Methods for a blind analysis of isobar data collected by the STAR collaboration

In 2018,the STAR collaboration collected data from^(96)_(44)Ru+^(96)_(44)Ru and^(96)_(40)Zr+^(96)_(40)Zr at√^(S)NN=200 Ge V to search for the presence of the chiral magnetic effect in collisions of nuclei.The isobar collision species alternated frequently between 9644 Ru+^(96)_(44)Ru and^(96)_(40)Zr+^(96)_(40)Zr.In order to conduct blind analyses of studies related to the chiral magnetic effect in these isobar data,STAR developed a three-step blind analysis procedure.Analysts are initially provided a"reference sample"of data,comprised of a mix of events from the two species,the order of which respects time-dependent changes in run conditions.After tuning analysis codes and performing time-dependent quality assurance on the reference sample,analysts are provided a species-blind sample suitable for calculating efficiencies and corrections for individual≈30-min data-taking runs.For this sample,species-specific information is disguised,but individual output files contain data from a single isobar species.Only run-by-run corrections and code alteration subsequent to these corrections are allowed at this stage.Following these modifications,the"frozen"code is passed over the fully un-blind data,completing the blind analysis.As a check of the feasibility of the blind analysis procedure,analysts completed a"mock data challenge,"analyzing data from Au+Au collisions at√^(S)NN=27 Ge V,collected in 2018.The Au+Au data were prepared in the same manner intended for the isobar blind data.The details of the blind analysis procedure and results from the mock data challenge are presented.

黄爱龙教授:“新型冠状病毒感染诱导机体特异性体液免疫反应的新认识”

由严重急性呼吸综合征冠状病毒2(SARS-CoV-2)引起的2019年新型冠状病毒肺炎(COVID-19)疫情目前仍在全球大范围流行,这使全球公共卫生健康面临持续挑战。根据世界卫生组织最新实时统计数据:截至2021年3月28日,全球累计新冠肺炎确诊病例1.26亿例,累计死亡病例276.97万例。新冠肺炎疫情已对人类的健康和预期寿命等产生了巨大影响,严重损害了全球的叉流合作和稳定发展。新冠病毒感染人体后,可诱导机体产生病毒特异性的体液免疫反应,通过效应B细胞等产生大量的病毒抗原特异性抗体IgA、IgM和IgG等(含中和抗体)来控制病毒的增殖、扩散和再感染。

Unexpected creep behavior in a rejuvenated metallic glass

Rejuvenation,bringing metallic glasses(MGs)to the younger and higher energy states,provides an alternative avenue to explore the interplay between the property and microstructures of MGs.In this study,the creep behavior of the Zr_(69.5)Cu_(12)Ni_(11)Al_(7.5)MGs was experimentally examined by controlling the energy state in terms of structural rejuvenation and thermal annealing.It is found that compared to the as-cast counterpart,the annealed MG at a lower energy state exhibits a higher hardness,a smaller displacement,and a lower creep rate due to the decreased free volume and the inhibited activation of the shear transformation zone.Conversely,the rejuvenated MG at a high energy state displays lower hardness and increased free volume content,yet it demonstrates superior creep resistance compared to its as-cast counterpart,which deviates from conventional understanding.This unexpected phenomenon occurs as the initial high-content free volume annihilates during creep,and strain hardening takes precedence over strain softening as the prevailing process during creep deformation,leading to a superior creep performance in extremely rejuvenated MGs.

Hardness-thermal stability synergy in nanograined Ni and Ni alloys:Superposition of nanotwin and low-energy columnar boundary

Refining grains into nanoscale can significantly strengthen and harden metallic materials;however,nanograined metals generally exhibit low thermal stability,hindering their practical applications.In this work,we exploit the superposition of the contribution of nanotwins,low-angle grain boundaries,and microalloying to tailor superior combinations of high hardness and good thermal stability in Ni and Ni alloys.For the nanotwinned Ni having a twin thickness of∼2.9 nm and grain size of 28 nm,it exhibits a hardness over 8.0 GPa and an onset coarsening temperature of 623 K,both of which are well above those of nanograined Ni.Re/Mo microalloying can further improve the onset coarsening temperature to 773 K without comprising hardness.Our analyses reveal that high hardness is achieved via strengthen-ing offered by extremely fine nanotwins.Meanwhile,the superior thermal stability is mainly ascribed to the low driving force for grain growth induced by the low-angle columnar boundary architecture and to the additional pinning effect on the migration of twin/columnar boundaries provided by minor Re/Mo solutes.The present work not only reveals a family of nanotwinned metals possessing the combination of ultra-high hardness and high thermal stability but also provides a strategy for tailoring properties of metallic materials by pairing low-angle grain boundaries and twin boundaries.

Measurement of away-side broadening with self-subtraction of flow in Au+Au collisions at √sNN=200 GeV

High transverse momentum(pT)particle production is suppressed owing to the parton(jet)energy loss in the hot dense medium created in relativistic heavy-ion collisions.Redistribution of energy at low-to-modest pT has been difficult to measure,owing to large anisotropic backgrounds.We report a data-driven method for background evaluation and subtraction,exploiting the away-side pseudorapidity gaps,to measure the jetlike correlation shape in Au+Au collisions at √sNN=200 GeV in the STAR experiment.The correlation shapes,for trigger particles pT>3GeV/c and various associated particle pT ranges within 0.5<pT<10GeV/c,are consistent with Gaussians,and their widths increase with centrality.The results indicate jet broadening in the medium created in central heavy-ion collisions.

HIGH EPITAXIAL FERROELECTRIC RELAXOR Mn-DOPED Ba(Zr,Ti)O_(3) THIN FILMS ON MgO SUBSTRATES

Environment friendly ferroelectric relaxor Ba(Zr_(0.2)Ti_(0.8))O_(3)thin fims with the addition of 2%Mn dopant were grown on(001)MgO substrates by pulsed laser deposition.Microstructure studies with X-ray di®raction and transmission electron microscopy reveal that the as-grown Ba(Zr_(0.2)Ti_(0.8))O_(3) thin films are c-axis oriented with an atomic sharp interface.The films have good single crystallinity and good epitaxial quality.The interface relationship was determined to be[100]Mn.BZT//[100]MgO and(001)Mn.BZT//(001)MgO.Nanoscale order/disorder relaxor structures were found with nano-columnar structures.The microwave dielectric measurements(15-18GHz)indicate that the¯lms have excellent dielectric properties with large dielectric constant value,high tunability,and low dielectric loss,promising the development of room temperature tunable microwave elements.

A Bilinear Immersed Finite Volume Element Method for the Diffusion Equation with Discontinuous Coefficient

This paper is to present a finite volume element(FVE)method based on the bilinear immersed finite element(IFE)for solving the boundary value problems of the diffusion equation with a discontinuous coefficient(interface problem).This method possesses the usual FVE method’s local conservation property and can use a structured mesh or even the Cartesian mesh to solve a boundary value problem whose coefficient has discontinuity along piecewise smooth nontrivial curves.Numerical examples are provided to demonstrate features of this method.In particular,this method can produce a numerical solution to an interface problem with the usual O(h2)(in L2 norm)and O(h)(in H1 norm)convergence rates.