1,479 research outputs found
Identifying lifestyle factors associated to co-morbidity of obesity and psychiatric disorders, a pilot study
Obesity and psychiatric disorders are linked through a bidirectional association. Obesity rates have tripled globally in the past decades, and it is predicted that by 2025, one billion people will be affected by obesity, often with a co-morbidity such as depression. While this co-morbidity seems to be a global health issue, lifestyle factors associated to it differ between countries and are often attributed to more than one factor. Prior obesity studies were performed in Western populations; this is the first study that investigates lifestyle factors relating to obesity and mental health of the diverse population in Qatar, a country that has witnessed tremendous lifestyle change in a short time. In this pilot study, we surveyed 379 respondents to assess and compare the lifestyles of Qatar residents to the global population. However due to the high proportion of responses from the United Kingdom (UK) residents, we have made comparisons between Qatar residents and UK residents. We used chi-square analysis, spearman rank correlation and logistic regression to compare the lifestyle factors of individuals suffering from both increased BMI and mental health conditions. The types of food consumed, stress, exercise frequency and duration, alcohol and tobacco consumption, and sleep duration, were explored and results argue that different lifestyle factors can contribute to the same health condition, suggesting different mechanisms involved. We found that both groups reported similar sleep durations (p = 0.800), but that perception of sleep (p = 0.011), consumption of alcohol (p = 0.001), consumption of takeaway food (p = 0.007), and physical activity significantly varied between the groups (p = 0.0001). The study examined the predictors of comorbidity in Qatar as well as UK populations using multivariate logistic regression analysis. The result of the study showed no statistical association between comorbidity and the predictors drinking habit, smoking, physical activity, vegetable consumption, eat outs, and sleep perception for the Qatar population, and for the combined population. This study, however showed a significant association (p = 0.033) between sleep perception and comorbidity for the UK population. We conclude that further analysis is needed to understand the relationship between specific lifestyle factors and multimorbidity in each country
Higher order glass-transition singularities in colloidal systems with attractive interactions
The transition from a liquid to a glass in colloidal suspensions of particles
interacting through a hard core plus an attractive square-well potential is
studied within the mode-coupling-theory framework. When the width of the
attractive potential is much shorter than the hard-core diameter, a reentrant
behavior of the liquid-glass line, and a glass-glass-transition line are found
in the temperature-density plane of the model. For small well-width values, the
glass-glass-transition line terminates in a third order bifurcation point, i.e.
in a A_3 (cusp) singularity. On increasing the square-well width, the
glass-glass line disappears, giving rise to a fourth order A_4 (swallow-tail)
singularity at a critical well width. Close to the A_3 and A_4 singularities
the decay of the density correlators shows stretching of huge dynamical
windows, in particular logarithmic time dependence.Comment: 19 pages, 12 figures, Phys. Rev. E, in prin
What are the interactions in quantum glasses?
The form of the low-temperature interactions between defects in neutral
glasses is reconsidered. We analyse the case where the defects can be modelled
either as simple 2-level tunneling systems, or tunneling rotational impurities.
