8,228 research outputs found

    Production at High pTp_T in Central Au+Au and p+pp+p collisions at sNN=200\sqrt{s_{_{NN}}} = 200 GeV in STAR

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    he ρ0\rho^0 production at high-pTp_T (5.0 pT\leq p_T \leq 10.0 GeV/cc) measured in minimum bias p+pp+p, Au+Au and central Au+Au collisions in the STAR detector are presented. The ρ0/π\rho^0/\pi ratio measured in p+pp+p is compared to PYTHIA calculations as a test of perturbative quantum chromodynamics (pQCD) that describes reasonably well particle production from hard processes. The ρ0\rho^0 nuclear modification factor are also presented. In p+pp+p collisions, charged pions and (anti-)protons are measured in the range 5.0 pT\leq p_T \leq 15.0 GeV/cc and the anti-particle to particle ratio and the baryon to meson ratios of these hadrons are discussed.Comment: 4 pages, 8 figures, proccedings for QM200

    The impact of epilepsy surgery on sex hormones and the menstrual cycle in female patients

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    AbstractWe investigated the impact of temporal lobe epilepsy surgery on sex hormones and menstrual cycles. Sixteen female patients with temporal lobe epilepsy were investigated prior to surgery and 3, 6, and 12 months after surgery. The patients received carbamazepine (CBZ) as monotherapy (10 patients ) or in combination with other antiepileptic drugs (six patients ). Antiepileptic drugs were maintained after surgery. During the 1-year follow-up after surgery eight patients (50%) remained completely free of seizures. In another four patients (25%) only rare disabling seizures occurred. There were no significant differences between pre-surgical and post-surgical serum concentrations of testosterone, free testosterone, prolactin, dehydroepiandrosterone sulfate, growth hormone, cortisol and sex hormone binding globulin. There was, however, a significant increase in serum androstenedione concentration 6 months post-surgically (P< 0.02). Documentation of menstrual cycles in addition to laboratory parameters revealed individual post-surgical changes of the menstrual cycle in eight patients . Four patients had a change in menstrual periodicity: two patients with complete seizure control had regular cycles instead of oligomenorrhoea and two patients with incomplete seizure control had oligomenorrhoea instead of regular cycles. These data indicate that at least in some patients with temporal lobe epilepsy surgical treatment influences menstrual periodicity

    Monitoring accretion rate variability in the Orion Nebula Cluster with the Wendelstein Wide Field Imager

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    The understanding of the accretion process has a central role in the understanding of star and planet formation. We aim to test how accretion variability influences previous correlation analyses of the relation between X-ray activity and accretion rates, which is important for understanding the evolution of circumstellar disks and disk photoevaporation. We monitored accreting stars in the Orion Nebula Cluster from November 24, 2014, until February 17, 2019, for 42 epochs with the Wendelstein Wide Field Imager in the Sloan Digital Sky Survey u'g'r' filters on the 2 m Fraunhofer Telescope on Mount Wendelstein. Mass accretion rates were determined from the measured ultraviolet excess. The influence of the mass accretion rate variability on the relation between X-ray luminosities and mass accretion rates was analyzed statistically. We find a typical interquartile range of ~ 0.3 dex for the mass accretion rate variability on timescales from weeks to ~ 2 years. The variability has likely no significant influence on a correlation analysis of the X-ray luminosity and the mass accretion rate observed at different times when the sample size is large enough. The observed anticorrelation between the X-ray luminosity and the mass accretion rate predicted by models of photoevaporation-starved accretion is likely not due to a bias introduced by different observing times

    Ionization energy of Li 6,7 determined by triple-resonance laser spectroscopy

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    Rydberg level energies for Li7 were measured using triple-resonance laser excitation, followed by drifted field ionization. In addition to the principal n P2 series, weak Stark mixing from residual electric fields allowed observation of n S2 and hydrogenic Stark manifold series at higher n. Limit analyses for the series yield the spectroscopic ionization energy EI (Li7) =43 487.159 40 (18) cm-1. The Li 6,7 isotope shift (IS) was measured in selected n P2 Rydberg levels and extrapolation to the series limit yields IS (EI) 7,6 =18 067.54 (21) MHz. Results are compared with recent theoretical calculations: EI values from experiment and theory agree to within 0.0011 cm-1, with the remaining discrepancy comparable to uncertainty in QED corrections of order α4 Ry. The difference between experiment and calculated mass-based IS (EI) yields a change in nuclear charge radii between the two isotopes δ r2 7,6 =-0.60 (10) fm2. © 2007 The American Physical Society

