Northern peatlands are an important component of the global carbon (C) cycle and have been a net sink of atmospheric C during the Holocene. Under current climate warming conditions, the future sink-source balance of these peatlands is uncertain. In particular, peatlands near the southern limit of permafrost are likely to be sensitive to changes in topography as well as climate. In order to predict how the sink-source balance may change, this thesis focuses on determining the generality of observed patterns of C accumulation in Northeastern Canada. The methodological approach in this thesis is unique. A total of 30 cores were taken from 9 peatlands located in 3 ecoclimatic regions along the North Shore of the Gulf of St Lawrence. This replication of records allows for climate-scale (allogenic) signals to be separated from the internal or local factors (autogenic), and for statistical testing of differences between regions and within sites over time. Trends in carbon accumulation rates (CAR) were analysed on three levels: (1) within individual sites along a hydrological or microtopography gradient, (2) between overall regions located along a climatic or permafrost gradient, and (3) over time on a multi-centennial scale. Lead-210 (210Pb) dating was used throughout the analysis to increase temporal resolution for the last 150-200 years of C accumulation. The method was thoroughly tested from preparation to analysis and found to produce reliable results, comparable with other dating methods. These dates were then used to develop combined age-depth models for longer-term context. Replicated records of 210Pb inventories and fallout rates were also used to address questions of deposition patterns and post-depositional mobility in peat profiles. Total inventories decreased with water table depth, with lichen hummocks having significantly higher inventories. One site also received significantly higher 210Pb deposition than the other two, as it is more sheltered from the Gulf influence. Recent carbon accumulation rates for the 150-year period for all microforms across all regions was 62.1 ± 4.4 g C m-2 a-1, and were highest for Sphagnum hummocks (79.9 ± 8.9 g C m-2 a-1) and lowest for dry lichen hummocks (42.7 ± 6.2 g C m-2 a-1). Patterns and trends at this scale were mainly driven by autogenic processes, including incomplete decomposition in the acrotelm peat. Models of peat accumulation related to acrotelm thickness were found to be overly simplistic, as carbon accumulation for intermediate microforms showed large natural variability driven by changing ecohydrological feedbacks, in part due to permafrost degradation at one of the sites. Over a multi-centennial scale, carbon accumulation rates were driven by a combination of climatic changes and ecohydrological feedbacks due to shifts in the microform configuration in response to permafrost degradation. Changes in carbon accumulation rates were detected and coincided with Little Ice Age temperature/solar minima (including the Spörer, Maunder and Dalton Minima), permafrost degradation since the 1950s, and recent climatic changes in the mid-1990s. Snow cover and exposure of sites and microforms were found to play an important role, rather than solely climatic variables. Rapid Sphagnum re-establishment in post-permafrost degraded features and increasing temperatures meant that carbon accumulation was highest for the northernmost site in the transect. Age-depth models using a combination of lead-210 and radiocarbon dates allowed for the calculation of carbon accumulation rates at a decadal resolution. While peat carbon sequestration is projected to increase in northern regions, the fate of peatland C near the southern limit of permafrost is complex. Future studies seeking to interpret recent changes should include multiple cores and consider both regional climatic and local ecohydrological drivers.

