Notre étude porte sur la caractérisation expérimentale et numérique de la dynamique des ondes de détonation dans des prémélanges gazeux non-uniformément distribués dont les gradients de composition sont orientés selon la direction de propagation de la détonation. Elle vise à améliorer la compréhension des phénomènes complexes présents dans une chambre de combustion de moteur à détonations pulsées (PDE) ou rotatives (RDE) et dans des situations de fuites accidentelles de combustibles. Nous rappelons d’abord le contexte de notre étude, la phénoménologie de la détonation dans les gaz et les travaux antérieurs sur la propagation de la détonation dans des compositions non-uniformes. Nous décrivons ensuite le banc expérimental que nous avons conçu pour satisfaire à la contrainte de génération contrôlée de gradients de composition dans une chambre d’étude de section carrée 50⇥50 mm2 et de longueur 665 mm, et les diagnostics que nous avons mis en œuvre : sondes à oxygène, capteurs de pression dynamique, enregistrements sur plaques recouvertes d’un dépôt de carbone, strioscopie et spectroscopie par chimiluminescence ultra-rapides. Nous présentons alors les résultats de nos expériences dans des compositions de propane ou d’éthane et d’oxygène à la pression et à la température initiales 200 mbar et 290 K. Nous avons considéré des distributions monotones, de richesse décroissante, et des distributions non-monotones, de richesse décroissante puis croissante. Dans les distributions monotones, nous avons identifié deux types d’extinction de la détonation, l’un brusque, par découplage choc-flamme, pour des gradients suffisamment forts, l’autre progressif, par transition vers des modes marginaux de propagation, pour des gradients plus faibles. Nous avons proposé et validé des critères d’existence de la détonation fondés sur les échelles caractéristiques du problème. Nous avons démontré, pour ces distributions, la capacité de simulations numériques avec cinétique chimique détaillée à représenter nos expériences, dans le cadre d’une collaboration avec l’Université Keio. Dans les distributions non-monotones, nous avons identifié des comportements super-critique, critique et sous-critique, selon que la détonation est transmise ou non de la zone où la richesse diminue vers celle où elle augmente. Nous avons en particulier identifié les conditions de réamorçage d’une détonation éteinte dans la zone de richesse décroissante. Notre étude souligne l’intérêt de travaux futurs sur des non-uniformités de compositions initiales constitués de gaz brûlés et de gaz frais et donc, également, des non-uniformités de température initiale. Elle souligne aussi la nécessité de diagnostics optiques et d’outils numériques performants, et de schémas détaillés de cinétique chimique adaptés aux hautes pressions et températures caractérisant la dynamique des détonations. / Our study is an experimental and numerical work on the dynamical behaviours of detonation waves in non-uniformly distributed premixed gases with composition gradients parallel to the direction of the detonation propagation. The study aims at improving the understanding of the complex phenomena involved in the combustion chambers of pulsed or rotating detonation engine (PDE, RDE) and after accidental leaks of fuels. We first remind the context of our study, the phenomenology of gaseous detonation and the previous works on detonation propagation in non-uniform compositions. We then describe the experimental set-up that we have designed in order to meet the constraint of a controlled generation of composition gradients in a 50⇥50 mm2 square-section, 665-mm length test chamber, and the diagnoses that we have implemented : oxygen probes, fast pressure transducers, carbon-sooted plates and ultrafast Schlieren and chemiluminescence spectroscopy. Next, we present the results of our experiments in mixtures of propane or ethane and oxygen with initial pressure and temperature 200 mbar and 290 K, respectively. We have considered monotonic distributions, with decreasing equivalence ratio, and non- monotonic distributions, with decreasing then increasing equivalence ratio. In the monotonic distributions, we have identified two types of detonation quenching, one sudden, with a shock-flame decoupling, for the steeper gradients, the other progressive, with a transition through marginal modes of detonation propagation, for the weaker gradients. We have proposed and validated criteria for detonation, based on the characteristic scales of the problem. We have demonstrated, for these monotonic distributions, the ability of numerical simulations with detailed schemes of chemical kinetics to represent our experimental observations, through a collaboration with Keio University. In the non-monotonic distributions, we