HST/STIS Observations of the Optical Counterpart to GRB 970228

We report on observations of the fading optical counterpart of the gamma-ray burst GRB 970228, made on 4~September~1997 using the STIS CCD on the Hubble Space Telescope. The unresolved counterpart is detected at V=28 +/- 0.25, consistent with a continued power-law decline with exponent -1.14 +/- 0.05. No proper motion is detected, in contradiction of some earlier claims. The counterpart is located within, but near the edge of, a faint extended source with diameter ~0."8 and integrated magnitude 25.7 +/- 0.25. Comparison with WFPC2 data taken one month after the initial burst and NTT data taken on March 13 shows no evidence for fading of the extended emission. After adjusting for the probable Galactic extinction in the direction of GRB 970228 of A_v=0.7, we find that the observed nebula is consistent with the sizes of galaxies of comparable magnitude found in the Hubble Deep Field and other deep HST images, and that only 2% of the sky is covered by galaxies of similar or greater surface brightness. Therefore, the extended source observed about GRB 970228 is most likely a galaxy at moderate redshift, and is almost certainly the host of the gamma-ray burst

Rapid and highly variable warming of lake surface waters around the globe

In this first worldwide synthesis of in situ and satellite-derived lake data, we find that lake summer surface water temperatures rose rapidly (global mean = 0.34°C decade−1) between 1985 and 2009. Our analyses show that surface water warming rates are dependent on combinations of climate and local characteristics, rather than just lake location, leading to the counterintuitive result that regional consistency in lake warming is the exception, rather than the rule. The most rapidly warming lakes are widely geographically distributed, and their warming is associated with interactions among different climatic factors—from seasonally ice-covered lakes in areas where temperature and solar radiation are increasing while cloud cover is diminishing (0.72°C decade−1) to ice-free lakes experiencing increases in air temperature and solar radiation (0.53°C decade−1). The pervasive and rapid warming observed here signals the urgent need to incorporate climate impacts into vulnerability assessments and adaptation efforts for lakes.Peer reviewe

Astronomical Distance Determination in the Space Age: Secondary Distance Indicators

The formal division of the distance indicators into primary and secondary leads to difficulties in description of methods which can actually be used in two ways: with, and without the support of the other methods for scaling. Thus instead of concentrating on the scaling requirement we concentrate on all methods of distance determination to extragalactic sources which are designated, at least formally, to use for individual sources. Among those, the Supernovae Ia is clearly the leader due to its enormous success in determination of the expansion rate of the Universe. However, new methods are rapidly developing, and there is also a progress in more traditional methods. We give a general overview of the methods but we mostly concentrate on the most recent developments in each field, and future expectations. © 2018, The Author(s)

Maternal versus artificial rearing shapes the rumen microbiome having minor long-term physiological implications

Increasing productivity is a key target in ruminant science which requires better understanding of the rumen microbiota. This study investigated how maternal versus artificial rearing shapes the rumen microbiota using 24 sets of triplet lambs. Lambs within each sibling set were randomly assigned to natural rearing on the ewe (NN); ewe colostrum for 24 h followed by artificial milk feeding (NA); and colostrum alternative and artificial milk feeding (AA). Maternal colostrum feeding enhanced VFA production at weaning but not thereafter. At weaning, lambs reared on milk replacer had no rumen protozoa and lower microbial diversity, whereas natural rearing accelerated the rumen microbial development and facilitated the transition to solid diet. Differences in the rumen prokaryotic communities disappear later in life when all lambs were grouped on the same pasture up to 23 weeks of age. However, NN animals retained higher fungal diversity and abundances of Piromyces, Feramyces and Diplodiniinae protozoa as well as higher feed digestibility (+4%) and animal growth (+6.5%) during the grazing period. Nevertheless, no correlations were found between rumen microbiota and productive outcomes. These findings suggest that the early life nutritional intervention determine the initial rumen microbial community, but the persistence of these effects later in life is weak.</p

Spectroscopic observations and analysis of the peculiar SN 1999aa

We present an extensive new time series of spectroscopic data of the peculiar SN 1999aa in NGC 2595. Our data set includes 25 optical spectra between -11 and +58 days with respect to B-band maximum light, providing an unusually complete time history. The early spectra resemble those of an SN 1991T-like object but with a relatively strong Ca H and K absorption feature. The first clear sign of Si II lambda6355, characteristic of Type Ia supernovae, is found at day -7, and its velocity remains constant up to at least the first month after B-band maximum light. The transition to normal-looking spectra is found to occur earlier than in SN 1991T, suggesting SN 1999aa as a possible link between SN 1991T-like and Branch-normal supernovae. Comparing the observations with synthetic spectra, doubly ionized Fe, Si, and Ni are identified at early epochs. These are characteristic of SN 1991T-like objects. Furthermore, in the day -11 spectrum, evidence is found for an absorption feature that could be identified as high velocity C II lambda6580 or H alpha. At the same epoch C III lambda4648.8 at photospheric velocity is probably responsible for the absorption feature at 4500 8. High-velocity Ca is found around maximum light together with Si II and Fe II confined in a narrow velocity window. Implied constraints on supernovae progenitor systems and explosion hydrodynamic models are briefly discussed

