4,025 research outputs found

    Flexible arms provide constant force for pressure switch calibration

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    In-place calibration of a pressure switch is provided by a system of radially oriented flexing arms which, when rotated at a known velocity, convert the centrifugal force of the arms to a linear force along the shaft. The linear force, when applied to a pressure switch diaphragm, can then be calculated

    Costs and benefits of competitive traits in females: aggression, maternal care and reproductive success

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    Recent research has shown that female expression of competitive traits can be advantageous, providing greater access to limited reproductive resources. In males increased competitive trait expression often comes at a cost, e.g. trading off with parental effort. However, it is currently unclear whether, and to what extent, females also face such tradeoffs, whether the costs associated with that tradeoff overwhelm the potential benefits of resource acquisition, and how environmental factors might alter those relationships. To address this gap, we examine the relationships between aggression, maternal effort, offspring quality and reproductive success in a common songbird, the dark-eyed junco (Junco hyemalis), over two breeding seasons. We found that compared to less aggressive females, more aggressive females spent less time brooding nestlings, but fed nestlings more frequently. In the year with better breeding conditions, more aggressive females produced smaller eggs and lighter hatchlings, but in the year with poorer breeding conditions they produced larger eggs and achieved greater nest success. There was no relationship between aggression and nestling mass after hatch day in either year. These findings suggest that though females appear to tradeoff competitive ability with some forms of maternal care, the costs may be less than previously thought. Further, the observed year effects suggest that costs and benefits vary according to environmental variables, which may help to account for variation in the level of trait expression.Research was supported by National Science Foundation (NSF) grants to EK (BSC 05-19211 and IOS 08-20055) and an NSF Doctoral Dissertation Improvement Grant to KC (09-10036). KC was also supported by NSF Graduate Research Fellowship (www.nsfgrfp.org)

    Rewriting systems and biautomatic structures for Chinese, hypoplactic, and sylvester monoids

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    This paper studies complete rewriting systems and biautomaticity for three interesting classes of finite-rank homogeneous monoids: Chinese monoids, hypoplactic monoids, and sylvester monoids. For Chinese monoids, we first give new presentations via finite complete rewriting systems, using more lucid constructions and proofs than those given independently by Chen & Qui and GĂŒzel Karpuz; we then construct biautomatic structures. For hypoplactic monoids, we construct finite complete rewriting systems and biautomatic structures. For sylvester monoids, which are not finitely presented, we prove that the standard presentation is an infinite complete rewriting system, and construct biautomatic structures. Consequently, the monoid algebras corresponding to monoids of these classes are automaton algebras in the sense of Ufnarovskij

    The Ranger 4 Flight Path and Its Determination from Tracking Data

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    The ranger iv flight path and its determination from tracking dat

    Differential Rearing Alters Forced Swim Test Behavior, Fluoxetine Efficacy, and Post-Test Weight Gain in Male Rats

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    Citation: Arndt, D. L., Peterson, C. J., & Cain, M. E. (2015). Differential Rearing Alters Forced Swim Test Behavior, Fluoxetine Efficacy, and Post-Test Weight Gain in Male Rats. Plos One, 10(7), 21. doi:10.1371/journal.pone.0131709Environmental factors play a key role in the etiology of depression. The rodent forced swim test (FST) is commonly used as a preclinical model of depression, with increases in escape-directed behavior reflecting antidepressant effects, and increases in immobility reflecting behavioral despair. Environmental enrichment leads to serotonergic alterations in rats, but it is unknown whether these alterations may influence the efficacy of common antidepressants. Male Sprague-Dawley rats were reared in enriched (EC), standard (SC), or isolated (IC) conditions. Following the rearing period, fluoxetine (10 or 20 mg/kg, i.p.) was administered 23.5 hrs, 5 hrs, and 1 hr before locomotor and FST measures. Following locomotor testing and FST exposure, rats were weighed to assess fluoxetine-, FST-, and environmental condition-induced moderations in weight gain. Results revealed an antidepressant effect of environmental enrichment and a depressant effect of isolation. Regardless of significant fluoxetine effects on locomotor activity, fluoxetine generally decreased swimming and increased immobility in all three environmental conditions, with IC-fluoxetine (10 mg/kg) rats and EC-fluoxetine (20 mg/kg) rats swimming less than vehicle counterparts. Subchronic 20 mg/kg fluoxetine also induced significant weight loss, and differential rearing appeared to moderate weight gain following FST stress. These results suggest that differential rearing has the ability to alter FST behaviors, fluoxetine efficacy, and post-stressor well-being. Moreover, 20 mg/kg fluoxetine, administered subchronically, may lead to atypical effects of those commonly observed in the FST, highlighting the importance and impact of both environmental condition and dosing regimen in common animal models of depression

