1,043 research outputs found
The Effective Particle-Hole Interaction and the Optical Response of Simple Metal Clusters
Following Sham and Rice [L. J. Sham, T. M. Rice, Phys. Rev. 144 (1966) 708]
the correlated motion of particle-hole pairs is studied, starting from the
general two-particle Greens function. In this way we derive a matrix equation
for eigenvalues and wave functions, respectively, of the general type of
collective excitation of a N-particle system. The interplay between excitons
and plasmons is fully described by this new set of equations. As a by-product
we obtain - at least a-posteriori - a justification for the use of the TDLDA
for simple-metal clusters.Comment: RevTeX, 15 pages, 5 figures in uufiles format, 1 figure avaible from
[email protected]
Effective Field Theory and Finite Density Systems
This review gives an overview of effective field theory (EFT) as applied at
finite density, with a focus on nuclear many-body systems. Uniform systems with
short-range interactions illustrate the ingredients and virtues of many-body
EFT and then the varied frontiers of EFT for finite nuclei and nuclear matter
are surveyed.Comment: 27 pages, 5 figure
Kinetic Roughening in Surfaces of Crystals Growing on Disordered Substrates
Substrate disorder effects on the scaling properties of growing crystalline
surfaces in solidification or epitaxial deposition processes are investigated.
Within the harmonic approach there is a phase transition into a low-temperature
(low-noise) superrough phase with a continuously varying dynamic exponent z>2
and a non-linear response. In the presence of the KPZ nonlinearity the disorder
causes the lattice efects to decay on large scales with an intermediate
crossover behavior. The mobility of the rough surface hes a complex dependence
on the temperature and the other physical parameters.Comment: 13 pages, 2 figures (not included). Submitted to Phys. Rev. Letts.
Use Latex twic
Orthogonal methods based ant colony search for solving continuous optimization problems
Research into ant colony algorithms for solving continuous optimization problems forms one of the most
significant and promising areas in swarm computation. Although traditional ant algorithms are designed for combinatorial
optimization, they have shown great potential in solving a wide range of optimization problems, including continuous
optimization. Aimed at solving continuous problems effectively, this paper develops a novel ant algorithm termed "continuous orthogonal ant colony" (COAC), whose pheromone deposit mechanisms would enable ants to search for
solutions collaboratively and effectively. By using the orthogonal design method, ants in the feasible domain can explore
their chosen regions rapidly and e±ciently. By implementing an "adaptive regional radius" method, the proposed
algorithm can reduce the probability of being trapped in local optima and therefore enhance the global search capability and accuracy. An elitist strategy is also employed to reserve the most valuable points. The performance of the COAC is
compared with two other ant algorithms for continuous optimization of API and CACO by testing seventeen functions
in the continuous domain. The results demonstrate that the proposed COAC algorithm outperforms the others
The hypertension cascade of care in the midst of conflict: the case of the Gaza Strip
Although hypertension constitutes a substantial burden in conflict-affected areas, little is known about its prevalence, control, and management in Gaza. This study aims to estimate the prevalence and correlates of hypertension, its diagnosis and control among adults in Gaza. We conducted a representative, cross-sectional, anonymous, household survey of 4576 persons older than 40 years in Gaza in mid-2020. Data were collected through face-to-face interviews, anthropometric, and blood pressure measurements. Hypertension was defined in anyone with an average systolic blood pressure ≥140 mmHg or average diastolic blood pressure ≥90 mmHg from two consecutive readings or a hypertension diagnosis. The mean age of participants was 56.9 ± 10.5 years, 54.0% were female and 68.5% were Palestinian refugees. The prevalence of hypertension was 56.5%, of whom 71.5% had been diagnosed. Hypertension was significantly higher among older participants, refugees, ex-smokers, those who were overweight or obese, and had other co-morbidities including mental illnesses. Two-thirds (68.3%) of those with hypertension were on treatment with one in three (35.6%) having their hypertension controlled. Having controlled hypertension was significantly higher in females, those receiving all medications for high blood pressure and those who never or rarely added salt to food. Investing in comprehensive but cost-effective initiatives that strengthen the prevention, early detection and timely treatment of hypertension in conflict settings is critical. It is essential to better understand the underlying barriers behind the lack of control and develop multi-sectoral programs to address these barriers
Kinks in the Kondo problem
We find the exact quasiparticle spectrum for the continuum Kondo problem of
species of electrons coupled to an impurity of spin . In this
description, the impurity becomes an immobile quasiparticle sitting on the
boundary. The particles are ``kinks'', which can be thought of as field
configurations interpolating between adjacent wells of a potential with
degenerate minima. For the overscreened case , the boundary has this kink
structure as well, which explains the non-integer number of boundary states
previously observed. Using simple arguments along with the consistency
requirements of an integrable theory, we find the exact elastic -matrix for
the quasiparticles scattering among themselves and off of the boundary. This
allows the calculation of the exact free energy, which agrees with the known
Bethe ansatz solution.Comment: 9 pages +1 figur
Overrepresentation of IL-17A and IL-22 Producing CD8 T Cells in Lesional Skin Suggests Their Involvement in the Pathogenesis of Psoriasis
Background: Although recent studies indicate a crucial role for IL-17A and IL-22 producing T cells in the pathogenesis of psoriasis, limited information is available on their frequency and heterogeneity and their distribution in skin in situ. Methodology/Principal Findings: By spectral imaging analysis of double-stained skin sections we demonstrated that IL-17 was mainly expressed by mast cells and neutrophils and IL-22 by macrophages and dendritic cells. Only an occasional IL-17(pos), but no IL-22(pos) T cell could be detected in psoriatic skin, whereas neither of these cytokines was expressed by T cells in normal skin. However, examination of in vitro-activated T cells by flow cytometry revealed that substantial percentages of skin-derived CD4 and CD8 T cells were able to produce IL-17A alone or together with IL-22 (i.e. Th17 and Tc17, respectively) or to produce IL-22 in absence of IL-17A and IFN-gamma (i.e. Th22 and Tc22, respectively). Remarkably, a significant proportional rise in Tc17 and Tc22 cells, but not in Th17 and Th22 cells, was found in T cells isolated from psoriatic versus normal skin. Interestingly, we found IL-22 single-producers in many skin-derived IL-17A(pos) CD4 and CD8 T cell clones, suggesting that in vivo IL-22 single-producers may arise from IL-17A(pos) T cells as well. Conclusions/Significance: The increased presence of Tc17 and Tc22 cells in lesional psoriatic skin suggests that these types of CD8 T cells play a significant role in the pathogenesis of psoriasis. As part of the skin-derived IL-17A(pos) CD4 and CD8 T clones developed into IL-22 single-producers, this demonstrates plasticity in their cytokine production profile and suggests a developmental relationship between Th17 and Th22 cells and between Tc17 and Tc22 cell
Unique Cardiac Purkinje Fiber Transient-Outward Current Beta-Subunit Composition: A Potential Molecular Link to Idiopathic Ventricular Fibrillation.
