782 research outputs found

    Idiosyncratic Consumption Risk and the Cross-Section of Asset Returns

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    This paper investigates the importance of idiosyncratic consumption risk for the cross-sectional variation in average returns on stocks and bonds. If idiosyncratic consumption risk is not priced, the only pricing factor in a multiperiod economy is the rate of aggregate consumption growth. We offer evidence that the cross-sectional variance of consumption growth is also a priced factor. This demonstrates that consumers are not fully insured against idiosyncratic consumption risk, and that asset returns reflect their attempts to reduce their exposure to this risk. We find that over the sample period the resulting two-factor consumption-based asset pricing model significantly outperforms the CAPM. The model's empirical performance also compares favorably with that of the Fama-French three-factor model. Moreover, in the presence of the market factor and the size and book-to-market factors, the two consumption based factors retain explanatory power. Together with the results of Lettau and Ludvigson (2000), these findings indicate that consumption-based asset pricing is relevant for explaining the cross-section of asset returns. Cet article analyse l'importance du risque idiosyncratique de la consommation individuelle pour la variance transversale des rendements moyens des actifs et des obligations. Lorsque l'on n'attribue pas de prix au risque idiosyncratique de la consommation individuelle, le seul facteur d'évaluation dans une économie à plusieurs horizons est le taux de croissance de la consommation agrégée. Nous montrons que la variance transversale de la croissance de la consommation est également un facteur dont le prix est déterminé. Ceci démontre que les consommateurs ne sont pas complètement assurés contre le risque idiosyncratique de la consommation et que les rendements des actifs reflètent leurs efforts à réduire leur exposition à ce risque. Pour la période considérée, nous trouvons que le modèle d'évaluation d'actifs à deux facteurs basés sur la consommation donne de meilleurs résultats que le CAPM. De plus, la performance empirique du modèle se compare favorablement avec celle du modèle à trois facteurs de Fama-French. Par ailleurs, en présence du facteur de marché et des facteurs taille et ratio valeur comptable/cours, les deux facteurs basés sur la consommation conservent leur pouvoir explicatif. Combiné aux résultats de Lettau et Ludvigson (2000), ces résultats indiquent que l'évaluation d'actifs à partir de la consommation sert à expliquer l'intégralité des rendements d'actifs.cross-sectional asset pricing; consumption-based model; idiosyncratic consumption risk; incomplete markets; measurement error, évaluation d'actifs transversale, modèle basé sur la consommation, risque de consommation idiosyncratique, marchés incomplets, erreur de mesure

    An integrated optical CO2 sensor. Phase 0: Design and fabrication of critical elements

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    Significant progress has been made toward all of the goals for the first phase of the project short of actual fabrication of a light path. Two alternative approaches to fabricating gold mirrors using the basic LIGA process were developed, one using electroplated solid gold mirrors and the second using gold plated over a nickel base. A new method of fabrication, the transfer mask process, was developed and demonstrated. Analysis of the projected surface roughness and beam divergence effects was completed. With gold surface with low surface roughness scattering losses are expected to be insignificant. Beam divergence due to diffraction will require a modification of the original design, but should be eliminated by fabricating mirrors 1000 mu m in height by 1000 mu m in width and using a source with an initial beam radius greater than 300 mu m. This may eliminate any need for focusing optics. Since the modified design does not affect the mask layout, ordering of the mask and fabrication of the test structures can begin immediately at the start of Phase 1

    Limitations of perturbative techniques in the analysis of rhythms and oscillations

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    Perturbation theory is an important tool in the analysis of oscillators and their response to external stimuli. It is predicated on the assumption that the perturbations in question are “sufficiently weak”, an assumption that is not always valid when perturbative methods are applied. In this paper, we identify a number of concrete dynamical scenarios in which a standard perturbative technique, based on the infinitesimal phase response curve (PRC), is shown to give different predictions than the full model. Shear-induced chaos, i.e., chaotic behavior that results from the amplification of small perturbations by underlying shear, is missed entirely by the PRC. We show also that the presence of “sticky” phase–space structures tend to cause perturbative techniques to overestimate the frequencies and regularity of the oscillations. The phenomena we describe can all be observed in a simple 2D neuron model, which we choose for illustration as the PRC is widely used in mathematical neuroscience

    Predatory Bacteria: A Potential Ally against Multidrug-Resistant Gram-Negative Pathogens

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    Multidrug-resistant (MDR) Gram-negative bacteria have emerged as a serious threat to human and animal health. Bdellovibrio spp. and Micavibrio spp. are Gram-negative bacteria that prey on other Gram-negative bacteria. In this study, the ability of Bdellovibrio bacteriovorus and Micavibrio aeruginosavorus to prey on MDR Gram-negative clinical strains was examined. Although the potential use of predatory bacteria to attack MDR pathogens has been suggested, the data supporting these claims is lacking. By conducting predation experiments we have established that predatory bacteria have the capacity to attack clinical strains of a variety of ß-lactamase-producing, MDR Gram-negative bacteria. Our observations indicate that predatory bacteria maintained their ability to prey on MDR bacteria regardless of their antimicrobial resistance, hence, might be used as therapeutic agents where other antimicrobial drugs fail. © 2013 Kadouri et al

    Determination of Malachite Green in Aquaculture Water by Adsorptive Stripping Voltammetry

