3,765 research outputs found

    Chemical freezeout in relativistic A+A collisions: is it close to the QGP?

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    Preliminary experimental data for particle number ratios in the collisions of Au+Au at the BNL AGS (11A GeV/c) and Pb+Pb at the CERN SPS (160A GeV/c) are analyzed in a thermodynamically consistent hadron gas model with excluded volume. Large values of temperature, T = 140 185 MeV, and baryonic chemical potential, µb = 590 270 MeV, close to the boundary of the quark-gluon plasma phase are found from fitting the data. This seems to indicate that the energy density at the chemical freezeout is tremendous which would be indeed the case for the point-like hadrons. However, a self-consistent treatment of the van der Waals excluded volume reveals much smaller energy densities which are very far below a lowest limit estimate of the quark-gluon plasma energy density. PACS number(s): 25.75.-q, 24.10.P

    Laboratory Course Modular Design for Learning Magnetic Components in Power Conversion Applications at Taipei Tech

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    The main theme of this paper is to present the laboratory course modular design for learning and hands-on magnetic components in power converters. The objective of the course is to give the students to model the converters, realize magnetic components and test the implemented converters via the hands-on work in order to improve practical skills of students under the insufficiency of regular course training. This designed course is based upon the modular concept of five modules in common use which include forward converter, flyback converter, push-pull converter, half-bridge converter and full-bridge converter. The controllers for these converter modules include voltage mode control and peak current mode control. The specifications for each converter module are the same, 48V/12V, 60W and 100 kHz of switching frequency. The designed modular curriculum has been applied to the Industrial Technology Research and Development Master (ITRDM) Program sponsored by the industry and government. And excellent acknowledgment from students is received for providing practical training and covering the wide range of magnetic components in power conversion applications

    The impact of institutional quality on ipos oversubscription: evidence in Malaysia

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    The major purpose of this study is to examine the impact of institutional quality on oversubscription of initial public offerings (IPOs) listed in Bursa Malaysia from period of 2000 to 2016. This study exists of six controls variable for controlling the institutional quality on oversubscription. Numerous studies have examined the relationship between institutional quality and oversubscription on IPOs underpricing. This study fills the gap to determine the institutional quality on oversubscription as previous studies prove the oversubscription is significant to underpricing. The six dimension of institutional quality collected from World Governance Indicators (WGI) which consists of voice and accountability, government effectiveness, political stability and absence of violence/terrorism, regulatory quality, rule of law, and control of corruption. The information asymmetry and signaling theory are employed to illustrate the relationship of institutional quality to oversubscription. This study employs cross-sectional multiple regression analysis to test for its entire hypothesis. Analyzing the data of 392 IPOs in Malaysia, the result reveals that voice and accountability, and control of corruption are positive significant to oversubscription while regulatory quality is negative significant on oversubscription. However, government effectiveness, political stability and rule of law show insignificant to oversubscription. The GDP growth rate, firm size and IPOs offer price significant influence the oversubscription. This study could contribute to benefit investors when making investment decision. The results may alert the regulators to implement the sound policies to enhance the IPO market. Future research could examine the institutional quality on oversubscription involve in Asian region, developing and developed countries instead focus in Malaysia

    Glutamate 83 and arginine 85 of helix H3 bend are key residues for FtsZ polymerization, GTPase activity and cellular viability of Escherichia coli: lateral mutations affect FtsZ polymerization and E. coli viability

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    BACKGROUND: FtsZ is an essential cell division protein, which localizes at the middle of the bacterial cell to mediate cytokinesis. In vitro, FtsZ polymerizes and induces GTPase activity through longitudinal interactions to form the protofilaments, whilst lateral interactions result within formation of bundles. The interactions that participate in the protofilaments are similar to its eukaryotic homologue tubulin and are well characterized; however, lateral interactions between the inter protofilaments are less defined. FtsZ forms double protofilaments in vitro, though the key elements on the interface of the inter-protofilaments remain unclear as well as the structures involved in the lateral interactions in vivo and in vitro. In this study, we demonstrate that the highly conserved negative charge of glutamate 83 and the positive charge of arginine 85 located in the helix H3 bend of FtsZ are required for in vitro FtsZ lateral and longitudinal interactions, respectively and for in vivo cell division. RESULTS: The effect of mutation on the widely conserved glutamate-83 and arginine-85 residues located in the helix H3 (present in most of the tubulin family) was evaluated by in vitro and in situ experiments. The morphology of the cells expressing Escherichia coli FtsZ (E83Q) mutant at 42°C formed filamented cells while those expressing FtsZ(R85Q) formed shorter filamented cells. In situ immunofluorescence experiments showed that the FtsZ(E83Q) mutant formed rings within the filamented cells whereas those formed by the FtsZ(R85Q) mutant were less defined. The expression of the mutant proteins diminished cell viability as follows: wild type > E83Q > R85Q. In vitro, both, R85Q and E83Q reduced the rate of FtsZ polymerization (WT > E83Q >> R85Q) and GTPase activity (WT > E83Q >> R85Q). R85Q protein polymerized into shorter filaments compared to WT and E83Q, with a GTPase lag period that was inversely proportional to the protein concentration. In the presence of ZipA, R85Q GTPase activity increased two fold, but no bundles were formed suggesting that lateral interactions were affected. CONCLUSIONS: We found that glutamate 83 and arginine 85 located in the bend of helix H3 at the lateral face are required for the protofilament lateral interaction and also affects the inter-protofilament lateral interactions that ultimately play a role in the functional localization of the FtsZ ring at the cell division site

