2,340 research outputs found

    Tetralogy of Fallot: Imaging of common and uncommon associations by multidetector CT

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    AbstractPurposeTo demonstrate the superior role of multidetector computed tomography (MDCT) in delineation of the extracardiac vascular abnormalities including the pulmonary arterial tree, major aortopulmonary collateral arteries (MAPCAs), patent ductus arteriosus (PDA), and also the detection of the common and uncommon findings in Fallot Tetralogy cases for proper pre-surgical evaluation.Material and methodsA retrospective study of all multidetector CT images acquired to evaluate suspected cases of Tetralogy of Fallot sent by their respective referring physicians between April 2009 and August 2010. A total of 23 cases were included in this study. MDCT protocol, image analysis and calculations used in the diagnosis are explained in detail.ResultsDetailed explanation of the MDCT imaging findings in the 23 cases with Tetralogy of Fallot, as well as the common and uncommon associations of the disease, namely pulmonary atresia, MAPCAs, PDAs, atrial septal defects (ASDs), right sided aortic arch, and a few less common associations.ConclusionA customized approach to MDCT imaging improves the diagnostic accuracy and reduces unneeded prolongation of the study and sedation times. A careful preoperative perceptive of the complex cardiovascular anatomy in patients with Tetralogy of Fallot aids in exposing the patient to a directed and prepared surgical approach

    Efecto de la fertilización con potasio y de la aplicación foliar de zinc y fósforo en el rendimiento de aceite y proteína y en las propiedades del aceite de algodón

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    In maximizing the quantity and quality of a crop’s nutritional value in terms of fatty acids and protein, it is necessary to identify the constraints which may affect it and to devise methods of overcoming them through the use of inputs or changes in management practices. Field experiments were conducted during two successive seasons at the Agricultural Research Center, Giza, Egypt, on the cotton cultivar “Giza 86” (Gossypium barbadense L.) to study the effects of potassium fertilization (at 0.0 and 47.4 kg of K ha–1) and foliar application of zinc (at 0.0 and 57.6 g of Zn ha–1, two times, 70 and 85 days after planting, “during square initiation and boll setting stage”) and phosphorus (at 0.0, 576, 1152 and 1728 g of P ha–1, two times, 80 and 95 days after planting) on cottonseed. The application of potassium along with spraying plants with zinc and phosphorus caused  an increase in cottonseed yield ha–1, seed index, seed oil content, oil and protein yields ha–1, seed oil unsaponifiable matter and total unsaturated fatty acids (oleic and linoleic). However, those treatments resulted in a decrease in oil acid value, saponification value and total saturated fatty acids. The highest P concentration of 1728 g ha–1 gave the best values of cottonseed yield/ha, seed index, and seed oil and protein yields/ha and oil saponifiable matter.Para maximizar la cantidad y calidad del valor nutricional de una semilla en términos de ácidos grasos y proteínas es necesario identificar los factores que los afectan y proponer métodos que favorezcan los resultados deseados a través de cambios o mejoras en las prácticas utilizadas. Los experimentos se llevaron a cabo en dos campañas sucesivas en el Agricultural Research Center, Giza, Egipto, en el cultivo “Giza 86” (Gossypium barbadense L.) para estudiar los efectos de la fertilización con potasio (a 0.0 y 47.7 kg por ha) y las aplicaciones foliares de zinc (a 0.0 y 57.6 g por ha, dos veces, 70 y 85 días después de la plantación) y fósforo (a 0.0, 576, 1152, y 1728 g por ha, dos veces, 80 y 95 días después de la plantación). La aplicación del potasio junto con la pulverización de las plantas con zinc y fósforo causó un incremento en el rendimiento del algodón, el índice de semilla, el contenido graso, los rendimientos de aceite y proteína, el contenido de materia insaponificable en el aceite y el contenido total de ácidos grasos insaturados (oleico y linoleico). Por el contrario estos tratamientos disminuyeron el índice de acidez, el índice de saponificación y el contenido de ácidos grasos saturados. La mayor concentración de fósforo produjo los mejores rendimientos de algodón, de índice de semilla, de los rendimientos de aceite y proteína, y de materia insaponificable en el aceite

    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

    Measurement of the t t-bar production cross section in the dilepton channel in pp collisions at sqrt(s) = 7 TeV

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    The t t-bar production cross section (sigma[t t-bar]) is measured in proton-proton collisions at sqrt(s) = 7 TeV in data collected by the CMS experiment, corresponding to an integrated luminosity of 2.3 inverse femtobarns. The measurement is performed in events with two leptons (electrons or muons) in the final state, at least two jets identified as jets originating from b quarks, and the presence of an imbalance in transverse momentum. The measured value of sigma[t t-bar] for a top-quark mass of 172.5 GeV is 161.9 +/- 2.5 (stat.) +5.1/-5.0 (syst.) +/- 3.6(lumi.) pb, consistent with the prediction of the standard model.Comment: Replaced with published version. Included journal reference and DO

    Combined search for the quarks of a sequential fourth generation

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    Results are presented from a search for a fourth generation of quarks produced singly or in pairs in a data set corresponding to an integrated luminosity of 5 inverse femtobarns recorded by the CMS experiment at the LHC in 2011. A novel strategy has been developed for a combined search for quarks of the up and down type in decay channels with at least one isolated muon or electron. Limits on the mass of the fourth-generation quarks and the relevant Cabibbo-Kobayashi-Maskawa matrix elements are derived in the context of a simple extension of the standard model with a sequential fourth generation of fermions. The existence of mass-degenerate fourth-generation quarks with masses below 685 GeV is excluded at 95% confidence level for minimal off-diagonal mixing between the third- and the fourth-generation quarks. With a mass difference of 25 GeV between the quark masses, the obtained limit on the masses of the fourth-generation quarks shifts by about +/- 20 GeV. These results significantly reduce the allowed parameter space for a fourth generation of fermions.Comment: Replaced with published version. Added journal reference and DO

