Racial Differences in Retinopathy of Prematurity

PURPOSE

To delineate racial differences in the incidence and time course of ROP in a large cohort of premature infants.

METHODS

The secondary analysis of data from the two Postnatal Growth and ROP Studies (G-ROP-1 and G-ROP-2) that were collected in 41 hospitals in North America from 2006 to 2017. According to self-reported maternal race, premature infants were classified into 3 groups: White (N = 5580), Black (N = 3252), and Asian (N = 353). Incidence, severity, and time course of ROP; plus disease; and postnatal weight gain rate were compared among racial groups.

RESULTS

Black infants had significantly smaller BW (mean 1035 vs. 1131 vs.1144 grams, P < .001) and lower GA (28.2 vs. 28.6, vs. 29.1 weeks, P < .001) than White and Asian infants. However, Black infants had lower incidences of severe ROP (11.1% vs. 12.4% vs. 11.9%), ROP (42.1% vs. 43.2% vs. 30.6%), and plus disease (3.6% vs. 6.3%, vs. 5.9%) than White and Asian infants (BW and GA adjusted risk ratio for Black vs. White 0.69 for severe ROP, 0.83 for ROP, 0.44 for plus disease, all P < .0001). Mean daily-weight-gain on days of life 11-20 and 21-30 were similar across groups (P > .05), but lower in Black and Asian infants on days 31-40 (P < .001). There were no differences in the timing of severe ROP and ROP across racial groups.

CONCLUSIONS

Despite relatively lower GA, BW, and daily-weight-gain, Black preterm infants had lower incidences of ROP and plus disease than White preterm infants. The mechanisms for these differences require further investigation.

Characterization and quantification of adeno-associated virus capsid-loading states by multi-wavelength analytical ultracentrifugation with UltraScan

Aim: We present multi-wavelength (MW) analytical ultracentrifugation (AUC) methods offering superior accuracy for adeno-associated virus characterization and quantification. Methods: Experimental design guidelines are presented for MW sedimentation velocity and analytical buoyant density equilibrium AUC. Results: Our results were compared with dual-wavelength AUC, transmission electron microscopy and mass photometry. In contrast to dual-wavelength AUC, MW-AUC correctly quantifies adeno-associated virus capsid ratios and identifies contaminants. In contrast to transmission electron microscopy, partially filled capsids can also be detected and quantified. In contrast to mass photometry, first-principle results are obtained. Conclusion: Our study demonstrates the improved information provided by MW-AUC, highlighting the utility of several recently integrated UltraScan programs, and reinforces AUC as the gold-standard analysis for viral vectors.

An open-label, multicenter, phase 2 study of a food enriched with docosahexaenoic acid in adults with sickle cell disease

Sickle cell disease (SCD) induces red blood cell sickling, which causes debilitating symptoms including vaso-occlusion and inflammation. We investigated a food enriched with omega-3 fatty acids to determine its effect on certain factors: blood cell membrane fatty acid composition (including anti-inflammatory elements-docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA)-and the pro-inflammatory, arachidonic acid (AA)); the inflammation biomarker, C-reactive protein (CRP); and vaso-occlusive crisis (VOC) pain. Ten adults with SCD ingested the food, daily, for 28 days. Evaluated measures included blood cell membrane fatty acid ratios (AA vs omega-3 (DHA+EPA)), CRP (mg/L) levels, and Visual Analogue Scale (VAS) scores (a VOC assessment). The food was well tolerated and led to a statistically significant CRP reduction (39%). However, changes in omega-3 fatty acid ratios and VAS scores were not significant. Overall, while the omega-3-enriched food reduced inflammation, larger, blinded studies are needed to assess its effectiveness on other measures.

Embryonic and Early Postnatal Cranial Bone Volume and Tissue Mineral Density Values for C57BL/6J Laboratory Mice

Background

Laboratory mice are routinely used in craniofacial research based on the relatively close genetic relationship and conservation of developmental pathways between humans and mice. Since genetic perturbations and disease states may have localized effects, data from individual cranial bones are valuable for the interpretation of experimental assays. We employ high‐resolution microcomputed tomography to characterize cranial bones of C57BL/6J mice at embryonic day (E) 15.5 and E17.5, day of birth (P0), and postnatal day 7 (P7) and provide estimates of individual bone volume and tissue mineral density (TMD).

Results

Average volume and TMD values are reported for individual bones. Significant differences in volume and TMD during embryonic ages likely reflect early mineralization of cranial neural crest‐derived and intramembranously forming bones. Although bones of the face and vault had higher TMD values during embryonic ages, bones of the braincase floor had significantly higher TMD values by P7.

Conclusions

These ontogenetic data on cranial bone volume and TMD serve as a reference standard for future studies using mice bred on a C57BL/6J genetic background. Our findings also highlight the importance of differentiating “control” data from mice that are presented as “unaffected” littermates, particularly when carrying a single copy of a cre‐recombinase gene.

Higher average volume and density of cranial neural crest‐derived and intramembranously‐forming bones during embryonic development.

Higher average density in bones of the braincase floor during early postnatal development.

Ontogenetic data on cranial bone volume and TMD serve as a reference standard for mice bred on a C57BL/6J genetic background.

Association of Surgical Necrotizing Enterocolitis and its Timing with Retinopathy of Prematurity

OBJECTIVE

 The study aimed to determine the association of surgical necrotizing enterocolitis (NEC) and its timing, with the development and timing of retinopathy of prematurity (ROP).

STUDY DESIGN

 This was a secondary data analysis of 7,483 preterm infants from the Postnatal Growth and Retinopathy of Prematurity Study. Associations between infants with surgical NEC, early-onset surgical NEC (8-28 days), and late-onset surgical NEC (over 28 days) with ROP were evaluated by using multivariable logistic regression models, controlling for birth weight, gestational age, small for gestational age status, chronic lung disease, intraventricular hemorrhage, hydrocephalus, patent ductus arteriosus, and periventricular leukomalacia.