Sunnisme et Shiisme en dialogue : Etude comparative de deux professions de foi : Maḥmûd Šaltût (1959) et Ğa‘far al-Subḥânî (1998)L’islam actuel connaît deux grandes familles de musulmans dont les doctrines, les pratiques et les structures font qu’elles s’expriment à travers des formes contrastées tout en prétendant, l’une et l’autre, à en être l’unique représentant orthodoxe. La majorité des musulmans s’affirment sunnites, une minorité importante dont les membres se disent šî‘ites. A bien interroger la longue histoire de l’islam depuis ses origines, force est de constater, encore aujourd’hui, qu’il s’agit là des prolongements actuels d’une première fracture de la communauté musulmane qui se produisit pour des raisons de continuité du charisme prophétique et de légitimité du pouvoir religieux, fracture qui n’a jamais cessé de se manifester, au cours des siècles, sous des formes politiques, théologiques ou dévotionnelles. Et puisque l’affrontement s’exprime à nouveau aujourd’hui sous toutes ces formes, qu’elles soient politiques, théologales ou dévotionnelles, il nous a semblé intéressant de proposer un état de la situation actuelle du point de vue des dogmes. Pour ce faire, il nous a paru utile d’interroger et de comparer, en la présente thèse, deux traités plus ou moins contemporains qui en proposent les doctrines respectives en vue d’y discerner ce qu’elles ont en commun et ce qui les distingue spécifiquement. La ‘aqîda (credo) sunnite du Šayḫ égyptien Maḥmûd Šaltût, al-Islâm, ‘aqîda wa-šarî‘a (L’islam, credo et loi) (1959) est donc ici confrontée au traité du ‘Allâma iranien, Ğa‘far al-Subḥânî, al-‘Aqîda l-islâmiyya ‘alâ ḍaw’ madrasat Ahl al-Bayt (Le credo islamique à la lumière de l’école des Gens de la Maison) (2012). C’est pourquoi nous avons choisi, pour titre de cette thèse, « Sunnisme et Šî‘isme en dialogue », bien que les deux professions de foi présentées ici ne soient pas explicitement consacrées à cette question. Il apparaît néanmoins, au vu des parcours de leurs auteurs respectifs, qu’elle ne pouvait être étrangère à leurs préoccupations lorsqu’ils les ont rédigées. Notre initiative consistera seulement à « resituer » leurs grandes idées et leurs démonstrations respectives dans le cadre de ce dialogue, dont il est certain qu’il a représenté pour eux l’horizon de leur idéal de rapprochement, tout en tenant compte de leur. Notre choix s’est porté sur deux ouvrages à la fois d’un accès relativement aisé et d’une représentativité au-dessus de tout soupçon. La 1ère partie de la thèse se devait de présenter d’abord les auteurs et leurs ‘aqîda-s. Pour bien connaître qui sont les auteurs ici étudiés, il convenait d’en proposer la biographie et la bibliographie en situant leur témoignage et leurs publications dans des contextes socio-politiques très différents. En revanche, pour mieux apprécier ce que représentent ces deux professions de foi, on a estimé nécessaire de rappeler ce qu’est, en règle générale, une ‘aqîda avant d’examiner nos deux textes rapidement analysés en leurs chapitres et paragraphes. Cette démarche permettra de rappeler brièvement les visages du sunnisme et du šî‘isme actuels dans leurs grandes lignes doctrinales, leurs méthodologies théologiques et leurs implications juridiques. Suite à cela, nous proposerons, avec le texte arabe en vis-à-vis, la traduction française du livre de Šaltût, puis celle d’al-Subḥânî. La 2ème partie, de loin la plus importante, compare ainsi le contenu des deux ‘aqîda-s ici analysées à partir de leurs traductions françaises. Une conclusion d’ensemble pourra alors être proposée en vue d’évaluer ce que sunnisme et šî‘isme ont en commun aujourd’hui après des évolutions qui les ont vus se rapprocher singulièrement l’un de l’autre. Il sera, par suite, possible d’apprécier les efforts entrepris par certains en vue de « rendre proches» (taqrîb) Sunnites et Ši‘ites au nom d’un oecuménisme intra-islamique. / Sunnism and Shiisme in dialoguea comparative study of the two professions of faith :Maḥmûd Šaltût (1959) et Ğa‘far al-Subḥânî (1998)Current Islam comprises two large families of Muslims, in which doctrines, practices, structures are being expressed in different contrasted forms, each one of the two families pretending to represent the unique orthodoxy. The great majority of Muslims declare themselves as « Sunnit », then an influential minority of members declare themselves as « Shiites »If we look into the history of Islam since its origin, we are led to notice that ,even to day, these are off- shoots of a deep fracture in the Muslim community, That fracture occurred on account of the continuity of the prophetic charism and