Codici di calcolo per la termofluidodinamica: descrizione e utilizzo di STAR-CD

Si vuole fornire una descrizione delle potenzialità ed una guida pratica all'utilizzo del codice di calcolo per la termofluidodinamica STAR-CD sulle macchine per il supercalcolo del CILE

Note: Accounting for pressure effects on the calculated equilibrium structure of glassy GeSe2:

First-principles molecular dynamics (FPMD) data on the structural properties of glassy GeSe2 under ambient conditions are produced by carefully considering and minimizing the effect of a residual pressure on the periodic system. When compared to previous FPMD results, this strategy leads to an improved agreement between theory and neutron diffraction experiments

Preliminary study on the use of the 137 Cs method for soil erosion investigation in the pampean region of Argentina

Soil erosion is the most important degradation process in A rgentine. According to the estimation of 4.9 millon ha in Pampa Ondulada Region, 1.600.000 ha (36% of agricultural soils) are affected by the erosion. Field measurements of soil erosion and sediment deposition using classical techniques are difficult, time consuming, and expensive but indispensable to feed the prediction models for conservation practices design and fa rm planning. Many authors have reported that the measurement of fallout nuclides is useful tool to characterize geomorphical processes. Walling and He proposes models for conve rting 137Cs depletion/enrichment amounts to net soil loss/deposition. These models are based in the comparison between a reference 137Cs profile in a long term undisturbed site (control site) and the 137Cs profiles in the suspected eroded or deposited sites in the landscape. The aim of this study is to provide a complete and well representative set of data on the erosion intensity in topographical conditions for the Pampa Ondulada Region in A rgentine by using a tracer technique. The study area is a small watershed (about 300 ha), located in Arroyo del Tala medium basin, within Partido of San Pedro in Buenos Aires Province, Argentine. This paper presents a group of results from a detailed investigation of erosion and sediment delivery, within a 49 ha cultivated field study site in this watershed. The base of sampling strategy is the grid approach. A reference inventory, representing the local fallout input, was searched for at a site experiencing neither erosion nor deposition. Radiocaesium analyses were made at the Nuclear Regulatory Authority Laboratory by a GE Hp detector. To make an interpretation of 137Cs distribution of soil losses and sedimentation, the Mass Balance Model 2 was used (Walling and He 1997). The erosion/deposition rates from Mass Balance Model 2 are in the range of 0 to -30 t·ha-1·y-1 for erosion, and 0 to 19 t·ha-1·y-1 for deposition, and these values matched well, with the rates of erosion obtained by classical methods. The 137Cs spatial and depth distribution are showed in a map, and enabled to study the relationship of the erosion to the topography, and a good discrimination in subclasses within moderate erosion class and sedimentation class

Human kallikrein gene 5 (KLK5) expression is an indicator of poor prognosis in ovarian cancer

Kallikrein gene 5 (KLK5, also known as KLK-L2), located on chromosome 19q13.4, is one of the newly identified members of the kallikrein gene family, which is a subgroup of the serine protease enzyme family. In normal human tissues, KLK5 is highly expressed in skin, mammary gland and testis. Preliminary RT-PCR analysis has indicated that KLK5 is expressed in a subset of ovarian tumours. We have thus hypothesized that KLK5 may be a new prognostic indicator in ovarian cancer. We have examined the mRNA expression of KLK5 in 142 malignant ovarian tissues. Tumours were pulverized, total RNA was extracted, and cDNA was prepared by reverse transcription. KLK5 was amplified by PCR using gene specific primers, and the identity of the PCR product was verified by sequencing. Ovarian tissues were then classified as KLK5 positive or negative, based on ethidium bromide staining of the PCR product on agarose gels. KLK5 was found to be highly expressed in 58/142 (41%) of ovarian cancer samples while its level of expression was very low in normal ovarian tissues. We found a strong positive relation between KLK5 expression and tumour grade (P = 0.006) and disease stage (P = 0.027). Univariate survival analysis revealed that patients with ovarian tumours positive for KLK5 expression had an increased risk for relapse and death (P = 0.018 and 0.022, respectively). In multivariate analysis, KLK5 expression showed independent prognostic value only in the subset of tumours with lower grade disease (grades I and II). We conclude that KLK5 expression is associated with more aggressive forms of epithelial ovarian carcinoma and has indepdent prognostic value in low grade tumours. © 2001 Cancer Research Campaign http://www.bjcancer.co

