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A bstract We investigate the possibility of a (sizable) nonperturbative contribution to the charm parton distribution function (PDF) in a nucleon, theoretical issues arising in its interpretation, and its potential impact on LHC scattering processes. The “fitted charm” PDF obtained in various QCD analyses contains a process-dependent component that is partly traced to power-suppressed radiative contributions in DIS and is generally different at the LHC. We discuss separation of the universal component of the nonperturbative charm from the rest of the radiative contributions and estimate its magnitude in the CT14 global QCD analysis at the next-to-next-to leading order in the QCD coupling strength, including the latest experimental data from HERA and the Large Hadron Collider. Models for the nonperturbative charm PDF are examined as a function of the charm quark mass and other parameters. The prospects for testing these models in the associated production of a Z boson and a charm jet at the LHC are studied under realistic assumptions, including effects of the final-state parton showering.

A bstract An interesting class of models posits that the dark matter is a Majorana fermion which interacts with a quark together with a colored scalar mediator. Such a theory can be tested in direct detection experiments, through dark matter scattering with heavy nuclei, and at the LHC, via jets and missing energy signatures. Motivated by the fact that such theories have spin-independent interactions that vanish at tree level, we examine them at one loop (along with RGE improvement to resum large logs), and find that despite its occurrence at a higher order of perturbation theory, the spin-independent scattering searches typically impose the strongest constraints on the model parameter space. We further analyze the corresponding LHC constraints at one loop and find that it is important to take them into account when interpreting the implications of searches for jets plus missing momentum on this class of models, thus providing the corresponding complementary information for this class of models.

Fast radio bursts (FRBs) are millisecond-duration radio transients 1 , 2 of unknown origin. Two possible mechanisms that could generate extremely coherent emission from FRBs invoke neutron star magnetospheres 3 – 5 or relativistic shocks far from the central energy source 6 – 8 . Detailed polarization observations may help us to understand the emission mechanism. However, the available FRB polarization data have been perplexing, because they show a host of polarimetric properties, including either a constant polarization angle during each burst for some repeaters 9 , 10 or variable polarization angles in some other apparently one-off events 11 , 12 . Here we report observations of 15 bursts from FRB 180301 and find various polarization angle swings in seven of them. The diversity of the polarization angle features of these bursts is consistent with a magnetospheric origin of the radio emission, and disfavours the radiation models invoking relativistic shocks. Polarization observations of the fast radio burst FRB 180301 with the FAST radio telescope show diverse polarization angle swings, consistent with a magnetospheric origin of the emission.

We propose a new observable for the measurement of the forward–backward asymmetry (AFB) in Drell–Yan lepton production. At hadron colliders, the AFB distribution is sensitive to both the electroweak (EW) fundamental parameter sin2θW, the weak mixing angle, and the parton distribution functions (PDFs). Hence, the determination of sin2θW and the updating of PDFs by directly using the same AFB spectrum are strongly correlated. This correlation would introduce large bias or uncertainty into both precise measurements of EW and PDF sectors. In this article, we show that the sensitivity of AFB on sin2θW is dominated by its average value around the Z pole region, while the shape (or gradient) of the AFB spectrum is insensitive to sin2θW and contains important information on the PDF modeling. Accordingly, a new observable related to the gradient of the spectrum is introduced, and demonstrated to be able to significantly reduce the potential bias on the determination of sin2θW when updating the PDFs using the same AFB data.

A bstract Understanding how sea quarks behave inside a nucleon is one of the most important physics goals of the proposed Electron-Ion Collider in China (EicC), which is designed to have a 3.5 GeV polarized electron beam (80% polarization) colliding with a 20 GeV polarized proton beam (70% polarization) at instantaneous luminosity of 2 × 10 33 cm − 2 s − 1 . A specific topic at EicC is to understand the polarization of individual quarks inside a longitudinally polarized nucleon. The potential of various future EicC data, including the inclusive and semi-inclusive deep inelastic scattering data from both doubly polarized electron-proton and electron- 3 He collisions, to reduce the uncertainties of parton helicity distributions is explored at the next-to-leading order in QCD, using the Error PDF Updating Method Package ( e P ump ) which is based on the Hessian profiling method. We show that the semi-inclusive data are well able to provide good separation between flavour distributions, and to constrain their uncertainties in the x > 0 . 005 region, especially when electron- 3 He collisions, acting as effective electron-neutron collisions, are taken into account. To enable this study, we have generated a Hessian representation of the DSSV14 set of PDF replicas, named DSSV14H PDFs.

A bstract We present a detailed comparison of the most recent sets of NNLO PDFs from the ABM, CT, HERAPDF, MSTW and NNPDF collaborations. We compare parton distributions at low and high scales and parton luminosities relevant for LHC phenomenology. We study the PDF dependence of LHC benchmark inclusive cross sections and differential distributions for electroweak boson and jet production in the cases in which the experimental covariance matrix is available. We quantify the agreement between data and theory by computing the χ 2 for each data set with all the various PDFs. PDF comparisons are performed consistently for common values of the strong coupling. We also present a benchmark comparison of jet production at the LHC, comparing the results from various available codes and scale settings. Finally, we discuss the implications of the updated NNLO PDF sets for the combined PDF+ α s uncertainty in the gluon fusion Higgs production cross section.

