691 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
Androgenic Effect and Phytochimie of the Bark of Trunk of Buchholzia coriacea Engl. (Capparidaceae)
The testosterone is the main androgen produced by the testes among the males. Her absence is responsible for erectile dysfunction and the loss of the sexual performance. The aim of the present study is to evaluate the androgenic effect and to determine the profile phytochemestry of the barks of trunk of B. coriacea. Fifteen days after the castration, the animals left in group and, received the aqueous extract of B. coriacea (100, 250 and 500 mg/kg, p.o). The sexual parameters (mounts sexual, number of erections, number of ejaculations and the time of latency) have been valued, and compared, to the witnesses groups: water distilled (0,5 ml/100 mg, p.o) and Enanthate of testosterone (1 mg/mL, i.m). The dosage of the testosterone has been achieved by the technic of ELYSA analysis. The determination of the chemical families has been achieved by the technique of coloration in tubes. The aqueous extract of B. coriacea (100,250 and 500 mg/kg, p.o) has an effect androgenic because managed daily during 15 days, it provokes an increase of the rate plasmatic of the testosterone and the bodily weight of the rats, maintains the sexual parameters among the castrated rat, extract the number of ejaculations. The barks of trunk of B. coriacea would contain the stérols, the flavonoides, the saponosids that could be responsible for the sexual effects and androgénic observed. The aqueous extract of the plant would possess the properties androgenic would be to advise the patients presenting problems of masculine barrenness.
Keywords: Androgen - Phytochimie - Buchholzia - coriacea 
Bis[5-oxo-4,5-dihydro-8H-2-azonia-4,8,9-trizabicyclo[4.3.0]nona-2,6,9(1)-triene] sulfate
In the crystal structure of the title compound, 2C5H5N4O+·SO4
2−, N—H⋯O hydrogen bonds assemble the molecules into a two-dimensional network structure parallel to the cb plane. The S atom of the sulfate ion lies on a special position on a twofold axis
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
Fus2 localizes near the site of cell fusion and is required for both cell fusion and nuclear alignment during zygote formation.
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.
Low-abundance HIV species and their impact on mutational profiles in patients with virological failure on once-daily abacavir/lamivudine/zidovudine and tenofovir
Topics in Quantum Computers
I provide an introduction to quantum computers, describing how they might be
realized using language accessible to a solid state physicist. A listing of the
minimal requirements for creating a quantum computer is given. I also discuss
several recent developments in the area of quantum error correction, a subject
of importance not only to quantum computation, but also to some aspects of the
foundations of quantum theory.Comment: 22 pages, Latex, 1 eps figure, Paper to be published in "Mesoscopic
Electron Transport", edited by L. Kowenhoven, G. Schoen and L. Sohn, NATO ASI
Series E, Kluwer Ac. Publ., Dordrecht. v2: typos in refrences fixe
- …