10,631 research outputs found
Unstable particles as open quantum systems
We present the probability preserving description of the decaying particle
within the framework of quantum mechanics of open systems taking into account
the superselection rule prohibiting the superposition of the particle and
vacuum. In our approach the evolution of the system is given by a family of
completely positive trace preserving maps forming one-parameter dynamical
semigroup. We give the Kraus representation for the general evolution of such
systems which allows one to write the evolution for systems with two or more
particles. Moreover, we show that the decay of the particle can be regarded as
a Markov process by finding explicitly the master equation in the Lindblad
form. We also show that there are remarkable restrictions on the possible
strength of decoherence.Comment: 11 pp, 2 figs (published version
Folding in two-dimenensional off-lattice models of proteins
Model off-lattice sequences in two dimensions are constructed so that their
native states are close to an on-lattice target. The Hamiltonian involves the
Lennard-Jones and harmonic interactions. The native states of these sequences
are determined with a high degree of certainty through Monte Carlo processes.
The sequences are characterized thermodynamically and kinetically. It is shown
that the rank-ordering-based scheme of the assignment of contact energies
typically fails in off-lattice models even though it generates high stability
of on-lattice sequences. Similar to the on-lattice case, Go-like modeling, in
which the interaction potentials are restricted to the native contacts in a
target shape, gives rise to good folding properties. Involving other contacts
deteriorates these properties.Comment: REVTeX, 9 pages, 8 EPS figure
Delineation of the Native Basin in Continuum Models of Proteins
We propose two approaches for determining the native basins in off-lattice
models of proteins. The first of them is based on exploring the saddle points
on selected trajectories emerging from the native state. In the second
approach, the basin size can be determined by monitoring random distortions in
the shape of the protein around the native state. Both techniques yield the
similar results. As a byproduct, a simple method to determine the folding
temperature is obtained.Comment: REVTeX, 6 pages, 5 EPS figure
An Assessment of Female Prisoners’ Perception of the Accessibility of Quality Healthcare: A Survey in the Kumasi Central Prisons, Ghana
Background: Accessibility of quality healthcare across the globe has generated a lot of attention among public health practitioners.Aim: This study explored the background characteristics of female prisoners and how it influences their assessment of the quality of accessible healthcare in the Kumasi Female Prison. Subjects and Methods: This descriptive cross-sectional survey was conducted at the Female section of the Kumasi Central Prisons from June to December 2011. We used pretested questionnaires to obtain quantitative data from all 39 inmates of the female Prisons. An in-depth interview was used to obtain qualitative data from the prison healthcare giver. Data were analyzed with Epi Info Version 3.5.1, (Centers for Disease Control and Prevention), Excel, and Graph Pad Prism version 5.00 for Windows (Graph Pad software, San Diego California USA, www.graphpad.com). Results: Using a 12.point scale inventory questionnaire, inmates with no formal education gave the highest mean health provision assessment score (6.0) whereas those with tertiary education gave the lowest (4.5). Females serving prison sentences gave the highest mean health assessment score whereas remand prisoners gave the lowest. Single femalesf mean health assessment score was 5.7 whereas that of married inmates was 4.9. Unemployed inmates scored 5.8, informal 5.4 while civil servants scored 5.0.Conclusion: Access to quality healthcare was poor and demographic characteristics, marital status, educational background, and occupation influenced inmatesf perceptions of accessibility to quality healthcare. Inmates should be encouraged to be proactive in seeking healthcare irrespective of their background characteristics.Keywords: Accessibility, Female, Kumasi, Perception Prisons, Quality of health car
Structure of 55Sc and development of the N=34 subshell closure
The low-lying structure of Sc has been investigated using in-beam
-ray spectroscopy with the Be(Ti,Sc+)
one-proton removal and Be(Sc,Sc+)
inelastic-scattering reactions at the RIKEN Radioactive Isotope Beam Factory.
Transitions with energies of 572(4), 695(5), 1539(10), 1730(20), 1854(27),
2091(19), 2452(26), and 3241(39) keV are reported, and a level scheme has been
constructed using coincidence relationships and -ray
relative intensities. The results are compared to large-scale shell-model
calculations in the - model space, which account for positive-parity
states from proton-hole cross-shell excitations, and to it ab initio
shell-model calculations from the in-medium similarity renormalization group
that includes three-nucleon forces explicitly. The results of proton-removal
reaction theory with the eikonal model approach were adopted to aid
identification of positive-parity states in the level scheme; experimental
counterparts of theoretical and states are
suggested from measured decay patterns. The energy of the first
state, which is sensitive to the neutron shell gap at the Fermi surface, was
determined. The result indicates a rapid weakening of the subshell
closure in -shell nuclei at , even when only a single proton occupies
the orbital
Inverse Orbital Torque via Spin-Orbital Entangled States
While current-induced torque by orbital current has been experimentally found
in various structures, evidence for its reciprocity has been missing so far.
