241 research outputs found

    Measured and predicted noise of the Avco-Lycoming YF-102 turbofan noise

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    Acoustic testing of the AVCO-Lycoming YF-102 turbofan engine was done on a static test stand in support of the quiet short-haul research aircraft acoustic design. Overall noise levels were dominated by the fan noise emanating from the exhaust duct, except at high power settings when combination tones were generated in the fan inlet. Component noise levels, calculated by noise prediction methods were in reasonable agreement with the measured results. Far-field microphones placed at ground level were found superior to those at engine centerline height, even at high frequencies

    NEOWISE Reactivation Mission Year One: Preliminary Asteroid Diameters and Albedos

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    We present preliminary diameters and albedos for 7,959 asteroids detected in the first year of the NEOWISE Reactivation mission. 201 are near-Earth asteroids (NEAs). 7,758 are Main Belt or Mars-crossing asteroids. 17% of these objects have not been previously characterized using WISE or NEOWISE thermal measurements. Diameters are determined to an accuracy of ~20% or better. If good-quality H magnitudes are available, albedos can be determined to within ~40% or better.Comment: 42 pages, 5 figure

    Paternal effects correlate with female reproductive stimulation in the polyandrous ladybird Cheilomenes sexmaculata

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    Citation: Mirhosseini, M., Michaud, J., Jalali, M., & Ziaaddini, M. (2014). Paternal effects correlate with female reproductive stimulation in the polyandrous ladybird Cheilomenes sexmaculata. Bulletin of Entomological Research, 104(4), 480-485. https://doi.org/10.1017/S0007485314000194Components of male seminal fluids are known to stimulate fecundity and fertility in females of numerous insect species and paternal effects on offspring phenotype are also known, but no studies have yet demonstrated links between male effects on female reproduction and those on progeny phenotype. In separate laboratory experiments employing 10-day-old virgin females of Cheilomenes sexmaculata (F.), we varied male age and mating history to manipulate levels of male allomones and found that the magnitude of paternal effects on progeny phenotype was correlated with stimulation of female reproduction. Older virgin males remained in copula longer than younger ones, induced higher levels of female fecundity, and sired progeny that developed faster to yield heavier adults. When male age was held constant (13 days), egg fertility declined as a function of previous male copulations, progeny developmental times increased, and the adult weight of daughters declined. These results suggest that male epigenetic effects on progeny phenotype act in concert with female reproductive stimulation; both categories of effects increased as a consequence of male celibacy (factor accumulation), and diminished as a function of previous matings (factor depletion). Male factors that influence female reproduction are implicated in sexual conflict and parental effects may extend this conflict to offspring phenotype. Whereas mothers control the timing of oviposition events and can use maternal effects to tailor progeny phenotypes to prevailing or anticipated conditions, fathers cannot. Since females remate and dilute paternity in polyandrous systems, paternal fitness will be increased by linking paternal effects to female fecundity stimulation, so that more benefits accrue to the male's own progeny

    Dependence of DNA persistence length on ionic strength and ion type

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    Even though the persistence length LPL_P of double-stranded DNA plays a pivotal role in cell biology and nanotechnologies, its dependence on ionic strength II lacks a consensual description. Using a high-throughput single-molecule technique and statistical physics modeling, we measure LPL_P in presence of monovalent (Li+^+, Na+^+, K+^+) and divalent (Mg2+^{2+}, Ca2+^{2+}) metallic and alkyl ammonium ions, over a large range 0.5 mM I5\leq I\leq 5 M. We show that linear Debye-H\"uckel-type theories do not describe even part of these data. By contrast, the Netz-Orland and Trizac-Shen formulas, two approximate theories including non-linear electrostatic effects and the finite DNA radius, fit our data with divalent and monovalent ions, respectively, over the whole II range. Furthermore the metallic ion type does not influence LP(I)L_P(I), in contrast to alkyl ammonium monovalent ions at high II.Comment: 5 pages, 3 figures + 7 pages of supplemental informatio

    A gyűjtőcsatorna meghatározó szerepe a vese lokális renin-angiotenzin rendszerében

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    A renin-angiotenzin rendszer szervezetünk egyik legjelentősebb hormonális rendszere, amelynek juxtaglomerularis apparátusban történő szabályozása és szerepe jól ismert. Jelen összefoglaló a vese embrionális fejlődésével párhuzamot állítva a gyűjtőcsatorna renintermelését írja le, valamint ennek lokális szerepét és terápiás célpontként szolgáló lehetőségeit igyekszik feltárni. Nemrégiben került leírásra, hogy krónikus angiotenzin- II-kezelés során, két vese-, egy klip modellben, illetve diabetes mellitusban a gyűjtőcsatorna jelenti az intrarenalis (pro)renintermelés legfőbb helyét. Ebben a lokalizációban a (pro)renin előtt út nyílhat az interstitialis renin-angoitenzin rendszer komponensek, a szisztémás keringés és a nemrégiben leírásra került (pro)reninreceptor felé. A (pro)renin saját receptorán keresztül intracelluláris profibroticus utakat képes aktiválni, így egyúttal potenciálisan új célpontja lehet a hypertoniához kapcsolódó vagy diabeteses nephropathia kezelésének, illetve eszköze a krónikus vesekárosodást előidéző folyamatok korai diagnosztizálásának. Orv. Hetil., 2013, 154, 643–649

    Dependence of DNA persistence length on ionic strength of solutions with monovalent and divalent salts: a joint theory-experiment study

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    Using high-throughput Tethered Particle Motion single molecule experiments, the double-stranded DNA persistence length, LpL_p, is measured in solutions with Na+^+ and Mg2+^{2+} ions of various ionic strengths, II. Several theoretical equations for Lp(I)L_p(I) are fitted to the experimental data, but no decisive theory is found which fits all the LpL_p values for the two ion valencies. Properly extracted from the particle trajectory using simulations, LpL_p varies from 30~nm to 55~nm, and is compared to previous experimental results. For the Na+^+ only case, LpL_p is an increasing concave function of I1I^{-1}, well fitted by Manning's electrostatic stretching approach, but not by classical Odjik-Skolnick-Fixman theories with or without counter-ion condensation. With added Mg2+^{2+} ions, LpL_p shows a marked decrease at low II, interpreted as an ion-ion correlation effect, with an almost linear law in I1I^{-1}, fitted by a proposed variational approach

    L'arxiu patrimonial Fontcuberta (segles X-XXI)

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    Aquest article analitza la importància dels arxius patrimonials catalans, fixant l'atenció en un d'ells: l'arxiu Fontcuberta. Se n'estudien les característiques principals, la seva organització i la seva utilitat per a la recerca històrica. La documentació del mateix arxiu és la que proporciona informació per a conèixer-lo amb profunditat. Aquest arxiu, a més, és un complement per a altres arxius patrimonials, en posar de manifest la importància que té l'estudi exhaustiu de la documentació conservada en aquests arxius.This article analyses the importance of Catalan heritage archives, looking in more detail at one of them: the Fontcuberta Archive. We study its main characteristics, how it's organised and its relevance for historical research. The documents contained within this collection offer information that reveals more details about the archive itself. This archive also complements other heritagearchives, highlighting the importance of an exhaustive study of the documents kept in such archives
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