RESULTS

 Three hundred fifty-six (4.8%) infants had surgical NEC, with 56% having early surgical NEC. Infants with surgical NEC had a higher risk of any ROP and severe ROP (adjusted odds ratio [OR]: 2.7; 95% CI: 1.9-3.7) and 2.5 (95% CI: 1.9-3.3), respectively; p < 0.001) compared with infants without surgical NEC. Infants with early surgical NEC were at the highest risk of developing ROP and severe ROP (adjusted OR: 3.1 [95% CI: 2.1-4.8], and 3.3 [95% CI: 2.3-4.7] respectively, p < 0.001). Infants with late surgical NEC were also at increased risk of developing ROP and severe ROP (adjusted OR: 2.1 [95% CI: 1.3-3.4], and 1.9 [95% CI: 1.3-2.8] respectively, p < 0.001) compared with infants without surgical NEC.

CONCLUSION

 Infants with surgical NEC, especially early surgical NEC, are at higher risk of ROP and severe ROP.

KEY POINTS

· Infants with surgical NEC are at higher risk of ROP and severe ROP than those without surgical NEC.. · Increased ROP risk is seen in infants with both early- or later onset surgical NEC.. · Early-onset surgical NEC is associated with a higher ROP risk compared with later onset surgical NEC..

Abstract 2763: Effect of murine vendor on anti-tumor immune responses to non-ablative pulsed focused ultrasound

Non-ablative image guided pulsed focused ultrasound (pFUS) has shown promise in murine tumor models as an immunomodulatory strategy for altering tumor microenvironment (TME). However, studies to date have demonstrated efficacy only in murine models procured from a single vendor. To determine whether differences in inbred mice obtained from 3 vendors would alter tumor growth and TME, we evaluated temporal expression of cytokine, chemokine and trophic factor (CCTF), and immune cell profiles following non-ablative pFUS to murine B16 melanoma flank tumors established in C57BL/6J mice. B16 cells (106 cells) were subcutaneously, bilaterally implanted into C57BL/6J mice (n=6/group/time-point) obtained from 3 vendors [Jackson Laboratories (JAX; n=36), Charles River (CR; n=36), Taconic Biosciences (Tac; n=36)]. Ultrasound guided pFUS (VIFU 2000, Alpinion) was administered at 1 MHz, at 6 MPa PNP to 5 mm tumors. Entire tumor volume was sonicated point-by-point along a 2×2 mm matrix with 20 msec pulse length, 10% duty cycle and a 5 Hz pulse repetition frequency. On days 1, 3, and 5 post-pFUS, spleens (Sp), lymph nodes (LN) and tumors were evaluated by proteomic (CCTF) and flow cytometry (FC) analyses. pFUS treatment demonstrated variable, vendor-dependent effects on tumor growth, CCTF and immune cell profiles. CR B16 volumes showed significant reduction (p&lt;0.05; 2-way ANOVA) starting at day 2 through day 5, but not in JAX or Tac mice. Proteomic analyses revealed a similar trend wherein CR TME exhibited upregulation of pro-inflammatory cytokines (TNFα, IL-1β, IL-12p70) on days 1 and 3, and downregulation of anti-inflammatory cytokines (VEGF, IL-10) over 5 days. Comparatively, less robust expression of anti-tumoral cytokines were observed in Tac and JAX TME over 5 days. FC corroborated tumor growth and molecular analyses, showing significant tumor infiltration of helper and cytotoxic T cells (Th, Tcyt), M1 macrophages and dendritic cells (DC) on days 3 and 5, compared to untreated controls. Day 5 CR Sp also exhibited a pro-inflammatory profile with T cells, macrophages and DC. Tac and JAX tumor profiles over days 1, 3 and 5 were relatively unchanged by pFUS with major, anti-tumoral immunological activity restricted to draining LN on days 5 and 3 in Tac and JAX, respectively. Moreover, molecular and immune cell differences were observed in B16 tumors from control mice on days 1, 3 and 5. Collectively, B16 bearing CR mice exhibited a more pronounced anti-tumor response to pFUS, resulting in reduced tumor growth and pro-inflammatory CCTF and immune cell profiles as compared to B16 tumors in Tac and JAX mice. Despite using the same mouse strain, tumor type, and pFUS parameters, profound vendor-dependent variability was observed, suggestive of the possible role of inherent genetic disparities among C57BL/6J mice from different vendors. These results suggest that vendor choice may be critical in evaluating anti-tumor effects of pFUS.

Citation Format: Parwathy Chandran, Ruby Hutchison, Lauren Tomlinson, Gadi Cohen, Scott R. Burks, Joseph A. Frank. Effect of murine vendor on anti-tumor immune responses to non-ablative pulsed focused ultrasound [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2763.

11 Frailty and the Rate of Fractures in Patients Initiated on Antihypertensive Medication

Introduction

There is concern regarding adverse effects of antihypertensive treatment, including falls and subsequent fractures, especially hip fractures. As frailty is increasingly recognised as an important risk factor for adverse outcomes, we examined its relationship to fracture rates in older patients after starting antihypertensives.

Methods

Using the Clinical Practice Research Datalink (CPRD), we identified participants over 65-years old starting a first-line antihypertensive medication. Using deficits identified in CPRD we classified patient-level frailty as “Fit”, “Mild”, “Moderate” or “Severe” using the Electronic Frailty Index. We calculated the rate of fractures by frailty level and fracture site, and determined the rate ratio (RR) of first fracture by frailty level, adjusting for confounding, using multivariable poisson regression. We conducted sensitivity analyses to additionally adjust for ethnicity, deprivation, and bisphosphonate use.

Results

44% of participants were classified as mildly frail or greater, but frail participants experienced 58% of all fractures, and 63% of hip fractures. The whole cohort showed a crude rate of 14.1 fractures/1000 person-years, with 4.5 hip fractures/1000 person-years. In severe frailty, this rises to 51.0 fractures/1000 person-years, and 17.7 hip fractures/1000 person-years. After adjustment for confounding, increasing frailty was associated with greater rate of any fracture, reaching RR 2.85 (95% confidence interval 2.43–3.33) for severe frailty versus fit. Results were unchanged in sensitivity analyses.

Conclusions

Frailty and fracture are both common in older participants who start antihypertensive medications. Increasing frailty was positively associated with increased rates of fracture. Clinicians need awareness of this relationship to consider fracture risk assessment and prevention in these patients.

