It is now well established that stellar winds of hot stars are fragmentary and that the X-ray emission from stellar winds has a strong contribution from shocks in winds. Chandra high spectral resolution observations of line profiles of O and B stars have shown numerous properties that had not been expected. Here we suggest explanations by considering the X-rays as arising from bow shocks that occur where the stellar wind impacts on spherical clumps in the winds. We use an accurate and stable numerical hydrodynamic code to obtain steady state physical conditions for the temperature and density structure in a bow shock. We use these solutions plus analytic approximations to interpret some major X-ray features: the simple power-law distribution of the observed emission measure derived from many hot star X-ray spectra and the wide range of ionization stages that appear to be present in X-ray sources throughout the winds. Also associated with the adiabatic cooling of the gas around a clump is a significant transverse velocity for the hot plasma flow around the clumps, and this can help to understand anomalies associated with observed line widths, and the differences in widths seen in stars with high and low mass-loss rates. The differences between bow shocks and the planar shocks that are often used for hot stars are discussed. We introduce an ‘‘on the shock’’ approximation that is useful for interpreting the X-rays and the consequences of clumps in hot star winds and elsewhere in astronomy.

Mon travail de thèse présente deux types de structures denses : des sources froides compactes détectées par Planck et des condensations denses dans une région de photodissociation (PDR), à savoir la Barre d’Orion. Les deux types de structures sont étroitement liées à la formation des étoiles. Les sources froides sont étudiées comme objets potentiellement gravitationnellement liés, c’est-à-dire comme objets préstellaires. La Barre d’Orion est intéressante en tant que PDR à fort champ UV (G0 ∼104) prototypique, avec plusieurs disques protoplanétaires connus, éclairés par les jeunes étoiles du Trapèze.D’abord, je présente un article publié dans A&A: The Physical state of selected cold clumps. Dans cet article, nous avons comparé les observations du continuum de la poussière par Herschel provenant de l’open time key program Galactic Cold Cores (Herschel) aux observations de raies moléculaires par le radiotélescope de 20-m de l’Onsala Space Observatory en Suède. Les objets ont été sélectionnés en fonction de leur luminosités et faibles températures de couleur des poussières (T∼10−15 K). Nous avons calculé les masses du viriel et de Bonnor-Ebert et les avons comparées aux masses déduites à partir des observations. Les résultats indiquent que la plupart des objets froids observés ne sont pas nécessairement préstellaires.Dans mon étude de la Barre d’Orion, j’utilise des observations de l’instrumentPACS d’Herschel du programme Unveiling the origin and excitation mechanisms of the warm CO, OH and CH+ . Je présente des cartes de 110” ×110” du cation méthylidyne (CH+ J=3-2), des doublets de OH à 84 μm, et des raies de CO á hauts J (J=19-18). C’est la première fois que ces traceurs des PDR ont présentés avec une telle résolution spatiale et un tel rapport signal-sur-bruit.La répartition spatiale de CH+ et OH montre la même structure de la Barre qui a été vue dans d’autres observations. La morphologie du CH+ et H2 confirme que la formation et l’excitation de CH+ est fortement dépendante du H2 excité vibrationnellement. Le maximum d’émission de OH84 μm correspond à un objet brillant jeune, identifié comme le disque protoplanetaire 244-440.Je présente également des transitions rotationnelles de CO de moyenne (∼20 K) et haute (∼1000 K) énergie. La morphologie de l’émission du CO rotationnellement excité est corrélée avec la présence des petites structures denses irradiées. Nous établissons le lien entre le coeur de ces structures, tracé en CS J=2-1 par Lee et al. (2013) et H 13 CN par Lis and Schilke (2003) et le bord de la PDR, tracé en CO J=19-18 et le H 2 vibrationnellement excitée. Nous montrons également que le CO est principalement excité par le chauffage UV. / In this thesis I present a study of two kinds of dense ISM structures: compact cold sources detected by Planck and dense condensations in a photodissociation region (PDR), namely the Orion Bar detected by ground-based and Herschel telescopes. Both kinds of structures are closely