of the legitimity of the religious power; Right through the centuries that fracture was apparent under different forms, political, theological, devotionnal.Since that confrontation appears in top-days's world, under different forms:political, theological, devotionnal, It appeared to us an interesting initiative to brush up a picture of the actual situation looking at it on the point of view of dogmas. To do that, it appeared useful to us to compare , in the present thesis, two treaties explaining the two doctrines , the idea is to discern what they have in common and what distinghishes one from the other. The « aqida »(creed)of the egyptian Sayh Mahmud Saltut; al -Islam, aqida wa sari'a (islamic creed and law) is in here confronted with the treaty of the iranian « Allama, Ga'far al Subhani (the islamic creed in the light of the school of « the people of the house » (2012). That is why we have chosen as title: »Sunnism and Shiisme in dialogue » in spite of the fact that the two professions of faith are not directely relevent to that question. Nevertheless it appears that , taking into account the development of thought of the authors, the idea was part of their preoccupations by the time they were written down.Our main concern here is to re-set their great ideas and demonstrations in the framework of this dialogue: it is clear that it was an attempt to bring together the two parties without minimizing their differences. Our choice fell on two treaties which are of a relatively easy access and the representativity of which is beyond doubts.In the first part of the thesis we had to present the authors and their « aqidas » In order to have a good knowledge of the authors, it was profitable to propose their biography, to give an account of the bibliography, in order to situate their testimony and their publications in the socio political set- up of their time. In order to appreciate what these professions of faith represent, we thought necessary to remind ourselves about what an « aqida » is, before we could examin both texts quickly analysed going through chapters and paragraphs. That approach will allow us to recall to mind the different faces of Sunnism and shiism, nowadays, along their doctrinal lines, their theological methods, their juridical implications. After that, we shall propose ,with the arabic translation in front of it, a French translation of Saltut's book and a translation of al Subhani's book.The second part is by far the most important, we shall compare the content of both « aqidas »books and analyse them as from their french translations. As a common conclusion we shall propose an evaluation of what sunnism and si'isme have in common to day, at the end of an avolution that had tendency to bring them together. After that, we shall be able to appreciate the efforts undertaken by some in order to bring closer Sunnites and Shiites, in the name of an intra-islamic oecumenism.

Although the impact of cannabinoids (CBs) on anxiety has been thoroughly studied, current research paradigms fail to incorporate acute stressors. The present study investigated the synthetic CB HU-210’s anxiolytic potential in an acute stress CD1 male mouse model, where the animals were subject to a 10-minute Forced Swimming (FS) test between treatment and behavioral tests. Surprisingly, HU-210 did not show anxiolytic action in the Open Field (OFT) and Elevated-Plus Maze (EPM) stressed mice as previously reported in the naïve model literature. The combination of acute stress and high HU-210 doses produced severe locomotor impairments in ambulatory movement that were not previously observed in unstressed mice. It is hypothesized that this anxiogenic phenotype results from the summation of exogenous CB treatment and stress-induced endocannabinoid (eCB) release. Subsequently, the impact of the eCB signaling on anxiety behaviors was examined. Systemic administration of KML29, the selective inhibitor of 2-AG degradative enzyme, returned stress-induced anxiety-like behaviors to baseline levels, without significantly affecting locomotion. KML29’s anxiolyticism was abolished when combined with the cannabinoid receptor antagonist AM281, implying this is a CB receptor-mediated process. A GABAA receptor agonist muscimol was co-administered with KML29 in order to pharmacologically investigate the role of GABAergic neurotransmission in this anxiolytic phenomenon, but it did not alter KML29’s effects. Collectively, these findings suggest that exogenous CBs and acute stress act synergistically in an anxiogenic manner, but that enhanced 2-AG signaling in response to stress demonstrates anxiolytic potential.

