10,151 research outputs found
Mars spacecraft power system development Interim report
Modified Mariner power system design for Mars mission
High-Frequency Spin Waves in YBa2Cu3O6.15
Pulsed neutron spectroscopy is used to make absolute measurements of the
dynamic magnetic susceptibility of insulating YBa2Cu3O6.15. Acoustic and
optical modes, derived from in- and out-of-phase oscillation of spins in
adjacent CuO2 planes, dominate the spectra and are observed up to 250 meV. The
optical modes appear first at 74 meV. Linear-spin-wave theory gives an
excellent description of the data and yields intra- and inter-layer exchange
constants of J_parallel =125 meV and J_perp = 11 meV respectively and a
spin-wave intensity renormalization Z_chi = 0.4.Comment: postscript, 11 pages, 4 figures, Fig.2 fixe
Mean field for performance models with generally distributed-timed transitions
In this paper we extend the mean-field limit of a class of
stochastic models with exponential and deterministic delays to include
exponential and generally-distributed delays. Our main focus is the rigorous
proof of the mean-field limit
Mean field for performance models with generally distributed-timed transitions
In this paper we extend the mean-field limit of a class of
stochastic models with exponential and deterministic delays to include
exponential and generally-distributed delays. Our main focus is the rigorous
proof of the mean-field limit
The Clergy of Early Seventeenth-Century France: Self-Perception and Society\u27s Perception
To understand the nature of the seventeenth-century French church, one must understand the rural clergy and their parishioners; the majority of the population was rural. One glimpse of how the clergy perceived themselves and how others viewed them is given in the cahiers de doleances prepared by each estate for the Estates General of 1614. The article also explores the First Estate’s role in society and the reformation of the clergy proposed by all three estates. The elite are best represented in the cahiers of the First and Third Estates, while a cross-section of the Second Estate is represented. Nonetheless, J.M. Hayden and Malcolm Greenshields argue that it is a good source of knowledge about public opinion. The First Estate acknowledged a pressing need for reform within the cahiers, but only of rural clergy, and it wanted to control the process. The other two estates argued for reform of the entire First Estate, with greater involvement from the laity. Specific problems, abuses, ecclesiastical privileges, and reforms are described. Each estate had different expectations of the clergy’s qualifications and service, which are discussed
Calcific uremic arteriolopathy: Pathophysiology, reactive oxygen species and therapeutic approaches
Calcific uremic arteriolopathy (CUA)/calciphylaxis is an important cause of morbidity and mortality in patients with chronic kidney disease requiring renal replacement. Once thought to be rare, it is being increasingly recognized and reported on a global scale. The uremic milieu predisposes to multiple metabolic toxicities including increased levels of reactive oxygen species and inflammation. Increased oxidative stress and inflammation promote this arteriolopathy by adversely affecting endothelial function resulting in a prothrombotic milieu and significant remodeling effects on vascular smooth muscle cells. These arteriolar pathological effects include intimal hyperplasia, inflammation, endovascular fibrosis and vascular smooth muscle cell apoptosis and differentiation into bone forming osteoblast-like cells resulting in medial calcification. Systemic factors promoting this vascular condition include elevated calcium, parathyroid hormone and hyperphosphatemia with consequent increases in the calcium × phosphate product. The uremic milieu contributes to a marked increased in upstream reactive oxygen species—oxidative stress and subsequent downstream increased inflammation, in part, via activation of the nuclear transcription factor NFκB and associated downstream cytokine pathways. Consitutive anti-calcification proteins such as Fetuin-A and matrix GLA proteins and their signaling pathways may be decreased, which further contributes to medial vascular calcification. The resulting clinical entity is painful, debilitating and contributes to the excess morbidity and mortality associated with chronic kidney disease and end stage renal disease. These same histopathologic conditions also occur in patients without uremia and therefore, the term calcific obliterative arteriolopathy could be utilized in these conditions
Decoupling with unitary approximate two-designs
Consider a bipartite system, of which one subsystem, A, undergoes a physical
evolution separated from the other subsystem, R. One may ask under which