Association of Weight Gain Acceleration With Risk of Retinopathy of Prematurity

Importance

Early slow postnatal weight gain, a surrogate for low insulinlike growth factor 1 (IGF-1) levels, is predictive of retinopathy of prematurity (ROP). While low IGF-1 levels inhibit retinal vessel growth, a later rise theoretically activates vascular endothelial growth factor, causing neovascularization. Rate of rise of IGF-1 level is represented by weight gain acceleration (WGA) and may be used to evaluate risk of ROP.

Objective

To evaluate whether faster WGA during a later postnatal period is associated with a higher, rather than lower, risk of severe ROP.

Design, Setting, and Participants

This secondary analysis of data from the Postnatal Growth and Retinopathy of Prematurity (G-ROP) study included 6835 infants undergoing ROP examinations from 29 hospitals in North America from January 2006 to June 2012. Data were analyzed from September to December 2016.

Main Outcomes and Measures

Early weight gain rate (WGR) during 29 to 33 weeks' postmenstrual age and late WGA during 34 to 38 weeks' postmenstrual age were determined using linear regression of daily weight measurements and changes in daily weight measurements, respectively. The primary outcome was the association of late WGA with severe ROP.

Results

Of the 6835 included infants, the mean (SD) birth weight was 1086 (357) g, and the mean (SD) gestational age was 27.9 (2.5) weeks. Risk of severe ROP increased with increasing late WGA up to about the 80th percentile of WGA. After adjusting for birth weight and gestational age, among infants in the lowest early WGR tertile, there was no association of late WGA with severe ROP, and among infants in the moderate and highest early WGR tertiles, the moderate WGA tertiles had the highest risk of ROP (moderate early WGR tertile: adjusted odds ratio, 1.38; 95% CI, 0.98-1.94; highest early WGR tertile: adjusted odds ratio, 1.63; 95% CI, 1.02-2.60).

Conclusions and Relevance

Although much attention has been paid to the association of slow weight gain with ROP, the association may be more complex than appreciated. These findings suggest that low early WGR is associated with severe ROP regardless of subsequent WGA, but if early WGR is moderate or high, subsequent rapid rises in WGR are associated with increasing risk of severe ROP. If validated in additional cohorts, this finding may affect potential therapies, such as the timing of IGF-1 supplementation.

In vitro Liver Zonation of Primary Rat Hepatocytes

The ability of the liver to simultaneously carry out multiple functions is dependent on the metabolic heterogeneity of hepatocytes spatially located within a liver lobule spanning from the portal triad to the central vein. This complex zonal architecture of the liver, however, makes accurate in vitro modeling a challenge and often standard culture systems assume a homogenous model which may lead to inaccurate translatability of results. Here, we use a combination of mathematical modeling and experimental data to demonstrate a readily constructible in vitro flow system capable of liver zonation in primary rat hepatocytes. We show the differential expression of zonation markers, enhanced functionality when compared to standard static cultures and zone-specific metabolism and cell damage in the presence of paracetamol, a known zone-specific toxin. This type of advanced system provides a more in-depth and essential understanding of liver physiology and pathophysiology as well as the accurate evaluation of pharmacological interventions at a zone-specific level.

Erratum to: Measurement of the W boson polarisation in t t ¯ events from pp collisions at s = 8 TeV in the lepton + jets channel with ATLAS

[This corrects the article DOI: 10.1140/epjc/s10052-017-4819-4.].

Characterizing Adversity of Lysosomal Accumulation in Nonclinical Toxicity Studies: Results from the 5th ESTP International Expert Workshop

Lysosomes have a central role in cellular catabolism, trafficking, and processing of foreign particles. Accumulation of endogenous and exogenous materials in lysosomes represents a common finding in nonclinical toxicity studies. Histologically, these accumulations often lack distinctive features indicative of lysosomal or cellular dysfunction, making it difficult to consistently interpret and assign adverse dose levels. To help address this issue, the European Society of Toxicologic Pathology organized a workshop where representative types of lysosomal accumulation induced by pharmaceuticals and environmental chemicals were presented and discussed. The expert working group agreed that the diversity of lysosomal accumulations requires a case-by-case weight-of-evidence approach and outlined several factors to consider in the adversity assessment, including location and type of cell affected, lysosomal contents, severity of the accumulation, and related pathological effects as evidence of cellular or organ dysfunction. Lysosomal accumulations associated with cytotoxicity, inflammation, or fibrosis were generally considered to be adverse, while those found in isolation (without morphologic or functional consequences) were not. Workshop examples highlighted the importance of thoroughly characterizing the biological context of lysosomal effects, including mechanistic data and functional in vitro readouts if available. The information provided here should facilitate greater consistency and transparency in the interpretation of lysosomal effects.

Search for electroweak production of supersymmetric particles in final states with two or three leptons at s = 13 TeV with the ATLAS detector

A search for the electroweak production of charginos, neutralinos and sleptons decaying into final states involving two or three electrons or muons is presented. The analysis is based on 36.1 fb- 1 ofs = 13  TeV proton-proton collisions recorded by the ATLAS detector at the Large Hadron Collider. Several scenarios based on simplified models are considered. These include the associated production of the next-to-lightest neutralino and the lightest chargino, followed by their decays into final states with leptons and the lightest neutralino via either sleptons or Standard Model gauge bosons; direct production of chargino pairs, which in turn decay into leptons and the lightest neutralino via intermediate sleptons; and slepton pair production, where each slepton decays directly into the lightest neutralino and a lepton. No significant deviations from the Standard Model expectation are observed and stringent limits at 95% confidence level are placed on the masses of relevant supersymmetric particles in each of these scenarios. For a massless lightest neutralino, masses up to 580 GeV are excluded for the associated production of the next-to-lightest neutralino and the lightest chargino, assuming gauge-boson mediated decays, whereas for slepton-pair production masses up to 500 GeV are excluded assuming three generations of mass-degenerate sleptons.