The software environment for power electronics design is comprised of tools that address many interrelated disciplines including circuits design, physical layout, thermal management, structural mechanics, and electromagnetics. This usually results in a number of separate models that provide various views of a design, each of which is usually stored separately in proprietary formats. The problem is that the relationships between views (e.g., the circuit design that defines the functional connectivity between components, and the physical layout that provides physical paths to implement connections), are not explicitly captured. This makes it difficult to synchronize and maintain data consistency across all models as changes are made to the respective views. This thesis addresses this problem by describing power electronics modules using STEP AP210, the STandard for the Exchange of Product data, Application Protocol 210; which has been designated as ISO 10303-210. A multidisciplinary model was implemented for an integrated power electronics module (IPEM). It consists of two views of the IPEM: a functional network definition of the IPEM, and a physical implementation that satisfies the functional connectivity requirements. The relationships between these two views are explicitly recorded in the model. These relationships allow for the development of a method which verifies whether the connectivity data in both views are consistent. Finally, this thesis provides guidance for deploying STEP AP210 to unify multidisciplinary data resources during the design of integrated power electronics. / Master of Science

No description available.

La communication entre les différentes organelles se fait par l’intermédiaire du trafic vésiculaire, un processus qui nécessite un remodelage continu des membranes. Les vésicules fortement courbées bourgeonnent d'un compartiment donneur et fusionnent avec un compartiment accepteur. Les protéines impliquées dans le bourgeonnement et fusion des vésicules ont été largement étudiées. Récemment, la découverte de détecteurs de courbure membranaire a révélé que le trafic membranaire pourrait être régulé à un niveau supplémentaire, par la détection de la forme de la membrane. Le premier détecteur de courbure membranaire identifié était le motif ALPS (Amphipathic Lipid Packing Sensor), qui a été trouvé dans un certain nombre de protéines de la voie sécrétoire précoce et l'enveloppe nucléaire. La protéine d’arrimage GMAP-210 localisé au niveau du cis-Golgi, est composée d’une longue superhélice (coiled-coil) et d’un motif ALPS à l'extrême N-terminale. Il a été démontré in vitro, que ce motif se replie et forme une hélice amphipathique capable de se fixer sur des petits liposomes. Toutefois, l'identité des vésicules, reconnues par ce détecteur de courbure dans la cellule, reste inconnue. α-Synucléine est une autre protéine qui se lie préférentiellement à des membranes très courbées. Cette protéine localisée sur les vésicules synaptiques, est impliquée dans la régulation du taux de vésicules au niveau des terminaisons nerveuses pré-synaptiques. Connue pour son rôle central dans le développement de la maladie de Parkinson, α-synucléine contient une région non structurée en solution, mais qui forme une hélice amphipathique au contact de petits liposomes in vitro. Les hélices amphipathiques formées par le motif ALPS et α-synucléine sont très différentes aussi bien sur le plan chimique que sur le plan conformationel. Le motif ALPS possède une face hydrophobe bien développée, mais un coté polair pauvre avec très peu de résidus chargés. α-Synucléine, en revanche, a un côté hydrophobe modéré, et une face polaire zwitterionique riche en résidus chargés. L'objectif principal du projet était de comparer les propriétés de liaison aux membranaires in vivo et in vitro de ces deux hélices amphipathiques de structure opposée. L’expression de ces deux sondes chez la levure, favorise l'accumulation de structures vésiculaires de propriétés différentes. L'extrémité N-terminale de la protéine GMAP-210 contenant son motif ALPS (GMAPN) co-localisé spécifiquement avec des marqueurs de la voie sécrétoire précoce, alors une sonde contenant une portion de l’hélice amphipathique d’α-synucléine co-localise avec des marqueurs endocytiques et post-Golgiens. La mutagenèse du motif ALPS et l'inversion de la séquence de ALPS dans GMAPN confirment que ce détecteur de courbure membranaire se fixe spécifiquement aux vésicules via des interactions directes protéines-lipides, plutôt