Racial disparities in chronic lymphocytic leukemia/small lymphocytic lymphoma accounting for small molecule inhibitors: A real-world cohort analysis

Kaplan-Meier curve depicting overall survival from CLL treatment start by race. For patients with CLL, no overall survival difference was observed between races in this real-world US database.

Study of High-Transverse-Momentum Higgs Boson Production in Association with a Vector Boson in the qqbb Final State with the ATLAS Detector

This Letter presents the first study of Higgs boson production in association with a vector boson (V=W or Z) in the fully hadronic qqbb final state using data recorded by the ATLAS detector at the LHC in proton-proton collisions at sqrt[s]=13  TeV and corresponding to an integrated luminosity of 137  fb^{-1}. The vector bosons and Higgs bosons are each reconstructed as large-radius jets and tagged using jet substructure techniques. Dedicated tagging algorithms exploiting b-tagging properties are used to identify jets consistent with Higgs bosons decaying into bb[over ¯]. Dominant backgrounds from multijet production are determined directly from the data, and a likelihood fit to the jet mass distribution of Higgs boson candidates is used to extract the number of signal events. The VH production cross section is measured inclusively and differentially in several ranges of Higgs boson transverse momentum: 250-450, 450-650, and greater than 650 GeV. The inclusive signal yield relative to the standard model expectation is observed to be μ=1.4_{-0.9}^{+1.0} and the corresponding cross section is 3.1±1.3(stat)_{-1.4}^{+1.8}(syst)  pb.

Measurement of the Centrality Dependence of the Dijet Yield in p+Pb Collisions at sqrt[s_{NN}]=8.16 TeV with the ATLAS Detector

ATLAS measured the centrality dependence of the dijet yield using 165  nb^{-1} of p+Pb data collected at sqrt[s_{NN}]=8.16  TeV in 2016. The event centrality, which reflects the p+Pb impact parameter, is characterized by the total transverse energy registered in the Pb-going side of the forward calorimeter. The central-to-peripheral ratio of the scaled dijet yields, R_{CP}, is evaluated, and the results are presented as a function of variables that reflect the kinematics of the initial hard parton scattering process. The R_{CP} shows a scaling with the Bjorken x of the parton originating from the proton, x_{p}, while no such trend is observed as a function of x_{Pb}. This analysis provides unique input to understanding the role of small proton spatial configurations in p+Pb collisions by covering parton momentum fractions from the valence region down to x_{p}∼10^{-3} and x_{Pb}∼4×10^{-4}.

Search for New Phenomena in Two-Body Invariant Mass Distributions Using Unsupervised Machine Learning for Anomaly Detection at sqrt[s]=13 TeV with the ATLAS Detector

Searches for new resonances are performed using an unsupervised anomaly-detection technique. Events with at least one electron or muon are selected from 140  fb^{-1} of pp collisions at sqrt[s]=13  TeV recorded by ATLAS at the Large Hadron Collider. The approach involves training an autoencoder on data, and subsequently defining anomalous regions based on the reconstruction loss of the decoder. Studies focus on nine invariant mass spectra that contain pairs of objects consisting of one light jet or b jet and either one lepton (e,μ), photon, or second light jet or b jet in the anomalous regions. No significant deviations from the background hypotheses are observed. Limits on contributions from generic Gaussian signals with various widths of the resonance mass are obtained for nine invariant masses in the anomalous regions.

Achievement of Target Gain Larger than Unity in an Inertial Fusion Experiment

On December 5, 2022, an indirect drive fusion implosion on the National Ignition Facility (NIF) achieved a target gain G_{target} of 1.5. This is the first laboratory demonstration of exceeding "scientific breakeven" (or G_{target}>1) where 2.05 MJ of 351 nm laser light produced 3.1 MJ of total fusion yield, a result which significantly exceeds the Lawson criterion for fusion ignition as reported in a previous NIF implosion [H. Abu-Shawareb et al. (Indirect Drive ICF Collaboration), Phys. Rev. Lett. 129, 075001 (2022)PRLTAO0031-900710.1103/PhysRevLett.129.075001]. This achievement is the culmination of more than five decades of research and gives proof that laboratory fusion, based on fundamental physics principles, is possible. This Letter reports on the target, laser, design, and experimental advancements that led to this result.

Observation of WZγ Production in pp Collisions at sqrt[s]=13 TeV with the ATLAS Detector

This Letter reports the observation of WZγ production and a measurement of its cross section using 140.1±1.2  fb^{-1} of proton-proton collision data recorded at a center-of-mass energy of 13 TeV by the ATLAS detector at the Large Hadron Collider. The WZγ production cross section, with both the W and Z bosons decaying leptonically, pp→WZγ→ℓ^{'}^{±}νℓ^{+}ℓ^{-}γ (ℓ^{(^{'})}=e, μ), is measured in a fiducial phase-space region defined such that the leptons and the photon have high transverse momentum and the photon is isolated. The cross section is found to be 2.01±0.30(stat)±0.16(syst)  fb. The corresponding standard model predicted cross section calculated at next-to-leading order in perturbative quantum chromodynamics and at leading order in the electroweak coupling constant is 1.50±0.06  fb. The observed significance of the WZγ signal is 6.3σ, compared with an expected significance of 5.0σ.

Burden of Illness in People with Alzheimer's Disease: A Systematic Review of Epidemiology, Comorbidities and Mortality

BACKGROUND

Alzheimer's disease (AD) is the most common neurodegenerative disease worldwide, and an updated quantification of its impact on morbidity, disability, and mortality is warranted. We conducted a systematic literature review, focusing on the past decade, to characterize AD and assess its impact on affected individuals.

METHODS

Searches of Embase, MEDLINE, and the Cochrane Library were conducted on August 7, 2020 and updated on November 10, 2021. Observational studies from any country reporting incidence, prevalence, comorbidities, and/or outcomes related to disability and mortality/life expectancy, in people with mild cognitive impairment (MCI) due to AD, or mild, moderate, or severe AD dementia, were considered relevant.

RESULTS

Data were extracted from 88 studies (46 incidence/prevalence; 44 comorbidities; 25 mortality-/disability-related outcomes), mostly from Europe, the USA, and Asia. AD dementia diagnosis was confirmed using biomarkers in only 6 studies. Estimated 5-year mortality in AD was 35%, and comorbidity prevalence estimates varied widely (hypertension: 30.2-73.9%; diabetes: 6.0-24.3%; stroke: 2.7-13.7%). Overall, people with AD dementia were more likely to have cardiovascular disease or diabetes than controls, and 5-year mortality in people with AD dementia was double that in the age- and year-matched general population (115.0 vs 60.6 per 1,000 person-years).

