50 research outputs found

    Equivalence Between Vector Meson Dominance and Unitarised Chiral Perturbation Theory

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    It is explicitly shown that either the approximate solution of the integral equation for the inverse of the pion form facto,r or the result of the Padeˊ\text{\'e} approximant method of resumming the one loop Chiral Perturbation Theory (CPTH) are equivalent to the standard vector meson dominance (VMD) models, using the vector meson coupling to two pseudoscalars given by the KSRF relation. Inconsistencies between the one loop CPTH and its unitarised version (or the VMD model) are pointed out. The situation is better for the CPTH calculation of the scalar form factor and the related S-wave ππ\pi \pi scattering. The branching ratios of τ→π+π0ν\tau \to \pi^+ \pi^0 \nu , τ→Kπν\tau \to K \pi \nu , τ→K+ην\tau \to K^+ \eta \nu and \tau \to K^+ \bar{K^0} \nu\) using only two inputs as the \(\rho\) and \(K^*\) masses, or the two corresponding rms radii, agree with the experimental data. Using the same number of parameters, the corresponding one loop CPTH calculation cannot explain the \tau$ data

    Influence of magnetic field on properties of electrodeposited FeCo layer

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    Effect of magnetic field on the electrodeposition of FeCo layers has been investigated with respect to the orientation of the magnetic field to surface electrode e.g magnetic field is parallel and perpendicular to electrode. Electrochemical behaviours, morphology, composition, structure and magnetic properties were investigated using cyclic voltammogram (CV), Scanning Electron Microscopy (SEM), Energy Dispersion Spectroscopy (EDS), X-Ray Diffractometer (XRD), Vibrating Sample Magnetometer (VSM). Results show that morphology and structure of the deposited layers are not effected by external magnetic field. Meanwhile, the Fe content of the layer decreases by following sequence CFe(B=0)CFe(B//)CFe(^), resulting in the following sequence of coerciviy HC(B=0) HC (B//) HC (^). These results were explained based on the magnetohydronamic (MHD) effect caused by the Lorentz force () when magnetic field is superimposed

    Studying the thermo-gas-dynamic process in a muzzle brake compensator

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    To reduce the recoil and improve the stability of small arms, a muzzle brake compensator is attached to the muzzle of the barrel. This device uses the kinetic energy of the powder gas escaping from the bore after the bullet is fired. In this paper, the authors present the determination of the thermo-gas-dynamic model of the operation of a muzzle brake compensator and an example of calculating this type of muzzle device for the AK assault rifle using 7.62x39 mm ammunition. The results of the calculation allowed for obtaining the parameters of the powder gas flow in the process of flowing out of the muzzle device, as well as the change in the momentum of the powder gas's impact on the muzzle device. The model proposed in the article provides the basis for a quantitative evaluation of the effectiveness of using the muzzle device in stabilizing infantry weapons when firing

    Effect of bacteriophage on histopathology and disease resistance of Whiteleg shrimp (Litopenaeus vannamei) infected by Vibrio parahaemolyticus

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    Vibrio parahaemolyticus is the causative agent of shrimp diseases, the most serious of which is acute hepatopancreatic necrosis disease (AHPND). Bacteriophage is a virus of bacteria that can parasitize and destroy bacteria, so it is considered a potential alternative to antibiotics. The study was carried out to evaluate the treatment ability of bacteriophages on Litopenaeus vannamei after being infected by V. parahaemolyticus B4XOT2.2 isolated from the bottom mud of shrimp ponds infected with AHPND. The study used the histopathological survey method on shrimp at all three ages: postlarvae, adult shrimp at the ages of 30–45 days, and 55–60 days old, which were arranged into three treatments: healthy shrimp, diseased shrimp, and bacteriophage-treated shrimp. The results showed that: the concentration of Vibrio spp. in bacteriophage-treated treatment was decreased in all three groups (postlarvae, shrimp at the ages of 30–45 days, and 55–60 days old) from 3,7x103 CFU/mL to 2,2x102 CFU/mL after two days, from 4,6x104 CFU/mL to 3,3x102 CFU/mL after two days and from 4,6x104 CFU/mL to 5,6x103 CFU/mL after three days, respectively. The pathological signs and histological features of the infected shrimp samples were similar to those typical of acute hepatopancreatic necrosis disease and recovered in shrimp tissue after being treated with bacteriophages such as the hepatopancreas was also darker, the intestines gradually filled, no hematoma around the tubules were found, in the lumen of the tube reduced sloughing cells and blood cells, no melanization was observed

