Analysis of the early-time optical spectra of SN 2011fe in M101

The nearby Type Ia supernova SN 2011fe in M101 (cz=241 km s^-1) provides a unique opportunity to study the early evolution of a "normal" Type Ia supernova, its compositional structure, and its elusive progenitor system. We present 18 high signal-to-noise spectra of SN 2011fe during its first month beginning 1.2 days post-explosion and with an average cadence of 1.8 days. This gives a clear picture of how various line-forming species are distributed within the outer layers of the ejecta, including that of unburned material (C+O). We follow the evolution of C II absorption features until they diminish near maximum light, showing overlapping regions of burned and unburned material between ejection velocities of 10,000 and 16,000 km s^-1. This supports the notion that incomplete burning, in addition to progenitor scenarios, is a relevant source of spectroscopic diversity among SNe Ia. The observed evolution of the highly Doppler-shifted O I 7774 absorption features detected within five days post-explosion indicate the presence of O I with expansion velocities from 11,500 to 21,000 km s^-1. The fact that some O I is present above C II suggests that SN 2011fe may have had an appreciable amount of unburned oxygen within the outer layers of the ejecta.

Learning Extended Tree Augmented Naive Structures

This work proposes an extended version of the well-known tree-augmented naive Bayes (TAN) classifier where the structure learning step is performed without requiring features to be connected to the class. Based on a modification of Edmonds' algorithm, our structure learning procedure explores a superset of the structures that are considered by TAN, yet achieves global optimality of the learning score function in a very efficient way (quadratic in the number of features, the same complexity as learning TANs). We enhance our procedure with a new score function that only takes into account arcs that are relevant to predict the class, as well as an optimization over the equivalent sample size during learning. These ideas may be useful for structure learning of Bayesian networks in general. A range of experiments shows that we obtain models with better prediction accuracy than naive Bayes and TAN, and comparable to the accuracy of the state-of-the-art classifier averaged one-dependence estimator (AODE). We release our implementation of ETAN so that it can be easily installed and run within Weka.

Finding Relevant Tweets

When a user of a microblogging site authors a microblog
post or browses through a microblog post, it provides cues as to what
topic she is interested in at that point in time. Example-based search
that retrieves similar tweets given one exemplary tweet, such as the one
just authored, can help provide the user with relevant content. We investigate
various components of microblog posts, such as the associated
timestamp, author’s social network, and the content of the post, and
develop approaches that harness such factors in finding relevant tweets
given a query tweet. An empirical analysis of such techniques on real
world twitter-data is then presented to quantify the utility of the various
factors in assessing tweet relevance. We observe that content-wise similar
tweets that also contain extra information not already present in the
query, are perceived as useful. We then develop a composite technique
that combines the various approaches by scoring tweets using a dynamic
query-specific linear combination of separate techniques. An empirical
evaluation establishes the effectiveness of the composite technique, and
that it outperforms each of its constituents.

Internet of Things. A proposed secured network topology

The myriad of technologies and protocols working at different layers pose significant security challenges in the upcoming Internet of Things (IoT) paradigm. Security features and needs vary from application to application and it is layer specific. In addition, security has to consider the constraints imposed by energy limited sensor nodes and consider the specific target application in order to provide security at different layers. This paper analyses current standardization efforts and protocols. It proposes a generic secured network topology for IoT and describes the relevant security challenges. Some exploitation examples are also provided.

Laboratory measurements of resistivity in warm dense plasmas relevant to the microphysics of brown dwarfs

Since the observation of the first brown dwarf in 1995, numerous studies have led to a better understanding of the structures of these objects. Here we present a method for studying material resistivity in warm dense plasmas in the laboratory, which we relate to the microphysics of brown dwarfs through viscosity and electron collisions. Here we use X-ray polarimetry to determine the resistivity of a sulphur-doped plastic target heated to Brown Dwarf conditions by an ultra-intense laser. The resistivity is determined by matching the plasma physics model to the atomic physics calculations of the measured large, positive, polarization. The inferred resistivity is larger than predicted using standard resistivity models, suggesting that these commonly used models will not adequately describe the resistivity of warm dense plasma related to the viscosity of brown dwarfs.

Laser-driven x-ray and neutron source development for industrial applications of plasma accelerators

Pulsed beams of energetic x-rays and neutrons from intense laser interactions with solid foils are promising for applications where bright, small emission area sources, capable of multi-modal delivery are ideal. Possible end users of laser-driven multi-modal sources are those requiring advanced non-destructive inspection techniques in industry sectors of high value commerce such as aerospace, nuclear and advanced manufacturing. We report on experimental work that demonstrates multi-modal operation of high power laser-solid interactions for neutron and x-ray beam generation. Measurements and Monte Carlo radiation transport simulations show that neutron yield is increased by a factor ∼2 when a 1 mm copper foil is placed behind a 2 mm lithium foil, compared to using a 2 cm block of lithium only. We explore x-ray generation with a 10 picosecond drive pulse in order to tailor the spectral content for radiography with medium density alloy metals. The impact of using >1 ps pulse duration on laser-accelerated electron beam generation and transport is discussed alongside the optimisation of subsequent bremsstrahlung emission in thin, high atomic number target foils. X-ray spectra are deconvolved from spectrometer measurements and simulation data generated using the GEANT4 Monte Carlo code. We also demonstrate the unique capability of laser-driven x-rays in being able to deliver single pulse high spatial resolution projection imaging of thick metallic objects. Active detector radiographic imaging of industrially relevant sample objects with a 10 ps drive pulse is presented for the first time, demonstrating that features of 200 μm size are resolved when projected at high magnification.

