6,042 research outputs found
Ordinary and Extraordinary Hadrons
Resonances and enhancements in meson-meson scattering can be divided into two
classes distinguished by their behavior as the number of colors N_c in QCD
becomes large: The first are ordinary mesons that become stable as N_c goes to
infinity. This class includes textbook q-bar q mesons as well as glueballs and
hybrids. The second class, extraordinary mesons, are enhancements that
disappear as N_c goes to infinity; they subside into the hadronic continuum.
This class includes indistinct and controversial objects that have been
classified as q-bar q-bar q q mesons or meson-meson molecules. Pelaez's study
of the N_c dependence of unitarized chiral dynamics illustrates both classes:
the p-wave pi-pi and K-pi resonances, the rho(770) and K*(892), behave as
ordinary mesons; the s-wave pi-pi and K-pi enhancements, the sigma(600) and
kappa(800), behave like extraordinary mesons. Ordinary mesons resemble Feshbach
resonances while extraordinary mesons look more like effects due to potentials
in meson-meson scattering channels. I build and explore toy models along these
lines. Finally I discuss some related dynamical issues affecting the
interpretation of extraordinary mesons.Comment: 18 pages, 10 figures, talk presented at the 2006 Yukawa International
Seminar: New Frontiers in QCD, Kyoto University, November 2006. This talk is
dedicated to the memory of R. H. Dalit
R&D results on a CsI-TTGEM based photodetector
The very high momentum particle identification detector proposed for the
ALICE upgrade is a focusing RICH using a C4F10 gaseous radiator. For the
detection of Cherenkov photons, one of the options currently under
investigation is to use a CsI coated Triple-Thick-GEM (CsI-TTGEM) with metallic
or resistive electrodes. We will present results from the laboratory studies as
well as preliminary results of beam tests of a RICH detector prototype
consisting of a CaF2 radiator coupled to a 10x10 cm2 CsI-TTGEM equipped with a
pad readout and GASSIPLEX-based front-end electronics. With such a prototype
the detection of Cherenkov photons simultaneously with minimum ionizing
particles has been achieved for the first time in a stable operation mode
Lâambiente marino costiero: aspetti e tutela. Progetto formativo di Alternanza Scuola Lavoro 2016â2019 Liceo Scienze Applicate
Il percorso formativo consente di acquisire nozioni teoriche e pratiche sulle moderne tecniche (strumentali e metodologiche) di investigazione del âdatumâ geologico finalizzate allo studio multidisciplinare dellâambiente marinoâcostiero, con particolare riguardo alle ricerche sperimentali che lâIstituto IAMC ha condotto e conduce nel Golfo di Napoli.
Vengono trattate anche tematiche di gestione del sistema sicurezza e qualità con particolare riguardo alle attività lavorative di ricerca (acquisizione, elaborazione e restituzione del dato),nonché indicazioni di procedure gestionali di progetto finalizzate al corretto utilizzo della risorsa umana e strumentale
Umbilical Cord Knots: Is the Number Related to Fetal Risk?
True knots of the umbilical cord (UC) are a rare occurrence and are reported in 0.4â1.2% of deliveries. The compression of true knot of the UC can cause obstruction of the fetal circulation, leading to intraâuterine growth retardation or fetal death. Predisposing factors for the genesis of the true UC knot are numerous and include all the conditions, which lead to a relatively large uterine volume. This situation may predispose to free and excessive fetal movements. Although not all true knots lead to perinatal complications, they have been associated with adverse pregnancy outcomes, including fetal distress, fetal hypoxia, intraâuterine growth restriction (IUGR), longâterm neurological damage, caesarean delivery and stillbirth. We present a rare case of operative delivery with vacuum in a multiparous woman at term of pregnancy with a double true knot of the UC. As in most cases, the diagnosis was made after delivery, as there were no fetal symptoms during pregnancy. Some authors assume that 3D power sonography may be useful in the diagnosis of true UC knots. However, 3D power Doppler cannot be considered as a definitive method. There are no specific prenatal indications to induce the physician to look for ultrasound signs suggestive of umbilical true knot. Some studies argue that cases of fetal death and fetal risk are directly related to the number of knots. We also support this thesis, even if further observational and retrospective studies are needed to demonstrate it
Upsilon Decay to a Pair of Bottom Squarks
We calculate the rate for decay into a pair of bottom squarks as a
function of the masses of the bottom squark and the gluino. Data from decays of
the states could provide significant new bounds on the existence and
masses of these supersymmetric particles.Comment: 10 pages, latex, 2 figure
A new family of symmetric integrable sigma models
(Minor corrections and reference added)Comment: (ITP Budapest Report No. 502) (11 page
Instability of two-dimensional heterotic stringy black holes
We solve the eigenvalue problem of general relativity for the case of charged
black holes in two-dimensional heterotic string theory, derived by McGuigan et
al. For the case of , we find a physically acceptable
time-dependent growing mode; thus the black hole is unstable. The extremal case
is stable.Comment: 11 pages, LaTe
Almotriptan in the treatment of migraine
Almotriptan is an orally administered, highly selective serotonin 5-HT(1B/1D) receptor agonist that is effective in the acute treatment of moderate to severe migraine attacks. Since its introduction on to the market in 2001, several studies involving a large number of migraine patients have confirmed its efficacy and tolerability profile. Almotriptan, was found to be among the best-responding triptans in terms of pain relief and pain-free rate at 2 h. It has been reported that almotriptan has the best sustained pain-free (SPF) rate and the lowest adverse events (AEs) rate of all the triptans. When these clinical characteristics were combined to form the composite endpoint SPF and no AEs (SNAE), almotriptan emerged as the triptan with the best efficacy and tolerability profile. It also showed a good efficacy profile during the early treatment (within 1 h of onset) of migraine attacks characterized by moderate pain intensity. On the basis of these findings, almotriptan may be considered a therapeutic option for the acute treatment of migraine attacks
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