Here, we report experimental evidences of strong inverse orbital torque in
YIG/Pt/CuOx (YIG = Y3Fe5O12) mediated by spin-orbital entangled electronic
states in Pt. By injecting spin current from YIG to Pt by the spin pumping via
ferromagnetic resonance and by the spin Seebeck effect, we find a pronounced
inverse spin Hall effect-like signal. While a part of the signal is explained
as due to the inverse spin-orbital Hall effect in Pt, we also find substantial
increase of the signal in YIG/Pt/CuOx structures compared to the signal in
YIG/Pt. We attribute this to the inverse orbital Edelstein effect at Pt/CuOx
interface mediated by the spin-orbital entangled states in Pt. Our work paves
the way toward understanding of spin-orbital entangled physics in
nonequilibrium and provides a way for electrical detection of the orbital
current in orbitronic device applications.Comment: 8 pages, four figure
microRNA-29b prevents liver fibrosis by attenuating hepatic stellate cell activation and inducing apoptosis through targeting PI3K/AKT pathway
microRNA-29b (miR-29b) is known to be associated with TGF-β-mediated fibrosis, but the mechanistic action of miR-29b in liver fibrosis remains unclear and is warranted for investigation. We found that miR-29b was significantly downregulated in human and mice fibrotic liver tissues and in primary activated HSCs. miR-29b downregulation was directly mediated by Smad3 through binding to the promoter of miR-29b in hepatic stellate cell (HSC) line LX1, whilst miR-29b could in turn suppress Smad3 expression. miR-29b transduction in the liver of mice prevented CCl4 induced-fibrogenesis, concomitant with decreased expression of α-SMA, collagen I and TIMP-1. Ectopic expression of miR-29b in activated HSCs (LX-1, HSC-T6) inhibited cell viability and colony formation, and caused cell cycle arrest in G1 phase by downregulating cyclin D1 and p21cip1. Further, miR-29b induced apoptosis in HSCs mediated by caspase-9 and PARP. miR-29b inhibited its downstream effectors of PIK3R1 and AKT3 through direct targeting their 3'UTR regions. Moreover, knockdown of PIK3R1 or AKT3 suppressed α-SMA and collagen I and induced apoptosis in both HSCs and in mice. In conclusion, miR-29b prevents liver fibrogenesis by inhibiting HSC activation and inducing HSC apoptosis through inhibiting PI3K/AKT pathway. These results provide novel mechanistic insights for the anti-fibrotic effect of miR-29b.published_or_final_versio
Glassy Dynamics of Protein Folding
A coarse grained model of a random polypeptide chain, with only discrete
torsional degrees of freedom and Hookean springs connecting pairs of
hydrophobic residues is shown to display stretched exponential relaxation under
Metropolis dynamics at low temperatures with the exponent , in
agreement with the best experimental results. The time dependent correlation
functions for fluctuations about the native state, computed in the Gaussian
approximation for real proteins, have also been found to have the same
functional form. Our results indicate that the energy landscape exhibits
universal features over a very large range of energies and is relatively
independent of the specific dynamics.Comment: RevTeX, 4 pages, multicolumn, including 5 figures; larger
computations performed, error bars improve
Cost-effectiveness of alternative methods of surgical repair of inguinal hernia
Objectives: To assess the relative cost-effectiveness of laparoscopic methods of inguinal hernia repair compared with open flat mesh and open non-mesh repair. Methods: Data on the effectiveness of these alternatives came from three systematic reviews comparing: (i) laparoscopic methods with open flat mesh or non-mesh methods; (ii) open flat mesh with open non-mesh repair; and (iii) methods that used synthetic mesh to repair the hernia defect with those that did not. Data on costs were obtained from the authors of economic evaluations previously conducted alongside trials included in the reviews. A Markov model was used to model cost-effectiveness for a five-year period after the initial operation. The outcomes of the model were presented using a balance sheet approach and as cost per hernia recurrence avoided and cost per extra day at usual activities. Results: Open flat mesh was the most cost-effective method of preventing recurrences. Laparoscopic repair provided a shorter period of convalescence and less long-term pain compared with open flat mesh but was more costly. The mean incremental cost per additional day back at usual activities compared with open flat mesh was €38 and €80 for totally extraperitoneal and transabdominal preperitoneal repair, respectively. Conclusions: Laparoscopic repair is not cost-effective compared with open flat mesh repair in terms of cost per recurrence avoided. Decisions about the use of laparoscopic repair depend on whether the benefits (reduced pain and earlier return to usual activities) outweigh the extra costs and intraoperative risks. On the evidence presented here, these extra costs are unlikely to be offset by the short-term benefits of laparoscopic repair.Luke Vale, Adrian Grant, Kirsty McCormack, Neil W. Scott and the EU Hernia Trialists Collaboratio
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