Understanding the factors that regulate the induction, quality, and longevity of antiviral T cell responses is essential for devising rational strategies to prevent or combat infections. In this ...study, we show that interleukin-21 (IL-21), likely produced by CD4⁺ T cells, directly influences the generation of polyfunctional CD8⁺ T cells and that the number of CD4⁺ T cells that produce IL-21 differs markedly between acute and chronic infections. IL-21 regulates the development of CD8⁺ T cell exhaustion and the ability to contain chronic lymphocytic choriomeningitis virus infection. Thus, IL-21 serves as a critical helper factor that shapes the functional quality of antiviral CD8⁺ T cells and is required for viral control.
Abstract
Gamma-ray bursts (GRBs) are fascinating events due to their panchromatic nature. Their afterglow emission is observed from sub-TeV energies to radio wavelengths. We investigate GRBs that ...present an optical plateau, leveraging on the resemblance with the X-ray plateau shown in many GRB light curves (LCs). We comprehensively analyze all published GRBs with known redshifts and optical plateau observed mostly by the Neil Gehrels Swift Observatory (Swift). We fit 267 optical LCs and show the existence of the plateau in 102 cases, which is the largest compilation so far of optical plateaus. For 56 Swift GRBs with optical and X-ray plateaus, we compare the rest-frame end time at both wavelengths (
,
), and conclude that the plateau is achromatic between
and
. We also confirm the existence of the two-dimensional relations between
and the optical luminosity at the end of the plateau emission, which resembles the same luminosity–time correlation in X-rays (Dainotti et al. 2013). The existence of this optical correlation has been demonstrated for the largest sample of optical plateaus in the literature to date. The squared scatter in this optical correlation is smallest for the subset of the Gold GRBs with a decrease in the scatter equivalent to 52.4% when compared to the scatter of the entire GRB sample.
We propose a novel scheme to generate the spin-orbit coupling for a condensate placed inside an optical cavity by using a standing wave and a traveling wave. It is shown that the interplay of the ...laser lights and the cavity gives rise to rich quantum phases. Our scheme also generates a large synthetic magnetic field for the dressed spin state, which may facilitate the study of the quantum Hall effect in ultracold atomic gases.
ABSTRACT
We use the NewHorizon simulation to study the redshift evolution of bar properties and fractions within galaxies in the stellar masses range M⋆ = 107.25–1011.4$\, \rm {M}_\odot$ over the ...redshift range of z = 0.25–1.3. We select disc galaxies using stellar kinematics as a proxy for galaxy morphology. We employ two different automated bar detection methods, coupled with visual inspection, resulting in observable bar fractions of fbar = 0.070$_{{-0.012}}^{{+0.018}}$ at z ∼ 1.3, decreasing to fbar = 0.011$_{{-0.003}}^{{+0.014}}$ at z ∼ 0.25. Only one galaxy is visually confirmed as strongly barred in our sample. This bar is hosted by the most massive disc and only survives from z = 1.3 down to z = 0.7. Such a low bar fraction, in particular amongst Milky Way-like progenitors, highlights a missing bars problem, shared by literally all cosmological simulations with spatial resolution <100 pc to date. The analysis of linear growth rates, rotation curves, and derived summary statistics of the stellar, gas and dark matter components suggest that galaxies with stellar masses below 109.5−1010$\, \rm {M}_\odot$ in NewHorizon appear to be too dominated by dark matter relative to stellar content to form a bar, while more massive galaxies typically have formed large bulges that prevent bar persistence at low redshift. This investigation confirms that the evolution of the bar fraction puts stringent constraints on the assembly history of baryons and dark matter on to galaxies.
We investigate how environment affects satellite galaxies using their location within the projected phase space of their host haloes from the Wang et al.'s group catalogue. Using the Yonsei Zoom-in ...Cluster Simulations, we derive zones of constant mean infall time \overline{T}_inf in projected phase space, and catalogue in which zone each observed galaxy falls. Within each zone, we compute the mean observed galaxy properties including specific star formation rate, luminosity-weighted age, stellar metallicity, and α/Fe abundance ratio. By comparing galaxies in different zones, we inspect how shifting the mean infall time from recent infallers (\overline{T}_inf < 3 Gyr) to ancient infallers (\overline{T}_{inf}> 5 Gyr) impacts galaxy properties at fixed stellar and halo mass. Ancient infallers are more quenched, and the impact of environmental quenching is visible down to low host masses (≤group masses). Meanwhile, the quenching of recent infallers is weakly dependent on host mass, indicating they have yet to respond strongly to their current environment. α/Fe and especially metallicity are less dependent on host mass, but show a dependence on \overline{T}_{inf}. We discuss these results in the context of longer exposure times for ancient infallers to environmental effects, which grow more efficient in hosts with a deeper potential well and a denser intracluster medium. We also compare our satellites with a control field sample, and find that even the most recent infallers (\overline{T}_{inf} < 2 Gyr) are more quenched than field galaxies, in particular for cluster mass hosts. This supports the role of pre-processing and/or faster quenching in satellites.
