The Need for Laboratory Measurements and Ab Initio Studies to Aid Understanding of Exoplanetary Atmospheres

Laboratory astrophysics and astrochemistr

A comprehensive reanalysis of Spitzer's 4.5 μm phase curves, and the phase variations of the ultra-hot Jupiters MASCARA-1b and KELT-16b

We have developed an open-source pipeline for the analysis of Spitzer/IRAC channel 1 and 2 time-series photometry, incorporating some of the most popular decorrelation methods. We applied this pipeline to new phase curve observations of ultra-hot Jupiters MASCARA-1b and KELT-16b, and we performed the first comprehensive reanalysis of 15 phase curves. We find that MASCARA-1b and KELT-16b have phase offsets of 6+11−11 ∘W and 38+16−15 ∘W, dayside temperatures of 2952+100−97 and 3070+160−150 K, and nightside temperatures of 1300+340−340 and 1900+430−440 K, respectively. We confirm a strong correlation between dayside and irradiation temperatures with a shallower dependence for nightside temperature. We also find evidence that the normalized phase curve amplitude (peak-to-trough divided by eclipse depth) is correlated with stellar effective temperature. In addition, while our different models often retrieve similar parameters, significant differences occasionally arise between them, as well as between our preferred model and the literature values. Nevertheless, our preferred models are consistent with published phase offsets to within −8 ± 21 degrees (−1.6 ± 3.2 sigma), and normalized phase curve amplitudes are on average reproduced to within −0.01 ± 0.24 (−0.1 ± 1.6 sigma). Finally, we find that BLISS performs best in most cases, but not all; we therefore recommend future analyses consider numerous detector models to ensure an optimal fit and to assess model dependencies

Desempenho de animais alimentados com lâminas foliares, em pastagem de capim-marandu Performance of animals fed with green leaf in marandu grass pasture

O objetivo deste trabalho foi avaliar o desempenho de animais, alimentados com lâminas de folhas verdes (LFV) a 4, 8, 12 e 16% do peso vivo por dia, em pastagens de capim-marandu. O experimento foi conduzido em delineamento de blocos ao acaso, com duas repetições. A avaliação do desempenho dos novilhos F1 Nelore e Charolês foi realizada de outubro de 2002 a junho de 2005, nas estações das águas, em Dourados, MS. Cada unidade experimental foi pastejada em regime de pastejo contínuo e carga animal variável, com quatro animais traçadores que permaneceram no experimento dos 15 aos 23 meses de idade, quando foram abatidos. Foi obtido efeito linear entre as ofertas pretendidas e as observadas. A consistência da ingestão de folhas verdes, independentemente das ofertas, foi evidenciada em novilhos fistulados no esôfago. O ganho médio diário apresentou resposta quadrática às ofertas de LFV, com máximo resultado com a oferta de 11,7% do peso vivo. A carga animal e o ganho por hectare apresentaram resposta quadrática negativa ao aumento das ofertas. As ofertas de 8 a 12% do peso vivo permitem que os animais consumam as folhas verdes, com boa qualidade da dieta.<br>The objective of this work was to evaluate the performance of animals, fed with green leaves at 4, 8, 12 and 16% of live weight per day, in marandu grass pastures. The experimental design was in complete randomized blocks, with two replications. Animal performance evaluations were made from October 2002 to June 2005, with steers F1 Nelore and Charolais, along the rainy seasons, in Dourados County, Mato Grosso do Sul, Brazil. Four tester animals - 15 to 23 months old - grazed each experimental unit, under continuous grazing and put-and-take technique; the animals were, afterwards, slaughtered. Linear effect was obtained for the intended and observed forage allowances. The consistency of green leaf ingestions by the animals (independently of the offers) was evidenced in esophagus-fistulated steers. The average daily gain showed quadratic response in relation to the green leaf offers, with its optimum level at 11.7% live weight. Stoking rate and live weight gain per hectare presented a negative quadratic effect to the increase of blade dry matter offers. The offers of 8 to 12% live weight allow animals to feed on green leaf blades and to have a good quality diet

The digestive performance of mammalian herbivores: why big may not be that much better

1. A traditional approach to the nutritional ecology of herbivores is that larger animals can tolerate a diet of lesser quality due to a higher digestive efficiency bestowed on them by comparatively long ingesta retention times and lower relative energy requirements. 2. There are important physiological disadvantages that larger animals must compensate for, namely a lower gut surface : gut volume ratio, larger ingesta particle size and greater losses of faecal bacterial material due to more fermentation. Compensating adaptations could include an increased surface enlargement in larger animals, increased absorption rates per unit of gut surface, and increased gut motility to enhance mixing of ingesta. 3. A lower surface : volume ratio, particularly in sacciform forestomach structures, could be a reason for the fact that methane production is of significant scope mainly in large herbivores and not in small herbivores with comparably long retention times; in the latter, the substrate for methanogenesis – the volatile fatty acids – could be absorbed faster due to a more favourable gut surface : volume ratio. 4. Existing data suggest that in herbivores, an increase in fibre digestibility is not necessarily accompanied by an increase in overall apparent dry matter digestibility. This indicates a comparative decrease of the apparent digestibility of non-fibre material, either due to a lesser utilization of non-fibre substrate or an increased loss of endogenous/bacterial substance. Quantitative research on these mechanisms is warranted in order to evaluate whether an increase in body size represents a net increase of digestive efficiency or just a shift of digestive focus