Electronic structure of nuclear-spin-polarization-induced quantum dots

We study a system in which electrons in a two-dimensional electron gas are confined by a nonhomogeneous nuclear spin polarization. The system consists of a heterostructure that has non-zero nuclei spins. We show that in this system electrons can be confined into a dot region through a local nuclear spin polarization. The nuclear-spin-polarization-induced quantum dot has interesting properties indicating that electron energy levels are time-dependent because of the nuclear spin relaxation and diffusion processes. Electron confining potential is a solution of diffusion equation with relaxation. Experimental investigations of the time-dependence of electron energy levels will result in more information about nuclear spin interactions in solids

Modulation of the oxidative stress in malaria infection by clotrimazole

Antimycotic clotrimazole (CTZ) has demonstrated remarkable activity against Plasmodium falciparum in vitro and in vivo. Hemoglobin degradation by Plasmodium parasites makes amino acids available for protein synthesis, inducing oxidative stress in infected cells and producing free heme. These events represent biochemical targets for potential antimalarials. In this study, we have tested the ability of CTZ to modify the oxidative status in Plasmodium berghei-infected erythrocytes. After hemolysis, activities of superoxide dismutase (SOD), catalase (CAT), glutathione cycle and NADPH+H+-producing dehydrogenases were investigated using UV-visible spectrophotometry. Thiobarbituric acid reactive substances (TBARS) were evaluated as a marker of lipid damage. Results showed that CTZ significantly decreased the overall activity of 6-phosphagluconate dehydrogenase (6PGD) compared to infected and non-treated cells; consequently, the glutathione cycle was inhibited, leaving the parasite vulnerable to the oxidative stress originating from hemoglobin degradation. As a compensatory response, CTZ prevented some loss of SOD and CAT activities in infected cells. The infection triggered lipid peroxidation in erythrocytes, which was decreased by CTZ. These results suggest the presence of a redox unbalance in cells treated with CTZ, discussing a possible effect of this compound disturbing the oxidative status in a Plasmodium berghei-infection.O antifúngico clotrimazol (CTZ) tem demonstrado notável atividade contra Plasmodium falciparum. A degradação da hemoglobina por Plasmodium para a obtenção dos aminoácidos necessários à síntese protéica induz estresse oxidativo em eritrócitos devido à liberação de hemos oxidantes. Estes eventos representam alvos bioquímicos para a produção de antimaláricos potenciais. Neste estudo, testamos a capacidade do CTZ para modificar o estado oxidativo em eritrócitos infectados com Plasmodium berghei. Depois da hemólise, as atividades da superóxido dismutase (SOD), catalase (CAT), desidrogenases produtoras de NADPH+H+ e do ciclo de glutationa (GSH) foram investigados. A produção das espécies reativas ao ácido tiobarbitúrico (TBARS) foi avaliada como marcador de dano lipídico. Os resultados mostraram que o CTZ diminuiu a atividade da 6-fosfogliconato desidrogenase (6PGD), em comparação com eritrócitos infectados e não tratados. Consequentemente, o ciclo da GSH foi inibido, tornando os parasitas vulneráveis ao estresse oxidativo resultante da degradação da hemoglobina. Como resposta compensatória, CTZ impediu a perda de atividade da SOD e CAT nas células infectadas. A infecção induz peroxidação lipídica nos eritrócitos, sendo esta diminuída pelo CTZ. Estes resultados sugerem a existência de desequilíbrio redox nas células tratadas com CTZ, interferindo, assim, com o estado oxidativo verificado durante a infecção malárica

Integrating Remotely Sensed Imagery and Existing Multiscale Field Data to Derive Rangeland Indicators: Application of Bayesian Additive Regression Trees

Remotely sensed imagery at multiple spatial scales is used increasingly in conjunction with field data to estimate rangeland indicators (e.g., vegetation cover) and meet the growing need for landscape-scale monitoring and assessment of rangelands. Remote sensing studies that produce rangeland indicators often require intensive and costly field-data collection efforts to produce accurate model predictions. Existing monitoring data, such as those collected by the Bureau of Land Management's Assessment, Inventory, and Monitoring (AIM) program, are potentially useful sources of field data in remote sensing modeling studies. Given their data-hungry nature, common regression tree - based modeling approaches may be inadequate for reliably predicting rangeland indicators with the smaller sample sizes of AIM data than typically used for remote sensing studies. Current literature suggests that Bayesian models, such as Bayesian additive regression trees (BART), may provide a suitable alternative to traditional regression tree - based modeling approaches to overcome the sample size limitation of the AIM data. In this study, we used 182 AIM field plots together with both high (RapidEye) and moderate (Landsat OLI) spatial resolution satellite imagery to predict bare ground and bare soil, total foliar, herbaceous, woody, and shrub cover indicators on rangelands in a 14 625-km2 area of northeastern California. We demonstrate that a BART model performed similarly to other regression tree approaches when field data and high spatial resolution imagery predictions were combined to predict indicator values using the medium spatial resolution Landsat image. The BART models also provided spatially explicit uncertainty estimates, which allow land managers to more carefully evaluate indicator predictions and to identify areas where future field data collection might be most useful. This study demonstrates that existing field data and freely available, remotely sensed imagery can be integrated to produce spatially explicit and continuous surface estimates of rangeland indicators across entire landscapes. © Published by Elsevier Inc. on behalf of The Society for Range Management.The Rangeland Ecology & Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information

The Color of 4 Vesta and Lithology Diversity: First Results from Dawn Survey Orbit

The FC cameras onboard the Dawn spacecraft are expected to map the asteroid 4 Vesta in seven different colors from Survey Orbit in August 2011. We will present the first immediate results of the spectral mapping of the visible surface from FC images along with their association with surface compositional units. The first medium resolution observations of Vesta have been performed in July 201

The current status and management of South Africa’s chondrichthyan fisheries

Chondrichthyans (sharks, skates, rays and chimaeras) are captured in many marine fisheries. Management and research efforts directed at chondrichthyan fishing are often neglected because of low product value, taxonomic uncertainty, low capture rates, and harvesting by multiple fisheries. In South Africa’s diverse fishery sectors, which include artisanal as well as highly industrialised fisheries, 99 (49%) of 204 chondrichthyan species that occur in southern Africa are targeted regularly or taken as bycatch. Total reported dressed catch for 2010, 2011 and 2012 was estimated to be 3 375 t, 3 241 t and 2 527 t, respectively. Two-thirds of the reported catch was bycatch. Regulations aimed at limiting chondrichthyan catches, coupled with species-specific permit conditions, currently exist in the following fisheries: demersal shark longline, pelagic longline, recreational line, and beach-seine and gillnet. Limited management measures are currently in place for chondrichthyans captured in other South African fisheries. Catch and effort dataseries suitable for stock assessments exist for fewer than 10 species. Stock assessments have been attempted for five shark species: soupfin Galeorhinus galeus, smoothhound Mustelus mustelus, white Carcharodon carcharias, spotted ragged-tooth Carcharias taurus, and spotted gully Triakis megalopterus. Fishery-independent surveys and fishery observer data, which can be used as a measure of relative abundance, exist for 67 species. Compared with most developing countries, South African shark fishing is relatively well controlled and managed. As elsewhere, incidental capture and bycatch remain challenges to the appropriate management of shark species. In 2013, South Africa’s National Plan of Action for the Conservation and Management of Sharks (NPOA-Sharks) was published. Implementation of the NPOA-Sharks should help to improve chondrichthyan management in the near future.Keywords: bycatch, fisheries management, shark fisheries, shark trade, stock assessmen