Performance of missing transverse momentum reconstruction with the ATLAS detector using proton-proton collisions at s = 13 TeV

The performance of the missing transverse momentum ( E T miss ) reconstruction with the ATLAS detector is evaluated using data collected in proton-proton collisions at the LHC at a centre-of-mass energy of 13 TeV in 2015. To reconstruct E T miss , fully calibrated electrons, muons, photons, hadronically decaying τ -leptons , and jets reconstructed from calorimeter energy deposits and charged-particle tracks are used. These are combined with the soft hadronic activity measured by reconstructed charged-particle tracks not associated with the hard objects. Possible double counting of contributions from reconstructed charged-particle tracks from the inner detector, energy deposits in the calorimeter, and reconstructed muons from the muon spectrometer is avoided by applying a signal ambiguity resolution procedure which rejects already used signals when combining the various E T miss contributions. The individual terms as well as the overall reconstructed E T miss are evaluated with various performance metrics for scale (linearity), resolution, and sensitivity to the data-taking conditions. The method developed to determine the systematic uncertainties of the E T miss scale and resolution is discussed. Results are shown based on the full 2015 data sample corresponding to an integrated luminosity of 3.2 fb - 1 .

Measurement of the Soft-Drop Jet Mass in pp Collisions at sqrt[s]=13 TeV with the ATLAS Detector

Jet substructure observables have significantly extended the search program for physics beyond the standard model at the Large Hadron Collider. The state-of-the-art tools have been motivated by theoretical calculations, but there has never been a direct comparison between data and calculations of jet substructure observables that are accurate beyond leading-logarithm approximation. Such observables are significant not only for probing the collinear regime of QCD that is largely unexplored at a hadron collider, but also for improving the understanding of jet substructure properties that are used in many studies at the Large Hadron Collider. This Letter documents a measurement of the first jet substructure quantity at a hadron collider to be calculated at next-to-next-to-leading-logarithm accuracy. The normalized, differential cross section is measured as a function of log_{10}ρ^{2}, where ρ is the ratio of the soft-drop mass to the ungroomed jet transverse momentum. This quantity is measured in dijet events from 32.9  fb^{-1} of sqrt[s]=13  TeV proton-proton collisions recorded by the ATLAS detector. The data are unfolded to correct for detector effects and compared to precise QCD calculations and leading-logarithm particle-level Monte Carlo simulations.

Measurement of the inclusive and fiducial t t ¯ production cross-sections in the lepton+jets channel in pp collisions at s = 8 TeV with the ATLAS detector

The inclusive and fiducial t t ¯ production cross-sections are measured in the lepton+jets channel using 20.2 fb - 1 of proton-proton collision data at a centre-of-mass energy of 8 TeV recorded with the ATLAS detector at the LHC. Major systematic uncertainties due to the modelling of the jet energy scale and b-tagging efficiency are constrained by separating selected events into three disjoint regions. In order to reduce systematic uncertainties in the most important background, the W +\,jets process is modelled using Z + jets events in a data-driven approach. The inclusive t t ¯ cross-section is measured with a precision of 5.7% to beσ inc ( t t ¯ ) = 248.3 ± 0.7 ( stat . ) ± 13.4 ( syst . ) ± 4.7 ( lumi . ) pb , assuming a top-quark mass of 172.5 GeV. The result is in agreement with the Standard Model prediction. The cross-section is also measured in a phase space close to that of the selected data. The fiducial cross-section isσ fid ( t t ¯ ) = 48.8 ± 0.1 ( stat . ) ± 2.0 ( syst . ) ± 0.9 ( lumi . ) pb with a precision of 4.5%.

Search for a new heavy gauge-boson resonance decaying into a lepton and missing transverse momentum in 36 fb - 1 of pp collisions at s = 13 TeV with the ATLAS experiment

The results of a search for new heavy W ' bosons decaying to an electron or muon and a neutrino using proton-proton collision data at a centre-of-mass energy ofs = 13  TeV are presented. The dataset was collected in 2015 and 2016 by the ATLAS experiment at the Large Hadron Collider and corresponds to an integrated luminosity of 36.1 fb - 1 . As no excess of events above the Standard Model prediction is observed, the results are used to set upper limits on the W ' boson cross-section times branching ratio to an electron or muon and a neutrino as a function of the W ' mass. Assuming a W ' boson with the same couplings as the Standard Model W boson, W ' masses below 5.1 TeV are excluded at the 95% confidence level.

Search for a Structure in the B_{s}^{0}π^{±} Invariant Mass Spectrum with the ATLAS Experiment

A search for the narrow structure, X(5568), reported by the D0 Collaboration in the decay sequence X→B_{s}^{0}π^{±}, B_{s}^{0}→J/ψϕ, is presented. The analysis is based on a data sample recorded with the ATLAS detector at the LHC corresponding to 4.9  fb^{-1} of pp collisions at 7 TeV and 19.5  fb^{-1} at 8 TeV. No significant signal was found. Upper limits on the number of signal events, with properties corresponding to those reported by D0, and on the X production rate relative to B_{s}^{0} mesons, ρ_{X}, were determined at 95% confidence level. The results are N(X)<382 and ρ_{X}<0.015 for B_{s}^{0} mesons with transverse momenta above 10 GeV, and N(X)<356 and ρ_{X}<0.016 for transverse momenta above 15 GeV. Limits are also set for potential B_{s}^{0}π^{±} resonances in the mass range 5550 to 5700 MeV.

Search for heavy ZZ resonances in the ℓ + ℓ - ℓ + ℓ - and ℓ + ℓ - ν ν ¯ final states using proton-proton collisions at s = 13 TeV with the ATLAS detector

A search for heavy resonances decaying into a pair of Z bosons leading toℓ + ℓ - ℓ + ℓ - andℓ + ℓ - ν ν ¯ final states, where ℓ stands for either an electron or a muon, is presented. The search uses proton-proton collision data at a centre-of-mass energy of 13  TeV corresponding to an integrated luminosity of 36.1  fb - 1 collected with the ATLAS detector during 2015 and 2016 at the Large Hadron Collider. Different mass ranges for the hypothetical resonances are considered, depending on the final state and model. The different ranges span between 200 and 2000  GeV . The results are interpreted as upper limits on the production cross section of a spin-0 or spin-2 resonance. The upper limits for the spin-0 resonance are translated to exclusion contours in the context of Type-I and Type-II two-Higgs-doublet models, while those for the spin-2 resonance are used to constrain the Randall-Sundrum model with an extra dimension giving rise to spin-2 graviton excitations.

