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  • 1
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    Readdressing working fluid selection with a view to designing a variable geometry ejector (2015)
    Oxford University Press
    Details
    Publication Date: 2015-08-16
    Description: A number of factors influence the performance of an ejector, e.g. working fluid, geometry and operating conditions. In the present work, six low-environmental-impact working fluids were evaluated for their use in an ejector cooling system running on low-temperature thermal energy. The numerical analysis was based on a model applying the 1D constant-pressure mixing theory. Ejector performance was assessed for the temperatures of the generator, evaporator and condenser in the range of 80–120°C, 5–15°C and 25–40°C, respectively. The results indicated that owing to its high coefficient of performance and moderate operating pressures throughout the entire ejector cycle, isobutane is a good choice for a refrigerant. The area ratio required for running the ejector in critical mode, under changing operating conditions, varied in a significant range regardless of the selected refrigerant. This clearly indicates the importance of a variable geometry ejector design to strengthen the position of ejector cooling systems among other refrigeration technologies.
    Keywords: Other low-carbon energy technologies
    Print ISSN: 1748-1317
    Electronic ISSN: 1748-1325
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Oxford University Press
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  • 2
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    Fauna in decline: meek shall inherit (2014)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2014-09-06
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Christianini, Alexander V -- Oliveira, Paulo S -- Bruna, Emilio M -- Vasconcelos, Heraldo L -- New York, N.Y. -- Science. 2014 Sep 5;345(6201):1129. doi: 10.1126/science.345.6201.1129-a.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Departamento de Ciencias Ambientais, Universidade Federal de Sao Carlos, Sorocaba SP, 18052-780, Brazil. avchrist@ufscar.br. ; Departmento de Biologia Animal, Universidade Estadual de Campinas, CP 6109, Campinas SP, 13083-970, Brazil. ; Department of Wildlife Ecology and Conservation, University of Florida, Gainesville, FL 32611-0430, USA. Center for Latin American Studies, University of Florida, Gainesville, FL 32611-5530, USA. ; Instituto de Biologia, Universidade Federal de Uberlandia, Uberlandia MG, 38400-902, Brazil.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25190784" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Biodiversity ; *Endangered Species ; *Extinction, Biological ; *Human Activities ; Humans
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 3
    Electronic Resource
    Electronic Resource
    Regulation of reproduction in the neotropical ponerine ant,Pachycondyla villosa (1996)
    Springer
    Journal of insect behavior 9 (1996), S. 441-450 
    Details
    ISSN: 1572-8889
    Keywords: dominance ; reproduction ; queen inhibition ; Ponerinae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Workers in queenless groups of the antPachycondyla villosa engage in antennal boxing and biting and by these interactions establish social dominance hierarchies, in which several high-ranking individuals may lay eggs. We observed egg cannibalism by dominant workers. The presence of larvae negatively effects the number of worker-produced eggs in queenless colony fragments in two ways. First, larvae feed on the eggs, and second, workers lay fewer eggs when larvae are present. In queenright colonies, workers lay eggs at a low rate, which are eaten by the queen or fed to the brood, but apparently they do not compete aggressively for egg-laying.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02214021
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  • 4
    Electronic Resource
    Electronic Resource
    Communication in the migratory termite-hunting ant Pachycondyla (= Termitopone) marginata (Formicidae, Ponerinae) (1996)
    Springer
    Journal of comparative physiology 178 (1996), S. 47-53 
    Details
    ISSN: 1432-1351
    Keywords: Recruitment trails ; Pheromones ; Pygidial gland ; Citronellal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The Neotropical species Pachycondyla marginata conducts well-organized predatory raids on the termite species Neocapritermes opacus and frequently emigrates to new nest sites. During both activities the ants employ chemical trail communication. The trail pheromone orginates from the pygidial gland. Among the substances identified in the pygidial gland secretions, only citronellal was effective as a trail pheromone. Isopulegol elicited an increase in locomotory activity in the ants and may function as a synergist recruitment signal. The chemical signal is enhanced by a shaking display performed by the recruiting ant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00189589
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  • 5
