The Chandra Dust Scattering Halo of Galactic Center transient Swift J174540.7-290015

We report the detection of a dust scattering halo around a recently discovered X-ray transient, Swift J174540.7-290015, which in early February of 2016 underwent one of the brightest outbursts (F_X ~ 5e-10 erg/cm^2/s) observed from a compact object in the Galactic Center field. We analyze four Chandra images that were taken as follow-up observations to Swift discoveries of new Galactic Center transients. After adjusting our spectral extraction for the effects of detector pileup, we construct a point spread function for each observation and compare it to the GC field before the outburst. We find residual surface brightness around Swift J174540.7-290015, which has a shape and temporal evolution consistent with the behavior expected from X-rays scattered by foreground dust. We examine the spectral properties of the source, which shows evidence that the object transitioned from a soft to hard spectral state as it faded below L_X ~ 1e36 erg/s. This behavior is consistent with the hypothesis that the object is a low mass X-ray binary in the Galactic Center.Comment: Accepted for publication in Ap

Contribuições do núcleo interinstitucional de agroecologia de Jaguariúna/SP em processos participativos de desenvolvimento rural sustentável.

Resumo: Neste relato apresentamos a experiência da construção de conhecimento agroecológico, desenvolvida na Embrapa Meio Ambiente, Jaguariúna-SP, realizada a partir de 2008. O trabalho contempla a criação e o desenvolvimento de um Núcleo de Agroecologia, interinstitucional e transdiciplinar, composto por pesquisadores, técnicos e agricultores. O objetivo do núcleo é promover, de forma participativa, ações para a evolução do processo de transição agroecológica regional e a construção do conhecimento agroecológico, a partir da identificação das questões limitantes do processo e da integração entre agentes de desenvolvimento regional e agricultores. Os membros do núcleo interinstitucional gerenciam uma área demonstrativa, denominada Sítio Agroecológico, utilizada para demonstrar concretamente conceitos e conhecimentos dos processos ecológicos nos sistemas produtivos, pela implantação, manutenção e monitoramento de unidades de observação. O Sítio configura-se como um elemento integrador do núcleo inteinstitucional, já que ao promover a troca de experiências entre os membros a partir do exercício prático e presencial de atividades em campo

Understanding the impact of line-of-sight in the ergodic spectral efficiency of cellular networks

In this paper we investigate the impact of lineof-sight (LoS) condition in the ergodic spectral efficiency of cellular networks. To achieve this goal, we have considered the kappa-mu shadowed model, which is a general model that provides an excellent fit to a wide set of propagation conditions. To overcome the mathematical complexity of the analysis, we have split the analysis between large and small-scale effects. Building on the proposed framework, we study a number of scenarios that range from heavily-fluctuating LoS to deterministic-LoS. Finally, we shed light on the interplay between fading severity and spectral efficiency by means of the amount of fading.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

A gradient-forming MipZ protein mediating the control of cell division in the magnetotactic bacterium Magnetospirillum gryphiswaldense

Cell division needs to be tightly regulated and closely coordinated with other cellular processes to ensure the generation of fully viable offspring. Here, we investigate division site placement by the cell division regulator MipZ in the alphaproteobacterium Magnetospirillum gryphiswaldense, a species that forms linear chains of magnetosomes to navigate within the geomagnetic field. We show that M. gryphiswaldense contains two MipZ homologs, termed MipZ1 and MipZ2. MipZ2 localizes to the division site, but its absence does not cause any obvious phenotype. MipZ1, by contrast, forms a dynamic bipolar gradient, and its deletion or overproduction cause cell filamentation, suggesting an important role in cell division. The monomeric form of MipZ1 interacts with the chromosome partitioning protein ParB, whereas its ATP-dependent dimeric form shows non-specific DNA-binding activity. Notably, both the dimeric and, to a lesser extent, the monomeric form inhibit FtsZ polymerization in vitro. MipZ1 thus represents a canonical gradient-forming MipZ homolog that critically contributes to the spatiotemporal control of FtsZ ring formation. Collectively, our findings add to the view that the regulatory role of MipZ proteins in cell division is conserved among many alphaproteobacteria. However, their number and biochemical properties may have adapted to the specific needs of the host organism

Comparison of Brans Promethee multicriteria decision method and Promethee modified by authors for the optimization of an erosion control integral plan in Chaco area in Salta province (Argentine)

Chaco area is situated in the Province of Salta at North West of Argentine. The desertification is a big problem. In order to mitigate the problem it is necessary to take into account not only pedologic criteria but the economical, environmental, cultural and sociological criteria. Six sub zones have been established following previous studies. Eight criteria and six alternatives have been introduced in the model. Following the results of the study carried out by a collaborative project between UPM and UCS financed by AECID (1) were established several initial matrix. Brans Promethee multicriteria decision method (MCDM) was applied and the authors modified that method introducing weights like in Electre metho

The advent of organic farming models: analysis of the current situation and perspectives in Brazil.

This text analyses the development of organic farming in Brazil. It shows the great variability of social models of organic production recognised by Brazilian Law: organic, agroecological, ecological or biodynamic agriculture, permaculture etc.. It depicts how the political and social concerns in the spheres of family farming and environment caused the reorganisation of production systems, in the agricultural practices and n the new relationships with the market and with natural resources. Based on interviews with farmers and stakeholders involved in the development of various organic systems, we qualified the related models of production as well as the related social and cultural values. We also present some aspects of the historical roots of this agroecological movement and the way family farmers adapt to the new challenges of ecological production

Processos participativos e o desenvolvimento rural referenciado na agroecologia.

O processo de geração, aprendizagem e compartilhamento de conhecimentos, realizado no cotidiano das instituições de ensino em Ciências Agrárias, de pesquisa agropecuária e de extensão rural, de modo majoritário é condicionado por saberes que valorizam essencialmente aspectos relacionados à produtividade agrícola. Esse viés dominante orienta fortemente as tomadas de decisões quanto às tecnologias a serem adotadas no meio rural. De modo corrente, os objetos de estudo, os métodos de análise, de interpretação, de avaliação de dados e de intervenção, são definidos com base nas formações acadêmicas presentes nos quadros dessas instituições, destacadamente referenciadas em especializações disciplinares das Ciências Agrárias. Esses conhecimentos especializados são extremamente importantes à agricultura nacional, mas oferecem sérios riscos ao privilegiar uma visão unidirecional de problemas multifatoriais relacionados a questões agrícolas, agrárias, econômicas, sociais, culturais, éticas e ambientais. Diante das consequências do modelo de geração e adoção de tecnologia