The effects of nitrogen and oxygen atomic co-functionalization of graphite felt (GF) by ammoxidation reactions for the positive and negative electrodes of vanadium redox flow battery (VRFB) are ...investigated. Ammoxidative surface reactions of the pristine-GF with NH3/O2 results in effective N and O co-doping dominantly with kinetically relevant N and O functional groups; pyrrolic-N, pyridinic-N, and hydroxyl with high site densities. The intrinsic rate measurements reveal that the N and O co-functionalized GF electrodes (referred to as N-GF) afford one to several orders magnitude higher VO2+/VO2+ and V2+/V3+ redox kinetics than the pristine-GF. Notably, the N and O co-functionalization gives rise to 2–3 folds greater reaction kinetics for both half-cell reactions than the conventional electrodes doped only with O functional groups (O-GF) at similar atomic contents. The high electrocatalytic properties of N-GF afford 4–6% greater voltage and energy efficiencies in VRFB than the conventional O-GF electrode at high current density (110 mA cm−2) with ∼38% higher initial charge-discharge capability owing to the significantly reduced overpotential. These results suggest the marked synergetic contributions of N and O co-functionalization of carbon electrode for facilitation of vanadium redox kinetics and the high effectiveness of the simple and scalable ammoxidation-based functionalization protocol.
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The anisotropic mechanical behavior of extruded AZ31 magnesium alloy is described in relation to the crystallographic texture. Specimens taken at 0°, 45° and 90° to the extrusion direction were ...uniaxially loaded in tension and compression, and the texture evolution was measured under load, using synchrotron radiation. The correlation between the initial texture, the mechanical anisotropy and the activation of different deformation modes was interpreted using the in situ texture measurements and viscoplastic self-consistent simulation results. The activity of the basal 〈
a〉 slip and the tensile twinning exert a significant effect on the mechanical anisotropy during tension, while the importance of the 〈
c
+
a〉 slip increases during compression.
The COVID-19 pandemic has exposed the many broken fragments of US health care and social service systems, reinforcing extant health and socioeconomic inequities faced by structurally marginalized ...immigrant communities. Throughout the pandemic, even during the most critical period of rising cases in different epicenters, immigrants continued to work in high-risk-exposure environments while simultaneously having less access to health care and economic relief and facing discrimination. We describe systemic factors that have adversely affected low-income immigrants, including limiting their work opportunities to essential jobs, living in substandard housing conditions that do not allow for social distancing or space to safely isolate from others in the household, and policies that discourage access to public resources that are available to them or that make resources completely inaccessible. We demonstrate that the current public health infrastructure has not improved health care access or linkages to necessary services, treatments, or culturally competent health care providers, and we provide suggestions for how the Public Health 3.0 framework could advance this. We recommend the following strategies to improve the Public Health 3.0 public health infrastructure and mitigate widening disparities: (1) address the social determinants of health, (2) broaden engagement with stakeholders across multiple sectors, and (3) develop appropriate tools and technologies. (
2021;111(S3):S224-S231. https://doi.org/10.2105/AJPH.2021.306433).
The exoskeleton of the lobster
Homarus americanus is a multiphase biological composite material which consists of an organic matrix (crystalline α-chitin fibers and various types of non-crystalline ...proteins) and minerals (mainly calcite). In this study we discuss experimental data about the mesoscopic structure and the crystallographic texture (orientation distribution) of the α-chitin–protein fiber network in this material. The synchrotron measurements reveal very strong crystallographic textures of the α-chitin. According to these data, a large fraction of the α-chitin lattice cells is arranged with their longest axis parallel to the normal of the surface of the exoskeleton. Additionally, a smaller fraction of the α-chitin cells is oriented with their longest axis perpendicular to the cuticle surface. These structural investigations reveal the pronounced role of crystallographic orientation distributions in mineralized biological composite materials which may be of relevance for an improved understanding of biological and bio-inspired nano-composites.
The underlying mechanisms that are responsible for the improved room-temperature ductility in Mg–Y alloys compared to pure Mg are investigated by transmission electron microscopy and density ...functional theory. Both methods show a significant decrease in the intrinsic stacking fault I1 energy (I1 SFE) with the addition of Y. The influence of the SFE on the relative activation of different competing deformation mechanisms (basal, prismatic, pyramidal slip) is discussed. From this analysis we suggest a key mechanism which explains the transition from primary basal slip in hexagonal close-packed Mg to basal plus pyramidal slip in solid solution Mg–Y alloys. This mechanism is characterized by enhanced nucleation of 〈c+a〉 dislocations where the intrinsic stacking fault I1 (ISF1) acts as heterogeneous source for 〈c+a〉 dislocations. Possible electronic and geometric reasons for the modification of the SFE by substitutional Y atoms are identified and discussed.
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