2,192 research outputs found
Effects of steady state free precession parameters on cardiac mass, function, and volumes
G0400444/Medical Research Council/United Kingdom
Wellcome Trust/United Kingdo
Role of spin-orbit coupling on the spin triplet pairing in Na_{x}CoO_{2}yH_{2}O I: d-vector under zero magnetic field
The d-vector in possibile spin triplet superconductor Na_{x}CoO_{2}yH_{2}O is
microscopically investigated on the basis of the multi-orbital Hubbard model
including the atomic spin-orbit coupling. As a result of the perturbation
theory, we obtain the stable spin triplet superconductivity where the p-wave
and f-wave states can be stabilized. If we neglect the spin-orbit coupling,
superconducting state has 6-fold (3-fold) degeneracy in the p-wave (f-wave)
state. This degeneracy is lifted by the spin-orbit coupling. We determine the
d-vector within the linearlized Dyson-Gorkov equation. It is shown that the
d-vector is always along the plane when the pairing symmetry is p-wave, while
it depends on the parameters in case of the f-wave state. The lifting of
degeneracy is significant in the p-wave state while it is very small in the
f-wave state. This is because the first order term with respect to the
spin-orbit coupling is effective in the former case, while it is ineffective in
the latter case. The consistency of these results with NMR and \muSR
measurements are discussed.Comment: To appear in J. Phys. Soc. Jpn. 74 (2005) No.
Structural Insights into Triglyceride Storage Mediated by Fat Storage-Inducing Transmembrane (FIT) Protein 2
Fat storage-Inducing Transmembrane proteins 1 & 2 (FIT1/FITM1 and FIT2/FITM2) belong to a unique family of evolutionarily conserved proteins localized to the endoplasmic reticulum that are involved in triglyceride lipid droplet formation. FIT proteins have been shown to mediate the partitioning of cellular triglyceride into lipid droplets, but not triglyceride biosynthesis. FIT proteins do not share primary sequence homology with known proteins and no structural information is available to inform on the mechanism by which FIT proteins function. Here, we present the experimentally-solved topological models for FIT1 and FIT2 using N-glycosylation site mapping and indirect immunofluorescence techniques. These methods indicate that both proteins have six-transmembrane-domains with both N- and C-termini localized to the cytosol. Utilizing this model for structure-function analysis, we identified and characterized a gain-of-function mutant of FIT2 (FLL(157-9)AAA) in transmembrane domain 4 that markedly augmented the total number and mean size of lipid droplets. Using limited-trypsin proteolysis we determined that the FLL(157-9)AAA mutant has enhanced trypsin cleavage at K86 relative to wild-type FIT2, indicating a conformational change. Taken together, these studies indicate that FIT2 is a 6 transmembrane domain-containing protein whose conformation likely regulates its activity in mediating lipid droplet formation
Atherosclerosis profile and incidence of cardiovascular events: a population-based survey
<p>Abstract</p> <p>Background</p> <p>Atherosclerosis is a chronic progressive disease often presenting as clinical cardiovascular disease (CVD) events. This study evaluated the characteristics of individuals with a diagnosis of atherosclerosis and estimated the incidence of CVD events to assist in the early identification of high-risk individuals.</p> <p>Methods</p> <p>Respondents to the US SHIELD baseline survey were followed for 2 years to observe incident self-reported CVD. Respondents had subclinical atherosclerosis if they reported a diagnosis of narrow or blocked arteries/carotid artery disease without a past clinical CVD event (heart attack, stroke or revascularization). Characteristics of those with atherosclerosis and incident CVD were compared with those who did not report atherosclerosis at baseline but had CVD in the following 2 years using chi-square tests. Logistic regression model identified characteristics associated with atherosclerosis and incident events.</p> <p>Results</p> <p>Of 17,640 respondents, 488 (2.8%) reported having subclinical atherosclerosis at baseline. Subclinical atherosclerosis was associated with age, male gender, dyslipidemia, circulation problems, hypertension, past smoker, and a cholesterol test in past year (OR = 2.2) [all p < 0.05]. Incident CVD was twice as high in respondents with subclinical atherosclerosis (25.8%) as in those without atherosclerosis or clinical CVD (12.2%). In individuals with subclinical atherosclerosis, men (RR = 1.77, p = 0.050) and individuals with circulation problems (RR = 2.36, p = 0.003) were at greatest risk of experiencing CVD events in the next 2 years.</p> <p>Conclusion</p> <p>Self-report of subclinical atherosclerosis identified an extremely high-risk group with a >25% risk of a CVD event in the next 2 years. These characteristics may be useful for identifying individuals for more aggressive diagnostic and therapeutic efforts.</p
Probing quantum gravity using photons from a flare of the active galactic nucleus Markarian 501 observed by the MAGIC telescope
We analyze the timing of photons observed by the MAGIC telescope during a
flare of the active galactic nucleus Mkn 501 for a possible correlation with
energy, as suggested by some models of quantum gravity (QG), which predict a
vacuum refractive index \simeq 1 + (E/M_{QGn})^n, n = 1,2. Parametrizing the
