Dusty Sources at the Galactic Center: The N- and Q-band view with VISIR

We present mid-infrared N- and Q-band photometry of the Galactic Center from images obtained with the mid-infrared camera VISIR at the ESO VLT in May 2004. The high resolution and sensitivity possible with VISIR enables us to investigate a total of over 60 point-like sources, an unprecedented number for the Galactic Center at these wavelengths. Combining these data with previous results at shorter wavelengths (Viehmann et al. 2005) enables us to construct SEDs covering the H- to Q-band regions of the spectrum, i.e. 1.6 to 19.5 $\mu$m. We find that the SEDs of certain types of Galactic Center sources show characteristic features. We can clearly distinguish between luminous Northern Arm bow-shock sources, lower luminosity bow-shock sources, hot stars, and cool stars. This characterization may help clarify the status of presently unclassified sources.Comment: 18 pages, 4 figures, 1 table, accepted for publication in the Astrophysical Journa

Respostas das plantas após diferentes distúrbios no Pantanal: estudo de caso de algumas forrageiras.

O conhecimento sobre a resposta das forrageiras aos distúrbios antrópicos e naturais é fundamental para auxiliar os tomadores de decisão na avaliação da condição de conservação e tendência das pastagens nativas ou no desenvolvimento de estratégias adequadas de manejo adaptativas. Este estudo teve como objetivo avaliar a resposta de algumas forrageiras nativas em relação a diferentes distúrbios antrópicos (pastejo e fogo) e naturais (seca e inundação) no Pantanal. Dentre as diversas espécies de plantas do Pantanal, foram escolhidas oito gramíneas e quatro espécies herbáceo-arbustivas. A resposta das plantas ao distúrbio foi classificada como: ?aumenta?, ?diminui? e/ou ?invade?. Observou-se que muitas das espécies podem apresentar aumento ou diminuição quando submetida ao mesmo distúrbio, pois a resposta depende da intensidade e duração do distúrbio, história da dinâmica da vegetação do local, época, ambiente e regime climático. Trabalhos desta natureza devem ser intensificados no Pantanal, envolvendo um maior número de espécies e distúrbios, de preferência com a utilização de parcelas fixas, juntamente com a participação da comunidade local. The knowledge of forage response following anthropogenic and natural disturbance is essential to make decisions making assess of rangeland conservation conditions and trends, or for the development of sound management strategies. The objective of this study was to evaluate the response of some native forage following anthropogenic disturbance (grazing and fire) and natural disturbance (drought and flood) in the Pantanal. Eight grasses and four shrub-herb were selected for this study. Plant response was classified as ?decreaser?, ?increaser? and/or ?invader? species. It was observed that several forages species can to increase or decrease following the same disturbances depending of the frequency, intensity and duration of the disturbance, history of the vegetation dynamic in the area, season, environment and climatical regime. Studies of this type should be intensified in the Pantanal and involve other plants species and disturbance, use fix plots and encourage the participation of the local community

Nutrição mineral de bovinos de corte do Pantanal Mato-Grossense: 2. Micronutrientes na Nhecolandia (Parte Central).

Realatam-se resultados de analise de solos, agua, e gramineas nativas, coletadas em 1979, maio/80 e ago/80, e de figado de bovinos, nessas epocas e em fev/80, na sub-regiao de Nhecolandia, do Pantanal Mato-Grossense. Solos e gramineas foram coletados em cino unidades de paisagem : mata, cerrado, caronal, campo limpo e lagoa. Os resultados sugerem a possibilidade de ocorrencia de toxidez de ferro e manganes, durante /apos o periodo de inundacao, e de deficiencias de cobre e zinco, em determinadas epocas, na sub-regiao abrangida

Adaptive phenotypic plasticity of the native forage grass Paspalum fasciculatum: a trait relevant to climatic changes in wetlands.

This study has been conducted to detect natural forage species having adaptive phenotypic plasticity in wetlands to withstand extreme conditions in drought/flooding cycles.(Embrapa Gado de Corte. Documentos, 216). Coordenador Roberto Giolo de Almeida. II SIGEE. Disponível em: . Acesso em: 01 dez. 2016

Flora da fazenda Nhumirim, Nhecolandia, Pantanal: relacao preliminar.

