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Characterization of bright betatron radiation generated by direct laser acceleration of electrons in plasma of near critical density

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matter and Radiation at extremes 2024年第2期9卷 26-35页

作者： J.Cikhardt m.Gyrdymov S.Zähter P.Tavana m.m.Günther N.Bukharskii N.Borisenko J.Jacoby X.F.Shen A.Pukhov N.e.Andreev O.N.Rosmej Faculty of electrical engineering Czech Technical University in Prague16627 Prague 6Czech Republic Goethe University FrankfurtMax-von-Laue-Straße 160438 Frankfurt am MainGermany GSI Helmholtzzentrum für Schwerionenforschung GmbH Planckstraße 164291 DarmstadtGermany Focused energy GmbH Im Tiefen See 4564293 DarmstadtGermany National Research Nuclear University mePhI Kashirskoe shosse 31115409 MoscowRussian Federation Lebedev Physical Institute RAS Leninskiy Prospekt 53119991 MoscowRussian Federation Heinrich-Heine-University Düsseldorf Universitätsstrasse 1DüsseldorfGermany Joint Institute for High Temperatures RASIzhorskaya st.13Bldg.2125412 MoscowRussian Federation moscow Institute of Physics and Technology Institutskiy Pereulok 9141700 DolgoprudnyRussia

Directed x-rays produced in the interaction of sub-picosecond laser pulses of moderate relativistic intensity with plasma of near-critical density are investigated. Synchrotron-like (betatron) radiation occurs in the process of direct laser acceleration (DLA) of electrons in a relativisticlaser channel when the electrons undergo transverse betatron oscillations in self-generated quasi-static electric and magnetic fields. In anexperiment at the PHeLIX laser system, high-current directed beams of DLA electrons with a mean energy ten times higher than the ponderomotive potential and maximum energy up to 100 meV were measured at 10^(19) W/cm^(2)laser intensity. The spectrum of directed x-raysin the range of 5–60 keV was evaluated using two sets of Ross filters placed at 0°and 10°to the laser pulse propagation axis. The differential x-ray absorption method allowed for absolute measurements of the angular-dependent photon fluence. We report 10^(13) photons/sr withenergies >5 keV measured at 0°to the laser axis and a brilliance of 10^(21) photons s^(−1) mm^(−2) mrad−2(0.1%BW)−1. The angular distributionof the emission has an FWHm of 14°–16°. Thanks to the ultra-high photon fluence, point-like radiation source, and ultra-short emissiontime, DLA-based keV backlighters are promising for various applications in high-energy-density research with kilojoule petawatt-class laserfacilities.

关键词： laser acceleration critical

FSCIL-eACA: Few-Shot Class-Incremental Learning Network Based on embedding Augmentation and Classifier Adaptation for Image Classification

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Chinese Journal of electronics 2024年第1期33卷 139-152页

作者： Ruru ZHANG Haihong e meina SONG School of Computer Science Beijing University of Posts and Telecommunications education Department Information Network engineering Research Center Beijing University of Posts and Telecommunications

The ability to learn incrementally is critical to the long-term operation of AI systems. Benefiting from the power of few-shot class-incremental learning(FSCIL), deep learning models can continuously recognize new classes with only a few samples. The difficulty is that limited instances of new classes will lead to overfitting and exacerbate the catastrophic forgetting of the old classes. most previous works alleviate the above problems by imposing strong constraints on the model structure or parameters, but ignoring embedding network transferability and classifier adaptation(CA), failing to guarantee the efficient utilization of visual features and establishing relationships between old and new classes. In this paper, we propose a simple and novel approach from two perspectives: embedding bias and classifier bias. The method learns an embedding augmented(eA) network with cross-class transfer and class-specific discriminative abilities based on self-supervised learning and modulated attention to alleviate embedding bias. Based on the adaptive incremental classifier learning scheme to realize incremental learning capability,guiding the adaptive update of prototypes and feature embeddings to alleviate classifier bias. We conduct extensive experiments on two popular natural image datasets and two medical datasets. The experiments show that our method is significantly better than the baseline and achieves state-of-the-art results.

