5,800 research outputs found

    Unbounded-error One-way Classical and Quantum Communication Complexity

    Full text link
    This paper studies the gap between quantum one-way communication complexity Q(f)Q(f) and its classical counterpart C(f)C(f), under the {\em unbounded-error} setting, i.e., it is enough that the success probability is strictly greater than 1/2. It is proved that for {\em any} (total or partial) Boolean function ff, Q(f)=C(f)/2Q(f)=\lceil C(f)/2 \rceil, i.e., the former is always exactly one half as large as the latter. The result has an application to obtaining (again an exact) bound for the existence of (m,n,p)(m,n,p)-QRAC which is the nn-qubit random access coding that can recover any one of mm original bits with success probability p\geq p. We can prove that (m,n,>1/2)(m,n,>1/2)-QRAC exists if and only if m22n1m\leq 2^{2n}-1. Previously, only the construction of QRAC using one qubit, the existence of (O(n),n,>1/2)(O(n),n,>1/2)-RAC, and the non-existence of (22n,n,>1/2)(2^{2n},n,>1/2)-QRAC were known.Comment: 9 pages. To appear in Proc. ICALP 200

    Paramagnonlike excitations and spin diffusion in magnetic resonance studies of copper oxide superconductors

    Get PDF
    The relaxation function theory for a doped two-dimensional Heisenberg antiferromagnetic system in the paramagnetic state for all wave vectors through the Brillouin zone is presented in view of low frequency response of high-TcT_c copper oxide superconductors. We deduced the regions of long lifetime [T400(14x)T \lesssim 400(1-4x) K] and "overdamped" [T700(14x)T \gtrsim 700(1-4x) K] paramagnonlike excitations in the temperature (TT)-doping index (xx) phase diagram from plane oxygen nuclear spin-lattice relaxation rate 17(1/T1)^{17}(1/T_1) data in up to optimally doped La2x_{2-x}Srx_{x}CuO4_{4} thus providing the regimes for the spin wave concept and the ''overdamped'' mode.Comment: Physical Review B, accepted, in pres

    Conserved Density Fluctuation and Temporal Correlation Function in HTL Perturbation Theory

    Full text link
    Considering recently developed Hard Thermal Loop perturbation theory that takes into account the effect of the variation of the external field through the fluctuations of a conserved quantity we calculate the temporal component of the Euclidian correlation function in the vector channel. The results are found to be in good agreement with the very recent results obtained within the quenched approximation of QCD and small values of the quark mass (0.1T\sim 0.1T) on improved lattices of size 1283×Nτ128^3\times N_\tau at (Nτ=40, T=1.2TCN_\tau=40, \ T=1.2T_C), (Nτ=48, T=1.45TCN_\tau=48, \ T=1.45T_C), and (Nτ=16, T=2.98TCN_\tau=16, \ T=2.98T_C), where NτN_\tau is the temporal extent of the lattice. This suggests that the results from lattice QCD and Hard Thermal Loop perturbation theory are in close proximity for a quantity associated with the conserved density fluctuation.Comment: 16 pages, 4 figures; One para added in introduction, Fig 1 modified; Accepted in Phys. Rev.

    Regulation of phosphate transport in proximal tubules

    Get PDF
    Homeostasis of inorganic phosphate (Pi) is primarily an affair of the kidneys. Reabsorption of the bulk of filtered Pi occurs along the renal proximal tubule and is initiated by apically localized Na+-dependent Pi cotransporters. Tubular Pi reabsorption and therefore renal excretion of Pi is controlled by a number of hormones, including phosphatonins, and metabolic factors. In most cases, regulation of Pi reabsorption is achieved by changing the apical abundance of Na+/Pi cotransporters. The regulatory mechanisms involve various signaling pathways and a number of proteins that interact with Na+/Pi cotransporter

    A Search for H2CO 6cm Emission toward Young Stellar Objects III: VLA Observations

    Full text link
    We report the results of our third survey for formaldehyde (H2CO) 6cm maser emission in the Galaxy. Using the Very Large Array, we detected two new H2CO maser sources (G23.01-0.41 and G25.83-0.18), thus increasing the sample of known H2CO maser regions in the Galaxy to seven. We review the characteristics of the G23.01-0.41 and G25.83-0.18 star forming regions. The H2CO masers in G23.01-0.41 and G25.83-0.18 share several properties with the other known H2CO masers, in particular, emission from rich maser environments and close proximity to very young massive stellar objects.Comment: Accepted for publication in the Astrophysical Journal Supplement Serie

    Laminin and fibronectin in rectal adenocarcinoma: relationship to tumour grade, stage and metastasis.

