Proton-Capture Rates on Carbon Isotopes and Their Impact on the Astrophysical

The ^{12}C/^{13}C ratio is a significant indicator of nucleosynthesis and mixing processes during hydrogen burning in stars. Its value mainly depends on the relative rates of the ^{12}C(p,γ)^{13}N and ^{13}C(p,γ)^{14}N reactions. Both reactions have been studied at the Laboratory for Underground Nuclear Astrophysics (LUNA) in Italy down to the lowest energies to date (E_{c.m.}=60 keV) reaching for the first time the high energy tail of hydrogen burning in the shell of giant stars. Our cross sections, obtained with both prompt γ-ray detection and activation measurements, are the most precise to date with overall systematic uncertainties of 7%-8%. Compared with most of the literature, our results are systematically lower, by 25% for the ^{12}C(p,γ)^{13}N reaction and by 30% for ^{13}C(p,γ)^{14}N. We provide the most precise value up to now of 3.6±0.4 in the 20-140 MK range for the lowest possible ^{12}C/^{13}C ratio that can be produced during H burning in giant stars.

Direct Measurement of the

One of the main neutron sources for the astrophysical s process is the reaction ^{13}C(α,n)^{16}O, taking place in thermally pulsing asymptotic giant branch stars at temperatures around 90 MK. To model the nucleosynthesis during this process the reaction cross section needs to be known in the 150-230 keV energy window (Gamow peak). At these sub-Coulomb energies, cross section direct measurements are severely affected by the low event rate, making us rely on input from indirect methods and extrapolations from higher-energy direct data. This leads to an uncertainty in the cross section at the relevant energies too high to reliably constrain the nuclear physics input to s-process calculations. We present the results from a new deep-underground measurement of ^{13}C(α,n)^{16}O, covering the energy range 230-300 keV, with drastically reduced uncertainties over previous measurements and for the first time providing data directly inside the s-process Gamow peak. Selected stellar models have been computed to estimate the impact of our revised reaction rate. For stars of nearly solar composition, we find sizeable variations of some isotopes, whose production is influenced by the activation of close-by branching points that are sensitive to the neutron density, in particular, the two radioactive nuclei ^{60}Fe and ^{205}Pb, as well as ^{152}Gd.

The baryon density of the Universe from an improved rate of deuterium burning.

Light elements were produced in the first few minutes of the Universe through a sequence of nuclear reactions known as Big Bang nucleosynthesis (BBN)1,2. Among the light elements produced during BBN1,2, deuterium is an excellent indicator of cosmological parameters because its abundance is highly sensitive to the primordial baryon density and also depends on the number of neutrino species permeating the early Universe. Although astronomical observations of primordial deuterium abundance have reached percent accuracy3, theoretical predictions4-6 based on BBN are hampered by large uncertainties on the cross-section of the deuterium burning D(p,γ)3He reaction. Here we show that our improved cross-sections of this reaction lead to BBN estimates of the baryon density at the 1.6 percent level, in excellent agreement with a recent analysis of the cosmic microwave background7. Improved cross-section data were obtained by exploiting the negligible cosmic-ray background deep underground at the Laboratory for Underground Nuclear Astrophysics (LUNA) of the Laboratori Nazionali del Gran Sasso (Italy)8,9. We bombarded a high-purity deuterium gas target10 with an intense proton beam from the LUNA 400-kilovolt accelerator11 and detected the γ-rays from the nuclear reaction under study with a high-purity germanium detector. Our experimental results settle the most uncertain nuclear physics input to BBN calculations and substantially improve the reliability of using primordial abundances to probe the physics of the early Universe.

Direct Capture Cross Section and the E_{p}=71 and 105 keV Resonances in the

The ^{22}Ne(p,γ)^{23}Na reaction, part of the neon-sodium cycle of hydrogen burning, may explain the observed anticorrelation between sodium and oxygen abundances in globular cluster stars. Its rate is controlled by a number of low-energy resonances and a slowly varying nonresonant component. Three new resonances at E_{p}=156.2, 189.5, and 259.7 keV have recently been observed and confirmed. However, significant uncertainty on the reaction rate remains due to the nonresonant process and to two suggested resonances at E_{p}=71 and 105 keV. Here, new ^{22}Ne(p,γ)^{23}Na data with high statistics and low background are reported. Stringent upper limits of 6×10^{-11} and 7×10^{-11} eV (90% confidence level), respectively, are placed on the two suggested resonances. In addition, the off-resonant S factor has been measured at unprecedented low energy, constraining the contributions from a subthreshold resonance and the direct capture process. As a result, at a temperature of 0.1 GK the error bar of the ^{22}Ne(p,γ)^{23}Na rate is now reduced by 3 orders of magnitude.

