290 research outputs found
Effective Rheology of Bubbles Moving in a Capillary Tube
We calculate the average volumetric flux versus pressure drop of bubbles
moving in a single capillary tube with varying diameter, finding a square-root
relation from mapping the flow equations onto that of a driven overdamped
pendulum. The calculation is based on a derivation of the equation of motion of
a bubble train from considering the capillary forces and the entropy production
associated with the viscous flow. We also calculate the configurational
probability of the positions of the bubbles.Comment: 4 pages, 1 figur
Ghrelin Modulates the fMRI BOLD Response of Homeostatic and Hedonic Brain Centers Regulating Energy Balance in the Rat
The orexigenic gut-brain peptide, ghrelin and its G-protein coupled receptor, the growth hormone secretagogue receptor
1a (GHS-R1A) are pivotal regulators of hypothalamic feeding centers and reward processing neuronal circuits of the brain.
These systems operate in a cooperative manner and receive a wide array of neuronal hormone/transmitter messages and
metabolic signals. Functional magnetic resonance imaging was employed in the current study to map BOLD responses to
ghrelin in different brain regions with special reference on homeostatic and hedonic regulatory centers of energy balance.
Experimental groups involved male, ovariectomized female and ovariectomized estradiol-replaced rats. Putative modulation
of ghrelin signaling by endocannabinoids was also studied. Ghrelin-evoked effects were calculated as mean of the BOLD
responses 30 minutes after administration. In the male rat, ghrelin evoked a slowly decreasing BOLD response in all studied
regions of interest (ROI) within the limbic system. This effect was antagonized by pretreatment with GHS-R1A antagonist
JMV2959. The comparison of ghrelin effects in the presence or absence of JMV2959 in individual ROIs revealed significant
changes in the prefrontal cortex, nucleus accumbens of the telencephalon, and also within hypothalamic centers like the
lateral hypothalamus, ventromedial nucleus, paraventricular nucleus and suprachiasmatic nucleus. In the female rat, the
ghrelin effects were almost identical to those observed in males. Ovariectomy and chronic estradiol replacement had no
effect on the BOLD response. Inhibition of the endocannabinoid signaling by rimonabant significantly attenuated the
response of the nucleus accumbens and septum. In summary, ghrelin can modulate hypothalamic and mesolimbic
structures controlling energy balance in both sexes. The endocannabinoid signaling system contributes to the
manifestation of ghrelinâs BOLD effect in a region specific manner. In females, the estradiol milieu does not influence the
BOLD response to ghrelin
Studies on Cercariae from Kuwait Bay. XI. Description and surface topography of Cercaria kuwaitae XI sp.n. (Digenea: Echinostomatidae)
Epidemiology of Invasive Fungal Infections in Latin America
The pathogenic role of invasive fungal infections (IFIs) has increased during the past two decades in Latin America and worldwide, and the number of patients at risk has risen dramatically. Working habits and leisure activities have also been a focus of attention by public health officials, as endemic mycoses have provoked a number of outbreaks. An extensive search of medical literature from Latin America suggests that the incidence of IFIs from both endemic and opportunistic fungi has increased. The increase in endemic mycoses is probably related to population changes (migration, tourism, and increased population growth), whereas the increase in opportunistic mycoses may be associated with the greater number of people at risk. In both cases, the early and appropriate use of diagnostic procedures has improved diagnosis and outcome
Alignment of the ALICE Inner Tracking System with cosmic-ray tracks
37 pages, 15 figures, revised version, accepted by JINSTALICE (A Large Ion Collider Experiment) is the LHC (Large Hadron Collider) experiment devoted to investigating the strongly interacting matter created in nucleus-nucleus collisions at the LHC energies. The ALICE ITS, Inner Tracking System, consists of six cylindrical layers of silicon detectors with three different technologies; in the outward direction: two layers of pixel detectors, two layers each of drift, and strip detectors. The number of parameters to be determined in the spatial alignment of the 2198 sensor modules of the ITS is about 13,000. The target alignment precision is well below 10 micron in some cases (pixels). The sources of alignment information include survey measurements, and the reconstructed tracks from cosmic rays and from proton-proton collisions. The main track-based alignment method uses the Millepede global approach. An iterative local method was developed and used as well. We present the results obtained for the ITS alignment using about 10^5 charged tracks from cosmic rays that have been collected during summer 2008, with the ALICE solenoidal magnet switched off.Peer reviewe
First measurement of coherent Ï0 photoproduction in ultra-peripheral XeâXe collisions at âsNN = 5.44 TeV
The first measurement of the coherent photoproduction of Ï0 vector mesons in ultra-peripheral XeâXe collisions at sNN=5.44 TeV is presented. This result, together with previous HERA Îłp data and ÎłâPb measurements from ALICE, describes the atomic number (A) dependence of this process, which is particularly sensitive to nuclear shadowing effects and to the approach to the black-disc limit of QCD at a semi-hard scale. The cross section of the Xe+XeâÏ0+Xe+Xe process, measured at midrapidity through the decay channel Ï0âÏ+Ïâ, is found to be dÏ/dy=131.5±5.6(stat.)â16.9+17.5(syst.) mb. The ratio of the continuum to resonant contributions for the production of pion pairs is also measured. In addition, the fraction of events accompanied by electromagnetic dissociation of either one or both colliding nuclei is reported. The dependence on A of cross section for the coherent Ï0 photoproduction at a centre-of-mass energy per nucleon of the ÎłA system of WÎłA,n=65 GeV is found to be consistent with a power-law behaviour Ï(ÎłAâÏ0A)âAα with a slope α=0.96±0.02(syst.). This slope signals important shadowing effects, but it is still far from the behaviour expected in the black-disc limit.publishedVersio
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