366 research outputs found
Fast Quantum Modular Exponentiation
We present a detailed analysis of the impact on modular exponentiation of
architectural features and possible concurrent gate execution. Various
arithmetic algorithms are evaluated for execution time, potential concurrency,
and space tradeoffs. We find that, to exponentiate an n-bit number, for storage
space 100n (twenty times the minimum 5n), we can execute modular exponentiation
two hundred to seven hundred times faster than optimized versions of the basic
algorithms, depending on architecture, for n=128. Addition on a neighbor-only
architecture is limited to O(n) time when non-neighbor architectures can reach
O(log n), demonstrating that physical characteristics of a computing device
have an important impact on both real-world running time and asymptotic
behavior. Our results will help guide experimental implementations of quantum
algorithms and devices.Comment: to appear in PRA 71(5); RevTeX, 12 pages, 12 figures; v2 revision is
substantial, with new algorithmic variants, much shorter and clearer text,
and revised equation formattin
Working with bipolar disorder during the covid-19 pandemic: Both crisis and opportunity
© 2020, WikiJournal User Group. All rights reserved. Beyond public health and economic costs, the COVID-19 pandemic adds strain, disrupts daily routines, and com-plicates mental health and medical service delivery for those with mental health and medical conditions. Bipolar disorder can increase vulnerability to infection; it can also enhance stress, complicate treatment, and heighten interpersonal stigma. Yet there are successes when people proactively improve social connections, prioritize self-care, and learn to use mobile and telehealth effectively
Modeling Gravitational Recoil Using Numerical Relativity
We review the developments in modeling gravitational recoil from merging
black-hole binaries and introduce a new set of 20 simulations to test our
previously proposed empirical formula for the recoil. The configurations are
chosen to represent generic binaries with unequal masses and precessing spins.
Results of these simulations indicate that the recoil formula is accurate to
within a few km/s in the similar mass-ratio regime for the out-of-plane recoil.Comment: corrections to text, 11 pages, 1 figur
Security governance and networks: New theoretical perspectives in transatlantic security
The end of the Cold War has not only witnessed the rise of new transnational threats such as terrorism, crime, proliferation and civil war; it has also seen the growing role of non-state actors in the provision of security in Europe and North America. Two concepts in particular have been used to describe these transformations: security governance and networks. However, the differences and potential theoretical utility of these
two concepts for the study of contemporary security have so far been under-examined. This article seeks to address this gap. It proposes that security governance can help to explain the transformation of Cold War security structures, whereas network analysis is particularly useful for understanding the relations and interactions between public and private actors in the making and implementation of national and international security policies
Complement Is Activated During Normothermic Machine Perfusion of Porcine and Human Discarded Kidneys
Background: The gap between demand and supply of kidneys for transplantation
necessitates the use of kidneys from extended criteria donors. Transplantation of these
donor kidneys is associated with inferior results, reflected by an increased risk of delayed
graft function. Inferior results might be explained by the higher immunogenicity of
extended criteria donor kidneys. Normothermic machine perfusion (NMP) could be
used as a platform to assess the quality and function of donor kidneys. In addition, it
could be useful to evaluate and possibly alter the immunological response of donor
kidneys. In this study, we first evaluated whether complement was activated during NMP
of porcine and human discarded kidneys. Second, we examined the relationship between
complement activation and pro-inflammatory cytokines during NMP. Third, we assessed
the effect of complement activation on renal function and injury during NMP of porcine
kidneys. Lastly, we examined local complement C3d deposition in human renal biopsies
after NMP.
Methods: NMP with a blood-based perfusion was performed with both porcine and
discarded human kidneys for 4 and 6 h, respectively. Perfusate samples were taken every
hour to assess complement activation, pro-inflammatory cytokines and renal function.
Biopsies were taken to assess histological injury and complement deposition.
Results: Complement activation products C3a, C3d, and soluble C5b-9 (sC5b-9) were
found in perfusate samples taken during NMP of both porcine and human kidneys. In
addition, complement perfusate levels positively correlated with the cytokine perfusate
levels of IL-6, IL-8, and TNF during NMP of porcine kidneys. Porcine kidneys with high
sC5b-9 perfusate levels had significantly lower creatinine clearance after 4 h of NMP. In line with these findings, high complement perfusate levels were seen during NMP of
human discarded kidneys. In addition, kidneys retrieved from brain-dead donors had
significantly higher complement perfusate levels during NMP than kidneys retrieved from
donors after circulatory death.
Conclusion: Normothermic kidney machine perfusion induces complement activation in
porcine and human kidneys, which is associated with the release of pro-inflammatory
cytokines and in porcine kidneys with lower creatinine clearance. Complement inhibition
during NMP might be a promising strategy to reduce renal graft injury and improve graft
function prior to transplantation
Path Selection for Quantum Repeater Networks
Quantum networks will support long-distance quantum key distribution (QKD)
and distributed quantum computation, and are an active area of both
experimental and theoretical research. Here, we present an analysis of
topologically complex networks of quantum repeaters composed of heterogeneous
links. Quantum networks have fundamental behavioral differences from classical
networks; the delicacy of quantum states makes a practical path selection
algorithm imperative, but classical notions of resource utilization are not
directly applicable, rendering known path selection mechanisms inadequate. To
adapt Dijkstra's algorithm for quantum repeater networks that generate
entangled Bell pairs, we quantify the key differences and define a link cost
metric, seconds per Bell pair of a particular fidelity, where a single Bell
pair is the resource consumed to perform one quantum teleportation. Simulations
that include both the physical interactions and the extensive classical
messaging confirm that Dijkstra's algorithm works well in a quantum context.