que les interactions protéines-protéines. Notre analyse a montré que ces détecteurs de courbure mammifères, exprimés dans la levure préservent leur capacité à cibler des vésicules spécifiques, vésicules de la voie sécrétoire précoce pour les motifs ALPS, et vésicules d’endocytose/post-Golgi pour α-synucléine. La composition membranaire de ces vésicules correspond à la composition des liposomes fixés par le motif ALPS et α-synucléine in vitro. Les propriétés biochimiques opposées du motif ALPS et α-synucléine, sont parfaitement adaptés à chacun de ces deux environnements membranaires dans la cellule. Le programme HeliQuest est conçu pour identifier des hélices amphipathiques capables de se lier sur les membranes, y compris les motifs ALPS. Un nouveau module conçu pour identifier les hélices amphipathiques avec des propriétés similaires à α-synucléine a été récemment élaboré. Les recherches effectuées dans les bases de données de protéines de levure et humaines ont permis d’identifier des hélices amphipathiques candidats qui ont des propriétés similaires à α-synucléine, dans de nombreuses protéines. Nous avons préparé un ensemble de sondes, dans lequel ces hélices sont insérées à la fin de la superhélice de GMAPN. Une première étude de leur co-localisation dans les cellules de levure avec un ensemble de marqueurs démontre une localisation spécifique, ce qui suggère que ces hélices peuvent avoir la capacité de cibler des membranes de manière spécifique. D'autres travaux seraient nécessaires pour confirmer ou pas si ces hélices amphipathiques font partie d'une nouvelle classe de détecteurs de courbure ayant les mêmes propriétés que α-synucléine. / Communication between membrane-bound organelles is mediated by vesicular trafficking, a process which requires continual membrane remodeling. Highly curved vesicles bud from a donor compartment through functioning of different coat protein complexes, and fuse with an acceptor compartment thanks to proteins of the membrane fusion machinery. The proteins involved in vesicle budding and fusion have been extensively studied. Recently, the discovery of membrane curvature sensors revealed that membrane trafficking could be regulated at an additional level, through detection of the shape of a membrane. The first membrane curvature sensor identified was the ALPS (Amphipathic Lipid Packing Sensor) motif, which has been found in a number of proteins that function in the early secretory pathway and nuclear envelope. One example is GMAP-210, a long coiled-coil tether localizing to cis-Golgi membranes, which has an ALPS motif at its extreme N-terminus. This ALPS motif was found to fold into an amphipathic helix and bind to small liposomes in vitro. However, the identity of the vesicles that this curvature sensor binds to in cells is not known. Another protein - α-synuclein - has also been reported to bind preferentially to highly curved membranes. This neuronal protein localizes to synaptic vesicles and is involved in maintaining the reserve pool of vesicles in pre-synaptic nerve terminals. α-Synuclein, known for its central role in the development of Parkinson’s disease, contains a region that is unstructured in solution, but forms an amphipathic helix upon binding to small liposomes in vitro. The chemistry and geometry of the amphipathic helices formed by ALPS motifs and α-synuclein are very different. The ALPS motif has a well-developed hydrophobic face but a poor polar side with few charged residues. α-Synuclein, in contrast, has a restrained hydrophobic side, and a zwitterionic polar face rich in charged residues. The main goal of the project was to compare the in vivo and in vitro membrane binding properties of these two amphipathic helices of opposite structure. When expressed in yeast cells, these two curvature sensors promoted the accumulation of vesicular structures possessing different characteristics. The N-terminus of GMAP-210 containing its ALPS motif (GMAPN) co-localized specifically with early secretory pathway markers, whereas a probe containing a portion of the amphipathic membrane-binding helix of α-synuclein co-localized with endocytic and post-Golgi markers. Mutagenesis of the ALPS motif and the inversion of the ALPS sequence in GMAPN support the conclusion that this membrane curvature sensor is targeted to specific vesicles in cells through direct protein-lipid, rather than protein-protein interactions. Our analysis has shown, remarkably, that mammalian curvature sensors expressed in yeast cells preserve