434 research outputs found

    A Study of the Thermodynamical Properties of a Hot, Dense Hadron Gas Using an Event Generator - Hadro-Molecular-Dynamical Calculation -

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    We investigate the equilibration and the equation of state of a hot hadron gas at finite baryon density using an event generator which is designed to approximately satisfy detailed balance at finite temperatures and finite baryon densities of the hadronic scale (80 MeV < T < 170 MeV and 0.157 fm^-3 < n_B < 0.315 fm^-3). Molecular-dynamical simulations were performed for a system of hadrons in a box with periodic boundary conditions. Starting from an initial state composed of only nucleons with a uniform phase-space distribution, the evolution takes place through interactions such as collisions, productions and absorptions. The system approaches a stationary state of baryons, mesons and their resonances, which is characterized by the value of the exponent in the energy distribution common to the different particles, i.e., the temperature. After the equilibration, thermodynamic quantities, such as the energy density, particle density, entropy and pressure are calculated. Above T - m_pi, the obtained equation of state exhibits a significant deviation from the naive mixed free gas model. Large values of the entropy per baryon are also notable. In our system, the excitation of heavy baryon resonances and meson production are enhanced simultaneously, and the increase of the temperature becomes moderate, but a Hagedorn-type artificial temperature saturation does not occur. The pressure exhibits a linear dependence on the energy density.Comment: 23 pages, 20 figure

    A Calculation of the Viscosity to Entropy Ratio of a Hadronic Gas

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    We calculate thermodynamic quantities and transport coefficients of a hadronic gas using a Monte Carlo hadronic collision event generator URASiMA. The obtained shear viscosity to entropy density ratio of the hadronic gas is approximately 0.3 -- 0.6 in the range TT = 100 -- 180MeV and is quite insensitive to the baryon number density.Comment: 7 pages, 6 figure

    "Action Timing as a Collusive Common Good"

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    Frequent revision of firms' actions facilitates to sustain tacit collusion. Even when some, not all, firms revise their actions with enhanced frequency, the change contributes positively to collusive sustainability, i.e., lowering the critical discount factor. In this sense, the added frequency in revising actions can be viewed as a common good shared among oligopolists. Particularly noteworthy is the fact that, in a large class of environments, a firm's deviation can be deterred by no more than one punisher, implying that at most two firms need to invest in frequent revision in order to sustain collusion.

    "Inflexibility as a Stabilisation Device"

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    A possible rationale for institutional conservatism, i.e., reluctance to adjust actions in accordance with external environmental changes, may be found in the payoff stabilisation effect it strategically affords. Suppose, for example, that one of the duopolists is capable of adjusting its action, either price or quantity, in response to unexpected demand fluctuations. Then the other duopolist, if incapable of such adjustments, recuperates some of the meager opportunities when the shock is negative whilst forgoing lucrative profit opportunities when the demand shock is positive, thereby "smoothes" its profits across varying states of demand in exchange for a small loss in expected profits, as opposed to when being as adjustable as its competitor. Similar qualitative results hold true both in Cournot and in Bertrand, and by extension, in a larger class of situations where economic decision makers interact through either strategic substitution or strategic complementarity.

    Development and Strategy for A-USC Steam Turbine Cycle

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    ABSTRACT Efficiency improvement of thermal power plants is one of the key technologies to protect the global environment because of lower emission gas. There are many approaches in this regard, which are investigated and developed around the world. Thermal efficiency of fossil power plants has been improved by raising steam temperature as high as 620 C in a realization of Ultra Super Critical (USC) steam turbine system. In order to enhance the thermal efficiency further, we are developing the Advanced Ultra Super Critical (A-USC) steam turbine system using high pressure and high temperature steam of 700 C or over 700 C. The main focus of the Research &amp; Development of A-USC steam turbine is the verification of the alloys for the large rotor, casing and valve components, and the main issue for application to the power plant is an economical aspect and field of technology for the realization of such steam conditions with cost-effectiveness, for instance, optimization of cycle heat balance, turbine design, welding technology and so on. This paper describes briefly about R&amp;D results of A-USC steam turbine and suggests an economical strategy in order to make it possible to be realized sooner

    Risk of transmission of viral haemorrhagic fevers and the insecticide susceptibility status of aedes aegypti (linnaeus) in some sites in Accra, Ghana

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    Background: Dengue is one of the emerging diseases that can mostly only be controlled by vector control since there is no vaccine for the disease. Although, Dengue has not been reported in Ghana, movement of people from neighbouring countries where the disease has been reported can facilitate transmission of the disease. Objective: This study was carried on the University of Ghana campus to determine the risk of transmission of viral haemorrhagic fevers and the insecticide susceptibility status of Ae. aegypti in some sites in Accra, Ghana. Design: Larval surveys were carried to inspect containers within households and estimate larval indices and adult Aedes mosquitoes were collected using human landing collection technique. WHO tube assays was used to assess the insecticide susceptibility status of Aedes mosquitoes. Results: Ae. aegypti were the most prevalent species, 75.5% and followed by Ae. vittatus, 23.9 %. Ae. albopictus and Ae. granti were in smaller numbers. Household index (HI), Breteau index (BI), and container index were calculated as 8.2%, 11.2% and 10.3% respectively with man-vector contact rate of 0.67 bites/man-hour estimated for the area. The mortalities recorded for Ae. aegypti from WHO tube assays was 88%, 94%, 80% and 99% for DDT (4%), deltamethrin (0.05%), lambdacyhalothrin (0.05%) and permethrin (0.75%) respectively.Conclusion: The survey results indicated that the density of Aedes mosquitoes was considered to be sufficient to promote an outbreak of viral haemorrhagic fevers on Legon Campus. Aedes mosquitoes were found to be resistant to DDT, deltamethrin and lamdacyhalothrin, but susceptible to permethrin. Funding: This study was supported in part by Japan Initiative for Global Research Network on Infectious Diseases(J-Grid).Keywords: Mosquitoes, Aedes aegypti, insecticide, risk, VHF transmission, Ghan