CONCLUSIONS

AD is associated with excess morbidity and mortality. Future longitudinal studies of population aging, incorporating biomarker assessment to confirm AD diagnoses, are needed to better characterize the course of MCI due to AD and AD dementia.

Combined Measurement of the Higgs Boson Mass from the H→γγ and H→ZZ^{*}→4ℓ Decay Channels with the ATLAS Detector Using sqrt[s]=7, 8, and 13 TeV pp Collision Data

A measurement of the mass of the Higgs boson combining the H→ZZ^{*}→4ℓ and H→γγ decay channels is presented. The result is based on 140  fb^{-1} of proton-proton collision data collected by the ATLAS detector during LHC run 2 at a center-of-mass energy of 13 TeV combined with the run 1 ATLAS mass measurement, performed at center-of-mass energies of 7 and 8 TeV, yielding a Higgs boson mass of 125.11±0.09(stat)±0.06(syst)=125.11±0.11  GeV. This corresponds to a 0.09% precision achieved on this fundamental parameter of the Standard Model of particle physics.

Search for Dark Photons in Rare Z Boson Decays with the ATLAS Detector

A search for events with a dark photon produced in association with a dark Higgs boson via rare decays of the standard model Z boson is presented, using 139  fb^{-1} of sqrt[s]=13  TeV proton-proton collision data recorded by the ATLAS detector at the Large Hadron Collider. The dark boson decays into a pair of dark photons, and at least two of the three dark photons must each decay into a pair of electrons or muons, resulting in at least two same-flavor opposite-charge lepton pairs in the final state. The data are found to be consistent with the background prediction, and upper limits are set on the dark photon's coupling to the dark Higgs boson times the kinetic mixing between the standard model photon and the dark photon, α_{D}ϵ^{2}, in the dark photon mass range of [5, 40] GeV except for the ϒ mass window [8.8, 11.1] GeV. This search explores new parameter space not previously excluded by other experiments.

Observation of Single-Top-Quark Production in Association with a Photon Using the ATLAS Detector

This Letter reports the observation of single top quarks produced together with a photon, which directly probes the electroweak coupling of the top quark. The analysis uses 139  fb^{-1} of 13 TeV proton-proton collision data collected with the ATLAS detector at the Large Hadron Collider. Requiring a photon with transverse momentum larger than 20 GeV and within the detector acceptance, the fiducial cross section is measured to be 688±23(stat) _{-71}^{+75}(syst)  fb, to be compared with the standard model prediction of 515_{-42}^{+36}  fb at next-to-leading order in QCD.

A British Society for Haematology Guideline: Diagnosis and management of thrombotic thrombocytopenic purpura and thrombotic microangiopathies

The objective of this guideline is to provide healthcare professionals with clear, up-to-date and practical guidance on the management of thrombotic thrombocytopenic purpura (TTP) and related thrombotic microangiopathies (TMAs), including complement-mediated haemolytic uraemic syndrome (CM HUS); these are defined by thrombocytopenia, microangiopathic haemolytic anaemia (MAHA) and small vessel thrombosis. Within England, all TTP cases should be managed within designated regional centres as per NHSE commissioning for highly specialised services.

Measurement of Suppression of Large-Radius Jets and Its Dependence on Substructure in Pb+Pb Collisions at sqrt[s_{NN}]=5.02 TeV with the ATLAS Detector

This letter presents a measurement of the nuclear modification factor of large-radius jets in sqrt[s_{NN}]=5.02  TeV Pb+Pb collisions by the ATLAS experiment. The measurement is performed using 1.72  nb^{-1} and 257  pb^{-1} of Pb+Pb and pp data, respectively. The large-radius jets are reconstructed with the anti-k_{t} algorithm using a radius parameter of R=1.0, by reclustering anti-k_{t} R=0.2 jets, and are measured over the transverse momentum (p_{T}) kinematic range of 158 Collapse

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Measurement of the Sensitivity of Two-Particle Correlations in pp Collisions to the Presence of Hard Scatterings

A key open question in the study of multiparticle production in high-energy pp collisions is the relationship between the "ridge"-i.e., the observed azimuthal correlations between particles in the underlying event that extend over all rapidities-and hard or semihard scattering processes. In particular, it is not known whether jets or their soft fragments are correlated with particles in the underlying event. To address this question, two-particle correlations are measured in pp collisions at sqrt[s]=13  TeV using data collected by the ATLAS experiment at the LHC, with an integrated luminosity of 15.8  pb^{-1}, in two different configurations. In the first case, charged particles associated with jets are excluded from the correlation analysis, while in the second case, correlations are measured between particles within jets and charged particles from the underlying event. Second-order flow coefficients, v_{2}, are presented as a function of event multiplicity and transverse momentum. These measurements show that excluding particles associated with jets does not affect the measured correlations. Moreover, particles associated with jets do not exhibit any significant azimuthal correlations with the underlying event, ruling out hard processes contributing to the ridge.

Observation of an Excess of Dicharmonium Events in the Four-Muon Final State with the ATLAS Detector

A search is made for potential ccc[over ¯]c[over ¯] tetraquarks decaying into a pair of charmonium states in the four muon final state using proton-proton collision data at sqrt[s]=13  TeV, corresponding to an integrated luminosity of 140  fb^{-1} recorded by the ATLAS experiment at LHC. Two decay channels, J/ψ+J/ψ→4μ and J/ψ+ψ(2S)→4μ, are studied. Backgrounds are estimated based on a hybrid approach involving Monte Carlo simulations and data-driven methods. Statistically significant excesses with respect to backgrounds dominated by the single parton scattering are seen in the di-J/ψ channel consistent with a narrow resonance at 6.9 GeV and a broader structure at lower mass. A statistically significant excess is also seen in the J/ψ+ψ(2S) channel. The fitted masses and decay widths of the structures are reported.