related to star formation. The cold sources are investigated as potentially gravitationally bound, prestellar, objects. The Orion Bar is a highly FUV-illuminated (G0=104) prototypical PDR, with several known protoplanetary disks, illuminated by the young Trapezium stars.First I introduce a paper published in A&A: The Physical state of selected cold clumps. In this paper we compared the Herschel dust continuum observations from the open time key program Galactic Cold Cores to ground based molecular line observations from the 20-m radio telescope of the Onsala Space Observatory in Sweden. The clumps were selected based on their brightness and low dust color temperatures (T=10-15 K). We calculated the virial and Bonnor-Ebert masses and compared them to the masses calculated from the observations. The results indicate that most of the observed cold clumps are not necessarily prestellar.Then I move on to the warm and dense condensations of the ISM. In my study of the Orion Bar, I use observations from PACS instrument on board Herschel from the open time program Unveiling the origin and excitation mechanisms of the warm CO, OH and CH+. I present maps of 110”x110” of the methylidyne cation (CH+ J=3-2), OH doublets at 84 µm, and high-J CO (J=19-18). This is the first time that these PDR tracers are presented in such a high spatial resolution and high signal-to-noise ratio. The CH+ and OH have critical densities (1010 cm-3) and upper level energy temperatures (250 K). In addition the endothermicity of the CH+ + H2 reaction (4300 K) that forms CH+ is comparable to the activation barrier of the O + H2 reaction (4800 K) forming OH. Given these similarities it is interesting to compare their emission. The spatial distribution of CH+ and OH shows the same clumpy structure of the Bar that has been seen in other observations. The morphology of CH+ and H2 confirms that CH+ formation and excitation is strongly dependent on the vibrationally excited H2, while OH is not. The peak in the OH 84 µm emission corresponds to a bright young object, identified as the externally illuminated protoplanetary disk 244-440.Finally, I study the high-J CO in the Orion Bar. I also introduce low- and mid-J CO observations of the area. The high-J CO morphology shows a clumpy structure in the Bar and we establish a link between the dense core of the clumps, traced in CS J=2-1 by Lee et al. (2013) and in H13CN by Lis and Schilke (2003). We also show that the high-J CO is mainly excited by the UV heating.

Submitted by Erika Demachki (erikademachki@gmail.com) on 2014-12-10T14:15:29Z No. of bitstreams: 1 Dissertação - Anna Paula Ferreira Batista Goldfeld Ucker - 2013.pdf: 1541902 bytes, checksum: 9ef28aaf99c986e96d114d3a8e9a83b7 (MD5) / Rejected by Erika Demachki (erikademachki@gmail.com), reason: on 2014-12-10T14:15:39Z (GMT) / Submitted by Erika Demachki (erikademachki@gmail.com) on 2014-12-15T16:26:46Z No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Dissertação - Anna Paula Ferreira Batista Goldfeld Ucker - 2013.pdf: 1541902 bytes, checksum: 9ef28aaf99c986e96d114d3a8e9a83b7 (MD5) / Approved for entry into archive by Erika Demachki (erikademachki@gmail.com) on 2014-12-15T16:34:00Z (GMT) No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Dissertação - Anna Paula Ferreira Batista Goldfeld Ucker - 2013.pdf: 1541902 bytes, checksum: 9ef28aaf99c986e96d114d3a8e9a83b7 (MD5) / Made available in DSpace on 2014-12-15T16:34:02Z (GMT). No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Dissertação - Anna Paula Ferreira Batista Goldfeld Ucker - 2013.pdf: 1541902 bytes, checksum: 9ef28aaf99c986e96d114d3a8e9a83b7 (MD5) Previous issue date: 2013-10-07 / The Citronella Grass currently has excelled in domestic and foreign markets, due to its medicinal properties. The use of the essential oil is increasing, there are several functions, commonly used in the pharmaceutical industry, in agronomic practices (with adoption of conservation methods), used as insecticides, fungicides, in the area of veterinary as ticks and cleaning as disinfectants. The expectation for those who produce the oil is economically viable use your directing for family farmers which can add value to their properties and generate income. It is a little known plant, disclosed and addressed. Given this gap, was aim to work with citronella to evaluate performance in the treatments used, oil yield and seedling production. The challenge of this work is to bring information about the culture, cultivation