538 research outputs found
Equilibrium transition study for a hybrid MAV
No full textWind tunnel testing was performed on a VTOL aircraft in order to characterize longitudinal flight behavior during an equilibrium transition between vertical and horizontal flight modes. Trim values for airspeed, pitch, motor speed and elevator position were determined. Data was collected by independently varying the trim parameters, and stability and control derivatives were identified as functions of the trim pitch angle. A linear fractional representation model was then proposed, along with several methods to improve longitudinal control of the aircraft
The cecal appendix is correlated with greater maximal longevity in mammals
No full textInternational audienceThe cecal appendix had been considered as a useless vestige since Darwin's work, but recent research questioned this idea demonstrating that the cecal appendix appeared among the mammals at least 80 million years ago and has made multiple and independent appearances without any obvious correlation with diet, social life, ecology, or size of the cecum. However, functions and probable selective advantage conferred by this anatomical structure still remain enigmatic. We found, through analyses of data on 258 mammalian species, that cecal appendix presence is correlated with increased maximal observed longevity. This is the first demonstration of a correlation between cecal appendix presence and life history. Interestingly, the classical evolutionary theory of aging that predicts an increased longevity when the extrinsic mortality is reduced has been questioned several times, but recent comparative studies asserted its validity in the taxa, which experience age-dependent and density-dependent mortality, as in mammals. Thus, the cecal appendix may contribute to the increase in longevity through a reduction of extrinsic mortality. A lower risk of fatal infectious diarrhea is one of the most plausible hypotheses that could explain it. However, several hypotheses coexist about the possible functions of the cecal appendix, and our results provide new insights about this much-disputed question. In addition, we show that the cecal appendix arose at least 16 times and was lost only once during the evolutionary history of the considered mammals, an asymmetry that supports the existence of a positive selective of this structure
L’appendice iléo-cæcal intègre la mystérieuse équation des déterminants de la longévité chez les mammifères
No full textInternational audienc
Critical Evaluation and Calorimetric Study of the Thermodynamic Properties of Na2CrO4, K2CrO4, Na2MoO4, K2MoO4, Na2WO4, and K2WO4
No full textFunding Information: Ms. Sara Benalia would like to thank the Canada Research Chair in Computational Thermodynamics for High Temperature Sustainable Processes held by Professor Patrice Chartrand and the Johan Gadolin Process Chemistry Centre for the 5 month-mobility grant awarded for her stay at Åbo Akademi University (Turku, Finland). The authors would like to thank Mr. Peter Backman and Ms. Jaana Paananen for operating the DSC apparatus, Ms. Evguenia Sokolenko for helping locate old articles and for translating them into English, Dr. Paul Lafaye for fruitful discussions, and Mr. Maxime Aubé for his helpful comments on the manuscript. Publisher Copyright: © 2023 Author(s).This paper evaluates crystallographic data and thermodynamic properties for sodium chromate, potassium chromate, sodium molybdate, potassium molybdate (K2MoO4), sodium tungstate, and potassium tungstate collected from the literature. A thorough literature review was carried out to obtain a good understanding of the available data, and a critical evaluation has been performed from room temperature to above the melting temperatures. Also, the solid-solid transition and melting properties of the six pure salts were measured by differential scanning calorimetry, and high-temperature x-ray powder diffraction measurements were performed to determine the crystal structures and space groups associated with the phases of K2MoO4. This work is the first step towards the development of a thermodynamic model for the Na+, K+//Cl−, SO42−, CO32−, CrO42−, Cr2O72−, MoO42−, Mo2O72−, WO42−, W2O72−, O2− system that is relevant for high temperature corrosion in atmospheres containing O-H-S-C-Cl and alkali salts.Peer reviewe
Correlation between the presence of a cecal appendix and reduced diarrhea severity in primates: new insights into the presumed function of the appendix
No full textAbstract Increased severity or recurrence risk of some specific infectious diarrhea, such a salmonellosis or Clostridium difficile colitis, have been reported after an appendectomy in human patients. While several other mammals also possess an appendix, the suspected protective function against diarrhea conferred by this structure is known only in humans. From a retrospective collection of veterinary records of 1251 primates attributed to 45 species, including 13 species with an appendix and 32 without, we identified 2855 episodes of diarrhea, 13% of which were classified as severe diarrhea requiring a therapeutic medication or associated with a fatal issue. We identified a lower risk of severe diarrhea among primate species with an appendix, especially in the early part of life when the risk of diarrhea is maximal. Moreover, we observed a delayed onset of diarrhea and of severe diarrhea in species possessing an appendix. Interestingly, none of the primates with an appendix were diagnosed, treated or died of an acute appendicitis during the 20 years of veterinarian follow-up. These results clarify the function of the appendix among primates, as protection against diarrhea. This supports its presumed function in humans and is congruent with the existence of a selective advantage conferred by this structure
Author Correction: Vertically oriented low-dimensional perovskites for high-efficiency wide band gap perovskite solar cells
No full textCorrection to: Nature Communicationshttps://doi.org/10.1038/s41467-024-53339-6, published online 21 October 2024 In this article the sentence ‘A plane wave energy cut-off of 500 eV and a Brillouin zone sampling using Γ-centred k-mesh are employed done REMOVE DONE for all the calculations’ should have read ‘A plane wave energy cut-off of 500 eV and a Brillouin zone sampling using Γ-centred k-mesh are employed for all the calculations.’ The original article has been corrected.</p
Author Correction: Comprehensive analysis of chromothripsis in 2,658 human cancers using whole-genome sequencing
No full textauthor correctio
Dust Successive Generations in Ar/SiH4: Dust Cloud Dynamics
No full textCopyright 2008 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in AIP Conference Proceedings and may be found at http://link.aip.org/link/?APCPCS/1041/285/1International audienceSuccessive generations of dust particles in an Ar/SiH4 plasma, are shown to take place in the void region. We evidence that this cyclic phenomenon is also related to self-excited low frequency oscillations. These different results are obtained by correlating several diagnostics. We studied dust particle successive generations and the related dust cloud dynamics in silane based plasmas. Indeed, the growth of silicon nanoparticles is known to follow a well-defined cycle. Thanks to the correlation of various diagnostics (electrical, optical, ex-situ SEM), we evidenced a void region in the plasma and its specific structure. We especially showed that dust new generations grow inside this void region close to the plasma center. Moreover, an instability phenomenon linked to this cyclic growth in the void has been brought to the fore
Particular Threshold Behavior of Dusty Plasma Instabilities
No full textCopyright 2008 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in AIP Conference Proceedings and may be found at http://link.aip.org/link/?APCPCS/1041/5/1.International audienceWe show that some experimentally observed instabilities, concerning the void region of a dust cloud, are similar to oscillations obtained in chemical systems or neuronal dynamics. The time evolution of these instabilities follows a well-defined process particularly visible in the instability shape and frequency. Dust voids are often encountered in dusty plasma experiments. These dust-free regions are considered to be maintained by an equilibrium between inward electrostatic and outward ion drag forces. This equilibrium can be disturbed, leading to void size oscillations (heartbeat instability). When the instability is about to end, failed void contractions are observed. We analyzed this ending phase by using electrical and optical diagnostics. High speed video imaging is also used to record dust cloud and plasma emission behavior. Comparisons with oscillations observed in neuronal activity and chemistry are performed and close similarities are underlined
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