88,773 research outputs found
Frazionamento isotopico δ13C e δ15N nel detrito vegetale vs colonizzazione fungina durante il processo di decomposizione in microcosmi di acqua dolce
No full texthttp://www.congresso.societaitalianaecologia.org/articles/andreoli-155.pd
Rising educational attainment and opportunity equalization: Evidence from France.
No full textEducational policies are widely recognized as the means par excellence to equalize opportunities among children with different social and family backgrounds and to promote intergenerational mobility. In this paper we focus on the French case and we apply the opportunity equalization criterion proposed by Andreoli, Havnes and Lefranc (2019) for evaluating the effect of rising compulsory schooling requirements in secondary education. Our results show that such education expansion has a limited redistributive effects on students earnings distribution. Nonetheless, we provide evidence of opportunity equalization among groups of students dened by family background circumstances
A laser application to nuclear astrophysics
No full textIn the last decade, the availability in high-intensity laser beams capable of producing plasmas with ion energies large enough to induce nuclear reactions has opened new research paths in nuclear physics. We studied the reactions 3He(d, p)4He and d(d,n)3He at temperatures of few keV in a plasma, generated by the interaction of intense ultrafast laser pulses with molecular deuterium or deuterated-methane clusters mixed with 3He atoms. The yield of 14.7 MeV protons from the 3He(d, p)4He reaction was used to extract the astrophysical S factor. Results of the experiment performed at the Center for High Energy Density Science at The University of Texas at Austin will be presented. © 2014 AIP Publishing LLC
Polimorfismo, ruolo istituzionale e convergenza dei modelli di giustizia costituzionale “diffusi”. Una convergenza ordinamentale tra Stati Uniti d’America e Argentina
No full textPolimorfismo, ruolo istituzionale e convergenza dei modelli di giustizia costituzionale “diffusi”. Una convergenza ordinamentale tra Stati Uniti d’America e Argentin
Identificazione di ITX in vini e succhi di frutta per GC/MS e LC/MS/MS
No full textIl lavoro riporta le condizioni operative che gli Autori ritengono più adatte al controllo di qualità degli alimenti, ed in particolare di vino e succhi di frutta, confezionati in contenitori dai quali risulta possibile la migrazione di ITX (isopropylthioxanthone). Le condizioni operative proposte consentono l'identificazione di ITX anche a concentrazioni inferiori a 10 ppb
Acrylamide levels in cooked rice, tomato sauces and some fast food on the Italian market
No full textThis study reports the results of evaluation of acrylamide levels in some foods that are common on the Italian market. Three foods commonly found in the national diet (rice, tomato sauce and fast food), were examined with the gas chromatograph (GC)/mass spectrometer (MS) analytical method. Results show that rice differs from risotto with respect to acrylamide levels: values of less than 50 μg/kg, for boiled rice, increase to 113 μg/kg when various ingredients are added to produce risotto. Similar results were found for tomato sauce on the Italian market: acrylamide values were less than 50 μg/kg for simple tomato sauce, to 124 μg/kg when other ingredients such as olives and capers were added. Fast foods (e.g., fried potatoes) contained the highest observed acrylamide levels, probably from cooking methods and acrylamide-rich precursors. For two fried potatoes of the same type, very differentiated values resulted (136 and 294 μg/kg)
Development of an high resolution neutron spectroscopy system using a diamond detector and a remote digital acquisition methodology
No full textThe need of performing high resolution fast neutron spectroscopy in a very harsh environment like that of the Radial Neutron Camera (RNC) of ITER, requires to develop new detectors and methodologies. Diamond detectors have been proved to be excellent candidates but the electronics needs a substantial improvement. Because of the high radiation level and the temperatures expected near the detector positions in the RNC, the electronics must be placed several meters away. A novel Fast Charge Amplifier (FCA) was developed that, connected to a diamond detector using several tens of meters of low capacitance coaxial cable, is able to produce fast output signals suitable to be processed by digital electronics. These fast output signals allow to operate at high count rates avoiding pile-up problems. This novel amplifier connected to a digitizer is here tested in the neutron energy range from 5 to 20.5 MeV using the mono-energetic neutrons produced by the Van de Graaff (VdG) accelerator of the EC-JRC-IRMM and by the PTB cyclotron. From the measurements the experimental response functions of the diamond detector at different neutron energies were obtained. The shape of the response functions have been compared with that predicted with a routine which was implemented for the Monte Carlo code MCNPX with the scope to validate the calculations versus the experimental data. The goal is to develop a tool which allows to calculate the diamond detector response functions also in term of absolute efficiency. This methodology along with the ability to measure at high reaction rates and the insensitivity to radiation damage launches the system described in this paper as a promising method for neutron spectrometry in the RNC of ITER. ᄅ 2014 Elsevier B.V
Model-independent determination of the astrophysical S factor in laser-induced fusion plasmas
No full textIn this work, we present a new and general method for measuring the astrophysical S factor of nuclear reactions in laser-induced plasmas and we apply it to H2(d,n)He3. The experiment was performed with the Texas Petawatt Laser, which delivered 150-270 fs pulses of energy ranging from 90 to 180 J to D2 or CD4 molecular clusters (where D denotes 2H). After removing the background noise, we used the measured time-of-flight data of energetic deuterium ions to obtain their energy distribution. We derive the S factor using the measured energy distribution of the ions, the measured volume of the fusion plasma, and the measured fusion yields. This method is model independent in the sense that no assumption on the state of the system is required, but it requires an accurate measurement of the ion energy distribution, especially at high energies, and of the relevant fusion yields. In the H2(d,n)He3 and He3(d,p)He4 cases discussed here, it is very important to apply the background subtraction for the energetic ions and to measure the fusion yields with high precision. While the available data on both ion distribution and fusion yields allow us to determine with good precision the S factor in the d+d case (lower Gamow energies), for the d+He3 case the data are not precise enough to obtain the S factor using this method. Our results agree with other experiments within the experimental error, even though smaller values of the S factor were obtained. This might be due to the plasma environment differing from the beam target conditions in a conventional accelerator experiment. © 2016 American Physical Society
Measurement of the plasma astrophysical S factor for the He3(d,p)He4 reaction in exploding molecular clusters
No full textThe plasma astrophysical S factor for the He3(d,p)He4 fusion reaction was measured for the first time at temperatures of few keV, using the interaction of intense ultrafast laser pulses with molecular deuterium clusters mixed with He3 atoms. Different proportions of D2 and He3 or CD4 and He3 were mixed in the gas target in order to allow the measurement of the cross section for the He3(d,p)He4 reaction. The yield of 14.7 MeV protons from the He3(d,p)He4 reaction was measured in order to extract the astrophysical S factor at low energies. Our result is in agreement with other S factor parametrizations found in the literature. © 2013 American Physical Society
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