Deep GMRT radio observations and a multi-wavelength study of the region around HESS J1858+020

Context. There are a number of very high energy sources in the Galaxy that remain unidentified. Multi-wavelength and variability studies, and catalogue searches, are powerful tools to identify the physical counterpart, given the uncertainty in the source location and extension. Aims. This work carries out a thorough multi-wavelength study of the unidentified, very high energy source HESS J1858+020 and its environs. Methods. We have performed Giant Metrewave Radio Telescope observations at 610 MHz and 1.4 GHz to obtain a deep, low-frequency radio image of the region surrounding HESS J1858+020. We analysed archival radio, infrared, and X-ray data as well. This observational information, combined with molecular data, catalogue sources, and a nearby Fermi gamma-ray detection of unidentified origin, are combined to explore possible counterparts to the very high energy source. Results. We provide with a deep radio image of a supernova remnant that might be related to the GeV and TeV emission in the region. We confirm the presence of an H ii region next to the supernova remnant and coincident with molecular emission. A potential region of star formation is also identified. We identify several radio and X-ray sources in the surroundings. Some of these sources are known planetary nebulae, whereas others may be non-thermal extended emitters and embedded young stellar objects. Three old, background Galactic pulsars also neighbour HESS J1858+020 along the line of sight. Conclusions. The region surrounding HESS J1858+020 is rich in molecular structures and non-thermal objects that may potentially be linked to this unidentified very high energy source. In particular, a supernova remnant interacting with nearby molecular clouds may be a good candidate, but a star forming region, or a non-thermal radio source of yet unclear nature, may also be behind the gamma-ray source. The neighbouring pulsars, despite being old and distant, cannot be discarded as candidates. Further observational studies are needed, however, to narrow the search for a counterpart to the HESS source.

CARCINOMA BRONQUÍOLO-ALVEOLAR: ASPECTOS NA TOMOGRAFIA COMPUTADORIZADA DE ALTA RESOLUÇÃO

O carcinoma bronquíolo-alveolar é um tipo de carcinoma broncogênico de crescimento insidioso, que surge nas paredes das vias aéreas distais e se dissemina utilizando o septo alveolar como um estroma, preservando a arquitetura pulmonar. Neste trabalho foram analisadas as tomografias computadorizadas de alta resolução de 17 pacientes com carcinoma bronquíolo-alveolar. Ao contrário do relatado na literatura, foram observados predomínio no sexo masculino (71%) e maior freqüência da associação das formas de consolidação e multinodular (53%) em relação à forma nodular solitária (12%), multinodular (12%) e de consolidação (23%). Os aspectos mais encontrados foram: áreas de consolidação (76%), broncograma aéreo (71%), áreas de baixa atenuação provavelmente devidas à presença de muco (60%), espessamento de septos interlobulares, opacidades em vidro fosco e nódulos confluentes (54% cada), e pavimentação em mosaico (36%). Os nódulos cavitados, a atelectasia, o sinal do halo e o aspecto de "árvore em brotamento" foram observados em apenas um caso cada.

Optical spectroscopy of microquasar candidates at low Galactic latitudes

We report optical spectroscopic observations of a sample of 6 low-galactic latitude microquasar candidates selected by cross-identification of X-ray and radio point source catalogs for |b|<5 degrees. Two objects resulted to be of clear extragalactic origin, as an obvious cosmologic redshift has been measured from their emission lines. For the rest, none exhibits a clear stellar-like spectrum as would be expected for genuine Galactic microquasars. Their featureless spectra are consistent with being extragalactic in origin although two of them could be also highly reddened stars. The apparent non-confirmation of our candidates suggests that the population of persistent microquasar systems in the Galaxy is more rare than previously believed. If none of them is galactic, the upper limit to the space density of new Cygnus X-3-like microquasars within 15 kpc would be 1.1\times10^{-12} per cubic pc. A similar upper limit for new LS 5039-like systems within 4 kpc is estimated to be 5.6\times10^{-11} per cubic pc.

EVN+MERLIN observations of microquasar candidates at low galactic latitudes

In an attempt to increase the number of known microquasars, Paredes et al. (2002) have presented a long-term project focused on the search for new objects of this type. They performed a cross-identification between X-ray and radio catalogs under very restrictive selection criteria for sources with |b|<5 degrees, and obtained a sample of 13 radio-emitting X-ray sources. Follow-up observations of 6 of these sources with the VLA provided accurate coordinates, which were used to discover optical counterparts for all of them. We have observed these six sources with the EVN and MERLIN at 5 GHz. Five of the six objects have been detected and imaged, presenting different morphologies: one source has a two-sided jet, three sources have one-sided jets, and one source is compact. With all the presently available information, we conclude that two of the sources are promising microquasar candidates in our Galaxy.

