2,406 research outputs found

    Prognostic Value of D-Dimer and Markers of Coagulation for Stratification of Abdominal Aortic Aneurysm growth

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    Abdominal aortic aneurysm (AAA) is associated with high morbidity and mortality and is an established cause of unbalanced hemostasis. A number of hemostatic biomarkers have been associated with AAA; however, the utility of hemostatic biomarkers in AAA diagnosis and prognosis is unclear. The aim of the present study was to characterize the potential prognostic value of D-dimer and markers of altered hemostasis in a large cohort of patients with AAAs characterized by either fast or slow aneurysm growth (frequency matched for baseline diameter) and subaneurysmal dilations. We measured plasma concentrations of thrombin-antithrombin (TAT) complex, platelet factor 4 (PF4), and D-dimer in 352 patients with either fast-growing AAAs (.2 mm/y), slow-growing AAAs (,2 mm/y), subaneurysmal aortic dilations, or nonaneurysmal aortas. Plasma D-dimer and TAT were significantly elevated in both AAA and subaneurysmal dilation patients compared with controls. Individuals with D-dimer levels $500 ng/mL had 3.09 times the odds of subaneurysms, 6.23 times the odds of slow-growing AAAs, and 7.19 times the odds of fast-growing AAAs than individuals with D-dimer level,500 ng/mL. However, no differences in D-dimer concentration were noted between fast- and slow-growing aneurysms. Plasma D-dimer and TAT were strong independent predictors of AAA growth rate with multivariate analysis revealing a 500-ng/mL increase in D-dimer or 1-mg/mL increase in TAT led to additional 0.21-mm and 0.24-mm changes in aortic diameter per year, respectively. Rising levels of plasma TAT, in addition to D-dimer, may predict disease progression and aneurysm growth in patients with AAA or subaneurysmal dilation

    Optimal control theory for unitary transformations

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    The dynamics of a quantum system driven by an external field is well described by a unitary transformation generated by a time dependent Hamiltonian. The inverse problem of finding the field that generates a specific unitary transformation is the subject of study. The unitary transformation which can represent an algorithm in a quantum computation is imposed on a subset of quantum states embedded in a larger Hilbert space. Optimal control theory (OCT) is used to solve the inversion problem irrespective of the initial input state. A unified formalism, based on the Krotov method is developed leading to a new scheme. The schemes are compared for the inversion of a two-qubit Fourier transform using as registers the vibrational levels of the X1Σg+X^1\Sigma^+_g electronic state of Na2_2. Raman-like transitions through the A1Σu+A^1\Sigma^+_u electronic state induce the transitions. Light fields are found that are able to implement the Fourier transform within a picosecond time scale. Such fields can be obtained by pulse-shaping techniques of a femtosecond pulse. Out of the schemes studied the square modulus scheme converges fastest. A study of the implementation of the QQ qubit Fourier transform in the Na2_2 molecule was carried out for up to 5 qubits. The classical computation effort required to obtain the algorithm with a given fidelity is estimated to scale exponentially with the number of levels. The observed moderate scaling of the pulse intensity with the number of qubits in the transformation is rationalized.Comment: 32 pages, 6 figure

    Measurement of the quasi-elastic axial vector mass in neutrino-oxygen interactions

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    The weak nucleon axial-vector form factor for quasi-elastic interactions is determined using neutrino interaction data from the K2K Scintillating Fiber detector in the neutrino beam at KEK. More than 12,000 events are analyzed, of which half are charged-current quasi-elastic interactions nu-mu n to mu- p occurring primarily in oxygen nuclei. We use a relativistic Fermi gas model for oxygen and assume the form factor is approximately a dipole with one parameter, the axial vector mass M_A, and fit to the shape of the distribution of the square of the momentum transfer from the nucleon to the nucleus. Our best fit result for M_A = 1.20 \pm 0.12 GeV. Furthermore, this analysis includes updated vector form factors from recent electron scattering experiments and a discussion of the effects of the nucleon momentum on the shape of the fitted distributions.Comment: 14 pages, 10 figures, 6 table

