The $^{238}$U to $^{235}$U fission cross section ratio has been determined at
n_TOF up to $\sim$1 GeV, with two different detection systems, in different
geometrical configurations. A total of four ...datasets have been collected and
compared. They are all consistent to each other within the relative systematic
uncertainty of 3-4%. The data collected at n_TOF have been suitably combined to
yield a unique fission cross section ratio as a function of the neutron energy.
The result confirms current evaluations up to 200 MeV. A good agreement is also
observed with theoretical calculations based on the INCL++/Gemini++ combination
up to the highest measured energy. The n_TOF results may help solving a
long-standing discrepancy between the two most important experimental dataset
available so far above 20 MeV, while extending the neutron energy range for the
first time up to $\sim$1 GeV.
The integral cross section of the \(^{12}\)C(\(n,p\))\(^{12}\)B reaction has been determined for the first time in the neutron energy range from threshold to several GeV at the n_TOF facility at ...CERN. The measurement relies on the activation technique, with the \(\beta\)-decay of \(^{12}\)B measured over a period of four half-lives within the same neutron bunch in which the reaction occurs. The results indicate that model predictions, used in a variety of applications, are mostly inadequate. The value of the integral cross section reported here can be used as a benchmark for verifying or tuning model calculations.
In the present study the effects of a short term intensive glycaemic control obtained with subcutaneous insulin therapy on lipids and apoprotein levels, platelet aggregation, platelet sensitivity to ...prostacyclin and platelet thromboxane production were investigated in 20 patients with type 2 diabetes and vascular disease. In 11 out of the 20 patients there was a significant improvement of glycaemic control (fructosamine reduction). Only with tight improvement of glycaemic control there was significant change in the concentration of ADP and collagen required to produce 50% of the maximum aggregation wave response, in the responsiveness of platelet to PGI2 and in the TxB2 synthesis. Lower Apo B levels were also shown in the tight control group suggesting that Apo B changes may have influenced platelet aggregation and thromboxane synthesis.
P. Zugec, N. Colonna, D. Bosnar et al., Nucl. Instrum. Methods A
760, 57 (2014) The neutron sensitivity of the C$_6$D$_6$ detector setup used at n_TOF for
capture measurements has been studied by ...means of detailed GEANT4 simulations.
A realistic software replica of the entire n_TOF experimental hall, including
the neutron beam line, sample, detector supports and the walls of the
experimental area has been implemented in the simulations. The simulations have
been analyzed in the same manner as experimental data, in particular by
applying the Pulse Height Weighting Technique. The simulations have been
validated against a measurement of the neutron background performed with a
$^\mathrm{nat}$C sample, showing an excellent agreement above 1 keV. At lower
energies, an additional component in the measured $^\mathrm{nat}$C yield has
been discovered, which prevents the use of $^\mathrm{nat}$C data for neutron
background estimates at neutron energies below a few hundred eV. The origin and
time structure of the neutron background have been derived from the
simulations. Examples of the neutron background for two different samples are
demonstrating the important role of accurate simulations of the neutron
background in capture cross section measurements.
The cross section of the \(^{62}\)Ni(\(n,\gamma\)) reaction was measured with the time-of-flight technique at the neutron time-of-flight facility n_TOF at CERN. Capture kernels of 42 resonances were ...analyzed up to 200~keV neutron energy and Maxwellian averaged cross sections (MACS) from \(kT=5-100\) keV were calculated. With a total uncertainty of 4.5%, the stellar cross section is in excellent agreement with the the KADoNiS compilation at \(kT=30\) keV, while being systematically lower up to a factor of 1.6 at higher stellar temperatures. The cross section of the \(^{63}\)Ni(\(n,\gamma\)) reaction was measured for the first time at n_TOF. We determined unresolved cross sections from 10 to 270 keV with a systematic uncertainty of 17%. These results provide fundamental constraints on \(s\)-process production of heavier species, especially the production of Cu in massive stars, which serve as the dominant source of Cu in the solar system.