A search for pair-produced resonances in four-jet final states at s = 13 TeV with the ATLAS detector

A search for massive coloured resonances which are pair-produced and decay into two jets is presented. The analysis uses 36.7 fb- 1 of s = 13 TeV pp collision data recorded by the ATLAS experiment at the LHC in 2015 and 2016. No significant deviation from the background prediction is observed. Results are interpreted in a SUSY simplified model where the lightest supersymmetric particle is the top squark, t ~ , which decays promptly into two quarks through R-parity-violating couplings. Top squarks with masses in the range 100 GeV < m t ~ < 410   GeV are excluded at 95% confidence level. If the decay is into a b-quark and a light quark, a dedicated selection requiring two b-tags is used to exclude masses in the ranges 100 GeV < m t ~ < 470   GeV and 480 GeV < m t ~ < 610   GeV . Additional limits are set on the pair-production of massive colour-octet resonances.

Search for doubly charged Higgs boson production in multi-lepton final states with the ATLAS detector using proton-proton collisions at s = 13 TeV

A search for doubly charged Higgs bosons with pairs of prompt, isolated, highly energetic leptons with the same electric charge is presented. The search uses a proton-proton collision data sample at a centre-of-mass energy of 13 TeV corresponding to 36.1 fb - 1 of integrated luminosity recorded in 2015 and 2016 by the ATLAS detector at the LHC. This analysis focuses on the decaysH ± ± → e ± e ± ,H ± ± → e ± μ ± andH ± ± → μ ± μ ± , fitting the dilepton mass spectra in several exclusive signal regions. No significant evidence of a signal is observed and corresponding limits on the production cross-section and consequently a lower limit on m ( H ± ± ) are derived at 95% confidence level. Withℓ ± ℓ ± = e ± e ± / μ ± μ ± / e ± μ ± , the observed lower limit on the mass of a doubly charged Higgs boson only coupling to left-handed leptons varies from 770 to 870 GeV (850 GeV expected) for B ( H ± ± → ℓ ± ℓ ± ) = 100 % and both the expected and observed mass limits are above 450 GeV for B ( H ± ± → ℓ ± ℓ ± ) = 10 % and any combination of partial branching ratios.

Measurement of differential cross-sections of a single top quark produced in association with a W boson at s = 13 TeV with ATLAS

The differential cross-section for the production of a W boson in association with a top quark is measured for several particle-level observables. The measurements are performed using36.1 fb - 1 of pp collision data collected with the ATLAS detector at the LHC in 2015 and 2016. Differential cross-sections are measured in a fiducial phase space defined by the presence of two charged leptons and exactly one jet matched to a b-hadron, and are normalised with the fiducial cross-section. Results are found to be in good agreement with predictions from several Monte Carlo event generators.

Measurement of quarkonium production in proton-lead and proton-proton collisions at 5.02 TeV with the ATLAS detector

The modification of the production of J / ψ , ψ ( 2 S ) , and Υ ( n S ) ( n = 1 , 2 , 3 ) in p+Pb collisions with respect to their production in pp collisions has been studied. The p+Pb and pp datasets used in this paper correspond to integrated luminosities of 28 nb - 1 and 25 pb - 1 respectively, collected in 2013 and 2015 by the ATLAS detector at the LHC, both at a centre-of-mass energy per nucleon pair of 5.02 TeV. The quarkonium states are reconstructed in the dimuon decay channel. The yields of J / ψ and ψ ( 2 S ) are separated into prompt and non-prompt sources. The measured quarkonium differential cross sections are presented as a function of rapidity and transverse momentum, as is the nuclear modification factor, R p Pb for J / ψ and Υ ( n S ) . No significant modification of the J / ψ production is observed while Υ ( n S ) production is found to be suppressed at low transverse momentum in p+Pb collisions relative to pp collisions. The production of excited charmonium and bottomonium states is found to be suppressed relative to that of the ground states in central p+Pb collisions.

Measurement of τ polarisation in Z / γ ∗ → τ τ decays in proton-proton collisions at s = 8 TeV with the ATLAS detector

This paper presents a measurement of the polarisation of τ leptons produced in Z / γ ∗ → τ τ decays which is performed with a dataset of proton-proton collisions ats = 8 TeV, corresponding to an integrated luminosity of 20.2 fb- 1 recorded with the ATLAS detector at the LHC in 2012. The Z / γ ∗ → τ τ decays are reconstructed from a hadronically decaying τ lepton with a single charged particle in the final state, accompanied by a τ lepton that decays leptonically. The τ polarisation is inferred from the relative fraction of energy carried by charged and neutral hadrons in the hadronic τ decays. The polarisation is measured in a fiducial region that corresponds to the kinematic region accessible to this analysis. The τ polarisation extracted over the full phase space within the Z / γ ∗ mass range of 66 < m Z / γ ∗ < 116 GeV is found to beP τ = - 0.14 ± 0.02 ( stat ) ± 0.04 ( syst ) . It is in agreement with the Standard Model prediction ofP τ = - 0.1517 ± 0.0019 , which is obtained from the ALPGEN event generator interfaced with the PYTHIA 6 parton shower modelling and the TAUOLA τ decay library.

Search for the direct production of charginos and neutralinos in final states with tau leptons in s = 13 TeV pp collisions with the ATLAS detector

A search for the direct production of charginos and neutralinos in final states with at least two hadronically decaying tau leptons is presented. The analysis uses a dataset of pp collisions corresponding to an integrated luminosity of 36.1 fb- 1 , recorded with the ATLAS detector at the Large Hadron Collider at a centre-of-mass energy of 13 TeV. No significant deviation from the expected Standard Model background is observed. Limits are derived in scenarios of pair production and of and production in simplified models where the neutralinos and charginos decay solely via intermediate left-handed staus and tau sneutrinos, and the mass of theτ ~ L state is set to be halfway between the masses of the and the . Chargino masses up to 630 GeV are excluded at 95% confidence level in the scenario of direct production of for a massless . Common and masses up to 760 GeV are excluded in the case of production of and assuming a massless . Exclusion limits for additional benchmark scenarios with large and small mass-splitting between the and the are also studied by varying theτ ~ L mass between the masses of the and the .