    Search for the W-exchange decays B0 --> Ds(*)- Ds(*)+

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    We report a search for the decays B0DsDs+B^{0} \to D_{s}^{-} D_{s}^{+}, B0DsDs+B^{0} \to D_{s}^{*-} D_{s}^{+}, B0DsDs+B^{0} \to D_{s}^{*-} D_{s}^{*+} in a sample of 232 million Υ(4S)\Upsilon(4S) decays to \BBb ~pairs collected with the \babar detector at the PEP-II asymmetric-energy e+ee^+ e^- storage ring. We find no significant signal and set upper bounds for the branching fractions: B(B0DsDs+)<1.0×104,B(B0DsDs+)<1.3×104{\cal B}(B^{0} \to D_{s}^{-} D_{s}^{+}) < 1.0 \times 10^{-4}, {\cal B}(B^{0} \to D_{s}^{*-} D_{s}^{+}) < 1.3 \times 10^{-4} and B(B0DsDs+)<2.4×104{\cal B}(B^{0} \to D_{s}^{*-} D_{s}^{*+}) < 2.4 \times 10^{-4} at 90% confidence level.Comment: 8 pages, 2 figures, submitted to PRD-R

    Measurement of Branching Fraction and Dalitz Distribution for B0->D(*)+/- K0 pi-/+ Decays

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    We present measurements of the branching fractions for the three-body decays B0 -> D(*)-/+ K0 pi^+/-andtheirresonantsubmodes and their resonant submodes B0 -> D(*)-/+ K*+/- using a sample of approximately 88 million BBbar pairs collected by the BABAR detector at the PEP-II asymmetric energy storage ring. We measure: B(B0->D-/+ K0 pi+/-)=(4.9 +/- 0.7(stat) +/- 0.5 (syst)) 10^{-4} B(B0->D*-/+ K0 pi+/-)=(3.0 +/- 0.7(stat) +/- 0.3 (syst)) 10^{-4} B(B0->D-/+ K*+/-)=(4.6 +/- 0.6(stat) +/- 0.5 (syst)) 10^{-4} B(B0->D*-/+ K*+/-)=(3.2 +/- 0.6(stat) +/- 0.3 (syst)) 10^{-4} From these measurements we determine the fractions of resonant events to be : f(B0-> D-/+ K*+/-) = 0.63 +/- 0.08(stat) +/- 0.04(syst) f(B0-> D*-/+ K*+/-) = 0.72 +/- 0.14(stat) +/- 0.05(syst)Comment: 7 pages, 3 figures submitted to Phys. Rev. Let

    Measurement of the B+ --> p pbar K+ Branching Fraction and Study of the Decay Dynamics

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    With a sample of 232x10^6 Upsilon(4S) --> BBbar events collected with the BaBar detector, we study the decay B+ --> p pbar K+ excluding charmonium decays to ppbar. We measure a branching fraction Br(B+ --> p pbar K+)=(6.7+/-0.5+/-0.4)x10^{-6}. An enhancement at low ppbar mass is observed and the Dalitz plot asymmetry suggests dominance of the penguin amplitude in this B decay. We search for a pentaquark candidate Theta*++ decaying into pK+ in the mass range 1.43 to 2.00 GeV/c2 and set limits on Br(B+ --> Theta*++pbar)xBr(Theta*++ --> pK+) at the 10^{-7} level.Comment: 8 pages, 7 postscript figures, submitted to Phys. Rev. D (Rapid Communications