    Electronic Resource
    Electronic Resource
    Conditional outcomes in a neotropical treehopper-ant association: temporal and species-specific variation in ant protection and homopteran fecundity (2000)
    Springer
    Oecologia 124 (2000), S. 156-165 
    Details
    ISSN: 1432-1939
    Keywords: Key words Ants ; Conditional mutualism ; Guayaquila xiphias ; Species-specific effects ; Treehopper-ant association
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  We studied the association between the honeydew-producing membracid Guayaquila xiphias and its tending ants in the cerrado savanna of Brazil, during 1992 and 1993. Results showed that ants attack potential enemies of G. xiphias, and that increased ant density near the treehoppers affects the spatial distribution of parasitoid wasps on the host plant, keeping them away from brood-guarding G. xiphias females. Controlled ant-exclusion experiments revealed that ant presence (seven species) reduces the abundance of G. xiphias’ natural enemies (salticid spiders, syrphid flies, and parasitoid wasps) on the host plant. The data further showed that ant-tending not only increased homopteran survival, but also conferred a direct reproductive benefit to G. xiphias females, which may abandon the first brood to ants and lay an additional clutch next to the original brood. Two years of experimental manipulations, however, showed that the degree of protection conferred by tending ants varies yearly, and that at initially high abundance of natural enemies the ant species differ in their effects on treehopper survival. Ant effects on treehopper fecundity also varied with time, and with shifts in the abundance of natural enemies. This is the first study to simultaneously demonstrate conditionality in ant-derived benefits related to both protection and fecundity in an ant-tended Membracidae, and the first to show the combined action of these effects in the same system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004420050002
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  • 6
    Electronic Resource
    Electronic Resource
    Ant foraging on extrafloral nectaries of Qualea grandiflora (Vochysiaceae) in cerrado vegetation: ants as potential antiherbivore agents (1987)
    Springer
    Oecologia 74 (1987), S. 228-230 
    Details
    ISSN: 1432-1939
    Keywords: Ant foraging ; Extrafloral nectaries ; Qualea ; Cerrado vegetation ; Ant-plant mutualism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Qualea grandiflora is a typical tree of Brazilian cerrados (savanna-like vegetation) that bears paired extrafloral nectaries (EFNs) along its stems. Results show that possession of EFNs increases ant density on Q. grandiflora shrubs over that of neighbouring non-nectariferous plants. Frequency of ant occupancy and mean number of ants per plant were much higher on Qualea than on plants lacking EFNs. These differences resulted in many more live termitebaits being attacked by foraging ants on Qualea than on neighbours without EFNs. Termites were attacked in equal numbers and with equal speeds on different-aged leaves of Qualea. The greatest potential for herbivore deterrence was presented by Camponotus ants (C. crassus, C. rufipes and C. aff. blandus), which together attacked significantly more termites than nine other ant species grouped. EFNs are regarded as important promoters of ant activity on cerado plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00379363
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  • 7
    Electronic Resource
    Electronic Resource
    Behavioral ecology of the neotropical termite-hunting ant Pachycondyla (= Termitopone) marginata: colony founding, group-raiding and migratory patterns (1995)
    Springer
    Behavioral ecology and sociobiology 37 (1995), S. 373-383 
    Details
    ISSN: 1432-0762
    Keywords: Key words Colony founding ; Termite-hunting ; Group raiding ; Migration ; Ponerine ants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This study provides the first detailed field account of colony founding, group-raiding and migratory habits in the neotropical termite-hunting ant Pachycondyla marginata, in a semi-deciduous forest in south-east Brazil. New colonies can originate by haplometrosis, pleometrosis, or colony fission. Incipient colonies with multiple foundresses persisted longer in the field, and most excavated nests contained more than one dealated female. A total of 202 group raids by P. marginata were registered, and in all cases the raided termite species was Neocapritermes opacus. Nearly 20% of the workers within a colony engage with raiding activity. Colonies of P. marginata hunt for termites approximately every 2–3 weeks, and group-raids may last for more than 24 h. Target termite nests are up to 38 m from the ant colony, and occasionally two nests are simultaneously raided by one ant colony. Raiding ants carry 1 or 2 paralysed prey, and nearly 1600 termites can be captured during a 9-h raid. Migration by P. marginata colonies lasted over 2 days and covered distances of 2–97 m (n = 48). Average residence time at a given location was 150 days. Three basic migratory patterns were noted: colony fission (only part of the colony moves), long-distance migrations, and short-distance migrations. Both raiding and migratory activities appeared to be strongly affected by seasonal factors. The group raiding and migratory patterns of P. marginata are compared with other ant taxa with similar habits. It is concluded that P. marginata presents a rudimentary form of the so-called “army ant behavior”, which is highly developed in the subfamilies Dorylinae and Ecitoninae. The extremely specialized diet of P. marginata and the associated high costs of migration are features likely to prevent it from evolving a full army ant life pattern.