A assimetria de cinco estruturas corporais da mosca-das-frutas Ceratitis capitata foi analisada para uma avaliação se poderiam ser utilizadas como bioindicadores. As análises foram feitas em amostras de uma população natural e de uma população de laboratório. Adicionalmente, em amostras obtidas da população de laboratório, os índices de assimetria foram avaliados após a submissão das diferentes amostras à diferentes temperaturas. No estágio de pupa, as amostras foram tratadas nas temperaturas de 17, 20, 25 e 30oC. As estruturas analisadas, em machos e fêmeas foram as cerdas frontais (FO), orbitais (OB), pós-oculares (PO), o comprimento e largura das asas. Nos machos, além dessas estruturas, foi incluída a análise do comprimento de uma das cerdas orbitais, a supra-fronto-orbital (SFO), que apresenta dimorfismo sexual. A variação numérica das cerdas FO e OB foi muito baixa em todas as amostras, não permitindo uma análise da assimetria. A assimetria das demais características, tanto merísticas como métricas, mostrou ser compatível com o modelo da assimetria flutuante (AF). O grau de assimetria de cada estrutura não diferiu entre machos e fêmeas, mas foi significativamente mais alto na amostra da população de laboratório do que na amostra da população natural. No entanto, a assimetria holística (somatória da AF das diferentes estruturas) não mostrou diferenças entre as duas amostras. Nas amostras submetidas a diferentes temperaturas foram observadas alterações significativas no grau de assimetria das estruturas, mas nenhuma alteração no tipo de assimetria que continuou sendo caracterizada como flutuante. Essas análises mostraram não haver diferenças entre os sexos, nem interações entre sexo e temperatura, mas apenas diferenças significativas entre as temperaturas. A assimetria flutuante das cerdas pós-oculares aumenta com o elevação da temperatura, a AF do comprimento das asas e da cerda SFO (nos machos) não mostra correlação com as temperaturas e os resultados indicam que a AF da largura das asas é mais elevada nas temperaturas extremas que nas intermediárias. A comparação da assimetria holística entre as amostras das diferentes temperaturas mostrou que as diferenças não foram significativas. Os resultados indicam que a assimetria das 52 cerdas pós-oculares e das medidas do largura das asas apresentam potencial para evidenciar eventuais estresses durante o desenvolvimento desses insetos. Indicam, também, que a utilização de uma assimetria holísitca pode mascarar possíveis diferenças da assimetria flutuante de estruturas individuais. / Asymmetry of five traits of the fruit fly Ceratitis capitata, an introduced insect pest in Brazil, was analysed in order to evaluate if they present potencial to be used as bioindicators of the \"quality\" of these insects. Samples from a natural population and from a laboratory colony were studied. Moreover, asymmetry was measured in samples from the laboratory colony maintained during the pupal stage, in the temperatures of 17, 20, 25 and 30oC. The analysed traits of males and females, were the frontal, the orbital and the postocular bristles, measurement of the length and cross diameter of the wings and the length of the supra-frontoorbital bristles in the males that show a pronounced sexual dimorphism. Since the numerical variation of the frontal and orbital bristles was very low in all samples it was not possible to analyse the variation in terms of asymmetry. For all other traits, meristic or metric, asymmetry was characterized as following the fluctuating asymmetry (AF) model. AF of the different traits does not differ between sexes, but was significantly higher in the laboratory sample than in the sample from the natural population. No significant differences, however, were found in the holistic asymmetry (sum of AF of different traits) between the two samples. In relation to the experiments conducted in different temperatures, no variations in AF levels were observed between sexes, nor interactions between sex and temperatures. However, significant differences were observed among the samples submitted to different temperatures. AF of the postocular bristles increases proportionaly to the increment of the temperature, while AF of wings and supra-fronto-orbital bristles (in males) lengths showed no correlations with the temperatures, and AF of the cross diameter of wings seems to be higher at the extreme temperatures than at the intermediate ones. When a holistic AF was applied, no significant differences among the temperature samples were observed. The results indicate that asymmetry of the postocular bristles and the length of the wings are parameters showing potencial use as indicators of stresses during development of these insects. They also indicate that a holistic asymmetry may mask variations in the asymmetry of individual traits.