Comunicação pública em territórios rurais – perceções e participação dos atores globais em Avelãs de Cima

Vivemos num mundo cada vez mais globalizado e uma das consequências é a crescente concorrência que existe entre territórios, reforçando-se a necessidade de fazer chegar aos públicos interessados, um conjunto de atributos e diferenciações, suficientemente atrativos e apelativos, para que estes territórios sejam “consumidos”, não só pelo seu reconhecimento temporal, mas também pela forma como ele se comunica. Se até ao momento esta diferenciação era apenas explicitada numa base meramente turística (pelos impactos económicos positivos que normalmente se conseguem), hoje a estratégia deve seguir um plano de marketing capaz de atrair e fixar quer residentes, excursionistas, turistas e investidores, satisfazendo-os. Dos estudos realizados é comumente aceite que o sucesso da execução de um plano de marketing territorial assenta num modelo participativo que promova e antecipe necessidades e desejos dos atores globais e que valide e identifique os pontos fortes, para ajudar a desenvolver (definir e implementar) uma estratégia sustentável, a prazo. Então é relevante chamar ao processo estes atores (públicos e privados, residentes e visitantes) envolvendo-os nesta identificação, comprometendo-os também nos seus resultados.Com este artigo apresenta-se então um estudo de caso aplicado a um território rural, na freguesia de Avelãs de Cima, tendo sido utilizada como metodologia um inquérito por questionário a todos os atores. Enumeram-se os fatores relevantes identificados, assim como os que não se desejam ver aplicados, requisitos evidentes para iniciar uma nova política de comunicação pública. Deste trabalho já resultou uma nova abordagem pelos atores públicos locais, destacando a perspetiva de utilização de sinergias pela integração dos recursos de duas outras freguesias, estando em construção um projeto comum de rotas com base nos atributos dessas localidades.-----We live in an increasingly globalized world and one of the consequences is the increasing competition that exists between areas, reinforcing the need to reach out to stakeholders, a set of attributes and differences sufficiently attractive and appealing, so that these territories are "consumed ", not only by their temporal recognition, but also for how it communicates. If so far this differentiation was only explained in a purely tourist base (by the positive economic impacts that usually can get), today the strategy must follow a marketing plan able to attract and retain residents, hikers, tourists and investors. There are studies where is commonly accepted that the successful implementation of a territorial marketing plan based on a participatory model that promotes and anticipate needs and desires of the global players and validate and identify the strengths, to help develop (define and implement) one sustainable strategy in the long term. So it is relevant to call these actors (public and private, residents and visitors) involving them in this identification and also committing them in their results. With this article we present a case study applied to a rural area in the parish of Avelãs de Cima, having been used a survey methodology for all actors. All the relevant identified factors are listed, as well as those which do not wish to see applied, clear requirements to start a new policy of public communication. This work has resulted in a new approach by local public actors, highlighting the prospect of using synergies by integrating the features of two other parishes, under construction with a common design routes based on attributes of those localities.

Transplant glomerulopathy: clinico-pathologic features

Transplant glomerulopathy is a sign of chronic kidney allograft damage. It has a distinct morphology and is associated with poor allograft survival. We aimed to assess the prevalence and clinic-pathologic features of transplant glomerulopathy, as well as determine the functional and histological implications of its severity. We performed a single-centre retrospective observational study during an eight-year period. Kidney allograft biopsies were diagnosed and scored according to the Banff classification, coupled with immunofluorescence studies. The epidemiology, clinical presentation, outcomes (patient and graft survival) and anti-HLA alloantibodies were evaluated. Transplant glomerulopathy was diagnosed in 60 kidney transplant biopsies performed for clinical reasons in 49 patients with ABO compatible renal transplant and a negative T-cell complement dependent cytotoxicity crossmatch at transplantation. The estimated prevalence of transplant glomerulopathy was 7.4% and its cumulative prevalence increased over time. C4d staining in peritubular capillaries (27.6%) was lower than the frequency of anti-HLA antibodies (72.5%), the majority against both classes I and II. Transplant glomerulopathy was associated with both acute (mainly glomerulitis and peritubular capillaritis) and chronic histologic abnormalities. At diagnosis, 30% had mild, 23.3% moderate and 46.7% severe transplant glomerulopathy. The severity of transplant glomerulopathy was associated with the severity of interstitial fibrosis. Other histological features, as well as clinical manifestations and graft survival, were unrelated to transplant glomerulopathy severity.