Erratum: Three New Low-Energy Resonances in the

This corrects the article DOI: 10.1103/PhysRevLett.115.252501.

Improved Direct Measurement of the 64.5 keV Resonance Strength in the

The ^{17}O(p,α)^{14}N reaction plays a key role in various astrophysical scenarios, from asymptotic giant branch stars to classical novae. It affects the synthesis of rare isotopes such as ^{17}O and ^{18}F, which can provide constraints on astrophysical models. A new direct determination of the E_{R}=64.5 keV resonance strength performed at the Laboratory for Underground Nuclear Astrophysics (LUNA) accelerator has led to the most accurate value to date ωγ=10.0±1.4_{stat}±0.7_{syst} neV, thanks to a significant background reduction underground and generally improved experimental conditions. The (bare) proton partial width of the corresponding state at E_{x}=5672 keV in ^{18}F is Γ_{p}=35±5_{stat}±3_{syst} neV. This width is about a factor of 2 higher than previously estimated, thus leading to a factor of 2 increase in the ^{17}O(p, α)^{14}N reaction rate at astrophysical temperatures relevant to shell hydrogen burning in red giant and asymptotic giant branch stars. The new rate implies lower ^{17}O/^{16}O ratios, with important implications on the interpretation of astrophysical observables from these stars.

Three New Low-Energy Resonances in the

The ^{22}Ne(p,γ)^{23}Na reaction takes part in the neon-sodium cycle of hydrogen burning. This cycle affects the synthesis of the elements between ^{20}Ne and ^{27}Al in asymptotic giant branch stars and novae. The ^{22}Ne(p,γ)^{23}Na reaction rate is very uncertain because of a large number of unobserved resonances lying in the Gamow window. At proton energies below 400 keV, only upper limits exist in the literature for the resonance strengths. Previous reaction rate evaluations differ by large factors. In the present work, the first direct observations of the ^{22}Ne(p,γ)^{23}Na resonances at 156.2, 189.5, and 259.7 keV are reported. Their resonance strengths are derived with 2%-7% uncertainty. In addition, upper limits for three other resonances are greatly reduced. Data are taken using a windowless ^{22}Ne gas target and high-purity germanium detectors at the Laboratory for Underground Nuclear Astrophysics in the Gran Sasso laboratory of the National Institute for Nuclear Physics, Italy, taking advantage of the ultralow background observed deep underground. The new reaction rate is a factor of 20 higher than the recent evaluation at a temperature of 0.1 GK, relevant to nucleosynthesis in asymptotic giant branch stars.

Oral tuberculosis: a tongue case report.

The authors report a case of oral tuberculosis in a 38-year-old heavy cigarette smoker man. He showed a painful, non-healing ulcer with indurated borders of the lateral surface of the tongue. No tonsil or lymph node enlargement was also noted. The medical history was not significant for systemic disease. Histopathological examination showed granulomas exhibiting a central caseinating necrotic focus, surrounded by mononuclear cells, epithelioid histiocytes and multi nucleated Langhans giant cells. A mantle of lympocytes and fibrous tissue surrounded the granulomas. Since the morphologic picture oriented for tubercoloid granulomata, a Ziehl-Neelsen staining of the tissue was performed. Chest radiography did not detect any pulmonary or nodal disease. On the bases of these results a diagnosis of oral tuberculosis was established.

First direct measurement of the 17O(p,γ)18F reaction cross section at Gamow energies for classical novae.

Classical novae are important contributors to the abundances of key isotopes, such as the radioactive (18)F, whose observation by satellite missions could provide constraints on nucleosynthesis models in novae. The (17)O(p,γ)(18)F reaction plays a critical role in the synthesis of both oxygen and fluorine isotopes, but its reaction rate is not well determined because of the lack of experimental data at energies relevant to novae explosions. In this study, the reaction cross section has been measured directly for the first time in a wide energy range E(c.m.)~/= 200-370 keV appropriate to hydrogen burning in classical novae. In addition, the E(c.m.)=183 keV resonance strength, ωγ=1.67±0.12 µeV, has been measured with the highest precision to date. The uncertainty on the (17)O(p,γ)(18)F reaction rate has been reduced by a factor of 4, thus leading to firmer constraints on accurate models of novae nucleosynthesis.

Stellar and primordial nucleosynthesis of 7Be: measurement of 3He(alpha,gamma)7Be.