their capacity to target specific vesicles, those of the early secretory pathway for ALPS motifs, and endocytic/post-Golgi vesicles for α-synuclein. The membrane composition of these vesicles corresponds to the preferred in vitro liposome binding properties of these membrane curvature sensors. The contrasting chemistries of ALPS motifs and α-synuclein are well adapted to each of these two major membrane environments in the cell. The HeliQuest algorithm is designed to search databases for membrane-binding amphipathic helices, including ALPS motifs. A new module designed to identify amphipathic helices with properties similar to α-synuclein has recently been developed. Searches of both yeast and human protein databases has identified candidate α-synuclein-like amphipathic helices in numerous proteins. We prepared a set of probes, in which these helices are displayed at the end of the GMAPN coiled-coil. An initial study of their co-localization in yeast cells with a set of organelle markers demonstrates specific localization patterns, suggesting that these helices may have specific membrane targeting capacities. Further work will explore the question of whether these amphipathic helices are part of a novel class of α-synuclein-like curvature sensors.

Os radionuclídeos naturais das séries radioativas do 238U, 235U e 232Th são frequentemente utilizados como traçadores em estudos ambientais para a compreensão da dinâmica que ocorre no ambiente marinho e terrestre, como por exemplo, em pesquisas de processos oceânicos e gerenciamento da região costeira. No ambiente marinho, estes radionuclídeos podem ser empregados para estimar fluxos biogeoquímicos de partículas e de nutrientes que ocorrem tanto na coluna dágua, quanto nos sedimentos. Várias pesquisas aplicam a distribuição e o respectivo desequilíbrio dos radionuclídeos naturais no meio ambiente, inclusive em modelos geocronológicos para se obter informações históricas em testemunhos sedimentares. Nesse estudo, realizou-se a caracterização radioquímica das distribuições de 226Ra, 228Ra e 210Pb de uma coluna sedimentar denominada 1B (248 cm de comprimento), coletada na Baía do Almirantado, Antártica. A metodologia utilizada incluiu a lixiviação ácida de amostras de sedimentos, seguida de separação radioquímica sequencial de 226Ra e de 228Ra pela co-precipitação com Ba(Ra)SO4 e de 210Pb pela co-precipitação com PbCrO4. Todas as medidas foram realizadas pela contagem alfa e beta total dos precipitados obtidos, em um detector proporcional de fluxo gasoso de baixa radiação de fundo. As concentrações de atividade de 226Ra e 210Pb foram empregadas para se estimar a atividade de 210Pbnão-suportado presentes no perfil sedimentar 1B. Considerando-se as concentrações de atividade de 210Pbnão-suportado obtidas e a aplicação do modelo CIC(Constant Initial Concentration), foi possível determinar a taxa de sedimentação de 0,59±0,05 cm/ ano. / The natural radionuclides from radioactive series of 238U, 235U and 232Th have been applied as tracers in environmental studies for understanding the dynamics that occur in both marine and terrestrial environment, as for example, in research of oceanic processes and management of the coastal region. In the marine environment, these radionuclides can be used to estimate biogeochemical fluxes of marine particles and nutrients that occur in the water column as well as in the sediment. Several research works applied the distribution and the respective disequilibrium degree of natural radionuclides in the environment, including geochronological models for obtaining historical information on samples of certain sediment profile. In this study we performed a radiochemical characterization of the distribution of 226Ra, 228Ra and 210Pb from a sedimentary column called 1B (248 cm long) collected in the Admiralty Bay, Antarctic Peninsula region. The methodology used included the acid leaching of sediment samples followed by the radiochemical sequential separation of 226Ra and 228Ra by co-precipitation with Ba(Ra)SO4 and 210Pb by co-precipitation with PbCrO4. All measurements were carried out by counting of gross alpha and gross beta measures in a low background gas flow proportional detector. The activity concentrations of 226Ra and 210Pb were used to estimate the unsupported 210Pb activities present in sediment profile 1 B. Based on unsupported 210Pb data and the application of the CIC model (Constant Initial Concentration), it was possible to determine the sedimentation rate of 0.59 ± 0.05 cm /year.

