Добірка наукової літератури з теми "Effet Hall de vallée"

Cet article vise à analyser le filmDans la vallée d’Elahà partir d’une perspective théorique féministe de la sécurité internationale, afin de déceler les rapports de genre et de « race » qui sous-tendent la construction de différentes masculinités au sein des discours et des narrations sur la sécurité internationale, la guerre et la militarisation, notamment dans le contexte de la guerre en Irak et des productions culturelles s’y référant. En effet, si le film est critique de plusieurs aspects de la guerre en Irak, il est à se demander si ces critiques ont entraîné une véritable déconstruction des discours genrés et racisés qui légitiment et rendent possibles la militarisation et les guerres, ou si ceux-ci, même critiqués, sont reconduits par la narration du conflit. L’article soutient que la masculinité hégémonique du personnage principal est construite en opposition à une masculinité pervertie par la guerre en Irak chez les jeunes soldats y ayant combattu, limitant la critique à cette guerre spécifique et non à la guerre en général.

Résumé Deux petites tourbières, situées sur chacun des versants de la vallée de la Gui- sane (Alpes françaises internes du Sud), ont fait l'objet d'analyses de pollen et de macro- restes végétaux. Leur étude comparée a permis de préciser le rôle de l'exposition et des activités anthropiques dans la dynamique forestière holocène de la vallée. Le contexte microclimatique lié à l'exposition a déterminé la répartition de la végétation entre 9000 et 4000 étal. BP. En effet, vers 8500 étal. BP, l'ubac était déjà couvert de pinèdes tandis que les boisements de Pinus et de Betula colonisaient à peine les pentes asylvatiques de l'adret. À partir de 6500 étal. BP, les sapinières sont devenues dominantes sur l'ubac, l'adret étant toujours dominé par les pinèdes. L'émergence de la perturbation anthropique vers 4000 étal. BP se traduisit par la régression des sapinières sur l'ubac et l'ouverture du milieu sur l'adret. Cette dernière est associée à une augmentation importante de la richesse pollinique qui, dans cette étude, se révèle être un bon indicateur des phases forestières et asylvatiques de la végétation environnante. Les activités anthropiques, en modifiant radicalement la végétation de la vallée depuis 4000 ans, masquèrent donc l'influence de l'exposition ; le mélézin couvrit l'ubac tandis que pelouses et pinèdes s'étendaient sur l'adret. La reconstitution de l'histoire de la végétation locale met enfin en évidence l'influence primordiale du milieu environnant sur le développement des sites.

Les palissades suscitent la curiosité. Elles symbolisent le défi que les premiers colons durent surmonter, soit celui de créer une enclave de protection au coeur d’un milieu hostile, et ce, avec des moyens plutôt rudimentaires. Des forts, des postes de traite et des missions ont notamment été ceints d’une clôture de pieux. Plusieurs villages ont aussi été dotés de tels ouvrages défensifs, mais dans plusieurs cas, il s’agissait plutôt de petits fortins et de redoutes aménagés en marge des habitations et ne protégeant que quelques bâtiments importants, dont l’église, le moulin et le manoir. Toutefois, trois villages français établis à la fin du xviie siècle, soit La Prairie, Boucherville et Pointe-aux-Trembles se distinguent d’autres établissements ruraux. En effet, ces villages étaient entièrement ceints de clôtures de pieux dans lesquelles les maisons étaient regroupées et organisées autour d’une trame de rues. Ces trois villages ont laissé des témoins archéologiques uniques au Québec, ainsi qu’une empreinte toujours visible dans le paysage.

L’hydrologie du fleuve Sénégal est tributaire de l’influence cumulée de la variabilité climatique et des barrages de Diama et de Manantali depuis la mise en service de ces derniers. Aujourd’hui, dans la vallée du fleuve, on assiste à une recrudescence des inondations. C’est dans ce contexte que nous nous proposons d’étudier l’évolution du régime hydrologique du fleuve Sénégal afin d’appréhender, à la fois, l’effet de la variabilité climatique et des barrages sur les écoulements. Une approche statistique associant plusieurs méthodes complémentaires (indices centrés et réduits, tests de détection de ruptures des moyennes et procédure de segmentation des séries) a été utilisée. Nos analyses nous ont permis de constater, sur le bassin du fleuve Sénégal, la rupture climatique des années 1970 qui s’est traduite par une diminution de l’écoulement moyen annuel mais aussi des cotes maximales annuelles et minimales annuelles. Cependant, une reprise significative des écoulements moyens annuels est observée à partir des environs de l’année 1994, ce qui atteste l’entrée dans une nouvelle période climatique plus humide que celle des décennies 1970 et 1980 à l’échelle du bassin du fleuve Sénégal. En outre, dans la vallée du fleuve, l’écoulement moyen annuel est renforcé, depuis la fin des années 1980 et le début des années 1990, par l’effet cumulé des barrages (par leurs impacts sur l’occupation du sol) et de la variabilité climatique. En effet, les barrages ont entraîné une hausse des crues maximales annuelles à la station de Bakel depuis 1994 et un soutien considérable des étiages dans toute la vallée du fleuve Sénégal.

Un site expérimental représentatif du milieu calcaire fissuré a été étudié dans le Jurassique supérieur de la vallée de la Loue. Un forage carotté de trente mètres a été réalisé et étudié par différentes techniques de laboratoire (porosité, perméabilité, vitesse ultrasonique, quantification de la fissuration) et de terrain (essais hydrauliques par injection entre obturateurs, diagraphies soniques, densité). Le massif rocheux concerné a été exploré en surface à partir de la sismique réfraction. Les principaux résultats obtenus permettent de relier les paramètres hydrauliques à la fissuration du massif calcaire. On constate une mauvaise relation entre les mesures de laboratoire et de terrain par suite d'un effet d'échelle, les investigations étant faites sur des volumes variant de quelques centimètres cubes à plusieurs mètres cubes. En effet, la matrice homogène et isotrope est perturbée par des fissures (fermées ou ouvertes). Le milieu continu représenté par la matrice et observé au laboratoire s'avère discontinu sur le terrain. L'indice le obtenu à partir de la diagraphie sonique paraît intéressant, mais doit être utilisé avec prudence et après correction dans les zones à argilosité reconnue, en effet dans ces zones on constate que pour des valeurs supérieures à 10 de l'indice lc brut, aucun écoulement n'a été mis en évidence par essai hydraulique. Un abaque de correction C (lc) a donc été établi qui tient compte de la teneur en argile et qui permet de proposer un indice corrige le -C (lc) plus fiable.

<p style="text-align: justify;">La méthode des groupes écologico-géographiques de LEVADOUX ou sortotypes de NEGRUL permet un classement ordonné des cépages.</p><p style="text-align: justify;">Pour la France, le travail n 'a pas été achevé et des lacunes persistent toujours. L'une d'entre elles semble pouvoir être comblée avec le groupe des Messiles spécifiquement attaché à la moyenne et basse vallée de la Loire et comprenant principalement les Mesliers, les Chenins et le Sauvignon. Ces cépages présentent, en effet, d'évidentes parentés anatomiques, ampélométriques, génétiques voire technologiques.</p><p style="text-align: justify;">Le travail s'efforce d'appliquer à nouveau une théorie qui parait n'avoir rien perdu de son intérêt.</p>

