7,466 research outputs found
Controversies about a common etiology for eating and mood disorders.
Obesity and depression represent a growing health concern worldwide. For many years, basic science and medicine have considered obesity as a metabolic illness, while depression was classified a psychiatric disorder. Despite accumulating evidence suggesting that obesity and depression may share commonalities, the causal link between eating and mood disorders remains to be fully understood. This etiology is highly complex, consisting of multiple environmental and genetic risk factors that interact with each other. In this review, we sought to summarize the preclinical and clinical evidence supporting a common etiology for eating and mood disorders, with a particular emphasis on signaling pathways involved in the maintenance of energy balance and mood stability, among which orexigenic and anorexigenic neuropeptides, metabolic factors, stress responsive hormones, cytokines, and neurotrophic factors
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Analysing passenger arrivals rates and waiting time at bus stops
The present study investigates the rather under-explored topic of passenger waiting times at public transport facilities. Using data collected from part of London’s bus network by means of physical counts, measurements and observations, and complemented by on-site passenger interviews, the waiting behaviour is analysed for a number of bus stops served by different numbers of lines. The analysis employs a wide range of statistical methods and tools, and concentrates on three aspects: passenger interarrival time, passenger actual waiting time, and passenger perceived waiting time. The results suggest that there is a clear difference in terms of the passenger arrivals rate between stops served by up to two lines and stops served by three lines or more, as it appears that passengers in the former time their arrival at the stop to coincide with bus arrivals as much as possible. Also, it is found that waiting time at such stops is best approximated by the exponential distribution, with the gamma distribution also offering an adequate fit. Finally, as concerns the passengers’ perception of waiting time, it is found that this follows a lognormal or a gamma distribution, and generally overestimates the actual waiting time; however, this effect fades as the actual waiting time increases
Where does the gas fueling star formation in BCGs originate?
We investigate the relationship between X-ray cooling and star formation in
brightest cluster galaxies (BCGs). We present an X-ray spectral analysis of the
inner regions, 10-40 kpc, of six nearby cool core clusters (z<0.35) observed
with Chandra ACIS. This sample is selected on the basis of the high star
formation rate (SFR) observed in the BCGs. We restrict our search for cooling
gas to regions that are roughly cospatial with the starburst. We fit single-
and multi-temperature mkcflow models to constrain the amount of isobarically
cooling intracluster medium (ICM). We find that in all clusters, below a
threshold temperature ranging between 0.9 and 3 keV, only upper limits can be
obtained. In four out of six objects, the upper limits are significantly below
the SFR and in two, namely A1835 and A1068, they are less than a tenth of the
SFR. Our results suggests that a number of mechanisms conspire to hide the
cooling signature in our spectra. In a few systems the lack of a cooling
signature may be attributed to a relatively long delay time between the X-ray
cooling and the star burst. However, for A1835 and A1068, where the X-ray
cooling time is shorter than the timescale of the starburst, a possible
explanation is that the region where gas cools out of the X-ray phase extends
to very large radii, likely beyond the core of these systems.Comment: to appear in A&
Experimental Determination of the 1 Sigma(+) State Electric-Dipole-Moment Function of Carbon Monoxide up to a Large Internuclear Separation
Experimental intensity information is combined with numerically obtained vibrational wave functions in a nonlinear least squares fitting procedure to obtain the ground electronic state electric-dipole-moment function of carbon monoxide valid in the range of nuclear oscillation (0.87 to 1.01 A) of about the V = 38th vibrational level. Mechanical anharmonicity intensity factors, H, are computed from this function for delta V + = 1, 2, 3, with or = to 38
Radio polarimetry of compact steep spectrum sources at sub-arcsecond resolution
Aims - We report new Very Large Array polarimetric observations of Compact
Steep-Spectrum (CSS) sources at 8.4, 15, and 23GHz. Methods - Using
multi-frequency VLA observations we have derived sub-arcsecond resolution
images of the total intensity, polarisation, and rotation measure (RM)
distributions. Results heading - We present multi-frequency VLA polarisation
observations of CSS sources. About half of the sources are point-like even at
the resolution of about 0.1x0.1 arcseconds. The remaining sources have double
or triple structure. Low values for the percentage of polarised emission in CSS
sources is confirmed. On the average, quasars are more polarised than galaxies.
