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Formation de l'interface Fe/SrTiO₃(001) : propriétés électroniques et structurales / Formation of the Fe/SrTiO₃(001) interface : electronic and structural propertiesCatrou, Pierre 26 November 2018 (has links)
Les oxydes de métaux de transition sont d'un grand intérêt en raison du large éventail de propriétés qu'ils présentent. Ils ont potentiellement de nombreuses applications technologiques dans le domaine de l'électronique, reposant en partie sur le développement de dispositifs pour la technologie de l'information nécessitant de les contacter avec des métaux. Ce travail de thèse, basé principalement sur l'utilisation de la spectroscopie de photoémission, porte sur une étude détaillée de l'interface Fe/SrTiO₃ réalisée à température ambiante, dans laquelle nous nous sommes intéressés en particulier aux propriétés structurales et électroniques. Nous montrons que le fer est épitaxié, que sa croissance est en îlots et que les films couvrent entièrement le substrat pour le dépôt de quelques monocouches atomiques. Nous mettons en évidence une réaction du métal avec le substrat lors de la formation de l'interface qui se manifeste par la présence de titane réduit à l'interface. Nous associons cette réduction du titane à la présence de lacunes d'oxygène à l'interface Fe/SrTiO₃. Alors que la hauteur de barrière Schottky attendue pour une jonction abrupte Fe/SrTiO₃(001) est d'environ 1 eV pour les électrons, nous montrons que la présence des lacunes d'oxygène à l'interface abaisse la hauteur de barrière Schottky à environ 0,05 eV. La création de lacunes d'oxygène lors du dépôt de fractions de monocouche de fer sur le SrTiO₃ conduit aussi à une métallisation de la surface du semi-conducteur. Ce mécanisme est relié à la création d'états donneurs chargés positivement associés aux lacunes d'oxygène pendant le dépôt. Pour déterminer le profil de bande dans le substrat nous avons résolu l'équation de Poisson à une dimension dans une approche de la théorie de la fonctionnelle de la densité modifiée, en tenant compte de la couche d'accumulation d'électrons. Confrontant ces calculs avec nos résultats de photoémission nous trouvons que le potentiel de surface présente des inhomogénéités spatiales parallèlement à la surface. / Transition metal oxides are of great interest because of the wide range of properties they exhibit. They have potentially many technological applications in the field of electronics, especially based on the development of devices for information technology requiring contacting these oxides with metals. This thesis work, mainly based on photoemission spectroscopy, is a detailed study of the Fe/SrTiO₃ interface grown at room temperature in which we focus in particular on structural and electronic properties. We show that iron has an epitaxial growth with an island morphology and that films completely cover the substrate for the deposition of few atomic monolayers. We demonstrate that the metal reacts with the substrate during the formation of the interface which results in the presence of reduced titanium at the interface. We associate this reduction of titanium with the presence of oxygen vacancies at the Fe/SrTiO₃ interface. While the expected Schottky barrier height for a Fe/SrTiO₃(001) abrupt junction is about 1 eV for electrons, we show that the presence of oxygen vacancies at the interface lowers this Schottky barrier height to about 0.05 eV. The creation of oxygen vacancies during the deposition of fractions of iron monolayer on SrTiO₃ also leads to the metallization of the semiconductor surface. This mechanism is related to the creation of positively charged donor states associated with oxygen vacancies during deposition. To determine the band profile in the substrate, we solved the one-dimensional Poisson equation in a modified approach of the density functional theory taking into account the electron accumulation layer. By comparing these calculations with our photoemission results, we find that the surface potential has spatial inhomogeneities parallel to the surface.
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The remembrance path: searching for the lost memory of the people who escaped from the "Red China".January 2005 (has links)
Hong Ka Yu Garret. / "Architecture Department, Chinese University of Hong Kong, Master of Architecture Programme 2004-2005, design report."