    Get PDF
    Using an immunoperoxidase procedure, we have examined the distribution of laminin and fibronectin in normal human large intestinal mucosa and in 50 cases of rectal adenocarcinoma for which extensive clinical follow up was available. In normal tissue, laminin staining was largely restricted to basement membranes, including that underlying the epithelial cells, whereas fibronectin was found in both basement membranes and surrounding connective tissue. In rectal carcinomas, basement membrane-like staining for laminin associated with tumour cells was found in only 27 out of the 50 cases studied. Statistical analysis showed that the presence of laminin-containing basement membranes was correlated with low histological grade (well-differentiated tumours), but not with stage (progression through the bowel wall and the development of lymph node metastases) and, in a highly significant way, with a reduced incidence of distant metastases and increased patient survival. Although fibronectin was found in tumour cell basement membranes where these were present, it was also found in the stroma of all 50 tumours. There was no apparent correlation between the presence of stromal fibronectin and grade, stage or development of metastases. Finally, attention is drawn to some of the technical difficulties in detecting basement membrane antigens in formalin-fixed tissue, the material most frequently available for retrospective study

    Evidence of momentum dependent hybridization in Ce2Co0.8Si3.2

    Full text link
    We studied the electronic structure of the Kondo lattice system Ce2Co0.8Si3.2 by angle-resolved photoemission spectroscopy (ARPES). The spectra obtained below the coherence temperature consist of a Kondo resonance, its spin-orbit partner and a number of dispersing bands. The quasiparticle weight related to the Kondo peak depends strongly on Fermi vectors associated with bulk bands. This indicates a highly anisotropic hybridization between conduction band and 4f electrons - V_{cf} in Ce2Co0.8Si3.2.Comment: 6 page

    Superficial siderosis: a potential diagnostic marker of cerebral amyloid angiopathy in Alzheimer disease

    Get PDF
    Abstract BACKGROUND AND PURPOSE: Superficial siderosis of the central nervous system results from chronic bleeding in the superficial layers of the cortex and spinal cord. In cerebral amyloid angiopathy (CAA), there is amyloid deposition in meningeal and meningo-cortical arteries and capillaries, predisposing them to rupture. CAA is frequently associated with Alzheimer disease (AD). METHODS: We report a series of 3 AD patients with MRI evidence of superficial siderosis. Two had neuropathological examination confirming superficial siderosis, AD, and CAA. CONCLUSIONS: Superficial siderosis should be recognized within the spectrum of AD with CAA and considered as a possible antemortem diagnostic feature

    Vortex pairing in two-dimensional Bose gases

    Get PDF
    Recent experiments on ultracold Bose gases in two dimensions have provided evidence for the existence of the Berezinskii-Kosterlitz-Thouless (BKT) phase via analysis of the interference between two independent systems. In this work we study the two-dimensional quantum degenerate Bose gas at finite temperature using the projected Gross-Pitaevskii equation classical field method. While this describes the highly occupied modes of the gas below a momentum cutoff, we have developed a method to incorporate the higher momentum states in our model. We concentrate on finite-sized homogeneous systems in order to simplify the analysis of the vortex pairing. We determine the dependence of the condensate fraction on temperature and compare this to the calculated superfluid fraction. By measuring the first order correlation function we determine the boundary of the Bose-Einstein condensate and BKT phases, and find it is consistent with the superfluid fraction decreasing to zero. We reveal the characteristic unbinding of vortex pairs above the BKT transition via a coarse-graining procedure. Finally, we model the procedure used in experiments to infer system correlations [Hadzibabic et al., Nature 441, 1118 (2006)], and quantify its level of agreement with directly calculated in situ correlation functions.Comment: published versio

    Probing ultracold Fermi gases with light-induced gauge potentials

    Get PDF
    We theoretically investigate the response of a two component Fermi gas to vector potentials which couple separately to the two spin components. Such vector potentials may be implemented in ultracold atomic gases using optically dressed states. Our study indicates that light-induced gauge potentials may be used to probe the properies of the interacting ultracold Fermi gas, providing. amongst other things, ways to measure the superfluid density and the strength of pairing.Comment: 8 pages, 3 figure
    corecore