关键词： Training Adaptation models Visualization Image recognition Prototypes Self-supervised learning Power capacitors

Identific tion of quantitative trait loci and associated candidate genes for pregnancy success in Angus–Brahman crossbred heifers

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Journal of Animal Science and Biotechnology 2024年第1期15卷 162-170页

作者： Quinn A.Hoorn Gabriel A.Zayas eduardo e.Rodriguez Laura m.Jensen Raluca G.mateescu Peter J.Hansen Department of Animal Sciences Donald Henry Barron Reproductive and Perinatal Biology Research Programand the Genetics InstituteUniversity of FloridaGainesvilleFLUSA School of Applied Systems Biology La Trobe UniversityBundooraVIC 3083Australia

Background In beef cattle, more than 50% of the energy input to produce a unit of beef is consumed by the female that produced the calf. Development of genomic tools to identify females with high genetic merit for reproductive function could increase the profitability and sustainability of beef *** Genome-wide association studies(GWAS) were performed using a single-step genomic best linear unbiased prediction approach on pregnancy outcome traits from a population of Angus–Brahman crossbred heifers. Furthermore, a validation GWAS was performed using data from another farm. Heifers were genotyped with the Bovine GGP F250 array that contains 221,077 SNPs. In the discovery population, heifers were bred in winter breeding seasons involving a single round of timed artificial insemination(AI) followed by natural mating for 3 months. Two phenotypes were analyzed: pregnancy outcome to first-service AI(PAI;n = 1,481) and pregnancy status at the end of the breeding season(PeBS;n = 1,725). The heritability was estimated as 0.149 and 0.122 for PAI and PeBS, respectively. In the PAI model, one quantitative trait locus(QTL), located between 52.3 and 52.5 mb on BTA7, explained about 3% of the genetic variation, in a region containing a cluster of γ-protocadherin genes and SLC25A2. Other QTLs explaining between 0.5% and 1% of the genetic variation were found on BTA12 and 25. In the PeBS model, a large QTL on BTA7 was synonymous with the QTL for PAI, with minor QTLs located on BTA5, 9, 10, 11, 19, and 20. The validation population for pregnancy status at the end of the breeding season were Angus–Brahman crossbred heifers bred by natural mating. In concordance with the discovery population, the large QTL on BTA7 and QTLs on BTA10 and 12 were *** In summary, QTLs and candidate SNPs identified were associated with pregnancy outcomes in beef heifers, including a large QTL associated with a group of protocadherin genes. Confirmation of these associations

关键词： Beef cattle Fertility GWAS QTL

Development of an active-site titrant for SARS-CoV-2 main protease as an indispensable tool for evaluating enzyme kinetics

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Acta Pharmaceutica Sinica B 2024年第5期14卷 2349-2357页

作者： Rabea Voget Julian Breidenbach Tobias Claff Alexandra Hingst Katharina Sylvester Christian Steinebach Lan Phuong Vu Renato H.Weiße Ulrike Bartz Norbert Sträter Christa e.müller michael Gütschow Pharmaceutical Institute Pharmaceutical&Medicinal ChemistryUniversity of BonnBonn 53121Germany Institute of Bioanalytical Chemistry Center for Biotechnology and BiomedicineLeipzig UniversityLeipzig 04103Germany Department of Natural Sciences University of Applied Sciences Bonn-Rhein-SiegRheinbach 53359Germany

A titrant for the SARS-CoV-2 main protease(m^(pro))was developed that enables,for the first time,the exact determination of the concentration of the enzymatically active m^(pro) by active-site *** covalent binding mode of the tetrapeptidic titrant was elucidated by the determination of the crystal structure of the enzyme–titrant *** fluorogenic substrates of m^(pro),including a prototypical,internally quenched Dabcyl-eDANS peptide,were compared in terms of solubility under typical assay *** exploiting the new titrant,key kinetic parameters for the m^(pro)-catalyzed cleavage of these substrates were determined.