    Effect of steam jet cooking on the destruction of corn starches

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    AbstractSteam jet cooking has been used for years to prepare aqueous starch dispersions for food application. The steam jet cooking generates high shear stress to starch. The objective of this research is to study the effect of shear stress on structure of corn starch granules by steam jet cooking. A laboratory scale steam jet cooker has been established with flow rate about 1L/min. Three kinds of corn starch, waxy, regular, and high amylose were used. Starch slurries (5% w/w) were cooked by steam jet cooker at temperature 100°C (SJ100), 120°C (SJ120) and 135°C (SJ135) compared with hot water boiling at 90°C 30min (HB). The insoluble particles of cooked starches were investigated by particle size analyzer, scanning electron microscope (SEM) and damage starch assay kit. There was a significant decrease in percent yield of insoluble particles of cooked dispersions for all starches in the order HB > SJ100 > SJ120 > SJ 135.The data also showed that SJ100 has higher destruction than HB, although the temperature of heat treatment was similar. The particle size of cooked starches was much larger than uncooked starches, and the particle size of HB was larger than SJ100 for all starches. This may be due to the time of cooking, 30min for HB vs. a few sec for SJ100. Percentage damaged starch of cooked dispersions for all starches became higher with increasing of cooking temperature. Although, the time of heat treatment was much shorter for SJ100 than HB, the damaged starch was higher as well. Those date all revealed the effect of shear stress from steam cooking. On SEM observation, the damaged granules showed sponge like structure for the starch dispersions cooked by HB. The starches heated by steam jet cooking were fractured into small fragments

    Global and Seasonal Scintillation Morphology in the Equatorial Region Derived from ROCSAT-1 In-situ Data

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    The global/seasonal distributions of the scintillation occurrence rate are obtained from the in-situ density measurement of the ROCSAT-1 using a modified procedure reported by Wernik et al. (2007). A least-squares curve fitting in the optimal trust region is used to obtain the spectral slope for the density irregularity structure and the outer scale of the scintillation. The distribution of the S4 index for the weak scintillation (S4 < 0.3) is almost identical to that of the equatorial irregularity distribution reported in the literature. However, as the scintillation becomes stronger (0.3 < S4 < 0.6), the latitudinal distribution moves to the equatorial ionization anomaly (EIA) region. In addition, the distributions of the outer scale values that are useful for the study of the physical evolution of the irregularity structure are also obtained. The occurrence distribution of scintillation activity with several parameters such as dip-latitude, longitude, local time, solar activity, and geomagnetic activity during different seasons are presented and discussed in this paper

    Boosting Factual Consistency and High Coverage in Unsupervised Abstractive Summarization

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    Abstractive summarization has gained attention because of the positive performance of large-scale, pretrained language models. However, models may generate a summary that contains information different from the original document. This phenomenon is particularly critical under the abstractive methods and is known as factual inconsistency. This study proposes an unsupervised abstractive method for improving factual consistency and coverage by adopting reinforcement learning. The proposed framework includes (1) a novel design to maintain factual consistency with an automatic question-answering process between the generated summary and original document, and (2) a novel method of ranking keywords based on word dependency, where keywords are used to examine the coverage of the key information preserved in the summary. The experimental results show that the proposed method outperforms the reinforcement learning baseline on both the evaluations for factual consistency and coverage

    Stochastic approach to the molecular counting problem in superresolution microscopy.

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    Superresolution imaging methods--now widely used to characterize biological structures below the diffraction limit--are poised to reveal in quantitative detail the stoichiometry of protein complexes in living cells. In practice, the photophysical properties of the fluorophores used as tags in superresolution methods have posed a severe theoretical challenge toward achieving this goal. Here we develop a stochastic approach to enumerate fluorophores in a diffraction-limited area measured by superresolution microscopy. The method is a generalization of aggregated Markov methods developed in the ion channel literature for studying gating dynamics. We show that the method accurately and precisely enumerates fluorophores in simulated data while simultaneously determining the kinetic rates that govern the stochastic photophysics of the fluorophores to improve the prediction's accuracy. This stochastic method overcomes several critical limitations of temporal thresholding methods
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