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Influence des hétérogénéités métallurgiques sur les processus de diffusion et de piégeage de l'hydrogène dans le nickel / Influence of metallurgical heterogeneities on the mechanisms of hydrogen diffusion and trapping of in nickelOudriss, Abdelali 11 December 2012 (has links)
Une large investigation sur l’influence de plusieurs défauts métallurgiques sur les processus de diffusion et de piégeage de l’hydrogène a été conduite sur le nickel. Ce travail a été réalisé selon deux orientations scientifiques. Une première approche a consisté à évaluer l’impact des défauts intrinsèques et plus particulièrement les joints de grains et les dislocations géométriquement nécessaires sur les modes de transport et de ségrégation de l’hydrogène. Le couplage de caractérisations microstructurales avec les essais de perméation électrochimiques et de thermo-désorption a permis d’établir que les joints de grains présentant une structure ordonnée appelés « spéciaux » représentent des zones privilégiées à la ségrégation de l’hydrogène. Une seconde catégorie de joints de grains dits « généraux » ou « random » présentant un excès de volume important constituent des promoteurs à la diffusion de l’hydrogène. Ces derniers sont la principale source des phénomènes de courts-circuits de diffusion relatés dans les matériaux cubiques à faces centrées. La seconde approche de cette étude a consisté en l’étude de l’interaction de l’hydrogène avec les hétérogénéités de déformation plastique. Les essais de perméation électrochimique réalisés sur des microstructures obtenues par déformation ont montré qu’en traction monotone, les cellules équiaxes et les murs de dislocations représentent des pièges pour l’hydrogène. Celles-ci ralentissent son transport. Ce dernier est essentiellement assuré par le mécanisme de diffusion interstitielle. Par ailleurs, pour la microstructure de déformation résultant de l’essai en fatigue, une accélération de la diffusivité de l’hydrogène a été enregistrée ce qui suggère qu’un phénomène comparable au court-circuit de diffusion intervient dans le transport de l’hydrogène. Concernant les deux approches, les résultats obtenus suggèrent une contribution de l’hydrogène dans la formation de lacunes. / A thorough investigation on the influence of several metallurgical defects on the hydrogen diffusion and trapping was conducted on nickel. This work was conducted towards two scientific orientations. A first approach was to assess the impact of intrinsic defects, especially grain boundaries and geometrically necessary dislocations on the hydrogen transport and segregation mechanisms. Combining microstructural characterizations with electrochemical permeation tests and thermal desorption spectroscopy, it has established that the grain boundaries with ordered structure called "special grain boundaries" are preferential areas for hydrogen segregation. On the other hand, a second category of grain boundaries called "general" or "random" with high free volume and disordered structure are promoters for hydrogen diffusion, and they represent the main sources of the phenomena short-circuit diffusion reported in the face-centered cubic materials. The second approach of this work consisted in the study of the interaction of hydrogen with the plastic deformation heterogeneities. The electrochemical permeation tests performed on microstructures obtained by deformation showed that for the traction monotonous, the equiaxed cells and walls of dislocations are the potential traps for hydrogen and they slow its transport, this latter is mainly provided by the interstitial diffusion mechanism. In addition, for fatigue microstructure, rapid diffusivity of hydrogen was recorded, and suggesting that a phenomenon similar to short-circuit diffusion is involved in the transport of hydrogen. On two approaches, the results suggest a contribution of hydrogen in the formation of vacancies
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No limiar dos Impérios: projetos, circulações e experiências na fronteira entre a Capitania do Rio Negro e a Província de Maynas (c.1780-c.1820) / On the threshold of Empires: projects, circulations and experiences in the border area between the Captaincy of Rio Negro and the Province of Maynas (1780-1820)Carlos Augusto de Castro Bastos 24 September 2013 (has links)
Esta tese analisa as políticas destinadas à área fronteiriça entre a Capitania do Rio Negro e a Província de Maynas, bem como as circulações e experiências que caracterizaram esse espaço amazônico. O recorte cronológico abarca, inicialmente, os trabalhos de demarcação de limites empreendidos por representantes das Coroas espanhola e portuguesa, na década de 1780, compreendendo ainda os anos de crise política do Antigo Regime e a eclosão dos movimentos de independência na América nas primeiras décadas do século XIX. Nesse trabalho, privilegia-se uma análise que atente para as relações transfronteiriças, os impactos no espaço em questão das grandes transformações vivenciadas pelos impérios ibéricos e as leituras, interpretações e ações gestadas pelos sujeitos que habitavam essa fronteira ibero-americana. / This thesis examines the policies concerning the border area between the Captaincy of Rio Negro and the Province of Maynas, as well as the circulations and experiences that characterize this Amazonian space. Initially, the chronological period considered includes the demarcation of boundaries undertaken by representative members of the Spanish and Portuguese crowns in the 1780s, the years of political crisis of the Old Regime, and the outbreak of the independence movements in America in the early decades of the XIXth century. In this work, the analysis attempts to cross-border relations, the impacts this space has suffered due to great changes experienced by the Iberian empires, and also, the readings, interpretations and actions generated by the subjects who inhabited this Iberoamerican frontier.
