40,238 research outputs found
Preliminary evaluation of the role of K2S in MHD hot stream seed recovery
Results are presented for recent analytical and experimental studies of the role of K2S in MHD hot stream seed recovery. The existing thermodynamic data base was found to contain large uncertainties and to be nonexistent for vapor phase K2S. Knudsen cell mass spectrometric experiments were undertaken to determine the vapor species in equilibrium with K2S(c). K atoms and S2 molecules ere found to be the major vapor phase species in vacuum, accounting for greater than 99 percent of the vapor phase. Combustion gas deposition studies using No. 2 Diesel fuel were also undertaken and revealed that condensed phase K2SO3 may potentially be an important compound in the MHD stream at near-stoichiometric combustion
Scaling Laws for Non-Intercommuting Cosmic String Networks
We study the evolution of non-interacting and entangled cosmic string
networks in the context of the velocity-dependent one-scale model. Such
networks may be formed in several contexts, including brane inflation. We show
that the frozen network solution , although generic, is only a
transient one, and that the asymptotic solution is still as in the
case of ordinary (intercommuting) strings, although in the present context the
universe will usually be string-dominated. Thus the behaviour of two strings
when they cross does not seem to affect their scaling laws, but only their
densities relative to the background.Comment: Phys. Rev. D (in press); v2: final published version (references
added, typos corrected
Structural Optimization in automotive design
Although mathematical structural optimization has been an active research area for twenty years, there has been relatively little penetration into the design process. Experience indicates that often this is due to the traditional layout-analysis design process. In many cases, optimization efforts have been outgrowths of analysis groups which are themselves appendages to the traditional design process. As a result, optimization is often introduced into the design process too late to have a significant effect because many potential design variables have already been fixed. A series of examples are given to indicate how structural optimization has been effectively integrated into the design process
The nucleotide sequence of a human immnnoglobulin C-gamma-1 gene
We report the nucleotide sequence of a gene encoding the constant region of a human immnnoglobulin γ1 heavy chain (Cγ1). A comparison of this sequence with those of the Cγ2 and Cγ4 genes reveals that these three human Cγ genes share considerable homology in both coding and noncoding regions. The nucleotide sequence differences indicate that these genes diverged from one another approximately 6–8 million years ago. An examination of hinge exons shows that these coding regions have evolved more rapidly than any other areas of the Cγ genes in terms of both base substitution and deletion–insertion events. Coding sequence diversity also is observed in areas of CH domains which border the hinge
On the origin of noisy states whose teleportation fidelity can be enhanced through dissipation
Recently Badziag \emph{et al.} \cite{badziag} obtained a class of noisy
states whose teleportation fidelity can be enhanced by subjecting one of the
qubits to dissipative interaction with the environment via amplitude damping
channel (ADC). We show that such noisy states result while sharing the states
(| \Phi ^{\pm}> =\frac{1}{\sqrt{2}}(| 00> \pm | 11>)) across ADC. We also show
that under similar dissipative interactions different Bell states give rise to
noisy entangled states that are qualitatively very different from each other in
the sense, only the noisy entangled states constructed from the Bell states (|
\Phi ^{\pm}>) can \emph{}be made better sometimes by subjecting the unaffected
qubit to a dissipative interaction with the environment. Importantly if the
noisy state is non teleporting then it can always be made teleporting with this
prescription. We derive the most general restrictions on improvement of such
noisy states assuming that the damping parameters being different for both the
qubits. However this curious prescription does not work for the noisy entangled
states generated from (| \Psi ^{\pm}> =\frac{1}{\sqrt{2}}(| 01> \pm | 10>)).
This shows that an apriori knowledge of the noisy channel might be helpful to
decide which Bell state needs to be shared between Alice and Bob. \emph{}Comment: Latex, 18 pages: Revised version with a new result. Submitted to PR
Shape optimization of three-dimensional stamped and solid automotive components
The shape optimization of realistic, 3-D automotive components is discussed. The integration of the major parts of the total process: modeling, mesh generation, finite element and sensitivity analysis, and optimization are stressed. Stamped components and solid components are treated separately. For stamped parts a highly automated capability was developed. The problem description is based upon a parameterized boundary design element concept for the definition of the geometry. Automatic triangulation and adaptive mesh refinement are used to provide an automated analysis capability which requires only boundary data and takes into account sensitivity of the solution accuracy to boundary shape. For solid components a general extension of the 2-D boundary design element concept has not been achieved. In this case, the parameterized surface shape is provided using a generic modeling concept based upon isoparametric mapping patches which also serves as the mesh generator. Emphasis is placed upon the coupling of optimization with a commercially available finite element program. To do this it is necessary to modularize the program architecture and obtain shape design sensitivities using the material derivative approach so that only boundary solution data is needed
The Impact of Line Misidentification on Cosmological Constraints from Euclid and other Spectroscopic Galaxy Surveys
We perform forecasts for how baryon acoustic oscillation (BAO) scale and
redshift-space distortion (RSD) measurements from future spectroscopic emission
line galaxy (ELG) surveys such as Euclid are degraded in the presence of
spectral line misidentification. Using analytic calculations verified with mock
galaxy catalogs from log-normal simulations we find that constraints are
degraded in two ways, even when the interloper power spectrum is modeled
correctly in the likelihood. Firstly, there is a loss of signal-to-noise ratio
for the power spectrum of the target galaxies, which propagates to all
cosmological constraints and increases with contamination fraction, .
