821 research outputs found
How accurately do adult sons and daughters report and perceive parental deaths from coronary disease?
<b>OBJECTIVES</b>: To describe how adult sons and daughters report and perceive parental deaths from heart disease
<b>DESIGN</b>: Two generation family study.
<b>SETTING</b>: West of Scotland.
<b>SUBJECTS</b>: 1040 sons and 1298 daughters aged 30-59 from 1477 families, whose fathers and mothers were aged 45-64 in 1972-76 and have been followed up for mortality over 20 years.
<b>OUTCOME</b> : Perception of a "family weakness" attributable to heart disease.
RESULTS : 26% of sons and daughters had a parent who had died of coronary heart disease (CHD). The proportion was higher in older offspring (+18% per 10 year age difference) and in manual compared with non-manual groups (+37%). Eighty nine per cent of parental deaths from CHD were correctly reported by offspring. Only 23% of sons and 34% of daughters with at least one parent who had died of CHD considered that they had a family weakness attributable to heart disease. Perceptions of a family weakness were higher when one or both parents had died of CHD, when parental deaths occurred at a younger age, in daughters compared with sons and in offspring in non-manual compared with manual occupations.
<b>CONCLUSIONS</b>: Only a minority of sons and daughters with experience of a parent having died from CHD perceive this in terms of a family weakness attributable to heart disease. Although men in manual occupations are most likely to develop CHD, they are least likely to interpret a parental death from CHD in terms of a family weakness. Health professionals giving advice to patients on their familial risks need to be aware of the difference between clinical definitions and lay perceptions of a family history of heart disease
The quasi-linear relaxation of thick-target electron beams in solar flares
The effects of quasi-linear interactions on thick-target electron beams in the solar corona are investigated. Coulomb collisions produce regions of positive gradient in electron distributions which are initially monotonic decreasing functions of energy. In the resulting two-stream instability, energy and momentum are transferred from electrons to Langmuir waves and the region of positive slope in the electron distribution is replaced by a plateau. In the corona, the timescale for this quasi-linear relaxation is very short compared to the collision time. It is therefore possible to model the effects of quasi-linear relaxation by replacing any region of positive slop in the distribution by a plateau at each time step, in such a way as to conserve particle number. The X-ray bremsstrahlung and collisional heating rate produced by a relaxed beam are evaluated. Although the analysis is strictly steady state, it is relevant to the theoretical interpretation of hard X-ray bursts with durations of the order of a few seconds (i.e., the majority of such bursts)
Fast electron slowing-down and diffusion in a high temperature coronal X-ray source
Finite thermal velocity modifications to electron slowing-down rates may be important for the deduction of solar flare total electron energy. Here we treat both slowing-down and velocity diffusion of electrons in the corona at flare temperatures, for the case of a simple, spatially homogeneous source. Including velocity diffusion yields a consistent treatment of both "accelerated" and "thermal" electrons. It also emphasises that one may not invoke finite thermal velocity target effects on electron lifetimes without simultaneously treating the contribution to the observed X-ray spectrum from thermal electrons. We present model calculations of the X-ray spectra resulting from injection of a power-law energy distribution of electrons into a source with finite temperature. Reducing the power-law distribution low-energy cutoff to lower and lower energies only increases the relative magnitude of the thermal component of the spectrum, because the lowest energy electrons simply join the background thermal distribution. Acceptable fits to RHESSI flare data are obtained using this model. These also demonstrate, however, that observed spectra may in consequence be acceptably consistent with rather a wide range of injected electron parameters
Normalization of boutique two-color microarrays with a high proportion of differentially expressed probes
Normalization is critical for removing systematic variation from microarray data. For two-color microarray platforms, intensity-dependent lowess normalization is commonly used to correct relative gene expression values for biases. Here we outline a normalization method for use when the assumptions of lowess normalization fail. Specifically, this can occur when specialized boutique arrays are constructed that contain a subset of genes selected to test particular biological functions
A Systematic Examination of Particle Motion in a Collapsing Magnetic Trap Model for Solar Flares
Context. It has been suggested that collapsing magnetic traps may contribute
to accelerating particles to high energies during solar flares.
Aims. We present a detailed investigation of the energization processes of
particles in collapsing magnetic traps, using a specific model. We also compare
for the first time the energization processes in a symmetric and an asymmetric
trap model.
Methods. Particle orbits are calculated using guiding centre theory. We
systematically investigate the dependence of the energization process on
initial position, initial energy and initial pitch angle.
