Spin-polarized transport in ferromagnetic multilayered semiconductor nanostructures

The occurrence of inhomogeneous spin-density distribution in multilayered ferromagnetic diluted magnetic semiconductor nanostructures leads to strong dependence of the spin-polarized transport properties on these systems. The spin-dependent mobility, conductivity and resistivity in (Ga,Mn)As/GaAs,(Ga,Mn)N/GaN, and (Si,Mn)/Si multilayers are calculated as a function of temperature, scaled by the average magnetization of the diluted magnetic semiconductor layers. An increase of the resistivity near the transition temperature is obtained. We observed that the spin-polarized transport properties changes strongly among the three materials.Comment: 3 pages, 4 figure

Custos de transação e comportamento da base para o preço do milho em Rio Verde, GO.

O objetivo deste trabalho foi analisar o comportamento da base, que é a diferença entre o preço do milho de Rio Verde, GO, e o preço futuro do milho na BM&FBovespa de 3/1/2005 até 15/3/2011. Por conseguinte, a hipótese do estudo é que os custos de transação e as características regionais da comercialização do milho fazem que ocorra elevada divergência de preços entre os mercados. O modelo autorregressivo com threshold (TAR) foi usado para captar as importantes dimensões dos custos de transação. Os resultados estimados para o parâmetro TAR de 7,78% mostram uma fraca convergência entre os preços dos mercados e, por consequência, o enfraquecimento da base na região. Isso evidencia que os produtores minimizam custos de transação regionais e, por isso, estão mais preocupados com as transações de hedging privado no mercado físico, não recorrendo à bolsa de valores para proteção contra oscilação de preços

Análise dos canais de distribuição e dos custos de transação da cadeia produtiva da mandioca no município de Jussara-GO.

O objetivo geral deste estudo foi analisar os canais de distribuição e os custos de transação da mandioca Município de Jussara-GO. De antemão, sabe-se que o cultivo da mandioca possui grande importância para agricultura familiar, principalmente na área geográfica estudada. Os dados primários coletados em 22 glebas mostraram que maior parte da renda da propriedade advém do cultivo e da distribuição com as indústrias ?farinheiras? da região. Destarte, foi de suma importância elucidar os mecanismos, tanto de distribuição, quanto os custos de transação envolvidos no processo de comercialização entre produtores e as indústrias processadoras. Os atributos de frequência, incerteza e especificidade de ativos estão fortemente presentes e implicam em gargalos no processo de produção, pois 90% das transações são realizadas a mercado, sem nenhum tipo de acerto formal entre as partes envolvidas. Diante disto, a construção de reputação junto aos compradores e/ou fornecedores torna-se fundamental como instrumento de redução de custos de transação

Aperfeiçoamento do método para avaliação da deriva de inseticida granulado aplicado por via aérea em lavouras de arroz irrigado.

bitstream/item/31612/1/comunicado85.pd

COLDz: Karl G. Jansky Very Large Array discovery of a gas-rich galaxy in COSMOS

The broad spectral bandwidth at mm and cm-wavelengths provided by the recent upgrades to the Karl G. Jansky Very Large Array (VLA) has made it possible to conduct unbiased searches for molecular CO line emission at redshifts, z > 1.31. We present the discovery of a gas-rich, star-forming galaxy at z = 2.48, through the detection of CO(1-0) line emission in the COLDz survey, through a sensitive, Ka-band (31 to 39 GHz) VLA survey of a 6.5 square arcminute region of the COSMOS field. We argue that the broad line (FWHM ~570 +/- 80 km/s) is most likely to be CO(1-0) at z=2.48, as the integrated emission is spatially coincident with an infrared-detected galaxy with a photometric redshift estimate of z = 3.2 +/- 0.4. The CO(1-0) line luminosity is L'_CO = (2.2 +/- 0.3) x 10^{10} K km/s pc^2, suggesting a cold molecular gas mass of M_gas ~ (2 - 8)x10^{10}M_solar depending on the assumed value of the molecular gas mass to CO luminosity ratio alpha_CO. The estimated infrared luminosity from the (rest-frame) far-infrared spectral energy distribution (SED) is L_IR = 2.5x10^{12} L_solar and the star-formation rate is ~250 M_solar/yr, with the SED shape indicating substantial dust obscuration of the stellar light. The infrared to CO line luminosity ratio is ~114+/-19 L_solar/(K km/s pc^2), similar to galaxies with similar SFRs selected at UV/optical to radio wavelengths. This discovery confirms the potential for molecular emission line surveys as a route to study populations of gas-rich galaxies in the future

Microalgae hydrolysates as functional ingredients

Microalgae have been used in food and cosmetic industries due to their richness in compounds with high biological value, such as proteins, essential amino acids, vitamins and minerals [1]. Several microalgae contain high protein content, similar to other common protein sources such as meat and soybean [1], making them a promising source of bioactive peptides. Bioactive peptides are inert inside proteins but can show several interesting properties when isolated [2]. Antioxidant, antihypertensive, antidiabetic, anticancer, anti-inflammatory and anti-aging are some properties that can be found described in bioactive peptides. Bioactive peptides may be more easily absorbed by the gastrointestinal tract than the intact protein, which allied with their potential bioactivities make them interesting for the development of functional foods, with health benefits for the consumer. Hypertension is one of the main causes of cardiovascular diseases, which can lead to heart attack or stroke. Angiotensin-converting enzyme (ACE) is involved in blood pressure regulation, thus inhibiting it can help to control high blood pressure. Thus, this research aimed to produce water soluble hydrolysates rich in proteins and bioactive peptides, with antioxidant and anti-hypertensive potential, from the five microalgae species Chlorella vulgaris, Nannochloropsis oceanica, Tetraselmis sp., Scenedesmus obliquus and Phaeodactylum tricornutum. The five microalgae species were submitted to an enzymatic hydrolysis (one of the most described methods for producing bioactive peptides) with a cellulase and a subtilisin protease, using previously optimized methods. Prior to the enzymatic hydrolysis, C. vulgaris was submitted to an acid hydrolysis, using a weak and food-grade acid. The anti-hypertensive potential was evaluated by the hydrolysate’s ability of inhibiting ACE. Previous studies [3] showed that C. vulgaris and S. obliquus hydrolysates stood out with the higher antioxidant potential. All the hydrolysates demonstrated anti-hypertensive potential by showing an IC50 lower than 500 μg protein/mL for ACE inhibition (Table 1). Thus, production of peptide hydrolysates from microalgae may represent an interesting approach for the development of sustainable, natural functional ingredients to be used to prevent hypertension on the consumers by incorporating it in food matrices.In conclusion, the enzymatic hydrolysis of microalgae allowed to produce hydrolysates with antioxidant and anti-hypertensive potential. Further studies should be done to confirm the anti-hypertensive ability after the gastrointestinal digestion of the hydrolysates. If the bioactivity is maintained, these hydrolysates may be incorporated in food matrices as functional ingredients, contributing to the development of functional foods with antioxidant and anti-hypertensive benefits for the consumers.info:eu-repo/semantics/publishedVersio