Steroid Hormone Regulation and Prognostic Value of the Human Kallikrein Gene 14 in Ovarian Cancer

n/

Supercell technique for total-energy calculations of finite charged and polar systems

We study the behavior of total-energy supercell calculations for dipolar molecules and charged clusters. Using a cutoff Coulomb interaction within the framework of a plane-wave basis set formalism, with all other aspects of the method (pseudopotentials, basis set, exchange-correlation functional) unchanged, we are able to assess directly the interaction effects present in the supercell technique. We find that the supercell method gives structures and energies in almost total agreement with the results of calculations for finite systems, even for molecules with large dipole moments. We also show that the performance of finite-grid calculations can be improved by allowing a degree of aliasing in the Hartree energy, and by using a reciprocal space definition of the cutoff Coulomb interaction

Structural properties of glassy Ge2Se3 from first-principles molecular dynamics

The structural properties of glassy Ge2Se3 were studied in the framework of first-principles molecular dynamics by using the Becke-Lee-Yang-Parr scheme for the treatment of the exchange-correlation functional in density functional theory. Our results for the total neutron structure factor and the total pair distribution function are in very good agreement with the experimental results. When compared to the structural description obtained for liquid Ge2Se3, glassy Ge2Se3 is found to be characterized by a larger percentage of fourfold coordinated Ge atoms and a lower number of miscoordinations. However, Ge-Ge homopolar bonds inevitably occur due to the lack of Se atoms available, at this concentration, to form GeSe4 tetrahedra. Focusing on the family of glasses GexSe1-x, the present results allow a comparison to be carried out in reciprocal and real space among three prototypical glassy structures. The first was obtained at the stoichiometric composition (glassy GeSe2), the second at a Se-rich composition (glassy GeSe4) and the third at a Ge-rich composition (glassy Ge2Se3). All networks are consistent with the “8 - N” rule, in particular, glassy GeSe4, which exhibits the highest degree of chemical order. The electronic structure of glassy Ge2Se3 has been characterized by using the Wannier localized orbital formalism. The analysis of the Ge environment shows the presence of dangling, ionocovalent Ge-Se, and covalent bonds, the latter related to Ge-Ge connections. DOI: 10.1103/PhysRevB.86.224201This work was granted access by GENCI (Grand Equipement National de Calcul Intensif) under allocation 2011095071 to the HPC resources of CCRT/CINES/IDRI

The structure of liquid GeSe revisited: A first principles molecular dynamics study:

Early first-principles molecular dynamics results on liquid GeSe were characterized by shortcomings in the description of Ge-Ge (and to a lesser extent Se-Se) short range correlations. In that case the exchange-correlation functional adopted was the one devised by Perdew and Wang (PW91). In the search of improvements in the atomic-scale modelling of this liquid, we have produced new sets of data by employing two different schemes for the exchange-correlation part within the density functional theory approach. The two functionals selected are those proposed by Becke, Lee, Yang, and Parr (BLYP) and by Perdew, Burke, and Ernzerhof (PBE). The PBE results turned out to be quite similar to the PW91 ones. The BLYP results feature instead a better account of the Ge-Ge first shell of neighbors, correctly exhibiting two clear maxima separated by a deep minimum. Due to the increase in the number of the tetrahedral structural units, the atomic mobility of Ge and Se atoms in the network is reduced with respect to the PW91 case. This brings the diffusion coefficients of the two species down to values close to those of liquid Ge2Se3 and liquid GeSe2. (C) 2013 AIP Publishing LLC