211 research outputs found
Quenched chiral logarithms in lattice QCD with exact chiral symmetry
We examine quenched chiral logarithms in lattice QCD with overlap Dirac
quark. For 100 gauge configurations generated with the Wilson gauge action at on the lattice, we compute quenched quark
propagators for 12 bare quark masses. The pion decay constant is extracted from
the pion propagator, and from which the lattice spacing is determined to be
0.147 fm. The presence of quenched chiral logarithm in the pion mass is
confirmed, and its coefficient is determined to be , in agreement with the theoretical estimate in quenched chiral perturbation
theory. Further, we obtain the topological susceptibility of these 100 gauge
configurations by measuring the index of the overlap Dirac operator. Using a
formula due to exact chiral symmetry, we obtain the mass in quenched
chiral perturbation theory, Mev, and an estimate
of , which is in good agreement with that
determined from the pion mass.Comment: 24 pages, 6 EPS figures; v2: some clarifications added, to appear in
Physical Review
Ionizing radiation absorption of vascular surgeons during endovascular procedures
ObjectiveEndovascular procedures have become an integral part of a vascular surgeonâs practice. The exposure of surgeons to ionizing radiation and other safety issues have not been well studied. We investigated the radiation exposure of a team of vascular surgeons in an active endovascular unit and compared yearly dosages absorbed by various body parts among different surgeons. Patientsâ radiation exposure was also assessed.MethodsThe radiation absorption of a team of vascular surgeons was prospectively monitored in a 12-month period. During each endovascular procedure, the effective body, eye, and hand radiation doses of all participating surgeons were measured by mini-thermoluminescent dosimeters (TLD) attached at the chest level under a lead apron, at the forehead at eye level, and at the hand. The type of procedure, fluoroscopy machine, fluoroscopy time, and personal and operating theatre radiation protection devices used in each procedure were also recorded. One TLD was attached to the patientâs body near the operative site to measure the patientâs dose. The yearly effective body, eye, and hand dose were compared with the safety limits of radiation for occupational exposure recommended by the International Commission on Radiation Protection (ICRP). The radiation absorption of various body parts per minute of fluoroscopy was compared among different surgeons.ResultsA total of 149 consecutive endovascular procedures were performed, including 30 endovascular aortic repairs (EVAR), 58 arteriograms with and without embolization (AGM), and 61 percutaneous transluminal angioplasty and stent (PTA/S) procedures. The cumulative fluoroscopy time was 1132 minutes. The median yearly effective body, eye, and hand dose for the surgeons were 0.20 mSv (range, 0.13 to 0.27 mSv), 0.19 mSv (range, 0.10 to 0.33 mSv) and 0.99 mSv (0.29 to 1.84 mSv) respectively, which were well below the safety limits of the ICRP. The mean body, eye, and hand dose of the chief surgeon per procedure were highest for EVAR. A significant discrepancy was observed for the average hand dose per minute of fluoroscopy among different surgeons. The mean radiation absorption of patients who underwent EVAR, AGM, and PTA/S was 12.7 mSv, 13.6 mSv, and 3.4 mSv, respectively.ConclusionWith current radiation protection practice, the radiation absorbed by vascular surgeons with a high endovascular workload did not exceed the safety limits recommended by ICRP. Variations in practice, however, can result in significant discrepancy of radiation absorption between surgeons
Identification of QTLs Associated with Callogenesis and Embryogenesis in Oil Palm Using Genetic Linkage Maps Improved with SSR Markers.
