818 research outputs found
Depression and mortality: Artifact of measurement and analysis?
Background Previous research demonstrates various associations between depression, cardiovascular disease (CVD) incidence and mortality, possibly as a result of the different methodologies used to measure depression and analyse relationships. This analysis investigated the association between depression, CVD incidence (CVDI) and mortality from CVD (MCVD), smoking related conditions (MSRC), and all causes (MALL), in a sample data set, where depression was measured using items from a validated questionnaire and using items derived from the factor analysis of a larger questionnaire, and analyses were conducted based on continuous data and grouped data. Methods Data from the PRIME Study (N=9798 men) on depression and 10-year CVD incidence and mortality were analysed using Cox proportional hazards models. Results Using continuous data, both measures of depression resulted in the emergence of positive associations between depression and mortality (MCVD, MSRC, MALL). Using grouped data, however, associations between a validated measure of depression and MCVD, and between a measure of depression derived from factor analysis and all measures of mortality were lost. Limitations Low levels of depression, low numbers of individuals with high depression and low numbers of outcome events may limit these analyses, but levels are usual for the population studied. Conclusions These data demonstrate a possible association between depression and mortality but detecting this association is dependent on the measurement used and method of analysis. Different findings based on methodology present clear problems for the elucidation and determination of relationships. The differences here argue for the use of validated scales where possible and suggest against over-reduction via factor analysis and grouping. CrownCopyright © 2013PublishedbyElsevierB.V.Allrightsreserved
Energy levels of few electron quantum dots imaged and characterized by atomic force microscopy
Strong confinement of charges in few electron systems such as in atoms,
molecules and quantum dots leads to a spectrum of discrete energy levels that
are often shared by several degenerate quantum states. Since the electronic
structure is key to understanding their chemical properties, methods that probe
these energy levels in situ are important. We show how electrostatic force
detection using atomic force microscopy reveals the electronic structure of
individual and coupled self-assembled quantum dots. An electron addition
spectrum in the Coulomb blockade regime, resulting from a change in cantilever
resonance frequency and dissipation during tunneling events, shows one by one
electron charging of a dot. The spectra show clear level degeneracies in
isolated quantum dots, supported by the first observation of predicted
temperature-dependent shifts of Coulomb blockade peaks. Further, by scanning
the surface we observe that several quantum dots may reside on what
topologically appears to be just one. These images of grouped weakly and
strongly coupled dots allow us to estimate their relative coupling strengths.Comment: 11 pages, 6 figure
Do lifestyle behaviours explain socioeconomic differences in all-cause mortality, and fatal and non-fatal cardiovascular events? Evidence from middle aged men in France and Northern Ireland in the PRIME Study
Imaging Inter-Edge State Scattering Centers in the Quantum Hall Regime
We use an atomic force microscope tip as a local gate to study the scattering
between edge channels in a 2D electron gas in the quantum Hall regime. The
scattering is dominated by individual, microscopic scattering centers, which we
directly image here for the first time. The tip voltage dependence of the
scattering indicates that tunneling occurs through weak links and localized
states.Comment: 4 pages, 5 figure
A High Polyphenol Diet Improves Psychological Well-Being: The Polyphenol Intervention Trial (PPhIT).
Mental ill health is currently one of the leading causes of disease burden worldwide. A growing body of data has emerged supporting the role of diet, especially polyphenols, which have anxiolytic and antidepressant-like properties. The aim of the present study was to assess the effect of a high polyphenol diet (HPD) compared to a low polyphenol diet (LPD) on aspects of psychological well-being in the Polyphenol Intervention Trial (PPhIT). Ninety-nine mildly hypertensive participants aged 40-65 years were enrolled in a four-week LPD washout period and then randomised to either an LPD or an HPD for eight weeks. Both at baseline and the end of intervention, participants' lifestyle and psychological well-being were assessed. The participants in the HPD group reported a decrease in depressive symptoms, as assessed by the Beck Depression Inventory-II, and an improvement in physical component and mental health component scores as assessed with 36-Item Short Form Survey. No differences in anxiety, stress, self-esteem or body image perception were observed. In summary, the study findings suggest that the adoption of a polyphenol-rich diet could potentially lead to beneficial effects including a reduction in depressive symptoms and improvements in general mental health status and physical health in hypertensive participants
Effects of insulin-like growth factor 1 in preventing acute coronary syndromes: the PRIME Study
Single-Atom Gating of Quantum State Superpositions
The ultimate miniaturization of electronic devices will likely require local
and coherent control of single electronic wavefunctions. Wavefunctions exist
within both physical real space and an abstract state space with a simple
geometric interpretation: this state space--or Hilbert space--is spanned by
mutually orthogonal state vectors corresponding to the quantized degrees of
freedom of the real-space system. Measurement of superpositions is akin to
accessing the direction of a vector in Hilbert space, determining an angle of
rotation equivalent to quantum phase. Here we show that an individual atom
inside a designed quantum corral can control this angle, producing arbitrary
coherent superpositions of spatial quantum states. Using scanning tunnelling
microscopy and nanostructures assembled atom-by-atom we demonstrate how single
spins and quantum mirages can be harnessed to image the superposition of two
electronic states. We also present a straightforward method to determine the
atom path enacting phase rotations between any desired state vectors. A single
atom thus becomes a real space handle for an abstract Hilbert space, providing
a simple technique for coherent quantum state manipulation at the spatial limit
of condensed matter.Comment: Published online 6 April 2008 in Nature Physics; 17 page manuscript
(including 4 figures) + 3 page supplement (including 2 figures);
supplementary movies available at http://mota.stanford.ed
Partnerships to Address School Safety through a Student Support Lens
School safety is a primary concern of school leaders, employees, parents, and a variety of community stakeholders. Attempts to mitigate and prevent school safety concerns often focus on strategies around school climate assessment, emergency communication, school safety plan development, and school resource officer employment (U.S. DHS et al., 2018). Involvement of key stakeholders, such as school social workers, school counselors, and school-based mental health professionals is emphasized in creating and assessing school safety in a wholistic manner. This article provides an overview of a Trainings to Increase School Safety grant program that was implemented with public school stakeholders through partnerships between a university and five public school districts in the Southeastern North Carolina region
Scanned Potential Microscopy of Edge and Bulk Currents in the Quantum Hall Regime
Using an atomic force microscope as a local voltmeter, we measure the Hall
voltage profile in a 2D electron gas in the quantum Hall (QH) regime. We
observe a linear profile in the bulk of the sample in the transition regions
between QH plateaus and a distinctly nonlinear profile on the plateaus. In
addition, localized voltage drops are observed at the sample edges in the
transition regions. We interpret these results in terms of theories of edge and
bulk currents in the QH regime.Comment: 4 pages, 5 figure
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