The coupling to strain fields is determined up to 2nd order in the displacement
field. It is shown that the linear coupling generates not only the usual
Ising-like interaction between the rotational tunneling defect modes,
which cause them to freeze around a temperature , but also a random field
term. At lower temperatures the inversion symmetric tunneling modes are still
active - however the coupling of these to the frozen rotational modes, now via
the 2nd-order coupling to phonons, generates another random field term acting
on the inversion symmetric modes (as well as shorter-range interactions
between them). Detailed expressions for all these couplings are given.Comment: 12 pages, 2 figures. Minor modifications, published versio
Path integral Monte Carlo simulation of charged particles in traps
This chapter is devoted to the computation of equilibrium (thermodynamic)
properties of quantum systems. In particular, we will be interested in the
situation where the interaction between particles is so strong that it cannot
be treated as a small perturbation. For weakly coupled systems many efficient
theoretical and computational techniques do exist. However, for strongly
interacting systems such as nonideal gases or plasmas, strongly correlated
electrons and so on, perturbation methods fail and alternative approaches are
needed. Among them, an extremely successful one is the Monte Carlo (MC) method
which we are going to consider in this chapter.Comment: 18 pages, based on talks on Hareaus school on computational methods,
Greifswald, September 200
The Case for Optically-Thick High Velocity Broad Line Region Gas in Active Galactic Nuclei
A combined analysis of the profiles of the main broad quasar emission lines
in both Hubble Space Telescope and optical spectra shows that while the
profiles of the strong UV lines are quite similar, there is frequently a strong
increase in the Ly-alpha/H-alpha ratio in the high-velocity gas. We show that
the suggestion that the high velocity gas is optically-thin presents many
problems. We show that the relative strengths of the high velocity wings arise
naturally in an optically-thick BLR component. An optically-thick model
successfully explains the equivalent widths of the lines, the Ly-alpha/H-alpha
ratios and flatter Balmer decrements in the line wings, the strengths of CIII]
and the lambda 1400 blend, and the strong variability of high-velocity,
high-ionization lines (especially HeII and HeI).Comment: 34 pages in AASTeX, including 10 pages of figures. Submitted to
Astrophysical Journa
Pressure induced structural and dynamical changes in liquid Si. An ab-initio study
The static and dynamic properties of liquid Si at high-pressure have been
studied using the orbital free ab-initio molecular dynamics method. Four
thermodynamic states at pressures 4, 8, 14 and 23 GPa are considered. The
calculated static structure shows qualitative agreement with the available
experimental data. We analize the remarkable structural changes occurring
between 8 and 14 GPa along with its effect on several dynamic properties.Comment: 10 pages, 11 figures. Accepted for publication in Journal of Physics:
Condensed Matte
The End of the Lines for OX 169: No Binary Broad-Line Region
We show that unusual Balmer emission line profiles of the quasar OX 169,
frequently described as either self-absorbed or double peaked, are actually
neither. The effect is an illusion resulting from two coincidences. First, the
forbidden lines are quite strong and broad. Consequently, the [N II]6583 line
and the associated narrow-line component of H-alpha present the appearance of
twin H-alpha peaks. Second, the redshift of 0.2110 brings H-beta into
coincidence with Na I D at zero redshift, and ISM absorption in Na I D divides
the H-beta emission line. In spectra obtained over the past decade, we see no
substantial change in the character of the line profiles, and no indication of
intrinsic double-peaked structure. The H-gamma, Mg II, and Ly-alpha emission
lines are single peaked, and all of the emission-line redshifts are consistent
once they are correctly attributed to their permitted and forbidden-line
identifications. A systematic shift of up to 700 km/s between broad and narrow
lines is seen, but such differences are common, and could be due to
gravitational and transverse redshift in a low-inclination disk. Stockton &
Farnham (1991) had called attention to an apparent tidal tail in the host
galaxy of OX 169, and speculated that a recent merger had supplied the nucleus
with a coalescing pair of black holes which was now revealing its existence in
the form of two physically distinct broad-line regions. Although there is no
longer any evidence for two broad emission-line regions in OX 169, binary black
holes should form frequently in galaxy mergers, and it is still worthwhile to
monitor the radial velocities of emission lines which could supply evidence of
their existence in certain objects.Comment: 19 pages, 5 figures, accepted for publication in Ap.
Pinning/depinning of crack fronts in heterogeneous materials
The fatigue fracture surfaces of a metallic alloy, and the stress corrosion
fracture surfaces of glass are investigated as a function of crack velocity. It
is shown that in both cases, there are two fracture regimes, which have a well
defined self-affine signature. At high enough length scales, the universal
roughness index 0.78 is recovered. At smaller length scales, the roughness
exponent is close to 0.50. The crossover length separating these two
regimes strongly depends on the material, and exhibits a power-law decrease
with the measured crack velocity , with . The exponents and characterising the dependence of
and upon the pulling force are shown to be close to and
.Comment: 4 pages, latex, and 4 encapsulated postscript figure
- âŠ