Observation of the γγ→ττ Process in Pb+Pb Collisions and Constraints on the τ-Lepton Anomalous Magnetic Moment with the ATLAS Detector

This Letter reports the observation of τ-lepton-pair production in ultraperipheral lead-lead collisions Pb+Pb→Pb(γγ→ττ)Pb and constraints on the τ-lepton anomalous magnetic moment a_{τ}. The dataset corresponds to an integrated luminosity of 1.44  nb^{-1} of LHC Pb+Pb collisions at sqrt[s_{NN}]=5.02  TeV recorded by the ATLAS experiment in 2018. Selected events contain one muon from a τ-lepton decay, an electron or charged-particle track(s) from the other τ-lepton decay, little additional central-detector activity, and no forward neutrons. The γγ→ττ process is observed in Pb+Pb collisions with a significance exceeding 5 standard deviations and a signal strength of μ_{ττ}=1.03_{-0.05}^{+0.06} assuming the standard model value for a_{τ}. To measure a_{τ}, a template fit to the muon transverse-momentum distribution from τ-lepton candidates is performed, using a dimuon (γγ→μμ) control sample to constrain systematic uncertainties. The observed 95% confidence-level interval for a_{τ} is -0.057 Collapse

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Validating the Perceived Active School Travel Enablers and Barriers - Child (PASTEB-C) questionnaire

OBJECTIVES

Presently, child-specific tools and instruments related to active school travel (AST) are lacking. This methodological shortcoming often contributes to suboptimal AST behaviour evaluations and intervention programming. The aim of this paper was to develop and validate a theoretically informed child-specific scale regarding multiple perceived barriers and enablers known to impact children's participation in AST.

STUDY DESIGN

Mixed methods.

METHODS

A mixed-methods and multistudy scale development approach featuring the application of social-ecological theory, a validation pilot study (n = 80), and test-retest study (n = 96) was conducted in collaboration with children in Ontario, Canada. In tandem with completing cognitive interviews and online surveys, multiple analyses, including a qualitative thematic analysis, along with weighted Cohen's kappa, Cronbach's alpha, and confirmatory factor analysis were undertaken.

RESULTS

Qualitative analyses of the developed tool addressed face validity concerns related to the response options and definitions of terms used. Following the reliability analyses of 40 items, two confirmatory factor analyses were run to assess the construct validation of perceived AST barriers and enablers, and resulted in the development of the 24-item Perceived Active School Travel Enablers and Barriers - Child (PASTEB-C) questionnaire.

CONCLUSION

The developed PASTEB-C questionnaire may be used to inform the programming and development of AST interventions, as well as conduct child-specific AST research.

Effectiveness of out-patient based acute heart failure care: a pilot randomised controlled trial

OBJECTIVES

Acute heart failure (AHF) hospitalisation is associated with 10% mortality. Outpatient based management (OPM) of AHF appeared effective in observational studies. We conducted a pilot randomised controlled trial (RCT) comparing OPM with standard inpatient care (IPM).

METHODS

We randomised patients with AHF, considered to need IV diuretic treatment for ≥2 days, to IPM or OPM. We recorded all-cause mortality, and the number of days alive and out-of-hospital (DAOH). Quality of life, mental well-being and Hope scores were assessed. Mean NHS cost savings and 95% central range (CR) were calculated from bootstrap analysis. Follow-up: 60 days.

RESULTS

Eleven patients were randomised to IPM and 13 to OPM. There was no statistically significant difference in all-cause mortality during the index episode (1/11 vs 0/13) and up to 60 days follow-up (2/11 vs 2/13) [p = .86]. The OPM group accrued more DAOH {47 [36,51] vs 59 [41,60], p = .13}. Two patients randomised to IPM (vs 6 OPM) were readmitted [p = .31]. Hope scores increased more with OPM within 30 days but dropped to lower levels than IPM by 60 days. More out-patients had increased total well-being scores by 60 days (p = .04). OPM was associated with mean cost savings of £2658 (95% CR 460-4857) per patient.

CONCLUSIONS

Patients with acute HF randomised to OPM accrued more days alive out of hospital (albeit not statistically significantly in this small pilot study). OPM is favoured by patients and carers and is associated with improved mental well-being and cost savings.

Strong Constraints on Jet Quenching in Centrality-Dependent p+Pb Collisions at 5.02 TeV from ATLAS

Jet quenching is the process of color-charged partons losing energy via interactions with quark-gluon plasma droplets created in heavy-ion collisions. The collective expansion of such droplets is well described by viscous hydrodynamics. Similar evidence of collectivity is consistently observed in smaller collision systems, including pp and p+Pb collisions. In contrast, while jet quenching is observed in Pb+Pb collisions, no evidence has been found in these small systems to date, raising fundamental questions about the nature of the system created in these collisions. The ATLAS experiment at the Large Hadron Collider has measured the yield of charged hadrons correlated with reconstructed jets in 0.36  nb^{-1} of p+Pb and 3.6  pb^{-1} of pp collisions at 5.02 TeV. The yields of charged hadrons with p_{T}^{ch}>0.5  GeV near and opposite in azimuth to jets with p_{T}^{jet}>30 or 60 GeV, and the ratios of these yields between p+Pb and pp collisions, I_{pPb}, are reported. The collision centrality of p+Pb events is categorized by the energy deposited by forward neutrons from the struck nucleus. The I_{pPb} values are consistent with unity within a few percent for hadrons with p_{T}^{ch}>4  GeV at all centralities. These data provide new, strong constraints that preclude almost any parton energy loss in central p+Pb collisions.

Search for Heavy Neutral Leptons in Decays of W Bosons Using a Dilepton Displaced Vertex in sqrt[s]=13 TeV pp Collisions with the ATLAS Detector

A search for a long-lived, heavy neutral lepton (N) in 139  fb^{-1} of sqrt[s]=13  TeV pp collision data collected by the ATLAS detector at the Large Hadron Collider is reported. The N is produced via W→Nμ or W→Ne and decays into two charged leptons and a neutrino, forming a displaced vertex. The N mass is used to discriminate between signal and background. No signal is observed, and limits are set on the squared mixing parameters of the N with the left-handed neutrino states for the N mass range 3  GeV Collapse

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Test of CP Invariance in Higgs Boson Vector-Boson-Fusion Production Using the H→γγ Channel with the ATLAS Detector

A test of CP invariance in Higgs boson production via vector-boson fusion has been performed in the H→γγ channel using 139  fb^{-1} of proton-proton collision data at sqrt[s]=13  TeV collected by the ATLAS detector at the LHC. The optimal observable method is used to probe the CP structure of interactions between the Higgs boson and electroweak gauge bosons, as described by an effective field theory. No sign of CP violation is observed in the data. Constraints are set on the parameters describing the strength of the CP-odd component in the coupling between the Higgs boson and the electroweak gauge bosons in two effective field theory bases: d[over ˜] in the HISZ basis and c_{HW[over ˜]} in the Warsaw basis. The results presented are the most stringent constraints on CP violation in the coupling between Higgs and weak bosons. The 95% C.L. constraint on d[over ˜] is derived for the first time and the 95% C.L. constraint on c_{HW[over ˜]} has been improved by a factor of 5 compared to the previous measurement.

