843 research outputs found
Quantum rotor description of the Mott-insulator transition in the Bose-Hubbard model
We present the novel approach to the Bose-Hubbard model using the
quantum rotor description. The effective action formalism
allows us to formulate a problem in the phase only action and obtain an
analytical formulas for the critical lines. We show that the nontrivial
phase field configurations have an impact on the phase
diagrams. The topological character of the quantum field is governed by terms
of the integer charges - winding numbers. The comparison presented results to
recently obtained quantum Monte Carlo numerical calculations suggests that the
competition between quantum effects in strongly interacting boson systems is
correctly captured by our model.Comment: accepted to PR
Preventing Pneumonia Through Early Mobilization of Critically Ill Adults
The purpose of this critically appraised topic (CAT) is to investigate early mobilization and its effect on preventing pneumonia in adults in the intensive care unit (ICU). The final portfolio contains four research articles from both national and international journals. Study designs included two meta-analyses, one case series, and one retrospective study. All four of the articles specifically described the effects of early mobilization on individuals in the hospital and ICU and showed positive results in reducing the likelihood of developing pneumonia. This CAT will be used to draft new practice guidelines for mentoring new managers in both occupational therapy and physical therapy
Interference effects in isolated Josephson junction arrays with geometric symmetries
As the size of a Josephson junction is reduced, charging effects become
important and the superconducting phase across the link turns into a periodic
quantum variable. Isolated Josephson junction arrays are described in terms of
such periodic quantum variables and thus exhibit pronounced quantum
interference effects arising from paths with different winding numbers
(Aharonov-Casher effects). These interference effects have strong implications
for the excitation spectrum of the array which are relevant in applications of
superconducting junction arrays for quantum computing. The interference effects
are most pronounced in arrays composed of identical junctions and possessing
geometric symmetries; they may be controlled by either external gate potentials
or by adding/removing charge to/from the array. Here we consider a loop of N
identical junctions encircling one half superconducting quantum of magnetic
flux. In this system, the ground state is found to be non-degenerate if the
total number of Cooper pairs on the array is divisible by N, and doubly
degenerate otherwise (after the stray charges are compensated by the gate
voltages).Comment: 9 pages, 6 figure
LEVERAGING PLASMA-DERIVED EXOSOMES FOR BIOMARKER DISCOVERY IN SICKLE CELL DISEASE: PREPARATION FOR A LARGE PROSPECTIVE STUDY
Diverse clinical variability among sickle cell disease (SCD) patients opposes crises prediction, health monitor- ing and streamlined management. Thus, an unmet need for objective biomarkers prevails. Exosomes are extra-cellular nano-vesicles (50-150nm), enriched in bioactive lipids, proteins, mRNAs and miRNAs, released by cells. They transport molecular cargo to nearby/distant cells to affect-regulate biological processes. Recent studies by Khalyfa et al. assessed the plasma exosome content, their sources and transcriptomics signature as predictive marker in SCD children with acute chest syndrome. However, the small sample sizes (32 and 33 individuals, respectively) may not capture the clinical variability
Possible realization of Josephson charge qubits in two coupled Bose-Einstein condensates
We demonstrate that two coupled Bose-Einstein condensates (BEC) at zero
temperature can be used to realize a qubit which is the counterpart of
Josephson charge qubits. The two BEC are weakly coupled and confined in an
asymmetric double-well trap. When the "charging energy" of the system is much
larger than the Josephson energy and the system is biased near a degeneracy
point, the two BEC represent a qubit with two states differing only by one
atom. The realization of the BEC qubits in realistic BEC experiments is briefly
discussed.Comment: 4 pages; comments are welcome / Corrected typos in Eq. (16); a note
adde
nu=1/2 quantum Hall effect in the Aharonov-Casher geometry in a mesoscopic ring
We study the effect of an electric charge in the middle of a ring of
electrons in a magnetic field such as . In the absence of the
central charge, a residual current should appear due to an Aharanov-Bohm
effect. As the charge varies, periodic currents should appear in the ring. We
evaluate the amplitude of these currents, as well as their period as the
central charge varies. The presence of these currents should be a direct
signature of the existence of a statistical gauge field in the
quantum Hall effect. Numerical diagonalizations for a small number of electrons
on the sphere are also carried out. The numerical results up to 9 electrons are
qualitatively consistent with the mean field picture.Comment: 23 pages,14 included postscript figures, submitted to Phys. Rev.
Comparative gender analysis of the efficacy and safety of atazanavir/ritonavir and lopinavir/ritonavir at 96 weeks in the CASTLE study.
OBJECTIVES: To examine whether the overall results of the CASTLE study pertain to both genders, we analysed the efficacy and safety of atazanavir/ritonavir and lopinavir/ritonavir in 277 female and 606 male patients in the open-label, multinational trial over 96 weeks. The trial is registered with ClinicalTrials.gov, number NCT00272779.
METHODS: Treatment-naive patients aged ≥ 18 years with HIV-1 RNA ≥ 5000 copies/mL were randomized to receive either atazanavir/ritonavir 300/100 mg once daily or lopinavir/ritonavir 400/100 mg twice daily, with fixed-dose tenofovir/emtricitabine 300/200 mg once daily.
RESULTS: At week 96, confirmed virological response rates (HIV RNA \u3c50 copies\u3e/mL; intent-to-treat analysis) were higher in women and men receiving atazanavir/ritonavir than those receiving lopinavir/ritonavir and lower in women than men in both treatment arms (67% of women and 77% of men on atazanavir/ritonavir and 63% of women and 71% of men on lopinavir/ritonavir). These differences were not observed in the on-treatment analysis. Mean change in CD4 cell count from baseline to week 96 was 265 cells/mm(3) for women and 269 cells/mm(3) for men on atazanavir/ritonavir and 298 cells/mm(3) for women and 286 cells/mm(3) for men on lopinavir/ritonavir. Discontinuation rates were higher in women than men in each treatment arm (22% of women and 15% of men on atazanavir/ritonavir and 29% of women and 18% of men on lopinavir/ritonavir). In women and men, grade 2-4 nausea and diarrhoea were more frequent in the lopinavir/ritonavir group; jaundice and hyperbilirubinaemia occurred more frequently in the atazanavir/ritonavir group.
CONCLUSIONS: Once-daily atazanavir/ritonavir is an effective and well-tolerated therapeutic option for women and men with HIV-1 infection. The sex-based differences in response may be due to higher discontinuation rates in women
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