    Diffusion and jump-length distribution in liquid and amorphous Cu33_{33}Zr67_{67}

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    Using molecular dynamics simulation, we calculate the distribution of atomic jum ps in Cu33_{33}Zr67_{67} in the liquid and glassy states. In both states the distribution of jump lengths can be described by a temperature independent exponential of the length and an effective activation energy plus a contribution of elastic displacements at short distances. Upon cooling the contribution of shorter jumps dominates. No indication of an enhanced probability to jump over a nearest neighbor distance was found. We find a smooth transition from flow in the liquid to jumps in the g lass. The correlation factor of the diffusion constant decreases with decreasing temperature, causing a drop of diffusion below the Arrhenius value, despite an apparent Arrhenius law for the jump probability

    Separated Oscillatory Fields for High-Precision Penning Trap Mass Spectrometry

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    Ramsey's method of separated oscillatory fields is applied to the excitation of the cyclotron motion of short-lived ions in a Penning trap to improve the precision of their measured mass. The theoretical description of the extracted ion-cyclotron-resonance line shape is derived out and its correctness demonstrated experimentally by measuring the mass of the short-lived 38^{38}Ca nuclide with an uncertainty of 1.61081.6\cdot 10^{-8} using the ISOLTRAP Penning trap mass spectrometer at CERN. The mass value of the superallowed beta-emitter 38^{38}Ca is an important contribution for testing the conserved-vector-current hypothesis of the electroweak interaction. It is shown that the Ramsey method applied to mass measurements yields a statistical uncertainty similar to that obtained by the conventional technique ten times faster.Comment: 5 pages, 4 figures, 0 table

    Search for the Hypothetical pi -> mu x Decay

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    The KARMEN collaboration has reported the possible observation of a hitherto unknown neutral and weakly interacting particle x, which is produced in the decay pi -> mu + x with a mass m(x) = 33.9 MeV. We have searched for this hypothetical decay branch by studying muons from pion decay in flight with the LEPS spectrometer at the piE3 channel at PSI and find branching ratios BR(pi- to mu- anti-x) < 4e-7 and BR(pi+ to mu+ x) < 7e-8 (95\% C.L.). Together with the limit BR > 2e-8 derived in a recent theoretical paper our result would leave only a narrow region for the existence of x if it is a heavy neutrino.Comment: 10 pages, TeX (uses epsf), 3 Postscript figures uu-encode

    Effect of anisotropic impurity scattering in superconductors

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    We discuss the weak-coupling BCS theory of a superconductor with the impurities, accounting for their anisotropic momentum-dependent potential. The impurity scattering process is considered in the t-matrix approximation and its influence on the superconducting critical temperature is studied in the Born and unitary limit for a d- and (d+s)-wave superconductors. We observe a significant dependence of the pair-breaking strength on the symmetry of the scattering potential and classify the impurity potentials according to their ability to alter T_c. A good agreement with the experimental data for Zn doping and oxygen irradiation in the overdoped cuprates is found.Comment: 31 pages, RevTex, 15 PostScript figure

    Reduction of Tc due to Impurities in Cuprate Superconductors

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    In order to explain how impurities affect the unconventional superconductivity, we study non-magnetic impurity effect on the transition temperature using on-site U Hubbard model within a fluctuation exchange (FLEX) approximation. We find that in appearance, the reduction of Tc roughly coincides with the well-known Abrikosov-Gor'kov formula. This coincidence results from the cancellation between two effects; one is the reduction of attractive force due to randomness, and another is the reduction of the damping rate of quasi-particle arising from electron interaction. As another problem, we also study impurity effect on underdoped cuprate as the system showing pseudogap phenomena. To the aim, we adopt the pairing scenario for the pseudogap and discuss how pseudogap phenomena affect the reduction of Tc by impurities. We find that 'pseudogap breaking' by impurities plays the essential role in underdoped cuprate and suppresses the Tc reduction due to the superconducting (SC) fluctuation.Comment: 14 pages, 28 figures To be published in JPS
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