have identified super-critical, critical and sub-critical behaviours, depending on whether the detonation is transmitted or not from the domain where the equivalence ratio decreases to that where it increases. In particular, we have identified the re-initiation conditions for a detonation that was quenched in the domain of decreasing equivalence ratio. Our study stresses the interest for future works to consider non-uniform distributions of mixtures comprising burnt gases and fresh reactants, and, consequently, non-uniform distributions of temperature. It also stresses the need for performing optical diagnoses and numerical capacities and for detailed schemes of chemical kinetics adapted to the high pressures and temperatures characterizing detonation dynamics.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / The yellow-cardinal (Gubernatrix cristata) is a passerine bird that occurs in southern Brazil, especially along the border with Uruguay and Argentina. It is an endangered bird and your population is decreasing due to loss and fragmentation of your habitats besides illegal capture. In Brazil, its captive breeding is regulated by the government agency and allows the maintenance of individuals in different places with different breeding systems. Among the parasites that affect passerines, the coccidia of the genus Isospora are the most easily found in both captive and free-living birds. Commonly cause injury to the intestinal tissue and could occasionally affect other organs. In this work, we describe a new species of Isospora in yellow-cardinal and also establish the occurrence of the protozoan and its relationship with factors such as sex, use of parasiticide products, type of cage, contact with feces, food type and frequency of cleaning in birds kept in captivity in the city of Santa Maria, Rio Grande do Sul, Brazil. / O cardeal-amarelo (Gubernatrix cristata) é um pássaro que ocorre no sul do Brasil, principalmente na fronteira com Uruguai e Argentina. É uma ave ameaçada de extinção e sua população está decrescendo devido a perda e fragmentação do seu habitat além da captura ilegal. No Brasil sua criação em cativeiro é regulamentada pelo órgão governamental e possibilita a manutenção dos indivíduos em vários locais com diferentes sistemas de criação. Os coccídeos do gênero Isospora estão entre os mais encontrados na ordem Passeriformes, tanto em aves cativas quanto em aves de vida-livre. Comumente causam injúrias no tecido intestinal, podendo ocasionalmente afetar outros órgãos. Neste trabalho pôde-se descrever uma nova espécie de Isospora em cardeais-amarelo e também estabelecer a ocorrência deste protozoário e relacionar com fatores como sexo, uso de produtos parasiticidas, tipo de recinto, contato com fezes, tipo de alimentação e frequência de limpeza dos recintos nas aves mantidas em cativeiro na cidade de Santa Maria, Rio Grande do Sul, Brasil.

The purpose of this study was to evaluate the effectiveness of video modeling of contingencies alone and/or combined with direct exposure to the contingencies in the treatment of food selectivity. Treatment procedures included sequentially introducing videos in which models consumed nonpreferred food, were exposed to differential reinforcement, or exposed to escape extinction and differential reinforcement. In addition, participants were exposed to differential reinforcement. Results indicated video modeling of differential reinforcement plus differential reinforcement may be effective at increasing consumption of some nonpreferred foods, but the results were not replicated across all foods. For one participant, consumption of one food increased with video modeling alone.

We characterize the absolute magnitudes and colors of RR Lyrae stars in the globular cluster M5 in the ugriz filter system of the Dark Energy Camera (DECam). We provide empirical period-luminosity (P-L) relationships in all five bands based on 47 RR Lyrae stars of the type ab and 14 stars of the type c. The P-L relationships were found to be better constrained for the fundamental-mode RR Lyrae stars in the riz passbands, with dispersions of 0.03, 0.02 and 0.02 mag, respectively. The dispersion of the color at minimum light was found to be small, supporting the use of this parameter as a means to obtain accurate interstellar extinctions along the line of sight up to the distance of the RR Lyrae star. We found a trend of color at minimum light with a pulsational period that, if taken into account, brings the dispersion in color at minimum light to <= 0.016 mag for the (r - i), (i - z), and (r - z) colors. These calibrations will be very useful for using RR Lyrae stars from DECam observations as both standard candles for distance determinations and color standards for reddening measurements.