Results. We find that in our symmetric trap model particles can gain up to
about 50 times their initial energy, but that for most initial conditions the
energy gain is more moderate. Particles with an initial position in the weak
field region of the collapsing trap and with pitch angles around 90 degrees
achieve the highest energy gain, with betatron acceleration of the
perpendicular energy the dominant energization mechanism. For particles with
smaller initial pitch angle, but still outside the loss cone, we find the
possibility of a significant increase in parallel energy. This increase in
parallel energy can be attributed to the curvature term in the parallel
equation of motion and the associated energy gain happens in the center of the
trap where the field line curvature has its maximum. We find qualitatively
similar results for the asymmetric trap model, but with smaller energy gains
and a larger number of particles escaping from the trap.Comment: 11 pages, 13 figures. To be published in Astronomy and Astrophysic
The Solar Photospheric-to-Coronal Fe abundance from X-ray Fluorescence Lines
The ratio of the Fe abundance in the photosphere to that in coronal flare
plasmas is determined by X-ray lines within the complex at 6.7~keV (1.9~\AA)
emitted during flares. The line complex includes the He-like Fe (\fexxv)
resonance line (6.70~keV) and Fe K lines (6.39, 6.40~keV), the
latter being primarily formed by the fluorescence of photospheric material by
X-rays from the hot flare plasma. The ratio of the Fe K lines to the
\fexxv\ depends on the ratio of the photospheric-to-flare Fe abundance,
heliocentric angle of the flare, and the temperature of the
flaring plasma. Using high-resolution spectra from X-ray spectrometers on the
{\em P78-1} and {\em Solar Maximum Mission} spacecraft, the Fe abundance in
flares is estimated to be and times the photospheric
Fe abundance, the {\em P78-1} value being preferred as it is more directly
determined. This enhancement is consistent with results from X-ray spectra from
the {\em RHESSI} spacecraft, but is significantly less than a factor 4 as in
previous work.Comment: Accepted for publication by MNRA
The effect of wave-particle interactions on low energy cutoffs in solar flare electron spectra
Solar flare hard X-ray spectra from RHESSI are normally interpreted in terms
of purely collisional electron beam propagation, ignoring spatial evolution and
collective effects. In this paper we present self-consistent numerical
simulations of the spatial and temporal evolution of an electron beam subject
to collisional transport and beam-driven Langmuir wave turbulence. These
wave-particle interactions represent the background plasma's response to the
electron beam propagating from the corona to chromosphere and occur on a far
faster timescale than coulomb collisions. From these simulations we derive the
mean electron flux spectrum, comparable to such spectra recovered from high
resolution hard X-rays observations of solar flares with RHESSI. We find that a
negative spectral index (i.e. a spectrum that increases with energy), or local
minima when including the expected thermal spectral component at low energies,
occurs in the standard thick-target model, when coulomb collisions are only
considered. The inclusion of wave-particle interactions does not produce a
local minimum, maintaining a positive spectral index. These simulations are a
step towards a more complete treatment of electron transport in solar flares
and suggest that a flat spectrum (spectral index of 0 to 1) down to thermal
energies maybe a better approximation instead of a sharp cut-off in the
injected electron spectrum.Comment: 6 pages, 5 figures, accepted by ApJ
Sparkling extreme-ultraviolet bright dots observed with Hi-C
Observing the Sun at high time and spatial scales is a step toward understanding the finest and fundamental scales of heating events in the solar corona. The high-resolution coronal (Hi-C) instrument has provided the highest spatial and temporal resolution images of the solar corona in the EUV wavelength range to date. Hi-C observed an active region on 2012 July 11 that exhibits several interesting features in the EUV line at 193 Å. One of them is the existence of short, small brightenings "sparkling" at the edge of the active region; we call these EUV bright dots (EBDs). Individual EBDs have a characteristic duration of 25 s with a characteristic length of 680 km. These brightenings are not fully resolved by the SDO/AIA instrument at the same wavelength; however, they can be identified with respect to the Hi-C location of the EBDs. In addition, EBDs are seen in other chromospheric/coronal channels of SDO/AIA, which suggests a temperature between 0.5 and 1.5 MK. Based on their frequency in the Hi-C time series, we define four different categories of EBDs: single peak, double peak, long duration, and bursty. Based on a potential field extrapolation from an SDO/HMI magnetogram, the EBDs appear at the footpoints of large-scale, trans-equatorial coronal loops. The Hi-C observations provide the first evidence of small-scale EUV heating events at the base of these coronal loops, which have a free magnetic energy of the order of 1026 erg. © 2014. The American Astronomical Society. All rights reserved
“Availability is the poor cousin of marketing and pricing”: qualitative study of stakeholders’ views on policy priorities around tobacco and alcohol availability
