Nuclear astrophysics: Recent results on CNO-cycle reactions and AGB nucleosynthesis

Nuclear astrophysics aims to measure nuclear-reaction cross sections of astrophysical interest to be included into models to study stellar evolution and nucleosynthesis. Low energies, < 100 keV, are requested for this is the window where these processes are more effective. Two effects have prevented to achieve a satisfactory knowledge of the relevant nuclear processes, namely the Coulomb barrier exponentially suppressing the cross section and the presence of atomic electrons. These difficulties have triggered theoretical and experimental investigations to extend our knowledge down to astrophysical energies. For instance, indirect techniques such as the Trojan Horse Method and new experimental facilities such as deep underground laboratories have been devised yielding new cutting-edge results

Determining the 13C(α, n)16O absolute cross section through the concurrent application of ANC and THM and astrophysical consequences for the s-process in AGB-LMSs.

The 13 C( α , n) 16 O reaction is considered to be the most important neutron source for the s -process main component in low-mass asymptotic giant branch stars. No direct experimental data exist at very low energies and measurements performed through direct techniques show inconsistent results, mostly in their absolute values. In this context, we reversed the usual normalization procedure combining two indirect approaches, the asymptotic normalization coefficient and the Trojan Horse Method, to unambiguously determine the absolute value of the 13 C( α , n) 16 O astrophysical S ( E )-factor in the most relevant energy-region for astrophysics. Adopting the new reaction rate for the n-source in the NEWTON s -process nucleosynthesis code, astrophysical calculations show only limited variations, less than 1%, for those nuclei whose production is considered to be totally due to slow neutron captures

First time evidence of pronounced plateaus right above the Coulomb barrier in 8Li + 4He fusion

We investigate unprecedented experimental information on the fusion reaction induced by the radioactive projectile 8 Li on a 4 He gas target, at center-of-mass energies between 0.6 and 5 MeV. The main issue is the tendency of the dimensionless fusion cross section σfπƛ2 to form well visible plateaus alternated to steep rises. This finding is likely to be the most genuine consequence of the discrete nature of the intervening angular momenta observed so far in fusion reactions right above the Coulomb barrier. A partial-wave analysis, exclusively based on a pure quantal penetration fusion model and sensitive to the interaction potential, identifies a remarkably low-height barrier

Design of a Lambda system for population transfer in superconducting nanocircuits

The implementation of a Lambda scheme in superconducting artificial atoms could allow detec- tion of stimulated Raman adiabatic passage (STIRAP) and other quantum manipulations in the microwave regime. However symmetries which on one hand protect the system against decoherence, yield selection rules which may cancel coupling to the pump external drive. The tradeoff between efficient coupling and decoherence due to broad-band colored Noise (BBCN), which is often the main source of decoherence is addressed, in the class of nanodevices based on the Cooper pair box (CPB) design. We study transfer efficiency by STIRAP, showing that substantial efficiency is achieved for off-symmetric bias only in the charge-phase regime. We find a number of results uniquely due to non-Markovianity of BBCN, namely: (a) the efficiency for STIRAP depends essentially on noise channels in the trapped subspace; (b) low-frequency fluctuations can be analyzed and represented as fictitious correlated fluctuations of the detunings of the external drives; (c) a simple figure of merit for design and operating prescriptions allowing the observation of STIRAP is proposed. The emerging physical picture also applies to other classes of coherent nanodevices subject to BBCN.Comment: 14 pages, 11 figure

Design and development of a data warehouse for a company trading natural stone

Progettazione e realizzazione di un data warehouse e di un sistema di business intelligence per il supporto ai processi di decisione delle società del gruppo R.E.D. Graniti riguardo vendite, giacenze e costi, utilizzando tool Oracle. Design and development of a data warehouse and a business intelligence system to support R.E.D. Graniti group's business decisions for sales, stocks and costs, using Oracle tools