The 3He(alpha,gamma)7Be reaction presently represents the largest nuclear uncertainty in the predicted solar neutrino flux and has important implications on the big bang nucleosynthesis, i.e., the production of primordial 7Li. We present here the results of an experiment using the recoil separator ERNA (European Recoil separator for Nuclear Astrophysics) to detect directly the 7Be ejectiles. In addition, off-beam activation and coincidence gamma-ray measurements were performed at selected energies. At energies above 1 MeV a large discrepancy compared to previous results is observed both in the absolute value and in the energy dependence of the cross section. Based on the available data and models, a robust estimate of the cross section at the astrophysical relevant energies is proposed.

The treatment of NAFLD.

Nonalcoholic fatty liver disease (NAFLD) is becoming an increasing cause of chronic liver damage. The decision of start a medical treatment is based on the documented risk of progression to cirrhosis and liver cancer, when steatohepatitis (NASH) occurs. The therapy of this syndrome requires, as obviously, some considerations on the natural history of the condition, on the efficacy and safety of various therapeutic options, as well as on the costs. Treatment of patients with NAFLD has typically been focused on the management of associated conditions such as obesity, diabetes mellitus and hyperlipemia. Weight loss improves insulin sensitivity, and NASH may resolve with weight reduction. Insulin resistance seems to be the common denominator in many cases of NAFLD. Two classes of drugs have been shown to correct insulin resistance: biguanides (e.g., metformin) and thiazolidinediones (e.g., rosiglitazone and pioglitazone). The last two decades have witnessed a considerable progress in the understanding of the mechanisms respon-sible for the fibrogenic progression of chronic liver diseases. Several drugs believed to be hepatoprotective or antifibrotic agent as UDCA, betaine, vitamin E, lecithin, beta-carotene and selenium have been used in patients with NASH. Silybin is the main component of silymarin that is absorbed when linked whith a phytosome. This substance reduces in rats the lipid-peroxidation and the activaction of hepatic stellate cells. In humans, some non controlled data show that silybin is able to reduce insulin resistance, liver steatosis and plasma markers of liver fibrosis.

[Effects of a new pharmacological complex (silybin + vitamin-E + phospholipids) on some markers of the metabolic syndrome and of liver fibrosis in patients with hepatic steatosis. Preliminary study]. / Effeto di un nuovo complesso farmacologico (sillibina vitamina E+ fosfolipidi) su alcuni indicatori di sindrome metabolica e di fibrosi epatica in pazienti con epatopatia steatosica. Studio pilota.

AIM: This open preliminary pilot study was aimed to evaluate the effect of a new pharmaceutical complex (silybin+vitamin E+phospholipids - RealSIL-IBI-Lorenzini Pharmaceutical, Italy) on some parameters of metabolic syndrome and of liver fibrosis in patients with non alcoholic fatty liver disease (NAFLD) with or without the contemporaneous presence of hepatitis C virus (HCV)-related chronic hepatitis. METHODS: Eighty five patients were consecutively enrolled in the study and divided in 2 groups; the first group was represented by 59 patients affected by NAFLD, negative for other known causes of chronic liver damage (M/F= 39/20; median age and range: 44 years, 22-76, group A); the second group was represented by 26 patients (M/F=19/7; median age and range 51 years, 20-75, group B) with HCV-related chronic hepatitis associated to NAFLD. Adverse events and drop-outs were absent in all group and compliance at the study was absolute. RESULTS: This open preliminary study shows that the new compound silybin+vitamin E+ phospholipids is active, in vivo, and produces some therapeutic effects in patients with different forms of chronic liver damage. In particular, it improves insulin resistance and plasma levels of markers of liver fibrosis in patients in whom these parameters are particularly altered. CONCLUSIONS: Our data have a role of suggestion to further evaluate, through a controlled trial, a possible therapeutic use of this new compound in the management of patients with NAFLD.

Process and data nets: the conceptual model of the M*-OBJECT methodology.

The paper describes a specification model, called the Process and Data Net (PDN) model, used as the modeling tool for the M*-OBJECT information system design methodology. The model integrates the representation of static, dynamic, and behavioral aspects of a database application. PDN consists of two components: an object-oriented data model that describes static and behavioral aspects of objects of the system under analysis, and a process model that specifies a way organization activities must be coordinated. The major features of the proposed approach are: 1) the system representation captures all relevant properties from the end-user viewpoint without unnecessary details concerning implementation, 2) complex data structures and data manipulations can be specified, and 3) specifications are executable for rapid prototyping.