1,016 research outputs found
Manifestation of polaronic effects in Josephson currents
Polaronic effects on the Josephson current through a vibrating quantum dot are considered. In the regime of
strong electron–vibron interactions they lead to a power-law suppression of the critical current. This is manifested
in an anomalous temperature dependence of the critical current at temperatures of the order of the polaronic
energy shift
Horava Gravity and Gravitons at a Conformal Point
Recently Horava proposed a renormalizable gravity theory with higher
derivatives by abandoning the Lorenz invariance in UV. Here, I study the Horava
model at , where an anisotropic Weyl symmetry exists in the UV
limit, in addition to the foliation-preserving diffeomorphism. By considering
linear perturbations around Minkowski vacuum, I show that the scalar graviton
mode is completely disappeared and only the usual tensor graviton modes remain
in the physical spectrum. The existence of the UV conformal symmetry is unique
to the theory with the detailed balance and it is quite probable that
be the UV fixed point. This situation is analogous to
, which is Lorentz invariant in the IR limit and is believed to be
the IR fixed point.Comment: Added comments and references, Accepted in GER
Bundle and annulus CHF correlations applicable for near critical pressure region
Paper presented at the 8th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Mauritius, 11-13 July, 2011.Bundle and annulus CHF correlations are developed by
using CHF experimental data from the Freon R-134a Thermal
Hydraulic Experimental Loop developed at KAERI. The CHF
data are in the range of the pressure of 3200 ~ 4030 kPa
(Critical pressure of R-134a = 4059 kPa), the mass flux
150∼1500 kg/m2s, and the inlet subcooling 40 ~ 70 kJ/kg. We
obtained local T/H values using a subchannel analysis code and
produced CHF correlations for the matrix subchannel, coldwall
subchannel and annulus channel, respectively. A
subchannel code, The MATRA-α IBM PC version, is used to
obtain the local conditions in a hot subchannel (CHF observed
channel) in the 5x5 bundle geometry. All the CHF experimental
data are successfully calculated by the present correlations with
good prediction performance. The prediction accuracy of the
correlations is not distorted by much in any of the ranges of the
independent parameters. The bundle CHF correlations could
help one to conceptually design a SCWR, by adopting a fluidto-
fluid modeling technique for a CHF near a critical pressure.mp201
Nanomechanics of a magnetic shuttle device
We show that self sustained mechanical vibrations in a model magnetic shuttle device can be driven by both
the charge and the spin accumulated on the movable central island of the device. Different scenarios for how
spin- and charge-induced shuttle instabilities may develop are discussed and shown to depend on whether there
is a Coulomb blockade of tunneling or not. The crucial role of electronic spin flips in a magnetically driven shuttle
is established and shown to cause giant magnetoresistance and dynamic magnetostriction effects
The Phonon Drag Effect in Single-Walled Carbon Nanotubes
A variational solution of the coupled electron-phonon Boltzmann equations is
used to calculate the phonon drag contribution to the thermopower in a 1-D
system. A simple formula is derived for the temperature dependence of the
phonon drag in metallic, single-walled carbon nanotubes. Scattering between
different electronic bands yields nonzero values for the phonon drag as the
Fermi level varies.Comment: 8 pages, 4 figure
Measurement of Trace I-129 Concentrations in CsI Powder and Organic Liquid Scintillator with Accelerator Mass Spectrometry
Levels of trace radiopurity in active detector materials is a subject of
major concern in low-background experiments. Procedures were devised to measure
trace concentrations of I-129 in the inorganic salt CsI as well as in organic
liquid scintillator with Accelerator Mass Spectrometry (AMS) which leads to
improvement in sensitivities by several orders of magnitude over other methods.