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002650050204
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  • 8
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    Shotgun sequencing of the human transcriptome with ORF expressed sequence tags (2000)
    National Academy of Sciences
    Details
    Publication Date: 2000-03-28
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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  • 9
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    Structural shifts of aldehyde dehydrogenase enzymes were instrumental for the early evolution of retinoid-dependent axial patterning in metazoans [Evolution] (2011)
    National Academy of Sciences
    Details
    Publication Date: 2011-01-05
    Description: Aldehyde dehydrogenases (ALDHs) catabolize toxic aldehydes and process the vitamin A-derived retinaldehyde into retinoic acid (RA), a small diffusible molecule and a pivotal chordate morphogen. In this study, we combine phylogenetic, structural, genomic, and developmental gene expression analyses to examine the evolutionary origins of ALDH substrate preference. Structural modeling reveals that processing of small aldehydes, such as acetaldehyde, by ALDH2, versus large aldehydes, including retinaldehyde, by ALDH1A is associated with small versus large substrate entry channels (SECs), respectively. Moreover, we show that metazoan ALDH1s and ALDH2s are members of a single ALDH1/2 clade and that during evolution, eukaryote ALDH1/2s often switched between large and small SECs after gene duplication, transforming constricted channels into wide opened ones and vice versa. Ancestral sequence reconstructions suggest that during the evolutionary emergence of RA signaling, the ancestral, narrow-channeled metazoan ALDH1/2 gave rise to large ALDH1 channels capable of accommodating bulky aldehydes, such as retinaldehyde, supporting the view that retinoid-dependent signaling arose from ancestral cellular detoxification mechanisms. Our analyses also indicate that, on a more restricted evolutionary scale, ALDH1 duplicates from invertebrate chordates (amphioxus and ascidian tunicates) underwent switches to smaller and narrower SECs. When combined with alterations in gene expression, these switches led to neofunctionalization from ALDH1-like roles in embryonic patterning to systemic, ALDH2-like roles, suggesting functional shifts from signaling to detoxification.
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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  • 10
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    Genome-Enabled Prediction of Breeding Values for Feedlot Average Daily Weight Gain in Nelore Cattle (2017)
    Genetics Society of America (GSA)
    Details
    Publication Date: 2017-06-08
    Description: Nelore is the most economically important cattle breed in Brazil, and the use of genetically improved animals has contributed to increased beef production efficiency. The Brazilian beef feedlot industry has grown considerably in the last decade, so the selection of animals with higher growth rates on feedlot has become quite important. Genomic selection (GS) could be used to reduce generation intervals and improve the rate of genetic gains. The aim of this study was to evaluate the prediction of genomic-estimated breeding values (GEBV) for average daily weight gain (ADG) in 718 feedlot-finished Nelore steers. Analyses of three Bayesian model specifications [Bayesian GBLUP (BGBLUP), BayesA, and BayesC] were performed with four genotype panels [Illumina BovineHD BeadChip, TagSNPs, and GeneSeek High- and Low-density indicus (HDi and LDi, respectively)]. Estimates of Pearson correlations, regression coefficients, and mean squared errors were used to assess accuracy and bias of predictions. Overall, the BayesC model resulted in less biased predictions. Accuracies ranged from 0.18 to 0.27, which are reasonable values given the heritability estimates (from 0.40 to 0.44) and sample size (568 animals in the training population). Furthermore, results from Bos taurus indicus panels were as informative as those from Illumina BovineHD, indicating that they could be used to implement GS at lower costs.
    Electronic ISSN: 2160-1836
    Topics: Biology
    Published by Genetics Society of America (GSA)
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