Les mousses liquides soumises à du cisaillement présentent une très grande viscosité, mais l'origine locale de la dissipation se produisant pendant cette déformation est encore mal comprise. Dans le but d'apporter quelques éléments de réponses à cette importante question ouverte, notre travail décrit le comportement observé sur quelques films connectés lorsqu'une déformation leur est appliquée. Nous avons créé un montage permettant de fabriquer un pattern élémentaire de mousse, et de modifier la taille de chaque film en contrôlant la géométrie du cadre qui le supporte. Ce montage original, auquel s'ajoute une combinaison d'appareils optiques, nous permet de révéler les processus se produisant dans le film, notamment la compétition entre son allongement ou compression, et l'extraction d'un nouveau film depuis les ménisques raccordant les films. Nous montrons de plus que cette compétition dynamique dans un film donné est affectée par la déformation de ses premiers et seconds films voisins. La géométrie particulière du montage nous a également permis de découvrir et de décrire pour la première fois une instabilité gravitationnelle se produisant lorsqu'un film épais se situe au-dessus d'un film plus mince. Nous avons mesuré la longueur d'onde de l'instabilité et l'avons comparée à des prédictions théoriques en régime linéaire. Ces différents écoulements affectent la distribution d'épaisseur dans le film, et peuvent ainsi jouer un rôle important sur la viscosité ou sur la stabilité des mousses 3D. Finalement, le montage utilisé pourra s'avérer utile à l'avenir comme rhéomètre de films liquides. / Liquid foams under shearing exhibit a large effective viscosity, and the understanding of the local origin of the dissipation occurring during deformation is unknown. In the aim to contribute to this important open problem, we tried to describe the behavior of a few connected films under deformation. We created a setup allowing to make an elementary foam sample and to modify each film size by controlling the shape of the deformable frame supporting the films. This original setup together with a combination of optical devices allowed us to reveal processes happening in the film, and especially the competition between film stretch or compression, and extraction of a new film from the menisci connecting the films. Importantly, we show that this dynamical competition in a given film is affected by the deformation of its first and even second neighbors. The unique geometry of the setup gave us the opportunity to discover and describe for the first time a gravitational instability which takes place when a thicker film is on top of a thinner one. We measured the wavelength and compared it to theoretical predictions in the linear regime. These different flows affect the thickness distribution, and may thus play an important role in the viscosity or in the stability of 3D foams. As a perspective, the designed setup could prove to be useful as a liquid film rheometer.

Low swirl burners (LSBs) have gained popularity in heating and gas power generation industries, in part due to their proven capacity for reducing the production of NOx, which in addition to reacting to form smog and acid rain, plays a central role in the formation of the tropospheric ozone layer. With lean operating conditions, LSBs are susceptible to combustion instability, which can result in flame extinction or equipment failure. Extensive work has been performed to understand the nature of LSB combustion, but scaling trends between laboratory- and industrial-sized burners have not been established. Using hydrogen addition as the primary method of flame stabilization, the current work presents results for a 2.54 cm LSB to investigate potential effects of burner outlet diameter on the nature of flame stability, with focus on flashback and lean blowout conditions. In the lean regime, the onset of instability and flame extinction have been shown to occur at similar equivalence ratios for both the 2.54 cm and a 3.81 cm LSB and depend on the resolution of equivalence ratios incremented. Investigations into flame structures are also performed. Discussion begins with a derivation for properties in a multicomponent gas mixture used to determine the Reynolds number (Re) to develop a condition for turbulent intensity similarity in differently-sized LSBs. Based on this requirement, operating conditions are chosen such that the global Reynolds number for the 2.54 cm LSB is within 2% of the Re for the 3.81 cm burner. With similarity obtained, flame structure investigations focus on flame front curvature and flame surface density (FSD). As flame structure results of the current 2.54 cm LSB work are compared to results for the 3.81 cm LSB, no apparent relationship is shown to exist between burner diameter and the distribution of flame surface density. However, burner diameter is shown to have a definite effect on the flame front curvature. In corresponding flow conditions, a decrease in burner diameter results a broader distribution of curvature and an increased average curvature, signifying that compared to the larger 3.81 cm LSB, the flame front of the smaller burner contains tighter, smaller scale wrinkling.

