treatment, starting with 5 % calcium acetate solution for 60 minutes at 20°C, a draining step at 70°C for 30 min, followed by a treatment with 5 % ammonium sulfate solution, it followed with the third stage which includes the treatment with 5% ammonium oxalate solution revealed a continuous density increace, determined using ethanol. As the natural samples had an initial density of 2.5871 g/cm3 , it increased up to 2.6980 g/cm3 for 50 times treatments. The precipitation of oxalate on top of calcium carbonate substrate, in form of calcite, revealed two distinguished infra-red bands, at 1316 cm-1 and 1624 cm-1 unsymmetrically located around the carbonate one at 1426 cm-1 .The intensity of the bands was proportional to the number of treatments. The continuous surface coverage investigated in parallel by powder XRD evidenced the presence of whewellite crystallites deposited on top of calcite, and their intensity increasing as well with the number of treatments. This method exhibits a reliable oxalate coverage of marble sample surfaces which doesn’t influence considerably their water solubility
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