    Factors associated with 90-day mortality in Vietnamese stroke patients: Prospective findings compared with explainable machine learning, multicenter study

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    The prevalence and predictors of mortality following an ischemic stroke or intracerebral hemorrhage have not been well established among patients in Vietnam. 2885 consecutive diagnosed patients with ischemic stroke and intracerebral hemorrhage at ten stroke centres across Vietnam were involved in this prospective study. Posthoc analyses were performed in 2209 subjects (age was 65.4 ± 13.7 years, with 61.4% being male) to explore the clinical characteristics and prognostic factors associated with 90-day mortality following treatment. An explainable machine learning model using extreme gradient boosting and SHapley Additive exPlanations revealed the correlation between original clinical research and advanced machine learning methods in stroke care. In the 90 days following treatment, the mortality rate for ischemic stroke was 8.2%, while for intracerebral hemorrhage, it was higher at 20.5%. Atrial fibrillation was an elevated risk of 90-day mortality in the ischemic stroke patient (OR 3.09; 95% CI 1.90–5.02, p 0.05). The baseline NIHSS score was a significant predictor of 90-day mortality in both patient groups. The machine learning model can predict a 0.91 accuracy prediction of death rate after 90 days. Age and NIHSS score were in the top high risks with other features, such as consciousness, heart rate, and white blood cells. Stroke severity, as measured by the NIHSS, was identified as a predictor of mortality at discharge and the 90-day mark in both patient groups

    The institutional experience of the implementing 4DCT in NSCLC radiotherapy planning

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    Background: The study was to evaluate the effectiveness of dose distribution of four-dimensional computed tomography (4DCT) simulation. Materials and methods: The gross tumor volume (GTV) and clinical target volume (CTV) were contoured in all 10 respiratory phases of 4DCT in 30 patients with non-small cell lung cancer (NSCLC). Both 3D and 4D treatment plans were made individually for each patient using the planning volume (PTV). The PTV3D was taken from a single CTV plus the recommended margin, and the PTV4D was taken from the 4D internal target volume, including all 10 CTVs plus the setup margins. Results The mean PTV was 460 ± 179 (69–820) cm3 for 3DCT and 401 ± 167 (127–854) cm3 for 4DCT (p = 0.0018). The dose distribution (DD) of organs at risk, especially the lungs, was lower for the 4DCT simulation. The V5%, V10%, and V20% of the total lung dose for 4DCT were significantly lower for the 3DCT. However, lung V30% the heart, esophagus, and spinal cord were not significantly different. In addition, the conformity index and the dose heterogeneity index of the PTV were not significantly different. The normal tissue complication probability (NTCP) of the lung and heart was significantly lower for 4DCT than for 3DCT. Conclusions: The 4DCT simulation gives better results on the NTCP. The organs at risk, especially the lungs, receive a significantly lower DD compared with the 3DCT. The conformity index (CI), heterogeneity index (HI) and the DD to the heart, spinal cord, and esophagus were not significantly different between the two techniques