Type Ia supernovae (SNe Ia) have proven to be extremely useful for measuring cosmological distances and were used for the discovery of the accelerated expansion of the universe. Although thousands of SNe Ia have been observed to date, many questions surrounding the physics of the explosions and the nature of their progenitor systems remain unanswered. An notable property of many SNe Ia is the relation between extinction due to dust and their colour. For example SN 2014J, the nearest SN Ia in recent years, has an extinction relation which would be very unusual to observe in the Milky Way. One possible explanation to the peculiar extinction could be the presence of circumstellar (CS) dust surrounding the explosions. Incidentally, some proposed progenitor models of SNe Ia suggest that the explosions are surrounded by shells of matter, which could account for the unusual extinction. CS gas would be ionised, if it is exposed to the intense ultraviolet (UV) radiation of a SN Ia. The research presented in this thesis focuses on the search for CS gas by observing the effects of photoionisation on absorption lines commonly detected in optical spectra. Simple models suggest that the frequently studied sodium doublet (Na I D) should significantly decrease or even disappear if the gas is in the CS environment. Conversely, the absence of variations implies that the absorbing gas clouds must be far from the explosion, in the interstellar medium (ISM). To date, few SNe Ia have been shown to have variable absorption lines, to which we have added another case with SN 2013gh. Yet, we have also shown that most observations searching for variable absorption lines have been taken at too late phases, when most CS gas will have already been ionised. Setting out to obtain the earliest possible coverage of a SN Ia with high-resolution spectra, we have been able to set strong limits on the presence of CS gas surrounding SN 2017cbv. Along with evidence from other observational methods, these results have shown that there is little matter in the CS environments of SNe Ia, suggesting that the peculiar extinction likely results from the dust properties of their host galaxy ISM. Although the progenitor question cannot be resolved by these observations, nondetections of CS gas point to models which do not deposit large amounts of matter in their surroundings. / <p>At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 5: Submitted.</p>

Abstract There are more small-bodied species of birds than those having large bodies. Generally, and relative to occurrance in any one place, small-bodied species also contain more individuals than large-bodied species. The same patterns have been documented for several groups of higher organisms for example, snakes, flowering plants and mammals, which suggests that there exists a general reason "why", which applies to other groups of species as well as to birds. This thesis attempts to identify this reason. In the first place, it is possible that most species happened to become small-bodied by chance. Simulations of neutral body-size evolution indicate however that the observed bias towards small size is stronger than that accounted for by neutral evolution. Then, the most plausible explanation for why most species are small is that small-bodied species speciate faster. However, statistical analyses accounting for historical relatedness of present-day species indicate no relation between body size and the rate of speciation. Finally, instead of little by little, the dominance of small species may have arisen suddenly, when approximately 65 million years ago (presumably) a large meteorite hit the earth, causing mass extinctions. However, analysis of body sizes and genetic differences of extant species reveals that while avian species numbers were approximately halved, the catastrophe affected small and large species equally. Thus, the reason why most species are small does not seem to be due to differential rates of speciation or extinction. Instead, the cause appears to be in the tempo and mode of evolution. It was found by analysis of extant species' body size that probably most differences in body size between