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.

Epidemiología de la Onicomicosis Pedis en adultos hospitalizados en un servicio de medicina en un hospital de tercer nivel en Chile / Epidemiology of Onychomycosis pedisinhospitalized adults at the internal medicine ward of a high complexity hospital in Chile

La prevalencia global de la onicomicosis pedis es de 4,3%, y en hospitalizados puede llegar hasta 8,9%. Aun así, se propone que está ampliamente subdiagnosticada. Personas añosas con comorbilidades presentan mayor riesgo de onicomicosis pedis y de sus complicaciones. Se examinaron aleatoriamente a 64 pacientes hospitalizados en el Servicio de Medicina del Hospital San José. A aquellos con signos clínicos de onicomicosis pedis se les realizó un examen micológico directo (MD) y estudio histopatológico de un corte de uña teñido con PAS (Bp/PAS). Muestra de 64 pacientes, un 78,1% presentó onicomicosis pedis clínica y en un 70,3% se confirmó el diagnóstico con MD y/o Bp/PAS positivo. De los pacientes con onicomicosis confirmada, el promedio de edad fue de 67,8 +/- 12,3 años. Un 44% correspondió al sexo femenino y un 56% al sexo masculino. La onicomicosis pedis en el servicio de medicina interna del Hospital San José es una condición frecuente. El conjunto de MD y Bp/PAS podría ser considerado como una buena alternativa diagnóstica. (AU)

Onychomycosis of the toenails has a global prevalence of 4,3% and can reach up to 8,9% in hospitalized patients. It has been hypothesized that it is widely under diagnosed. Aged patients with multiple diseases have an increased risk of Onychomycosis and its complications. 64 patients of the internal medicine ward were randomly selected. Those who had clinical signs of onychomycosis of the toenails were tested with direct microscopy and histological study of the nail plate with PAS staining. Of the 64 patients, 78,1% (50) had clinical signs of onychomycosis of the toenails and in 70,3% (45) the diagnosis was confirmed either by direct microscopy and/or by histological study of the nail plate with PAS staining. The mean age for the group with onychomycosis was 67,8 +/- 12,3 ages. 44% were female and 56% were male. Onychomycosis of the toenails is a frequent condition at the internal medicine ward of the San José Hospital. The direct microscopy together with the histological study of the nail plate with PAS staining seem to be a good diagnosis alternative. (AU)

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.

First direct measurement of the 2H(α,γ)6Li cross section at big bang energies and the primordial lithium problem.

Recent observations of (6)Li in metal poor stars suggest a large production of this isotope during big bang nucleosynthesis (BBN). In standard BBN calculations, the (2)H(α,γ)(6)Li reaction dominates (6)Li production. This reaction has never been measured inside the BBN energy region because its cross section drops exponentially at low energy and because the electric dipole transition is strongly suppressed for the isoscalar particles (2)H and α at energies below the Coulomb barrier. Indirect measurements using the Coulomb dissociation of (6)Li only give upper limits owing to the dominance of nuclear breakup processes. Here, we report on the results of the first measurement of the (2)H(α,γ)(6)Li cross section at big bang energies. The experiment was performed deep underground at the LUNA 400 kV accelerator in Gran Sasso, Italy. The primordial (6)Li/(7)Li isotopic abundance ratio has been determined to be (1.5 ± 0.3) × 10(-5), from our experimental data and standard BBN theory. The much higher (6)Li/(7)Li values reported for halo stars will likely require a nonstandard physics explanation, as discussed in the literature.

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.

Activation measurement of the 3He(alpha,gamma)7Be cross section at low energy.

The nuclear physics input from the 3He(alpha,gamma)7Be cross section is a major uncertainty in the fluxes of 7Be and 8B neutrinos from the Sun predicted by solar models and in the 7Li abundance obtained in big-bang nucleosynthesis calculations. The present work reports on a new precision experiment using the activation technique at energies directly relevant to big-bang nucleosynthesis. Previously such low energies had been reached experimentally only by the prompt-gamma technique and with inferior precision. Using a windowless gas target, high beam intensity, and low background gamma-counting facilities, the 3He(alpha,gamma)7Be cross section has been determined at 127, 148, and 169 keV center-of-mass energy with a total uncertainty of 4%. The sources of systematic uncertainty are discussed in detail. The present data can be used in big-bang nucleosynthesis calculations and to constrain the extrapolation of the 3He(alpha,gamma)7Be astrophysical S factor to solar energies.

