742 research outputs found

    Indirect search for supersymmetry in rare B decays

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    QCD corrections to the gluino induced contribution to b --> s gamma are shown to be important in order to extract reliable bounds on the off-diagonal elements of the squark mass matrices.Comment: 4 pages including 2 postscript figure

    Final State Interactions and Khuri-Treiman Equations in η → 3π decays

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    Using extended Khuri-Treiman equations, we evaluate the final state interactions due to two-pion rescatterings to the decays η → (π^0)(π^+)(π^-) and η → (π^0)(π^0)(π^0). As subtraction to the dispersion relation we take the one-loop chiral perturbation theory result of Gasser and Leutwyler. The calculated corrections are moderate and amount to about 14% in the amplitude at the center of the decay region. A careful analysis of the errors inherent to our approach is given. As a consequence, the experimental rate of the decay can only be reproduced if the double quark mass ratio Q^(-2) ≡ (m_d - m_u)/(m_s - m̂) * (m_d + m_u)/(m_s + m̂) is increased from the usual value of 1/(24.1)^2 to 1/(22.4 ± 0.9)^2. We have also calculated the ratio of the rates of the two decays and various Dalitz Plot parameters. In particular, the linear slope a in the charged decay is different from the one-loop value and agrees better with experiment

    Critical Points and Traveling Wave in Locomotion: Experimental Evidence and Some Theoretical Considerations

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    The central pattern generator (CPG) architecture for rhythm generation remains partly elusive. We compare cat and frog locomotion results, where the component unrelated to pattern formation appears as a temporal grid, and traveling wave respectively. Frog spinal cord microstimulation with N-methyl-D-Aspartate (NMDA), a CPG activator, produced a limited set of force directions, sometimes tonic, but more often alternating between directions similar to the tonic forces. The tonic forces were topographically organized, and sites evoking rhythms with different force subsets were located close to the constituent tonic force regions. Thus CPGs consist of topographically organized modules. Modularity was also identified as a limited set of muscle synergies whose combinations reconstructed the EMGs. The cat CPG was investigated using proprioceptive inputs during fictive locomotion. Critical points identified both as abrupt transitions in the effect of phasic perturbations, and burst shape transitions, had biomechanical correlates in intact locomotion. During tonic proprioceptive perturbations, discrete shifts between these critical points explained the burst durations changes, and amplitude changes occurred at one of these points. Besides confirming CPG modularity, these results suggest a fixed temporal grid of anchoring points, to shift modules onsets and offsets. Frog locomotion, reconstructed with the NMDA synergies, showed a partially overlapping synergy activation sequence. Using the early synergy output evoked by NMDA at different spinal sites, revealed a rostrocaudal topographic organization, where each synergy is preferentially evoked from a few, albeit overlapping, cord regions. Comparing the locomotor synergy sequence with this topography suggests that a rostrocaudal traveling wave would activate the synergies in the proper sequence for locomotion. This output was reproduced in a two-layer model using this topography and a traveling wave. Together our results suggest two CPG components: modules, i.e., synergies; and temporal patterning, seen as a temporal grid in the cat, and a traveling wave in the frog. Animal and limb navigation have similarities. Research relating grid cells to the theta rhythm and on segmentation during navigation may relate to our temporal grid and traveling wave results. Winfree’s mathematical work, combining critical phases and a traveling wave, also appears important. We conclude suggesting tracing, and imaging experiments to investigate our CPG model

    Efficiency of spinal anesthesia versus general anesthesia for lumbar spinal surgery: a retrospective analysis of 544 patients.

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    BACKGROUND: Previous studies have shown varying results in selected outcomes when directly comparing spinal anesthesia to general in lumbar surgery. Some studies have shown reduced surgical time, postoperative pain, time in the postanesthesia care unit (PACU), incidence of urinary retention, postoperative nausea, and more favorable cost-effectiveness with spinal anesthesia. Despite these results, the current literature has also shown contradictory results in between-group comparisons. MATERIALS AND METHODS: A retrospective analysis was performed by querying the electronic medical record database for surgeries performed by a single surgeon between 2007 and 2011 using procedural codes 63030 for diskectomy and 63047 for laminectomy: 544 lumbar laminectomy and diskectomy surgeries were identified, with 183 undergoing general anesthesia and 361 undergoing spinal anesthesia (SA). Linear and multivariate regression analyses were performed to identify differences in blood loss, operative time, time from entering the operating room (OR) until incision, time from bandage placement to exiting the OR, total anesthesia time, PACU time, and total hospital stay. Secondary outcomes of interest included incidence of postoperative spinal hematoma and death, incidence of paraparesis, plegia, post-dural puncture headache, and paresthesia, among the SA patients. RESULTS: SA was associated with significantly lower operative time, blood loss, total anesthesia time, time from entering the OR until incision, time from bandage placement until exiting the OR, and total duration of hospital stay, but a longer stay in the PACU. The SA group experienced one spinal hematoma, which was evacuated without any long-term neurological deficits, and neither group experienced a death. The SA group had no episodes of paraparesis or plegia, post-dural puncture headaches, or episodes of persistent postoperative paresthesia or weakness. CONCLUSION: SA is effective for use in patients undergoing elective lumbar laminectomy and/or diskectomy spinal surgery, and was shown to be the more expedient anesthetic choice in the perioperative setting

    Diagnostik und Therapie der Harnleitersteinkolik

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    Summary: Acute ureteral colic presents with a complex of acute and characteristic flank pain that usually indicates the presence of a stone in the urinary tract. Diagnosis and management of renal colic have undergone considerable evolution and advancement in recent years. The application of noncontrast helical computed tomography (CT) in patients with suspected ureteral colic is one major advance in the primary diagnostic process. The superior sensitivity and specificity of helical CT allow ureterolithiasis to be diagnosed without the potential side effects of contrast media. Initial management is based on three key concepts: (A) rational and fast diagnostic process (B) effective pain control (C) and understanding of the impact of stone location and size on the natural course of the disease and definitive urologic management. These concepts are discussed in this review with reference to contemporary literatur

    Phenomenology of Mirror Fermions in the Littlest Higgs Model with T-Parity

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    Little Higgs models are an interesting alternative to explain electroweak symmetry breaking without fine-tuning. Supplemented with a discrete symmetry (T-parity) constraints from electroweak precision data are naturally evaded and also a viable dark matter candidate is obtained. T-parity implies the existence of new (mirror) fermions in addition to the heavy gauge bosons of the little Higgs models. In this paper we consider the effects of the mirror fermions on the phenomenology of the littlest Higgs model with T-parity at the LHC. We study the most promising production channels and decay chains for the new particles. We find that the mirror fermions have a large impact on the magnitude of signal rates and on the new physics signatures. Realistic background estimates are given.Comment: 13 p

    Photoselektive Vaporisation der Prostata: Erfahrungen mit Prostataadenomen >80cm3

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    Zusammenfassung: Hintergrund: Wir berichten ĂŒber unsere Erfahrungen mit der photoselektiven Vaporisation der Prostata (PVP) bei Patienten mit symptomatischer benigner Prostatahyperplasie (BPH) und Prostataadenomen >80cm3. Patienten und Methode: 201Patienten mit BPH wurden in die Studie eingeschlossen; 51 (25,4%) Patienten hatten ein Prostatavolumen >80cm3 und 150 (74,6%) Patienten ein Volumen 80cm3 stellt die PVP eine durchfĂŒhrbare Therapieoption da
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