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Vibrações não lineares em tubulações com fluido em escoamento / Nonlinear movement in fluid flow pipesPrado, Joaquim Orlando 21 June 2013 (has links)
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Previous issue date: 2013-06-21 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / In this work, the linear and nonlinear instability of pipes conveying static and pulsating fluid flow is analyzed. The dynamic equation of motion was derived for cantilevered and clamped-clamped pipes. For this purpose, the Euler Bernoulli beam theory and Hamilton’s principle were applied, resulting in a partial differential equation of second order in time. Thus, a model with four degrees of freedom, which satisfies the boundary condition, is used and, the Galekin method is applied to derive the set of coupled non linear ordinary equations of motion which are, in turn, solved by the fourth order Runge-Kutta method, and then some numerical results were obtained as Argand diagram, stability boudaries, time response, phase plane and, Poincaré section, through computational algorithms modeled in C++. These results revealed the importance of the nonlinear terms in the stability of the system, especially in the post-critical analysis, also revealed the existence of quasi-periodic motions, for the system subjected to a static flow and, chaotic motions for pulsating fluid flow / Nesta dissertação analisa-se a instabilidade linear e não linear de tubos com fluido interno em escoamento estático e pulsante. A equação de movimento dinâmico foi deduzida para tubos em balanço e biengastados. Para tanto, utilizou-se a teoria de vigas de Euler Bernoulli e o princípio variacional de Hamilton, resultado em uma equação diferencial parcial de segunda ordem no tempo. Tal equação foi discretizada, pelo método de Galerkin, em quatro equações diferenciais ordinárias, uma para cada grau de liberdade, em seguida transformadas em um conjunto de equações diferenciais de primeira ordem. Tais equações foram integradas pelo método de Runge-Kutta de quarta ordem e, posteriormente, foram obtidos alguns resultados numéricos como: diagrama de Argand, curvas de escape, diagrama de bifurcação, resposta no tempo, plano fase e, seção de Poincaré, através de algoritmos implementados computacionalmente na linguagem C++. Tais resultados revelaram a importância dos termos não lineares na estabilidade do sistema, especialmente na análise pós-crítica, revelaram também a existência de movimentos quase periódicos, para o sistema submetido a um fluxo estático e, caóticos para fluxo pulsante.
