5,964 research outputs found
Photo-desorption of H2O:CO:NH3 circumstellar ice analogs: Gas-phase enrichment
We study the photo-desorption occurring in HO:CO:NH ice mixtures
irradiated with monochromatic (550 and 900 eV) and broad band (250--1250 eV)
soft X-rays generated at the National Synchrotron Radiation Research Center
(Hsinchu, Taiwan). We detect many masses photo-desorbing, from atomic hydrogen
(m/z = 1) to complex species with m/z = 69 (e.g., CHNO, CHO,
CHN), supporting the enrichment of the gas phase.
At low number of absorbed photons, substrate-mediated exciton-promoted
desorption dominates the photo-desorption yield inducing the release of weakly
bound (to the surface of the ice) species; as the number of weakly bound
species declines, the photo-desorption yield decrease about one order of
magnitude, until porosity effects, reducing the surface/volume ratio, produce a
further drop of the yield.
We derive an upper limit to the CO photo-desorption yield, that in our
experiments varies from 1.4 to 0.007 molecule photon in the range ~absorbed photons cm. We apply these findings to a
protoplanetary disk model irradiated by a central T~Tauri star
Stable Determination of the Electromagnetic Coefficients by Boundary Measurements
The goal of this paper is to prove a stable determination of the coefficients
for the time-harmonic Maxwell equations, in a Lipschitz domain, by boundary
measurements
Phasing diffuse scattering. Application of the SIR2002 algorithm to the non-crystallographic phase problem
A new phasing algorithm has been used to determine the phases of diffuse
elastic X-ray scattering from a non-periodic array of gold balls of 50 nm
diameter. Two-dimensional real-space images, showing the charge-density
distribution of the balls, have been reconstructed at 50 nm resolution from
transmission diffraction patterns recorded at 550 eV energy. The reconstructed
image fits well with scanning electron microscope (SEM) image of the same
sample. The algorithm, which uses only the density modification portion of the
SIR2002 program, is compared with the results obtained via the
Gerchberg-Saxton-Fienup HIO algorithm. In this way the relationship between
density modification in crystallography and the HiO algorithm used in signal
and image processing is elucidated.Comment: 7 pages, 12 figure
Expression of the endocannabinoid receptors in human fascial tissue.
open7noCannabinoid receptors have been localized in the central and peripheral nervous system as well as on cells of the immune system, but recent studies on animal tissue gave evidence for the presence of cannabinoid receptors in different types of tissues. Their presence was supposed also in myofascial tissue, suggesting that the endocannabinoid system may help resolve myofascial trigger points and relieve symptoms of fibromyalgia. However, until now the expression of CBI (cannabinoid receptor I) and CB2 (cannabinoid receptor 2) in fasciae has not yet been established. Small samples of fascia were collected from volunteers patients during orthopedic surgery. For each sample were done a cell isolation, immunohistochemical investigation (CB1 and CB2 antibodies) and real time RT-PCR to detect the expression of CB1 and CB2. Both cannabinoid receptors are expressed in human fascia and in human fascial fibroblasts culture cells. although to a lesser extent than the control gene. We can assume that the expression of mRNA and protein of CBI and CB2 receptors in fascial tissue are concentrated into the fibroblasts This is the first demonstration that the fibroblasts of the muscular fasciae express CBI and CB2. The presence of these receptors could help to provide a description of cannabinoid receptors distribution and to better explain the role of fasciae as pain generator and the efficacy of some fascial treatments. Indeed the endocannabinoid receptors of fascial fibroblasts can contribute to modulate the fascial fibrosis and inflammation.noneopenFede, C; Albertin, G; Petrelli, L; Sfriso, Mm; Biz, C; De Caro, R; Stecco, CFede, C; Albertin, Giovanna; Petrelli, Lucia; Sfriso, MARIA MARTINA; Biz, Carlo; DE CARO, Raffaele; Stecco, Carl
Tropical Dominating Sets in Vertex-Coloured Graphs
Given a vertex-coloured graph, a dominating set is said to be tropical if
every colour of the graph appears at least once in the set. Here, we study
minimum tropical dominating sets from structural and algorithmic points of
view. First, we prove that the tropical dominating set problem is NP-complete
even when restricted to a simple path. Then, we establish upper bounds related
to various parameters of the graph such as minimum degree and number of edges.
We also give upper bounds for random graphs. Last, we give approximability and
inapproximability results for general and restricted classes of graphs, and
establish a FPT algorithm for interval graphs.Comment: 19 pages, 4 figure
On the evaluation of some three-body variational integrals
Stable recursive relations are presented for the numerical computation of the
integrals
(, and integer, , and real) when the
indices , or are negative. Useful formulas are given for particular
values of the parameters , and .Comment: 12 pages, 1 figure (PS) and 3 tables. Old figures 2 and 3 replaced by
Tables I and III. A further table added. Paper enlarged giving some tips on
the convergence of quadrature
- …