257 research outputs found
Multiple D-branes as a D-brane
From BFSS matrix theory considerations, it is expected that a single
D-brane action can be obtained from N D-brane action in large N
limit. We examine and confirm this expectation by working out the details of
DBI and Chern-Simons terms of D-brane action from D-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
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
A generic class of string theories predicts the existence of light moduli
fields, and they are expected to have masses comparable to the
gravitino mass which is in a range of 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 keV 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 keV 500keV to survive the constraints. It is also stressed that
the moduli can be dark matter in our universe for the mass region keV
100keV.Comment: A few changes in section IV and
Adjoint Messengers and Perturbative Unification at the String Scale
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
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
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
The dilaton field in string theories (if exists) is expected to have a mass
of the order of the gravitino mass which is in a range of
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()-ray
backgrounds. This excludes an interesting mass region, , 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
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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