Study of carbon-doped Mn3Ga thin films with enhanced magnetization

Carbon-doped Mn3Ga thin films were grown on Si/SiO2 substrates using rf magnetron sputtering technique and they present an enhancement of their magnetization. In this work we focus on the structural stress, theoretical calculations and magnetization analysis (using both Bloch's and Kneller's laws). The residual stress component has been calculated by means of x-ray diffraction in gracing incidence, using the ? method for multiple crystallographic reflections. We have observed an increase of the cell volume or positive (tensile) strain, which is higher near the surface of the film. The existence of induced magnetism in Mn3GaC0.25, with C entering in interstitial positions has been investigated by first-principles calculations, using the projector-augmented-wave method, within the generalized gradient approximation. Spin charge distributions and magnetic moments associated with each ion, were analyzed by performing a Bader charge analysis. Noteworthily, in spite of being a thin film, the magnetic behavior of the sample can be well described considering it formed by magnetic nanoparticles. Magnetic field and temperature dependence of the magnetization measurements were used to evaluate the Bloch and Kneller exponents, showing that dipolar interactions take place between Mn3GaC0.25 nanoparticle

Marine Biodiversity in the Caribbean: Regional Estimates and Distribution Patterns

This paper provides an analysis of the distribution patterns of marine biodiversity and summarizes the major activities of the Census of Marine Life program in the Caribbean region. The coastal Caribbean region is a large marine ecosystem (LME) characterized by coral reefs, mangroves, and seagrasses, but including other environments, such as sandy beaches and rocky shores. These tropical ecosystems incorporate a high diversity of associated flora and fauna, and the nations that border the Caribbean collectively encompass a major global marine biodiversity hot spot. We analyze the state of knowledge of marine biodiversity based on the geographic distribution of georeferenced species records and regional taxonomic lists. A total of 12,046 marine species are reported in this paper for the Caribbean region. These include representatives from 31 animal phyla, two plant phyla, one group of Chromista, and three groups of Protoctista. Sampling effort has been greatest in shallow, nearshore waters, where there is relatively good coverage of species records; offshore and deep environments have been less studied. Additionally, we found that the currently accepted classification of marine ecoregions of the Caribbean did not apply for the benthic distributions of five relatively well known taxonomic groups. Coastal species richness tends to concentrate along the Antillean arc (Cuba to the southernmost Antilles) and the northern coast of South America (Venezuela – Colombia), while no pattern can be observed in the deep sea with the available data. Several factors make it impossible to determine the extent to which these distribution patterns accurately reflect the true situation for marine biodiversity in general: (1) highly localized concentrations of collecting effort and a lack of collecting in many areas and ecosystems, (2) high variability among collecting methods, (3) limited taxonomic expertise for many groups, and (4) differing levels of activity in the study of different taxa

Optimasi Portofolio Resiko Menggunakan Model Markowitz MVO Dikaitkan dengan Keterbatasan Manusia dalam Memprediksi Masa Depan dalam Perspektif Al-Qur`an

Risk portfolio on modern finance has become increasingly technical, requiring the use of sophisticated mathematical tools in both research and practice. Since companies cannot insure themselves completely against risk, as human incompetence in predicting the future precisely that written in Al-Quran surah Luqman verse 34, they have to manage it to yield an optimal portfolio. The objective here is to minimize the variance among all portfolios, or alternatively, to maximize expected return among all portfolios that has at least a certain expected return. Furthermore, this study focuses on optimizing risk portfolio so called Markowitz MVO (Mean-Variance Optimization). Some theoretical frameworks for analysis are arithmetic mean, geometric mean, variance, covariance, linear programming, and quadratic programming. Moreover, finding a minimum variance portfolio produces a convex quadratic programming, that is minimizing the objective function ðð¥with constraintsð ð 𥠥 ðandð´ð¥ = ð. The outcome of this research is the solution of optimal risk portofolio in some investments that could be finished smoothly using MATLAB R2007b software together with its graphic analysis

Search for supersymmetry in events with one lepton and multiple jets in proton-proton collisions at root s=13 TeV

Peer reviewe

Search for anomalous couplings in boosted WW/WZ -> l nu q(q)over-bar production in proton-proton collisions at root s=8TeV

Peer reviewe

ANÁLISIS DE CRECIMIENTO Y ESORULACIÓN IN VITRO DE MUTANTES DEL HONGO Trichoderma atroviride AFECTADAS EN SU RESPUESTA A LUZ AZUL

El género Trichoderma constituye un grupo diverso de especies de hongos saprofíticos, comúnmente establecidas en el suelo sobre madera en descomposición y restos de plantas (Jensen y Wolffhechel, 1995; Smith, 1995), la presencia de varias especies difiere entre hábitat y están influidas por las condiciones ambientales. Estas se pueden encontrar en el aire, partes aéreas de plantas, pero especialmente en suelos, incluyendo humus forestales (Samuels, 1996). Las especies del género Trichoderma se reproducen clonalmente mediante un ciclo de vida asexual en el que se alternan micelio y conidias o esporas asexuales. El micelio se caracteriza por poseer hifas más o menos ramificadas, tabicadas y con más de un núcleo por célula. Las conidias poseen un solo núcleo haploide, son ovoides, de color verde (excepcionalmente hialinas) y se forman sobre estructuras muy ramificadas o conidióforos que a su vez se sitúan sobre células especiales denominadas fiálides (Rosen et al., 1974). En determinadas condiciones nutricionales o frente a la desecación se producen otro tipo de estructuras de resistencia denominadas clamidosporas (Lewis y Papavizas, 1984). El micelio de las especies de Trichoderma crece a un ritmo rápido en cultivo con la producción de numerosas esporas de color verde, característica de este género. Utilizan un amplio rango de compuestos como fuente de carbono y nitrógeno, entre los que se encuentran monosacáridos, disacáridos (Danielson y Davey, 1973), polisacáridos complejos, purinas, pirimidinas y aminoácidos (Tye, 1973), taninos condensados y catequinas (Arrieta-Escobar, 1982)

Theoretical study of electric properties of zig-zag carbon nanotubes at low nitrogen concentration

We have performed a comparative study of electrical properties between pristine and nitrogen doped (at low concentration) single wall carbon nanotubes (SWNTs), for three zig-zag cases: (6,0), (8,0) and (9,0). The results were obtained through the Density Functional Theory (DFT) with the Generalized Gradient Approximation (GGA) in the relaxed CC bond length for the long-wavelength limit. The stability of the structures was determined by calculating total energies for the pristine and the N-doped structures. From the calculations of the energy loss function, we probed plasmon peak positions for the proposed quiralities. Keywords: DFT, Carbon nanotubes, Electrical propertie