2,146 research outputs found

    Electromagnetic form factors of pion and rho in the three forms of relativistic kinematics

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    The electromagnetic form factors of the π\pi and the ρ\rho are obtained using the three forms of relativistic kinematics, instant form, point form and (light) front form. Simple representations of the mass operator together with single quark currents are employed with all the forms. The Poincar\'e covariant current operators are generated by the dynamics from single-quark currents that are covariant under the kinematic subgroup. Front and instant forms allow to reproduce the available data for the pion form factor. On the other hand point form is not able to reproduce qualitatively the experimental data with reasonable values for the wave function parameters. For the ρ\rho electromagnetic form factors, instant and front forms provide a consistent picture. The obtained results do not depend appreciably on the wave function used.Comment: 10 pages, color figures. Revised references and discussion. Accepted in Phys. Letts.

    Electroweak properties of the π\pi, KK and K(892)K^*(892) in the three forms of relativistic kinematics

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    The electromagnetic form factors, charge radii and decay constants of pion, K and K*(892) are calculated using the three forms of relativistic kinematics: instant form, point form and (light) front form. Simple representations of the mass operator together with single quark currents are employed with all the forms. Making use of previously fixed parameters, together with the constituent quark mass for the strange quark, a reasonable reproduction of the available data for form factors, charge radii and decay constants of pion, rho, K and K*(892) is obtained in front form. With instant form a similar description, but with a systematic underestimation of the vector meson decay constants is obtained using two different sets of parameters, one for pion and rho and another one for K and K*(892). Point form produces a poor description of the data.Comment: Accepted in Eur. Phys. Jour. A (2005

    Development of an approximate construction duration prediction model during the project planning phase for general office buildings

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    Accurate prediction of the construction duration is imperative to the reliable cash flow analysis during the project planning phase when feasibility analysis is carried out. However, lack of information and frequent changes that occur as a result of a negotiation process between the owner and the designer in defining the project scope make it difficult to compute real-time construction duration. Domestic and foreign models for calculating the construction durations cannot be readily applied to computation of construction duration for general office buildings in Korea specifically during the project planning phase as there is a limit in its applicability due to numerous restrictions. Moreover, there are no preceding studies suggesting different computational approaches to predict the entire construction duration for office buildings with the approximate construction duration concept during planning phase. Therefore, based on the collected performance data, this study proposes a multiple linear regression model that facilitates reliable prediction of approximate construction duration for office buildings in the project planning phase. The model will allow the owner and other stakeholders to predict the real-time construction duration using the basic information on office buildings and to assess the construction durations incorporating frequent changes during the project planning phase

    Inducible Nucleosome Depletion at OREBP-Binding-Sites by Hypertonic Stress

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    Background: Osmotic Response Element-Binding Protein (OREBP), also known as TonEBP or NFAT5, is a unique transcription factor. It is hitherto the only known mammalian transcription factor that regulates hypertonic stress-induced gene transcription. In addition, unlike other monomeric members of the NFAT family, OREBP exists as a homodimer and it is the only transcription factor known to bind naked DNA targets by complete encirclement in vitro. Nevertheless, how OREBP interacts with target DNA, also known as ORE/TonE, and how it elicits gene transcription in vivo, remains unknown. Methodology: Using hypertonic induction of the aldose reductase (AR) gene activation as a model, we showed that OREs contained dynamic nucleosomes. Hypertonic stress induced a rapid and reversible loss of nucleosome(s) around the OREs. The loss of nucleosome(s) was found to be initiated by an OREBP-independent mechanism, but was significantly potentiated in the presence of OREBP. Furthermore, hypertonic induction of AR gene was associated with an OREBPdependent hyperacetylation of histones that spanned the 59 upstream sequences and at least some exons of the gene. Nevertheless, nucleosome loss was not regulated by the acetylation status of histone. Significance: Our findings offer novel insights into the mechanism of OREBP-dependent transcriptional regulation and provide a basis for understanding how histone eviction and transcription factor recruitment are coupled. © 2009 Tong et al.published_or_final_versio

