3,896 research outputs found
Recommended from our members
Depression predicts revascularization procedures for 5 years after coronary angiography.
OBJECTIVE:Depression has been reported to increase cardiac event rates and functional impairment in patients with coronary disease. This article describes the impact of depression on subsequent healthcare utilization for such patients. METHODS:One hundred ninety-eight health maintenance organization patients with stable coronary disease were interviewed after elective angiography using a structured psychiatric diagnostic scale. Cardiac events, hospitalizations, procedures, and costs were monitored for the next 5 years through automated data. Subjects were classified at the time of angiography by modified DSM-IV criteria into those with major, minor, and no depression. RESULTS:In univariate analyses, the no depression group (N = 136) was most likely to receive coronary artery bypass grafting (CABG) (61% vs. 36% in the major depression group vs. 27% in the minor depression group, p =.001), and the major depression group (N = 25) was most likely to receive percutaneous transluminal coronary angioplasty (PTCA) (44% vs. 14% in the minor depression group vs. 24% in the no depression group). The minor depression group (N = 37) was least likely to be hospitalized for cardiac reasons during follow-up (54% vs. 80% in the major depression group vs. 80% in the no depression group, p =.005). Five-year rates of myocardial infarction and death did not differ significantly between groups. Proportional hazard models showed that those in the depression groups differed in time from catheterization to CABG (chi2(2) = 11.9, p =.003) and time to PCTA (chi2(2) = 7.74, p =.02) after controlling for relevant covariates. Median regression showed that patients with no depression had higher costs during the first year but tended to have lower costs in years 2 through 5 than patients with minor or major depression. CONCLUSIONS:Depression status at angiography is associated with the need for revascularization and total healthcare costs for the following year
Coexisting Kondo singlet state with antiferromagnetic long-range order: A possible ground state for Kondo insulators
The ground-state phase diagram of a half-filled anisotropic Kondo lattice
model is calculated within a mean-field theory. For small transverse exchange
coupling , the ground state shows an antiferromagnetic
long-range order with finite staggered magnetizations of both localized spins
and conduction electrons. When , the long-range order
is destroyed and the system is in a disordered Kondo singlet state with a
hybridization gap. Both ground states can describe the low-temperature phases
of Kondo insulating compounds. Between these two distinct phases, there may be
a coexistent regime as a result of the balance between local Kondo screening
and magnetic interactions.Comment: four pages, Revtex, one figure; to be published in Phys. Rev. B, 1
July issue, 200
Configuration Mixing within the Energy Density Functional Formalism: Removing Spurious Contributions from Non-Diagonal Energy Kernels
Multi-reference calculations along the lines of the Generator Coordinate
Method or the restoration of broken symmetries within the nuclear Energy
Density Functional (EDF) framework are becoming a standard tool in nuclear
structure physics. These calculations rely on the extension of a
single-reference energy functional, of the Gogny or the Skyrme types, to
non-diagonal energy kernels. There is no rigorous constructive framework for
this extension so far. The commonly accepted way proceeds by formal analogy
with the expressions obtained when applying the generalized Wick theorem to the
non-diagonal matrix element of a Hamilton operator between two product states.
It is pointed out that this procedure is ill-defined when extended to EDF
calculations as the generalized Wick theorem is taken outside of its range of
applicability. In particular, such a procedure is responsible for the
appearance of spurious divergences and steps in multi-reference EDF energies,
as was recently observed in calculations restoring particle number or angular
momentum. In the present work, we give a formal analysis of the origin of this
problem for calculations with and without pairing, i.e. constructing the
density matrices from either Slater determinants or quasi-particle vacua. We
propose a correction to energy kernels that removes the divergences and steps,
and which is applicable to calculations based on any symmetry restoration or
generator coordinate. The method is formally illustrated for particle number
restoration and is specified to configuration mixing calculations based on
Slater determinants.Comment: 27 pages, 1 figure, accepted for publication in PR
Fine structure of the isoscalar giant quadrupole resonance in 40Ca due to Landau damping?
The fragmentation of the Isoscalar Giant Quadrupole Resonance (ISGQR) in 40Ca
has been investigated in high energy-resolution experiments using proton
inelastic scattering at E_p = 200 MeV. Fine structure is observed in the region
of the ISGQR and its characteristic energy scales are extracted from the
experimental data by means of a wavelet analysis. The experimental scales are
well described by Random Phase Approximation (RPA) and second-RPA calculations
with an effective interaction derived from a realistic nucleon-nucleon
interaction by the Unitary Correlation Operator Method (UCOM). In these results
characteristic scales are already present at the mean-field level pointing to
their origination in Landau damping, in contrast to the findings in heavier
nuclei and also to SRPA calculations for 40Ca based on phenomenological
effective interactions, where fine structure is explained by the coupling to
two-particle two-hole (2p-2h) states.Comment: Phys. Lett. B, in pres
BBMS + + – basic bioinformatics meta-searcher
In this paper we present a Basic Bioinformatics Meta-searcher (BBMS), a web-based service aiming to simplify and integrate biological data searching through selected biological databases. BBMS facilitates biological data searching enabling multiple sources transparently, increasing research productivity as it avoids time consuming learning and parameterization of different search engines. As a complementary service, BBMS provides insight and links to common online bioinformatics tools. Users’ feedback when evaluating BBMS in terms of usability, usefulness and efficiency was very positive