Secondly, degeneracies can open up between and cosmological parameters.
In our calculations this typically increases BAO scale uncertainties at the
10-20% level when marginalizing over parameters determining the broadband power
spectrum shape. External constraints on , or parameters determining the
shape of the power spectrum, for example from cosmic microwave background (CMB)
measurements, can remove this effect. There is a near-perfect degeneracy
between and the power spectrum amplitude for low values, where
is not well determined from the contaminated sample alone. This has the
potential to strongly degrade RSD constraints. The degeneracy can be broken
with an external constraint on , for example from cross-correlation with a
separate galaxy sample containing the misidentified line, or deeper
sub-surveys.Comment: 18 pages, 7 figures, updated to match version accepted by ApJ (extra
paragraph added at the end of Section 4.3, minor text edits
Supercatalysis
We show that entanglement-assisted transformations of bipartite entangled
states can be more efficient than catalysis [D. Jonathan and M. B. Plenio,
Phys. Rev. Lett. 83, 3566 (1999)}, i.e., given two incomparable bipartite
states not only can the transformation be enabled by performing collective
operations with an auxiliary entangled state, but the entanglement of the
auxiliary state itself can be enhanced. We refer to this phenomenon as
supercatalysis. We provide results on the properties of supercatalysis and its
relationship with catalysis. In particular, we obtain a useful necessary and
sufficient condition for catalysis, provide several sufficient conditions for
supercatalysis and study the extent to which entanglement of the auxiliary
state can be enhanced via supercatalysis.Comment: Latex, 5 page
Calcium-sensing receptor activation increases cell-cell adhesion and ß-cell function
Background/Aims: The extracellular calcium-sensing receptor (CaR) is expressed in pancreatic β-cells where it is thought to facilitate cell-to-cell communication and augment insulin secretion. However, it is unknown how CaR activation improves β-cell function. Methods: Immunocytochemistry and western blotting confirmed the expression of CaR in MIN6 β-cell line. The calcimimetic R568 (1µM) was used to increase the affinity of the CaR and specifically activate the receptor at a physiologically appropriate extracellular calcium concentration. Incorporation of 5-bromo-2’-deoxyuridine (BrdU) was used to measure cell proliferation, whilst changes in non-nutrient-evoked cytosolic calcium were assessed using fura-2-microfluorimetry. AFM-single-cell-force spectroscopy related CaR-evoked changes in epithelial (E)-cadherin expression to improved functional tethering between coupled cells. Results: Activation of the CaR over 48hr doubled the expression of E-cadherin (206±41%) and increased L-type voltage-dependent calcium channel expression by 70% compared to control. These changes produced a 30% increase in cell-cell tethering and elevated the basal-to-peak amplitude of ATP (50µM) and tolbutamide (100µM)-evoked changes in cytosolic calcium. Activation of the receptor also increased PD98059 (1-100µM) and SU1498 (1-100µM)-dependent β-cell proliferation. Conclusion: Our data suggest that activation of the CaR increases E-cadherin mediated functional tethering between β-cells and increases expression of L-type VDCC and secretagogue-evoked changes in [Ca2+]i. These findings could explain how local changes in calcium, co-released with insulin, activate the CaR on neighbouring cells to help ensure efficient and appropriate secretory function
A classical analogue of entanglement
We show that quantum entanglement has a very close classical analogue, namely
secret classical correlations. The fundamental analogy stems from the behavior
of quantum entanglement under local operations and classical communication and
the behavior of secret correlations under local operations and public
communication. A large number of derived analogies follow. In particular
teleportation is analogous to the one-time-pad, the concept of ``pure state''
exists in the classical domain, entanglement concentration and dilution are
essentially classical secrecy protocols, and single copy entanglement
manipulations have such a close classical analog that the majorization results
are reproduced in the classical setting. This analogy allows one to import
questions from the quantum domain into the classical one, and vice-versa,
helping to get a better understanding of both. Also, by identifying classical
aspects of quantum entanglement it allows one to identify those aspects of
entanglement which are uniquely quantum mechanical.Comment: 13 pages, references update
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