The dragonfly nearby galaxies survey. Iv. A giant stellar disk in ngc 2841

Neutral gas is commonly believed to dominate over stars in the outskirts of galaxies, and investigations of the disk-halo interface are generally considered to be in the domain of radio astronomy. This may simply be a consequence of the fact that deep HI observations typically probe to a lower mass surface density than visible wavelength data. This paper presents low surface brightness optimized visible wavelength observations of the extreme outskirts of the nearby spiral galaxy NGC 2841. We report the discovery of an enormous low-surface brightness stellar disk in this object. When azimuthally averaged, the stellar disk can be traced out to a radius of $\sim$70 kpc (5 $R_{25}$ or 23 inner disk scale lengths). The structure in the stellar disk traces the morphology of HI emission and extended UV emission. Contrary to expectations, the stellar mass surface density does not fall below that of the gas mass surface density at any radius. In fact, at all radii greater than $\sim$20 kpc, the ratio of the stellar to gas mass surface density is a constant 3:1. Beyond $\sim$30 kpc, the low surface brightness stellar disk begins to warp, which may be an indication of a physical connection between the outskirts of the galaxy and infall from the circumgalactic medium. A combination of stellar migration, accretion and in-situ star formation might be responsible for building up the outer stellar disk, but whatever mechanisms formed the outer disk must also explain the constant ratio between stellar and gas mass in the outskirts of this galaxy.Comment: 11 pages, 5 figures, accepted for publication in Ap

Robustness study of a flexible zero-energy house

The U.S. Department of Energy launched the 5th Solar-Decathlon-competition, defying student teams from all over the world to conceive a house powered exclusively by the sun. Team Belgium, of Ghent University, conceived the E-Cube, a modular and flexible house, that could be adapted depending on the inhabitants, the building site and the climate. This paper focuses on that last aspect: the robustness and flexibility of the energy concept and the design, depending on the climate it is built in. Different climates are selected for the analyses, reaching from climates with extreme winters (Canada: Saskatoon) to arid climates (US: Las Vegas), through milder climates (Belgium: Ukkel and US: Washington D.C.). To cover both locally (Belgian) and internationally used energy-assessment procedures both the Flemish EPB-software as well as the PHPP-software are used. Furthermore, dynamic simulations in Trnsys are carried out to obtain more detailed and accurate feedback on the buildings’ dynamic thermal response. Through simulations with these three calculation methods, energy robustness is tested and alternative solutions for the building envelope are proposed, adapting the building to its boundary conditions. This paper presents the results from this study, analyzing the differences due to the climate, the calculation method and the design options

Disinfection by hydrogen peroxide nebulization increases susceptibility to avian pathogenic Escherichia coli

Background: Avian pathogenic Escherichia coli (APEC) are the major cause of economic losses in the poultry industry worldwide. Traditionally, antibiotics are used to treat and prevent colibacillosis in broilers. Due to resistance development other ways of preventing/treating the disease have to be found. Therefore during this study the nebulization of low concentrations of hydrogen peroxide (H2O2) was tested in the presence of chickens to lower pathogenicity of APEC. Results: Significantly higher total lesion scores and higher E. coli concentrations were found in the spleen of chickens exposed to 2 % H2O2 compared to those exposed to 1 % H2O2 and control chickens which had been exposed to nebulization with distilled water. Higher total lesions scores and E. coli concentrations in the spleen were found in chickens exposed to 1 % H2O2 in comparison to control chickens (not significant). Conclusion: H2O2 is rendering animals more prone to APEC infection contraindicating H2O2 nebulization in the presence of chickens