Le graphène a une structure de bande unique que la bande de conduction et la bande de valence se touchent aux points de Dirac K and K', ce qui en fait un semi-conducteur à écart nul. La structure de la bande peut être modifiée en introduisant un potentiel périodique (super-réseau) qui place le graphène au-dessus du BN pour un alignement cristallographique. Dans cette thèse, je discute principalement des propriétés de transport de charge du graphène et de ses hétérostructures. Différentes méthodes de fabrication d'échantillons sont introduites pour réaliser des hétérostructures en fonction du but de l'expérience. Nous utilisons différentes techniques de transport dans le graphène monocouche/bicouche et leurs hétérostructures d'alignement pour étudier différents mécanismes de diffusion afin de comprendre si ceux-ci sont modifiés par la présence du super-réseau. Nous avons constaté que la diffusion aux petits angles est dominante dans les échantillons de graphène monocouche et bicouche. Grâce aux mesures de focalisation magnéto transversale (TMF), nous concluons que la diffusion électron-électron domine la suppression du TMF. Cependant, nous observons une réponse non identique dans l'alignement 0 ̊ et 60 ̊ pour le graphène bicouche dans TMF. Cela montre la structure de bande différente de deux alignements et nous indique que la symétrie de l'hétérostructure bicouche graphène/BN n'est pas de 60 ̊. Nous observons en outre la même réponse non identique dans l'effet Valley Hall (VHE) selon laquelle l'alignement 60 ̊ ne nous donne pas la relation cubique qui représente le VHE. Ce fait nous indique la triple symétrie du graphène bicouche/BN et montre également que la courbure de Berry n'est pas la seule explication du VHE. Nous proposons ici une explication possible de la relaxation de la structure atomique. La contrainte exercée sur la deuxième couche de graphène est différente et crée des champs de jauge qui agissent comme un pseudo-champ magnétique différent et affectent effectivement le VHE
Graphene has unique band structure that conduction band and valence band touch at the Dirac points K and K', making it a zero gap semiconductor. The band structure can be modified by introducing periodic potential (superlattice) that place graphene on top of BN to crystallographic alignment. In this thesis, I mainly discuss the charge transport properties of graphene and its heterostructures. Different sample fabrication methods are introduced to make stacks depending on experiment purpose. We use different transport techniques in monolayer/bilayer graphene and their alignment heterostructures to study different scattering mechanisms in order to understand if these are modified by the presence of the superlattice. We found that small angle scattering is dominant in both monolayer and bilayer graphene samples. Through the transverse magneto focusing (TMF) measurements, we have the conclusion that electron-electron scattering is in dominance of TMF suppression. However, we observe nonidentical response in 0 ̊ and 60 ̊ alignment for bilayer graphene in TMF. This shows the different band structure of two alignments and tell us that the symmetry of bilayer graphene/BN heterostructure is not 60 ̊.We further observe the same nonidentical response in valley Hall effect (VHE) that 60 ̊ alignment doesn't give us the cubic relation which represents the VHE. This fact tells us the three fold symmetry of bilayer graphene/BN and also show that Berry curvature is not the only explanation of VHE. Here we propose a possible explanation about atomic structure relaxation. The strain on the second layer of graphene is different and create gauge fields that act as different pseudo magnetic field and indeed affect the VHE

Les propulseurs à effet Hall sont utilisés pour le maintien en poste des satellites géostationnaires. La singularité de ce type de moteur est l'utilisation d'un champ magnétique dont le rôle est de piéger des électrons et de permettre la formation d'une région à fort champ électrique. Les ions formés sont accélérés dans ce champ électrique puis extraits du plasma pour fournir la poussée. La compréhension du transport des électrons à travers les lignes de champ magnétique reste un enjeu crucial pour prédire le fonctionnement du moteur. Plusieurs mécanismes de transport comme les phénomènes collisionnels et la turbulence ont été identifiés mais leur contribution exacte n'a pas encore été élucidée. Sur la base de deux modèles numériques particulaires ("Particle-In-Cell"), composés de schémas de discrétisation des trajectoires explicite et implicite, ce travail de thèse se propose d'analyser le déroulement d'une décharge type afin d'isoler les mécanismes de transport électronique mais aussi, de mieux cerner l'influence de la turbulence plasma sur la nature de la décharge. L'accent est mis sur le caractère fortement instationnaire de celle-ci. Nous étudions aussi un mécanisme de transport particulier, gouverné par la turbulence et les collisions volumiques, à l'aide d'un modèle numérique particule-test
Hall effect thrusters are used for station-keeping of satellites in geostationary orbit. The originality of this kind of thruster is the use of a magnetic field which traps the electrons and creates a high electric field region. In this region, the ions are accelerated and extracted from the plasma to provide a thrust. Electron transport across the magnetic field lines is a major issue in predicting the thruster performance. Several transport mechanisms as collision phenomena and plasma turbulence have been identified to play a role but their exact contribution is still not clear. Based on two numerical particle models ("Particle-In-Cell"), composed of an explicit and implicit trajectory-tracking schemes, this work thesis aims at analyzing the proceeding of a discharge in order to isolate the transport mechanisms of electrons. It also aims at providing a better understanding of the plasma turbulence on the discharge behavior. We emphasize the strong unstationnary character of the discharge. We also study a particular transport mechanism, governed by turbulence and volumic collisions, using a particle-test numerical model

Dans le cadre de cette thèse, nous avons étudié une famille de capteurs à effet Hall, composé de croix de Hall submicroniques et de microgradiomètres réalisée à partir d'hétérostructures à puits quantiques optimisées. De par leurs performances, ces capteurs pourraient permettre d'aborder de façon plus efficace, l'étude à l'échelle nanométrique, des propriétés magnétiques de la matière micro- et nanostructurée, ainsi que celles des nanocomposants. La première partie de cette thèse est consacrée à la fabrication et à la caractérisation des capteurs. On étudiera tout d'abords les résistances de contacts et les largeurs de déplétion limitant le fonctionnement des capteurs puis on s'intéressera à la métrologie des composants. Dans la seconde partie, on étudie le passage par effet tunnel des électrons entre les bords de l'échantillon. En régime d'effet Hall Quantique, il apparaît des fluctuations aux extrémités des plateaux à la fois sur les résistances transverses et longitudinales. Les pics sur le côté fort champ de la transition sont différent de ceux situé sur le côté faible champ de la transition. Il diffère aussi par leur comportement en température. Du côté des fort facteurs de remplissage, l'évolution en température des pics permet de les relier à un effet tunnel résonnant à travers un état créé par un des antidots se formant lors du remplissage des niveaux de Landau. Du côté des faibles facteurs de remplissage, la dépendance en température est différente et est reliable à un processus de "Variable Range Hopping". Ces processus peuvent être reliés à l'assymétrie de la densité d'états
As part of this thesis, we studied a family of Hall effect sensors , composed of submicrometers Hall cross and microgradiometers made from optimized quantum wells. The first one left this thesis is dedicated to manufacture and to characterization of sensors. They will study everything of manners the resistance of contacts and the depletion length restricting the functioning of sensors In second part, we study the tunnel effect of electrons between the edges of the sample. In the presence of a quantizing magnetic field, at the transition between two quantized Hall plateaus, a succession of sharp peaks is detected in the Hall signal RH and in the longitudinal resistance RL. The peaks appearing on the high-í side of the RL transition appear to be different from the peaks appearing on the low-í side. They mainly differ by their temperature dependence. On the high-í side of the RL transition, the temperature evolution of the peaks is typical for resonant tunneling through a single state in one of the antidots that are progressively formed when the initially occupied LL is emptied. On the low í of the transition, by contrast, the temperature dependence is different. This may be related to the asymmetry of the density of states

Nous étudions un certain nombre de manifestations de l'effet Hall quantique fractionnaire dans les bicouches d'effet Hall quantique, des puits quantiques larges ou le graphène, dans lesquels les degrés de liberté multicomposantes produisent des phénomènes physiques insolites. Dans la bicouche d'effet Hall quantique du remplissage total nu=1, nous examinons les fonctions d'onde mixtes des bosons composites et fermions composites afin de décrire la destruction de la suprafluidité excitonique au fur et à mesure qu'on augmente la distance entre les deux couches. Nous proposons des fonctions d'onde d'essai qui décriraient bien l'ètat de la bicouche quand il s'agit de distances intermédiaires et nous y ètudions leurs propriétés. Dans la bicouche d'effet Hall quantique du remplissage total nu=1/2 et nu=2/5, nous étudions la transition de phase quantique entre les états multicomposantes de Halperin et les phases polarisées (abeliannes et non-abeliannes) en fonction des modifications effectuées dans le terme tunnel. Afin d'étudier les transitions, nous utilisons à la fois la diagonalisation exacte et la théorie effective BCS. Nous présentons d'autre part un modèle réaliste du puits quantique large que nous utilisons dans l'examen des états avec un dénominateur pair, à nu=1/2 et nu=1/4 dans le plus bas niveau de Landau. Nous proposons enfin quelques états d'effet Hall quantique fractionnaire possibles dans le graphène, celles-ci reposant sur l'image multicomposante qui concerne les degrés de liberté de spin et de vallée.