关键词： COVID-19 SARS-CoV-2 main protease Peptide nitriles Fluorogenic substrates Active-site titration X-ray crystallography Inner filter effect

In vivo and in vitro study of resorbable magnesium wires for medical implants:mg purity,surface quality,Zn alloying and polymer coating

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Journal of magnesium and Alloys 2024年第6期12卷 2472-2488页

作者： K.Tesar J.Luňácková m.Jex m.Žaloudková R.Vrbová m.Bartoš P.Klein L.Vištejnová J.Dušková e.Filová Z.Sucharda m.Steinerová S.Habr K.Balík A.Singh Department of materials Faculty of Nuclear Sciences and Physical EngineeringCzech Technical University in PragueTrojanova 13Prague 12000Czech Republic Institute of Physics Czech Academy of SciencesNa Slovance 2Prague 18221Czech Republic Institute of Dental medicine First Faculty of MedicineCharles University and General University Hospital in PragueKaterinská32Prague 12801Czech Republic Department of Physics Faculty of Nuclear Sciences and Physical EngineeringCzech Technical University in PragueBrehová7Prague 11519Czech Republic Department of Composites and Carbon materials Institute of Rock Structure and MechanicsCzech Academy of SciencesV Holešovickách 41Prague 18209Czech Republic Institute of Anatomy First Faculty of MedicineCharles UniversityU Nemocnice 3Prague 12800Czech Republic Biomedical Center Faculty of Medicine in PilsenCharles UniversityAlej Svobody 76Pilsen 32300Czech Republic Department of Pathological Physiology Faculty of Medicine in PilsenCharles UniversityAlej Svobody 7632300 PilsenCzech Republic Department of Histology and embryology Faculty of Medicine in PilsenCharles UniversityAlej Svobody 7632300 PilsenCzech Republic Institute of Pathology First Faculty of MedicineCharles University and General University Hospital in PragueStudnickova 2Prague 12800Czech Republic Department of Biomaterials and Tissue engineering Institute of PhysiologyCzech Academy of SciencesVidenska 1083Prague 14200Czech Republic Research Center for Structural materials National Institute for Materials Science1-2-1 SengenTsukuba 305-0047Japan

magnesium is an excellent material in terms of biocompatibility and its corrosion products can serve as an active source for new bone ***,localized corrosion and H_(2)generation limit the potential of mg-based *** low-alloyed mg-Zn wires can strongly reduce problems with large H_(2)bubbles and improve the mechanical properties considerably while maintaining excellent long-term *** pickling and a polymer coating can be effectively used to lower the rate of in vivo *** this work,microstructural,mechanical,and in vitro characterization of 250μm and 300μm extruded wires made from ultra-pure mg,commercially pure mg,mg-0.15Zn,mg-0.4Zn and mg-1Zn was ***,mg-0.4Zn wires together with a variant coated with a copolymer of L-lactide andε-caprolactone were tested in vivo on artificially damaged Wistar rat *** on the observed mg-induced osteogenesis,polymer-coated mg wires with a small addition of Zn are a perspective material for bone-support applications,such as cerclage and fixation wires.

关键词： magnesium Resorbable mg wire mg-Zn implant degradation Biocompatibility study Zn grain boundary segregation

SARS-CoV-2 triggers Dickkopf-1(Dkk-1)modulation of T helper cells and lung pathology in mice

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Genes & Diseases 2024年第4期11卷 9-12页

作者： Yifan Wu Freedom m.Green Stephen A.Shaw Lauren J.Bonilla Shannon e.Ronca maria elena Bottazzi Farrah Kheradmand Jill e.Weatherhead Department of Pathology&Immunology One Baylor PlazaHoustonTX 77030USA Department of Pediatrics One Baylor PlazaHoustonTX 77030USA Department of medicine One Baylor PlazaHoustonTX 77030USA National School of Tropical medicine One Baylor PlazaHoustonTX 77030USA molecular Virology&microbiology One Baylor PlazaHoustonTX77030USA Biologyof Inflammation Center Baylor College of MedicineOne BaylorPlazaHoustonTX77030USA michael e.DeBakey VA Center for Translational Research on Inflammatory Diseases HoustonTX 77030USA

Severe acute respiratory syndrome coronavirus 2(SARSCov-2)is the etiologic agent of the coronavirus disease 19(COVID-19)*** viral infections like SARS-CoV-2,a robust anti-viral type 1 immune response,including upregulation of type 1 CD4+T helper cells(Th1),is required for effective viral clearance while minimizing end-organ pathology and collateral tissue damage.