Joint consensus statement on the vaccination of adult and paediatric haematopoietic stem cell transplant recipients: Prepared on behalf of the British society of blood and marrow transplantation and cellular therapy (BSBMTCT), the Children's cancer and Leukaemia Group (CCLG), and British Infection Association (BIA)

Haematopoietic stem cell transplant (HSCT) recipients have deficiencies in their adaptive immunity against vaccine preventable diseases. National and International guidance recommends that HSCT recipients are considered 'never vaccinated' and offered a comprehensive course of revaccination. This position statement aims to draw upon the current evidence base and existing guidelines, and align this with national vaccine availability and licensing considerations in order to recommend a pragmatic and standardised re-vaccination schedule for adult and paediatric HSCT recipients in the UK.

Cohort profile: the ESC EURObservational Research Programme Non-ST-segment elevation myocardial infraction (NSTEMI) Registry

AIMS

The European Society of Cardiology (ESC) EURObservational Research Programme (EORP) Non-ST-segment elevation myocardial infarction (NSTEMI) Registry aims to identify international patterns in NSTEMI management in clinical practice and outcomes against the 2015 ESC Guidelines for the management of acute coronary syndromes in patients presenting without ST-segment-elevation.

METHODS AND RESULTS

Consecutively hospitalised adult NSTEMI patients (n = 3620) were enrolled between 11 March 2019 and 6 March 2021, and individual patient data prospectively collected at 287 centres in 59 participating countries during a two-week enrolment period per centre. The registry collected data relating to baseline characteristics, major outcomes (in-hospital death, acute heart failure, cardiogenic shock, bleeding, stroke/transient ischaemic attack, and 30-day mortality) and guideline-recommended NSTEMI care interventions: electrocardiogram pre- or in-hospital, pre-hospitalization receipt of aspirin, echocardiography, coronary angiography, referral to cardiac rehabilitation, smoking cessation advice, dietary advice, and prescription on discharge of aspirin, P2Y12 inhibition, angiotensin converting enzyme inhibitor (ACEi)/angiotensin receptor blocker (ARB), beta-blocker, and statin.

CONCLUSION

The EORP NSTEMI Registry is an international, prospective registry of care and outcomes of patients treated for NSTEMI, which will provide unique insights into the contemporary management of hospitalised NSTEMI patients, compliance with ESC 2015 NSTEMI Guidelines, and identify potential barriers to optimal management of this common clinical presentation associated with significant morbidity and mortality.

Safety of maintaining elective and emergency surgery during the COVID-19 pandemic with the introduction of a Protected Elective Surgical Unit (PESU): A cross-specialty evaluation of 30-day outcomes in 9,925 patients undergoing surgery in a University Health Board

Background

The COVID-19 pandemic has caused unprecedented health care challenges mandating surgical service reconfiguration. Within our hospital, emergency and elective streams were separated and self-contained Protected Elective Surgical Units were developed to mitigate against infection-related morbidity. Aims of this study were to determine the risk of COVID-19 transmission and mortality and whether the development of Protected Elective Surgical Units can result in significant reduction in risk.

Methods

A retrospective observational study of consecutive patients from 18 specialties undergoing elective or emergency surgery under general, spinal, or epidural anaesthetic over a 12-month study period was undertaken. Primary outcome measures were 30-day postoperative COVID-19 transmission rate and mortality. Secondary adjusted analyses were performed to ascertain hospital and Protected Elective Surgical Unit transmission rates.

Results

Between 15 March 2020 and 14 March 2021, 9,925 patients underwent surgery: 6,464 (65.1%) elective, 5,116 (51.5%) female, and median age 57 (39–70). A total of 69.5% of all procedures were performed in Protected Elective Surgical Units. Overall, 30-day postoperative COVID-19 transmission was 2.8% (3.4% emergency vs 1.2% elective P < .001). Protected Elective Surgical Unit postoperative transmission was significantly lower than non–Protected Elective Surgical Unit (0.42% vs 3.2% P < .001), with an adjusted likely in-hospital Protected Elective Surgical Unit transmission of 0.04%. The 30-day all-cause mortality was 1.7% and was 14.6% in COVID-19–positive patients. COVID-19 infection, age > 70, male sex, American Society of Anesthesiologists grade > 2, and emergency surgery were all independently associated with mortality.

Conclusion

This study has demonstrated that Protected Elective Surgical Units can facilitate high-volume elective surgical services throughout peaks of the COVID-19 pandemic while minimising viral transmission and mortality. However, mortality risk associated with perioperative COVID-19 infection remains high.

The burden and pattern of comorbidities and its relation to mortality in frail vs non-frail patients with chronic heart failure

Background

Frailty is common in patients with chronic heart failure (CHF). Frail patients are at high risk of poor clinical outcomes which might be attributable to the presence of multiple comorbidities. The impact of comorbidities on mortality in frail patients with CHF is not well described.

Aim

To compare the burden and patterns of comorbidities in frail vs non-frail patients with CHF and their impact on mortality.

Methods

We studied consecutive patients attending a routine follow-up visit to a HF clinic. Frailty was assessed using the Clinical Frailty Scale (CFS); those with CFS&gt;4 were classified as frail. Patients were classified into 6 comorbidity groups including: metabolic (obesity, diabetes); respiratory; renal; cancer; neuropsychiatric (depression, dementia); and degenerative (falls, arthritis, fragility fractures). We investigated the relation between frailty, comorbidity groups and all-cause mortality in patients with CHF.

Results

Amongst 467 patients with CHF [67% male, median (IQR) age 76 (69–82) years, NTproBNP 1156 (469–2463) ng/L], 291 patients had HF with reduced ejection fraction (HFrEF, LVEF &lt;40%), and 176 had HF with preserved ejection fraction (HFpEF, LVEF ≥40%). Frailty was more common in HFpEF vs HFrEF (51 vs 40%). 64% of patients had &gt;4 comorbidities (36% 5–6, 21% 7–9 and 7% &gt;9 comorbidities).

Frail patients were more likely to have multiple comorbidities than non-frail patients (85% vs 48% with &gt;4 comorbidities, p&lt;0.001). The number of comorbidities increased with worsening frailty severity (Figure 1). Those with HFrEF were more like to suffer from cancer, whereas those with HFpEF were more likely to have neuropsychiatric, metabolic and degenerative comorbidities.

