810 research outputs found

    Intracranial hypertension and cortical thickness in syndromic craniosynostosis

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    Aim: To evaluate the impact of risk factors for intracranial hypertension (ICH) on cerebral cortex thickness in syndromic craniosynostosis. Method: ICH risk factors including papilloedema, hydrocephalus, obstructive sleep apnea (OSA), cerebellar tonsillar position, occipitofrontal circumference (OFC) curve deflection, age, and sex were collected from the records of patients with syndromic craniosynostosis (Apert, Crouzon, Pfeiffer, Muenke, Saethre-Chotzen syndromes) and imaging. Magnetic resonance images were analysed and exported for statistical analysis. A linear mixed model was developed to determine correlations with cerebral cortex thickness changes. Results: In total, 171 scans from 107 patients (83 males, 88 females, mean age 8y 10mo, range 1y 1mo–34y, SD 5y 9mo) were evaluated. Mean cortical thickness in this cohort was 2.78mm (SD 0.17). Previous findings of papilloedema (p=0.036) and of hydrocephalus (p=0.007) were independently associated with cortical thinning. Cortical thickness did not vary significantly by sex (p=0.534), syndrome (p=0.896), OSA (p=0.464), OFC (p=0.375), or tonsillar position (p=0.682). Interpretation: Detection of papilloedema or hydrocephalus in syndromic craniosynostosis is associated with significant changes in cortical thickness, supporting the need for preventative rather than reactive treatment strategies

    Signatures of Classical Diffusion in Quantum Fluctuations of 2D Chaotic Systems

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    We consider a two-dimensional (2D) generalization of the standard kicked-rotor (KR) and show that it is an excellent model for the study of 2D quantum systems with underlying diffusive classical dynamics. First we analyze the distribution of wavefunction intensities and compare them with the predictions derived in the framework of diffusive {\it disordered} samples. Next, we turn the closed system into an open one by constructing a scattering matrix. The distribution of the resonance widths P(Γ){\cal P}(\Gamma) and Wigner delay times P(τW){\cal P}(\tau_W) are investigated. The forms of these distributions are obtained for different symmetry classes and the traces of classical diffusive dynamics are identified. Our theoretical arguments are supported by extensive numerical calculations.Comment: 20 pages; 12 figure

    Culture and Personal Epistemology: U.S. and Middle Eastern Students’ beliefs about Scientific Knowledge and Knowing

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    Middle Eastern (Omani) and Western (U.S.) students’ beliefs about knowledge and knowing in the sciences were compared on four dimensions of personal epistemology proposed by Hofer and Pintrich ( Review of Educational Research (1997), 67 , 88–140). As predicted, given their experiences with comparatively traditional political and religious institutions, Omani more so than U.S. college students were more likely to accept scientific authorities as the basis of scientific truth. Furthermore, Omani men were more accepting of authorities than were Omani women, but there was no gender difference among U.S. students. Omani more than U.S. students also believed that knowledge in the sciences was simpler and more certain, which is consistent with comparisons between U.S. and Asian students (e.g., Qian & Pan, 2002, A comparision of epistemological beliefs and learning from science text between American and Chinese high school students. In B. K. Hofer & P. R. Pintrich (Eds.), Personal epistomology: The psychology of beliefs about knowledge and knowing (pp. 365–385), Mahwah, NJ: Erlbaum). Students in the two countries did not differ, however, in whether their beliefs were based on personal opinions versus systematic evidence. Suggestions for further research included directly assessing experiences with, and attitudes toward, authorities in academic and other areas of students’ lives.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43812/1/11218_2005_Article_1826.pd

    Observation of the Ξc+\Xi_c^+ Charmed Baryon Decays to Σ+Kπ+\Sigma^+ K^-\pi^+, Σ+Kˉ0\Sigma^+ \bar{K}^{*0}, and ΛKπ+π+\Lambda K^-\pi^+\pi^+

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    We have observed two new decay modes of the charmed baryon Ξc+\Xi_c^+ into Σ+Kπ+\Sigma^+ K^-\pi^+ and Σ+Kˉ0\Sigma^+ \bar{K}^{*0} using data collected with the CLEO II detector. We also present the first measurement of the branching fraction for the previously observed decay mode Ξc+ΛKπ+π+\Xi_c^+\to\Lambda K^-\pi^+\pi^+. The branching fractions for these three modes relative to Ξc+Ξπ+π+\Xi_c^+\to\Xi^-\pi^+\pi^+ are measured to be 1.18±0.26±0.171.18 \pm 0.26 \pm 0.17, 0.92±0.27±0.140.92 \pm 0.27 \pm 0.14, and 0.58±0.16±0.070.58 \pm 0.16 \pm 0.07, respectively.Comment: 12 page uuencoded postscript file, postscript file also available through http://w4.lns.cornell.edu/public/CLN

    Production and Decay of D_1(2420)^0 and D_2^*(2460)^0

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    We have investigated D+πD^{+}\pi^{-} and D+πD^{*+}\pi^{-} final states and observed the two established L=1L=1 charmed mesons, the D1(2420)0D_1(2420)^0 with mass 242122+1+22421^{+1+2}_{-2-2} MeV/c2^{2} and width 2053+6+320^{+6+3}_{-5-3} MeV/c2^{2} and the D2(2460)0D_2^*(2460)^0 with mass 2465±3±32465 \pm 3 \pm 3 MeV/c2^{2} and width 2876+8+628^{+8+6}_{-7-6} MeV/c2^{2}. Properties of these final states, including their decay angular distributions and spin-parity assignments, have been studied. We identify these two mesons as the jlight=3/2j_{light}=3/2 doublet predicted by HQET. We also obtain constraints on {\footnotesize ΓS/(ΓS+ΓD)\Gamma_S/(\Gamma_S + \Gamma_D)} as a function of the cosine of the relative phase of the two amplitudes in the D1(2420)0D_1(2420)^0 decay.Comment: 15 pages in REVTEX format. hardcopies with figures can be obtained by sending mail to: [email protected]