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Avaliação de Variáveis para Delimitação de Áreas Protegidas Costeiras e Marinhas: sugestão de limites para uma Unidade de Conservação costeira de Uso Sustentável na região das Reentrâncias Maranhenses (Estado do Maranhão, Brasil) / Evaluation of variable for Delimitation of Areas Coastal and Sea proteges: suggestion of limits for a Unit of coastal Conservation of Sustainable Use in the region of the Maranhão Reentrances (State of the Maranhão, Brazil)Fukuda, Juliana Cristina 30 November 2006 (has links)
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Previous issue date: 2006-11-30 / The protected areas (PAs) for nature conservation are important tools for maintaining
ecological function and biodiversity conservation in a determined region. Specific laws
for their protection are applied in the defined space within their limits. Thus, considering
boundaries definition as a characteristic of fundamental importance to reach the goals
for which the protected area has been created, in this work we aimed to evaluate socioeconomic-
cultural and environmental features, and also management and political
variables for suggesting boundaries to a marine costal protected area (MCPA) in the
Reentrâncias Maranhenses region, with special attention to the municipality of Porto
Rico do Maranhão. This portion of coast is characterized for its high nutrients levels,
macro-tidal regimes, large continental shelf and exuberant mangroves, and the
artisanal fishing as the main economic activity. We limited the purpose of this study to
the managed MCPAs. We used interviews, field observations, water and sediment
samples and secondary information to reach the following goals: 1) survey on the
MCPAs in Brazil, analysing the management difficulties answered by their managers
related to the boundaries definition; 2) discussion whether to create a new protected
area in the region and its advantages; 3) characterize the local fishery and the direct
users of fishery resources; 4) make a list of vertebrates species (not including
herpetofauna) and benthos species which have occurrence indication in the area; 5)
classify the local environments based on orbital images and field work; 6) sample
estuarine waters for physical and chemical analysis; 7) consider land tenure, fishery
management and navigation safety issues. The main contributions of this work are: a)
information on 141 publicly managed coastal and marine protected areas; b)
confirmation that in the older protected areas there have been fewer studies on
boundary definition, in inverse proportion to current occurrence of management
problems. These studies have been more frequent in the Extractive Reserves than in
the Environmental Protected Areas; c) indications of an unsustainable fishery, socially,
economically and environmentally endangering the region; d) occurrence indication of
89 fish morphospecies, 25 of shore birds and 6 of mammals, emphasizing the ones in
danger of extinction; e) elaboration and analysis of a multi-criteria matrix to indicate the
most important environments for protection; f) indication of an ideal area for
protection, only considering environmental concepts and indication of an area we
believe would be the most suitable for a PA, considering the other management
variables. Yet, this suggestion must be discussed with all the stakeholders, in a
consistent effort to make aware and empower the users so that they realize that the
conflicts and problems will only be minimized with stakeholder participation and
commitment to the issue. / As Unidades de Conservação (UCs) áreas protegidas para conservação da natureza
são importantes instrumentos para conservação da biodiversidade e dos recursos
ambientais de determinada região. Legislações específicas para sua proteção se
aplicam ao espaço definido pelos seus limites. Desta forma, considerando a
delimitação de uma UC como característica de fundamental importância para atingir os
objetivos pelas quais a área foi criada, buscamos neste trabalho avaliar características
ambientais e sócio-econômico-culturais, bem como variáveis políticas e de gestão,
para sugerir limites para uma Unidade de Conservação costeiro-marinha (UCCM) na
região das Reentrâncias Maranhenses, com especial atenção à região do município de
Porto Rico do Maranhão. Esta porção da costa é caracterizada pelo alto aporte de
nutrientes, regime de macro-marés, plataforma continental larga e manguezais
exuberantes, sendo a pesca artesanal a principal atividade econômica. O escopo
deste trabalho foi limitado às UCCMs de uso sustentável. Através de entrevistas,
observações de campo, coleta de água e sedimento, e dados secundários, realizaramse:
1) levantamento das UCCMs de uso sustentável do Brasil, analisando-se as
dificuldades de gestão relacionadas aos limites da área, de acordo com seus atuais
gestores; 2) discussão sobre a necessidade e vantagens de se criar uma nova UC na
região; 3) caracterização da pesca e dos usuários diretos dos recursos pesqueiros na
região; 4) listagem das espécies de vertebrados (exceto herpetofauna) e de bentos de
ocorrência na área; 5) classificação de ambientes lcoais com base em imagens
orbitais e trabalho de campo; 6) amostragem de águas estuarinas para análises físicoquímicas;
7) considerações referentes a questões fundiárias, de pesca e de segurança
da navegação. Como principais contribuições deste trabalho citam-se: a) levantamento
de dados referentes a 141 UCCMs de uso sustentável, exceto RPPNs; b) confirmação
de que as UCs mais antigas tiveram menos estudos para delimitação da área a ser
protegida, em proporção inversa à ocorrência de problemas de gestão atuais. Entre as
Reservas Extrativistas os estudos foram mais freqüentes do que entre as Áreas de
Proteção Ambiental; c) demonstração de indícios de insustentabilidade da atividade
pesqueira, com comprometimento social, econômico e ambiental da região; d)
indicação de ocorrência de 89 morfoespécies de peixes, 25 de aves costeiras e 6 de
mamíferos, destacando-se espécies ameaçadas de extinção; e) elaboração e análise
de uma matriz-multi-critérios, para indicar ambientes mais importantes para proteção;
f) indicação de uma área ideal para proteção, considerando apenas conceitos
ambientais, e de uma área que acreditamos ser a mais adequada para a uma UC,
considerando demais variáveis de gestão. Esta proposta deve ainda ser discutida
juntamente com todos os grupos interessados, em um esforço consistente de
conscientização dos usuários e empoderamento dos mesmos, assim como promoção
de alternativas de geração de renda, de forma que eles percebam que os conflitos
existentes só serão minimizados com a própria participação e comprometimento da
comunidade interessada em relação à questão.