Isopropyl alcohol recovery by heteroazeotropic batch distillation

Solvent recovery is becoming a major issue in the pharmaceutical and specialty chemical industries. Solvent recovery by conventional batch distillation is limited by the frequent presence of azeotropes in the used solvent mixtures. Most distillation processes for the separation of azeotropic or difficult zeotropic mixtures involve the addition of an entrainer (homogeneous and heterogeneous azeotropic distillation or extractive distillation). In this study the recovery of IPA (isopropyl alcohol) from an industrial waste stream (IPA/water mixture) was studied by conventional batch distillation and heteroazeotropic batch distillation, using cyclohexane as entrainer. First the ternary IPA/water/cyclohexane azeotrope (boiling temperature of 64.1 °C), then the binary IPA/cyclohexane azeotrope (boiling temperature of 69.3°C) and finally pure IPA was distilled. 99.96 mass% IPA could be obtained by heteroazeotropic distillation, using cyclohexane as entrainer. By using this procedure the IPA recovery is 97.6%, which is high compared to the conventional distillation techniques. The binary azeotrope could be reused in a subsequent heteroazeotropic batch distillation

Genetic parameters for litter size in sheep: natural versus hormone-induced oestrus

The litter size in Suffolk and Texel-sheep was analysed using REML and Bayesian methods. Litters born after hormonal induced oestrus and after natural oestrus were treated as different traits in order to estimate the genetic correlation between the traits. Explanatory variables were the age of the ewe at lambing, period of lambing, a year*flock-effect, a permanent environmental effect associated with the ewe, and the additive genetic effect. The heritability estimates for litter size ranged from 0.06 to 0.13 using REML in bi-variate linear models. Transformation of the estimates to the underlying scale resulted in heritability estimates from 0.12 to 0.17. Posterior means of the heritability of litter size in the Bayesian approach with bi-variate threshold models varied from 0.05 to 0.18. REML estimates of the genetic correlations between the two types of litter size ranged from 0.57 to 0.64 in the Suffolk and from 0.75 to 0.81 in the Texel. The posterior means of the genetic correlation (Bayesian analysis) were 0.40 and 0.44 for the Suffolk and 0.56 and 0.75 for the Texel in the sire and animal model respectively. A bivariate threshold model seems appropriate for the genetic evaluation of prolificacy in the breeds concerned

Full sib pens of pigs are not suitable to identify variance component of associative effect: a simulation study using Gibbs Sampling

<p>Abstract</p> <p>Background</p> <p>Accounting for and quantifying the associative effect of each animal could improve both welfare of animals and response to selection. Because of the limitation of REML, Gibbs Sampling could be an alternative technique to estimate the variance component of the associative effect. The objective of this study was to investigate the estimation accuracy of the variance component of associative effect by using simulation via Gibbs Sampling. The simulated data comprised five generations of pigs. The breeding animals of each generation were selected randomly. In the simulation, variations were introduced for the methods of assigning pens (random, mixed sib and full sib), the number of pigs per pen (5 or 10), the number of breeding animals per generation (162 or 324) and the correlation between genetic direct effect and genetic associative effect (-0.5, 0.1 or +0.5). Each set of simulation was run for 30 replications.</p> <p>Results</p> <p>Random assignment or mixed sib assignment resulted in bias of estimated variance components in only 3 of 24 combinations. Furthermore, these 3 cases occurred with 162 breeding animals. With full sib assignment, 9 out of 12 groups of estimates significantly deviated from the true parameter value. The Root Mean Square Errors obtained with the full sib assignment were higher than with the other two methods of pen assignment in most of the cases. The Root Mean Square Errors obtained with datasets with 324 breeding animals were notably smaller than the datasets from 162 breeding animals. Within each method of pen assignment, the relative bias of the associative effect was significantly smaller with group size 10 than with group size 5.</p> <p>Conclusion</p> <p>Full sib assignment caused difficulties to estimate variance components in most of the cases, due to a lack of identifiability. With random and mixed assignment, most data structures yielded unbiased results but increasing the number of breeding animals or group size improves the estimation. Thus to get identifiable and unbiased estimates of the genetic associative effect, it is recommended to avoid close genetic relationship between animals within one pen and to use sufficient numbers of breeding animals and sufficient group sizes.</p

An integration of external information for foreign stallions into the Belgian genetic evaluation for jumping horses