High mass microquasars and low latitude gamma-ray sources

Population studies of unidentified EGRET sources suggest that there exist at least three different populations of galactic gamma-ray sources. One of these populations is formed by young objects distributed along the galactic plane with a strong concentration toward the inner spiral arms of the Galaxy. Variability, spectral and correlation analysis indicate that this population is not homogeneous. In particular, there is a subgroup of sources that display clear variability in their gamma-ray fluxes on timescales from days to months. Following the proposal by Kaufman Bernad\'o et al. (2002), we suggest that this group of sources might be high-mass microquasars, i.e. accreting black holes or neutron stars with relativistic jets and early-type stellar companions. We present detailed inhomogeneous models for the gamma-ray emission of these systems that include both external and synchrotron self-Compton interactions. We have included effects of interactions between the jet and all external photon fields to which it is exposed: companion star, accretion disk, and hot corona. We make broadband calculations to predict the spectral energy distribution of these objects from radio up to GeV energies. The results and predictions can be tested by present and future gamma-ray instruments like INTEGRAL, AGILE, and GLAST.

Tomografia computadorizada na avaliação da aspergilose pulmonar angioinvasiva em pacientes com leucemia aguda

OBJETIVO: O objetivo deste trabalho foi avaliar os principais achados na tomografia computadorizada de pacientes portadores de leucemia aguda complicada com aspergilose pulmonar angioinvasiva. MATERIAIS E MÉTODOS: Foram estudadas, retrospectivamente, as tomografias computadorizadas de 19 pacientes, avaliando-se a presença de consolidações, nódulos e massas, com ou sem sinal do halo, escavação e sinal do crescente aéreo. RESULTADOS: Áreas de consolidação foram o achado mais comum, ocorrendo em 12 dos 19 casos. A maioria delas apresentou o sinal do halo, enquanto escavação foi encontrada em 5 dos 12 casos com consolidações, sendo um deles com sinal do crescente aéreo. Nódulos e massas ocorreram em, respectivamente, seis e quatro casos, a maioria com sinal do halo. Escavação foi encontrada em apenas um caso de massa. Outros achados observados foram pavimentação em mosaico (dois casos), áreas de vidro fosco esparsas (três casos) e envolvimento pleural (sete casos), sob a forma de derrame ou espessamento. CONCLUSÃO: Áreas de consolidação, massas ou nódulo, mesmo solitário, com sinal do halo, quando vistos na tomografia computadorizada em um contexto clínico apropriado, são altamente sugestivos de aspergilose angioinvasiva.

Avaliação da concordância interobservador na análise da tomografia computadorizada sem contraste no diagnóstico da urolitíase em pacientes com cólica renal aguda

OBJETIVO: Avaliar a reprodutibilidade da tomografia computadorizada sem contraste na avaliação da litíase ureteral e os sinais secundários de obstrução do sistema coletor em pacientes com cólica renal aguda. MATERIAIS E MÉTODOS: Estudo prospectivo de 52 pacientes com diagnóstico clínico de cólica renal aguda submetidos a exame de tomografia computadorizada de abdome sem contraste. Os exames foram realizados com técnica helicoidal e posteriormente analisados por três observadores independentes, com a concordância interobservador avaliada pelo método estatístico kappa (kapa). Foram analisados os parâmetros: a) presença, localização e mensuração dos cálculos ureterais; b) dilatação do sistema coletor intra-renal; c) heterogeneidade da gordura perirrenal; d) dilatação ureteral; e) edema da parede ureteral (sinal do halo). RESULTADOS: Foram encontrados 40 cálculos ureterais na tomografia computadorizada (77%). A concordância interobservador para a identificação do cálculo ureteral e da dilatação ureteral foi quase perfeita (kapa = 0,89 e kapa = 0,87, respectivamente), substancial para dilatação do sistema coletor intra-renal (kapa = 0,77) e moderada para heterogeneidade da gordura perirrenal e para edema da parede ureteral (kapa = 0,55 e kapa = 0,56, respectivamente). CONCLUSÃO: A tomografia computadorizada de abdome sem contraste apresenta elevada reprodutibilidade na avaliação da litíase ureteral e dos sinais secundários de obstrução do sistema coletor.

Microquasar models for 3EG J1828+0142 and 3EG J1735-1500

Microquasars are promising candidates to emit high-energy gamma-rays. Moreover, statistical studies show that variable EGRET sources at low galactic latitudes could be associated with the inner spiral arms. The variable nature and the location in the Galaxy of the high-mass microquasars, concentrated in the galactic plane and within 55 degrees from the galactic center, give to these objects the status of likely counterparts of the variable low-latitude EGRET sources. We consider in this work the two most variable EGRET sources at low-latitudes: 3EG J1828+0142 and 3EG J1735-1500, proposing a microquasar model to explain the EGRET data in consistency with the observations at lower energies (from radio frequencies to soft gamma-rays) within the EGRET error box.