Measurement of longitudinal flow decorrelations in Pb+Pb collisions at s NN = 2.76 and 5.02 TeV with the ATLAS detector

Measurements of longitudinal flow correlations are presented for charged particles in the pseudorapidity range | η | < 2.4 using 7 and 470 μ b - 1 of Pb+Pb collisions ats NN = 2.76 and 5.02 TeV, respectively, recorded by the ATLAS detector at the LHC. It is found that the correlation between the harmonic flow coefficients v n measured in two separated η intervals does not factorise into the product of single-particle coefficients, and this breaking of factorisation, or flow decorrelation, increases linearly with the η separation between the intervals. The flow decorrelation is stronger at 2.76 TeV than at 5.02 TeV. Higher-order moments of the correlations are also measured, and the corresponding linear coefficients for the k th -moment of the v n are found to be proportional to k for v 3 , but not for v 2 . The decorrelation effect is separated into contributions from the magnitude of v n and the event-plane orientation, each as a function of η . These two contributions are found to be comparable. The longitudinal flow correlations are also measured between v n of different order in n. The decorrelations of v 2 and v 3 are found to be independent of each other, while the decorrelations of v 4 and v 5 are found to be driven by the nonlinear contribution from v 2 2 andv 2 v 3 , respectively.

Direct top-quark decay width measurement in the t t ¯ lepton+jets channel at s = 8 TeV with the ATLAS experiment

This paper presents a direct measurement of the decay width of the top quark using t t ¯ events in the lepton+jets final state. The data sample was collected by the ATLAS detector at the LHC in proton-proton collisions at a centre-of-mass energy of 8 TeV and corresponds to an integrated luminosity of 20.2 fb- 1 . The decay width of the top quark is measured using a template fit to distributions of kinematic observables associated with the hadronically and semileptonically decaying top quarks. The result,Γ t = 1.76 ± 0.33 ( stat. ) - 0.68 + 0.79 ( syst. ) GeV for a top-quark mass of 172.5 GeV, is consistent with the prediction of the Standard Model.

Measurement of the W-boson mass in pp collisions at s = 7 TeV with the ATLAS detector

A measurement of the mass of the W boson is presented based on proton-proton collision data recorded in 2011 at a centre-of-mass energy of 7 TeV with the ATLAS detector at the LHC, and corresponding to 4.6 fb - 1 of integrated luminosity. The selected data sample consists of 7.8 × 10 6 candidates in the W → μ ν channel and 5.9 × 10 6 candidates in the W → e ν channel. The W-boson mass is obtained from template fits to the reconstructed distributions of the charged lepton transverse momentum and of the W boson transverse mass in the electron and muon decay channels, yielding m W = 80370 ± 7 ( stat. ) ± 11 ( exp. syst. ) ± 14 ( mod. syst. ) MeV = 80370 ± 19 MeV , where the first uncertainty is statistical, the second corresponds to the experimental systematic uncertainty, and the third to the physics-modelling systematic uncertainty. A measurement of the mass difference between the W + and W - bosons yields m W + - m W - = - 29 ± 28  MeV.

Measurement of the W-boson mass in pp collisions at s = 7 TeV with the ATLAS detector

A measurement of the mass of the W boson is presented based on proton-proton collision data recorded in 2011 at a centre-of-mass energy of 7 TeV with the ATLAS detector at the LHC, and corresponding to 4.6 fb - 1 of integrated luminosity. The selected data sample consists of 7.8 × 10 6 candidates in the W → μ ν channel and 5.9 × 10 6 candidates in the W → e ν channel. The W-boson mass is obtained from template fits to the reconstructed distributions of the charged lepton transverse momentum and of the W boson transverse mass in the electron and muon decay channels, yieldingm W = 80370 ± 7 ( stat. ) ± 11 ( exp. syst. ) ± 14 ( mod. syst. ) MeV = 80370 ± 19 MeV , where the first uncertainty is statistical, the second corresponds to the experimental systematic uncertainty, and the third to the physics-modelling systematic uncertainty. A measurement of the mass difference between the W + and W - bosons yieldsm W + - m W - = - 29 ± 28  MeV.

Search for new phenomena in high-mass final states with a photon and a jet from pp collisions at s = 13 TeV with the ATLAS detector

A search is performed for new phenomena in events having a photon with high transverse momentum and a jet collected in 36.7 fb - 1 of proton-proton collisions at a centre-of-mass energy of s = 13 TeV recorded with the ATLAS detector at the Large Hadron Collider. The invariant mass distribution of the leading photon and jet is examined to look for the resonant production of new particles or the presence of new high-mass states beyond the Standard Model. No significant deviation from the background-only hypothesis is observed and cross-section limits for generic Gaussian-shaped resonances are extracted. Excited quarks hypothesized in quark compositeness models and high-mass states predicted in quantum black hole models with extra dimensions are also examined in the analysis. The observed data exclude, at 95% confidence level, the mass range below 5.3 TeV for excited quarks and 7.1 TeV (4.4 TeV) for quantum black holes in the Arkani-Hamed-Dimopoulos-Dvali (Randall-Sundrum) model with six (one) extra dimensions.

Search for heavy resonances decaying into WW in the e ν μ ν final state in pp collisions at s = 13 TeV with the ATLAS detector

A search for neutral heavy resonances is performed in the W W → e ν μ ν decay channel using pp collision data corresponding to an integrated luminosity of 36.1 fb - 1 , collected at a centre-of-mass energy of 13TeV by the ATLAS detector at the Large Hadron Collider. No evidence of such heavy resonances is found. In the search for production via the quark-antiquark annihilation or gluon-gluon fusion process, upper limits onσ X × B ( X → W W ) as a function of the resonance mass are obtained in the mass range between 200GeV and up to 5TeV for various benchmark models: a Higgs-like scalar in different width scenarios, a two-Higgs-doublet model, a heavy vector triplet model, and a warped extra dimensions model. In the vector-boson fusion process, constraints are also obtained on these resonances, as well as on a Higgs boson in the Georgi-Machacek model and a heavy tensor particle coupling only to gauge bosons.