During a median follow up of 554 days, 82 (18%) patients died. Increasing number of comorbidities was associated with increasing mortality. (Figure 2) Patients who were frail with &gt;4 comorbidities had a 6-fold increased risk of mortality compared to those who were neither frail nor had multiple comorbidities [HR (95% CI) 6.6 (3.2–13.9), p&lt;0.001]. In a model adjusted for age, sex, logNTproBNP and NYHA class, amongst comorbidity groups, the presence of renal and neuropsychiatric comorbidities were independent predictors of higher mortality.

Conclusion

Frail patients with CHF have a high comorbidity burden. The co-existence of frailty and multiple comorbidities predisposes to higher risk of mortality. Future studies should investigate whether treatment focusing on comorbidities improve outcomes.

Funding Acknowledgement

Type of funding sources: None.

Microbiome and Neurotrauma: Emerging Innovations

The gut-brain axis plays an important role in bidirectional communication that exists and can be altered by injury. Neurotrauma provides acute alteration in the GI tract and alters autonomic function. In this focused review, we highlight what is known about GI disruption following neurotrauma. We then delve into how this affects recovery. Areas of innovation and emerging pre-clinical results are addressed. Finally, we address the link between neurotrauma induced GI dysfunction and progression to neurodegenerative disease states.

Lawson Criterion for Ignition Exceeded in an Inertial Fusion Experiment

For more than half a century, researchers around the world have been engaged in attempts to achieve fusion ignition as a proof of principle of various fusion concepts. Following the Lawson criterion, an ignited plasma is one where the fusion heating power is high enough to overcome all the physical processes that cool the fusion plasma, creating a positive thermodynamic feedback loop with rapidly increasing temperature. In inertially confined fusion, ignition is a state where the fusion plasma can begin "burn propagation" into surrounding cold fuel, enabling the possibility of high energy gain. While "scientific breakeven" (i.e., unity target gain) has not yet been achieved (here target gain is 0.72, 1.37 MJ of fusion for 1.92 MJ of laser energy), this Letter reports the first controlled fusion experiment, using laser indirect drive, on the National Ignition Facility to produce capsule gain (here 5.8) and reach ignition by nine different formulations of the Lawson criterion.

Observation of WWW Production in pp Collisions at sqrt[s]=13 TeV with the ATLAS Detector

This Letter reports the observation of WWW production and a measurement of its cross section using 139  fb^{-1} of proton-proton collision data recorded at a center-of-mass energy of 13 TeV by the ATLAS detector at the Large Hadron Collider. Events with two same-sign leptons (electrons or muons) and at least two jets, as well as events with three charged leptons, are selected. A multivariate technique is then used to discriminate between signal and background events. Events from WWW production are observed with a significance of 8.0 standard deviations, where the expectation is 5.4 standard deviations. The inclusive WWW production cross section is measured to be 820±100 (stat)±80 (syst)  fb, approximately 2.6 standard deviations from the predicted cross section of 511±18  fb calculated at next-to-leading-order QCD and leading-order electroweak accuracy.

Maternal hemodynamics and neonatal birth weight in pregnancies complicated by gestational diabetes: new insights from novel causal inference analysis modeling

OBJECTIVE

Normal pregnancy is characterized by significant changes in maternal hemodynamics that are associated with fetal growth. Pregnancies complicated by gestational diabetes mellitus (GDM) are associated with large-for-gestational age and macrosomia, but the relationship between maternal hemodynamic parameters and birth weight (BW) among women with GDM has not been established. Our objective was to investigate the influence of maternal hemodynamics on neonatal BW in healthy pregnancies and in those complicated by GDM.

METHODS

This was a prospective, cross-sectional case-control study of women aged ≥ 16 years with a singleton viable pregnancy, recruited between January 2016 and February 2021 at Leicester Royal Infirmary, Leicester, UK. GDM was defined as a fasting glucose level ≥ 5.3 mmol/L and/or serum glucose level ≥ 7.8 mmol/L, 2 h following a 75-g oral glucose load. We collected data on maternal characteristics and pregnancy outcome, including body mass index (BMI) at booking and BW centile adjusted for gestational age at delivery. Maternal hemodynamic parameters were assessed at 34-42 weeks' gestation using the Arteriograph® and bioreactance techniques. Graphical causal inference methodology was used to identify causal effects of the measured variables on neonatal BW centile.

RESULTS

Included in the analysis were 141 women with GDM and 136 normotensive non-diabetic pregnant controls. 62% of the women with GDM were managed pharmacologically, with metformin and/or insulin. Variables included in the final model were cardiac output (CO), mean arterial pressure (MAP), total peripheral resistance (TPR), aortic augmentation index (AIx), aortic pulse wave velocity (PWV) and BMI at booking. Among the controls, maternal BMI, CO and aortic PWV were significantly associated with neonatal BW. Each SD increase in booking BMI produced an increase of 8.4 BW centiles (P = 0.002), in CO produced an increase of 9.4 BW centiles (P = 0.008) and in aortic PWV produced an increase of 7.1 BW centiles (P = 0.017). We found no significant relationship between MAP, TPR or aortic AIx and neonatal BW. Maternal hemodynamics influenced neonatal BW among the women with GDM in a similar manner to that in the control group, but only the relationship between maternal BMI and neonatal BW reached statistical significance, with a 1-SD increase in BMI producing an increase of 6.1 BW centiles (P = 0.019).

CONCLUSIONS

Maternal BMI, CO and PWV were determinants of BW in our control group. The relationship between maternal hemodynamics and neonatal BW was similar between women with GDM and healthy controls. Our findings therefore suggest that fetal growth restriction in pregnancies complicated by GDM may indicate maternal cardiovascular dysfunction. © 2022 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

A detailed map of Higgs boson interactions by the ATLAS experiment ten years after the discovery

The standard model of particle physics1-4 describes the known fundamental particles and forces that make up our Universe, with the exception of gravity. One of the central features of the standard model is a field that permeates all of space and interacts with fundamental particles5-9. The quantum excitation of this field, known as the Higgs field, manifests itself as the Higgs boson, the only fundamental particle with no spin. In 2012, a particle with properties consistent with the Higgs boson of the standard model was observed by the ATLAS and CMS experiments at the Large Hadron Collider at CERN10,11. Since then, more than 30 times as many Higgs bosons have been recorded by the ATLAS experiment, enabling much more precise measurements and new tests of the theory. Here, on the basis of this larger dataset, we combine an unprecedented number of production and decay processes of the Higgs boson to scrutinize its interactions with elementary particles. Interactions with gluons, photons, and W and Z bosons-the carriers of the strong, electromagnetic and weak forces-are studied in detail. Interactions with three third-generation matter particles (bottom (b) and top (t) quarks, and tau leptons (τ)) are well measured and indications of interactions with a second-generation particle (muons, μ) are emerging. These tests reveal that the Higgs boson discovered ten years ago is remarkably consistent with the predictions of the theory and provide stringent constraints on many models of new phenomena beyond the standard model.