The aim of this study was to test the integration of external information, i.e. foreign estimated breeding values (EBV) and the associated reliabilities (REL), for stallions into the Belgian genetic evaluation for jumping horses. The Belgian model is a bivariate repeatability Best Linear Unbiased Prediction animal model only based on Belgian performances while Belgian breeders import horses from neighbouring countries. Thereby, use of external information is needed as prior to achieve more accurate EBV. Pedigree and performance data contained 101,382 horses and 712,212 performances, respectively. After conversion to the Belgian trait, external information of 98 French and 67 Dutch stallions were integrated into the Belgian evaluation. Resulting Belgian rankings of the foreign stallions were more similar to foreign rankings according to the increase of the rank correlations of at least 12%. REL of their EBV were improved of at least 2% on average. External information was partially to totally equivalent to 4 years of contemporary horses’ performances or to all the stallions’ own performances. All these results showed the interest to integrate external information into the Belgian evaluation

The monotypic Brazilian genus Diacrodon is a synonym of Borreria (Spermacoceae, Rubiaceae): Morphological and molecular evidences

Diacrodon is a monotypic genus of the tribe Spermacoceae (Rubiaceae), endemic to northeastern Brazil. Diacrodon compressus is frequently misidentified with a two lobed calyx species of Borreria, B. verticillata. Traditionally, in Spermacoceae the fruit type was considered a diagnostic character among the genera. In this sense, D. compressus presents a strongly compressed, one seeded and indehiscent fruit (vs. globose, two seeded and dehiscent fruit in B. verticillata). In this work, we address two objectives: evaluate the systematic position and determine the identity of Diacrodon in respect to other taxa. Molecular analyses using ITS and ETS indicate that D. compressus is strongly related to other species of Borreria. The morphological results revealed that D. compressus, despite of its type of fruit, is identical to Borreria in floral and palynological features. As conclusion, the new combination Borreria diacrodonta is made and a lectotype is designated. An updated description of the species and a key to the Borreria species with a two lobed calyx are provided. The distribution of B. diacrodonta is extended to Brazilian states Goiás and Minas Gerais, and Paraguay. By this taxonomical change it has become clear that the dehiscence of the fruits lack taxonomic value in the delimitation of Borreria.Fil: Miguel, Laila Mabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; ArgentinaFil: Sobrado, Sandra Virginia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; ArgentinaFil: Janssens, Steven. Botanic Garden Meise; BélgicaFil: Dessein, Steven. Botanic Garden Meise; BélgicaFil: Cabral, Elsa Leonor. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; Argentina. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas y Naturales y Agrimensura; Argentin

Habitat fragmentation affects climate adaptation in a forest herb

Climate change and increased drought frequencies are expected to have a major impact on forest herb persistence. The adaptive capacity of forest herbs will depend on their long standing imprints of local adaptation and phenotypic plasticity. To evaluate how local adaptation to habitat fragmentation affects climate adaptation we quantified a wide range of traits in a common garden experiment of Primula elatior. Specifically, we disentangled the relative contribution of climate, habitat fragmentation, and drought stress on trait variation of the germination lag time, germination rate, growth rate, root:shoot ratio, specific leaf area, stomatal density, glandular trichome density, flower phenology and flower investment. To further evaluate mating shifts we quantified flower colour adaptations, herkogamy, and self-incompatibility. Local adaptations in P. elatior displayed strong alignment with climate along its range. Northern populations displayed a reduced establishment and competitive potential, while southern populations displayed a high sensitivity to increased drought stress under climate change. Habitat fragmentation resulted in the evolutionary breakdown of reciprocal herkogamy, and a biochemical self-compatibility in S morphs. Furthermore, a significant differentiation of the flower colour attraction patterns and a strongly reduced flowering investment was observed in the south of the range. Fragmented populations also displayed a strategic developmental focus on survival and stress resistance. The interaction between local adaptation to climate and habitat fragmentation could have far reaching effects on (meta-)population dynamics under climate change and could limit the successful application of assisted migration strategies