[Prevalence and genotypes of hepatitis C virus in blood donors and in patients with chronic liver disease and hepatocarcinoma in a Chilean population]. / Prevalencia y genotipos del virus de la hepatitis C en donantes de sangre y en pacientes con enfermedad hepática crónica y hepatocarcinoma en población Chilena.

BACKGROUND: The impact of hepatitis C virus infection in Chile has not been well established. AIM: To assess hepatitis C virus infection in normal Chileans and in patients with liver disease. SUBJECTS AND METHODS: Antibodies against hepatitis C virus were investigated in 21,000 blood donors, 133 patients with non alcoholic chronic liver disease and in 50 patients with hepatocarcinoma. Viral RNA was studied by polymerase chain reaction in all positive blood donors, in 51 patients with chronic liver disease and in all patients with hepatocarcinoma. Hepatitis C virus genotype was established using restriction fragment length polymorphism in 118 RNA positive samples. RESULTS: In blood donors, a 0.3% prevalence of positive antibodies was found. The figure for chronic liver disease was 53% and for hepatocarcinoma, 48%. Viral RNA was detected in 100% of patients with chronic liver disease and hepatocarcinoma and in 68% of blood donors with positive antibodies. Genotype 1b was identified in all infected patients with hepatocarcinoma, in 86% of patients with chronic liver disease and in 46% of blood donors. CONCLUSIONS: Hepatitis C virus infection is an important etiologic agent for chronic liver disease in Chile. The predominance of genotype 1b among patients with the most severe form of liver disease is in agreement with observations made abroad.

Genotipo del virus C de la hepatitis en pacientes con porfiria cutanea tarda / Genotype of the hepatitis virus C in patients with porphyria cutanea tarda

En pacientes con porfiria cutánea tarda (PCT) se ha demostrado alta prevalencia del anticuerpo del virus C de la hepatitis (anti-VCH) y del propio virus. Previamente hemos informado una prevalencia de anti-VCH de 53 por ciento, y de 80 por ciento entre aquellos pacientes con PCT esporádica. La PCT se asocia frecuentemente a daño hepático crónico,desconociéndose su origen. Se ha postulado que el VCH, directa o imdirectamente, modificaría la actividad de la uroporfirinógeno decarboxilasa(URO-D) hepática, alteración carterística de la PCT, y por lo tanto la enfermedad sería adquirida y no genética. Podría esperarse que la frecuencia e intensidad de la hepatopatías en los pacientes con PCT fuera mayor en aquellos pacientes portadores del Anti-VCH(AU)

Genotipo del virus C de la hepatitis en pacientes con porfiria cutanea tarda / Genotype of the hepatitis virus C in patients with porphyria cutanea tarda

En pacientes con porfiria cutánea tarda (PCT) se ha demostrado alta prevalencia del anticuerpo del virus C de la hepatitis (anti-VCH) y del propio virus. Previamente hemos informado una prevalencia de anti-VCH de 53 por ciento, y de 80 por ciento entre aquellos pacientes con PCT esporádica. La PCT se asocia frecuentemente a daño hepático crónico,desconociéndose su origen. Se ha postulado que el VCH, directa o imdirectamente, modificaría la actividad de la uroporfirinógeno decarboxilasa(URO-D) hepática, alteración carterística de la PCT, y por lo tanto la enfermedad sería adquirida y no genética. Podría esperarse que la frecuencia e intensidad de la hepatopatías en los pacientes con PCT fuera mayor en aquellos pacientes portadores del Anti-VCH

[Clinical study of 113 cases of malignant melanoma]. / Estudio clinico de 113 casos de melanoma maligno.

