Phase transformation B1 to B2 in TiC, TiN, ZrC and ZrN under pressure

Phase stability of various phases of MX (M = Ti, Zr; X = C, N) at equilibrium and under pressure is examined based on first-principles calculations of the electronic and phonon structures. The results reveal that all B1 (NaCl-type) MX structures undergo a phase transition to the B2-structures under high pressure in agreement with the previous total-energy calculations. The B1-MX structures are dynamically stable under very high pressure (210-570 GPa). The pressure-induced B2 (CsCl-type) MC phases are dynamically unstable even at high pressures, and TiN and ZrN are found to crystallize with the B2-structure only at pressures above 55 GPa. The first-order B1-to-B2 phase transition in these nitrides is not related to the softening of phonon modes, and the dynamical instability of B2-MX is associated with a high density of states at the Fermi level.Comment: 9 pages, 4 figure

Tackling Prejudice and Discrimination Towards Families with Same-Sex Parents: An Exploratory Study in Italy

Though studies have shown that the sexual orientation of parents does not influence their parenting skills or the well-being of their children, prejudice against same-sex families is still very widespread. Research has not sufficiently explored the ways in which parents tackle this prejudice. Using qualitative methodologies, in particular textual analyses, this study has analysed the discourse used by same-sex families to handle the prejudices that they face. The results highlighted that conflicts, which may even be ideological in nature, are sometimes created between traditional families and “atypical” families. These often result in estrangement and isolation from their own family and the communities to which they belong, in turn damaging the growth of the children involved. Furthermore, means for moving beyond conflict, sharing experiences and effectively tackling prejudices are also discussed

High accuracy short-term PWV operational forecast at the VLT and perspectives for sky background forecast

In this paper we present the first results ever obtained by applying the autoregressive (AR) technique to the precipitable water vapour (PWV). The study is performed at the Very Large Telescope. The AR technique has been recently proposed to provide forecasts of atmospheric and astroclimatic parameters at short time scales (up to a few hours) by achieving much better performances with respect to the 'standard forecasts' provided early afternoon for the coming night. The AR method uses the real-time measurements of the parameter of interest to improve the forecasts performed with atmospherical models. We used here measurements provided by LHATPRO, a radiometer measuring continuously the PWV at the VLT. When comparing the AR forecast at 1h to the standard forecast, we observe a gain factor of $\sim$ 8 (i.e. $\sim$ 800 per cent) in terms of forecast accuracy. In the PWV $\leq$ 1 mm range, which is extremely critical for infrared astronomical applications, the RMSE of the predictions is of the order of just a few hundredth of millimetres (0.04 mm). We proved therefore that the AR technique provides an important benefit to VLT science operations for all the instruments sensitive to the PWV. Besides, we show how such an ability in predicting the PWV can be useful also to predict the sky background in the infrared range (extremely appealing for METIS). We quantify such an ability by applying this method to the NEAR project (New Earth in the Alpha Cen region) supported by ESO and Breakthrough Initiatives

THERMODYNAMICS OF FE-CU ALLOYS AS DESCRIBED BY A CLASSIC POTENTIALS

The Fe-Cu system is of relevance to the nuclear industry because of the deleterious consequences of Cu precipitates in the mechanical properties of Fe. Several sets of classical potentials are used in molecular dynamics simulations studies of this system, in particular that proposed by Ludwig et al. (Modelling Simul. Mater. Sci. Eng. 6, 19 (1998)). In this work we extract thermodynamic information from this interatomic potentials. We obtain equilibrium phase diagram and find a reasonable agreement with the experimental phases in the regions of relevance to radiation damage studies. We compare the results with the predicted phase diagram based on other potential, as calculated in previous work. We discuss the disagreements found between the phase diagram calculated here and experimental results, focusing on the pure components and discuss the applicability of these potentials; finally we suggest an approach to improve existing potentials for this system

Modelling Thermodynamics of Alloys for Fusion Application

This research has two main objectives: (1) On one side is the development of computational tools to evaluate alloy properties, using the information contained in thermodynamic functions to improve the ability of classic potentials to account for complex alloy behavior. (2) On the other hand, to apply the tools so developed to predict properties of alloys under irradiation. Atomistic simulations of alloys at the empirical level face the challenge of correctly modeling basic thermodynamic properties. In this work we develop a methodology to generalize many-body classic potentials to incorporate complex formation energy curves. Application to Fe-Cr allows us to predict the implications of the ab initio results of formation energy on the phase diagram of this alloy

Raman scattering from fractals. Simulation on large structures by the method of moments

We have employed the method of spectral moments to study the density of vibrational states and the Raman coupling coefficient of large 2- and 3- dimensional percolators at threshold and at higher concentration. We first discuss the over-and under-flow problems of the procedure which arise when -like in the present case- it is necessary to calculate a few thousand moments. Then we report on the numerical results; these show that different scattering mechanisms, all {\it a priori} equally probable in real systems, produce largely different coupling coefficients with different frequency dependence. Our results are compared with existing scaling theories of Raman scattering. The situation that emerges is complex; on the one hand, there is indication that the existing theory is not satisfactory; on the other hand, the simulations above threshold show that in this case the coupling coefficients have very little resemblance, if any, with the same quantities at threshold.Comment: 26 pages, RevTex, 8 figures available on reques

Assessment of the Precision ID Identity Panel kit on challenging forensic samples

The performance of the Precision ID Identity Panel (Thermo Fisher Scientific) was assessed on a set of 87 forensic samples with different levels of degradation for which a reference sample from the \u201csame donor\u201d or from a \u201cfirst degree relative\u201d was available. PCR-MPS analysis was performed with DNA input ranging from 1 ng to 12 pg and through 21-26 PCR cycles, in replicate tests, and a total number of 255 libraries were sequenced on the Ion Personal Genome Machine\u2122 (PGM\u2122) System. The evaluation of the molecular data allowed to set a fix threshold for locus call at 50 x which suitably worked even when low amounts of degraded DNA (12 pg) were investigated. In these analytical conditions, in fact, 25 PCR cycles allowed the genotyping of about 50% and 35% of the autosomal and the Y-specific markers on average, respectively, for each single amplification with a negligible frequency of drop ins (0.01 %). On the other hand, drop out artefacts reached 18-23% when low copy number and degraded DNA samples were studied, with surviving alleles showing more than 600 reads in 2.9 % of the cases. Our data pointed out that the Precision ID Identity Panel allowed accurate typing of almost any amount of good quality/moderately degraded DNA samples, in duplicate tests. The analysis of low copy number DNAs evidenced that the same allele of a heterozygous genotype could be lost twice, thus suggesting that a third amplification could be useful for a correct genotype assignment in these peculiar cases. Using the consensus approach, a limited number of genotyping errors were computed and about 37% of the autosomal markers was finally typed with a corresponding combined random match probability of at least 1.6 x 10-13, which can be considered an excellent result for this kind of challenging samples. In the end, the results presented in this study emphasize the crucial role of the expert opinion in the correct evaluation of artefacts arising from PCR-MPS technology that could potentially lead to genetic mistyping