Un des grands défis de l'exploration spatiale est de développer des engins spatiaux capables de parcourir de grandes distances avec le moins de carburant possible. Les propulseurs électriques, comme par exemple le propulseur à effet Hall, permet cela grâce à des vitesses d'éjection très élevées. J'ai cherché à comprendre pendant ma thèse la physique du fonctionnement de ces moteurs, en utilisant des modèles numériques et des diagnostics adaptés. Mon groupe d'accueil travaille depuis une dizaine d'années sur la modélisation hybride de ces moteurs. Pourtant la description fluide des électrons dans ce type de modèle pose encore un certain nombre de problèmes. Le premier, lié à la résolution des équations fluides en 2D, a été résolu grâce à un nouvel algorithme de résolution. Celui-ci nous permet désormais de modéliser plus facilement des moteurs à champ magnétique complexe. Le deuxième concerne la description du transport électronique, mal connu dans la configuration de ces moteurs. Une étude approfondie des résultats d'un modèle particulaire dans les directions axiale et azimutale m'a permis de montrer clairement l'influence d'une onde azimutale de champ électrique, présente dans le moteur, sur le transport électronique. L'étude de mesures expérimentales par spectroscopie laser m'a aussi permis de développer une nouvelle méthode capable d'extraire de ces mesures le profil du champ électrique et du terme source d'ionisation dans le moteur. La comparaison de ces mesures aux résultats du modèle hybride a mis en évidence les limites de la description du transport électronique utilisée jusque-là. Elle a aussi permis de définir une voie possible vers l'amélioration de notre modèle
One of the greatest challenges in space exploration is to develop spacecrafts capable of covering great distances with little fuel. Electric thrusters, among which is the Hall effect thruster, are capable of this thanks to their high exhaust velocity. During my PhD, I have tried to understand the physics involved in these thrusters, by means of numerical models and accurate diagnostics. My hosting group has been working on hybrid modeling of these thrusters for about ten years. However, the electron fluid description in such models is still a challenge. One of the problems of the fluid model is the difficulty of solving the fluid equations in 2D. This first problem has been overcome by using a new algorithm. This algorithm makes it now easier to study thrusters with complex magnetic fields. The second problem concerns electron transport which is not well understood. A deep study of a fully particle model in the axial and azimuthal directions has shown that an azimuthal electric field wave, present in the thruster, enhances the electron transport. Also, I have developed a new method to extract the electric field and ionization term profiles from laser spectroscopy measurements. The comparison between these results and those obtained with our hybrid model shows the limit of the electron transport description used until now. This comparison has also shown a possible path to follow in order to correctly describe the electron transport in hybrid models for Hall effect thrusters

Ce travail est une contribution a l'etude du magnetisme anormal des alliages ce#1##xla#xru#2si#2, depuis le regime fermions lourds existant dans ceru#2si#2 pur jusqu'aux phenomenes de type effet kondo d'impuretes independantes observes dans les alliages fortement dilues en cerium. Il repose sur un ensemble de mesures de transport electrique realisees sur monocristaux: resistivite t (0,02t300 k), constante de hall r#ht (1,5t300 k), magnetoresistance h et tension de hall v#hh entre 0 et 8 t (1,5t7 k). Ceru#2si#2 presente un effet hall anormal, du aux asymetries de diffusion des electrons de conduction sur les sites magnetiques, qui se caracterise par des valeurs positives elevees de r#h. En appliquant des pressions hydrostatiques jusqu'a 10 kbar, nous avons constate une decroissance du terme en t#2 dans le regime liquide de fermi et un deplacement du maximum de r#ht vers les hautes temperatures. Ce comportement est compare aux effets observes anterieurement sur la resistivite et la susceptibilite dans la meme gamme de pression, et discute dans le cadre des modeles existants. La substitution du lanthane au cerium, en detruisant les effets de coherence a basse temperature, induit une tres forme augmentation de r#ht0. Elle a egalement pour effet d'abaisser la temperature caracteristique des fluctuations de spins et d'augmenter la portee des interactions magnetiques intersites, permettant ainsi le developpement d'une structure antiferromagnetique modulee a partir de x0,08. L'apparition de l'ordre se traduit sur les courbes t par la presence, au voisinage de t#n, d'anomalies dont la nature varie suivant la concentration. Pour 0,2x0,7, on observe en outre un changement de pente aux environs de 2 k qui peut etre relie a une augmentation de l'harmonique 3 de la modulation des moments magnetiques. A l'etat dilue, les ions de cerium se comportent essentiellement co

La dynamique d'ondes d'Alfvén se propageant dans un plasma le long d'un champ magnétique uniforme est étudiée dans le cadre de la magnétohydrodynamique avec effet Hall (MHD-Hall), qui étend la MHD usuelle à des échelles comparables à la longueur inertielle des ions et à des fréquences proches de la résonance cyclotron ionique. La validité de la MHD-Hall, ainsi que les propriétés de ces ondes qui dans ce domaine de fréquences deviennent dispersives, sont discutées en introduction. Les ondes d'Alfvén polarisées circulairement, solutions exactes des équations de la MHD-Hall, sont soumises à diverses instabilités conduisant à de violents effets non-linéaires. Après une première étude dans un cadre unidimensionnel, le problème est considérée pour des configurations tridimensionnelles. L'instabilité transverse et le collapse d'une onde d'Alfvén de faible amplitude avec formation d'intense filaments magnétiques, prédits par l'équation de Schr"odinger non-linéaire pour l'enveloppe de l'onde, sont établis d'abord dans le cas d'une asymptotique de grande longueur d'onde, et ensuite pour les équations primitives de la MHD-Hall. Ce phénomène de ``filamentation'' est néanmoins affecté par la présence d'instabilités quasi-transverses qui limitent l'amplification du champ et favorisent la formation de forts gradients de densité. Pour des ondes d'Alfvén de plus grande amplitude, les filaments magnétiques deviennent hélicoidaux et des ondes magnéto-sonores non-linéaires se développent. L'instabilité transverse de l'onde d'Alfvén génère en outre un écoulement quasi-incompressible à grande échelle longitudinale qui, après moyennisation sur l'échelle de l'onde, est décrit par la ``MHD réduite''. En augmentant la dispersion, cet écoulement quasi-bidimensionnel est remplacé par une turbulence complètement tridimensionnelle
Alfvén waves propagating in plasma along an ambient magnetic field are studied in the framework of the magnetohydrodynamics including the Hall Effect (Hall-MHD), which extends the usual MHD to scales comparable to the ion inertial length and to frequencies close to the ion-cyclotron resonance. The validity of Hall-MHD, along with the properties of these waves which in this frequency domain become dispersive, that are exact solutions of the Hall-MHD equations, are subject to various instabilities, giving rise to strong nonlinear phenomena. After discussing the one-dimensional case, attention is paid to three-dimensional configurations. The transverse instability and the collapse of a small-amplitude Alfvén wave resulting in the formation of intense magnetic filaments, predicted by the Nonlinear Schrödinger model and then shown to also occur within the full Hall-MHD system. This “filamentation” phenomenon is nevertheless modified by the presence of quasi-transverse instabilities that inhibits the field amplification and favor the generation of strong density gradients. When the Alfvén wave generates a quasi-incompressible flow at large longitudinal scales that, after averaging on the scale of the wave, is described by the « reduced-MHD » model. Increasing the dispersion, this quasi-two-dimensional flow is replaced by a fully three-dimensional turbulence