Rationale: A chromosomal-haplotype producing cardiac overexpression of dipeptidyl peptidase-like protein-6 (DPP6) causes familial idiopathic ventricular fibrillation (IVF). The molecular basis of transient-outward current (Ito) in Purkinje fibers (PFs) is poorly understood. We hypothesized that DPP6 contributes to PF Ito and that its overexpression might specifically alter PF Ito-properties and repolarization. Objective: To assess the potential role of DPP6 in PF-Ito. Methods and Results: Clinical data in 5 IVF-patients suggested arrhythmia-origin in the PF conducting-system. PF and ventricular-muscle (VM) Ito had similar density, but PF Ito differed from VM in having tetraethylammonium-sensitivity and slower recovery. DPP6-overexpression significantly increased, whereas DPP6-kockdown reduced, Ito-density and tetraethylammonium-sensitivity in canine PF, but not VM-cells. The K+-channel interacting beta-subunit KChIP2, essential for normal expression of transient outward current (Ito) in VM, was weakly-expressed in human PFs, whereas DPP6 and frequenin (NCS-1) were enriched. Heterologous expression of Kv4.3 in Chinese hamster ovary (CHO)-cells produced very small Ito; Ito-amplitude was greatly enhanced by co-expression with KChIP2 or DPP6. Co expression of DPP6 with Kv4.3 and KChIP2 failed to alter Ito versus Kv4.3/KChIP2 alone, but DPP6 expression with Kv4.3 and NCS-1 (to mimic PF Ito-composition), greatly enhanced Ito versus Kv4.3/NCS-1 and recapitulated characteristic PF kinetic/pharmacological properties. A mathematical model of cardiac PF action potentials showed that Ito-enhancement can greatly accelerate PF repolarization. Conclusions: These results point to a previously-unknown central role of DPP6 in PF Ito, with DPP6 gain-of-function selectively enhancing PF-current, and suggest that a DPP6-mediated PF early repolarization syndrome might be a novel molecular paradigm for some forms of IVF
The rapidly pulsating sdO star, SDSS J160043.6+074802.9
A spectroscopic analysis of SDSS J160043.6+074802.9, a binary system
containing a pulsating subdwarf-O (sdO) star with a late-type companion, yields
Teff = 70 000 +/- 5000 K and log g = 5.25 +/- 0.30, together with a most likely
type of K3V for the secondary star. We compare our results with atmospheric
parameters derived by Fontaine et al. (2008) and in the context of existing
evolution models for sdO stars. New and more extensive photometry is also
presented which recovers most, but not all, frequencies found in an earlier
paper. It therefore seems probable that some pulsation modes have variable
amplitudes. A non-adiabatic pulsation analysis of uniform metallicity sdO
models show those having log g > 5.3 to be more likely to be unstable and
capable of driving pulsation in the observed frequency range.Comment: 14 pages, 12 figures, accepted for publication in MNRAS, 2009
September
Effects of early intracoronary streptokinase on infarct size estimated from cumulative enzyme release and on enzyme release rate: A randomized trial of 533 patients with acute myocardial infarction
The effects of early intracoronary streptokinase (SK) on enzymatic infarct size and rate of enzyme release were studied in a randomized multicenter trial. A total of 533 patients with acute myocardial infarction (AMI) were allocated to either the SK treatment group (n = 269) or the conventional (control) treatment group (n = 264). Enzymatic infarct size was represented by the cumulative quantity of alpha-hydroxybutyrate dehydrogenase (HBDH) released by the heart per liter of plasma in the first 72 hours. Rate of enzyme release was represented by the ratio of HBDH quantities released in 24 hours and 72 hours. On an "intention to treat" basis, the SK group had a smaller (by 30%; p = 0.0001) median enzymatic infarct size and a higher (by 35%; p = 0.0001) median rate of enzyme release than the control group. Limitation of infarct size was less apparent in patients tre
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