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FRONTEIRAS DO CAMPO RELIGIOSO: ADAPTAÇÕES AO MERCADO DE BENS SIMBÓLICOSVelasco, Leonardo Rodrigues de 22 August 2018 (has links)
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Previous issue date: 2018-08-22 / VELASCO, Leonardo Rodrigues de. Borders of the religious field: Adaptations to the
market of symbolic goods.Master's Dissertation (Post-graduation Program in Religion
Sciences) - Pontificia Universidade Católica de Goiás, 2018.
This research intends to analyze the displacement of the religious field in the Brazilian
symbolic goods market. Starting from an investigation of the concept of religious field
as proposed by Pierre Bourdieu, we demonstrate how the boundaries of this field
deteriorate nowadays with the entry of new agents and techniques. For such, we
analyze five distinguished religious agents – Priest Marcelo Rossi, Priest Fábio de
Melo, Augusto Cury, Cristiano Cardoso e Renato Cardoso –, proving how they – by
using digital media or self-help literature – can offer their symbolic goods to the demand
of individuals in search of beliefs. That said, we have traditional institutions and new
agents that, dealing with the liquidity of post-modernity, create and reconfigure models
to reach the individuals search for affirmation in the world. Through those
considerations, we aim to show how the individual’s subjectivity dictates the course of
the symbolic goods offer in the religious field. Finally, we intend to contribute, by means
of examples in the Brazilian context, with the view that the actual Western society goes
through considerable reconfigurations, which question the notion itself of religious
field. / VELASCO, Leonardo Rodrigues de. Fronteiras do campo religioso: daptações ao
mercado de bens simbólicos. Dissertação de Mestrado (Programa de Pós-graduação
em Ciências da Religião) – Pontifícia Universidade Católica de Goiás, 2018.
Esta pesquisa tem como propósito analisar o deslocamento do campo religioso no
mercado de bens simbólicos brasileiro. Partindo de uma investigação do conceito de
campo religioso proposto por Pierre Bourdieu, demonstramos como as fronteiras
desse campo se deterioram na atualidade com a entrada de novos agentes e novas
técnicas. Para tal, analisamos cinco agentes do religioso diferentes – Pe. Marcelo
Rossi, Pe. Fábio de Melo, Augusto Cury, Cristiane Cardoso e Renato Cardoso –
comprovando como estes – por meio do uso de mídias digitais ou de literatura de
autoajuda – conseguem ofertar seus bens simbólicos à demanda de indivíduos em
busca de crenças. Isto posto, temos instituições tradicionais e novos agentes que,
lidando com a liquidez da pós-modernidade, criam e reconfiguram modelos para
atingir à busca por afirmação dos indivíduos no mundo. Mediante tais considerações,
buscamos apresentar como a subjetividade do indivíduo dita os rumos das ofertas de
bens simbólicos no campo religioso. Finalmente pretendemos contribuir, por meio de
exemplos do contexto brasileiro, com a visão de que a sociedade ocidental atual passa
por reconfigurações consideráveis, que questionam a própria noção de campo
religioso.