Search for dark matter produced in association with bottom or top quarks in s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive dark-matter particles produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and missing transverse momentum are considered. The analysis uses 36.1 fb - 1 of proton-proton collision data recorded by the ATLAS experiment ats = 13  TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are interpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour-neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross-section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour-charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV , mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements.

Search for direct top squark pair production in final states with two leptons in s = 13 TeV pp collisions with the ATLAS detector

The results of a search for direct pair production of top squarks in events with two opposite-charge leptons (electrons or muons) are reported, using 36.1 fb - 1 of integrated luminosity from proton-proton collisions ats = 13 TeV collected by the ATLAS detector at the Large Hadron Collider. To cover a range of mass differences between the top squark t ~ and lighter supersymmetric particles, four possible decay modes of the top squark are targeted with dedicated selections: the decayt ~ → b χ ~ 1 ± into a b-quark and the lightest chargino withχ ~ 1 ± → W χ ~ 1 0 , the decayt ~ → t χ ~ 1 0 into an on-shell top quark and the lightest neutralino, the three-body decayt ~ → b W χ ~ 1 0 and the four-body decayt ~ → b ℓ ν χ ~ 1 0 . No significant excess of events is observed above the Standard Model background for any selection, and limits on top squarks are set as a function of the t ~ andχ ~ 1 0 masses. The results exclude at 95% confidence level t ~ masses up to about 720 GeV, extending the exclusion region of supersymmetric parameter space covered by previous searches.

Determination of the strong coupling constant α s from transverse energy-energy correlations in multijet events at s = 8 TeV using the ATLAS detector

Measurements of transverse energy-energy correlations and their associated asymmetries in multi-jet events using the ATLAS detector at the LHC are presented. The data used correspond tos = 8 TeV proton-proton collisions with an integrated luminosity of 20.2fb - 1 . The results are presented in bins of the scalar sum of the transverse momenta of the two leading jets, unfolded to the particle level and compared to the predictions from Monte Carlo simulations. A comparison with next-to-leading-order perturbative QCD is also performed, showing excellent agreement within the uncertainties. From this comparison, the value of the strong coupling constant is extracted for different energy regimes, thus testing the running ofα s ( μ ) predicted in QCD up to scales over 1 TeV . A global fit to the transverse energy-energy correlation distributions yieldsα s ( m Z ) = 0.1162 ± 0.0011 (exp.) - 0.0070 + 0.0084 (theo.) , while a global fit to the asymmetry distributions yields a value ofα s ( m Z ) = 0.1196 ± 0.0013 (exp.) - 0.0045 + 0.0075 (theo.) .

Measurement of lepton differential distributions and the top quark mass in t t ¯ production in pp collisions at s = 8 TeV with the ATLAS detector

This paper presents single lepton and dilepton kinematic distributions measured in dileptonic t t ¯ events produced in 20.2 fb - 1 ofs = 8  TeV pp collisions recorded by the ATLAS experiment at the LHC. Both absolute and normalised differential cross-sections are measured, using events with an opposite-charge e μ pair and one or two b-tagged jets. The cross-sections are measured in a fiducial region corresponding to the detector acceptance for leptons, and are compared to the predictions from a variety of Monte Carlo event generators, as well as fixed-order QCD calculations, exploring the sensitivity of the cross-sections to the gluon parton distribution function. Some of the distributions are also sensitive to the top quark pole mass; a combined fit of NLO fixed-order predictions to all the measured distributions yields a top quark mass value ofm t pole = 173.2 ± 0.9 ± 0.8 ± 1.2  GeV, where the three uncertainties arise from data statistics, experimental systematics, and theoretical sources.

Measurement of detector-corrected observables sensitive to the anomalous production of events with jets and large missing transverse momentum in p p collisions at s = 13 TeV using the ATLAS detector

Observables sensitive to the anomalous production of events containing hadronic jets and missing momentum in the plane transverse to the proton beams at the Large Hadron Collider are presented. The observables are defined as a ratio of cross sections, for events containing jets and large missing transverse momentum to events containing jets and a pair of charged leptons from the decay of a Z / γ ∗ boson. This definition minimises experimental and theoretical systematic uncertainties in the measurements. This ratio is measured differentially with respect to a number of kinematic properties of the hadronic system in two phase-space regions; one inclusive single-jet region and one region sensitive to vector-boson-fusion topologies. The data are found to be in agreement with the Standard Model predictions and used to constrain a variety of theoretical models for dark-matter production, including simplified models, effective field theory models, and invisible decays of the Higgs boson. The measurements use 3.2 fb- 1 of proton-proton collision data recorded by the ATLAS experiment at a centre-of-mass energy of 13  TeV and are fully corrected for detector effects, meaning that the data can be used to constrain new-physics models beyond those shown in this paper.

Search for Heavy Higgs Bosons A/H Decaying to a Top Quark Pair in pp Collisions at sqrt[s]=8 TeV with the ATLAS Detector

A search for heavy pseudoscalar (A) and scalar (H) Higgs bosons decaying into a top quark pair (tt[over ¯]) has been performed with 20.3  fb^{-1} of proton-proton collision data collected by the ATLAS experiment at the Large Hadron Collider at a center-of-mass energy sqrt[s]=8  TeV. Interference effects between the signal process and standard model tt[over ¯] production, which are expected to distort the signal shape from a single peak to a peak-dip structure, are taken into account. No significant deviation from the standard model prediction is observed in the tt[over ¯] invariant mass spectrum in final states with an electron or muon, large missing transverse momentum, and at least four jets. The results are interpreted within the context of a type-II two-Higgs-doublet model. Exclusion limits on the signal strength are derived as a function of the mass m_{A/H} and the ratio of the vacuum expectation values of the two Higgs fields, tanβ, for m_{A/H}>500  GeV.

Search for Dark Matter Produced in Association with a Higgs Boson Decaying to bb[over ¯] Using 36 fb^{-1} of pp Collisions at sqrt[s]=13 TeV with the ATLAS Detector

Several extensions of the standard model predict associated production of dark-matter particles with a Higgs boson. Such processes are searched for in final states with missing transverse momentum and a Higgs boson decaying to a bb[over ¯] pair with the ATLAS detector using 36.1  fb^{-1} of pp collisions at a center-of-mass energy of 13 TeV at the LHC. The observed data are in agreement with the standard model predictions and limits are placed on the associated production of dark-matter particles and a Higgs boson.

