257 research outputs found

    Multiple Dp_p-branes as a Dp+2_{p+2}-brane

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    From BFSS matrix theory considerations, it is expected that a single Dp+2_{p+2}-brane action can be obtained from N Dp_p-brane action in large N limit. We examine and confirm this expectation by working out the details of DBI and Chern-Simons terms of Dp+2_{p+2}-brane action from Dp_{p}-brane action. We show that the same relation works for non-BPS, as well as BPS branesComment: 14 page

    On the Moduli Problem and Baryogenesis in Gauge-mediated SUSY Breaking Models

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    We investigate whether the Affleck-Dine mechanism can produce sufficient baryon number of the universe in the gauge-mediated SUSY breaking models, while evading the cosmological moduli problem by late-time entropy production. We find that the Q-ball formation renders the scenario very difficult to work, irrespective of the detail mechanism of the entropy production.Comment: 11 pages, RevTeX, 5 postscript figures include

    Cosmological Moduli Problem in Gauge-mediated Supersymmetry Breaking Theories

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    A generic class of string theories predicts the existence of light moduli fields, and they are expected to have masses mϕm_\phi comparable to the gravitino mass m3/2m_{3/2} which is in a range of 10210^{-2}keV--1GeV in gauge-mediated supersymmetry breaking theories. Such light fields with weak interactions suppressed by the Planck scale can not avoid some stringent cosmological constraints, that is, they suffer from `cosmological moduli problems'. We show that all the gravitino mass region 10210^{-2}keV m3/2\lesssim m_{3/2} \lesssim 1GeV is excluded by the constraints even if we incorporate a late-time mini-inflation (thermal inflation). However, a modification of the original thermal inflation model enables the region 10210^{-2}keV m3/2\lesssim m_{3/2} \lesssim 500keV to survive the constraints. It is also stressed that the moduli can be dark matter in our universe for the mass region 10210^{-2}keV mϕ\lesssim m_\phi \lesssim 100keV.Comment: A few changes in section IV and

    Adjoint Messengers and Perturbative Unification at the String Scale

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    We consider states in the adjoint representation of the Standard Model gauge group as messengers for mediation of supersymmetry (SUSY) breaking. These new messengers can shift the gauge coupling unification to the string scale at O(5x10^{17} GeV) if their masses are at O(10^{14} GeV). The predicted SUSY mass spectrum at the electroweak scale is significantly different from those in other gauge-mediated or supergravity models, resulting in robust mass relations. The gravitino mass is predicted to be about 1-10 GeV. The heavy messenger sector could provide a superheavy dark matter candidate.Comment: 9 pages, 2 figure

    The evaluation of surgical factors related to recovery period of upper lip hypoaesthesia after Le Fort I osteotomy

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    金沢大学医薬保健研究域医学系Purpose: It is unclear whether surgical factors can affect the upper lip sensitivity. The aim of this study was to assess the factors that can affect the recovery period of hypoaesthesia of the upper lip after Le Fort I osteotomy, using trigeminal somatosensory evoked potential (TSEP) objectively. Patients and methods: Twenty-nine patients with mandibular prognathism underwent Le Fort I osteotomy with and without artificial pterygoid plate fracture. Trigeminal nerve hypoaesthesia at the region of the upper lip was assessed bilaterally by the TSEP method. The distance between the infraorbital foramen and the osteotomy line (IO) or the nearest plate/screw position (IP) was measured on three-dimensional computed tomography (CT). The relationship between the recovery period in upper lip hypoaesthesia and surgical factors (these distances, movement amount, pterygoid plate fracture) were analysed statistically. Results: The recovery period in upper lip hypoaesthesia did not significantly correlate with IO, IP and movement amount. There was no significant difference between pterygoid plate fracture group and non-fracture group. Conclusion: Temporary hypoaesthesia of upper lip after Le Fort I osteotomy could not be avoided, however, osteotomy line, plate/screw position and pterygoid plate fracture in Le Fort I osteotomy did not affect the recovery period of upper lip hypoaesthesia with TSEP. © 2008 European Association for Cranio-Maxillofacial Surgery.This article has not been published yet

    Isolated quantum dot in application to terahertz photon counting

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    We present an experimental study of a large quantum dot (QD) capacitively coupled to an aluminum single electron transistor (SET) and irradiated with terahertz radiation from a blackbody source. The SET is used as a noninvasive electrometer sensitive to a single-charge fluctuation on the QD. Qualitatively different regimes of QD confinement have been identified from the SET response. We demonstrate that the state of a nearly isolated QD can potentially be used for counting individual terahertz photons. © 2006 The American Physical Society

    Cosmological Constraint on the String Dilaton in Gauge-mediated Supersymmetry Breaking Theories

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    The dilaton field in string theories (if exists) is expected to have a mass of the order of the gravitino mass m3/2m_{3/2} which is in a range of 10210^{-2}keV--1GeV in gauge-mediated supersymmetry breaking models. If it is the case, the cosmic energy density of coherent dilaton oscillation easily exceeds the critical density of the present universe. We show that even if this problem is solved by a late-time entropy production (thermal inflation) a stringent constraint on the energy density of the dilaton oscillation is derived from experimental upperbounds on the cosmic X(γ\gamma)-ray backgrounds. This excludes an interesting mass region, 500keVm3/21GeV500keV \lesssim m_{3/2} \lesssim 1GeV, in gauge-mediated supersymmetry breaking models.Comment: 13 pages (RevTex file including one figure, use psfig), revised version to be published in Physical Review Letter

    Electrogramas auriculares endocárdicos anormales en pacientes de la tercera edad con fibrilación auricular paroxística idiopática

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    Los pacientes de la tercera edad están particularmente predispuestos a desarrollar episodios de fibrilación auricular paroxística (FAP), pudiendo ser los cambios que experimenta el miocardio auricular un factor contribuyente a la aparición de este fenómeno con el correr de los años. Por ende, diseñamos este trabajo con la idea de investigar los cambios que se producen en los electrogramas auriculares endocárdicos registrados por medio de un mapeo intraauricular con catéter en pacientes con FAP idiopática en la tercera edad. Realizamos un mapeo endocárdico con catéter de la aurícula derecha en ritmo sinusal en 72 pacientes con FAP idiopática para evaluar la influencia de la edad avanzada en los electrogramas auriculares endocárdicos. Los electrogramas bipolares fueron registrados de 12 sitios de la aurícula derecha, y un electrograma endocárdico auricular anormal fue definido como aquel que posee una duración ≥100 ms, y/o 8 o más deflexiones fragmentadas. Se registraron 864 electrogramas auriculares endocárdicos que fueron analizados cuantitativamente. El número de electrogramas auriculares anormales, así como la máxima duración y el mayor número de deflexiones fragmentadas de los electrogramas auriculares endocárdicos en los pacientes con FAP idiopática tuvo una correlación significativamente positiva con la edad. Se observó que la edad avanzada altera las propiedades electrofisiológicas del miocardio auricular haciéndolo más susceptible a desarrollar episodios de FAP. Estos cambios electrofisiológicos son más extensos conforme aumenta la edad. Existe un aumento progresivo en la extensión de la anormalidad electrofisiológica del miocardio auricular en pacientes de la tercera edad con fibrilación auricular paroxística idiopática
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