Evaluation of prognostic risk models for postoperative pulmonary complications in adult patients undergoing major abdominal surgery: a systematic review and international external validation cohort study

BACKGROUND

Stratifying risk of postoperative pulmonary complications after major abdominal surgery allows clinicians to modify risk through targeted interventions and enhanced monitoring. In this study, we aimed to identify and validate prognostic models against a new consensus definition of postoperative pulmonary complications.

METHODS

We did a systematic review and international external validation cohort study. The systematic review was done in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We searched MEDLINE and Embase on March 1, 2020, for articles published in English that reported on risk prediction models for postoperative pulmonary complications following abdominal surgery. External validation of existing models was done within a prospective international cohort study of adult patients (≥18 years) undergoing major abdominal surgery. Data were collected between Jan 1, 2019, and April 30, 2019, in the UK, Ireland, and Australia. Discriminative ability and prognostic accuracy summary statistics were compared between models for the 30-day postoperative pulmonary complication rate as defined by the Standardised Endpoints in Perioperative Medicine Core Outcome Measures in Perioperative and Anaesthetic Care (StEP-COMPAC). Model performance was compared using the area under the receiver operating characteristic curve (AUROCC).

FINDINGS

In total, we identified 2903 records from our literature search; of which, 2514 (86·6%) unique records were screened, 121 (4·8%) of 2514 full texts were assessed for eligibility, and 29 unique prognostic models were identified. Nine (31·0%) of 29 models had score development reported only, 19 (65·5%) had undergone internal validation, and only four (13·8%) had been externally validated. Data to validate six eligible models were collected in the international external validation cohort study. Data from 11 591 patients were available, with an overall postoperative pulmonary complication rate of 7·8% (n=903). None of the six models showed good discrimination (defined as AUROCC ≥0·70) for identifying postoperative pulmonary complications, with the Assess Respiratory Risk in Surgical Patients in Catalonia score showing the best discrimination (AUROCC 0·700 [95% CI 0·683-0·717]).

INTERPRETATION

In the pre-COVID-19 pandemic data, variability in the risk of pulmonary complications (StEP-COMPAC definition) following major abdominal surgery was poorly described by existing prognostication tools. To improve surgical safety during the COVID-19 pandemic recovery and beyond, novel risk stratification tools are required.

FUNDING

British Journal of Surgery Society.

O-161 Using pluripotent stem cells for in vitro gametogenesis

Human reproduction depends on the formation of germ cells, the cell lineage responsible for making gametes.  Gametes are the only cell types in the body capable of passing DNA from one generation to the next, therefore problems at any stage of germ cell development leading up to the formation of gametes can lead to reproductive challenges or even premature ovarian aging.  In humans, germ cell development begins soon after embryo implantation with the specification of primordial germ cells (PGCs) from peri-implantation progenitor cells.  Once PGC specification has finished, no other cell type in the body is capable of contributing to the germ cell lineage.  Therefore, failure to specify PGCs will lead to certain infertility.  In order to study PGC development, my laboratory animal models, stem cells and organoid technology.  The advantage of using laboratory animal model is that PGC specification development and differentiation can be studied in vivo. The disadvantage is that human-specific mechanisms of PGC specification can be overlooked when not using human cells in research.  To overcome this, my lab builds and uses stem cell models of peri-implantation human development in order to understand PGC specification as well as stem cell models to study in vitro gametogenesis.  In this lecture, I will discuss latest advances in stem cell technology to understand fertility and infertility as well as human embryology.

SGLT2 inhibitors in heart failure with preserved and reduced ejection fraction: a systematic review and meta-analysis

Funding Acknowledgements

Type of funding sources: None.

Background

Over the recent months, the scenery of the pharmacological treatment of heart failure has changed. Sodium-glucose co-transporter 2 inhibitors (SGLT2i) have become the protagonists, as trial after trial is revealing a prognostic benefit of their use for patients with heart failure (HF). While their clear advantage in heart failure with reduced ejection fraction (HFrEF) has resulted in the addition of SGLT2i in the most recent treatment guidelines 1, the magnitude of their impact in heart failure with preserved ejection fraction (HFpEF) is still debated. With the recent results of EMPEROR-Preserved trial shedding more light into this matter 2, concrete evidence is needed now more than ever to ascertain the role of SGLT2i in the management of HFpEF.

Aims

We performed a systematic review and meta-analysis to evaluate the role of SLGT2i in the management of patients with HF. More specifically, we performed a pre-specified subgroup analysis to assess the impact of this drug class in heart failure with reduced and preserved ejection fraction separately.

Methods

We conducted a systematic search of PubMed, Embase, Cochrane and Web of Science databases from inception to 15th of September. With the primary endpoint being hospitalisation for heart failure (HHF) or cardiovascular death (CVD), we identified 9,493 articles out of which 8 randomised controlled trials and 20,758 patients were included in the meta-analysis 2–9. The hazard ratios (HR) and 95% CI given in each study were used for the meta-analysis. A random-effects model with inverse-variance weights was used to combine the effect measures from all studies on a logarithmic scale. Statistical heterogeneity was assessed using the I² statistic. The statistical analyses were conducted using the Review Manager (RevMan) software (version 5.3. Copenhagen: The Nordic Cochrane Centre, The Cochrane Collaboration, 2014).

Results

The use of SGLT2i was associated with a significant reduction in HHF or CVD both for the patients with heart failure and EF&gt;40% (HR=0.78, 95%CI: 0.69, 0.87; I2 0%) and for the patients with heart failure and EF&lt;40% (HR=0.74, 95%CI: 0.68, 0.81; I2 0%), while for the total population SGLT2i reduced the risk of HHF or CV death by 25% (HR=0.75, 95%CI: 0.70, 0.81; I2 0%) (figure 1). Additionally, a prespecified subanalysis showed that in the specific cohort of patients with heart failure and EF&gt;50%, SGLT2i resulted in 23% lower risk of HHF or CV death (HR=0.77, 95%CI: 0.66, 0.91; I2 22%) (figure 2).