No evidence of their existence in these materials were observed. Limits of < 6
X 10^{-13} g/g and < 2.6 X 10^{-17} g/g on the contaminations of I-129 in CsI
and liquid scintillator, respectively, were derived.These are the first results
in a research program whose goals are to develop techniques to measure trace
radioactivity in detector materials by AMS.Comment: Proceedings of 10th International Conference on Accelerator Mass
Spectrometr
Interactions between proteins bound to biomembranes
We study a physical model for the interaction between general inclusions
bound to fluid membranes that possess finite tension, as well as the usual
bending rigidity. We are motivated by an interest in proteins bound to cell
membranes that apply forces to these membranes, due to either entropic or
direct chemical interactions. We find an exact analytic solution for the
repulsive interaction between two similar circularly symmetric inclusions. This
repulsion extends over length scales of order tens of nanometers, and contrasts
with the membrane-mediated contact attraction for similar inclusions on
tensionless membranes. For non circularly symmetric inclusions we study the
small, algebraically long-ranged, attractive contribution to the force that
arises. We discuss the relevance of our results to biological phenomena, such
as the budding of caveolae from cell membranes and the striations that are
observed on their coats.Comment: 22 pages, 2 figure
On the gauge and BRST invariance of the chiral QED with Faddeevian anomaly
Chiral Schwinger model with the Faddeevian anomaly is considered. It is found
that imposing a chiral constraint this model can be expressed in terms of
chiral boson. The model when expressed in terms of chiral boson remains
anomalous and the Gauss law of which gives anomalous Poisson brackets between
itself. In spite of that a systematic BRST quantization is possible. The
Wess-Zumino term corresponding to this theory appears automatically during the
process of quantization. A gauge invariant reformulation of this model is also
constructed. Unlike the former one gauge invariance is done here without any
extension of phase space. This gauge invariant version maps onto the vector
Schwinger model.The gauge invariant version of the chiral Schwinger model for
has a massive field with identical mass however gauge invariant version
obtained here does not map on to that.Comment: 11 pages latex, no figures, A little change in Title and abstrac
Expression profiling of cyclin B1 and D1 in cervical carcinoma
Aim: Cyclins are a family of regulatory proteins that play a key role in controlling the cell cycle. Abnormalities of cell cycle regulators, including cyclins and cyclin dependent kinases, have been reported in various malignant tumors. This study was undertaken to quantitatively detect cyclin B1 and D1 in cervical cancer. Methods: A quantitative real-time reverse transcription polymerase chain reaction and Western blot assay were used to analyze the expression of cyclin B1/D1 mRNA and proteins, respectively, in fresh invasive cervical cancer (n = 41) and normal cervical tissues (n = 10). Results: There was significantly greater cyclin B1 expression in invasive cervical cancer than in normal cervical tissue (P = 0.019). However, cyclin D1 expression was not significantly different. A Western blot assay yielded similar results. Conclusion: Our results were consistent with the concept that up-regulation of cyclin B1 expression occurred in cervical cancer and an aberrant expression of cyclin B1 might play an important role in cervical carcinogenesis.Цель: циклины представляют собой семейство регуляторных белков, контролирующих клеточный цикл. Наличие
функциональных и структурных нарушений регуляторов клеточного цикла (циклинов и циклинзависимых киназ) было
отмечено в клетках различных злокачественных новообразований. Целью данного исследования было проведение
количественного определения циклинов B1 и D1 в клетках рака шейки матки. Методы: определение уровня экспрессии
циклинов B1/D1 (mRNA и белков соответственно) в свежеполученных клетках инвазивного рака шейки матки (n = 41) и
нормальной ткани шейки матки (n = 10) проводили методами RT-PCR в режиме реального времени и Вестерн-блот анализа.
Результаты: отмечен более высокий уровень экспрессии гена циклина В1 в клетках инвазивного рака шейки матки, чем в
клетках нормальной ткани (P = 0,019). Не выявлены значительные различия в уровне экспрессии гена циклина D1. При
Вестерн-блот анализе получены аналогичные результаты. Выводы: результаты исследования подтверждают концепцию
об активации экспрессии циклина В1 при раке шейки матки. Аберрантная экспрессия циклина В1 может играть важную
роль при злокачественной трансформации эпителия шейки матки
Extremal black holes in the Ho\v{r}ava-Lifshitz gravity
We study the near-horizon geometry of extremal black holes in the
Ho\v{r}ava-Lifshitz gravity with a flow parameter . For ,
near-horizon geometry of extremal black holes are AdS with
different radii, depending on the (modified) Ho\v{r}ava-Lifshitz gravity. For
, the radius of is negative, which means
that the near-horizon geometry is ill-defined and the corresponding
Bekenstein-Hawking entropy is zero. We show explicitly that the entropy
function approach does not work for obtaining the Bekenstein-Hawking entropy of
extremal black holes.Comment: 18 pages, v2:some points on Lifshitz black holes claified, v3:
version to appear in EJP
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