and their purposes. In the study we evaluated various treatments with organic manure, mineral NPK and control, evaluating oil yield, fresh weight, dry weight, diameter, plant height after cutting. The experimental design was randomized with four replications. In organic treatments which got the biggest highlight was with 0.5 liter of organic fertilizer from fresh cattle manure, which was applied in each pit parcels worked. For the conditions of the State of Goiás plant development ensued in a very adaptable, demonstrating hardiness of the plant, and how it can be profitable for the producer of small income. / O capim citronela tem se destacado atualmente no mercado interno e externo, devido as suas propriedades medicinais. A utilização do seu óleo essencial vem aumentando gradativamente, pois são várias as suas funções, bastante utilizado na indústria farmacológica, nas práticas agronômicas (com adoção de métodos conservacionistas), usados como inseticidas, fungicidas, na área da veterinária como carrapaticida e de limpeza como desinfetantes. A expectativa para quem produz o óleo é viabilizar economicamente o seu uso, direcionando para produtores da agricultura familiar aos quais podem agregar valor em suas propriedades e gerar renda. É uma planta pouco conhecida, divulgada e trabalhada. Diante desta lacuna, objetiva-se trabalhar com citronela para avaliação de rendimento em função dos tratamentos usados, rendimento de óleo e produção de mudas e também buscar informações acerca das suas características agronômicas, multiplicação, desenvolvimento e potencial de produção de óleo essencial. O desafio deste trabalho é trazer informações sobre a cultura, o cultivo e suas finalidades. Na pesquisa foram avaliados três tratamentos orgânicos sendo 0,5 L, 1,0 L e 2,0L aplicado em cada cova das parcelas trabalhadas com esterco bovino, mineral com NPK e testemunha, avaliando-se rendimento de óleo, massa verde, massa seca, diâmetro da touceira, altura de plantas após o corte, antes do corte aguardou-se o desenvolvimento da planta. O delineamento foi casualizado com 4 repetições. Nos tratamentos orgânicos o que obteve o maior destaque foi com 0,5 litro de adubo orgânico a base de esterco bovino. Para as condições da cidade de Goiânia o desenvolvimento da planta se sucedeu de uma forma bem adaptável, demonstrando rusticidade da planta, e o quão pode ser lucrativo para o produtor de pequena renda.

In forensic casework analysis it is necessary to obtain genetic profiles from increasingly smaller amounts of biological material left behind by perpetrators of crime. The ability to obtain profiles from trace biological evidence is demonstrated with so-called ‘touch DNA evidence’ which is perceived to be the result of DNA obtained from shed skin cells transferred from donor to an object or person during physical contact. However, the current method of recovery of trace DNA involves cotton swabs or adhesive tape to sample an area of interest. This "blindswabbing" approach may result in the recovery of biological material from different individuals resulting in admixed DNA profiles which are often difficult to interpret. Profiles recovered from these samples are reported to be from shed skin cells with no biological basis for that determination. A specialized approach for the isolation of single or few cells from ‘touch DNA evidence’ is necessary to improve the analysis and interpretation of recovered profiles. Here we describe the development of optimized and robust micro volume PCR reactions (1-5 μL) to improve the sensitivity and efficiency of ‘touch DNA’ analysis. These methods will permit not only the recovery of the genetic profile of the donor of the biological material, but permit an identification of the tissue source of origin using mRNA profiling. Results showed that the 3.5 uL amplification volume, a fraction of the standard 25 uL amplification volume, was the most ideal volume for the DNA assay, as it had very minimal evaporation with a 50% profile recovery rate at a single cell equivalent input (~5 pg) with reducing amplification volume alone. Findings for RNA showed that by reducing both amplification steps, reverse transcriptase PCR (20 uL) and body fluid multiplex PCR (25 uL), to iv 5 uL, ideal results were obtained with an increase in sensitivity and detection of six different body fluids down to 50 pg. Once optimized at the trace level, the assays were applied to the collection of single and few cells. DNA