Com o objetivo de contribuir ao conhecimento da flora do Pantanal, ainda pouco conhecida, e para servir de base a estudos ecologicos fez-se a relacao preliminar da fazenda Nhumirim, considerada representativa da Nhecolandia em termos de solo (arenoso) e flora. As plantas arroladas pertencem a 606 especies, 377 generos e 116 familias. As familias mais numerosas sao: Gramineae (91 especies), Leguminosae (85), Compositae (28), Euphorbiaceae (26) e Cyperaceae (25). Os generos mais representados sao: Cassia (senso amplo), Paspalum, Panicum, Aeschynomene, Axonopus, Croton, Desmodium, Digitaria, Eleocharis, Eupatorium, Ludwigia, Polygala e Tabebuia. Cerca de 12% sao ruderais.bitstream/item/41132/1/PA05.pd

Mid-infrared interferometry with K band fringe-tracking I. The VLTI MIDI+FSU experiment

Context: A turbulent atmosphere causes atmospheric piston variations leading to rapid changes in the optical path difference of an interferometer, which causes correlated flux losses. This leads to decreased sensitivity and accuracy in the correlated flux measurement. Aims: To stabilize the N band interferometric signal in MIDI (MID-infrared Interferometric instrument), we use an external fringe tracker working in K band, the so-called FSU-A (fringe sensor unit) of the PRIMA (Phase-Referenced Imaging and Micro-arcsecond Astrometry) facility at VLTI. We present measurements obtained using the newly commissioned and publicly offered MIDI+FSU-A mode. A first characterization of the fringe-tracking performance and resulting gains in the N band are presented. In addition, we demonstrate the possibility of using the FSU-A to measure visibilities in the K band. Methods: We analyzed FSU-A fringe track data of 43 individual observations covering different baselines and object K band magnitudes with respect to the fringe-tracking performance. The N band group delay and phase delay values could be predicted by computing the relative change in the differential water vapor column density from FSU-A data. Visibility measurements in the K band were carried out using a scanning mode of the FSU-A. Results: Using the FSU-A K band group delay and phase delay measurements, we were able to predict the corresponding N band values with high accuracy with residuals of less than 1 micrometer. This allows the coherent integration of the MIDI fringes of faint or resolved N band targets, respectively. With that method we could decrease the detection limit of correlated fluxes of MIDI down to 0.5 Jy (vs. 5 Jy without FSU-A) and 0.05 Jy (vs. 0.2 Jy without FSU-A) using the ATs and UTs, respectively. The K band visibilities could be measured with a precision down to ~2%.Comment: 11 pages, 13 figures, Accepted for publication in A&

High visitation rate of oil bees may increase pollination efficiency of Couepia uiti in Pantanal wetland

International audienceAbstractPollen transfer to the stigma is the primary mechanism of sexual reproduction in plants. Among bee species that act as pollen vectors and pollinators, attributes such as floral visitation rate, synchrony with the receptive phase of the flower, compatibility between flower shape and foraging behavior, and morphological traits are often used to infer pollination efficiency. Herein, we evaluate visitation frequency and behavior of bee species on Couepia uiti (Chrysobalanaceae) flowers in the southern Pantanal, Brazil. Additionally, after experimental manipulation of flower visitation and by accompanying pollen tube growth in the pistil after one single visit to the flowers, we were able to pinpoint the roles of Centris spilopoda and Apis mellifera on the pollination of C. uiti. Centris spilopoda was the most important pollinator of C. uiti in the study area. In fact, we found that this oil bee might enhance plant reproductive success by almost 40% after a single visit. In addition to its high abundance, the efficiency of C. spilopoda as pollinator may be explained by its tight synchrony with pollen liberation and stigmatic receptivity of flowers of C. uiti

NACO/SAM observations of sources at the Galactic Center

Sparse aperture masking (SAM) interferometry combined with Adaptive Optics (AO) is a technique that is uniquely suited to investigate structures near the diffraction limit of large telescopes. The strengths of the technique are a robust calibration of the Point Spread Function (PSF) while maintaining a relatively high dynamic range. We used SAM+AO observations to investigate the circumstellar environment of several bright sources with infrared excess in the central parsec of the Galaxy. For our observations, unstable atmospheric conditions as well as significant residuals after the background subtraction presented serious problems for the standard approach of calibrating SAM data via interspersed observations of reference stars. We circumvented these difficulties by constructing a synthesized calibrator directly from sources within the field-of-view. When observing crowded fields, this novel method can boost the efficiency of SAM observations because it renders interspersed calibrator observations unnecessary. Here, we presented the first NaCo/SAM images reconstructed using this method.Comment: 8 pages, 10 figures, proceedings of the conference "Astrophysics at High Angular Resolution" (AHAR-2011

Identificação preliminar de grupos funcionais em pastagens nativas no Pantanal.

As pastagens nativas do Pantanal são dinâmicas, principalmente devido às inundações periódicas. O conhecimento sobre os grupos funcionais dos estados de transição dessas comunidades é de extrema importância no manejo para resiliência do ecossistema. Este artigo objetivou identificar grupos funcionais de plantas em uma borda de baía, influenciada por inundação e superpastejo, de bovinos ao longo do tempo. O trabalho foi desenvolvido na borda de uma lagoa superpastejada na fazenda Nhumirim, sub-região da Nhecolândia, Pantanal, no período de setembro 2007 a março 2010