We investigated the influence of apolipoprotein (apo) E-containing particles on LDL receptor binding of large, buoyant LDL subfractions (LDL I) from subjects with predominantly large (phenotype A) ...and small (phenotype B) LDL particles. Direct binding by human fibroblast LDL receptors was tested at 4 degrees C before and after removal of apoE-containing particles by immunoaffinity chromatography. The binding affinity of total LDL I in phenotype B was greater than that in phenotype A (Kd of 1.83+/-0.3 and 3.43+/-0.9 nmol/L, respectively, P<.05). LDL I from phenotype B subjects had a higher apoE to apoB molar ratio than did that from phenotype A (0.16+/-0.04 versus 0.06+/-0.02, P<.05). Nondenaturing gradient gel electrophoresis of apoE-containing LDL I isolated by immunoaffinity chromatography revealed a substantially larger peak particle diameter than in apoE-free LDL I, and comparison of LDL I composition before and after immunoaffinity chromatography suggested an increase in triglyceride content of apoE-containing particles. After removal of these particles, there was a greater than twofold reduction in LDL receptor affinity of phenotype B LDL (Kd of 1.83+/-0.3 to 3.76+/-0.6, P<.01), whereas in phenotype A no change was observed (Kd of 3.43+/-0.9 to 3.57+/-0.4, respectively). The receptor affinity of apoE-free LDL I from phenotype A and B subjects did not differ. These findings confirm that large, buoyant LDL particles from phenotype B subjects have a higher LDL receptor affinity than does LDL I from phenotype A subjects and suggest that this difference is due to an increased content of large, triglyceride-enriched, apoE-containing lipoproteins. It is possible that the accumulation of these particles reflects abnormalities in the metabolism of remnant lipoproteins that contribute to atherosclerosis risk in phenotype B subjects.
The \(^{58}\)Ni \((n,\gamma)\) cross section has been measured at the neutron time of flight facility n_TOF at CERN, in the energy range from 27 meV up to 400 keV. In total, 51 resonances have been ...analyzed up to 122 keV. Maxwellian averaged cross sections (MACS) have been calculated for stellar temperatures of kT\(=\)5-100 keV with uncertainties of less than 6%, showing fair agreement with recent experimental and evaluated data up to kT = 50 keV. The MACS extracted in the present work at 30 keV is 34.2\(\pm\)0.6\(_\mathrm{stat}\pm\)1.8\(_\mathrm{sys}\) mb, in agreement with latest results and evaluations, but 12% lower relative to the recent KADoNIS compilation of astrophysical cross sections. When included in models of the s-process nucleosynthesis in massive stars, this change results in a 60% increase of the abundance of \(^{58}\)Ni, with a negligible propagation on heavier isotopes. The reason is that, using both the old or the new MACS, 58Ni is efficiently depleted by neutron captures.
In the framework of research on IVth generation reactors and high intensity neutron sources a low-power prototype neutron amplifier was recently proposed by INFN. It is based on a low-energy, high ...current proton cyclotron, whose beam, impinging on a thick Beryllium converter, produces a fast neutron spectrum. The world database on the neutron yield from thick Beryllium target in the 70 MeV proton energy domain is rather scarce. The new measurement was performed at LNS, covering a wide angular range from 0 to 150 degrees and an almost complete neutron energy interval. In this contribution the preliminary data are discussed together with the proposed ADS facility.
A consortium of 20 university departments of geriatrics and gerontology conducted the Italian Multicentric Study on Centenarians (IMSC), in order to assess the socio-economic, clinical and biological ...conditions of the Italian centenarians. The investigation involved 382 subjects randomly selected from a total of 1162 centenarians (234 men and 928 women), recorded by a census carried out until 31 December, 1993. Their case history, clinical and socio-economic data were recorded on a computerized clinical case sheet. Blood samples for the purpose of the present investigations were drawn from 257 of them. A great proportion (79%) of these latter subjects displayed satisfactory general conditions in their laboratory parameters, 18.3% of them had fairly good clinical conditions even with slightly modified laboratory parameters. Only a low percentage (2.8%) had poor general conditions with a marked anemia, hyperazotemia and uric acid levels. Long duration diabetes was practically absent, and only 5.5% of our centenarians displayed hyperglycemia with a mean duration time of 9.3 years. The prevalence of subjects with hypercholesterolemia was 31.1%. Only 4.3% of centenarians was affected by mixed form of dyslipidemia (hypertriglyceridemia associated with hypercholesterolemia), confirming that elevated blood lipid contents jeopardize really long survival.
In this study 126 subjects (91 males and 35 females, range of age 43-65 years) were studied by coronary angiography. We considered positive for coronary atherosclerosis also patients showing mild or ...moderate stenosis (> or = 25%). In all subjects we have evaluated serum lipid and apoprotein A-I, B, C-II, C-III and E levels; therefore also cholesterol concentrations in all lipoprotein fractions, separated by sequential ultracentrifugation (VLDL d < 1.006, LDL d 1.006-1.063, HDL d > 1.063 g/ml) and apoprotein B in LDL have been measured. Subjects with coronary atherosclerosis have shown significantly higher levels of total cholesterol, LDL-cholesterol, total cholesterol/HDL-cholesterol and LDL-cholesterol/HDL-cholesterol ratios than controls. Therefore, a lower apo A-I/apo B ratio in males and a higher LDL-apo B levels in females has been found in subjects with coronary atherosclerosis in comparison with controls. The stepwise multiple analysis has demonstrated that LDL-cholesterol levels is the parameter that best correlates with the presence of coronary atherosclerosis. These data confirm the importance of the reduction of LDL-cholesterol levels in primary and secondary prevention of coronary heart disease.
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