Optimized dark matter searches in deep observations of Segue 1 with MAGIC

We present the results of stereoscopic observations of the satellite galaxy Segue 1 with the MAGIC Telescopes, carried out between 2011 and 2013. With almost 160 hours of good-quality data, this is the deepest observational campaign on any dwarf galaxy performed so far in the very high energy range of the electromagnetic spectrum. We search this large data sample for signals of dark matter particles in the mass range between 100 GeV and 20 TeV. For this we use the full likelihood analysis method, which provides optimal sensitivity to characteristic gamma-ray spectral features, like those expected from dark matter annihilation or decay. In particular, we focus our search on gamma-rays produced from different final state Standard Model particles, annihilation with internal bremsstrahlung, monochromatic lines and box-shaped signals. Our results represent the most stringent constraints to the annihilation cross-section or decay lifetime obtained from observations of satellite galaxies, for masses above few hundred GeV. In particular, our strongest limit (95% confidence level) corresponds to a ~ 500 GeV dark matter particle annihilating into τ+τ−, and is of order langleσannvrangle simeq 1.2 × 10−24 cm3 s−1 a factor ~ 40 above the langleσannvrangle simeq thermal value.

Estudo dos ventrículos cerebrais por ultrassonografia, na criança normal, nascida a termo, de 1 a 6 meses

OBJETIVO: Estudo dos ventrículos cerebrais por ultrassonografia, com o objetivo de estabelecer de forma simplificada parâmetros para diagnóstico das dilatações ventriculares leves. MATERIAIS E MÉTODOS: Foram estudadas, prospectivamente, 105 crianças, normais, nascidas a termo, com um total de 181 exames realizados, mensalmente até os 6 meses, através da observação de dados morfológicos e medidas. As medidas efetuadas foram: índice ventrículo/hemisfério, diâmetro anteroposterior do corno anterior e do quarto ventrículo. RESULTADOS: Obtiveram-se média, desviopadrão e percentis de normalidade das medidas estabelecidas, em cada faixa etária. A pesquisa de halo anecoico nos dois terços posteriores do plexo coroide em plano coronal VI, para avaliação dos cornos temporal/posterior, foi ausente, e o terceiro ventrículo mostrou-se como uma fenda anecoica, menor que 1 mm, em plano coronal V em todas as crianças do estudo. CONCLUSÃO: Os achados morfológicos relacionados aos cornos temporal/posterior e ao terceiro ventrículo, associados ao percentil 95 das medidas como limite superior da normalidade, podem ser utilizados para diagnóstico simplificado de dilatações ventriculares leves.

Evolution and Stellar Content of AGN Host Galaxies

In this dissertation, Active Galactic Nuclei (AGN) and their host galaxies are discussed. Together with transitional events, such as supernovae and gamma-ray bursts, AGN are the most energetic phenomena in the Universe. The dominant fraction of their luminosity originates from the center of a galaxy, where accreting gas falls into a supermassive black hole, converting gravitational energy to radiation. AGN have a wide range of observed properties: e.g. in their emission lines, radio emission, and variability. Most likely, these properties depend significantly on their orientation to our line-of-sight, and to unify AGN into physical classes it is crucial to observe their orientation-independent properties, such as the host galaxies. Furthermore, host galaxy studies are essential to understand the formation and co-evolution of galactic bulges and supermassive black holes. In this thesis, the main focus is on observationally characterizing AGN host galaxies using optical and near-infrared imaging and spectroscopy. BL Lac objects are a class of AGN characterized by rapidly variable and polarized continuum emission across the electromagnetic spectrum, and coredominated radio emission. The near-infrared properties of intermediate redshift BL Lac host galaxies are studied in Paper I. They are found to be large elliptical galaxies that are more luminous than their low redshift counterparts suggesting a strong luminosity evolution, and a contribution from a recent star formation episode. To analyze the stellar content of galaxies in more detail multicolor data, especially observations at blue wavelengths, are essential. In Paper III, optical - near-infrared colors and color gradients are derived for low redshift BL Lac host galaxies. They show bluer colors and steeper color gradients than inactive ellipticals which, most likely, are caused by a relatively young stellar population indicating a different evolutionary stage between AGN hosts and inactive ellipticals. In Paper II, near-infrared imaging of intermediate redshift radio-quiet quasar hosts is used to study their luminosity evolution. The hosts are large elliptical galaxies, but they are systematically fainter than the hosts of radio-loud quasars at similar redshifts, suggesting a link between the luminosity of the host galaxies and the radio properties of AGN. In Paper IV, the characteristics of near-infrared stellar absorption features of low redshift radio galaxies are compared with those of inactive early-type galaxies. The comparison suggests that early-type galaxies with AGN are in a different evolutionary stage than their inactive counterparts. Moreover, radio galaxies are found to contain stellar populations containing both old and intermediate age components.