Simulating about three hundred heterogeneous paths, comparing our path cost and
the total work along the path gives a coefficient of determination of 0.88 or
better.Comment: 12 pages, 8 figure
Method to estimate ISCO and ring-down frequencies in binary systems and consequences for gravitational wave data analysis
Recent advances in the description of compact binary systems have produced
gravitational waveforms that include inspiral, merger and ring-down phases.
Comparing results from numerical simulations with those of post-Newtonian (PN),
and related, expansions has provided motivation for employing PN waveforms in
near merger epochs when searching for gravitational waves and has encouraged
the development of analytic fits to full numerical waveforms. The models and
simulations do not yet cover the full binary coalescence parameter space. For
these yet un-simulated regions, data analysts can still conduct separate
inspiral, merger and ring-down searches. Improved knowledge about the end of
the inspiral phase, the beginning of the merger, and the ring-down frequencies
could increase the efficiency of both coherent inspiral-merger-ring-down (IMR)
searches and searches over each phase separately. Insight can be gained for all
three cases through a recently presented theoretical calculation, which,
corroborated by the numerical results, provides an implicit formula for the
final spin of the merged black holes, accurate to within 10% over a large
parameter space. Knowledge of the final spin allows one to predict the end of
the inspiral phase and the quasinormal mode ring-down frequencies, and in turn
provides information about the bandwidth and duration of the merger. In this
work we will discuss a few of the implications of this calculation for data
analysis.Comment: Added references to section 3 14 pages 5 figures. Submitted to
Classical and Quantum Gravit
Exact boundary conditions in numerical relativity using multiple grids: scalar field tests
Cauchy-Characteristic Matching (CCM), the combination of a central 3+1 Cauchy
code with an exterior characteristic code connected across a time-like
interface, is a promising technique for the generation and extraction of
gravitational waves. While it provides a tool for the exact specification of
boundary conditions for the Cauchy evolution, it also allows to follow
gravitational radiation all the way to infinity, where it is unambiguously
defined.
We present a new fourth order accurate finite difference CCM scheme for a
first order reduction of the wave equation around a Schwarzschild black hole in
axisymmetry. The matching at the interface between the Cauchy and the
characteristic regions is done by transfering appropriate characteristic/null
variables. Numerical experiments indicate that the algorithm is fourth order
convergent. As an application we reproduce the expected late-time tail decay
for the scalar field.Comment: 14 pages, 5 figures. Included changes suggested by referee
Six-month outcomes from a randomized trial augmenting serotonin reuptake inhibitors with exposure and response prevention or risperidone in adults with obsessive-compulsive disorder
OBJECTIVE: To compare outcomes after 6-month maintenance treatment of adults diagnosed with obsessive-compulsive disorder (OCD) based on DSM-IV criteria who responded to acute treatment with serotonin reuptake inhibitors (SRIs) augmented by exposure and response prevention (EX/RP) or risperidone. METHOD: A randomized trial was conducted at 2 academic sites from January 2007 through December 2012. In the acute phase, 100 patients on therapeutic SRI dose with at least moderate OCD severity were randomized to 8 weeks of EX/RP, risperidone, or pill placebo. Responders entered the 6-month maintenance phase, continuing the augmentation strategy they received acutely (n = 30 EX/RP, n = 8 risperidone). Independent evaluations were conducted every month. The main outcome was the Yale-Brown Obsessive Compulsive Scale (Y-BOCS). RESULTS: Intent-to-treat analyses indicated that, after 6-month maintenance treatment, EX/RP yielded OCD outcomes that were superior to risperidone (Y-BOCS = 10.95 vs 18.70; t40 = 2.76, P = .009); more patients randomized to EX/RP met response criteria (Y-BOCS decrease \u3e/= 25%: 70% vs 20%; P \u3c .001) and achieved minimal symptoms (Y-BOC
Characteristic extraction in numerical relativity: binary black hole merger waveforms at null infinity
The accurate modeling of gravitational radiation is a key issue for
gravitational wave astronomy. As simulation codes reach higher accuracy,
systematic errors inherent in current numerical relativity wave-extraction
methods become evident, and may lead to a wrong astrophysical interpretation of
the data. In this paper, we give a detailed description of the
Cauchy-characteristic extraction technique applied to binary black hole
inspiral and merger evolutions to obtain gravitational waveforms that are
defined unambiguously, that is, at future null infinity. By this method we
remove finite-radius approximations and the need to extrapolate data from the
near zone. Further, we demonstrate that the method is free of gauge effects and
thus is affected only by numerical error. Various consistency checks reveal
that energy and angular momentum are conserved to high precision and agree very
well with extrapolated data. In addition, we revisit the computation of the
gravitational recoil and find that finite radius extrapolation very well
approximates the result at \scri. However, the (non-convergent) systematic
differences to extrapolated data are of the same order of magnitude as the
(convergent) discretisation error of the Cauchy evolution hence highlighting
the need for correct wave-extraction.Comment: 41 pages, 8 figures, 2 tables, added references, fixed typos. Version
matches published version
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