delay between gamma-rays of different energies as \Delta t =\pm\tau_l E or
\Delta t =\pm\tau_q E^2, we find \tau_l=(0.030\pm0.012) s/GeV at the 2.5-sigma
level, and \tau_q=(3.71\pm2.57)x10^{-6} s/GeV^2, respectively. We use these
results to establish lower limits M_{QG1} > 0.21x10^{18} GeV and M_{QG2} >
0.26x10^{11} GeV at the 95% C.L. Monte Carlo studies confirm the MAGIC
sensitivity to propagation effects at these levels. Thermal plasma effects in
the source are negligible, but we cannot exclude the importance of some other
source effect.Comment: 12 pages, 3 figures, Phys. Lett. B, reflects published versio
Age and gender specific normal values of left ventricular mass, volume and function for gradient echo magnetic resonance imaging: a cross sectional study
<p>Abstract</p> <p>Background</p> <p>Knowledge about age-specific normal values for left ventricular mass (LVM), end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV) and ejection fraction (EF) by cardiac magnetic resonance imaging (CMR) is of importance to differentiate between health and disease and to assess the severity of disease. The aims of the study were to determine age and gender specific normal reference values and to explore the normal physiological variation of these parameters from adolescence to late adulthood, in a cross sectional study.</p> <p>Methods</p> <p>Gradient echo CMR was performed at 1.5 T in 96 healthy volunteers (11–81 years, 50 male). Gender-specific analysis of parameters was undertaken in both absolute values and adjusted for body surface area (BSA).</p> <p>Results</p> <p>Age and gender specific normal ranges for LV volumes, mass and function are presented from the second through the eighth decade of life. LVM, ESV and EDV rose during adolescence and declined in adulthood. SV and EF decreased with age. Compared to adult females, adult males had higher BSA-adjusted values of EDV (p = 0.006) and ESV (p < 0.001), similar SV (p = 0.51) and lower EF (p = 0.014). No gender differences were seen in the youngest, 11–15 year, age range.</p> <p>Conclusion</p> <p>LV volumes, mass and function vary over a broad age range in healthy individuals. LV volumes and mass both rise in adolescence and decline with age. EF showed a rapid decline in adolescence compared to changes throughout adulthood. These findings demonstrate the need for age and gender specific normal ranges for clinical use.</p
Attentional Prioritization of Infant Faces Is Limited to Own-Race Infants
Background: Recent evidence indicates that infant faces capture attention automatically, presumably to elicit caregiving behavior from adults and leading to greater probability of progeny survival. Elsewhere, evidence demonstrates that people show deficiencies in the processing of other-race relative to own-race faces. We ask whether this other-race effect impacts on attentional attraction to infant faces. Using a dot-probe task to reveal the spatial allocation of attention, we investigate whether other-race infants capture attention. Principal Findings: South Asian and White participants (young adults aged 18–23 years) responded to a probe shape appearing in a location previously occupied by either an infant face or an adult face; across trials, the race (South Asian/ White) of the faces was manipulated. Results indicated that participants were faster to respond to probes that appeared in the same location as infant faces than adult faces, but only on own-race trials. Conclusions/Significance: Own-race infant faces attract attention, but other-race infant faces do not. Sensitivity to facespecific care-seeking cues in other-race kindenschema may be constrained by interracial contact and experience
Mechanical, electrical and electro-mechanical properties of thermoplastic elastomer styrene–butadiene–styrene/multiwall carbon nanotubes composites
Composites of styrene-butadiene-styrene (SBS) block copolymer with multiwall carbon
nanotubes (MWCNT) were processed by solution casting in order to investigate the
influence of filler content, the different ratio of styrene/butadiene in the copolymer and
the architecture of the SBS matrix on the electrical, mechanical and electro-mechanical
properties of the composites. It was found that filler content and elastomer matrix
architecture influence the percolation threshold and consequently the overall composite
electrical conductivity. The mechanical properties are mainly affected by the styrene
and filler content. Hopping between nearest fillers is proposed as the main mechanism
for the composite conduction. The variation of the electrical resistivity is linear with the
deformation. This fact, together with the gauge factor values in the range of 2 to 18,
results in appropriate composites to be used as (large) deformation sensors.This work was funded by FEDER funds through the "Programa Operacional Factores de
Competitividade – COMPETE" and by national funds by FCT - Fundação para a
Ciência e a Tecnologia, through project references PTDC/CTM/69316/2006,
PTDC/CTM/73465/2006, PTDC/CTM-NAN/112574/2009, and NANO/NMed-
SD/0156/2007. PC, JS and VS also thank FCT for the SFRH/BD/64267/2009,
SFRH/BD/60623/2009 and SFRH/BPD/63148/2009 grants, respectively. The authors
also thank support from the COST Action MP1003 ”European Scientific Network for
Artificial Muscles” and the COST action MP0902 “Composites of Inorganic Nanotubes
and Polymers (COINAPO)
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