Patient level pooled analysis of 68,500 patients from seven major vitamin D fracture trials in the US and Europe
Objectives To identify participants’ characteristics that influence the anti-fracture efficacy of vitamin D or vitamin
D plus calcium with respect to any fracture, hip fracture, and clinical vertebral fracture and to assess the influence of dosing regimens and co-administration of calcium. Design Individual patient data analysis using pooled data from randomised trials. Data sources Seven major randomised trials of vitamin D with calcium or vitamin D alone, yielding a total of 68 517 participants (mean age 69.9 years, range 47-107 years, 14.7% men). Study selection Studies included were randomised studies with at least one intervention arm in which vitamin D was given, fracture as an outcome, and at least 1000 participants. Data synthesis Logistic regression analysis was used to identify significant interaction terms, followed by Cox’s proportional hazards models incorporating age, sex, fracture history, and hormone therapy and bisphosphonate use. Results Trials using vitamin D with calcium showed a
reduced overall risk of fracture (hazard ratio 0.92, 95% confidence interval 0.86 to 0.99, P=0.025) and hip fracture (all studies: 0.84, 0.70 to 1.01, P=0.07; studies using 10 μg of vitamin D given with calcium: 0.74, 0.60 to 0.91, P=0.005). For vitamin D alone in daily doses of 10 μg or 20 μg, no significant effects were found. No interaction was found between fracture history and treatment
response, nor any interaction with age, sex, or hormone replacement therapy. Conclusion This individual patient data analysis indicates that vitamin D given alone in doses of 10-20 μg is not effective in preventing fractures. By contrast, calcium and vitamin D given together reduce hip fractures and total fractures, and probably vertebral fractures, irrespective of age, sex, or previous fractures.The WHI program is funded by the National Heart, Lung, and Blood Institute, National Institutes of Health, US Department of Health and Human Services through contracts N01WH22110, 24152, 32100-2, 32105-6, 32108-9, 32111-13, 32115, 32118-32119, 32122, 42107-26, 42129-32, and 44221. AA acknowledges personal funding from the UK Medical Research Council and Chief Scientist Office of the Scottish Government Health Directorates
Limit laws of entrance times for low complexity Cantor minimal systems
This paper is devoted to the study of limit laws of entrance times to
cylinder sets for Cantor minimal systems of zero entropy using their
representation by means of ordered Bratteli diagrams. We study in detail
substitution subshifts and we prove these limit laws are piecewise linear
functions. The same kind of results is obtained for classical low complexity
systems given by non stationary ordered Bratteli diagrams
Theory of proximity effect in superconductor/ferromagnet heterostructures
We present a microscopic theory of proximity effect in the
ferromagnet/superconductor/ferromagnet (F/S/F) nanostructures where S is s-wave
low-T_c superconductor and F's are layers of 3d transition ferromagnetic metal.
Our approach is based on the solution of Gor'kov equations for the normal and
anomalous Green's functions together with a self-consistent evaluation of the
superconducting order parameter. We take into account the elastic
spin-conserving scattering of the electrons assuming s-wave scattering in the S
layer and s-d scattering in the F layers. In accordance with the previous
quasiclassical theories, we found that due to exchange field in the ferromagnet
the anomalous Green's function F(z) exhibits the damping oscillations in the
F-layer as a function of distance z from the S/F interface. In the given model
a half of period of oscillations is determined by the length \xi_m^0 = \pi
v_F/E_ex, where v_F is the Fermi velocity and E_ex is the exchange field, while
damping is governed by the length l_0 = (1/l_{\uparrow} +
1/l_{\downarrow})^{-1} with l_{\uparrow} and l_{\downarrow} being
spin-dependent mean free paths in the ferromagnet. The superconducting
transition temperature T_c(d_F) of the F/S/F trilayer shows the damping
oscillations as a function of the F-layer thickness d_F with period \xi_F =
\pi/\sqrt{m E_ex}, where m is the effective electron mass. We show that strong
spin-conserving scattering either in the superconductor or in the ferromagnet
significantly suppresses these oscillations. The calculated T_c(d_F)
dependences are compared with existing experimental data for Fe/Nb/Fe trilayers
and Nb/Co multilayers.Comment: 13 pages, REVTeX4, 8 PS-figures; improved version, submitted to PR
Magnetic Order and Fluctuations in the Presence of Quenched Disorder in the Kagome Staircase System (Co(1-x)Mg(x))3V2O8
Co3V2O8 is an orthorhombic magnet in which S=3/2 magnetic moments reside on
two crystallographically inequivalent Co2+ sites, which decorate a stacked,
buckled version of the two dimensional kagome lattice, the stacked kagome
staircase. The magnetic interactions between the Co2+ moments in this structure
lead to a complex magnetic phase diagram at low temperature, wherein it
exhibits a series of five transitions below 11 K that ultimately culminate in a
simple ferromagnetic ground state below T~6.2 K. Here we report magnetization
measurements on single and polycrystalline samples of (Co(1-x)Mg(x))3V2O8 for
x<0.23, as well as elastic and inelastic neutron scattering measurements on
single crystals of magnetically dilute (Co(1-x)Mg(x))3V2O8 for x=0.029 and
x=0.194, in which non-magnetic Mg2+ ions substitute for magnetic Co2+. We find
that a dilution of 2.9% leads to a suppression of the ferromagnetic transition
temperature by ~15% while a dilution level of 19.4% is sufficient to destroy
ferromagnetic long-range order in this material down to a temperature of at
least 1.5 K. The magnetic excitation spectrum is characterized by two spin-wave
branches in the ordered phase for (Co(1-x)Mg(x))3V2O8 (x=0.029), similar to
that of the pure x=0 material, and by broad diffuse scattering at temperatures
below 10 K in (Co(1-x)Mg(x))3V2O8 (x=0.194). Such a strong dependence of the
transition temperatures to long range order in the presence of quenched
non-magnetic impurities is consistent with two-dimensional physics driving the
transitions. We further provide a simple percolation model that
semi-quantitatively explains the inability of this system to establish
long-range magnetic order at the unusually-low dilution levels which we observe
in our experiments.Comment: 10 pages, 13 figure
- …