Clonal reproduction of oil palm by means of tissue culture is a very inefficient process. Tissue culturability is known to be genotype dependent with some genotypes being more amenable to tissue culture than others. In this study, genetic linkage maps enriched with simple sequence repeat (SSR) markers were developed for dura (ENL48) and pisifera (ML161), the two fruit forms of oil palm, Elaeis guineensis. The SSR markers were mapped onto earlier reported parental maps based on amplified fragment length polymorphism (AFLP) and restriction fragment length polymorphism (RFLP) markers. The new linkage map of ENL48 contains 148 markers (33 AFLPs, 38 RFLPs and 77 SSRs) in 23 linkage groups (LGs), covering a total map length of 798.0 cM. The ML161 map contains 240 markers (50 AFLPs, 71 RFLPs and 119 SSRs) in 24 LGs covering a total of 1,328.1 cM. Using the improved maps, two quantitative trait loci (QTLs) associated with tissue culturability were identified each for callusing rate and embryogenesis rate. A QTL for callogenesis was identified in LGD4b of ENL48 and explained 17.5% of the phenotypic variation. For embryogenesis rate, a QTL was detected on LGP16b in ML161 and explained 20.1% of the variation. This study is the first attempt to identify QTL associated with tissue culture amenity in oil palm which is an important step towards understanding the molecular processes underlying clonal regeneration of oil palm
Ad hoc influenza vaccination during years of significant antigenic drift in a tropical city with 2 seasonal peaks
We evaluated the acceptability of an additional ad hoc influenza vaccination among the health care professionals following seasons with significant antigenic drift. Self-administered, anonymous surveys were performed by hard copy questionnaires in public hospitals, and by an on-line platform available to all healthcare professionals, from April 1st to May 31st, 2015. A total of 1290 healthcare professionals completed the questionnaires, including doctors, nurses, and allied health professionals working in both the public and private systems. Only 31.8% of participating respondents expressed an intention to receive the additional vaccine, despite that the majority of them agreed or strongly agreed that it would bring benefit to the community (88.9%), save lives (86.7%), reduce medical expenses (76.3%), satisfy public expectation (82.8%), and increase awareness of vaccination (86.1%). However, a significant proportion expressed concern that the vaccine could disturb the normal immunization schedule (45.5%); felt uncertain what to do in the next vaccination round (66.0%); perceived that the summer peak might not occur (48.2%); and believed that the summer peak might not be of the same virus (83.5%). Furthermore, 27.8% of all respondents expected that the additional vaccination could weaken the efficacy of previous vaccinations; 51.3% was concerned about side effects; and 61.3% estimated that there would be a low uptake rate. If the supply of vaccine was limited, higher priority groups were considered to include the elderly aged â„65 years with chronic medical conditions (89.2%), the elderly living in residential care homes (87.4%), and long-stay residents of institutions for the disabled (80.7%). The strongest factors associated with accepting the additional vaccine included immunization with influenza vaccines in the past 3 years, higher perceived risk of contracting influenza, and higher perceived severity of the disease impact. The acceptability to an additional ad hoc influenza vaccination was low among healthcare professionals. This could have a negative impact on such additional vaccination campaigns since healthcare professionals are a key driver for vaccine acceptance. The discordance in perceived risk and acceptance of vaccination regarding self versus public deserves further evaluation
Identification of alpha-enolase as an autoantigen in lung cancer: Its overexpression is associated with clinical outcomes
Purpose: Although existence of humoral immunity has been previously shown in malignant pleural effusions, only a limited number of immunogenic tumor-associated antigens (TAA) have been identified and associated with lung cancer. In this study, we intended to identify more TAAs in pleural effusion-derived tumor cells. Experimental Design: Using morphologically normal lung tissues as a control lysate in Western blotting analyses, 54 tumor samples were screened with autologous effusion antibodies. Biochemical purification and mass spectrometric identification of TAAs were done using established effusion tumor cell lines as antigen sources. We identified a p48 antigen as of-enolase (ENO1). Semiquantitative immunohistochemistry was used to evaluate expression status of ENO1 in the tissue samples of 80 patients with non-small cell lung cancer (NSCLC) and then correlated with clinical variables. Results: Using ENO1-specifc antiserum, up-regulation of ENO1 expression in effusion tumor cells from 11 of 17 patients was clearly observed compared with human normal lung primary epithelial and non-cancer-associated effusion cells. Immunohistochemical studies consistently showed high level of ENO1 expression in all the tumors we have examined thus far. Log-rank and Cox's analyses of ENO1 expression status revealed that its expression level in primary tumors was a key factor contributing to overall- and progression-free survivals of patients (P < 0.05). The same result was also obtained in the early stage of NSCLC patients, showing that tumors expressing relatively higher ENO1 level were tightly correlated with poorer survival outcomes. Conclusions: Our data strongly support a prognostic role of ENO1 in determining tumor malignancy of patients with NSCLC