Genetics of Parkinson’s Disease: The Role of Copy Number Variations

Parkinson’s disease (PD), the second most common progressive neurodegenerative disorder, was long believed to be a non-genetic sporadic origin syndrome. The identification of distinct genetic loci responsible for rare Mendelian forms of PD has represented a revolutionary breakthrough, allowing to discover novel mechanisms underlying this debilitating still incurable condition. Along with single-nucleotide polymorphisms (SNPs), other kinds of DNA molecular defects have emerged as significant disease-causing mutations, including large chromosomic structural rearrangements and copy number variations (CNVs). Due to their size variability and to the different sensitivity and resolution of detection methodologies, CNVs constitute a particular challenge in genetic studies and the pathogenetic or susceptibility impact of specific CNVs on PD is currently under debate. In this chapter, we will review the current literature and bioinformatic data describing the involvement of CNVs on PD pathobiology. We will discuss the recently highlighted role of PARK2 heterozygous CNVs, the possible common founder effects of PD gene rearrangements and the importance to map genetic breakpoints. We will also add a summary about the current available molecular methods and bioinformatics web resources to detect and interpret CNVs. Assessing the global genome-wide burden of large CNVs and elucidating the role of de novo rare structural variants on PD may reveal new candidate genes and consequently ameliorate diagnosis and counselling of mutations carriers

PRKN (arkin RBR E3 ubiquitin protein ligase )

PARK2 (also known as Parkin RBR E3 ubiquitin protein ligase) is one of the largest genes in our genome. It undergoes an extensive alternative splicing both at transcript and protein level, producing multiple transcript variants and distinct protein isoforms. The precise function of PARK2 is still not clear; however, the encoded protein is a component of a multiprotein E3 ubiquitin ligase complex that mediates the targeting of substrates for proteasomal degradation. Mutations in this gene cause Parkinson disease and autosomal recessive juvenile Parkinson disease. Further molecular defects have been linked to other human malignancies. Here, we review some major data on PARK2, concerning the genetic structure, the transcription regulation, the encoded protein and functions, and its implication in human disease

The bistable system: an archetypal model for complex systems

Bistable systems often play the role of archetypal models to understand the dynamical behavior of complex systems. Examples range from microphysics to macrophysics, bìology, chemistry and also econophysics. Moreover the statistical mechanics is essential to study the physical properties of complex systems and to investigate stochastic systems in which the microscopic degrees of freedom behave collectively over large scales. We investigate the nonlinear relaxation in a bistable system in classical and quantum systems. (i) As a first classical system, the role of the multiplicative and additive noise in the mean life time of the metastable state of an asymmetric bistable system is investigated. Thìs model is useful to describe the dynamical behavior of an out of equilibrium Ising spin system. Nonmonotonic behavior of the average lifetime as a function of both additive and multiplicative noise source intensities ìs found. (ii) The role of a non-Gaussian Lévy noise on the nonlinear dynamics of: a) a partide moving in a metastable system, b) an ecosystem composed by two competing species interacting with the surrounding environment, and c) a short overdamped Iosephson junction is investigated. a) By using the backward fractional Fokker-Planck equation we investigate the barrier crossing event and the nonlinear relaxation time for a metastable system; b) In the ecosystem, the role of two non-Gaussian noise sources in the exclusion and coexistence regimes is analyzed. Quasiperiodic oscillations and stochastic resonance phenomenon in the dynamics of the competing specìes are found: c) In the short overdamped Iosepbson, the mean escape time of the junction is investigated considering Gaussian, Cauchy- Lorentz and Lévy-Smìrnov probability distributions of the noise signals. In these conditions we find resonant activation and the first evidence of noise enhanced stability in a metastable system in the presence of Lévy noise. For Cauchy- Lorentz noise source, trapping phenomena and power law dependence on the noise intensity are observed. (iii) Finally the dynamics of a quantum particle subject to an asymmetric bistable potential and interacting with a thermal reservoir is investigated. We obtain the time evolution of the population distributions in the position eigenstates of the particle, for dìfferent values of the coupling strength with the thermal bath. The calculation is carried out by using the Feynman-Vernon functional under the discrete variable representation

THE 8 Li(α, n) 11 B REACTION RATE AT ASTROPHYSICAL TEMPERATURES

At temperatures (0.5-1.2) × 109 K, the 8Li + 4He → 11B+n reaction can allow for 12C and heavier element production in the framework of the inhomogeneous big bang nucleosynthesis. At temperatures (2.5-5) × 109 K, it can influence the production of seed nuclei, later burnt to heavier elements by means of rapid neutron capture reactions, during Type II supernova explosions. Previous determinations of the reaction rate show an untenable disagreement. In this work, a new reaction rate calculation is proposed for the intervals of astrophysical interest. This new recommendation turns out to be up to a factor of five larger than the most recent rate in the literature, thus enforcing the role of 8Li + 4He → 11B+n as a candidate for key astrophysical reactions. The analytical expression of the recommended reaction rate is given