1,206 research outputs found
Curbing the HIV Epidemic by Supporting Effective Engagement in HIV Care: Recommendations for Health Plans and Health Care Purchasers
The United States is poised to dramatically reduce the scope of its HIV epidemic, but this demands increased leadership and attention from health plans and health care purchasers (including Medicaid, Medicare, marketplaces, and other private purchasers). This new amfAR report identifies changes in policy and practice in clinics, communities, and health care programs to reduce unnecessary health spending, increase the effectiveness of services, and increase the integration of services. Done right, the same steps that lead to appropriate management of care by health plans and purchasers also will help to achieve national public health goals
Algebraic Bethe Ansatz for a discrete-state BCS pairing model
We show in detail how Richardson's exact solution of a discrete-state BCS
(DBCS) model can be recovered as a special case of an algebraic Bethe Ansatz
solution of the inhomogeneous XXX vertex model with twisted boundary
conditions: by implementing the twist using Sklyanin's K-matrix construction
and taking the quasiclassical limit, one obtains a complete set of conserved
quantities, H_i, from which the DBCS Hamiltonian can be constructed as a second
order polynomial. The eigenvalues and eigenstates of the H_i (which reduce to
the Gaudin Hamiltonians in the limit of infinitely strong coupling) are exactly
known in terms of a set of parameters determined by a set of on-shell Bethe
Ansatz equations, which reproduce Richardson's equations for these parameters.
We thus clarify that the integrability of the DBCS model is a special case of
the integrability of the twisted inhomogeneous XXX vertex model. Furthermore,
by considering the twisted inhomogeneous XXZ model and/or choosing a generic
polynomial of the H_i as Hamiltonian, more general exactly solvable models can
be constructed. -- To make the paper accessible to readers that are not Bethe
Ansatz experts, the introductory sections include a self-contained review of
those of its feature which are needed here.Comment: 17 pages, 5 figures, submitted to Phys. Rev.
Dynamics of Global Entanglement under Decoherence
We investigate the dynamics of global entanglement, the Meyer-Wallach
measure, under decoherence, analytically. We study two important class of
multi-partite entangled states, the Greenberger-Horne-Zeilinger and the W
state. We obtain exact results for various models of system-environment
interactions (decoherence). Our results shows distinctly different scaling
behavior for these initially entangled states indicating a relative robustness
of the W state, consistent with previous studies.Comment: 5 pages and 5 figure
Foundations of Quantum Discord
This paper summarizes the basics of the notion of quantum discord and how it
relates to other types of correlations in quantum physics. We take the
fundamental information theoretic approach and illustrate our exposition with a
number of simple examples.Comment: 3 pages, special issue edited by Diogo de Oliveira Soares Pinto et a
Experiences with HPTN 067/ADAPT Study-Provided Open-Label PrEP Among Women in Cape Town: Facilitators and Barriers Within a Mutuality Framework.
Placebo-controlled trials of pre-exposure prophylaxis (PrEP) have reported challenges with study-product uptake and use, with the greatest challenges reported in studies with young women in sub-Saharan Africa. We conducted a qualitative sub-study to explore experiences with open-label PrEP among young women in Cape Town, South Africa participating in HTPN 067/Alternative Dosing to Augment Pre-Exposure Prophylaxis Pill Taking (ADAPT). HPTN 067/ADAPT provided open label oral FTC/TDF PrEP to young women in Cape Town, South Africa who were randomized to daily and non-daily PrEP regimens. Following completion of study participation, women were invited into a qualitative sub-study including focus groups and in-depth interviews. Interviews and groups followed a semi-structured guide, were recorded, transcribed, and translated to English from isiXhosa, and coded using framework analysis. Sixty of the 179 women enrolled in HPTN 067/ADAPT participated in either a focus group (six groups for a total of 42 participants) or an in-depth interview (n = 18). This sample of mostly young, unmarried women identified facilitators of and barriers to PrEP use, as well as factors influencing study participation. Cross-cutting themes characterizing discourse suggested that women placed high value on contributing to the well-being of one's community (Ubuntu), experienced a degree of skepticism towards PrEP and the study more generally, and reported a wide range of approaches towards PrEP (ranging from active avoidance to high levels of persistence and adherence). A Mutuality Framework is proposed that identifies four dynamics (distrust, uncertainty, alignment, and mutuality) that represent distinct interactions between self, community and study and serve to contextualize women's experiences. Implications for better understanding PrEP use, and non-use, and intervention opportunities are discussed. In this sample of women, PrEP use in the context of an open-label research trial was heavily influenced by underlying beliefs about safety, reciprocity of contributions to community, and trust in transparency and integrity of the research. Greater attention to factors positioning women in the different dynamics of the proposed Mutuality Framework could direct intervention approaches in clinical trials, as well as open-label PrEP scale-up
Out of equilibrium correlation functions of quantum anisotropic XY models: one-particle excitations
We calculate exactly matrix elements between states that are not eigenstates
of the quantum XY model for general anisotropy. Such quantities therefore
describe non equilibrium properties of the system; the Hamiltonian does not
contain any time dependence. These matrix elements are expressed as a sum of
Pfaffians. For single particle excitations on the ground state the Pfaffians in
the sum simplify to determinants.Comment: 11 pages, no figures; revtex. Minor changes in the text; list of
refs. modifie
Integrable spin-boson interaction in the Tavis-Cummings model from a generic boundary twist
We construct models describing interaction between a spin and a single
bosonic mode using a quantum inverse scattering procedure. The boundary
conditions are generically twisted by generic matrices with both diagonal and
off-diagonal entries. The exact solution is obtained by mapping the transfer
matrix of the spin-boson system to an auxiliary problem of a spin- coupled
to the spin- with general twist of the boundary condition. The corresponding
auxiliary transfer matrix is diagonalized by a variation of the method of
-matrices of Baxter. The exact solution of our problem is obtained applying
certain large- limit to , transforming it into the bosonic algebra.Comment: 6 pages, revtex; 1 figure. To be published in EPJ
Fluctuations of Quantum Entanglement
It is emphasized that quantum entanglement determined in terms of the von
Neumann entropy operator is a stochastic quantity and, therefore, can
fluctuate. The rms fluctuations of the entanglement entropy of two-qubit
systems in both pure and mixed states have been obtained. It has been found
that entanglement fluctuations in the maximally entangled states are absent.
Regions where the entanglement fluctuations are larger than the entanglement
itself (strong fluctuation regions) have been revealed. It has been found that
the magnitude of the relative entanglement fluctuations is divergent at the
points of the transition of systems from an entangled state to a separable
state. It has been shown that entanglement fluctuations vanish in the separable
states.Comment: 5 pages, 4 figure
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