PurposeTo evaluate the safety and efficacy of radiofrequency (RF) ablation of the basivertebral nerve (BVN) for the treatment of chronic low back pain (CLBP) in a Food and Drug Administration approved Investigational Device Exemption trial. The BVN has been shown to innervate endplate nociceptors which are thought to be a source of CLBP.MethodsA total of 225 patients diagnosed with CLBP were randomized to either a sham (78 patients) or treatment (147 patients) intervention. The mean age within the study was 47 years (range 25–69) and the mean baseline ODI was 42. All patients had Type I or Type II Modic changes of the treated vertebral bodies. Patients were evaluated preoperatively, and at 2 weeks, 6 weeks and 3, 6 and 12 months postoperatively. The primary endpoint was the comparative change in ODI from baseline to 3 months.ResultsAt 3 months, the average ODI in the treatment arm decreased 20.5 points, as compared to a 15.2 point decrease in the sham arm (p = 0.019, per-protocol population). A responder analysis based on ODI decrease ≥ 10 points showed that 75.6% of patients in the treatment arm as compared to 55.3% in the sham control arm exhibited a clinically meaningful improvement at 3 months.ConclusionPatients treated with RF ablation of the BVN for CLBP exhibited significantly greater improvement in ODI at 3 months and a higher responder rate than sham treated controls. BVN ablation represents a potential minimally invasive treatment for the relief of chronic low back pain.Graphical abstractThese slides can be retrieved under Electronic Supplementary Material.

Background and Objective COVID-19 led to an unprecedented reliance on virtual modalities to maintain care continuity for patients living with chronic pain. We examined whether there were disparities in virtual specialty pain care for racial-ethnic minority groups during COVID-19. Design and Participants This was a retrospective national cohort study with two comparison groups: primary care patients with chronic pain seen immediately prior to COVID-19 (3/1/19–2/29/20) ( N  = 1,649,053) and a cohort of patients seen in the year prior (3/1/18–2/28–19; n  = 1,536,954). Main Measures We assessed use of telehealth (telephone or video) specialty pain care, in-person care specialty pain care, and any specialty pain care for both groups at 6 months following cohort inclusion. We used quasi-Poisson regressions to test associations between patient race and ethnicity and receipt of care. Key Results Prior to COVID-19, there were Black-White (RR = 0.64, 95% CI [0.62, 0.67]) and Asian-White (RR = 0.63, 95% CI [0.54, 0.75]) disparities in telehealth use, and these lessened during COVID-19 (Black-White: RR = 0.75, 95% CI [0.73, 0.77], Asian-White: RR = 0.81, 95% CI [0.74, 0.89]) but did not disappear. Individuals identifying as American Indian/Alaska Native used telehealth less than White individuals during early COVID-19 (RR = 0.98, 95% CI [0.85, 1.13] to RR = 0.87, 95% CI [0.79, 0.96]). Hispanic/Latinx individuals were less likely than non-Hispanic/Latinx individuals to use telehealth prior to COVID-19 but more likely during early COVID-19 (RR = 0.70, 95% CI [0.66, 0.75] to RR = 1.06, 95% CI [1.02, 1.09]). Disparities in virtual pain care occurred over the backdrop of overall decreased specialty pain care during the early phase of the pandemic (raw decrease of n  = 17,481 specialty care encounters overall from pre-COVID to COVID-era), including increased disparities in any VA specialty pain care for Black (RR = 0.81, 95% CI [0.80, 0.83] to RR = 0.79, 95% CI [0.77, 0.80]) and Asian (RR = 0.91, 95% CI [0.86, 0.97] to RR = 0.88, 95% CI [0.82, 0.94]) individuals. Conclusions Disparities in virtual specialty pain care were smaller during the early phases of the COVID-19 pandemic than prior to the pandemic but did not disappear entirely, despite the rapid growth in telehealth. Targeted efforts to increase access to specialty pain care need to be concentrated among racial-ethnic minority groups.

The molecular determinants of gating and regulation of the calcium channel Orai1 by the ER Ca 2+ sensor STIM1 during store-operated calcium entry are now defined. Influx of Ca 2+ through store-operated Ca 2+ channels (SOCs) is a central component of receptor-evoked Ca 2+ signals 1 . Orai channels are SOCs 2 , 3 , 4 that are gated by STIM1, a Ca 2+ sensor located in the ER 5 , 6 but how it gates and regulates the Orai channels is unknown. Here, we report the molecular basis for gating of Orais by STIM1. All Orai channels are fully activated by the conserved STIM1 amino acid fragment 344–442, which we termed SOAR (the STIM1 Orai activating region). SOAR acts in combination with STIM1 (450–485) to regulate the strength of interaction with Orai1. Activation of Orai1 by SOAR recapitulates all the kinetic properties of Orai1 activation by STIM1. However, mutations of STIM1 within SOAR prevent activation of Orai1 but not co-clustering of STIM1 and Orai1 in response to Ca 2+ store depletion, indicating that STIM1–Orai1 co-clustering is not sufficient for Orai1 activation. An intact carboxy terminus α-helicial region of Orai is required for activation by SOAR. Deleting most of the Orai1 amino terminus impaired Orai1 activation by STIM1, but Orai1 Δ1–73 interacted with and was fully activated by SOAR. Accordingly, the characteristic inward rectification of Orai is mediated by an interaction between the polybasic STIM1 (672–685) and a Pro-rich region in the N terminus of Orai1. Hence, the essential properties of Orai1 function can be rationalized by interactions with discrete regions of STIM1.

In the knowledge reasoning filed, algorithms based on translation have achieved great results in recent years. However, when translation-based models fit multi-map attribute relations, different relations will compete for the same embedding vector. At the same time, many knowledge graphs can automatically extract new triples from the Internet now. This further reduces the frequency of occurrence of a single relation in the knowledge graph, which creates more difficulty for translation-based models. Thus, the TransE_rel model is proposed by relaxing the constraints on relation vectors in the low-dimensional space. This model focuses more on relation reasoning and, when combined with other models, can also be used for entity reasoning. We conduct relation prediction and entity prediction on benchmark dataset and one dataset extracted by ourselves. By comparing with recent work, experimental results show that our method has achieved better performance on two tasks especially on relation prediction.