Large-eddy simulations of turbulent flows past a circular cylinder have been performed at sub-, critical and super-critical Re using an orthogonal curvilinear grid solver, CFDship-Iowa version 6.2. An extensive verification and validation study has been carried out. Various aspects of the flow field have been investigated. The aspect ratio of the computational domain has major effects on the results. In general, large aspect ratio produced best results for the sub-critical Re. Small dependency on both aspect ratio and grid resolution was observed for the critical Re. Small aspect ratio and conservative scheme produced best results for the super-critical Re. Overall flow features and the drag crisis phenomenon have been correctly predicted. A lot of experimental and numerical studies of flow past a circular cylinder were collected and used for the validation of the present LES study. Integral and local variables were in fairly good agreement for the sub-critical Re. Sharp behavior including drag crisis was predicted for the critical Re. Although some discrepancy including early formation of turbulent separation was observed, local flow structures including separation bubble were observed for the super-critical Re. The formation of secondary vortex near the cylinder wall and its evolution into separation bubble were observed. The spectral analysis showed that the separation bubble had the instabilities close to the shear layer frequency. The proximity of shear layer to the cylinder enhanced the mixing process of boundary layer and shear layer and led to the formation of separation bubble. A snapshot POD method was used to extract flow structures in the boundary layer, shear layer and wake. In the boundary layer, the secondary vortices and separation bubble were successfully extracted. Due to the weak TKE distribution, specific flow structures were hard to find in the shear layer. Large two-dimensional flow structures representing the Karman shedding vortices were extracted for the sub- and super-critical Re.

The current research focuses on the thermoacoustic instability of lean premixed combustion, which is a promising technique to inhibit Nitrogen Oxides (NOx) emission. Thermoacoustic instability describes the condition that the pressure oscillation is unusually high in the combustion device. It results from the coupling between pressure fluctuation and heat release oscillation, which experiences significant temporal and spatial variations. These variations are closely related to the flame shape deformation and critical in determining the trend of the global instability. Therefore, the current study aims to examine both the global and local flame features created by thermoacoustic instability. The first part of the work is studying the unstable flame induced by artificial acoustic perturbation. The particular focus is on the global and local heat release rate oscillation. In the experiment, the global heat release rate oscillation was indicated by the hydroxyl (OH*) chemiluminescence captured with a photomultiplier tube (PMT). On the other hand, the flame shape and the local mean heat release rate were examined with flame surface density (FSD), which was calculated with the images captured with the planar laser-induced fluorescence of the hydroxide radical (OH-PLIF) method. The main analysis methods used in the current research are Rayleigh criterion and proper orthogonal decomposition (POD), which can efficiently capture the dominant oscillation mode of the flame. The acoustic perturbation study first examined the effect of pressure variation (0.1 - 0.4 MPa) on the flame response to the acoustic perturbation. Results show that the elevated pressure intensifies the fundamental mode of heat release oscillation when the heat release oscillation is in phase with the pressure fluctuation; otherwise, the fundamental oscillation tends to be inhibited. The pressure affects both the strength and the distribution of the local fundamental and the first harmonic oscillations. Furthermore, the effect of the pressure on the distribution is larger than that on the strength. The study also investigated the role of Strouhal numbers in characterizing the flame oscillation induced by acoustic perturbation. Results show that the Strouhal number can characterize the changing trend of the oscillation amplitude, whereas the oscillation phase-delay is less dependent on the Strouhal number. The local analysis reveals that the nonlinear flame behavior results from the flame rollup induced by acoustic perturbation. Furthermore, the reconstruction of the global heat release shows that the cancellation of out-of-phase local oscillations can cause a low-level global oscillation. Results also demonstrate that the local heat release oscillation contains intense harmonic oscillations, which are closely associated with the flame rollup. However, the harmonic oscillation is less likely the main reason causing nonlinear flame behavior. Besides the study with acoustic perturbation, the current study also conducted experimental and modeling studies on the self-excited thermoacoustic instability. The particular focus is examining the effects of hydrogen addition on the instability trend. Results demonstrate that the hydrogen concentration can affect both the oscillation frequency and amplitude. Pressure analysis shows that the low-frequency mode is triggered when the hydrogen concentration is low, whereas a high hydrogen concentration tends to excite a high-frequency mode. Moreover, the frequency tends to increase with an increasing hydrogen concentration. Modeling results illustrate that the change of the oscillation mode, which is determined by the turbulent flame speed, is mainly affected by the delay time between the heat release oscillation and the velocity fluctuation. The modeling work shows that the one-dimensional model is not very efficient in capture the instability trend of the high-frequency mode. It may result from the lack of the knowledge of the mechanism of acoustic damping and flame dynamics.