Background: Reducing alcohol and tobacco availability is one potential way to reduce harm from these unhealthy commodities. This study explores key stakeholders’ views in relation to policy priorities and considerations for both alcohol and tobacco availability. Methods: We conducted semi-structured interviews with 14 stakeholders from alcohol and/or tobacco third sector organizations, government, public health and licensing in Scotland. Interviews explored their views on alcohol/tobacco availability, including its place in the policy landscape and experiences in gaining support for policies. Data were analyzed using thematic analysis. Results: Stakeholders believed that alcohol and tobacco availability have not received as much policy attention as pricing and marketing. Stakeholders highlighted the importance of public support and having sufficient evidence to inform policy. Key considerations for future policies include: drawing on lessons from tobacco control policies to address alcohol availability, considering different aspects of availability (especially online availability), ensuring policies reflect their local context, considering the impact of policies on children, and managing retailers’ involvement in the policy process. Conclusion: This study highlights key considerations for policies to address alcohol and tobacco availability. There is a need for more research to consider retailers’ views and provide greater detail on specific policy suggestions.</p
winTEr SUrvivOrShiP anD SiTE fiDEliTy Of nElSOn'S, SalTMarSh, anD SEaSiDE SParrOwS in nOrTh CarOlina
Abstract. Three species of coastal sparrows (Ammodramus nelsoni, nelson's Sparrow; A. caudacutus, Saltmarsh Sparrow; and A. maritimus, Seaside Sparrow) reside in north Carolina salt marshes in winter during their nonbreeding periods. we analyzed the timing of migration, survivorship, and site fidelity of these species with mark-recapture data from five winters (2006)(2007)(2008)(2009)(2010). By determining the percentage of individuals captured more than once, we documented a shift from transient to settled individuals during and following migration and used linear regressions to test whether this shift was related to mean monthly minimum temperatures. we also used MarK and capture histories over five winters to estimate probabilities of apparent survival and capture. On the basis of recapture data, the three species' populations were composed largely of transient individuals from October until the sparrows settled for the winter by late november. Our recapture data indicate that when coastal sparrows settle for the winter or return to the region in a subsequent year, they do so with high site fidelity. we found that the percent of nelson's and Seaside sparrows captured more than once had a negative relationship with mean monthly minimum temperature. we estimated survival of nelson's, Saltmarsh, and Seaside sparrows at 0.673, 0.520, and 0.483, respectively. Our data indicate that survival of these coastal sparrows through the nonbreeding season is comparable to existing estimates for their breeding populations. Surveys in the nonbreeding season and management plans should take into account the likely presence of a large proportion of transient individuals during migration. Resumen. Tres especies de gorrión, Ammodramus nelsoni, A. caudacutus y A. maritimus, residen en el invierno en las marismas de Carolina del norte, durante sus periodos no reproductivos. analizamos el momento de migración, la supervivencia y la fidelidad de sitio de estas especies con datos de captura-recaptura provenientes de cinco inviernos (2006)(2007)(2008)(2009)(2010). Mediante la determinación del porcentaje de individuos capturados más de una vez, documentamos un cambio de individuos transitorios a individuos establecidos durante y luego de la migración. luego, usamos regresiones lineales para evaluar si este cambio estuvo relacionado con las temperaturas mínimas medias mensuales. También usamos MarK e historias de captura a lo largo de cinco inviernos para estimar las probabilidades de supervivencia aparente y de captura. Sobre la base de los datos de recaptura, las poblaciones de las tres especies estuvieron compuestas principalmente por individuos transitorios desde octubre hasta que los gorriones se establecieron para pasar el invierno a finales de noviembre. nuestros datos de recaptura indicaron que cuando los gorriones de las especies estudiadas se establecen para pasar el invierno o regresan a la región en un año subsecuente, lo hacen exhibiendo una alta fidelidad de sitio. Encontramos que el porcentaje de individuos de A. nelsoni y A. maritimus capturados más de una vez tuvieron una relación negativa con la temperatura mínima media mensual. Estimamos la supervivencia de los individuos de A. nelsoni, A. caudacutus y A. maritimus en 0.673, 0.520 y 0.483, respectivamente. nuestros datos indican que la supervivencia de estas especies a lo largo de la estación no reproductiva es comparable con los estimados existentes para sus poblaciones reproductivas. los muestreos en la estación no reproductiva y los planes de manejo deberían considerar la presencia probable de una gran proporción de individuos transitorios durante la migración
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