    Evaluation of automated measurement of left ventricular volume by novel real-time 3-dimensional echocardiographic system: Validation with cardiac magnetic resonance imaging and 2-dimensional echocardiography

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    AbstractBackgroundTraditional 3-dimensional echocardiography (3DE) with volumetric scanning technique requires several heart cycles for full-volume acquisition and complicated manual contouring of left ventricular (LV) endocardium. The new real-time 3DE (RT3DE) system allows acquisition of an instantaneous full-volume dataset in a single heart cycle and automated measurement of LV volume by the algorithm software. However, it has not been evaluated adequately whether automated measurement by RT3DE has better agreement with cardiac magnetic resonance imaging (CMR) than 2-dimensional echocardiography (2DE) with CMR.PurposeThis study aimed to evaluate the accuracy of automated measurement of LV volume using RT3DE compared with 2DE and CMR.Methods and resultsForty-four consecutive patients who underwent RT3DE, 2DE, and CMR were evaluated in this study. The feasibility of automated measurement by RT3DE was 93.2% and the mean operation time was 6min. LV volume and ejection fraction (EF) from semi-automated measurement [end-diastolic volume: r=0.96, limits of agreement (LOA) −30.5 to 39.3ml; end-systolic volume: r=0.97, LOA −22.6 to 32.7ml; EF: r=0.90, LOA −16.1 to 14.2%, respectively] had better agreement with CMR than those from 2DE (r=0.87, LOA −50.5 to 72.2ml; r=0.93, LOA −34.1 to 65.2ml; r=0.89, LOA −20.9 to 10.0%, respectively).ConclusionSemi-automated measurement by RT3DE has better agreement with CMR than 2DE in LV volume and EF. In addition, it is simple to operate and acceptable in feasibility for the clinical setting although there may be room for further learning required to incorporate small hypertrophic LV into the automated algorithm software

    Downstream genes of Pax6 revealed by comprehensive transcriptome profiling in the developing rat hindbrain

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    Abstract Background The transcription factor Pax6 is essential for the development of the central nervous system and it exerts its multiple functions by regulating the expression of downstream target molecules. To screen for genes downstream of Pax6, we performed comprehensive transcriptome profiling analyses in the early hindbrain of Pax6 homozygous mutant and wild-type rats using microarrays. Results Comparison of quadruplicate microarray experiments using two computational methods allowed us to identify differentially expressed genes that have relatively small fold changes or low expression levels. Gene ontology analyses of the differentially expressed molecules demonstrated that Pax6 is involved in various signal transduction pathways where it regulates the expression of many receptors, signaling molecules, transporters and transcription factors. The up- or down-regulation of these genes was further confirmed by quantitative RT-PCR. In situ staining of Fabp7, Dbx1, Unc5h1 and Cyp26b1 mRNAs showed that expression of these transcripts not only overlapped with that of Pax6 in the hindbrain of wild-type and Pax6 heterozygous mutants, but also was clearly reduced in the hindbrain of the Pax6 homozygous mutant. In addition, the Pax6 homozygous mutant hindbrain showed that Cyp26b1 expression was lacked in the dorsal and ventrolateral regions of rhombomeres 5 and 6, and that the size of rhombomere 5 expanded rostrocaudally. Conclusions These results indicate that Unc5h1 and Cyp26b1 are novel candidates for target genes transactivated by Pax6. Furthermore, our results suggest the interesting possibility that Pax6 regulates anterior-posterior patterning of the hindbrain via activation of Cyp26b1, an enzyme that metabolizes retinoic acid

    IL-18 with IL-2 protects against Strongyloides venezuelensis infection by activating mucosal mast cell–dependent type 2 innate immunity

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    C57BL/6 (B6) and B6 background STAT6−/− mice pretreated with IL-18 plus IL-2 showed prominent intestinal mastocytosis and rapidly expelled implanted adult worms of the gastrointestinal nematode Strongyloides venezuelensis. In contrast, identically pretreated mast cell–deficient W/Wv mice failed to do so. Thus, activated mucosal mast cells (MMC) are crucial for parasite expulsion. B6 mice infected with S. venezuelensis third-stage larvae (L3) completed parasite expulsion by day 12 after infection, whereas IL-18−/− or IL-18Rα−/− B6 mice exhibited marked impairment in parasite expulsion, suggesting a substantial contribution of IL-18–dependent MMC activation to parasite expulsion. Compared with IL-18−/− or IL-18Rα−/− mice, S. venezuelensis L3–infected STAT6−/− mice have poorly activated MMC and sustained infection; although their IL-18 production is normal. Neutralization of IL-18 and IL-2 further reduces expulsion in infected STAT6−/− mice. These results suggest that collaboration between IL-18–dependent and Th2 cell–dependent mastocytosis is important for prompt parasite expulsion
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