findings showed that about 40% of a full profile could be recovered from a single buccal cell, with nearly 80% of a full profile recovered from only two cells. RNA findings from collected skin particles of "touched" surfaces showed accurate skin detection down to 25 particles and detection in one clump of particles. The profiles recovered were of high quality and similar results were able to be replicated through subsequent experiments. More studies are currently underway to optimize these developed assays to increase profile recovery at the single cell level. Methods of doing so include comparing different locations on touched surfaces for highest bio-particle recovery and the development of physical characteristics of bio-particles that would provide the most ideal results

For modeling of particulate materials, discrete element method (DEM) is commonly used. It perceives every particle like a single body. A railway ballast loading by trains is a typical example of a particulate discrete material. By a passing train, static and dynamic forces act on a track bed. Cycling loading results in pernament changes in the railway ballast. Cavity creation, agglomeration and ballast cracking lead to damages in rail traffic. Usage of the discrete element method may reveal the real issues of the railway ballast and it may leads to a reduction of costs associated with a design and repairs. This thesis is focused on the ballast modeling and identification of the discrete model parameters. Obtained results are compared with real experiments from Nottingham University.

L’Agence nationale pour la gestion des déchets radioactifs (l’Andra) en France propose un nouveau type de voussoirs de tunnel pour les ouvrages très profonds. Pour éviter des segments de tunnel trop épais, ils proposent d’intégrer une couche de matériau granulaire sur l’extrados d’un voussoir moins épais. Cette approche prétend utiliser la grande compressilibité de la couche granulaire constituée de particules broyables et les transferts de charge interne au matériau granulaire pour réduire l’épaisseur du voussoir tout en gardant des performances mécaniques importantes. Un segment de tunnel avec une telle conception est appelé un VMC monobloc compressible (brevet en instance de l’Andra & CMC). Il s’agit d’un nouveau type de revêtement de tunnel particulièrement innovant.Cette thèse est consacrée à la création d’un modèle numérique capable de reproduire le comportement mécanique d’un couche granulaire très compressible à l’aide de la méthode aux éléments discrets (DEM) en 3D. Le milieu granulaire est constitué de particules d’argile cylindriques creuses appelées textitcoques. Chaque coque est un tube de 2 cm de long avec un diamètre de 2 cm. La faible épaisseur de la coque cylindrique la rend essentiellement constituée de vide entourée d’une fine couche d’argile. Dans le modèle, un cluster sécable (la coque) est généré à l’aide de clumps sphéro-polyédriques allon- gées . Ces clumps, appelés secteurs, sont associés entre eux en utilisant deux lois de contact adhésives. Si la combinaison des forces de contact normales et tangentielles satisfait un critère de charge spécifique, la coque se casse au niveau de l’interface entre les deux secteurs. L’outil DEM Rockable mis au point pour cette recherche peut fonctionner sur ces particules fragiles. Les propriétés mécaniques des coques, composé de 12 à 24 secteurs, sont ajustées à l’aide d’essais de compression radiale uniaxiale (verticale). Les expériences à l’échelle du grain sur les coques en argile cuite ont servi de référence. Nous avons déterminé la plage réelle de rupture et sa distribution statistique (Weibull). Les paramètres numériques et mécanique ainsi obtenus ont été validés avec succès dans le cas de la compression radiale d’une coque contrainte latéralement.Dans un premier temps, l’étude des assemblages de coques porte sur la caractérisation expérimen- tale des échantillons avec un controle sur les variables d’état initiales telles que la densité et l’orienta- tions des coques. La reconstruction 3D à partir de tomographies à rayons X d’échantillons de coques carottés dans l’extrados d’un voussoir nous a permis de caractériser l’anisotropie de l’orientation des particules. Il s’agit là d’une information précieuse pour la génération d’échantillons numériques ayant les caractéristiques initiales pertinentes. Deuxièmement, des simulations DEM de compressions oedo- métriques sur des échantillons de ⟨2 000⟩ coques