16,433 research outputs found
Long-distance entanglement and quantum teleportation in coupled cavity arrays
We introduce quantum spin models whose ground states allow for sizeable
entanglement between distant spins. We discuss how spin models with global
end-to-end entanglement realize quantum teleportation channels with optimal
compromise between scalability and resilience to thermal decoherence, and can
be implemented straightforwardly in suitably engineered arrays of coupled
optical cavities.Comment: 4 pages, 5 figures. To appear in Phys. Rev. A (Rapid Communication
Enhancement of cooperation in highly clustered scale-free networks
We study the effect of clustering on the organization of cooperation, by
analyzing the evolutionary dynamics of the Prisoner's Dilemma on scale-free
networks with a tunable value of clustering. We find that a high value of the
clustering coefficient produces an overall enhancement of cooperation in the
network, even for a very high temptation to defect. On the other hand, high
clustering homogeneizes the process of invasion of degree classes by defectors,
decreasing the chances of survival of low densities of cooperator strategists
in the network.Comment: 4 pages, 3 figure
Geometric characterization of separability and entanglement in pure Gaussian states by single-mode unitary operations
We present a geometric approach to the characterization of separability and
entanglement in pure Gaussian states of an arbitrary number of modes. The
analysis is performed adapting to continuous variables a formalism based on
single subsystem unitary transformations that has been recently introduced to
characterize separability and entanglement in pure states of qubits and qutrits
[arXiv:0706.1561]. In analogy with the finite-dimensional case, we demonstrate
that the bipartite entanglement of a multimode pure Gaussian state
can be quantified by the minimum squared Euclidean distance between the state
itself and the set of states obtained by transforming it via suitable local
symplectic (unitary) operations. This minimum distance, corresponding to a,
uniquely determined, extremal local operation, defines a novel entanglement
monotone equivalent to the entropy of entanglement, and amenable to direct
experimental measurement with linear optical schemes.Comment: 7 pages, 1 figure. Discussion expanded, to appear in PR
Health in my community: Conducting and evaluating photovoice as a tool to promote environmental health and leadership among Latino/a youth
BackgroundThe PhotoVoice method has shown substantial promise for work with youth in metropolitan areas, yet its potential for use with Latino youth from agricultural areas has not been well documented.ObjectivesThis project was designed to teach environmental health to 15 high school youth while building their individual and community capacity for studying and addressing shared environmental concerns. The project also aimed to test the utility of PhotoVoice with Latino agricultural youth.MethodsFifteen members of the Youth Community Council (YCC), part of a 15-year project with farmworker families in Salinas, CA, took part in a 12-week PhotoVoice project. Their pictures captured the assets and strengths of their community related to environmental health, and were then analyzed by participants. A multi-pronged evaluation was conducted.ResultsYCC members identified concerns such as poor access to affordable, healthy foods and lack of safe physical spaces in which to play, as well as assets, including caring adults and organizations, and open spaces in surrounding areas. Participants presented their findings on radio, television, at local community events, and to key policy makers. The youth also developed two action plans, a successful 5K run/walk and a school recycling project, still in progress. Evaluation results included significant changes in such areas as perceived ability to make presentations, leadership, and self-confidence, as well as challenges including transportation, group dynamics, and gaining access to people in power.ConclusionThe PhotoVoice method shows promise for environmental health education and youth development in farmworker communities
GC-MS-based metabolomics study of single-and dual-species biofilms of Candida albicans and Klebsiella pneumoniae
Candida albicans and Klebsiella pneumoniae frequently co-exist within the human host as a complex biofilm community. These pathogens are of interest because their association is also related to significantly increased morbidity and mortality in hospitalized patients. With the aim of highlighting metabolic shifts occurring in the dual-species biofilm, an untargeted GC-MS-based metabolomics approach was applied to single and mixed biofilms of C. albicans and K. pneumoniae. Metabolomic results showed that among the extracellular metabolites identified, approximately 40 compounds had significantly changed relative abundance, mainly involving central carbon, amino acid, vitamin, and secondary metabolisms, such as serine, leucine, arabitol, phosphate, vitamin B6, cyclo-(Phe-Pro), trehalose, and nicotinic acid. The results were related to the strict interactions between the two species and the different microbial composition in the early and mature biofilms
A paraoxonase gene polymorphism, PON 1 (55), as an independent risk factor for increased carotid intima-media tickness in middle-aged women.
Acoustic analogues of black hole singularities
We search for acoustic analogues of a spherical symmetric black hole with a
pointlike source. We show that the gravitational system has a dynamical
counterpart in the constrained, steady motion of a fluid with a planar source.
The equations governing the dynamics of the gravitational system can be exactly
mapped in those governing the motion of the fluid. The different meaning that
singularities and sources have in fluid dynamics and in general relativity is
also discussed. Whereas in the latter a pointlike source is always associated
with a (curvature) singularity in the former the presence of sources does not
necessarily imply divergences of the fields.Comment: 9 pages, no figure
Reply Comment on "Entropy of 2D black holes from counting microstates"
We show that the arguments proposed by Park and Yee against our recent
derivation of the statistical entropy of 2D black holes do not apply to the
case under considerationComment: 3 pages, LaTex file, reply to comment hep-th/991021
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