A global database of lake surface temperatures collected by in situ and satellite methods from 1985–2009

Peer reviewe

Estudo da toxicidade de metais (zinco e cádmio) sobre Ceriodaphnia dubia, por multivias de exposição e recuperação biológica de descendentes

RESUMO Os metais frequentemente são avaliados em águas doces como soluções dissolvidas, assumindo que o efeito tóxico é causado unicamente por via aquática (respiração e contato). No entanto, estudos abrangendo concomitantemente a toxicidade na água e no alimento, como acontece no meio, são pouco discutidos na literatura. No presente estudo, a toxicidade de zinco e cádmio foi avaliada expondo-se Ceriodaphnia dubia simultaneamente ao alimento e ao meio aquoso. A espécie de alga verde Raphidocelis subcapitata foi exposta durante 96h a concentrações de Zn (0,18 e 0,27 mg.L-1) e Cd (0,001 e 0,0015 mg.L-1). Os resultados foram analisados estatisticamente por meio da Análise de Variância (Kruskal-Wallis). As algas foram usadas como fonte de alimento para C. dubia, durante exposição crônica (oito dias), nas mesmas concentrações. Posteriormente, os neonatos (geração F1) foram introduzidos em água e alimentação sem contaminantes, para averiguação da capacidade de recuperação biológica. Foram avaliados número de neonatos por indivíduos, morfologia dos neonatos e quantificação dos metais em tecido biológico. Os resultados demonstraram que nas concentrações testadas não houve inibição no crescimento de R. subcapitata, enquanto para C. dubia evidenciou-se toxicidade crônica pela redução na taxa reprodutiva nas duas gerações, para ambos metais. Concluiu-se que, mesmo em concentrações relativamente baixas, os metais zinco e cádmio podem alterar o padrão reprodutivo dos invertebrados de água doce, comprometendo o ecossistema aquático e sua capacidade de recuperação. Considerando os efeitos tóxicos desses metais e sua interferência no sistema biológico, novos ensaios ecotoxicológicos devem ser realizados para melhor compreensão do comportamento dessas substâncias nos organismos

EFFECTIVENESS OF DIQUAT, BOTH ISOLATED AND ASSOCIATED WITH COPPER SOURCES IN CONTROLLING THE Hydrilla verticillata SUBMERGED MACROPHYTES AND ANKISTRODESMUS Gracilis microphyte

ABSTRACT The goal of this study was to evaluate the effectiveness of diquat, both isolated and associated with copper sources (oxychloride and hydroxide) in controling the H. verticillata submerged macrophyte and the A. gracilis microalgae. For this purpose, 10.0 cm H. verticillata young branches and 300 mL of A. gracilis culture were used. The experiments were performed in laboratory and the tested diquat concentrations were: 0.1; 0.2; 0.4; 0.8; 1.2; and 1.8 mg L-1, either isolated or added with 1.0% copper oxychlorideand hydroxide, as well as a control sample. On day 3, 7, 11, 21 and 30 after application, phytotoxicity signs were evaluated and on day 60 after application, green and dry biomass production and plant length were measured. To obtain dry mass, plants remained in a greenhouse with forced air circulation at 65.0 oC, until constant weight. On day 1, 7, 15, 21, 30, 45 and 60 after application, the concentration of chlorophyll a in the water was assessed. The herbicide diquat used alone or in combination with sources copper oxychloride and hydroxide was effective in the control of H. verticillata and microalgae A. gracilis

Rapid and highly variable warming of lake surface waters around the globe

Peer reviewed. ©2015. The Authors.This is an open access article under theterms of the Creative CommonsAttribution-NonCommercial-N oDerivsLicense, which permits use and distri-bution in any medium, provided theoriginal work is properly cited, the use isnon-commerc ial and no modificationsor adaptations are made.In this first worldwide synthesis of in situ and satellite-derived lake data, we find that lake summer surface water temperatures rose rapidly (global mean = 0.34°C decade 1) between 1985 and 2009. Our analyses show that surface water warming rates are dependent on combinations of climate and local characteristics, rather than just lake location, leading to the counterintuitive result that regional consistency in lake warming is the exception, rather than the rule. The most rapidly warming lakes are widely geographically distributed, and their warming is associated with interactions among different climatic factors —from seasonally ice-covered lakes in areas where temperature and solar radiation are increasing while cloud cover is diminishing (0.72°C decade 1) to ice-free lakes experiencing increases in air temperature and solar radiation (0.53°C decade 1). The pervasive and rapid warming observed here signals the urgent need to incorporate climate impacts into vulnerability assessments and adaptation efforts for lakes