    Study of e+e- --> pi+ pi- pi0 process using initial state radiation with BABAR

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    The process e+e- --> pi+ pi- pi0 gamma has been studied at a center-of-mass energy near the Y(4S) resonance using a 89.3 fb-1 data sample collected with the BaBar detector at the PEP-II collider. From the measured 3pi mass spectrum we have obtained the products of branching fractions for the omega and phi mesons, B(omega --> e+e-)B(omega --> 3pi)=(6.70 +/- 0.06 +/- 0.27)10-5 and B(phi --> e+e-)B(phi --> 3pi)=(4.30 +/- 0.08 +/- 0.21)10-5, and evaluated the e+e- --> pi+ pi- pi0 cross section for the e+e- center-of-mass energy range 1.05 to 3.00 GeV. About 900 e+e- --> J/psi gamma --> pi+ pi- pi0 gamma events have been selected and the branching fraction B(J/psi --> pi+ pi- pi0)=(2.18 +/- 0.19)% has been measured.Comment: 21 pages, 37 postscript figues, submitted to Phys. Rev.

    Single hadron response measurement and calorimeter jet energy scale uncertainty with the ATLAS detector at the LHC

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    The uncertainty on the calorimeter energy response to jets of particles is derived for the ATLAS experiment at the Large Hadron Collider (LHC). First, the calorimeter response to single isolated charged hadrons is measured and compared to the Monte Carlo simulation using proton-proton collisions at centre-of-mass energies of sqrt(s) = 900 GeV and 7 TeV collected during 2009 and 2010. Then, using the decay of K_s and Lambda particles, the calorimeter response to specific types of particles (positively and negatively charged pions, protons, and anti-protons) is measured and compared to the Monte Carlo predictions. Finally, the jet energy scale uncertainty is determined by propagating the response uncertainty for single charged and neutral particles to jets. The response uncertainty is 2-5% for central isolated hadrons and 1-3% for the final calorimeter jet energy scale.Comment: 24 pages plus author list (36 pages total), 23 figures, 1 table, submitted to European Physical Journal

    Measurements of fiducial and differential cross sections for Higgs boson production in the diphoton decay channel at s√=8 TeV with ATLAS

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    Measurements of fiducial and differential cross sections are presented for Higgs boson production in proton-proton collisions at a centre-of-mass energy of s√=8 TeV. The analysis is performed in the H → γγ decay channel using 20.3 fb−1 of data recorded by the ATLAS experiment at the CERN Large Hadron Collider. The signal is extracted using a fit to the diphoton invariant mass spectrum assuming that the width of the resonance is much smaller than the experimental resolution. The signal yields are corrected for the effects of detector inefficiency and resolution. The pp → H → γγ fiducial cross section is measured to be 43.2 ±9.4(stat.) − 2.9 + 3.2 (syst.) ±1.2(lumi)fb for a Higgs boson of mass 125.4GeV decaying to two isolated photons that have transverse momentum greater than 35% and 25% of the diphoton invariant mass and each with absolute pseudorapidity less than 2.37. Four additional fiducial cross sections and two cross-section limits are presented in phase space regions that test the theoretical modelling of different Higgs boson production mechanisms, or are sensitive to physics beyond the Standard Model. Differential cross sections are also presented, as a function of variables related to the diphoton kinematics and the jet activity produced in the Higgs boson events. The observed spectra are statistically limited but broadly in line with the theoretical expectations

    Search for squarks and gluinos in events with isolated leptons, jets and missing transverse momentum at s√=8 TeV with the ATLAS detector

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    The results of a search for supersymmetry in final states containing at least one isolated lepton (electron or muon), jets and large missing transverse momentum with the ATLAS detector at the Large Hadron Collider are reported. The search is based on proton-proton collision data at a centre-of-mass energy s√=8 TeV collected in 2012, corresponding to an integrated luminosity of 20 fb−1. No significant excess above the Standard Model expectation is observed. Limits are set on supersymmetric particle masses for various supersymmetric models. Depending on the model, the search excludes gluino masses up to 1.32 TeV and squark masses up to 840 GeV. Limits are also set on the parameters of a minimal universal extra dimension model, excluding a compactification radius of 1/R c = 950 GeV for a cut-off scale times radius (ΛR c) of approximately 30
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