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Desecration, Moral Boundaries, and the Movement of Law: The Case of Westboro Baptist ChurchBaker, Joseph O., Bader, Christopher D., Hirsch, Kittye 02 January 2015 (has links)
Using participant observation, in-depth interviews, and legislative histories, we examine Westboro Baptist Church, a religious group infamous for homophobic rhetoric and funeral protests. Employing cultural and interactionist perspectives that focus on the semiotics of death, the sacred, and desecration, we outline how Westboro’s activities purposively violate deeply held signifiers of moral order through language, while simultaneously respecting extant laws of behavior. This strategy, in conjunction with the political profitability of opposing the group, explains why the group’s activism triggered extensive legal disputes and modifications at multiple levels of governance. Westboro’s actions and use of symbols—and those of others against the group—lay bare multiple threads in the sacred cultural fabric of American society.
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Der östliche WestenFaridzadeh, Sara 07 November 2019 (has links)
Diese Dissertation handelt von Grenz- und Fremdheitskonstruktionen in iranischen Reiseberichten (sowohl Europa- als auch Russlandreiseberichte) des 19. Jahrhunderts. Durch die Untersuchung der zentralen sozialen und kulturellen Strukturen und Prozesse der Grenz- und Fremdheitserzeugung ist in dieser Studie, die iranische Gesellschaft, in den Besonderheiten ihrer eigenen Geschichte, durch ihre äußeren Begegnungen und Interdependenzen geforscht worden. Anhand der theoretischen Fokussierung auf zwei Konzepte, nämlich Fremdheit und kulturelle und soziale Grenze, wurde die Entwicklung der iranischen Gesellschaft in Anbetracht ihrer Beziehung zu den europäischen Ländern im Laufe des 19. Jahrhunderts rekonstruiert. Zwar ist die Arbeit primär eine soziologische Studie, konnte aber den historischen Kontext der Ereignisse und die literarische Beschaffenheit der Reisetexte nicht unbeachtet lassen. / This work is a comprehensive sociological study on travelogues, specifically with focus on the Iran’s 19th century history (Qajar Dynasty). It presents an analysis that sociologically and systematically registers the staging of cultural boundaries and the socio-historical construction of foreignness in the Iranian society, on the basis of selected Persian travel literature. This study has tried to show that cultural and social boundaries are relational and historical constructs which, in case of Iran, are dramatically affected by the encounters of Iranians (statesmen, students, tourists, etc.) with western countries (Western Europe and Russia).
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Environmental Gradients, Community Boundaries, and Disturbance the Darlingtonia Fens of Southwestern OregonTolman, Deborah A. 01 January 2004 (has links)
The Darlingtonia fens, found on serpentine soils in southern Oregon, are distinct communities that frequently undergo dramatic changes in size and shape in response to a wide array of environmental factors. Since few systems demonstrate a balance among high water tables, shallow soils, the presence of heavy metals, and limited nutrients, conservative efforts have been made to preserve them. This dissertation investigates the role of fire on nutrient cycling and succession in three separate fens, each a different time since fire. I specifically analyze the spatial distributions of soil properties, the physical and ecological characteristics of ecotones between Jeffrey pine savanna and Darlingtonia fens, and the vegetation structure of fire-disturbed systems. Soil, water, and vegetation sampling were conducted along an array of transects, oriented perpendicular to community boundaries and main environmental gradients, at each of the three fens. Abrupt changes in vegetation, across communities, were consistently identified at each of the three sites, although statistical analysis did not always identify distinct mid-canopy communities. Below-ground variables were likewise distinguished at the fen and savanna boundary for two of the three sites. At the third site, discontinuities did not align with the fen boundaries, but followed fluctuations in soil NH4. My results suggest that below-ground discontinuities may be more important than fire at preserving these uniquely-adapted systems, while vegetation undergoes postfire succession from fen to mid-canopy to savanna after approximately 100 years since fire. Although restoration of ecosystem structure and processes was not the primary focus of this study, my data suggest that time since fire may drive ecosystem processes in a trajectory away from the normal succession cycle. Moreover, time since fire may decrease overall vigor of Darlingtonia populations.
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