    Search for anomalous t t-bar production in the highly-boosted all-hadronic final state

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    A search is presented for a massive particle, generically referred to as a Z', decaying into a t t-bar pair. The search focuses on Z' resonances that are sufficiently massive to produce highly Lorentz-boosted top quarks, which yield collimated decay products that are partially or fully merged into single jets. The analysis uses new methods to analyze jet substructure, providing suppression of the non-top multijet backgrounds. The analysis is based on a data sample of proton-proton collisions at a center-of-mass energy of 7 TeV, corresponding to an integrated luminosity of 5 inverse femtobarns. Upper limits in the range of 1 pb are set on the product of the production cross section and branching fraction for a topcolor Z' modeled for several widths, as well as for a Randall--Sundrum Kaluza--Klein gluon. In addition, the results constrain any enhancement in t t-bar production beyond expectations of the standard model for t t-bar invariant masses larger than 1 TeV.Comment: Submitted to the Journal of High Energy Physics; this version includes a minor typo correction that will be submitted as an erratu

    Search for New Physics with Jets and Missing Transverse Momentum in pp collisions at sqrt(s) = 7 TeV

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    A search for new physics is presented based on an event signature of at least three jets accompanied by large missing transverse momentum, using a data sample corresponding to an integrated luminosity of 36 inverse picobarns collected in proton--proton collisions at sqrt(s)=7 TeV with the CMS detector at the LHC. No excess of events is observed above the expected standard model backgrounds, which are all estimated from the data. Exclusion limits are presented for the constrained minimal supersymmetric extension of the standard model. Cross section limits are also presented using simplified models with new particles decaying to an undetected particle and one or two jets

    X-ray emission from the Sombrero galaxy: discrete sources

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    We present a study of discrete X-ray sources in and around the bulge-dominated, massive Sa galaxy, Sombrero (M104), based on new and archival Chandra observations with a total exposure of ~200 ks. With a detection limit of L_X = 1E37 erg/s and a field of view covering a galactocentric radius of ~30 kpc (11.5 arcminute), 383 sources are detected. Cross-correlation with Spitler et al.'s catalogue of Sombrero globular clusters (GCs) identified from HST/ACS observations reveals 41 X-rays sources in GCs, presumably low-mass X-ray binaries (LMXBs). We quantify the differential luminosity functions (LFs) for both the detected GC and field LMXBs, whose power-low indices (~1.1 for the GC-LF and ~1.6 for field-LF) are consistent with previous studies for elliptical galaxies. With precise sky positions of the GCs without a detected X-ray source, we further quantify, through a fluctuation analysis, the GC LF at fainter luminosities down to 1E35 erg/s. The derived index rules out a faint-end slope flatter than 1.1 at a 2 sigma significance, contrary to recent findings in several elliptical galaxies and the bulge of M31. On the other hand, the 2-6 keV unresolved emission places a tight constraint on the field LF, implying a flattened index of ~1.0 below 1E37 erg/s. We also detect 101 sources in the halo of Sombrero. The presence of these sources cannot be interpreted as galactic LMXBs whose spatial distribution empirically follows the starlight. Their number is also higher than the expected number of cosmic AGNs (52+/-11 [1 sigma]) whose surface density is constrained by deep X-ray surveys. We suggest that either the cosmic X-ray background is unusually high in the direction of Sombrero, or a distinct population of X-ray sources is present in the halo of Sombrero.Comment: 11 figures, 5 tables, ApJ in pres

    Measurement of the Z/gamma* + b-jet cross section in pp collisions at 7 TeV

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    The production of b jets in association with a Z/gamma* boson is studied using proton-proton collisions delivered by the LHC at a centre-of-mass energy of 7 TeV and recorded by the CMS detector. The inclusive cross section for Z/gamma* + b-jet production is measured in a sample corresponding to an integrated luminosity of 2.2 inverse femtobarns. The Z/gamma* + b-jet cross section with Z/gamma* to ll (where ll = ee or mu mu) for events with the invariant mass 60 < M(ll) < 120 GeV, at least one b jet at the hadron level with pT > 25 GeV and abs(eta) < 2.1, and a separation between the leptons and the jets of Delta R > 0.5 is found to be 5.84 +/- 0.08 (stat.) +/- 0.72 (syst.) +(0.25)/-(0.55) (theory) pb. The kinematic properties of the events are also studied and found to be in agreement with the predictions made by the MadGraph event generator with the parton shower and the hadronisation performed by PYTHIA.Comment: Submitted to the Journal of High Energy Physic

    Search for supersymmetry in events with b-quark jets and missing transverse energy in pp collisions at 7 TeV

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    Results are presented from a search for physics beyond the standard model based on events with large missing transverse energy, at least three jets, and at least one, two, or three b-quark jets. The study is performed using a sample of proton-proton collision data collected at sqrt(s) = 7 TeV with the CMS detector at the LHC in 2011. The integrated luminosity of the sample is 4.98 inverse femtobarns. The observed number of events is found to be consistent with the standard model expectation, which is evaluated using control samples in the data. The results are used to constrain cross sections for the production of supersymmetric particles decaying to b-quark-enriched final states in the context of simplified model spectra.Comment: Submitted to Physical Review
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