    Political Participation of Ethnic Minorities in the 1980s

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    Currently political participation, especially voter registration and turnout, varies substantially with ethnicity. Blacks and non-Hispanic whites participate at roughly equal rates, while Latinos and Asian-Americans are substantially less active, this variation may reflect cultural factors, or it may be the spurious product of differences in the distribution of non-ethnic determinants of participation, including socioeconomic and demographic characteristics, variables reflecting immigration history, including citizenship, and measures of group identification. Using data collected in 1984 on samples of California's black, Latino, Asian-American, and non-Hispanic white populations, we conclude that these other variables fully account for lower Latino participation rates. Even with such controls, however, Asian-Americans remain less likely to vote. Although non-citizens participate less than citizens, they do engage in non-electoral activities, Finally, we speculate on the future political impact of Latinos and Asian-Americans, by projecting participation rates under several scenarios

    An emerging role for microRNA in the regulation of endothelin-1

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    Endothelin-1 (ET-1) is a peptide signaling molecule serving diverse functions in many different tissues such as the vasculature and the kidney. The primary mechanism thought to control ET-1 bioavailability is the rate of transcription from the ET-1 gene (EDN1), but recent research suggests that EDN1 expression is attenuated by microRNA (miRNA)—mediated regulation. The action of specific miRNAs on EDN1 mRNA appears to vary greatly in a tissue specific manner. This review provides a summary of our current understanding of miRNA-EDN1 interaction

    In-ovulo embryo culture and seedling development of seeded and seedless grapes (Vitis vinifera L.)

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    Normal embryos and seedling plants were obtained from normally abortive ovules of seedless grapes. Ovules of seeded and seedless cultivars were excised and cultured on 10 media at 12 dates between anthesis and 101 d postanthesis. Ovules cultured from anthesis until 14 d postanthesis-grew abnormally. At 24 and 31 d after anthesis, ovules developed into normal-appearing seeds, but they contained no noticeable embryo or endosperm. Viable embryos were found in excised ovules cultured beyond 38 d after anthesis. Ovules of 1 seedless grape cultured 52 d postanthesis germinated and produced healthy seedlings. Self pollinated ovules from 7 to 13 seedless clones produced viable embryos when cultured. Open pollinated ovules and crosses between seedless clones also produced viable embryos and seedling plants. This indicates that stenospermocarpic seedless grapes can produce viable embryos. lmplications for breeding of seedless grapes are discussed.Die Kultur von Samenanlagen zur Erzeugung von Embryonen und die Entwicklung von SĂ€mlingen bei kernhaltigen und kernlosen Reben (Vitis vinifera L.)Aus normalerweise abortierenden Samenanlagen kernloser Rebsorten konnten normale Embryonen und Keimpflanzen gewonnen werden. Die Samenanlagen kernhaltiger und kernloser Sorten wurden isoliert und auf 10 verschiedenen Medien kultiviert, wobei der Entnahmezeitpunkt vom Tag der Anthese bis auf 101 d nach dem AufblĂŒhen - insgesamt 12 verschiedene Termine - ausgedehnt wurde. Samenanlagen, die bis zu 14 d nach der Anthese isoliert worden waren, zeigten ein normales Wachstum. 24 und 31 d nach der Anthese isoliert, entwickelten sich die Samenanlagen zu Ă€ußerlich normalen Samen, die aber nur degenerierte Embryonen und Endospermreste enthielten. LebensfĂ€hige Embryonen wurden gefunden, wenn die Embryonen frĂŒhestens 38 d nach der Anthese in Kultur genommen worden waren. Die Samenanlagen einer kernlosen Sorte, die 52 d nach dem AufblĂŒhen isoliert worden waren, keimten und erzeugten gesunde SĂ€mlinge. Bei SelbstbestĂ€ubung bildeten 7 von 13 kernlosen Klonen in den kultivierten Samenanlagen vitale Embryonen. Aus den kultivierten Samenanlagen frei abgeblĂŒhter oder untereinander gekreuzter kernloser Klone entstanden ebenfalls lebensfĂ€hige Embryonen und SĂ€mlinge. Die Ergebnisse weisen darauf hin, daß viele stenospermokarp kernlose Reben lebensfĂ€hige Embryonen hervorbringen können, wenn sich die Samenanlagen nur in einem angemessenen Milieu entwickeln können. Die Konsequenzen fĂŒr die ZĂŒchtung kernloser Rebsorten werden diskutiert
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