conditions this evolution destroys all initial correlations between the
subsystems A and R, i.e. decouples the subsystems. A quantitative answer to
this question is provided by decoupling theorems, which have been developed
recently in the area of quantum information theory. This paper builds on
preceding work, which shows that decoupling is achieved if the evolution on A
consists of a typical unitary, chosen with respect to the Haar measure,
followed by a process that adds sufficient decoherence. Here, we prove a
generalized decoupling theorem for the case where the unitary is chosen from an
approximate two-design. A main implication of this result is that decoupling is
physical, in the sense that it occurs already for short sequences of random
two-body interactions, which can be modeled as efficient circuits. Our
decoupling result is independent of the dimension of the R system, which shows
that approximate 2-designs are appropriate for decoupling even if the dimension
of this system is large.Comment: Published versio
On black hole thermalization, D0 brane dynamics, and emergent spacetime
When matter falls past the horizon of a large black hole, the expectation
from string theory is that the configuration thermalizes and the information in
the probe is rather quickly scrambled away. The traditional view of a classical
unique spacetime near a black hole horizon conflicts with this picture. The
question then arises as to what spacetime does the probe actually see as it
crosses a horizon, and how does the background geometry imprint its signature
onto the thermal properties of the probe. In this work, we explore these
questions through an extensive series of numerical simulations of D0 branes. We
determine that the D0 branes quickly settle into an incompressible symmetric
state -- thermalized within a few oscillations through a process driven
entirely by internal non-linear dynamics. Surprisingly, thermal background
fluctuations play no role in this mechanism. Signatures of the background
fields in this thermal state arise either through fluxes, i.e. black hole hair;
or if the probe expands to the size of the horizon -- which we see evidence of.
We determine simple scaling relations for the D0 branes' equilibrium size, time
to thermalize, lifetime, and temperature in terms of their number, initial
energy, and the background fields. Our results are consistent with the
conjecture that black holes are the fastest scramblers as seen by Matrix
theory.Comment: 43 pages, 12 figures; v2: added analysis showing that results are
consistent with and confirm Susskind conjecture on black hole thermalization.
Added clarification about strong coupling regime. Citation adde
Entanglement measures and approximate quantum error correction
It is shown that, if the loss of entanglement along a quantum channel is
sufficiently small, then approximate quantum error correction is possible,
thereby generalizing what happens for coherent information. Explicit bounds are
obtained for the entanglement of formation and the distillable entanglement,
and their validity naturally extends to other bipartite entanglement measures
in between. Robustness of derived criteria is analyzed and their tightness
compared. Finally, as a byproduct, we prove a bound quantifying how large the
gap between entanglement of formation and distillable entanglement can be for
any given finite dimensional bipartite system, thus providing a sufficient
condition for distillability in terms of entanglement of formation.Comment: 7 pages, two-columned revtex4, no figures. v1: Deeply revised and
extended version: different entanglement measures are separately considered,
references are added, and some remarks are stressed. v2: Added a sufficient
condition for distillability in terms of entanglement of formation; published
versio
Quantum correlations in the temporal CHSH scenario
We consider a temporal version of the CHSH scenario using projective
measurements on a single quantum system. It is known that quantum correlations
in this scenario are fundamentally more general than correlations obtainable
with the assumptions of macroscopic realism and non-invasive measurements. In
this work, we also educe some fundamental limitations of these quantum
correlations. One result is that a set of correlators can appear in the
temporal CHSH scenario if and only if it can appear in the usual spatial CHSH
scenario. In particular, we derive the validity of the Tsirelson bound and the
impossibility of PR-box behavior. The strength of possible signaling also turns
out to be surprisingly limited, giving a maximal communication capacity of
approximately 0.32 bits. We also find a temporal version of Hardy's nonlocality
paradox with a maximal quantum value of 1/4.Comment: corrected versio
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