Spin Density Matrix Elements (SDMEs) describing the angular distribution of exclusive
ρ
0
electroproduction and decay are determined in the HERMES experiment with 27.6 GeV beam energy and unpolarized ...hydrogen and deuterium targets. Eight (fifteen) SDMEs that are related (unrelated) to the longitudinal polarization of the beam are extracted in the kinematic region 1<
Q
2
<7 GeV
2
, 3.0<
W
<6.3 GeV, and −
t
<0.4 GeV
2
. Within the given experimental uncertainties, a hierarchy of relative sizes of helicity amplitudes is observed. Kinematic dependences of all SDMEs on
Q
2
and
t
are presented, as well as the longitudinal-to-transverse
ρ
0
electroproduction cross-section ratio as a function of
Q
2
. A small but statistically significant deviation from the hypothesis of
s
-channel helicity conservation is observed. An indication is seen of a contribution of unnatural-parity-exchange amplitudes; these amplitudes are naturally generated with a quark-exchange mechanism.
Corticotropin-releasing factor (CRF), the major regulator of the stress response within the central nervous system, is also present at peripheral sites, including the gonads, and the gene encoding ...its own receptor can be finely induced in selective ovarian compartments in both control and stressful conditions during the gonadal life cycle. The present study, therefore, investigated the influence of both gonadal function and estrous cycle on the immunoreactive CRF (irCRF) contents in the immature and adult rat ovary. In addition, the effect of an acute (5 min) or chronic intermittent (twice a day for 4 days) cold swimming stress on ovarian irCRF contents was evaluated. High-performance liquid chromatography (HPLC), gel-chromatography (Sephadex G-75, 45 x 1 cm) and a direct radioimmunoassay were performed to measure irCRF ovarian contents. The HPLC elution profile of irCRF in ovarian tissues of adult rats was superimposable on that of synthetic rat/human CRF and gel-chromatograms performed according to the phase of the estrous cycle revealed higher irCRF contents at proestrus. Total irCRF ovarian content was undetectable both in control and acute stressed immature rats, while adult rats showed the highest values at proestrus (p < 0.0001). The acute stress exposure induced a significant increase (p < 0.0001) of irCRF ovarian contents only at proestrus, without affecting irCRF at the other phases of the estrous cycle. Finally, no significant changes were found in ovarian irCRF after chronic intermittent stress. The proestrus-related changes of ovarian irCRF, confirming the adult ovary as an extrahypothalamic source of CRF, may constitute a neuropeptidergic signal involved in the gonadal reproductive cycle. Furthermore, the stress-related changes of ovarian irCRF indicated that the gonad may be locally sensitive to acute stressful stimuli.
An experiment measuring electroproduction of hypernuclei has been performed in hall A at Jefferson Lab on a 12C target. In order to increase counting rates and provide unambiguous kaon identification ...two superconducting septum magnets and a ring imaging Cherenkov detector were added to the hall A standard equipment. An unprecedented energy resolution of less than 700 keV FWHM has been achieved. Thus, the observed (Lambda)(12)B spectrum shows for the first time identifiable strength in the core-excited region between the ground-state s-wave Lambda peak and the 11 MeV p-wave Lambda peak.
We have developed and testes several new designs of GEM detectors with micropattern electrodes manufactured by microelectronic technology. In one designs the inner layer of the detector's electrode ...consists of thin metallic strips and the outer layer is made of a resistive grid manufactured by a screen printing technology. In other designs, the electrodes were made of metallic strips fed by HV via micro-resistors manufactured by a screen printing technology. Due to these features, the new detectors have several important advantages over conventional GEMs or ordinary thick GEMs. For example, the resistive grid (in the first design) and the screen printed resistors (in other designs) limited the current in case of discharges which make the detectors intrinsically spark-protected. We will here describe our tests with the photosensitive versions of these detectors (coated with CsI layers) and the efforts of implementing them in several applications. In particular, we will focus on our activity towards the ALICE RICH detector upgrade and on tests of simplified prototypes of cryogenic dark matter detectors.
Hard exclusive electroproduction of π+π− pairs off hydrogen and deuterium targets has been studied by the HERMES experiment at DESY. Legendre moments 〈P1〉 and 〈P3〉 of the angular distributions of π+ ...mesons in the center-of-mass frame of the pair have been measured for the first time. Their dependence on the π+π− invariant mass can be understood as being due to the interference between relative P-wave (isovector) and S-, D-wave (isoscalar) states of the two pions. The increase in magnitude of 〈P1〉 as Bjorken x increases is interpreted in the framework of generalized parton distributions as an enhancement of flavour non-singlet qq¯ exchange for larger values of x, which leads to a sizable admixture of isoscalar and isovector pion pairs. In addition, the interference between P-wave and D-wave states separately for transverse and longitudinal pion pairs has been studied. The data indicate that in the f2(1270) region at 〈Q2〉=3 GeV2 higher-twist effects can be as large as the leading-twist longitudinal component.
Headache is one of the most common types of pain and, in the absence of biological markers, headache diagnosis depends only on information obtained from clinical interviews and physical and ...neurological examinations. Headache diaries make it possible to record prospectively the characteristics of every attack and the use of headache calendars is indicated for evaluating the time pattern of headache, identifying aggravating factors and evaluating the efficacy of preventive treatment. This may reduce the recall bias and increase accuracy in the description. The use of diagnostic headache diaries does have some limitations because the patient's general acceptance is still limited and some subjects are not able to fill in a diary. In this review, we considered diaries and calendars especially designed for migraine and, in particular, we aimed at: (i) determining what instruments are available in clinical practice for diagnosis and follow-up of treatments; and (ii) describing the tools that have been developed for research and their main applications in the headache field. In addition to the literature review, we added two paragraphs concerning the authors' experience of the use of diaries and calendars in headache centres and their proposals for future areas of research
The transverse momentum and rapidity distributions of net protons and negatively charged hadrons have been measured for minimum bias proton–nucleus and deuteron–gold interactions, as well as central ...oxygen–gold and sulphur–nucleus collisions at 200 GeV per nucleon. The rapidity density of net protons at midrapidity in central nucleus–nucleus collisions increases both with target mass for sulphur projectiles and with the projectile mass for a gold target. The shape of the rapidity distributions of net protons forward of midrapidity for d+Au and central S+Au collisions is similar. The average rapidity loss is larger than 2 units of rapidity for reactions with the gold target. The transverse momentum spectra of net protons for all reactions can be described by a thermal distribution with ‘temperatures’ between 145 ± 11 MeV (p+S interactions) and 244 ± 43 MeV (central S+Au collisions). The multiplicity of negatively charged hadrons increases with the mass of the colliding system. The shape of the transverse momentum spectra of negatively charged hadrons changes from minimum bias p+p and p+S interactions to p+Au and central nucleus-nucleus collisions. The mean transverse momentum is almost constant in the vicinity of midrapidity and shows little variation with the target and projectile masses. The average number of produced negatively charged hadrons per participant baryon increases slightly from p+p, p+A to central S+S,Ag collisions.
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