Learning in Digital Media: the legacy of McLuhan and his Impact on Formal Education

This paper describes a bibliographic analysis of the vision of Marshal McLuhan and the vision adopted by diverse current authors regarding the use of new interactive learning technologies. The paper also analyzes the transformation that will have to take place in the formal surroundings of education in order to improve their social function. The main points of view and contributions made by diverse authors are discussed. It is important that all actors involved in the educational process take in consideration these contributions in order to be ready for future changes.

Avaliando a taxa de expansão de lesões de Bipolaris sorokiniana em trigo

Os primeiros sintomas de mancha marrom causada por Bipolaris sorokiniana em trigo (Triticum aestivum) têm início com pequenos pontos negros nas folhas. À medida que se expandem, as lesões adquirem formato oval, com o centro marrom-escuro e halo amarelado. Em condições favoráveis, as lesões coalescem necrosando grandes áreas da folha. O efeito da temperatura na taxa de expansão de lesão de B. sorokiniana foi determinado em oito cultivares de trigo. Imagens digitalizadas das lesões de diferentes cultivares e em distintos regimes de temperatura foram capturadas a intervalos regulares e armazenadas eletronicamente. Um software específico, denominado AreaScan, foi usado para medir a área individual das lesões. A velocidade de expansão de lesão de B. sorokiniana diferiu entre cultivares. A cultivar BR 18 apresentou a taxa de expansão de lesão mais lenta. As cultivares Embrapa 15 e Embrapa 16 apresentaram a taxa mais rápida, enquanto BR 15, BR 23, BR 35, Embrapa 40 e Embrapa 49 apresentaram taxa intermediária. A relação entre a taxa de expansão e a temperatura foi descrita por uma função matemática y=(a+bx)/(1+cx+dx²), onde y é a resposta, x a temperatura, e a,b,c,d parâmetros. O regime de temperatura diurna de 30 °C e noturna de 23 °C foi o mais favorável ao desenvolvimento de lesão de B. sorokiniana. A obtenção de cultivares de trigo com resistência parcial à mancha marrom é estratégico para o estabelecimento da cultura em regiões tropicais e subtropicais. A metodologia usada provou ser uma importante ferramenta na identificação de cultivares de trigo com tais características.

Three new pathogens infecting antilles cherry in the State of Pará

When grown in monoculture, Antilles cherry (Malpighia glabra) plants have been affected by diseases which cause fruits malformation and spotting, reducing their value for market. From 1999 on, three new diseases characterised by leaf spot and fall of leaves have been observed in plantations located in Santa Izabel do Pará and Igarapé Açu counties. After isolation and pathogenicity tests on leaves of Antilles cherry plants, the isolates were identified as Calonectria ilicicola (anamorph: Cylindrocladium parasiticum) which causes large leaf spots reaching up to 7 cm long, brownish in colour, coalescent, scorching large leaf areas and causing 50% of leaf fall; Corynespora cassiicola, which provokes irregularly shaped, necrotic leaf spots with dark brown margins and white centers, surrounded by a yellow halo; and Myrothecium roridum which causes greyish target spots. Corynespora cassiicola has been reported causing leaf spots on different hosts in the Amazon region, while C. cassiicola has been recorded infecting Antilles cherry besides other hosts in the States of Maranhão and Pará.

Agressividade de linhagens de Xanthomonas axonopodis pv. aurantifolii Tipo C em lima ácida 'Galego'

O presente trabalho objetivou gerar informações referentes à agressividade de linhagens de Xanthomonas axonopodis pv. aurantifolii Tipo C(Xaa-C), produtoras (PP) e não produtoras de pigmento (NP) escuro em meio de cultura, comparativamente a X. axonopodis pv. citri Tipo A (Xac) . Os tratamentos foram formados por 14 linhagens, sendo sete de Xaa-C PP, cinco Xaa-C NP, e duas linhagens de Xac. As linhagens foram inoculadas através de ferimentos, em folhas de lima ácida 'Galego' (Citrus aurantifolia Swingle), com agulha previamente mergulhada em uma suspensão de células bacterianas (10(7) UFC/mL). Foram realizadas dez repetições para cada tratamento, representadas por uma planta cada. As plantas foram mantidas em casa de vegetação durante todo o experimento. As linhagens diferiram entre si quanto ao período de incubação, diâmetro e populações bacterianas das lesões e, comparativamente, Xaa-C NP mostraram-se mais agressivas do que Xaa-C PP. Algumas linhagens induziram sintomas que diferiram quanto à presença e extensão de anasarca, halo amarelo e saliência do tecido necrosado.