species arise at the moment of speciation. Differences between small-bodied species are smaller than between large-bodied species and probably this difference also has its origin at the moment of speciation. Consequently, groups of small species stay small whereas groups of large species are more variable in body size, so that in the end most species are small. / Tiivistelmä Maailman noin 10 000 lintulajin joukossa pienikokoisia lajeja on enemmän kuin suurikokoisia. Yleensä pienkokoiset lajit ovat myös yksilömääriltään suurempia kuin samalla paikalla esiintyvät suurikokoiset lajit. Koska sama ilmiö on havaittu monissa muissa suurissa eliöryhmissä (esim. nisäkkäät, käärmeet ja kukkakasvit), on ilmeistä, että on olemassa yhteinen syy, joka pätee niin linnuissa kuin muissakin eliöryhmissä. Tämän väitöskirjan tavoite on selvittää, mikä tämä yhteinen syy voisi olla. Ensinnäkin on mahdollista, että suurin osa lajeista on kehittynyt pienikokoisiksi aivan sattumalta. Ruumiin koon evoluution simulaatiot kuitenkin osoittavat, että on hyvin epätodennäköistä, että neutraali evoluutio olisi johtanut pienikokoisten lajien suuriin määrään havaitussa määrin. Toinen mahdollinen selitys ilmiölle on, että pienikokoiset lajit lajiutuvat nopeammin. Tilastolliset analyysit, jotka ottavat huomioon nykyisin elävien lajien sukulaisuussuhteet, osoittavat ettei ruumin koon ja lajiutumisen vauhdin välillä ole yhteyttä. Kolmas mahdollinen selitys pienikokoisten lajien suurelle määrällä on historiallinen. On mahdollista, että pienikokoisten lajien suhteellisen suuri määrä syntyi nopeasti noin 65 miljoonaa vuotta sitten tapahtuneen massasukupuuton seurauksena, joka fossiiliaineiston perusteella kohdistui erityisesti suurikokoisiin maaeläimiin (esimerkiksi dinosauruksiin). Vertaileva analyysi nykyään elävien lintulajien ruumiin koosta ja geneettisistä eroista osoittaa, että vaikka suuri osa lintulajeista hävisi massasukupuutossa, tämä katastrofi karsi lajeja riippumatta niiden ruumiin koosta. Näyttää siis siltä, etteivät erot lajiutumisen tai sukupuuttojen esiintymisessä selitä sitä, että suurin osa lajeista on pienikokoisia. Tämän tutkimuksen tulosten perusteella syy näyttäisi sen sijaan olevan ruumiin koon kehityksen vauhdissa ja siinä tavassa, jolla kehitys yleensä etenee. Analyysi nykyisten lajien ruumiin koosta paljasti, että suurin osa eroista lajien välillä syntyy (evolutiiviessa aikataulussa) suhteellisen nopeasti lajiutumistapahtuman yhteydessä (punktualismi) eikä vähitellen pitkien aikojen kuluessa (gradualismi), kuten yleensä oletetaan. Kehityslinjojen sisällä pienikokoisten lajien väliset erot ruumiin koossa olivat pienempiä kuin isokokoisten lajien väliset erot - ja todennäköisesti myöskin tämä ero syntyy lajiutumisen yhteydessä. Tämä johtaa evoluution kuluessa tilanteeseen, että alunperin pienikokoisista lajeista kehittyneet lajit ovat myös pienikokoisia, kun taas isokokoisten lajien kehityslinjoissa on nähtävissä huomattavasti paljon enemmän vaihtelua ruumiin koossa. Näiden seurauksena eliöstöissä suurin osa lajeista lopulta on pienikokoisia.

The purpose of this study was to compare response rates and resistance to extinction in single-task and multiple-task phases. Research was conducted with thirty undergraduate college students in a controlled experimental setting. Each Participant was exposed to 4 treatment phases: single-task, fixed-ratio of one (ST-FR1), multiple-task fixed-ratio of one (MT-FR1), single-task fixed-ratio of 5 (ST-FR5) and multiple-task fixed-ratio of 5 (MT-FR5) all beginning with a baseline phase and reverting back to baseline after the first two conditions were presented. Half of the Participants received the single-task phase first, and the other half received the multiple-task phase first, in order to observe the behavior in transition. A trials-to-criterion measure was used to determine how long it took each Participant’s behavior to adapt to the new contingency in the next phase, which was presented without any signal. The data reveal that regardless of the order of phase presentation it took Participants more than twice as long to reach the criterion in the single-task phases, than in the multiple-task phases.