La question de la propulsion spatiale a été un enjeu politique au coeur de la guerre froide et reste un enjeu stratégique de nos jours. La technologie chimique déjà en place sur les moteurs fusées s'avère être limitée par la vitesse d'éjection et la durée de vie des appareils. La propulsion électrique et plus particulièrement le moteur à effet Hall apparait ainsi comme la technologie la plus performante et la plus utilisée pour diriger un satellite dans l'espace. Cependant, la physique à l'intérieur d'un propulseur étant complexe, de par les champs électromagnétiques ou les processus de collisions importants, toutes les particularités de fonctionnement du moteur ne sont pas parfaitement expliquées. Au bout de centaines d'heures d'essais, certains prototypes voient leur paroi s'éroder de façon anormale et des instabilités électromagnétiques se développent au sein de la chambre d'ionisation. La mobilité des électrons mesurée est en contradiction avec les modèles analytiques et soulèvent des problématiques sur la physique du plasma à l'intérieur de ces moteurs. Par conséquent, le code AVIP a été développé afin de proposer un code 3D massivement parallèle et non-structuré à Safran Aircraft Engines modélisant le plasma instationnaire à l'intérieur du propulseur. Des méthodes lagrangiennes et eulériennes sont utilisées et intégrées dans le code et mon travail s'est concentré sur le développement d'un modèle fluide, étant plus rapide et donc mieux adapté à la conception et au design industriel. Le modèle fluide est basé sur un modèle aux moments avec une expression rigoureuse des termes de collisions et une description précise des conditions limites pour les gaines. Ce modèle a été implémenté numériquement dans un formalisme non structuré et optimisé de façon à être performant sur les nouvelles architectures de calcul. La modélisation retenue et les efforts d'optimisation ont permis de réaliser un calcul réel de moteur à effet Hall afin de retrouver les propriétés globales de fonctionnement telles que l'accélération des ions ou encore la localisation de la zone d'ionisation. Un second cas d'application a finalement reproduit avec succès les instabilités azimutales dans le propulseur avec un modèle fluide et a justifié le rôle de ces instabilités dans le transport anormal des électrons et l'érosion des parois
The space propulsion has been a political issue in the midst of the Cold War and remains nowadays a strategic and industrial issue. The chemical propulsion on rocket engines is limited by its ejection velocity and its lifetime. Electric propulsion and more particularly Hall effect thrusters appear then as the most powerful and used technology for space satellite operation. The physic inside a thruster is complex because of the electromagnetic fields and important collision processes. Therefore, all specificities of the engine operation are not perfectly understood. After hundreds of hours of tests, thruster walls are curiously eroded and electromagnetic instabilities are developping within the ionization chamber. The measured electron mobility is in contradiction with the analytical models and raises issues on the plasma behavior inside the discharg chamber. As a result, the AVIP code was developed to provide a massively parallel and unstructured 3D code to Safran Aircraft Engines modeling unsteady plasma inside the thruster. Lagrangian and Eulerian methods are used and integrated in the solver and my work has focused on the development of a fluid model which is faster and therefore better suited to industrial conception. The model is based on a set of equations for neutrals, ions and electrons without drift-diffusion hypothesis, combined with a Poisson equation to describe the electric potential. A rigorous expression of collision terms and a precise description of the boundary conditions for sheaths have been established. This model has been implemented numerically in an unstructured formalism and optimized to obtain good performances on new computing architectures. The model and the numerical implementation allow us to perform a real Hall effect thruster simulation. Overall operating properties such as the acceleration of the ions or the location of the ionization zone are captured. Finally, a second application has successfully reproduced azimuthal instabilities in the Hall thruster with the fluid model and justified the role of these instabilities in the anomalous electron transport and in theerosion of the walls

Abstract A cognitive bias where a perception of a particular characteristic or quality has an aural influence on perceptions and judgment beyond the characteristic or quality as a result of some association. Based on pioneering research by Thorndike (1920), the halo effect characterizes the situation where positive trait perceptions influence judgments of related traits, while the ‘horns and halo effect’ term characterizes any such influence. The effect is a form of cognitive bias which may present itself in perceptions of judgments of individuals, organizations, products, brands, service experiences, and the like. An example is where individuals perceiving a brand to be strong in an aspect such as name recognition or aesthetics in product design have subsequent positive perceptions of lesser-known qualities such as product durability and reliability. Whereas halo effect refers to positive aural influences, negative influences are sometimes referred to by the ‘horns effect’ term. Marketers must seek to be aware of halo effects in the consumer’s perceptions of a marketer’s offerings and should strive to leverage such effects. In the case of a brand, certain halo effects may be used strategically, as in the case where a well-received new product under the company’s brand name enhances the perceived value of all of the company’s same branded products and enables the firm to introduce more easily another new product under the same brand as well.

Abstract Within the past decade there has been a resurgence of interest in the dynamics of superfluid and superconducting vortices. One source of motivation for this topic may be attributed to the discovery of the quantum Hall effect (von Klitzing et al., 1980), which led to the suggestion that elementary excitations in 2D systems may obey nonstandard statistics (Wilczek, 1982; Halperin, 1984). Haldane and Wu (1985) pointed out a powerful analogy between the dynamics of a vortex in a 2D superfluid film and the electron motion in a cyclotron orbit. critical value.

Since the liberalization of the airline industry, the low-cost business model has been developed worldwide and a new business model of long-haul low-cost carriers (LHLCCs) has evolved. This chapter aims to investigate the LHLCC business model from a customer-oriented perspective in terms of service quality and perceived value. For this purpose, the authors investigated the effect of service quality on perceived value for money for LHLCCs. In this chapter, user-generated content was adopted to collect data, and 824 user-generated airline reviews were collected from TripAdvisor.com, the largest tourism-related repository. In order to investigate the relationship, a predictive correlational design was structured and a logistic regression analysis was applied. To contribute to the regression analysis, a receiver operating characteristic (ROC) analysis was performed to measure the classification success. As a result, the logit model describes well the relationship between variables for LHLCCs.

Abstract In the early 1970s, most industrialized countries were adversely affected by a sharp rise in oil prices. This “oil shock” had a dramatic effect on the value of U.S. firms. As illustrated in Figure 1, the real value of shares listed on the New York Stock Exchange fell by almost half compared to their value at the peak in 1972. This collapse in share prices had a severe negative impact on the wealth of any investor whose portfolio contained a significant amount of stocks. Any investor who was forced to liquidate stocks after market prices fell would have suffered from lower consumption over the remainder of his or her life. Retirees in particular might have been affected in this way.

Quantitative echocardiography refers to using spectral Doppler measurements of blood velocity, in combination with 2D imaging, to obtain calculated values for flow (e.g. stroke volume, regurgitant volume), area (stenotic valve area, regurgitant orifice area), and pressure (e.g. pulmonary artery pressure, transvalvular gradient). Relevant formulae used by the echocardiography machine software for calculating these parameters are provided. Physical phenomena, such jets, the Venturi effect, and the Coanda effect, are explained, along with applications of the continuity principle, the Bernoulli equation, and pressure half-time measurements. The emphasis throughout the chapter is on practical calculations that can be performed rapidly with TOE in the operating room. The concept of pressure recovery is touched on but discussed in more detail in Chapter 13: Prosthetic valves.

This chapter finds that the rate of war-related PTSD declined by about half in the years between the NVVRS and the Longitudinal Study. This furthered the previously reported decline of PTSD by almost half from its initial onset before the NVVRS was conducted. The chapter reports that most Vietnam veterans found value in their war experience, but they also put the war behind them after homecoming, suggesting successful transitions to civilian life. However, while readjustment to life after leaving Vietnam was satisfying and productive for most veterans, a minority believed that their wartime experiences still had a major negative effect on their current lives. Moreover, at the time of the Longitudinal Study, a small group of veterans (4%) suffered from current PTSD, and over three-quarters who had experienced PTSD onsets continued to experience one or more PTSD symptoms.

The world faces many environmental crises such as increased threat of climate change, the depletion of key natural resources, increasing air and water pollution, and growing levels of solid wastes. These issues are becoming the major aspects of value in real estate and a key driver in the decision-making processes. The strategic sustainability process called “the halo effect” was more worldwide which is affected by the popularity in environmental actions criteria. It showed consequence that green concept has to not only focus on technical or moral issues, but also need to base more on the economic and financial imperative.

Transition metal dichalcogenides (TMDs) have attracted vast interest as layered semiconductors with high electrical and optical properties. Among them, monolayer MoS2 is a direct gap semiconductor with its gap energy in the visible range (Fig. 1(a)). Interestingly, excitonic states in monolayer MoS2 are stabilized owing to the intrinsic two-dimensional nature, and the binding energy reaches several hundred meV.