sont réalisées. Une étude paramétrique permet de mettre en évidence le rôle des variables d’état initiales. Un ensemble bien choisi de variables initiales et des paramètres DEM correctement adaptés permettent d’obtenir des simulations prédictives pertinentes pour une comparaison avec les expériences de laboratoire. Une analyse micro-mécanique de l’effet de la proportion des grains cassés sur les contraintes locales exercées sur les coques (et les fragments) est effectuée. Il est observé que la rupture des coques entraîné une compressibilité élevée du matériau. Par conséquent, la réponse mécanique en déformation est considérée comme une conséquence directe de l’évolution de la rupture des particules. Pour finir, un modèle analytique de prédiction de la re- lation Contrainte↔Déformation est proposé dans le cas de la compression oedométrique. Ce modèle prédictif tient compte des variables internes du milieu granulaire comme la résistance mécanique en compression des coques. / The National Agency for Radioactive Waste Management (FR Andra) in France suggested a new way to design a tunnel lining, especially, beneficial in the case of very deep tunnels. To avoid very thick tunnel segments, they propose to integrate a layer of granular material on the extrados of the thinner lining. This approach takes the advantages of the compressible capacity of the crushable particles and the load transfer in the granular material. A tunnel segment with such design is called a Mono-block Compressible Arch-segment VMC (Andra’s & CMC’s pending patent) and is an innovative new type of tunnel linings.This PhD dissertation is dedicated to the creation of a numerical model capable of reproducing the mechanical behaviour of this compressible granular layer using 3D Discrete Element Method (DEM). The granular packing is made of the brittle hollow coarse-size cylindrical particles, called shells. Each shell is a 2 cm long tube with a diameter of 2 cm. Its small thickness makes the cylindrical shell mainly made of void surrounded by a thin layer of clay. In the model, a breakable cluster (shell) is generated using sphero-polyhedral elongated clumps. These clumps, called sectors, are glued together using two adhesive contact force laws. If the combination of the normal and tangential contact forces exceeds a suitable failure criterion, a de-clustering of the shell (breakage) occurs. The DEM tool Rockable devel- oped for this research can operate on such crushable particles. The mechanical properties of the shell model, composed of 12 to 24 sectors, are adjusted in the case of a uniaxial (vertical) radial compres- sion of shells. The preceding grain-scale experiments on the true shells made of baked clay serve as a reference. We determine the true range of the failure tensile load and its statistical Weibull distribu- tion. The user-specified parameters is then successfully validated in the case of radial compression of a horizontally constrained shell.Firstly, the macroscopic study of shell assemblies focuses on the experimental characterisation of the samples with a control of the initial state variables like a number density and a spatial arrangement of shells (shells orientations). 3D reconstruction from X-ray tomographies of the original coated shells samples extracted from the extrados of a tunnel segment help us to characterise the anisotropy of the shells orientation. This is a piece of valuable information to the generation the numerical samples of shells with relevant initial features. Secondly, a series of DEM oedometric tests on ⟨1 000 : 2 000⟩ shells is simulated. A parametric study successfully leads to the understanding of each internal state variable role. A well-chosen set of initial variables with properly adapted DEM parameters give the relevant predictive simulations for a final comparison with the experimental oedometer tests. Thanks to a discrete insight into the micromechanics, the evolutions of the breakage level, the orientation anisotropy and the local stresses exerted on the shells (and/or the fragments) are quantified during the compression. The breakage of the shells result in high compressibility of the material. Therefore, the mechanical response is seen as a consequence of the breakage evolution. Finally, an analytical model is suggested in order to predict the Stress↔Void ratio relationship knowing the initial state of the sample and the tensile strength of the constituents: the shells.

No description available.