A simple method for equine kinematic gait event detection

Background Previous studies have validated methods for determining kinematic gait events using threshold-based methods, however a simple method is yet to be identified that can be successfully applied to walk, trot and canter. Objectives To develop a simple kinematic method to identify the timing of hoof-on, peak vertical force and hoof-off, which can be applied to walk, trot and canter. Study design In-vivo method authentication study. Methods The horses (n = 3) were ridden in walk, trot and canter down a runway with four force plates arranged linearly. Three-dimensional forces were recorded at a sampling rate of 960 Hz and were synchronised with a ten-camera motion analysis system sampling at 120 Hz. Events identified from the vertical ground reaction force (GRFz) data were hoof-on (GRFz>50N), peak vertical force (GRFzpeak) and hoof-off (GRFz<50N). Kinematic identification of hoof-on and hoof-off events was based on sagittal planar angles of the fore and hindlimbs. Peak metacarpophalangeal/metatarsophalangeal (MCP/MTP) joint extension was used to assess the time of GRFzpeak. The accuracy (mean) and precision (s.d.) of the time difference between the kinetic and kinematic events were calculated for the fore and hindlimbs at each gait. Results Hoof-off was determined with better accuracy (range: -3.94 to 8.33 ms) and precision (5.43 to 11.39 ms) than hoof-on across all gaits. Peak MCP angle (5.83 to 19.65 ms) was a more precise representation of GRFzpeak than peak MTP angle (11.49 to 67.75 ms). Main limitations The sample size was small and, therefore, further validation is required. The proposed method was tested on one surface. Conclusions A simple kinematic method of detecting hoof-on, hoof-off and GRFzpeak is here proposed for walk, trot and canter. Further work should focus on validating the methodology in a larger number of horses and extending the method for use on surfaces with varying compliance

Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results

Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC

Measurements of inclusive jet suppression in heavy ion collisions at the LHC provide direct sensitivity to the physics of jet quenching. In a sample of lead-lead collisions at sqrt(s) = 2.76 TeV corresponding to an integrated luminosity of approximately 7 inverse microbarns, ATLAS has measured jets with a calorimeter over the pseudorapidity interval |eta| < 2.1 and over the transverse momentum range 38 < pT < 210 GeV. Jets were reconstructed using the anti-kt algorithm with values for the distance parameter that determines the nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of the jet yield is characterized by the jet "central-to-peripheral ratio," Rcp. Jet production is found to be suppressed by approximately a factor of two in the 10% most central collisions relative to peripheral collisions. Rcp varies smoothly with centrality as characterized by the number of participating nucleons. The observed suppression is only weakly dependent on jet radius and transverse momentum. These results provide the first direct measurement of inclusive jet suppression in heavy ion collisions and complement previous measurements of dijet transverse energy imbalance at the LHC.Comment: 15 pages plus author list (30 pages total), 8 figures, 2 tables, submitted to Physics Letters B. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2011-02

The performance of the jet trigger for the ATLAS detector during 2011 data taking

The performance of the jet trigger for the ATLAS detector at the LHC during the 2011 data taking period is described. During 2011 the LHC provided proton–proton collisions with a centre-of-mass energy of 7 TeV and heavy ion collisions with a 2.76 TeV per nucleon–nucleon collision energy. The ATLAS trigger is a three level system designed to reduce the rate of events from the 40 MHz nominal maximum bunch crossing rate to the approximate 400 Hz which can be written to offline storage. The ATLAS jet trigger is the primary means for the online selection of events containing jets. Events are accepted by the trigger if they contain one or more jets above some transverse energy threshold. During 2011 data taking the jet trigger was fully efficient for jets with transverse energy above 25 GeV for triggers seeded randomly at Level 1. For triggers which require a jet to be identified at each of the three trigger levels, full efficiency is reached for offline jets with transverse energy above 60 GeV. Jets reconstructed in the final trigger level and corresponding to offline jets with transverse energy greater than 60 GeV, are reconstructed with a resolution in transverse energy with respect to offline jets, of better than 4 % in the central region and better than 2.5 % in the forward direction

A search for resonances decaying into a Higgs boson and a new particle X in the XH → qqbb final state with the ATLAS detector

A search for heavy resonances decaying into a Higgs boson (H) and a new particle (X) is reported, utilizing 36.1 fb−1 of proton–proton collision data at collected during 2015 and 2016 with the ATLAS detector at the CERN Large Hadron Collider. The particle X is assumed to decay to a pair of light quarks, and the fully hadronic final state is analysed. The search considers the regime of high XH resonance masses, where the X and H bosons are both highly Lorentz-boosted and are each reconstructed using a single jet with large radius parameter. A two-dimensional phase space of XH mass versus X mass is scanned for evidence of a signal, over a range of XH resonance mass values between 1 TeV and 4 TeV, and for X particles with masses from 50 GeV to 1000 GeV. All search results are consistent with the expectations for the background due to Standard Model processes, and 95% CL upper limits are set, as a function of XH and X masses, on the production cross-section of the resonance

Measurement of the cross section for isolated-photon plus jet production in pp collisions at √s=13 TeV using the ATLAS detector

The dynamics of isolated-photon production in association with a jet in proton–proton collisions at a centre-of-mass energy of 13 TeV are studied with the ATLAS detector at the LHC using a dataset with an integrated luminosity of 3.2 fb−1. Photons are required to have transverse energies above 125 GeV. Jets are identified using the anti- algorithm with radius parameter and required to have transverse momenta above 100 GeV. Measurements of isolated-photon plus jet cross sections are presented as functions of the leading-photon transverse energy, the leading-jet transverse momentum, the azimuthal angular separation between the photon and the jet, the photon–jet invariant mass and the scattering angle in the photon–jet centre-of-mass system. Tree-level plus parton-shower predictions from Sherpa and Pythia as well as next-to-leading-order QCD predictions from Jetphox and Sherpa are compared to the measurements

Search for an invisibly decaying Higgs boson or dark matter candidates produced in association with a Z boson in pp collisions at root s=13 TeV with the ATLAS detector

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Carbohydrate metabolism and metabolic disorders in horses Metabolismo de carboidratos e disfunções metabólicas em equinos

Horses evolved consuming primarily fermentable forage carbohydrates, but forage diets have been traditionally supplemented with grain meals rich in starch and sugar in order to provide additional calories, protein and micronutrients. Starch and sugar are important for performance horses, but the consumption starch-rich meals may cause equine digestive and metabolic disorders. The critical capacity for preileal starch digestibility appears to be 0.35 to 0.4% but may be as little, depending on the source of starch. Small intestinal absorption of simple sugars is limited by the activity and expression of two classes of glucose carrier proteins, which are affected by chronic intake of hydrolyzable carbohydrate but may be sluggish to respond to abrupt changes in diet, further exacerbating the risk of overload. The most rapid fermentation occurs during starch overload or in the presence of fructans. Rapid fermentation perturbs the microbial and pH balance of the cecum and colon, favoring proliferation of Lactobacillus spp and acid production and increasing the risk of colic and laminitis. In addition to digestive disturbances, feeding grain concentrates rich in hydrolyzable carbohydrate may increase the risk of insulin resistance, which has been associated with obesity, laminitis and chronic founder, developmental orthopedic disease, and Cushing's disease in horses. This threshold concentration of starch intake may be a starting point for horse owners, feed manufacturers and veterinarians that may be claimed to be "low" enough to reduce risk in insulin resistant horses sensitive to grain-associated disorders.<br>Equinos desenvolvem-se consumindo primordialmente os carboidratos fermentáveis das forragens, porém as dietas a base de forragens vem sendo suplementadas com dietas a base de grãos, ricas em amido e açúcar, visando fornecer adicionais calorias, proteínas e micronutrientes. Amido e açucares são importantes para os equinos atletas, porém o consumo de dietas ricas em amido pode causar problemas digestivos e metabólicos aos equinos. A capacidade critica da digestão pré-ileal do amido varia entre 0,35 a 0,4%, podendo ser inferior, dependendo da fonte de amido. A absorção de açucares simples, no intestino delgado, depende da expressão de suas proteínas carreadoras de glicose, as quais são afetadas pela ingestão continua de carboidratos solúveis, porém podem ser mais vagarosas a responder a mudanças abruptas na dieta prevenindo o risco da sobrecarga. A fermentação mais rápida ocorre quando amido não digerido no intestino delgado adentra o intestino grosso e na presença de frutanas. A rápida fermentação perturba o equilíbrio da microbial e do pH de ceco e colon, favorecendo a proliferação de Lactobacillus spp e produção de ácido lático, aumentando o risco de cólicas e laminite. Adicionalmente aos distúrbios digestivos, dietas a base de grãos com alta concentração de carboidratos hidrolisáveis, pode aumentar o risco de resistência a insulina, a qual vem sendo associada com obesidade, laminite, distúrbios crônicos e desenvolvimento de problemas ortopédicos. O valor mínimo de ingestão de amido pode ser um ponto inicial na dieta de cavalos vencedores, processamento de alimentos e veterinários que podem estar recomendado a ser baixo o suficiente para reduzir o risco de resistência e insulina em equinos sensíveis a distúrbios associados a grãos