A wide range of RM values have been measured. There are clear indications of
very large RMs up to 5\,585 rad m**(-2). CSS galaxies are characterized by RM
values that are larger than CSS quasars. The majority of the objects show very
large values of RM. Conclusions - The available data on sub-arcsecond-scale
rest-frame RM estimates for CSS sources show that these have a wide range of
values extending up to about 36,000 rad m**(-2). RM estimates indicate an
overall density of the magneto-ionic medium larger than classical radio
sources.Comment: Accepted for publication by Astronomy & Astrophysic
A muon source based on plasma accelerators
The conceptual design of a compact source of GeV-class muons is presented,
based on a plasma based electron-gamma collider. Evaluations of muon flux,
spectra and brilliance are presented, carried out with ad-hoc montecarlo
simulations of the electron-gamma collisions. These are analyzed in the context
of a large spread of the invariant mass in the e-gamma interaction, due to the
typical characteristics of plasma self-injected GeV electron beams, carrying
large bunch charges with huge energy spread. The availability of a compact
point-like muon source, triggerable at nsec level, may open a completely new
scenario in the muon radiography application field
Modifications biochimiques dans l'écorce de divers plants d'agrumes atteints d'Exocortis
Les auteurs ont étudié les acides aminés et les acides organiques dans l'écorce de Lime Rangpur, de lime Kusaïe, de Redling mung et de Poncirus trifoliata, atteints ou non atteints des symptômes corticaux attribués par MOREIRA et par ROSSETTI à l'Exocortis. Ces travaux ont mis en évidence une diminution de l'arginine et de l'acide malique et une augmentation de l'acide citrique dans l'écorce "malade" par rapport à l'écorce normale. La plus faible teneur en arginine de l'écorce malade semble être la différence biochimique la plus significative entre l'écorce normale et l'écorce atteinte des symptômes d'Exocortis, en ce qui concerne les composés étudié
Electron beam transfer line design for plasma driven Free Electron Lasers
Plasma driven particle accelerators represent the future of compact
accelerating machines and Free Electron Lasers are going to benefit from these
new technologies. One of the main issue of this new approach to FEL machines is
the design of the transfer line needed to match of the electron-beam with the
magnetic undulators. Despite the reduction of the chromaticity of plasma beams
is one of the main goals, the target of this line is to be effective even in
cases of beams with a considerable value of chromaticity. The method here
explained is based on the code GIOTTO [1] that works using a homemade genetic
algorithm and that is capable of finding optimal matching line layouts directly
using a full 3D tracking code.Comment: 9 Pages, 4 Figures. A related poster was presented at EAAC 201
The XMM Cluster Outskirts Project (X-COP): Physical conditions to the virial radius of Abell 2142
Context. Galaxy clusters are continuously growing through the accretion of
matter in their outskirts. This process induces inhomogeneities in the gas
density distribution (clumping) which need to be taken into account to recover
the physical properties of the intracluster medium (ICM) at large radii. Aims.
We studied the thermodynamic properties in the outskirts (R > R500) of the
massive galaxy cluster Abell 2142 by combining the Sunyaev Zel'dovich (SZ)
effect with the X-ray signal. Methods. We combined the SZ pressure profile
measured by Planck with the XMM-Newton gas density profile to recover radial
profiles of temperature, entropy and hydrostatic mass out to 2R500. We used a
method that is insensitive to clumping to recover the gas density, and we
compared the results with traditional X-ray measurement techniques. Results.
When taking clumping into account, our joint SZ/X-ray entropy profile is
consistent with the predictions from pure gravitational collapse, whereas a
significant entropy flattening is found when the effect of clumping is
neglected. The hydrostatic mass profile recovered using joint X-ray/SZ data
agrees with that obtained from spectroscopic X-ray measurements and with mass
reconstructions obtained through weak lensing and galaxy kinematics.
Conclusions. We found that clumping can explain the entropy flattening observed
by Suzaku in the outskirts of several clusters. When using a method insensitive
to clumping for the reconstruction of the gas density, the thermodynamic
properties of Abell 2142 are compatible with the assumption that the thermal
gas pressure sustains gravity and that the entropy is injected at accretion
shocks, with no need to evoke more exotic physics. Our results highlight the
need for X-ray observations with sufficient spatial resolution, and large
collecting area, to understand the processes at work in cluster outer regions.Comment: 22 pages, 32 figures, accepted in the journal A&
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