Dans ce travail, nous étudions l'écoulement au sein d'un canal symétrique avec une expansion et une contraction soudaines. Cette configuration peut être considérée comme constituée de deux cavités face à face, deux cavités en miroir, que nous dénommons "double cavité". Le sujet est traité expérimentalement, numériquement et analytiquement, en faisant varier la vitesse d'entrée et de la distance entre cavités, mais en restant à des nombres de Reynolds modérés. L'accent est mis sur l'interaction entre les deux couches de cisaillement et sur le mécanisme de rétroaction intracavitaire dans la limite des écoulements incompressibles. Expérimentalement, on mesure la vitesse par Vélocimétrie par Images de Particules non résolue en temps (PIV 2D2C) dans un plan longitudinal permettent de quanti er le champ de vitesse en moyenne temporelle. Par ailleurs, des mesures par Vélocimétrie Laser à effet Doppler (LDV) et des mesures résolues en temps par PIV 2D2C permettent d'accéder à la composition spectrale des fluctuations de vitesse dans la direction de l'écoulement. L'écoulement est caractérisé à partir des séries temporelles, enregistrées dans les couches de cisaillement d'une des deux cavités, pour une large gamme de vitesses d'entrée et des distances entre cavités. Des simulations numériques directes 2D et 3D, permettent d'étudier le mécanisme hydrodynamique de rétroaction intracavitaire, à partir des champs de vitesse complet. Le champ de vorticité issu des simulations numériques 2D montre l'importance de la rotation d'ensemble au sein de la cavité qui transporte les injections de vorticité induites par les oscillations de la couche de mélange conduisant à une structure de type "carrousel" elle-même à l'origine du mécanisme de rétroaction responsable des oscillations auto-entretenues de la couche de cisaillement. La quanti cation des temps caractéristiques de cette rotation permet d'identifier le régime dans lequel se trouve l'écoulement. Une analyse de stabilité en temps seul, ainsi qu'en temps et espace est réalisée pour des écoulements non visqueux, en prenant un écoulement de base unidimensionnel pour chacun des cas: cavité simple ou double. Pour prendre en compte l'extension finie du système, dans le cas de l'analyse de stabilité linéaire spatio-temporel, on ajoute la condition dite de Kulikowskii, qui permet de prendre en compte la réflexion des ondes d'instabilité hydrodynamique aux bornes du domaine de la cavité. Ce mécanisme de rétroaction produit un ensemble discret de fréquences non-harmoniques, dont certaines correspondent effectivement aux données expérimentales. / This work investigates the flow in a symmetric channel with a sudden expansion and contraction, creating two facing cavities, a so called double cavity. Double cavity flow at moderate Reynolds numbers is studied experimentally, numerically and analytically, as the inflow velocity and the distance between the cavities are varied. The focus is put on the interaction of the two shear layers and the intracavitary hydrodynamic feedback in the incompressible limit.Experimentally, standard 2D2C particle image velocimetry (PIV) measurements in a given spanwise plane provide information on the instantaneous and mean velocity flow fields. Laser Doppler velocimetry and time resolved 2D2C PIV measurements reveal the richness of the streamwise fluctuating velocity spectra. The flow is characterized based on times series, recorded in one of the cavity's shear layers, for a wide range of inflow velocities and cavity distances.Two dimensional and three dimensional direct numerical simulations, which give easy access to the entire flow field, are used to study the intracavitary hydrodynamic feedback mechanism. Vorticity fields, obtained from 2D numerical simulations, show the importance of the recirculating intracavitary back flow. Vorticity packages, injected by the oscillating and impinging shear layer at the downstream cavity edge, are advected upstream in the recirculation region, creating a ``carousel-like'' pattern. The interaction of this vortex carousel with the oscillating shear layer is found to be responsible for the self-sustained oscillations observed experimentally in single and double cavity flow. The quantification of three characteristic time scales of the rotation allows to identify in which regime the flow resides.Temporal and spatio-temporal inviscid linear stability analyses are applied to a one dimensional base flow of single and double cavity flows. To account for the finite extent of the system, the spatio-temporal linear stability analysis is conditioned by a so called Kulikowskii condition, which allows the reflection of hydrodynamic instability waves within the cavity domain. This feedback mechanism yields a set of discrete, non-harmonic frequencies, some of which compare well with experimental results.