Malignant Melanoma (MM) incidence rate is increasing faster than many other cancer at present time. Its epidemiological and clinical behavior varies within countries. We have studied 113 cases of cutaneous melanoma from 1982-1993, that represents until now the largest series of MM studied in Chile. Superficial Spreading Melanoma was the most common type of MM with 37.5% of total cases followed by Nodular Melanoma 31.2%. Acral Melanoma 22.1%, and Lentigo Malignant Melanoma with 7.8%. MM favored females with 60.2% (n = 68) and males constituted 39.8% (n = 45) of all cases. Median age at diagnosis was 54 years. Primary more frequent location for man was thorax (36.4%) and lower extremities for women (28.6%). Hemorrhage, ulceration and rapid growth of a previously pigmented lesion as the primary cause for first medical visit were associated with high level of invasion, generally over 2 mm. thick. Color change and pruritus were associated with lower level of invasion. Patients in stage I (78.3%) had 1.35 mm of median invasive thickness in the primary lesion and patients in stage II (15.7%) had 3.03 mm.

Differential expression of the common beta and specific alpha chains of the receptors for GM-CSF, IL-3, and IL-5 in endothelial cells.

The present study was designed to reexamine the interaction of granulocyte-macrophage colony-stimulating factor (GM-CSF) with endothelial cells (EC) and to investigate the expression of CSF receptor chains in these cells. In agreement with previous data, GM-CSF induced directional migration and, to a lesser degree, proliferation of human umbilical vein EC. When compared to basic fibroblast growth factor, GM-CSF was comparable in terms of chemotactic activity and was substantially less active in terms of proliferation. Binding studies confirmed the presence of receptors for GM-CSF (GM-CSFR) on EC. The expression of the beta chain common to the GM-CSFR, IL-3 receptor, and IL-5 receptor, as well as of the individual alpha chains, was studied by Northern analysis and/or reverse transcription and polymerase chain reaction. EC expressed high levels of the common beta chain transcripts. Expression of the alpha(GM) and alpha(IL-5) chain mRNA was minimal or absent in normal EC, though the transformed ECV304 endothelial cell line had substantial amounts of alpha(GM) chain mRNA. Unexpectedly, EC expressed alpha(IL-3) chain transcripts. IL-3 induced migration of EC across polycarbonate filters, whereas IL-5 was inactive.

Proliferative and migratory responses of murine microvascular endothelial cells to granulocyte-colony-stimulating factor.

Microvascular murine endothelial cells lines transformed by middle T oncogene of polyoma virus maintain the biological characteristics of nontransformed microvascular endothelial cells (EC). By using cell lines originated from different anatomical districts (thymus, brain, heart, and skin), we demonstrated that murine granulocyte-colony-stimulating factor (G-CSF) induces proliferation of murine microvascular endothelial cells at nanomolar concentrations without any cooperation with fetal calf serum. The proliferative effect on murine cells is less than that elicited by epidermal growth factor (EGF), used as standard for this function. G-CSF also promotes the migration of tEnd.1 endothelial cell line assayed by Boyden chamber technique. The analysis of transcript for G-CSF receptor (G-CSFR) by Northern blot hybridization and by reverse-transcriptase polymerase chain reaction (RT-PCR) shows that these cell lines have specific mRNA, with the size of that present in myeloid cells. These results indicate that G-CSF operates in the microvascular endothelial cells by a mechanism related to the presence of a specific receptor.

Recent developments in the cell biology of granulocyte-macrophage colony-stimulating factor and granulocyte colony-stimulating factor: activities on endothelial cells.

Granulocyte-macrophage colony-stimulating factor and granulocyte colony-stimulating factor were considered as growth and differentiation factors restricted to hematopoietic cells. It was recently found that non-hematopoietic cells, including endothelial cells, respond to these cytokines. In this review we describe their effects on endothelial cells, underlining their role in the behavior and survival of the microenvironment of bone marrow, in the angiogenesis process related to the progression of solid tumors and of vascular tumors, and in the homing of lymphocytes.