Performance of the ATLAS track reconstruction algorithms in dense environments in LHC Run 2

With the increase in energy of the Large Hadron Collider to a centre-of-mass energy of 13 [Formula: see text] for Run 2, events with dense environments, such as in the cores of high-energy jets, became a focus for new physics searches as well as measurements of the Standard Model. These environments are characterized by charged-particle separations of the order of the tracking detectors sensor granularity. Basic track quantities are compared between 3.2 fb[Formula: see text] of data collected by the ATLAS experiment and simulation of proton-proton collisions producing high-transverse-momentum jets at a centre-of-mass energy of 13 [Formula: see text]. The impact of charged-particle separations and multiplicities on the track reconstruction performance is discussed. The track reconstruction efficiency in the cores of jets with transverse momenta between 200 and 1600 [Formula: see text] is quantified using a novel, data-driven, method. The method uses the energy loss, [Formula: see text], to identify pixel clusters originating from two charged particles. Of the charged particles creating these clusters, the measured fraction that fail to be reconstructed is [Formula: see text] and [Formula: see text] for jet transverse momenta of 200-400 [Formula: see text] and 1400-1600 [Formula: see text], respectively.

Dietary practices in propionic acidemia: A European survey

Background

The definitive dietary management of propionic acidaemia (PA) is unknown although natural protein restriction with adequate energy provision is of key importance.

Aim

To describe European dietary practices in the management of patients with PA prior to the publication of the European PA guidelines.

Methods

This was a cross-sectional survey consisting of 27 questions about the dietary practices in PA patients circulated to European IMD dietitians and health professionals in 2014.

Results

Information on protein restricted diets of 186 PA patients from 47 centres, representing 14 European countries was collected. Total protein intake [PA precursor-free L-amino acid supplements (PFAA) and natural protein] met WHO/FAO/UNU (2007) safe protein requirements for age in 36 centres (77%). PFAA were used to supplement natural protein intake in 81% (n = 38) of centres, providing a median of 44% (14–83%) of total protein requirement. Seventy-four per cent of patients were prescribed natural protein intakes below WHO/FAO/UNU (2007) safe levels in one or more of the following age groups: 0–6 m, 7–12 m, 1–10 y, 11–16 y and > 16 y. Sixty-three per cent (n = 117) of patients were tube fed (74% gastrostomy), but only 22% received nocturnal feeds.

Conclusions

There was high use of PFAA with intakes of natural protein commonly below WHO/FAO/UNU (2007) safe levels. Optimal dietary management can only be determined by longitudinal, multi-centre, prospective case controlled studies. The metabolic instability of PA and small patient cohorts in each centre ensure that this is a challenging undertaking.

Study of W W γ and W Z γ production in p p collisions at s = 8 TeV and search for anomalous quartic gauge couplings with the ATLAS experiment

This paper presents a study of W W γ and W Z γ triboson production using events from proton-proton collisions at a centre-of-mass energy ofs = 8 TeV recorded with the ATLAS detector at the LHC and corresponding to an integrated luminosity of 20.2 fb- 1 . The W W γ production cross-section is determined using a final state containing an electron, a muon, a photon, and neutrinos ( e ν μ ν γ ). Upper limits on the production cross-section of the e ν μ ν γ final state and the W W γ and W Z γ final states containing an electron or a muon, two jets, a photon, and a neutrino ( e ν j j γ or μ ν j j γ ) are also derived. The results are compared to the cross-sections predicted by the Standard Model at next-to-leading order in the strong-coupling constant. In addition, upper limits on the production cross-sections are derived in a fiducial region optimised for a search for new physics beyond the Standard Model. The results are interpreted in the context of anomalous quartic gauge couplings using an effective field theory. Confidence intervals at 95% confidence level are derived for the 14 coupling coefficients to which W W γ and W Z γ production are sensitive.

Identification and rejection of pile-up jets at high pseudorapidity with the ATLAS detector

The rejection of forward jets originating from additional proton-proton interactions (pile-up) is crucial for a variety of physics analyses at the LHC, including Standard Model measurements and searches for physics beyond the Standard Model. The identification of such jets is challenging due to the lack of track and vertex information in the pseudorapidity range | η | > 2.5 . This paper presents a novel strategy for forward pile-up jet tagging that exploits jet shapes and topological jet correlations in pile-up interactions. Measurements of the per-jet tagging efficiency are presented using a data set of 3.2 fb- 1 of proton-proton collisions at a centre-of-mass energy of 13TeV collected with the ATLAS detector. The fraction of pile-up jets rejected in the range 2.5 < | η | < 4.5 is estimated in simulated events with an average of 22 interactions per bunch-crossing. It increases with jet transverse momentum and, for jets with transverse momentum between 20 and 50 GeV, it ranges between 49% and 67% with an efficiency of 85% for selecting hard-scatter jets. A case study is performed in Higgs boson production via the vector-boson fusion process, showing that these techniques mitigate the background growth due to additional proton-proton interactions, thus enhancing the reach for such signatures.

Measurement of W W / W Z → ℓ ν q q ' production with the hadronically decaying boson reconstructed as one or two jets in pp collisions at s = 8 TeV with ATLAS, and constraints on anomalous gauge couplings

This paper presents a study of the production of WW or WZ boson pairs, with one W boson decaying to e ν or μ ν and one W or Z boson decaying hadronically. The analysis uses 20.2 fb - 1 ofs = 8 TeV pp collision data, collected by the ATLAS detector at the Large Hadron Collider. Cross-sections for WW / WZ production are measured in high- p T fiducial regions defined close to the experimental event selection. The cross-section is measured for the case where the hadronically decaying boson is reconstructed as two resolved jets, and the case where it is reconstructed as a single jet. The transverse momentum distribution of the hadronically decaying boson is used to search for new physics. Observations are consistent with the Standard Model predictions, and 95% confidence intervals are calculated for parameters describing anomalous triple gauge-boson couplings.