    J/\Psi \to \phi \pi \pi (K \bar{K}) decays, chiral dynamcis and OZI violation

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    We have studied the invariant mass distributions of the \pi\pi and K \bar{K} systems for invariant masses up to 1.2 GeV from the J/\Psi \to \phi \pi\pi(K\bar{K}) decays. The approach exploits the connection between these processes and the \pi\pi and K\bar{K} strange and non-strange scalar form factors by considering the \phi meson as a spectator. The calculated scalar form factors are then matched with the ones from next-to-leading order chiral perturbation theory, including the calculation of the the K\bar{K} scalar form factors. Final state interactions in the J/\Psi \to \phi \pi\pi (K\bar{K}) processes are taken into account as rescattering effects in the system of the two pseudoscalar mesons. A very good agreement with the experimental data from DM2 and MARK-III is achieved. Furthermore, making use of SU(3) symmetry, the S-wave contribution to the \pi^+\pi^- event distribution in the J/\Psi \to \omega \pi^+\pi^- reaction is also given and the data up to energies of about 0.7 GeV are reproduced. These decays of the J/\Psi to a vector and a pair of pseudoscalars turn out to be very sensitive to OZI violating physics which we parametrize in terms of a direct OZI violation parameter and the chiral perturbation theory low energy constants L_4^r and L_6^r. These constants all come out very different from zero, lending further credit to the statement that the OZI rule is not operative in the scalar 0^{++} channel.Comment: revtex, 21 pages, 10 figures, extended discussion of the model in section 2 and some minor corrections, version accepted for publication in Nucl. Phys.

    Analysis of Antimicrobial Resistance in Non-typhoidal Salmonella Collected From Pork Retail Outlets and Slaughterhouses in Vietnam Using Whole Genome Sequencing.

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    Non-typhoidal salmonella (TS) remains a significant health burden worldwide. In Vietnam, pork accounts for 70% of the total meat consumed, and contamination with Salmonella is high. High levels of antimicrobial resistance (AMR) have emerged among porcine NTS and of particular concern is the emergence of colistin resistance, a "last defense" antibioic against multi-drug resistant (MDR) Gram-negative pathogens. This study aimed to investigate the antibiotic susceptibility of 69 NTS isolates collected from the pork retail outlets and slaughterhouses in Vietnam during 2014 a nd 2018/19. Phenotypic testing and whole genome sequencing was used to assess the serotype and AMR gene profiles of the 69 NTS isolates. Seventeen different serotypes were identified, of which S. enterica subsp enterica serotype Typhimurium was the most common followed by S. ser. Rissen, S. ser. London, S. ser. Anatum, and S. ser. Derby. Phenotype AMR was common with 41 (59.4%) isolates deemed MDR. MDR strains were most common in slaughterhouses (83%) and supermarkets (75%) and lowest in traditional markets (38%) and convenience stores (40%). Colistin resistance was identified in 18 strains (15 resistant, three intermediate) with mcr-1 identified in seven isolates (S. ser. Meleagridis, S. Rissen, S. Derby) and mcr-3 in two isolates (S. Typhimurium). This includes the first mcr positive S. Meleagridis to our knowledge. Surprisingly, boutique stores had high levels (60%) of MDR isolates including 5/20 isolates with mcr-1. This study demonstrates that pork from modern retail stores classed as supermarkets or boutique (with pork claiming to be high quality, traceable, environmentally friendly marketed toward higher income consumers) still contained NTS with high levels of AMR

    Bethe-Salpeter Approach for Unitarized Chiral Perturbation Theory

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    The Bethe-Salpeter equation restores exact elastic unitarity in the s−s- channel by summing up an infinite set of chiral loops. We use this equation to show how a chiral expansion can be undertaken in the two particle irreducible amplitude and the propagators accomplishing exact elastic unitarity at any step. Renormalizability of the amplitudes can be achieved by allowing for an infinite set of counter-terms as it is the case in ordinary Chiral Perturbation Theory. Crossing constraints can be imposed on the parameters to a given order. Within this framework, we calculate the leading and next-to-leading contributions to the elastic ππ\pi \pi scattering amplitudes, for all isospin channels, and to the vector and scalar pion form factors in several renormalization schemes. A satisfactory description of amplitudes and form factors is obtained. In this latter case, Watson's theorem is automatically satisfied. From such studies we obtain a quite accurate determination of some of the ChPT SU(2)−SU(2)-low energy parameters ({\bar l}_1 - {\bar l}_2 = -6.1\er{0.1}{0.3} and lˉ6=19.14±0.19{\bar l}_6= 19.14 \pm 0.19). We also compare the two loop piece of our amplitudes to recent two--loop calculations.Comment: 63 pages, 9 figures. Some discussions on off-shell ambiguities and convergence of the expansion adde
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