138 research outputs found
Scalar form factors and nuclear interactions
The scalar-isoscalar term in the two-pion exchange potential is
abnormally large and does not respect the hierarchy of effects predicted by
chiral perturbation theory. We argue that this anomaly is associated with
non-perturbative effects, which are also present in the scalar form
factor.Comment: Talk given at the 20EFB, Pisa, Italy, September 2007. 3 pages and 4
figure
The characteristics of the mechanoreceptors of the hip with arthrosis
Mechanoreceptors have been extensively studied in different joints and distinct signals that convey proprioceptive information to the cortex. Several clinical reports have established a link between the number of mechanoreceptors and a deficient proprioceptive system; however, little or no literature suggest concentration of mechanoreceptors might be affected by hip arthrosis. The purpose of this study is first to determine the existence of mechanoreceptors and free nerve endings in the hip joint and to distinguish between their conditions: those with arthrosis and without arthrosis. Samples of 45 male hips were analyzed: 30 taken from patients with arthrosis that were submitted to total arthroplasty and 15 taken from male cadavers without arthrosis. The patients' ages ranged from 38 to75 years (average 56.5) and the cadavers' ages ranged from 21 to 50 years (average 35.5). The capsule, labrum, and femoral head ligament tissues were obtained during the arthroplasty procedure from 30 patients with arthrosis and from 15 male cadavers. The tissue was cut into fragments of around 3 mm. Each fragment was then immediately stained with gold chloride 1% solution and divided into sections of 6 μm thickness. The Mann-Whitney test was used for two groups and the ANOVA, Friedman and Kruskal-Wallis tests for more than two groups. Results show the mechanoreceptors (Pacini, Ruffini and Golgi corpuscles) and free nerve endings are present in the capsule, femoral head ligament, and labrum of the hip joint. When all the densities of the nerve endings were examined with regard to those with arthrosis and those without arthrosis, the mechanoreceptors of cadavers without arthrosis were found to be more pronounced and an increase in free nerve endings could be observed (p = 0.0082). Further studies, especially electrophysiological studies, need to be carried out to clarify the functions of the mechanoreceptors in the joints
Final results of Borexino Phase-I on low energy solar neutrino spectroscopy
Borexino has been running since May 2007 at the LNGS with the primary goal of
detecting solar neutrinos. The detector, a large, unsegmented liquid
scintillator calorimeter characterized by unprecedented low levels of intrinsic
radioactivity, is optimized for the study of the lower energy part of the
spectrum. During the Phase-I (2007-2010) Borexino first detected and then
precisely measured the flux of the 7Be solar neutrinos, ruled out any
significant day-night asymmetry of their interaction rate, made the first
direct observation of the pep neutrinos, and set the tightest upper limit on
the flux of CNO neutrinos. In this paper we discuss the signal signature and
provide a comprehensive description of the backgrounds, quantify their event
rates, describe the methods for their identification, selection or subtraction,
and describe data analysis. Key features are an extensive in situ calibration
program using radioactive sources, the detailed modeling of the detector
response, the ability to define an innermost fiducial volume with extremely low
background via software cuts, and the excellent pulse-shape discrimination
capability of the scintillator that allows particle identification. We report a
measurement of the annual modulation of the 7 Be neutrino interaction rate. The
period, the amplitude, and the phase of the observed modulation are consistent
with the solar origin of these events, and the absence of their annual
modulation is rejected with higher than 99% C.L. The physics implications of
phase-I results in the context of the neutrino oscillation physics and solar
models are presented
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Spectroscopy of geo-neutrinos from 2056 days of Borexino data
We report an improved geo-neutrino measurement with Borexino from 2056 days
of data taking. The present exposure is
protonyr. Assuming a chondritic Th/U mass ratio of 3.9, we obtain geo-neutrino events. The null
observation of geo-neutrinos with Borexino alone has a probability of (5.9). A geo-neutrino signal from the mantle is
obtained at 98\% C.L. The radiogenic heat production for U and Th from the
present best-fit result is restricted to the range 23-36 TW, taking into
account the uncertainty on the distribution of heat producing elements inside
the Earth.Comment: 4 pages, 4 figure
Measurement of neutrino flux from the primary proton--proton fusion process in the Sun with Borexino detector
Neutrino produced in a chain of nuclear reactions in the Sun starting from
the fusion of two protons, for the first time has been detected in a real-time
detector in spectrometric mode. The unique properties of the Borexino detector
provided an oppurtunity to disentangle pp-neutrino spectrum from the background
components. A comparison of the total neutrino flux from the Sun with Solar
luminosity in photons provides a test of the stability of the Sun on the
10 years time scale, and sets a strong limit on the power production in
the unknown energy sources in the Sun of no more than 4\% of the total energy
production at 90\% C.L.Comment: 15 pages, 2 tables, 3 figure
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