764 research outputs found
Recovery from addiction: Behavioral economics and value-based decision making.
Behavioral economics provides a general framework to explain the shift in behavioral allocation from substance use to substance-free activities that characterizes recovery from addiction, but it does not attempt to explain the internal processes that prompt those behavioral changes. In this article we outline a novel analysis of addiction recovery based on computational work on value-based decision making (VBDM), which can explain how people with addiction are able to overcome the reinforcement pathologies and decision-making vulnerabilities that characterize the disorder. The central tenet of this account is that shifts in molar reinforcer preferences over time from substance use to substance-free activities can be attributed to changes in evidence accumulation rates and response thresholds in the context of choices involving substance use and substance-free alternatives. We discuss how this account can be reconciled with the established mechanisms of action of psychosocial interventions for addiction and demonstrate how it has the potential to empirically address longstanding debates regarding the nature of impairments to self-control in addiction. We also highlight conceptual and methodological issues that require careful consideration in translating VBDM to addiction and recovery
Electronic Properties of Ultra-Thin Aluminum Nanowires
We have carried out first principles electronic structure and total energy
calculations for a series of ultrathin aluminum nanowires, based on structures
obtained by relaxing the model wires of Gulseren et al. The number of
conducting channels is followed as the wires radius is increased. The results
suggest that pentagonal wires should be detectable, as the only ones who can
yield a channel number between 8 and 10.Comment: 9 pages + 3 figures, to appear on Surface Scienc
Metal-insulator transition and charge ordering in the extended Hubbard model at one-quarter filling
We study with exact diagonalization the zero temperature properties of the
quarter-filled extended Hubbard model on a square lattice. We find that
increasing the ratio of the intersite Coulomb repulsion, , to the band width
drives the system from a metal to a charge ordered insulator. The evolution of
the optical conductivity spectrum with increasing is compared to the
observed optical conductivity of several layered molecular crystals with the
theta and beta'' crystal structures.Comment: 5 pages, 3 figure
Pentagonal nanowires: a first-principles study of atomic and electronic structure
We performed an extensive first-principles study of nanowires in various
pentagonal structures by using pseudopotential plane wave method within the
density functional theory. Our results show that nanowires of different types
of elements, such as alkali, simple, transition and noble metals and inert gas
atoms, have a stable structure made from staggered pentagons with a linear
chain perpendicular to the planes of the pentagons and passing through their
centers. This structure exhibits bond angles close to those in the icosahedral
structure. However, silicon is found to be energetically more favorable in the
eclipsed pentagonal structure. These quasi one dimensional pentagonal nanowires
have higher cohesive energies than many other one dimensional structures and
hence may be realized experimentally. The effect of magnetic state are examined
by spin-polarized calculations. The origin of the stability are discussed by
examining optimized structural parameters, charge density and electronic band
structure, and by using analysis based on the empirical Lennard-Jones type
interaction. Electronic band structure of pentagonal wires of different
elements are discussed and their effects on quantum ballistic conductance are
mentioned. It is found that the pentagonal wire of silicon exhibits metallic
band structure.Comment: 4 figures, accepted for publication in Phys. Rev.
Energetics, forces, and quantized conductance in jellium modeled metallic nanowires
Energetics and quantized conductance in jellium modeled nanowires are
investigated using the local density functional based shell correction method,
extending our previous study of uniform in shape wires [C. Yannouleas and U.
Landman, J. Phys. Chem. B 101, 5780 (1997)] to wires containing a variable
shaped constricted region. The energetics of the wire (sodium) as a function of
the length of the volume conserving, adiabatically shaped constriction leads to
formation of self selecting magic wire configurations. The variations in the
energy result in oscillations in the force required to elongate the wire and
are directly correlated with the stepwise variations of the conductance of the
nanowire in units of 2e^2/h. The oscillatory patterns in the energetics and
forces, and the correlated stepwise variation in the conductance are shown,
numerically and through a semiclassical analysis, to be dominated by the
quantized spectrum of the transverse states at the narrowmost part of the
constriction in the wire.Comment: Latex/Revtex, 11 pages with 5 Postscript figure
Fertility, Living Arrangements, Care and Mobility
There are four main interconnecting themes around which the contributions in this book are based. This introductory chapter aims to establish the broad context for the chapters that follow by discussing each of the themes. It does so by setting these themes within the overarching demographic challenge of the twenty-first century – demographic ageing. Each chapter is introduced in the context of the specific theme to which it primarily relates and there is a summary of the data sets used by the contributors to illustrate the wide range of cross-sectional and longitudinal data analysed
Genome-wide association study of kidney function decline in individuals of European descent.
Genome-wide association studies (GWASs) have identified multiple loci associated with cross-sectional eGFR, but a systematic genetic analysis of kidney function decline over time is missing. Here we conducted a GWAS meta-analysis among 63,558 participants of European descent, initially from 16 cohorts with serial kidney function measurements within the CKDGen Consortium, followed by independent replication among additional participants from 13 cohorts. In stage 1 GWAS meta-analysis, single-nucleotide polymorphisms (SNPs) at MEOX2, GALNT11, IL1RAP, NPPA, HPCAL1, and CDH23 showed the strongest associations for at least one trait, in addition to the known UMOD locus, which showed genome-wide significance with an annual change in eGFR. In stage 2 meta-analysis, the significant association at UMOD was replicated. Associations at GALNT11 with Rapid Decline (annual eGFR decline of 3 ml/min per 1.73 m(2) or more), and CDH23 with eGFR change among those with CKD showed significant suggestive evidence of replication. Combined stage 1 and 2 meta-analyses showed significance for UMOD, GALNT11, and CDH23. Morpholino knockdowns of galnt11 and cdh23 in zebrafish embryos each had signs of severe edema 72 h after gentamicin treatment compared with controls, but no gross morphological renal abnormalities before gentamicin administration. Thus, our results suggest a role in the deterioration of kidney function for the loci GALNT11 and CDH23, and show that the UMOD locus is significantly associated with kidney function decline.Kidney International advance online publication, 10 December 2014; doi:10.1038/ki.2014.361
- …