High Grain Protein Content (GPC) of wheat is important for improved nutritional value and industrial quality. However, selection for this trait is limited by our poor understanding of the genes involved in the accumulation of protein in the grain. A gene with a large effect on GPC was detected on the short arm of chromosome 6B in a Triticum turgidum ssp. dicoccoides accession from Israel (DIC, hereafter). During the previous BARD project we constructed a half-million clones Bacterial Artificial Chromosome (BAC) library of tetraploid wheat including the high GPC allele from DIC and mapped the GPC-B1 locus within a 0.3-cM interval. Our long-term goal is to provide a better understanding of the genes controlling grain protein content in wheat. The specific objectives of the current project were to: (1) complete the positional cloning of the GPC-B1 candidate gene; (2) characterize the allelic variation and (3) expression profile of the candidate gene; and (4) validate this gene by using a transgenic RNAi approach to reduce the GPC transcript levels. To achieve these goals we constructed a 245-kb physical map of the GPC-B1 region. Tetraploid and hexaploid wheat lines carrying this 245-kb DIC segment showed delayed senescence and increased GPC and grain micronutrients. The complete sequencing of this region revealed five genes. A high-resolution genetic map, based on approximately 9,000 gametes and new molecular markers enabled us to delimit the GPC-B1 locus to a 7.4-kb region. Complete linkage of the 7.4-kb region with earlier senescence and increase in GPC, Zn, and Fe concentrations in the grain suggested that GPC-B1 is a single gene with multiple pleiotropic effects. The annotation of this 7.4-kb region identified a single gene, encoding a NAC transcription factor, designated as NAM-B1. Allelic variation studies demonstrated that the ancestral wild wheat allele encodes a functional NAC transcription factor whereas modern wheat varieties carry a non-functional NAM-B1 allele. Quantitative PCR showed that transcript levels for the multiple NAMhomologues were low in flag leaves prior to anthesis, after which their levels increased significantly towards grain maturity. Reduction in RNA levels of the multiple NAMhomologues by RNA interference delayed senescence by over three weeks and reduced wheat grain protein, Zn, and Fe content by over 30%. In the transgenic RNAi plants, residual N, Zn and Fe in the dry leaves was significantly higher than in the control plants, confirming a more efficient nutrient remobilization in the presence of higher levels of GPC. The multiple pleiotropic effects of NAM genes suggest a central role for these genes as transcriptional regulators of multiple processes during leaf senescence, including nutrient remobilization to the developing grain. The cloning of GPC-B1 provides a direct link between the regulation of senescence and nutrient remobilization and an entry point to characterize the genes regulating these two processes. This may contribute to their more efficient manipulation in crops and translate into food with enhanced nutritional value. The characterization of the GPC-B1 gene will have a significant impact on wheat production in many regions of the world and will open the door for the identification of additional genes involved in the accumulation of protein in the grain.

High Grain Protein Content (GPC) is a desirable trait in breadmaking and pasta wheat varieties because of its positive effects on quality and nutritional value. However, selection for GPC is limited by our poor understanding of the genes involved in the accumulation of protein in the grain. The long-term goal of this project is to provide a better understanding of the genes controlling GPC in wheat. The specific objectives of this project were: a) to develop a high-density genetic map of the GPC gene in tetraploid wheat, b) to construct a T. turgidum Bacterial Artificial Chromosome (BAC) library, c) to construct a physical map of the GPC gene and identify a candidate for the GPC gene. A gene with a large effect on GPC was detected in Triticum turgidum var. dicoccoides and was previously mapped in the short arm of chromosome 6B. To define better the position of the Gpc-B1 locus we developed homozygous recombinant lines with recombination events within the QTL region. Except for the 30-cM region of the QTL these RSLs were isogenic for the rest of the genome minimizing the genetic variability. To minimize the environmental variability the RSLs were characterized using 10 replications in field experiments organized in a Randomized Complete Block Design, which were repeated three times. Using this strategy, we were able to map this QTL as a single Mendelian locus (Gpc-B1) on a 2.6-cM region flanked by RFLP markers Xcdo365 and Xucw67. All three experiments showed that the lines carrying the DIC allele had an average absolute increase in GPC of 14 g/kg. Using the RFLP flanking markers, we established the microcolinearity between a 2.l-cM region including the Gpc-B1 gene in wheat chromosome 6BS and a 350-kb region on rice chromosome 2. Rice genes from this region were used to screen the Triticeae EST collection, and these ESTs were used to saturate the Gpc-B1 region with molecular markers. With these new markers we were able to map the Gpc-B1 locus within a 0.3-cM region flanked by PCR markers Xucw83 and Xucw71. These flanking markers defined a 36-kb colinear region with rice, including one gene that is a potential candidate for the Gpc-B1 gene. To develop a physical map of the Gpc-B1 region in wheat we first constructed a BAC library of tetraploid wheat, from RSL#65 including the high Gpc-B1 allele. We generated half- million clones with an average size of l3l-kb (5.1 X genome equivalents for each of the two genomes). This coverage provides a 99.4% probability of recovering any gene from durum wheat. We used the Gpc-BI flanking markers to screen this BAC library and then completed the physical map by chromosome walking. The physical map included two overlapping BACs covering a region of approximately 250-kb, including two flanking markers and the Gpc-B1 gene. Efforts are underway to sequence these two BACs to determine if additional wheat genes are present in this region. Weare also developing new RSLs to further dissect this region. We developed PCR markers for flanking loci Xucw79andXucw71 to facilitate the introgression of this gene in commercial varieties by marker assisted selection (httQ://maswheat.ucdavis.edu/ orotocols/HGPC/index.hlm). Using these markers we introgressed the Gpc-B1 gene in numerous pasta and common wheat breeding lines.