Thesis advisor: Shanta Pandey / Thesis advisor: Paulette Landon / Homeless women in Chile live in high-risk situations; however, little research exists about how they face homelessness. This dissertation helps address this information gap through the inquiry into the question about what are the pathways to homelessness of homeless women in Chile? For this, a mixed-method research design has been used. The quantitative data were obtained from the Annex Questionnaire for homeless people of the Social Registry of Household, Government of Chile, updated to March 31, 2019, while the Qualitative information was obtained by conducting in-depth interviews with 4 homeless women and professionals who have worked with them in the context of their participation in social programs. The findings showed three main results: (1) The paths to homelessness for women in Chile begins with residential instability and individual adjustment to deal with it. (2) Residential instability transforms into homelessness through an extended accumulation of disadvantages and loss of significant resources and social networks. (3) Women's homelessness, even though it may become permanent or chronic, is cyclical with many entries and exits within a permanent context of residential instability. / Thesis (PhD) — Boston College, 2020. / Submitted to: Boston College. Graduate School of Social Work. / Discipline: Social Work.

We investigate the Richtmyer-Meshkov instability (RMI) that occurs when an incident shock impulsively accelerates the interface between two different fluids. RMI is important in many technological applications such as Inertial Confinement Fusion (ICF) and astrophysical phenomena such as supernovae. We consider RMI in the presence of the magnetic field in converging geometry through both simulations and analytical means in the framework of ideal magnetohydrodynamics (MHD). In this thesis, we perform linear stability analyses via simulations in the cylindrical geometry, which is of relevance to ICF. In converging geometry, RMI is usually followed by the Rayleigh-Taylor instability (RTI). We show that the presence of a magnetic field suppresses the instabilities. We study the influence of the strength of the magnetic field, perturbation wavenumbers and other relevant parameters on the evolution of the RM and RT instabilities. First, we perform linear stability simulations for a single interface between two different fluids in which the magnetic field is normal to the direction of the average motion of the density interface. The suppression of the instabilities is most evident for large wavenumbers and relatively strong magnetic fields strengths. The mechanism of suppression is the transport of vorticity away from the density interface by two Alfv ́en fronts. Second, we examine the case of an azimuthal magnetic field at the density interface. The most evident suppression of the instability at the interface is for large wavenumbers and relatively strong magnetic fields strengths. After the shock interacts with the interface, the emerging vorticity breaks up into waves traveling parallel and anti-parallel to the magnetic field. The interference as these waves propagate with alternating phase causing the perturbation growth rate of the interface to oscillate in time. Finally, we propose incompressible models for MHD RMI in the presence of normal or azimuthal magnetic field. The linearized equations are solved numerically using inverse Laplace transform. The incompressible models show that the magnetic field suppresses the RMI, and the mechanism of this suppression depends on the orientation of the initially applied magnetic field. The incompressible model agrees reasonably well with compressible linear simulations.

Bangladesh RMG (Ready-made garments) industry has grown rapidly and contributing to country’s economy successfully for last three decades. In 2018-2019 this giant sector contributed 84% of the total foreign exchange earnings of the country. This is the unique sector of the country in terms of significant export growth rate and stands as the second-largest RMG exporter with 6.8% market share according to world trade organization 2019. Though the growth rate is increasing annually but it seems the growth of the industry yet to reach highest potentials. Aim: Aim of this study is to understand the factors influencing the sustainable development of Bangladesh ready-made garments industry.   Method: The study has been conducted applying the qualitative method. Primary data is collected through interviewing suppliers of the ready-made garments of Bangladesh. Secondary data sources were governmental and private organization’s websites. The data were analyzed by comparing it with existing literature.  Results: The result shows factors such as Compliance, Political unrest, Technology, Research & Development, Diversifications, Competition, Marketing strategy influencing sustainable development of the ready-made garments industry of Bangladesh.  Contributions of the study: This study investigates the factors hindering sustainable development of the Bangladesh read-made garments sector which has been discussed in previous literature in a segregated way. In this study factors that cause unstable export growth and hinder sustainable development have been addressed in the same frame. Furthermore, stakeholders of the company (Customer, Suppliers, Buyers, Investors, and Government) will be benefited to know the results of this study, as sustainable development is the result of unified efforts.  Suggestions for further research: Future researchers can investigate the factors elaborately both from suppliers and buyers’ point of view. Because of limitations, author could not reach more suppliers and buyers. The buyer’s prospect is also important to judge the factors influencing growth instability and sustainable development.

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第21990号 / 医博第4504号 / 新制||医||1037(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 武藤 学, 教授 松田 文彦, 教授 小川 誠司 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM