886 research outputs found

    Search for the standard model Higgs boson in the H to ZZ to 2l 2nu channel in pp collisions at sqrt(s) = 7 TeV

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    A search for the standard model Higgs boson in the H to ZZ to 2l 2nu decay channel, where l = e or mu, in pp collisions at a center-of-mass energy of 7 TeV is presented. The data were collected at the LHC, with the CMS detector, and correspond to an integrated luminosity of 4.6 inverse femtobarns. No significant excess is observed above the background expectation, and upper limits are set on the Higgs boson production cross section. The presence of the standard model Higgs boson with a mass in the 270-440 GeV range is excluded at 95% confidence level.Comment: Submitted to JHE

    Performance of the CMS Cathode Strip Chambers with Cosmic Rays

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    The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device in the CMS endcaps. Their performance has been evaluated using data taken during a cosmic ray run in fall 2008. Measured noise levels are low, with the number of noisy channels well below 1%. Coordinate resolution was measured for all types of chambers, and fall in the range 47 microns to 243 microns. The efficiencies for local charged track triggers, for hit and for segments reconstruction were measured, and are above 99%. The timing resolution per layer is approximately 5 ns

    Performance and Operation of the CMS Electromagnetic Calorimeter

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    The operation and general performance of the CMS electromagnetic calorimeter using cosmic-ray muons are described. These muons were recorded after the closure of the CMS detector in late 2008. The calorimeter is made of lead tungstate crystals and the overall status of the 75848 channels corresponding to the barrel and endcap detectors is reported. The stability of crucial operational parameters, such as high voltage, temperature and electronic noise, is summarised and the performance of the light monitoring system is presented

    Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV

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    The performance of muon reconstruction, identification, and triggering in CMS has been studied using 40 inverse picobarns of data collected in pp collisions at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection criteria covering a wide range of physics analysis needs have been examined. For all considered selections, the efficiency to reconstruct and identify a muon with a transverse momentum pT larger than a few GeV is above 95% over the whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4, while the probability to misidentify a hadron as a muon is well below 1%. The efficiency to trigger on single muons with pT above a few GeV is higher than 90% over the full eta range, and typically substantially better. The overall momentum scale is measured to a precision of 0.2% with muons from Z decays. The transverse momentum resolution varies from 1% to 6% depending on pseudorapidity for muons with pT below 100 GeV and, using cosmic rays, it is shown to be better than 10% in the central region up to pT = 1 TeV. Observed distributions of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO

    Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV

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    The performance of muon reconstruction, identification, and triggering in CMS has been studied using 40 inverse picobarns of data collected in pp collisions at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection criteria covering a wide range of physics analysis needs have been examined. For all considered selections, the efficiency to reconstruct and identify a muon with a transverse momentum pT larger than a few GeV is above 95% over the whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4, while the probability to misidentify a hadron as a muon is well below 1%. The efficiency to trigger on single muons with pT above a few GeV is higher than 90% over the full eta range, and typically substantially better. The overall momentum scale is measured to a precision of 0.2% with muons from Z decays. The transverse momentum resolution varies from 1% to 6% depending on pseudorapidity for muons with pT below 100 GeV and, using cosmic rays, it is shown to be better than 10% in the central region up to pT = 1 TeV. Observed distributions of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO

    Bariatric surgery: evidence-based practical recommendations

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    [Resumen] La obesidad mórbida es, habitualmente, refractaria a los tratamientos convencionales, por lo que la modificación de hábitos dietéticos y de actividad física y/o el uso de fármacos consiguen pérdidas de peso parciales con habitual recuperación posterior. La cirugía bariátrica constituye una opción terapéutica para los casos de obesidad con elevado índice de masa corporal (IMC) asociada a comorbilidades, con buenos resultados a corto y largo plazo. El Grupo de Trabajo sobre Obesidad de la Sociedad Española de Endocrinología y Nutrición (GOSEEN) ha elaborado un documento con recomendaciones prácticas basadas en la evidencia para el tratamiento quirúrgico de la obesidad. La revisión se estructura en 3 partes. En la primera se definen los conceptos de obesidad y comorbilidades asociadas, los tratamientos médicos y sus resultados, las indicaciones y contraindicaciones para el tratamiento quirúrgico con los criterios de selección de los pacientes, el manejo pre y perioperatorio y la valoración de grupos especiales, como adolescentes y personas de edad avanzada. En la segunda parte se describen las distintas técnicas quirúrgicas, las vías de acceso y los resultados comparativos, las complicaciones tanto a corto como a largo plazo, la repercusión de la pérdida ponderal sobre las comorbilidades y los criterios para evaluar la efectividad de la cirugía. En la tercera parte se desarrolla el seguimiento postoperatorio, el control dietético en fases tempranas y más tardías tras la cirugía, y el calendario de control médico y analítico con la suplementación de los distintos macro y micronutrientes en función de la técnica quirúrgica empleada. Se incluye un apartado final sobre gestación y cirugía bariátrica, así como tablas y gráficos complementarios al texto desarrollado. La cirugía bariátrica sigue siendo un tratamiento discutido para la obesidad, pero los resultados en la corrección del exceso ponderal con mejoría en las patologías asociadas y en la calidad de vida confirman que puede ser el tratamiento de elección en pacientes seleccionados, con la técnica quirúrgica apropiada y con un correcto control pre y postoperatorio.[Abstract] Morbid obesity is usually refractory to conventional treatments. Consequently, weight that is lost by modifying diet and exercise and/or the use of drugs is usually later regained. Bariatric surgery constitutes a therapeutic option in obese patients with a high body mass index associated with comorbidities and achieves good results in both the short and the long term. The Obesity Working Group of the Spanish Society of Endocrinology and Nutrition has produced a document with practical, evidencebased recommendations for the surgical treatment of obesity. The review is structured in three parts. The first part defines the concepts of obesity and associated comorbidities, medical treatments, their results, and the indications and contraindications for surgical treatment, as well as the criteria for patient selection, pre- and perisurgical management, and assessment of special groups such as adolescents and the elderly. The second part discusses the different surgical techniques, approaches and comparative results, short- and long-term complications, the repercussions of weight loss on comorbidities, and the criteria for assessing the effectiveness of surgery. The third part discusses postsurgical follow-up, dietary control in the early and subsequent stages after surgery and the schedule for medical and laboratory follow-up, together with the different macro- and micronutrient supplements that should be used depending on the surgical technique employed. A final section is included on pregnancy and bariatric surgery, as well as tables and figures that complement the text. Although bariatric surgery continues to be a questionable treatment for obesity, the results correcting excess weight, with improvements in associated comorbidities and in quality of life, confirm that this option could be the treatment of choice in selected patients when the appropriate surgical technique and correct preand postoperative follow-up are employed

    An Investigation into the Determining Factors of Zoo Visitor Attendances in UK Zoos

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    The debate as to which animals are most beneficial to keep in zoos in terms of financial and conservative value is readily disputed; however, demographic factors have also been shown to relate to visitor numbers on an international level. The main aims of this research were: (1) To observe the distribution and location of zoos across the UK, (2) to develop a way of calculating zoo popularity in terms of the species kept within a collection and (3) to investigate the factors related to visitor numbers regarding admission costs, popularity of the collection in terms of the species kept and local demographic factors. Zoo visitor numbers were positively correlated with generated popularity ratings for zoos based on the species kept within a collection and admission prices (Pearson correlation: n = 34, r = 0.268, P = 0.126 and n = 34, r = −0.430, P = 0.011). Animal collections are aggregated around large cities and tourist regions, particularly coastal areas. No relationship between demographic variables and visitor numbers was found (Pearson correlation: n = 34, r = 0.268, P = 0.126), which suggests that the popularity of a zoo's collection relative to the types and numbers of species kept is more indicative of a collection's visitor numbers than its surrounding demographic figures. Zoos should incorporate generating high popularity scores as part of their collection planning strategies, to ensure that they thrive in the future, not only as tourist attractions but also as major conservation organizations

    Measurement of the t-channel single top quark production cross section in pp collisions at √s =7 TeV

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    Multi-messenger observations of a binary neutron star merger

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    On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta

    Localization and Broadband Follow-Up of the Gravitational-Wave Transient GW150914

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    A gravitational-wave (GW) transient was identified in data recorded by the Advanced Laser InterferometerGravitational-wave Observatory (LIGO) detectors on 2015 September 14. The event, initially designated G184098and later given the name GW150914, is described in detail elsewhere. By prior arrangement, preliminary estimatesof the time, significance, and sky location of the event were shared with 63 teams of observers covering radio,optical, near-infrared, X-ray, and gamma-ray wavelengths with ground- and space-based facilities. In this Letter wedescribe the low-latency analysis of the GW data and present the sky localization of the first observed compactbinary merger. We summarize the follow-up observations reported by 25 teams via private Gamma-rayCoordinates Network circulars, giving an overview of the participating facilities, the GW sky localizationcoverage, the timeline, and depth of the observations. As this event turned out to be a binary black hole merger,there is little expectation of a detectable electromagnetic (EM) signature. Nevertheless, this first broadbandcampaign to search for a counterpart of an Advanced LIGO source represents a milestone and highlights the broadcapabilities of the transient astronomy community and the observing strategies that have been developed to pursueneutron star binary merger events. Detailed investigations of the EM data and results of the EM follow-upcampaign are being disseminated in papers by the individual teams
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