Increased Detection of Emergent Recombinant Norovirus GII.P16-GII.2 Strains in Young Adults, Hong Kong, China, 2016â2017
A new recombinant norovirus GII.P16-GII.2 outnumbered pandemic GII.4 as the predominant GII genotype in the winter of 2016â2017 in Hong Kong, China. Half of hospitalized case-patients were older children and adults, including 13 young adults. This emergent norovirus targets a wider age population compared with circulating pandemic GII.4 strains
Meta-analysis of genome-wide association studies identifies eight new loci for type 2 diabetes in east Asians
We conducted a three-stage genetic study to identify susceptibility loci for type 2 diabetes (T2D) in east Asian populations. We followed our stage 1 meta-analysis of eight T2D genome-wide association studies (6,952 cases with T2D and 11,865 controls) with a stage 2 in silico replication analysis (5,843 cases and 4,574 controls) and a stage 3 de novo replication analysis (12,284 cases and 13,172 controls). The combined analysis identified eight new T2D loci reaching genome-wide significance, which mapped in or near GLIS3, PEPD, FITM2-R3HDML-HNF4A, KCNK16, MAEA, GCC1-PAX4, PSMD6 and ZFAND3. GLIS3, which is involved in pancreatic beta cell development and insulin gene expression1,2, is known for its association with fasting glucose levels3,4. The evidence of an association with T2D for PEPD5 and HNF4A6,7 has been shown in previous studies. KCNK16 may regulate glucose-dependent insulin secretion in the pancreas. These findings, derived from an east Asian population, provide new perspectives on the etiology of T2D
Search for light long-lived neutral particles that decay to collimated pairs of leptons or light hadrons in pp collisions at sâ = 13 TeV with the ATLAS detector
A search for light long-lived neutral particles with masses in the O(MeVâGeV) range is presented. The analysis targets the production of long-lived dark photons in the decay of a Higgs boson produced via gluonâgluon fusion or in association with a W boson. Events that contain displaced collimated Standard Model fermions reconstructed in the calorimeter or muon spectrometer are selected in 139 fbâ1 of sâ = 13 TeV pp collision data collected by the ATLAS detector at the LHC. Background estimates for contributions from Standard Model processes and instrumental effects are extracted from data. The observed event yields are consistent with the expected background. Exclusion limits are reported on the production cross-section times branching fraction as a function of the mean proper decay length cÏ of the dark photon, or as a function of the dark-photon mass and kinetic mixing parameter that quantifies the coupling between the Standard Model and potential hidden (dark) sectors. A Higgs boson branching fraction above 1% is excluded at 95% CL for a Higgs boson decaying into two dark photons for dark-photon mean proper decay lengths between 10 mm and 250 mm and dark photons with masses between 0.4 GeV and 2 GeV
Inclusive-photon production and its dependence on photon isolation in pp collisions at sâ = 13 TeV using 139 fbâ1 of ATLAS data
Measurements of differential cross sections are presented for inclusive isolated-photon production in pp collisions at a centre-of-mass energy of 13 TeV provided by the LHC and using 139 fbâ1 of data recorded by the ATLAS experiment. The cross sections are measured as functions of the photon transverse energy in different regions of photon pseudorapidity. The photons are required to be isolated by means of a fixed-cone method with two different cone radii. The dependence of the inclusive-photon production on the photon isolation is investigated by measuring the fiducial cross sections as functions of the isolation-cone radius and the ratios of the differential cross sections with different radii in different regions of photon pseudorapidity. The results presented in this paper constitute an improvement with respect to those published by ATLAS earlier: the measurements are provided for different isolation radii and with a more granular segmentation in photon pseudorapidity that can be exploited in improving the determination of the proton parton distribution functions. These improvements provide a more in-depth test of the theoretical predictions. Next-to-leading-order QCD predictions from JETPHOX and SHERPA and next-to-next-to-leading-order QCD predictions from NNLOJET are compared to the measurements, using several parameterisations of the proton parton distribution functions. The measured cross sections are well described by the fixed-order QCD predictions within the experimental and theoretical uncertainties in most of the investigated phase-space region
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