关键词： pathology acute respiratory

Investigating the impact of the universal function of the nuclear proximity potential in heavy-ion fusion cross sections

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Communications in Theoretical Physics 2024年第5期76卷 86-93页

作者： R Gharaei e Sarvari Department of Physics Sciences FacultyHakim Sabzevari UniversityPO Box 397SabzevarIran Department of Physics Faculty of ScienceFerdowsi University of MashhadPO Box 91775-1436MashhadIran Science Faculty Department of PhysicsTarbiat Modares UniversityTehranIran

The fusion barriers and cross sections of 15 colliding systems with 320≤Z_(1)Z_(2)≤1512 are investigated in detail to understand the influence of the universal function of proximity potential formalism in the heavy-ion fusion *** realize this goal,we select three versions of the phenomenological proximity potentials,including Prox.77,Zhang 2013,and Guo 2013,to calculate the nucleus-nucleus *** experimental fusion cross sections for the selected reactions are analyzed using the standard coupled-channel calculations,including couplings to the low-lying 2^(+)and 3^(-)states in the target and *** calculated results show that the universal functions of the Guo 2013 and Prox.77 models provide the lowest and highest fusion barriers,*** addition,it is found that the height of the fusion barriers is enhanced by increasing the mass number of the projectile from light to heavy *** highest sensitivity to the mass number of the projectile belongs to the results of Prox.77.A discussion is also presented on the influence of the universal function on the radial behavior of the interaction potential in the allowed region for overlapping *** results reveal that the best fit to the experimental data of the fusion cross sections for the reactions involving light and medium nuclei is obtained using the universal function of the Zhang 2013 *** the heavier systems,the results of the Guo 2013 model at sub-barrier energies provide a good description of the available data.

关键词： fusion reactions proximity-type potentials universal function coupled-channel calculations

event-triggered H_(∞) consensus control for input-constrained multi-agent systems via reinforcement learning

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Control Theory and Technology 2024年第1期22卷 25-38页

作者： Jinxuan Zhang Chang-e Ren College of Information engineering Capital Normal UniversityBeijing100089China

This article presents an event-triggered H_(∞) consensus control scheme using reinforcement learning (RL) for nonlinear second-order multi-agent systems (mASs) with control constraints. First, considering control constraints, the constrained H_(∞) consensus problem is transformed into a multi-player zero-sum game with non-quadratic performance functions. Then, an event-triggered control method is presented to conserve communication resources and a new triggering condition is developed for each agent to make the triggering threshold independent of the disturbance attenuation level. To derive the optimal controller that can minimize the cost function in the case of worst disturbance, a constrained Hamilton–Jacobi–Bellman (HJB) equation is defined. Since it is difficult to solve analytically due to its strongly non-linearity, reinforcement learning (RL) is implemented to obtain the optimal controller. In specific, the optimal performance function and the worst-case disturbance are approximated by a time-triggered critic network;meanwhile, the optimal controller is approximated by event-triggered actor network. After that, Lyapunov analysis is utilized to prove the uniformly ultimately bounded (UUB) stability of the system and that the network weight errors are UUB. Finally, a simulation example is utilized to demonstrate the effectiveness of the control strategy provided.

关键词： H_(∞)optimal control Input constrains multi-agent systems(mASs) Reinforcement learning(RL)

enhancing high-temperature oxidation resistance(at 1000 °C) of nickel superalloy obtained by laser powder bed fusion via reactive electric spark treatment

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Transactions of Nonferrous metals Society of China 2024年

作者： S.K.mUKANOV m.I.PeTRZHIK A.e.KUDRYASHOV e.A.NAUmOVA F.A.BASKOV P.A.LOGINOV e.A.LeVASHOV National University of Science and Technology mISIS

The high-temperature oxidation resistance of the nickel superalloy grown by the Laser Powder Bed Fusion (LPBF) has been significantly increased as a result of in-situ formation of a thermal barrier layer (α-Al2O3+ CamoO4) during oxidative annealing of surface layers modified by electric spark treatment (eST). The reactive eST of the LPBF-built items based on nickel eP741NP alloy was carried out with low-melting Al-12%Si， Al-6%Ca-0.6%Si and Al-7%Ca-1%mn electrodes. It was found that at eST done by Al-7%Ca-1%mn electrode an intermetallic (β-NiAl + γ’-Ni3Al) 15 microns thick layer reinforced by spherical oxide (Came)O nanoparticles was formed. Formation of that structure increases the wear resistance of LPBF nickel superalloy by 4.5 times. Further oxidative annealing at 1000 °C lead to a formation of continuous two-layered coating with an inner layer of α-Al2O3and an outer layer of CamoO4， which together act as an effective barrier preventing the diffusion of oxygen into the volume of the superalloy.

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