Conclusion

This meta-analysis provides robust evidence that SGLT2i appear to have a prognostic benefit across the spectrum of heart failure subgroups in terms of HHF or CV death. Further large-scale randomised trials examining the role of this drug class in the management of HFpEF would be extremely valuable and might transform the field of therapeutic strategies in this challenging clinical entity.

High-precision measurement of the W boson mass with the CDF II detector

The mass of the W boson, a mediator of the weak force between elementary particles, is tightly constrained by the symmetries of the standard model of particle physics. The Higgs boson was the last missing component of the model. After observation of the Higgs boson, a measurement of the W boson mass provides a stringent test of the model. We measure the W boson mass, M_W, using data corresponding to 8.8 inverse femtobarns of integrated luminosity collected in proton-antiproton collisions at a 1.96 tera-electron volt center-of-mass energy with the CDF II detector at the Fermilab Tevatron collider. A sample of approximately 4 million W boson candidates is used to obtain [Formula: see text], the precision of which exceeds that of all previous measurements combined (stat, statistical uncertainty; syst, systematic uncertainty; MeV, mega-electron volts; c, speed of light in a vacuum). This measurement is in significant tension with the standard model expectation.

276 Safety of Maintaining Elective and Emergency Surgery During the COVID-19 Pandemic with the Introduction of an Innovative Protected Elective Surgical Unit (PESU): A Cross-Specialty Evaluation of 30-Day Outcomes in 9925 Patients Undergoing Surgery in a University Health Board

Aim

High quality mobile health applications (mhealth apps) have the potential to enhance the prevention, diagnosis, and treatment of burns. The primary aim of this study was to evaluate whether the quality of mhealth apps for burns care is being adequately assessed. The secondary aim was to determine whether these apps meet UK regulatory standards.

Method

We searched AMED, BNI, CINAHL, Cochrane library, Embase, Emcare, Medline and PsychInfo to identify studies assessing mhealth app quality for burns. The PRISMA reporting guideline was adhered to. Two independent reviewers screened s to identify relevant studies. We analysed whether seven established domains of mhealth app quality were assessed: design, information/content, usability, functionality, ethical issues, security/privacy, and user-perceived value.

Results

Of the 28 included studies, none assessed all seven domains of quality. Design was assessed in 4/28 studies; information/content in 26/28 studies; usability in 12/28 studies; functionality in 10/28 studies; ethical issues were never assessed in any studies; security/privacy was not assessed; subjective assessment was made in 9/28 studies. 17/28 studies included apps that met the definition of ‘medical device’ according to MHRA guidance, yet only one app was appropriately certified with the UK Conformity Assessed (UKCA) mark.

Conclusions

The quality of mHealth apps for burns are not being adequately assessed. The majority of apps should be considered medical devices according to UK standards, but only one was appropriately certified. Regulatory bodies should support mhealth app developers, so as to improve quality control whilst simultaneously fostering innovation.

Combined angular and energy dispersive diffraction: optimized data acquisition, normalization and reduction

Combined angular and energy dispersive diffraction is particularly well suited to experiments at high pressures in large-volume presses, and to the study of liquid or amorphous systems. This work describes the data acquisition, correction and reduction approach developed at the PSICHE beamline of the SOLEIL synchrotron. The measured data were normalized for both the scattering volume and the effective incident energy spectrum. By optimizing the acquisition strategy, the measurement time and radiation dose are greatly reduced. The correction and reduction protocol outputs normalized scattering profiles that are suitable for pair distribution function or liquid structure analysis. These processes are demostrated with examples from a number of real experimental data sets.

Robust but weak winter atmospheric circulation response to future Arctic sea ice loss

The possibility that Arctic sea ice loss weakens mid-latitude westerlies, promoting more severe cold winters, has sparked more than a decade of scientific debate, with apparent support from observations but inconclusive modelling evidence. Here we show that sixteen models contributing to the Polar Amplification Model Intercomparison Project simulate a weakening of mid-latitude westerlies in response to projected Arctic sea ice loss. We develop an emergent constraint based on eddy feedback, which is 1.2 to 3 times too weak in the models, suggesting that the real-world weakening lies towards the higher end of the model simulations. Still, the modelled response to Arctic sea ice loss is weak: the North Atlantic Oscillation response is similar in magnitude and offsets the projected response to increased greenhouse gases, but would only account for around 10% of variations in individual years. We further find that relationships between Arctic sea ice and atmospheric circulation have weakened recently in observations and are no longer inconsistent with those in models.

Search for Lepton-Flavor Violation in Z-Boson Decays with τ Leptons with the ATLAS Detector

A search for lepton-flavor-violating Z→eτ and Z→μτ decays with pp collision data recorded by the ATLAS detector at the LHC is presented. This analysis uses 139  fb^{-1} of Run 2 pp collisions at sqrt[s]=13  TeV and is combined with the results of a similar ATLAS search in the final state in which the τ lepton decays hadronically, using the same data set as well as Run 1 data. The addition of leptonically decaying τ leptons significantly improves the sensitivity reach for Z→ℓτ decays. The Z→ℓτ branching fractions are constrained in this analysis to B(Z→eτ)<7.0×10^{-6} and B(Z→μτ)<7.2×10^{-6} at 95% confidence level. The combination with the previously published analyses sets the strongest constraints to date: B(Z→eτ)<5.0×10^{-6} and B(Z→μτ)<6.5×10^{-6} at 95% confidence level.

Multiplex Fragment analysis detects all COVID-19 variants of concern

Introduction/Objective

The majority of tracking methods have employed whole genome sequencing, which can be very expensive and time consuming. An alternative method has been to use genotyping of specific mutations to identify variants. However, tracking SARS-CoV-2 variants by targeted methods has been a moving target. Most methods only multiplex four targets per reaction, but we have multiplexed 8 targets in a single tube using fragment analysis.

Methods/Case Report

Fluorescently labeled primers targeted a combination of insertion/ deletion mutations and single nucleotide mutations. The PCR amplified products, amplicons, were separated by capillary electrophoresis. Primers were designed to detect changes in size indicative of insertion or deletion mutations including: ORF1A:Del3675_3677, S:Del69_70, S:Del144, S:Del157_158, S:Del242_244, ORF8:Del119_120, and ORF8:ins28269-28273. Allele-specific primers were designed to detect both the wild-type and mutated versions of S:N501Y, S:E484K, and S:L452R.

Residual nasopharyngeal and nasal specimens testing positive for SARS-CoV-2 by RT-PCR or isothermal amplification (IDnow) methods were selected from May 1- June 24, 2021. Variant analysis was performed by multiplex targeted PCR and whole genome sequencing in parallel on the same specimens to determine positive percent agreement.