Banco de la República is celebrating its 100th anniversary in 2023. This is a very significant anniversary and one that provides an opportunity to highlight the contribution the Bank has made to the country’s development. Its track record as guarantor of monetary stability has established it as the one independent state institution that generates the greatest confidence among Colombians due to its transparency, management capabilities, and effective compliance with the central banking and cultural responsibilities entrusted to it by the Constitution and the Law. On a date as important as this, the Board of Directors of Banco de la República (BDBR) pays tribute to the generations of governors and officers whose commitment and dedication have contributed to the growth of this institution.1 Banco de la República’s mandate was confirmed in the National Constitutional Assembly of 1991 where the citizens had the opportunity to elect the seventy people who would have the task of drafting a new constitution. The leaders of the three political movements with the most votes were elected as chairs to the Assembly, and this tripartite presidency reflected the plurality and the need for consensus among the different political groups to move the reform forward. Among the issues considered, the National Constitutional Assembly gave special importance to monetary stability. That is why they decided to include central banking and to provide Banco de la República with the necessary autonomy to use the instruments for which they are responsible without interference from other authorities. The constituent members understood that ensuring price stability is a state duty and that the entity responsible for this task must be enshrined in the Constitution and have the technical capability and institutional autonomy necessary to adopt the decisions they deem appropriate to achieve this fundamental objective in coordination with the general economic policy. In particular, Article 373 established that “the State, through Banco de la República, shall ensure the maintenance of the purchasing power of the currency,” a provision that coincided with the central banking system adopted by countries that have been successful in controlling inflation. In 1999, in Ruling 481, the Constitutional Court stated that “the duty to maintain the purchasing power of the currency applies to not only the monetary, credit, and exchange authority, i.e., the Board of Banco de la República, but also those who have responsibilities in the formulation and implementation of the general economic policy of the country” and that “the basic constitutional purpose of Banco de la República is the protection of a sound currency. However, this authority must take the other economic objectives of state intervention such as full employment into consideration in their decisions since these functions must be coordinated with the general economic policy.” The reforms to Banco de la República agreed upon in the Constitutional Assembly of 1991 and in Act 31/1992 can be summarized in the following aspects: i) the Bank was assigned a specific mandate: to maintain the purchasing power of the currency in coordination with the general economic policy; ii) the BDBR was designatedas the monetary, foreign exchange, and credit authority; iii) the Bank and its Board of Directors were granted a significant degree of independence from the government; iv) the Bank was prohibited from granting credit to the private sector except in the case of the financial sector; v) established that in order to grant credit to the government, the unanimous vote of its Board of Directors was required except in the case of open market transactions; vi) determined that the legislature may, in no case, order credit quotas in favor of the State or individuals; vii) Congress was appointed, on behalf of society, as the main addressee of the Bank’s reporting exercise; and viii) the responsibility for inspection, surveillance, and control over Banco de la República was delegated to the President of the Republic. The members of the National Constitutional Assembly clearly understood that the benefits of low and stable inflation extend to the whole of society and contribute mto the smooth functioning of the economic system. Among the most important of these is that low inflation promotes the efficient use of productive resources by allowing relative prices to better guide the allocation of resources since this promotes economic growth and increases the welfare of the population. Likewise, low inflation reduces uncertainty about the expected return on investment and future asset prices. This increases the confidence of economic agents, facilitates long-term financing, and stimulates investment. Since the low-income population is unable to protect itself from inflation by diversifying its assets, and a high proportion of its income is concentrated in the purchase of food and other basic goods that are generally the most affected by inflationary shocks, low inflation avoids arbitrary redistribution of income and wealth.2 Moreover, low inflation facilitates wage negotiations, creates a good labor climate, and reduces the volatility of employment levels. Finally, low inflation helps to make the tax system more transparent and equitable by avoiding the distortions that inflation introduces into the value of assets and income that make up the tax base. From the monetary authority’s point of view, one of the most relevant benefits of low inflation is the credibility that economic agents acquire in inflation targeting, which turns it into an effective nominal anchor on price levels. Upon receiving its mandate, and using its autonomy, Banco de la República began to announce specific annual inflation targets as of 1992. Although the proposed inflation targets were not met precisely during this first stage, a downward trend in inflation was achieved that took it from 32.4% in 1990 to 16.7% in 1998. At that time, the exchange rate was kept within a band. This limited the effectiveness of monetary policy, which simultaneously sought to meet an inflation target and an exchange rate target. The Asian crisis spread to emerging economies and significantly affected the Colombian economy. The exchange rate came under strong pressure to depreciate as access to foreign financing was cut off under conditions of a high foreign imbalance. This, together with the lack of exchange rate flexibility, prevented a countercyclical monetary policy and led to a 4.2% contraction in GDP that year. In this context of economic slowdown, annual inflation fell to 9.2% at the end of 1999, thus falling below the 15% target set for that year. This episode fully revealed how costly it could be, in terms of economic activity, to have inflation and exchange rate targets simultaneously. Towards the end of 1999, Banco de la República announced the adoption of a new monetary policy regime called the Inflation Targeting Plan. This regime, known internationally as ‘Inflation Targeting,’ has been gaining increasing acceptance in developed countries, having been adopted in 1991 by New Zealand, Canada, and England, among others, and has achieved significant advances in the management of inflation without incurring costs in terms of economic activity. In Latin America, Brazil and Chile also adopted it in 1999. In the case of Colombia, the last remaining requirement to be fulfilled in order to adopt said policy was exchange rate flexibility. This was realized around September 1999, when the BDBR decided to abandon the exchange-rate bands to allow the exchange rate to be freely determined in the market.Consistent with the constitutional mandate, the fundamental objective of this new policy approach was “the achievement of an inflation target that contributes to maintaining output growth around its potential.”3 This potential capacity was understood as the GDP growth that the economy can obtain if it fully utilizes its productive resources. To meet this objective, monetary policy must of necessity play a countercyclical role in the economy. This is because when economic activity is below its potential and there are idle resources, the monetary authority can reduce the interest rate in the absence of inflationary pressure to stimulate the economy and, when output exceeds its potential capacity, raise it. This policy principle, which is immersed in the models for guiding the monetary policy stance, makes the following two objectives fully compatible in the medium term: meeting the inflation target and achieving a level of economic activity that is consistent with its productive capacity. To achieve this purpose, the inflation targeting system uses the money market interest rate (at which the central bank supplies primary liquidity to commercial banks) as the primary policy instrument. This replaced the quantity of money as an intermediate monetary policy target that Banco de la República, like several other central banks, had used for a long time. In the case of Colombia, the objective of the new monetary policy approach implied, in practical terms, that the recovery of the economy after the 1999 contraction should be achieved while complying with the decreasing inflation targets established by the BDBR. The accomplishment of this purpose was remarkable. In the first half of the first decade of the 2000s, economic activity recovered significantly and reached a growth rate of 6.8% in 2006. Meanwhile, inflation gradually declined in line with inflation targets. That was how the inflation rate went from 9.2% in 1999 to 4.5% in 2006, thus meeting the inflation target established for that year while GDP reached its potential level. After this balance was achieved in 2006, inflation rebounded to 5.7% in 2007, above the 4.0% target for that year due to the fact that the 7.5% GDP growth exceeded the potential capacity of the economy.4 After proving the effectiveness of the inflation targeting system in its first years of operation, this policy regime continued to consolidate as the BDBR and the technical staff gained experience in its management and state-of-the-art economic models were incorporated to diagnose the present and future state of the economy and to assess the persistence of inflation deviations and expectations with respect to the inflation target. Beginning in 2010, the BDBR established the long-term 3.0% annual inflation target, which remains in effect today. Lower inflation has contributed to making the macroeconomic environment more stable, and this has favored sustained economic growth, financial stability, capital market development, and the functioning of payment systems. As a result, reductions in the inflationary risk premia and lower TES and credit interest rates were achieved. At the same time, the duration of public domestic debt increased significantly going from 2.27 years in December 2002 to 5.86 years in December 2022, and financial deepening, measured as the level of the portfolio as a percentage of GDP, went from around 20% in the mid-1990s to values above 45% in recent years in a healthy context for credit institutions.Having been granted autonomy by the Constitution to fulfill the mandate of preserving the purchasing power of the currency, the tangible achievements made by Banco de la República in managing inflation together with the significant benefits derived from the process of bringing inflation to its long-term target, make the BDBR’s current challenge to return inflation to the 3.0% target even more demanding and pressing. As is well known, starting in 2021, and especially in 2022, inflation in Colombia once again became a serious economic problem with high welfare costs. The inflationary phenomenon has not been exclusive to Colombia and many other developed and emerging countries have seen their inflation rates move away from the targets proposed by their central banks.5 The reasons for this phenomenon have been analyzed in recent Reports to Congress, and this new edition delves deeper into the subject with updated information. The solid institutional and technical base that supports the inflation targeting approach under which the monetary policy strategy operates gives the BDBR the necessary elements to face this difficult challenge with confidence. In this regard, the BDBR reiterated its commitment to the 3.0% inflation target in its November 25 communiqué and expects it to be reached by the end of 2024.6 Monetary policy will continue to focus on meeting this objective while ensuring the sustainability of economic activity, as mandated by the Constitution. Analyst surveys done in March showed a significant increase (from 32.3% in January to 48.5% in March) in the percentage of responses placing inflation expectations two years or more ahead in a range between 3.0% and 4.0%. This is a clear indication of the recovery of credibility in the medium-term inflation target and is consistent with the BDBR’s announcement made in November 2022. The moderation of the upward trend in inflation seen in January, and especially in February, will help to reinforce this revision of inflation expectations and will help to meet the proposed targets. After reaching 5.6% at the end of 2021, inflation maintained an upward trend throughout 2022 due to inflationary pressures from both external sources, associated with the aftermath of the pandemic and the consequences of the war in Ukraine, and domestic sources, resulting from: strengthening of local demand; price indexation processes stimulated by the increase in inflation expectations; the impact on food production caused by the mid-2021 strike; and the pass-through of depreciation to prices. The 10% increase in the minimum wage in 2021 and the 16% increase in 2022, both of which exceeded the actual inflation and the increase in productivity, accentuated the indexation processes by establishing a high nominal adjustment benchmark. Thus, total inflation went to 13.1% by the end of 2022. The annual change in food prices, which went from 17.2% to 27.8% between those two years, was the most influential factor in the surge in the Consumer Price Index (CPI). Another segment that contributed significantly to price increases was regulated products, which saw the annual change go from 7.1% in December 2021 to 11.8% by the end of 2022. The measure of core inflation excluding food and regulated items, in turn, went from 2.5% to 9.5% between the end of 2021 and the end of 2022. The substantial increase in core inflation shows that inflationary pressure has spread to most of the items in the household basket, which is characteristic of inflationary processes with generalized price indexation as is the case in Colombia. Monetary policy began to react early to this inflationary pressure. Thus, starting with its September 2021 session, the BDBR began a progressive change in the monetary policy stance moving away from the historical low of a 1.75% policy rate that had intended to stimulate the recovery of the economy. This adjustment process continued without interruption throughout 2022 and into the beginning of 2023 when the monetary policy rate reached 12.75% last January, thus accumulating an increase of 11 percentage points (pp). The public and the markets have been surprised that inflation continued to rise despite significant interest rate increases. However, as the BDBR has explained in its various communiqués, monetary policy works with a lag. Just as in 2022 economic activity recovered to a level above the pre-pandemic level, driven, along with other factors, by the monetary stimulus granted during the pandemic period and subsequent months, so too the effects of the current restrictive monetary policy will gradually take effect. This will allow us to expect the inflation rate to converge to 3.0% by the end of 2024 as is the BDBR’s purpose.Inflation results for January and February of this year showed declining marginal increases (13 bp and 3 bp respectively) compared to the change seen in December (59 bp). This suggests that a turning point in the inflation trend is approaching. In other Latin American countries such as Chile, Brazil, Perú, and Mexico, inflation has peaked and has begun to decline slowly, albeit with some ups and downs. It is to be expected that a similar process will take place in Colombia in the coming months. The expected decline in inflation in 2023 will be due, along with other factors, to lower cost pressure from abroad as a result of the gradual normalization of supply chains, the overcoming of supply shocks caused by the weather, and road blockades in previous years. This will be reflected in lower adjustments in food prices, as has already been seen in the first two months of the year and, of course, the lagged effect of monetary policy. The process of inflation convergence to the target will be gradual and will extend beyond 2023. This process will be facilitated if devaluation pressure is reversed. To this end, it is essential to continue consolidating fiscal sustainability and avoid messages on different public policy fronts that generate uncertainty and distrust. 1 This Report to Congress includes Box 1, which summarizes the trajectory of Banco de la República over the past 100 years. In addition, under the Bank’s auspices, several books that delve into various aspects of the history of this institution have been published in recent years. See, for example: Historia del Banco de la República 1923-2015; Tres banqueros centrales; Junta Directiva del Banco de la República: grandes episodios en 30 años de historia; Banco de la República: 90 años de la banca central en Colombia. 2 This is why lower inflation has been reflected in a reduction of income inequality as measured by the Gini coefficient that went from 58.7 in 1998 to 51.3 in the year prior to the pandemic. 3 See Gómez Javier, Uribe José Darío, Vargas Hernando (2002). “The Implementation of Inflation Targeting in Colombia”. Borradores de Economía, No. 202, March, available at: https://repositorio.banrep.gov.co/handle/20.500.12134/5220 4 See López-Enciso Enrique A.; Vargas-Herrera Hernando and Rodríguez-Niño Norberto (2016). “The inflation targeting strategy in Colombia. An historical view.” Borradores de Economía, No. 952. https://repositorio.banrep.gov.co/handle/20.500.12134/6263 5 According to the IMF, the percentage change in consumer prices between 2021 and 2022 went from 3.1% to 7.3% for advanced economies, and from 5.9% to 9.9% for emerging market and developing economies. 6 https://www.banrep.gov.co/es/noticias/junta-directiva-banco-republica-reitera-meta-inflacion-3