The mechanisms underlying cannabinoid impairment of fear memory is not clear. This study investigated the effects of the synthetic cannabinoid HU210 and the endocannabinoid hydrolysis inhibitor JZL 195 on fear memory following contextual fear conditioning (CFC; an animal model of fear). The long-term depression (LTD)-blocking peptide Tat-GluR2 was utilized to investigate whether the expression of cannabinoid-induced LTD (CB-LTD) is required for the cannabinoid impairment of acquisition and consolidation of contextual fear memory. HU210 reduced freezing throughout the test phase of the acquisition protocol, which was not affected by pre-administration of Tat-GluR2. High and moderate doses of HU210 reduced freezing during the first and last half, respectively, of the test phase of the consolidation protocol, which was prevented by pre-treatment with Tat-GluR2. HU210 did not affect freezing during the test phase of the retrieval protocol. Thus, these results suggest that HU210 impairs acquisition and consolidation, but not retrieval of contextual fear memory, and that in vivo CB-LTD expression is required for HU210 impairment of the consolidation, but not acquisition, of contextual fear memory. We also observed that HU210 and JZL 195 do not facilitate the acquisition of contextual fear memory extinction.

Abstract Dissimilatory microbial sulfate reduction (MSR) The specific objectives of the study were to provide the first measurements of sulfur isotope fractionation associated with acidophilic sulfate reducing-microorganisms, and to examine whether pH influences sulfur fractionation during MSR. The fractionation associated with the strains investigated was comparable to that of neutrophilic strains with similar metabolisms (4-12‰), but varied with pH. Two fractionation regimes were identified: one regime is consistent with fractionation during exponential growth, while the other – not identified previously - is not linked to active sulfate reduction and may result from internal sulfate accumulation. This would represent the first measurement of sulfur fractionation during sulfate uptake, the first step of MSR. Geological processes at the Cretaceous-Paleogene (KPg) boundary The KPg boundary is associated with one of the largest biological extinctions in the history of our planet. Two major geologic events - the Chicxulub bolide impact with evaporite terrane and the eruption of the Deccan continental flood basalts - coincide with the KPg boundary and have been identified as possible triggers for the extinctions, but their relative timing remains unresolved. The objectives of this study were to identify the contribution of these processes to the sulfur burden in the sedimentary environment of two freshwater KPg sections, and to determine their relative timing. The results demonstrate that the peak of Deccan volcanism post-dates the Chicxulub impact and the associated abrupt KPg mass extinction, thus precluding a direct volcanic causal mechanism, but shedding light on the underlying causes for the delayed recovery of ecosystems in the early Paleogene.

Monomeric red fluorescent proteins (RFPs) are used extensively for applications in molecular biology research, and are especially suited for whole body imaging applications due to their longer excitation and emission wavelengths, which are less damaging and penetrate deeper into animal tissue. However, these proteins suffer from reduced brightness compared to other fluorescent proteins, and require further engineering, which is often achieved through random methods, incurring large time and resource costs. Here we propose a rational design approach to improve the quantum yield of RFPs by reducing conformational variability of the chromophore. We engineered mRojoA, a mutant containing a π-stack involving Tyr197 and the chromophore phenolate, to include the P63F/H/Y mutations on its other side, by simultaneously mutating neighbouring positions 16, 143, and 163. The brightest mutants that we found in each library, mRojo-VYGV, mRojo-VFAV, and mRojo-VHSV, exhibited 1.8- to 2.4-fold increases in brightness, and quantum yield increases of up to 2.1-fold. In all three mutants, the increases in brightness were predominantly due to improvements in the quantum yield and not the extinction coefficient. Solving the crystal structures of two of these mutants along with a dim variant allowed us to strongly infer a link between rigidity of the chromophore and increased quantum yield. In addition, back-mutating position 63 in the highest quantum yield mutant, mRojo-VYGV, reversed the improvement in quantum yield, indicating that Y63 was the primary residue responsible for the improved brightness of the protein. Unfortunately, the mCherry-VYGV mutant did not achieve a similar increase in quantum yield or brightness. This is likely due to the lack of a second bulky aromatic residue at position 197, which is present in mRojoA. Nevertheless, this rational approach could be applied to some other RFPs whose chromophores exhibit increased conformational variability in order to further improve their brightness.