Results (if a Case Study enter NA)

Variant analysis was performed on 250 specimens detecting each of the major variants of concern Alpha (B.1.1.7, U.K. origin, n= 108), Beta (B.1.351, South Africa origin, n=3), Gamma (P.1, Brazil origin, n=12), Delta (B.1.617.2, Indian origin, n=17), and Iota (B.1.526, New York, n=5). Some specimens with low viral load were detected by only PCR (n=18), only WGS (n=41), or neither (n=20). Overall positive percent agreement was 95% (163/171).

Conclusion

This adjustable method robustly and accurately identifies COVID-19 VOCs utilizing a platform amenable to multiple targets (20-40 targets ranging from 100-500b.p. across four fluorescent channels) using equipment commonly found in routine molecular pathology laboratories. Future directions include adjusting targets to detect new variants.

918 Nasal Packing Duration in The Management of Epistaxis: A Cohort Study

Aim

Nasal packing is one of the mainstays of inpatient treatment for epistaxis. However, no current guidelines exist on optimal duration of nasal packing. This paper seeks to determine the optimal duration of nasal packing in terms of re-bleeding.

Method

A retrospective cohort study was conducted on patients admitted over a two-year period. Data collected included re-bleeding events following pack removal, age, gender, site of epistaxis, hypertension, trauma and anticoagulation medication.

Results

The rate of re-bleeding increased with length of pack duration; over 12 hours was associated with greater re-bleeding rates (p = &lt;0.001) and continued to be statistically significant when controlling for co-founders (p = 0.01). Those packed over 24 hours were over five times more likely to re-bleed than those packed less than 12 hours (p = 0.01. OR 5.34).

Conclusions

A packing duration of less than 12 hours is associated with lower rates of re-bleeding. Admitting teams should therefore aim to ensure that patient pathways involve early pack removal.

1014 Assessment of Prostate Gland Volume Estimations Using MRI And TRUS Compared to Radical Prostatectomy Specimens

Introduction

The prostate volume is an essential criterion to calculate prostate specific antigen density (PSAD). When selecting patients for active surveillance (AS), in newly diagnosed low risk prostate cancer group or continuing AS in previously diagnosed cancer prostate, PSAD plays a major role. Estimation of the volume using digital rectal exam or PSA are inaccurate. This study aims to conduct a retrospective review to evaluate the accuracy of prostatic volume estimates in patients who had TRUS and MRI scans, comparing the obtained volumes to the reference standard which is the actual volume of radical prostatectomy specimen.

Method

Data was collected retrospectively for all patients who had robotic assisted radical prostatectomy (RRP) at the Royal Stoke Hospital between October 2015 and October 2018. Clinical information of TRUS and MRI prostate volumes were extracted from PACS and prostate specimen volume was collected from the histopathology report of RRP specimen.

Results

Pathological specimen prostate volume showed a positive relationship between MRI and TRUS prostate volume with a correlation efficient of 0.71 for MRI vs RRP specimen volume and 0.81 for TRUS vs RRP specimen volume. Mean TRUS volume underestimated prostate volume by 7.33cc and mean MRI volume underestimated prostate volume by 0.02cc

Conclusions

Although the study showed positive correlation between measuring prostate volume using MRI and TRUS as compared to RRP specimens, MRI showed a greater accuracy as compared to TRUS. We conclude that using MRI prostate volume gives more precise prostate volume estimate aiding appropriate therapeutic planning of patients with prostate cancer.

Search for New Phenomena in Final States with Two Leptons and One or No b-Tagged Jets at sqrt[s]=13 TeV Using the ATLAS Detector

A search for new phenomena is presented in final states with two leptons and one or no b-tagged jets. The event selection requires the two leptons to have opposite charge, the same flavor (electrons or muons), and a large invariant mass. The analysis is based on the full run-2 proton-proton collision dataset recorded at a center-of-mass energy of sqrt[s]=13  TeV by the ATLAS experiment at the LHC, corresponding to an integrated luminosity of 139  fb^{-1}. No significant deviation from the expected background is observed in the data. Inspired by the B-meson decay anomalies, a four-fermion contact interaction between two quarks (b, s) and two leptons (ee or μμ) is used as a benchmark signal model, which is characterized by the energy scale and coupling, Λ and g_{*}, respectively. Contact interactions with Λ/g_{*} lower than 2.0 (2.4) TeV are excluded for electrons (muons) at the 95% confidence level, still far below the value that is favored by the B-meson decay anomalies. Model-independent limits are set as a function of the minimum dilepton invariant mass, which allow the results to be reinterpreted in various signal scenarios.

Search for Displaced Leptons in sqrt[s]=13 TeV pp Collisions with the ATLAS Detector

A search for charged leptons with large impact parameters using 139  fb^{-1} of sqrt[s]=13  TeV pp collision data from the ATLAS detector at the LHC is presented, addressing a long-standing gap in coverage of possible new physics signatures. Results are consistent with the background prediction. This search provides unique sensitivity to long-lived scalar supersymmetric lepton partners (sleptons). For lifetimes of 0.1 ns, selectron, smuon, and stau masses up to 720, 680, and 340  GeV, respectively, are excluded at 95% confidence level, drastically improving on the previous best limits from LEP.

Longitudinal Flow Decorrelations in Xe+Xe Collisions at sqrt[s_{NN}]=5.44 TeV with the ATLAS Detector

The first measurement of longitudinal decorrelations of harmonic flow amplitudes v_{n} for n=2-4 in Xe+Xe collisions at sqrt[s_{NN}]=5.44  TeV is obtained using 3  μb^{-1} of data with the ATLAS detector at the LHC. The decorrelation signal for v_{3} and v_{4} is found to be nearly independent of collision centrality and transverse momentum (p_{T}) requirements on final-state particles, but for v_{2} a strong centrality and p_{T} dependence is seen. When compared with the results from Pb+Pb collisions at sqrt[s_{NN}]=5.02  TeV, the longitudinal decorrelation signal in midcentral Xe+Xe collisions is found to be larger for v_{2}, but smaller for v_{3}. Current hydrodynamic models reproduce the ratios of the v_{n} measured in Xe+Xe collisions to those in Pb+Pb collisions but fail to describe the magnitudes and trends of the ratios of longitudinal flow decorrelations between Xe+Xe and Pb+Pb. The results on the system-size dependence provide new insights and an important lever arm to separate effects of the longitudinal structure of the initial state from other early and late time effects in heavy-ion collisions.