From this edition, the Financial Stability Report will have fewer pages with some changes in its structure. The purpose of this change is to present the most relevant facts of the financial system and their implications on the financial stability. This allows displaying the analysis more concisely and clearly, as it will focus on describing the evolution of the variables that have the greatest impact on the performance of the financial system, for estimating then the effect of a possible materialization of these risks on the financial health of the institutions. The changing dynamics of the risks faced by the financial system implies that the content of the Report adopts this new structure; therefore, some analyses and series that were regularly included will not necessarily be in each issue. However, the statistical annex that accompanies the publication of the Report will continue to present the series that were traditionally included, regardless of whether or not they are part of the content of the Report. In this way we expect to contribute in a more comprehensive way to the study and analysis of the stability of the Colombian financial system. Executive Summary During the first half of 2015, the main advanced economies showed a slow recovery on their growth, while emerging economies continued with their slowdown trend. Domestic demand in the United States allowed for stabilization on its average growth for the first half of the year, while other developed economies such as the United Kingdom, the euro zone, and Japan showed a more gradual recovery. On the other hand, the Chinese economy exhibited the lowest growth rate in five years, which has resulted in lower global dynamism. This has led to a fall in prices of the main export goods of some Latin American economies, especially oil, whose price has also responded to a larger global supply. The decrease in the terms of trade of the Latin American economies has had an impact on national income, domestic demand, and growth. This scenario has been reflected in increases in sovereign risk spreads, devaluations of stock indices, and depreciation of the exchange rates of most countries in the region. For Colombia, the fall in oil prices has also led to a decline in the terms of trade, resulting in pressure on the dynamics of national income. Additionally, the lower demand for exports helped to widen the current account deficit. This affected the prospects and economic growth of the country during the first half of 2015. This economic context could have an impact on the payment capacity of debtors and on the valuation of investments, affecting the soundness of the financial system. However, the results of the analysis featured in this edition of the Report show that, facing an adverse scenario, the vulnerability of the financial system in terms of solvency and liquidity is low. The analysis of the current situation of credit institutions (CI) shows that growth of the gross loan portfolio remained relatively stable, as well as the loan portfolio quality indicators, except for microcredit, which showed a decrease in these indicators. Regarding liabilities, traditional sources of funding have lost market share versus non-traditional ones (bonds, money market operations and in the interbank market), but still represent more than 70%. Moreover, the solvency indicator remained relatively stable. As for non-banking financial institutions (NBFI), the slowdown observed during the first six months of 2015 in the real annual growth of the assets total, both in the proprietary and third party position, stands out. The analysis of the main debtors of the financial system shows that indebtedness of the private corporate sector has increased in the last year, mostly driven by an increase in the debt balance with domestic and foreign financial institutions. However, the increase in this latter source of funding has been influenced by the depreciation of the Colombian peso vis-à-vis the US dollar since mid-2014. The financial indicators reflected a favorable behavior with respect to the historical average, except for the profitability indicators; although they were below the average, they have shown improvement in the last year. By economic sector, it is noted that the firms focused on farming, mining and transportation activities recorded the highest levels of risk perception by credit institutions, and the largest increases in default levels with respect to those observed in December 2014. Meanwhile, households have shown an increase in the financial burden, mainly due to growth in the consumer loan portfolio, in which the modalities of credit card, payroll deductible loan, revolving and vehicle loan are those that have reported greater increases in risk indicators. On the side of investments that could be affected by the devaluation in the portfolio of credit institutions and non-banking financial institutions (NBFI), the largest share of public debt securities, variable-yield securities and domestic private debt securities is highlighted. The value of these portfolios fell between February and August 2015, driven by the devaluation in the market of these investments throughout the year. Furthermore, the analysis of the liquidity risk indicator (LRI) shows that all intermediaries showed adequate levels and exhibit a stable behavior. Likewise, the fragility analysis of the financial system associated with the increase in the use of non-traditional funding sources does not evidence a greater exposure to liquidity risk. Stress tests assess the impact of the possible joint materialization of credit and market risks, and reveal that neither the aggregate solvency indicator, nor the liquidity risk indicator (LRI) of the system would be below the established legal limits. The entities that result more individually affected have a low share in the total assets of the credit institutions; therefore, a risk to the financial system as a whole is not observed. José Darío Uribe Governor

Macroeconomic summary The Colombian economy sustained numerous shocks in the second quarter, pri¬marily related to costs and supply. The majority of these shocks were unantic¬ipated or proved more persistent than expected, interrupting the recovery in economic activity observed at the beginning of the year and pushing overall inflation above the target. Core inflation (excluding food and regulated items) increased but remained low, in line with the technical staff’s expectations. A third wave of the pandemic, which became more severe and prolonged than the previous outbreak, began in early April. This had both a high cost in terms of human life and a negative impact on Colombia's economic recovery. Between May and mid-June roadblocks and other disruptions to public order had a sig¬nificant negative effect on economic activity and inflation. The combination and magnitude of these two shocks likely led to a decline in gross domestic product (GDP) compared to the first quarter. Roadblocks also led to a significant in¬crease in food prices. The accumulated effects of global disruptions to certain value chains and increased international freight transportation prices, which since the end of 2020 have restricted supply and increased costs, also affected Colombia’s economy. The factors described above, which primarily affected the consumer price index (CPI) for goods and foods, explain to a significant degree the technical staff’s forecast errors and the increase in overall inflation above the 3% target. By contrast, increases in core inflation and in prices for regulated items were in line with the technical staff’s expectations, and can be explained largely by the elimination of various price relief measures put in place last year. An increase in perceived sovereign risk and the upward pressures that this im¬plies on international financing costs and the exchange rate were further con¬siderations. Despite significant negative shocks, economic growth in the first half of the year (9.1%) is now expected to be significantly higher than projected in the April re¬port (7.1%), a sign of a more dynamic economy that could recover more quickly than previously forecast. Diverse economic activity figures have indicated high¬er-than-expected growth since the end of 2020. This suggests that the negative effects on output from recurring waves of COVID-19 have grown weaker and less long-lasting with subsequent outbreaks. Nevertheless, the third wave of the coro¬navirus, and to an even greater degree the previously mentioned roadblocks and disruptions to public order, likely led to a decline in GDP in the second quar¬ter compared to the first. Despite this, data from the monthly economic tracking indicator (ISE) for April and May surpassed expectations, and new sector-level measures of economic activity suggest that the negative impact of the pandemic on output continues to moderate, amid reduced restrictions on mobility and im¬provements in the pace of vaccination programs. Freight transportation registers (June) and unregulated energy demand (July), among other indicators, suggest a significant recovery following the roadblocks in May. Given the above, annual GDP growth in the second quarter is expected to have been around 17.3% (previously 15.8%), explained in large part by a low basis of comparison. The technical staff revised its growth projection for 2021 upward from 6% to 7.5%. This forecast, which comes with an unusually high degree of uncertain¬ty, assumes no additional disruptions to public order and that any new waves of COVID-19 will not have significant additional negative effects on economic activity. Recovery in international demand, price levels for some of Colombia’s export com¬modities, and remittances from workers abroad have all performed better than projected in the previous report. This dynamic is expected to continue to drive recovery in the national income over the rest of the year. Continued ample international liquidity, an acceleration in vacci¬nation programs, and low interest rates can also be ex¬pected to favor economic activity. Improved performance in the second quarter, which led to an upward growth revision for all components of spending, is expected to continue, with the economy returning to 2019 production levels at the end of 2021, earlier than estimated in the April report. This forecast continues to account for the short-term effects on aggregate demand of a tax reform package along the lines of what is currently being pro-posed by the national government. Given the above, the central forecast scenario in this report projects growth in 2021 of 7.5% and in 2022 of 3.1% (Graph 1.1). In this scenar¬io, economic activity would nonetheless remain below potential. The noted improvement in these projections comes with a high degree of uncertainty. Annual inflation increased more than expected in June (3.63%) as a result of changes in food prices, while growth in core inflation (1.87%) was similar to projections.