    Measurement of the branching fraction for Υ(1S)τ+τ\Upsilon (1S) \to \tau^+ \tau^-

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    We have studied the leptonic decay of the Υ(1S)\Upsilon (1S) resonance into tau pairs using the CLEO II detector. A clean sample of tau pair events is identified via events containing two charged particles where exactly one of the particles is an identified electron. We find B(Υ(1S)τ+τ)=(2.61 ± 0.12 +0.090.13)B(\Upsilon(1S) \to \tau^+ \tau^-) = (2.61~\pm~0.12~{+0.09\atop{-0.13}})%. The result is consistent with expectations from lepton universality.Comment: 9 pages, RevTeX, two Postscript figures available upon request, CLNS 94/1297, CLEO 94-20 (submitted to Physics Letters B

    Observation of a Narrow Resonance of Mass 2.46 GeV/c^2 Decaying to D_s^*+ pi^0 and Confirmation of the D_sJ^* (2317) State

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    Using 13.5 inverse fb of e+e- annihilation data collected with the CLEO II detector we have observed a narrow resonance in the Ds*+pi0 final state, with a mass near 2.46 GeV. The search for such a state was motivated by the recent discovery by the BaBar Collaboration of a narrow state at 2.32 GeV, the DsJ*(2317)+ that decays to Ds+pi0. Reconstructing the Ds+pi0 and Ds*+pi0 final states in CLEO data, we observe peaks in both of the corresponding reconstructed mass difference distributions, dM(Dspi0)=M(Dspi0)-M(Ds) and dM(Ds*pi0)=M(Ds*pi0)-M(Ds*), both of them at values near 350 MeV. We interpret these peaks as signatures of two distinct states, the DsJ*(2317)+ plus a new state, designated as the DsJ(2463)+. Because of the similar dM values, each of these states represents a source of background for the other if photons are lost, ignored or added. A quantitative accounting of these reflections confirms that both states exist. We have measured the mean mass differences = 350.0 +/- 1.2 [stat] +/- 1.0 [syst] MeV for the DsJ*(2317) state, and = 351.2 +/- 1.7 [stat] +/- 1.0 [syst] MeV for the new DsJ(2463)+ state. We have also searched, but find no evidence, for decays of the two states via the channels Ds*+gamma, Ds+gamma, and Ds+pi+pi-. The observations of the two states at 2.32 and 2.46 GeV, in the Ds+pi0 and Ds*+pi0 decay channels respectively, are consistent with their interpretations as (c anti-strange) mesons with orbital angular momentum L=1, and spin-parities of 0+ and 1+.Comment: 16 pages postscript, also available through http://w4.lns.cornell.edu/public/CLNS, version to be published in Physical Review D; minor modifications and fixes to typographical errors, plus an added section on production properties. The main results are unchanged; they supersede those reported in hep-ex/030501

    Measurement of the Charge Asymmetry in BK(892)±πB\to K^* (892)^{\pm}\pi^{\mp}

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    We report on a search for a CP-violating asymmetry in the charmless hadronic decay B -> K*(892)+- pi-+, using 9.12 fb^-1 of integrated luminosity produced at \sqrt{s}=10.58 GeV and collected with the CLEO detector. We find A_{CP}(B -> K*(892)+- pi-+) = 0.26+0.33-0.34(stat.)+0.10-0.08(syst.), giving an allowed interval of [-0.31,0.78] at the 90% confidence level.Comment: 7 pages postscript, also available through http://w4.lns.cornell.edu/public/CLNS, submitted to PR

    Study of the q^2-Dependence of B --> pi ell nu and B --> rho(omega)ell nu Decay and Extraction of |V_ub|

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    We report on determinations of |Vub| resulting from studies of the branching fraction and q^2 distributions in exclusive semileptonic B decays that proceed via the b->u transition. Our data set consists of the 9.7x10^6 BBbar meson pairs collected at the Y(4S) resonance with the CLEO II detector. We measure B(B0 -> pi- l+ nu) = (1.33 +- 0.18 +- 0.11 +- 0.01 +- 0.07)x10^{-4} and B(B0 -> rho- l+ nu) = (2.17 +- 0.34 +0.47/-0.54 +- 0.41 +- 0.01)x10^{-4}, where the errors are statistical, experimental systematic, systematic due to residual form-factor uncertainties in the signal, and systematic due to residual form-factor uncertainties in the cross-feed modes, respectively. We also find B(B+ -> eta l+ nu) = (0.84 +- 0.31 +- 0.16 +- 0.09)x10^{-4}, consistent with what is expected from the B -> pi l nu mode and quark model symmetries. We extract |Vub| using Light-Cone Sum Rules (LCSR) for 0<= q^2<16 GeV^2 and Lattice QCD (LQCD) for 16 GeV^2 <= q^2 < q^2_max. Combining both intervals yields |Vub| = (3.24 +- 0.22 +- 0.13 +0.55/-0.39 +- 0.09)x10^{-3}$ for pi l nu, and |Vub| = (3.00 +- 0.21 +0.29/-0.35 +0.49/-0.38 +-0.28)x10^{-3} for rho l nu, where the errors are statistical, experimental systematic, theoretical, and signal form-factor shape, respectively. Our combined value from both decay modes is |Vub| = (3.17 +- 0.17 +0.16/-0.17 +0.53/-0.39 +-0.03)x10^{-3}.Comment: 45 pages postscript, also available through http://w4.lns.cornell.edu/public/CLNS, submitted to PR
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