290 research outputs found

    ππ\pi\pi Scattering in Three Flavour ChPT

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    We present the scattering lengths for the ππ\pi\pi processes in the three flavour Chiral Perturbation Theory (ChPT) framework at next-to-next-to-leading order. We then combine this calculation with the determination of the parameters from Ke4K_{e4} and the masses and decay constants and compare with the results of a dispersive analysis of ππ\pi\pi scattering. The comparison indicates a small but nonzero value for the 1/Nc1/N_c suppressed NLO low energy constants L4rL_4^r and L6rL_6^r.Comment: 30 page

    Non-Equilibrium Quasiclassical Theory for Josephson Structures

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    We present a non-equilibrium quasiclassical formalism suitable for studying linear response ac properties of Josephson junctions. The non-equilibrium self-consistency equations are satisfied, to very good accuracy, already in zeroth iteration. We use the formalism to study ac Josephson effect in a ballistic superconducting point contact. The real and imaginary parts of the ac linear conductance are calculated both analytically (at low frequencies) and numerically (at arbitrary frequency). They show strong temperature, frequency, and phase dependence. Many anomalous properties appear near phi = pi. We ascribe them to the presence of zero energy bound states.Comment: 11 pages, 9 figures, Final version to appear in PR

    Relations at Order p6p^6 in Chiral Perturbation Theory

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    We report on a search of relations valid at order p6p^6 in Chiral Perturbation Theory. We have found relations between ππ\pi\pi, πK\pi K scattering, Kℓ4K_{\ell4} decays, masses and decay constants and scalar and vector form factors. In this paper we give the relations and a first numerical check of them.Comment: 18 pages, numerical discussion extended including a new figur

    First narrow-band search for continuous gravitational waves from known pulsars in advanced detector data

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    Spinning neutron stars asymmetric with respect to their rotation axis are potential sources of continuous gravitational waves for ground-based interferometric detectors. In the case of known pulsars a fully coherent search, based on matched filtering, which uses the position and rotational parameters obtained from electromagnetic observations, can be carried out. Matched filtering maximizes the signalto- noise (SNR) ratio, but a large sensitivity loss is expected in case of even a very small mismatch between the assumed and the true signal parameters. For this reason, narrow-band analysis methods have been developed, allowing a fully coherent search for gravitational waves from known pulsars over a fraction of a hertz and several spin-down values. In this paper we describe a narrow-band search of 11 pulsars using data from Advanced LIGO’s first observing run. Although we have found several initial outliers, further studies show no significant evidence for the presence of a gravitational wave signal. Finally, we have placed upper limits on the signal strain amplitude lower than the spin-down limit for 5 of the 11 targets over the bands searched; in the case of J1813-1749 the spin-down limit has been beaten for the first time. For an additional 3 targets, the median upper limit across the search bands is below the spin-down limit. This is the most sensitive narrow-band search for continuous gravitational waves carried out so far

    Development and reliability of the AOSpine CROST (Clinician Reported Outcome Spine Trauma): a tool to evaluate and predict outcomes from clinician’s perspective

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    Purpose: To report on the development of AOSpine CROST (Clinician Reported Outcome Spine Trauma) and results of an initial reliability study. Methods: The AOSpine CROST was developed using an iterative approach of multiple cycles of development, review, and revision including an expert clinician panel. Subsequently, a reliability study was performed among an expert panel who were provided with 20 spine trauma cases, administered twice with 4-week interval. The results of the developmental process were analyzed using descriptive statistics, the reliability per parameter using Kappa statistics, inter-rater rater agreement using intraclass correlation coefficient (ICC), and internal consistency using Cronbach’s α. Results: The AOSpine CROST was developed and consisted of 10 parameters, 2 of which are only applicable for surgically treated patents (‘Wound healing’ and ‘Implants’). A dichotomous scoring system (‘yes’ or ‘no’ response) was incorporated to express expected problems for the short term and long term. In the reliability study, 16 (84.2%) participated in the first round and 14 (73.7%) in the second. Intra-rater reliability was fair to good for both time points (Îș = 0.40–0.80 and Îș = 0.31–0.67). Results of inter-rater reliability were lower (Îș = 0.18–0.60 and Îș = 0.16–0.46). Inter-rater agreement for total scores showed moderate results (ICC = 0.52–0.60), and the internal consistency was acceptable (α = 0.76–0.82). Conclusions: The AOSpine CROST, an outcome tool for the surgeons, was developed using an iterative process. An initial reliability analysis showed fair to moderate results and acceptable internal consistency. Further clinical validation studies will be performed to further validate the tool

    Unraveling genetic predisposition to familial or early onset gastric cancer using germline whole-exome sequencing

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    Recognition of individuals with a genetic predisposition to gastric cancer (GC) enables preventive measures. However, the underlying cause of genetic susceptibility to gastric cancer remains largely unexplained. We performed germline whole-exome sequencing on leukocyte DNA of 54 patients from 53 families with genetically unexplained diffuse-type and intestinal-type GC to identify novel GC-predisposing candidate genes. As young age at diagnosis and familial clustering are hallmarks of genetic tumor susceptibility, we selected patients that were diagnosed below the age of 35, patients from families with two cases of GC at or below age 60 and patients from families with three GC cases at or below age 70. All included individuals were tested negative for germline CDH1 mutations before or during the study. Variants that were possibly deleterious according to in silico predictions were filtered using several independent approaches that were based on gene function and gene mutation burden in controls. Despite a rigorous search, no obvious candidate GC predisposition genes were identified. This negative result stresses the importance of future research studies in large, homogeneous cohorts
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