In the second quarter, annual inflation (9.67%), the technical staff’s projections and its expectations continued to increase, remaining above the target. International cost shocks, accentuated by Russia's invasion of Ukraine, have been more persistent than projected, thus contributing to higher inflation. The effects of indexation, higher than estimated excess demand, a tighter labor market, inflation expectations that continue to rise and currently exceed 3%, and the exchange rate pressures add to those described above. High core inflation measures as well as in the producer price index (PPI) across all baskets confirm a significant spread in price increases. Compared to estimates presented in April, the new forecast trajectory for headline and core inflation increased. This was partly the result of greater exchange rate pressure on prices, and a larger output gap, which is expected to remain positive for the remainder of 2022 and which is estimated to close towards yearend 2023. In addition, these trends take into account higher inflation rate indexation, more persistent above-target inflation expectations, a quickening of domestic fuel price increases due to the correction of lags versus the parity price and higher international oil price forecasts. The forecast supposes a good domestic supply of perishable foods, although it also considers that international prices of processed foods will remain high. In terms of the goods sub-basket, the end of the national health emergency implies a reversal of the value-added tax (VAT) refund applied to health and personal hygiene products, resulting in increases in the prices of these goods. Alternatively, the monetary policy adjustment process and the moderation of external shocks would help inflation and its expectations to begin to decrease over time and resume their alignment with the target. Thus, the new projection suggests that inflation could remain high for the second half of 2022, closing at 9.7%. However, it would begin to fall during 2023, closing the year at 5.7%. These forecasts are subject to significant uncertainty, especially regarding the future behavior of external cost shocks, the degree of indexation of nominal contracts and decisions made regarding the domestic price of fuels. Economic activity continues to outperform expectations, and the technical staff’s growth projections for 2022 have been revised upwards from 5% to 6.9%. The new forecasts suggest higher output levels that would continue to exceed the economy’s productive capacity for the remainder of 2022. Economic growth during the first quarter was above that estimated in April, while economic activity indicators for the second quarter suggest that the GDP could be expected to remain high, potentially above that of the first quarter. Domestic demand is expected to maintain a positive dynamic, in particular, due to the household consumption quarterly growth, as suggested by vehicle registrations, retail sales, credit card purchases and consumer loan disbursement figures. A slowdown in the machinery and equipment imports from the levels observed in March contrasts with the positive performance of sales and housing construction licenses, which indicates an investment level similar to that registered for the first three months of the year. International trade data suggests the trade deficit would be reduced as a consequence of import levels that would be lesser than those observed in the first quarter, and stable export levels. For the remainder of the year and 2023, a deceleration in consumption is expected from the high levels seen during the first half of the year, partially as a result of lower repressed demand, tighter domestic financial conditions and household available income deterioration due to increased inflation. Investment is expected to continue its slow recovery while remaining below pre-pandemic levels. The trade deficit is expected to tighten due to projected lower domestic demand dynamics, and high prices of oil and other basic goods exported by the country. Given the above, economic growth in the second quarter of 2022 would be 11.5%, and for 2022 and 2023 an annual growth of 6.9% and 1.1% is expected, respectively. Currently, and for the remainder of 2022, the output gap would be positive and greater than that estimated in April, and prices would be affected by demand pressures. These projections continue to be affected by significant uncertainty associated with global political tensions, the expected adjustment of monetary policy in developed countries, external demand behavior, changes in country risk outlook, and the future developments in domestic fiscal policy, among others. The high inflation levels and respective expectations, which exceed the target of the world's main central banks, largely explain the observed and anticipated increase in their monetary policy interest rates. This environment has tempered the growth forecast for external demand. Disruptions in value chains, rising international food and energy prices, and expansionary monetary and fiscal policies have contributed to the rise in inflation and above-target expectations seen by several of Colombia’s main trading partners. These cost and price shocks, heightened by the effects of Russia's invasion of Ukraine, have been more prevalent than expected and have taken place within a set of output and employment recovery, variables that in some countries currently equal or exceed their projected long-term levels. In response, the U.S. Federal Reserve accelerated the pace of the benchmark interest rate increase and rapidly reduced liquidity levels in the money market. Financial market actors expect this behavior to continue and, consequently, significantly increase their expectations of the average path of the Fed's benchmark interest rate. In this setting, the U.S. dollar appreciated versus the peso in the second quarter and emerging market risk measures increased, a behavior that intensified for Colombia. Given the aforementioned, for the remainder of 2022 and 2023, the Bank's technical staff increased the forecast trajectory for the Fed's interest rate and reduced the country's external demand growth forecast. The projected oil price was revised upward over the forecast horizon, specifically due to greater supply restrictions and the interruption of hydrocarbon trade between the European Union and Russia. Global geopolitical tensions, a tightening of monetary policy in developed economies, the increase in risk perception for emerging markets and the macroeconomic imbalances in the country explain the increase in the projected trajectory of the risk premium, its trend level and the neutral real interest rate1. Uncertainty about external forecasts and their consequent impact on the country's macroeconomic scenario remains high, given the unpredictable evolution of the conflict between Russia and Ukraine, geopolitical tensions, the degree of the global economic slowdown and the effect the response to recent outbreaks of the pandemic in some Asian countries may have on the world economy. This macroeconomic scenario that includes high inflation, inflation forecasts, and expectations above 3% and a positive output gap suggests the need for a contractionary monetary policy that mitigates the risk of the persistent unanchoring of inflation expectations. In contrast to the forecasts of the April report, the increase in the risk premium trend implies a higher neutral real interest rate and a greater prevailing monetary stimulus than previously estimated. For its part, domestic demand has been more dynamic, with a higher observed and expected output level that exceeds the economy’s productive capacity. The surprising accelerations in the headline and core inflation reflect stronger and more persistent external shocks, which, in combination with the strength of aggregate demand, indexation, higher inflation expectations and exchange rate pressures, explain the upward projected inflation trajectory at levels that exceed the target over the next two years. This is corroborated by the inflation expectations of economic analysts and those derived from the public debt market, which continued to climb and currently exceed 3%. All of the above increase the risk of unanchoring inflation expectations and could generate widespread indexation processes that may push inflation away from the target for longer. This new macroeconomic scenario suggests that the interest rate adjustment should continue towards a contractionary monetary policy landscape. 1.2. Monetary policy decision Banco de la República’s Board of Directors (BDBR), at its meetings in June and July 2022, decided to continue adjusting its monetary policy. At its June meeting, the BDBR decided to increase the monetary policy rate by 150 basis points (b.p.) and its July meeting by majority vote, on a 150 b.p. increase thereof at its July meeting. Consequently, the monetary policy interest rate currently stands at 9.0% . 1 The neutral real interest rate refers to the real interest rate level that is neither stimulative nor contractionary for aggregate demand and, therefore, does not generate pressures that lead to the close of the output gap. In a small, open economy like Colombia, this rate depends on the external neutral real interest rate, medium-term components of the country risk premium, and expected depreciation. Box 1: A Weekly Indicator of Economic Activity for Colombia Juan Pablo Cote Carlos Daniel Rojas Nicol Rodriguez Box 2: Common Inflationary Trends in Colombia Carlos D. Rojas-Martínez Nicolás Martínez-Cortés Franky Juliano Galeano-Ramírez Box 3: Shock Decomposition of 2021 Forecast Errors Nicolás Moreno Arias