1,180 research outputs found

    Dilaton-Limit Fixed Point in Hidden Local Symmetric Parity Doublet Model

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    We study nucleon structure with positive and negative parities using a parity doublet model endowed with hidden local symmetry (HLS) with the objective to probe dense baryonic matter. The model -- that we shall refer to as "PDHLS model" for short -- allows a chiral-invariant mass of the nucleons unconnected to spontaneously broken chiral symmetry which comes out to be m_0 ~ 200 MeV at tree level from fitting to the decay width of the parity doubler, N(1535), to nucleon-pion and nucleon axial coupling g_A=1.267. The presence of a substantial m_0 that remains non-vanishing at chiral restoration presents a deep issue for the origin of the nucleon mass as well as will affect nontrivially the equation of state for dense baryonic matter relevant for compact stars. We construct a chiral perturbation theory at one-loop order and explore the phase structure of the model using renormalization group equations. We find a fixed point that corresponds exactly to the "dilaton limit" at which the HLS vector mesons decouple from the nucleons before reaching the vector manifestation fixed point. We suggest that cold baryonic system will flow to this limit as density increases toward that of chiral restoration.Comment: 22 pages, 6 figure

    Conformal anomaly and the vector coupling in dense matter

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    We construct an effective chiral Lagrangian for hadrons implemented by the conformal invariance and discuss the properties of nuclear matter at high density. The model is formulated based on two alternative assignment, "naive" and mirror, of chirality to the nucleons. It is shown that taking the dilaton limit, in which the mended symmetry of Weinberg is manifest, the vector-meson Yukawa coupling becomes suppressed and the symmetry energy becomes softer as one approaches the chiral phase transition. This leads to softer equations of state (EoS) and could accommodate the EoS without any exotica consistent with the recent measurement of a 1.97±0.04M1.97 \pm 0.04\,M_\odot neutron star.Comment: v2:10 pages, 2 figures, typos corrected, a rough estimate of m0 adde

    Portal flow steal after liver transplantation

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    Portal flow steal occasionally persists even after the liver transplantation, which may reduce the portal flow and thus threaten the patients' outcome. Therefore, pre- and peri-operative detection of portal steal phenomenon requiring radiological or surgical interruption is essential for the liver transplantation candidates as well as for the recipients

    An OFDMA-Based Next-Generation Wireless Downlink System Design with Hybrid Multiple Access and Frequency Grouping Techniques

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    This paper discusses how to effectively design a nextgeneration wireless communication system that can possibly provide very high data-rate transmissions and versatile quality services. In order to accommodate the sophisticated user requirements and diversified user environments of the next-generation systems, it should be designed to take an efficient and flexible structure for multiple access and resource allocation. In addition, the design should be optimized for cost-effective usage of resources and for efficient operation in a multi-cell environment. As orthogonal frequency division multiple access (OFDMA) has turned out in recent researches to be one of the most promising multiple access techniques that can possibly meet all those requirements through efficient radio spectrum utilization, we take OFDMA as the basic framework in the next-generation wireless communications system design. So, in this paper, we focus on introducing an OFDMA-based downlink system design that employs the techniques of hybrid multiple access (HMA) and frequency group (FG) in conjunction with intra-frequency group averaging (IFGA). The HMA technique combines various multiple access schemes on the basis of OFDMA system, adopting the multiple access scheme that best fits to the given user condition in terms of mobility, service, and environment. The FG concept and IFGA technique help to reduce the feedback overhead of OFDMA system and the other-cell interference (OCI) problem by grouping the sub-carriers based on coherence bandwidths and by harmonizing the channel condition and OCI of the grouped sub-carriers.This work was supported in part by Samsung Advanced Institute of Technology

    Multiplex quantitative analysis of microRNA expression via exponential isothermal amplification and conformation-sensitive DNA separation

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    Expression profiling of multiple microRNAs (miRNAs) generally provides valuable information for understanding various biological processes. Thus, it is necessary to develop a sensitive and accurate miRNA assay suitable for multiplexing. Isothermal exponential amplification reaction (EXPAR) has received significant interest as an miRNA analysis method because of high amplification efficiency. However, EXPAR cannot be used for a broader range of applications owing to limitations such as complexity of probe design and lack of proper detection method for multiplex analysis. Here, we developed a sensitive and accurate multiplex miRNA profiling method using modified isothermal EXPAR combined with high-resolution capillary electrophoresis-based single-strand conformation polymorphism (CE-SSCP). To increase target miRNA specificity, a stem-loop probe was introduced instead of a linear probe in isothermal EXPAR to allow specific amplification of multiple miRNAs with minimal background signals. CE-SSCP, a conformation-dependent separation method, was used for detection. Since CE-SSCP eliminates the need for probes to have different lengths, easier designing of probes with uniform amplification efficiency was possible. Eight small RNAs comprising six miRNAs involved in Caenorhabditis elegans development and two controls were analyzed. The expression patterns obtained using our method were concordant with those reported in previous studies, thereby supporting the proposed method's robustness and utility.113sciescopu

    Growth characteristics and productivity of cold-tolerant “Kowinearly” Italian ryegrass in the northern part of South Korea

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    The objective of this research is to evaluate differences in growth characteristics and productivity between Kowinearly and Florida 80 Italian ryegrass varieties in regions with severely cold winters. This research was carried out in Suwon (in central South Korea) and Yonchun (in northern South Korea) during the 2002 2006 growing seasons. Kowinearly is a diploid variety with green leaf colour and a semi prostrate growth habit in autumn and a semi-erect one in spring. There were differences among the varieties in terms of cold tolerance, heading date, and forage yield in Yonchun. The winter field survival of Kowinearly was 85%, while that of Florida 80 was 43%. The dry matter yield of Kowinearly in Yonchun was 9,662 kg/ha, which was 31% more than that of Florida 80. In Suwon, the heading date of Kowinearly was May 7, which was 2 days later than that of Florida 80. In Yonchun, Kowinearly’s heading date was May 12, 1 day earlier than that of Florida 80. These results indicate that Kowinearly has good cold tolerance, and that in spring, it starts growth earlier than Florida 80, because of its higher cold tolerance.Keywords: Italian ryegrass, Kowinearly, cold tolerance, new variety, forage cro

    Tetraarsenic Hexoxide Induces Beclin-1-Induced Autophagic Cell Death as well as Caspase-Dependent Apoptosis in U937 Human Leukemic Cells

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    Tetraarsenic hexaoxide (As4O6) has been used in Korean folk remedy for the treatment of cancer since the late 1980s, and arsenic trioxide (As2O3) is currently used as a chemotherapeutic agent. However, evidence suggests that As4O6-induced cell death pathway was different from that of As2O3. Besides, the anticancer effects and mechanisms of As4O6 are not fully understood. Therefore, we investigated the anticancer activities of As4O6 on apoptosis and autophagy in U937 human leukemic cells. The growth of U937 cells was inhibited by As4O6 treatment in a dose- and a time-dependent manner, and IC50 for As4O6 was less than 2 μM. As4O6 induced caspase-dependent apoptosis and Beclin-1-induced autophagy, both of which were significantly attenuated by Bcl-2 augmentation and N-acetylcysteine (NAC) treatment. This study suggests that As4O6 should induce Beclin-1-induced autophagic cell death as well as caspase-dependent apoptosis and that it might be a promising agent for the treatment of leukemia
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