    Phylogeography of the endangered orchids Cypripedium japonicum and Cypripedium formosanum in East Asia: Deep divergence at infra- and interspecific levels

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    To date, little is known about the past evolutionary trajectories of rare and endangered orchids native to mainland China, Japan, and Korea (the CJK region). In this study, we focus on two endangered orchids, Cypripedium japonicum (present in the three countries) and C. formosanum (endemic to Taiwan), to understand the divergence/speciation models that would have been operating in this group, including genetic diversity, geographic structure, and colonization pathways across the region. Using a combination of five cpDNA regions, we reconstructed phylogenetic trees and investigated the genetic diversity/structure of 20 populations. Ecological niche modeling was used to gain insight into the paleodistribution and dispersal corridors at the Last Glacial Maximum and to survey climatic niche differences. Populations from mainland China + Korea, Japan, and Taiwan formed three distinct monophyletic lineages and were placed into separate genetic clusters, agreeing with geographic barriers and species boundaries. Populations of C. japonicum in mainland China harbored the highest diversity, suggesting the presence of multiple glacial refugia. The Korean populations would have originated from either western/central or eastern China, probably using a dispersal corridor across the East China Sea shelf. The divergence of C. formosanum is proposed under an allopatric speciation model, also highly influenced by a climate niche shift. In the context of previous studies, a deep divergence in cpDNA sequences between Chinese + Korean and Japanese populations of C. japonicum may be taken as an example of the speciation events of the CJK flora since the late Neogene that have led to its current species richness.This study was supported by the Biodiversity Survey, Observation and Assessment Program of the Ministry of Ecology and Environment of China to HZT and by Basic Science Program through the National Research Foundation of Korea (NRF-2017R1A2B4012215) to MGC, and funded by the Ministry of Science and ICT of the Republic of Korea (NRF-2020R1I1A3074635) to MYC.INTRODUCTION MATERIALS AND METHODS Study species Population sampling DNA extraction cpDNA-PCR optimum primer selection cpDNA sequence alignment and assembly Haplotype distribution, phylogenetic analyses, and genetic diversity Genetic differentiation and structure Mismatch distribution analysis, neutrality detection, and demographic history ENM and population connectivity Niche comparisons in E-space RESULTS Haplotype distribution and phylogeny Genetic diversity Genetic differentiation and structure Mismatch distribution analysis, neutrality detection, and demographic history ENM and population connectivity Niche comparisons in E-space DISCUSSION Deep genetic and climatic divergence of Cypripedium sect. Flabellinervia in the CJK region: taxonomic considerations Haplotype and nucleotide diversity in Cypripedium sect. Flabellinervia: inference of glacial refugia and demographic history Origin of Korean populations of Cypripedium japonicum Origin of Cypripedium formosanum CONCLUSIONS AUTHOR CONTRIBUTIONS ACKNOWLEDGEMENTS Appendix 1: The cpDNA sequence information of Cypripedium sect. Flabellinervia deposited in the GenBank databas

    Strongyloidiasis Presenting as Yellowish Nodules in Colonoscopy of an Immunocompetent Patient

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    Strongyloides stercoralis is endemic to tropical and subtropical regions, and infections are usually asymptomatic. However, immunocompromised patients, such as those receiving immunosuppressive therapy, high-dose steroids, or chemotherapy, can develop fatal hyperinfections. An 84-year-old man without any symptoms was diagnosed with strongyloidiasis during a regular screening colonoscopy. His medical history only involved a gastric endoscopic submucosal dissection for early gastric cancer 6 months previously. Few cases have been published about asymptomatic strongyloidiasis diagnosed in an immunocompetent host via endoscopic mucosal resection with characteristic colonoscopic findings. We report a case of colon-involved asymptomatic strongyloidiasis with specific colonic findings of yellowish-white nodules. This finding may be an important marker of S. stercoralis infection, which could prevent hyperinfections
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