7,890 research outputs found
Bounds of Efficiency at Maximum Power for Normal-, Sub- and Super-Dissipative Carnot-Like Heat Engines
The Carnot-like heat engines are classified into three types (normal-, sub-
and super-dissipative) according to relations between the minimum irreversible
entropy production in the "isothermal" processes and the time for completing
those processes. The efficiencies at maximum power of normal-, sub- and
super-dissipative Carnot-like heat engines are proved to be bounded between
and , and , 0 and
, respectively. These bounds are also shared by linear, sub-
and super-linear irreversible Carnot-like engines [Tu and Wang, Europhys. Lett.
98, 40001 (2012)] although the dissipative engines and the irreversible ones
are inequivalent to each other.Comment: 1 figur
On Kernel Formulas and Dispersionless Hirota Equations
We rederive dispersionless Hirota equations of the dispersionless Toda
hierarchy from the method of kernel formula provided by Carroll and Kodama. We
then apply the method to derive dispersionless Hirota equations of the extended
dispersionless BKP(EdBKP) hierarchy proposed by Takasaki. Moreover, we verify
associativity equations (WDVV equations) in the EdBKP hierarchy from
dispersionless Hirota equations and give a realization of associative algebra
with structure constants expressed in terms of residue formula.Comment: 30 pages, minor corrections, references adde
Deranged calcium signaling and neurodegeneration in spinocerebellar ataxia type 3
Spinocerebellar ataxia type 3 (SCA3), also known as Machado-Joseph disease (MJD), is
an autosomal-dominant neurodegenerative disorder caused by a polyglutamine
expansion in ataxin-3 (SCA3, MJD1) protein. In biochemical experiments we demonstrate
that mutant SCA3exp specifically associated with the type 1 inositol 1,4,5-trisphosphate
receptor (InsP3R1), an intracellular calcium (Ca2+) release channel. In electrophysiological
and Ca2+ imaging experiments we show that InsP3R1 are sensitized to activation by InsP3
in the presence of mutant SCA3exp. We found that feeding SCA3-YAC-84Q transgenic
mice with dantrolene, a clinically relevant stabilizer of intracellular Ca2+ signaling,
improved their motor performance and prevented neuronal cells loss in pontine nuclei
and substantia nigra regions. Our results indicate that deranged Ca2+ signaling may play
an important role in SCA3 pathology and that Ca2+ signaling stabilizers such as
dantrolene may be considered as potential therapeutic drugs for treatment of SCA3
patients
Computation of flow behind three side-by-side cylinders of unequal/equal spacing
This paper aims to simulate unstable gap flows of three side-by-side cylinders unequally/equally spaced at T1/d = 1.5 and T2/d = 1.6 in a uniform cross flow (Re=300). The simulation is carried out using ANSYS Flotran 7.0. A mesh-independent study is conducted on a single cylinder at Re=100. The Strouhal number and wake flow characteristics compare well with experimental results. Simulation of three side-by-side cylinders in uniform cross flow has revealed that the gap flows are unstable and constantly re-orientating, which has the effect of restructuring the wake flows behind the cylinders. The flow field for unequal spacing of the cylinders is similar to the equal spacing case for some period of time with a symmetrical near wake. However, at other times, the wake flow is asymmetrical. This agrees well with the visualisation of Wang et al. (2002), in which the gap flows and the wake flow are constantly in transition
Conformal Covariantization of Moyal-Lax Operators
A covariant approach to the conformal property associated with Moyal-Lax
operators is given. By identifying the conformal covariance with the second
Gelfand-Dickey flow, we covariantize Moyal-Lax operators to construct the
primary fields of one-parameter deformation of classical -algebras.Comment: 13 pages, Revtex, no figures, v.2: typos corrected, references added
and conclusion modifie
Bounds of efficiency at maximum power for linear, superlinear and sublinear irreversible Carnot-like heat engines
The efficiency at maximum power (EMP) of irreversible Carnot-like heat
engines is investigated based on the weak endoreversible assumption and the
phenomenologically irreversible thermodynamics. It is found that the weak
endoreversible assumption can reduce to the conventional one for the heat
engines working at maximum power. Carnot-like heat engines are classified into
three types (linear, superlinear, and sublinear) according to different
characteristics of constitutive relations between the heat transfer rate and
the thermodynamic force. The EMPs of Carnot-like heat engines are proved to be
bounded between and for the linear type, 0 and
for the superlinear type, and and for
the sublinear type, respectively, where is the Carnot efficiency.Comment: 6 journal pages, 1 figure, EPL (in press
Recurrent chronic subdural hemorrhage due to cervical spinal CSF leak in a young adult: Report of a case
SummaryNontraumatic intracranial subdural hemorrhage may result from disorders at remote anatomic sites. Here, we report a young adult who suffered from bilateral subdural hematoma without antecedent head injury. The subdural hematoma did not resolve after surgical drainage. The symptom of postural headache prompted a contrast-enhanced magnetic resonance imaging (MRI) examination of the brain, which revealed signs indicative of intracranial hypotension. Subsequently, MRI of the spine demonstrated leakage of cerebrospinal fluid (CSF) in the upper cervical spine region. The patient recovered after conservative treatment. A review of the patient’s medical history revealed that the patient had chiropractic therapy on his neck 2 months prior to admission. Intracranial hypotension due to spinal CSF leak is a rare cause of subdural hemorrhage, yet it should be considered in the absence of head trauma
A model-based circular binary segmentation algorithm for the analysis of array CGH data
<p>Abstract</p> <p>Background</p> <p>Circular Binary Segmentation (CBS) is a permutation-based algorithm for array Comparative Genomic Hybridization (aCGH) data analysis. CBS accurately segments data by detecting change-points using a maximal-<it>t </it>test; but extensive computational burden is involved for evaluating the significance of change-points using permutations. A recent implementation utilizing a hybrid method and early stopping rules (hybrid CBS) to improve the performance in speed was subsequently proposed. However, a time analysis revealed that a major portion of computation time of the hybrid CBS was still spent on permutation. In addition, what the hybrid method provides is an approximation of the significance upper bound or lower bound, not an approximation of the significance of change-points itself.</p> <p>Results</p> <p>We developed a novel model-based algorithm, extreme-value based CBS (eCBS), which limits permutations and provides robust results without loss of accuracy. Thousands of aCGH data under null hypothesis were simulated in advance based on a variety of non-normal assumptions, and the corresponding maximal-<it>t </it>distribution was modeled by the Generalized Extreme Value (GEV) distribution. The modeling results, which associate characteristics of aCGH data to the GEV parameters, constitute lookup tables (eXtreme model). Using the eXtreme model, the significance of change-points could be evaluated in a constant time complexity through a table lookup process.</p> <p>Conclusions</p> <p>A novel algorithm, eCBS, was developed in this study. The current implementation of eCBS consistently outperforms the hybrid CBS 4× to 20× in computation time without loss of accuracy. Source codes, supplementary materials, supplementary figures, and supplementary tables can be found at <url>http://ntumaps.cgm.ntu.edu.tw/eCBSsupplementary</url>.</p
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