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    © 2016, Copyright © Taylor & Francis Group, LLC. An adsorptive stripping voltammetric method for the determination of malachite green in aquaculture water has been developed. Initial studies were made using the cyclic voltammetry of malachite green at a glassy carbon electrode in 0.1M phosphate buffer from pH 2 to 10. The redox behavior observed for malachite green was verified by the characterization of malachite green and its reduction product, leucomalachite green. Furthermore, leucomalachite green was found not to interfere with the determination of malachite green at pH 7.4, the optimum pH for malachite green determination. As a result, further studies were performed using adsorptive stripping voltammetry for the determination of malachite green in aquaculture water. The voltammetric waveform, accumulation potential, and accumulation time were optimized. The calibration plot was linear from 0.2µM to 1.2µM for malachite green using differential pulse voltammetry with a sensitivity of 0.8311µA/µM. Using the method of multiple standard addition, aquaculture water fortified with 0.5µM and 0.75µM malachite green provided mean recoveries of 78.79% and 87.20% with coefficients of variation of 2.07% and 1.45%. Therefore, analytical figures of merit suggest that this method provides rapid, simple, economical, and precise determination of malachite green in aquaculture water

    Development of an Aryloxazole Class of Hepatitis C Virus Inhibitors Targeting the Entry Stage of the Viral Replication Cycle

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    Reliance on hepatitis C virus (HCV) replicon systems and protein-based screening assays has led to treatments that target HCV viral replication proteins. The model does not encompass other viral replication cycle steps such as entry, processing, assembly and secretion, or viral host factors. We previously applied a phenotypic high-throughput screening platform based on an infectious HCV system and discovered an aryloxazole-based anti-HCV hit. Structure– activity relationship studies revealed several compounds exhibiting EC50 values below 100 nM. Lead compounds showed inhibition of the HCV pseudoparticle entry, suggesting a different mode of action from existing HCV drugs. Hit 7a and lead 7ii both showed synergistic effects in combination with existing HCV drugs. In vivo pharmacokinetics studies of 7ii showed high liver distribution and long half-life without obvious hepatotoxicity. The lead compounds are promising as preclinical candidates for the treatment of HCV infection and as molecular probes to study HCV pathogenesis

    Pharmacokinetic evaluation of the PNC disassembler metarrestin in wild-type and Pdx1-Cre;LSL-KrasG12D/+;Tp53R172H/+ (KPC) mice, a genetically engineered model of pancreatic cancer

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    This work is licensed under a Creative Commons Attribution 4.0 International License.Purpose Metarrestin is a first-in-class small molecule clinical candidate capable of disrupting the perinucleolar compartment, a subnuclear structure unique to metastatic cancer cells. This study aims to define the pharmacokinetic (PK) profile of metarrestin and the pharmacokinetic/pharmacodynamic relationship of metarrestin-regulated markers. Methods PK studies included the administration of single or multiple dose of metarrestin at 3, 10, or 25 mg/kg via intravenous (IV) injection, gavage (PO) or with chow to wild-type C57BL/6 mice and KPC mice bearing autochthonous pancreatic tumors. Metarrestin concentrations were analyzed by UPLC–MS/MS. Pharmacodynamic assays included mRNA expression profiling by RNA-seq and qRT-PCR for KPC mice. Results Metarrestin had a moderate plasma clearance of 48 mL/min/kg and a large volume of distribution of 17 L/kg at 3 mg/kg IV in C57BL/6 mice. The oral bioavailability after single-dose (SD) treatment was > 80%. In KPC mice treated with SD 25 mg/kg PO, plasma AUC0–∞ of 14400 ng h/mL, Cmax of 810 ng/mL and half-life (t1/2) of 8.5 h were observed. At 24 h after SD of 25 mg/kg PO, the intratumor concentration of metarrestin was high with a mean value of 6.2 µg/g tissue (or 13 µM), well above the cell-based IC50 of 0.4 µM. At multiple dose (MD) 25 mg/kg/day PO in KPC mice, mean tissue/plasma AUC0–24h ratio for tumor, spleen and liver was 37, 30 and 31, respectively. There was a good linear relationship of dosage to AUC0–24h and C24h. AUC0–24h MD to AUC0–24h SD ratios ranged from two for liver to five for tumor indicating additional accumulation in tumors. Dose-dependent normalization of FOXA1 and FOXO6 mRNA expression was observed in KPC tumors. Conclusions Metarrestin is an effective therapeutic candidate with a favorable PK profile achieving excellent intratumor tissue levels in a disease with known poor drug delivery.Intramural Research Program (IRP) of the NIHNational Cancer InstituteCenter for Cancer Research (ZIA BC 011267

    No Detectable Fertility Benefit from a Single Additional Mating in Wild Stalk-Eyed Flies

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    Background: Multiple mating by female insects is widespread, and the explanation(s) for repeated mating by females has been the subject of much discussion. Females may profit from mating multiply through direct material benefits that increase their own reproductive output, or indirect genetic benefits that increase offspring fitness. One particular direct benefit that has attracted significant attention is that of fertility assurance, as females often need to mate multiply to achieve high fertility. This hypothesis has never been tested in a wild insect population.Methodology/Principal Findings: Female Malaysian stalk-eyed flies (Teleopsis dalmanni) mate repeatedly during their lifetime, and have been shown to be sperm limited under both laboratory and field conditions. Here we ask whether receiving an additional mating alleviates sperm limitation in wild females. In our experiment one group of females received a single additional mating, while a control group received an interrupted, and therefore unsuccessful, mating. Females that received an additional mating did not lay more fertilised eggs in total, nor did they lay proportionately more fertilised eggs. Female fertility declined significantly through time, demonstrating that females were sperm limited. However, receipt of an additional mating did not significantly alter the rate of this decline.Conclusions/Significance: Our data suggest that the fertility consequences of a single additional mating were small. We discuss this effect (or lack thereof), and suggest that it is likely to be attributed to small ejaculate size, a high proportion of failed copulations, and the presence of X-linked meiotic drive in this species
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