Os radionuclídeos naturais das séries radioativas do 238U, 235U e 232Th são frequentemente utilizados como traçadores em estudos ambientais para a compreensão da dinâmica que ocorre no ambiente marinho e terrestre, como por exemplo, em pesquisas de processos oceânicos e gerenciamento da região costeira. No ambiente marinho, estes radionuclídeos podem ser empregados para estimar fluxos biogeoquímicos de partículas e de nutrientes que ocorrem tanto na coluna dágua, quanto nos sedimentos. Várias pesquisas aplicam a distribuição e o respectivo desequilíbrio dos radionuclídeos naturais no meio ambiente, inclusive em modelos geocronológicos para se obter informações históricas em testemunhos sedimentares. Nesse estudo, realizou-se a caracterização radioquímica das distribuições de 226Ra, 228Ra e 210Pb de uma coluna sedimentar denominada 1B (248 cm de comprimento), coletada na Baía do Almirantado, Antártica. A metodologia utilizada incluiu a lixiviação ácida de amostras de sedimentos, seguida de separação radioquímica sequencial de 226Ra e de 228Ra pela co-precipitação com Ba(Ra)SO4 e de 210Pb pela co-precipitação com PbCrO4. Todas as medidas foram realizadas pela contagem alfa e beta total dos precipitados obtidos, em um detector proporcional de fluxo gasoso de baixa radiação de fundo. As concentrações de atividade de 226Ra e 210Pb foram empregadas para se estimar a atividade de 210Pbnão-suportado presentes no perfil sedimentar 1B. Considerando-se as concentrações de atividade de 210Pbnão-suportado obtidas e a aplicação do modelo CIC(Constant Initial Concentration), foi possível determinar a taxa de sedimentação de 0,59±0,05 cm/ ano. / The natural radionuclides from radioactive series of 238U, 235U and 232Th have been applied as tracers in environmental studies for understanding the dynamics that occur in both marine and terrestrial environment, as for example, in research of oceanic processes and management of the coastal region. In the marine environment, these radionuclides can be used to estimate biogeochemical fluxes of marine particles and nutrients that occur in the water column as well as in the sediment. Several research works applied the distribution and the respective disequilibrium degree of natural radionuclides in the environment, including geochronological models for obtaining historical information on samples of certain sediment profile. In this study we performed a radiochemical characterization of the distribution of 226Ra, 228Ra and 210Pb from a sedimentary column called 1B (248 cm long) collected in the Admiralty Bay, Antarctic Peninsula region. The methodology used included the acid leaching of sediment samples followed by the radiochemical sequential separation of 226Ra and 228Ra by co-precipitation with Ba(Ra)SO4 and 210Pb by co-precipitation with PbCrO4. All measurements were carried out by counting of gross alpha and gross beta measures in a low background gas flow proportional detector. The activity concentrations of 226Ra and 210Pb were used to estimate the unsupported 210Pb activities present in sediment profile 1 B. Based on unsupported 210Pb data and the application of the CIC model (Constant Initial Concentration), it was possible to determine the sedimentation rate of 0.59 ± 0.05 cm /year.

The presidential address introduces the 2018 conference theme through rhetorical, political, spiritual, and biblical understandings of fear as well as communicative and homiletical strategies for addressing fear in preaching. In addition to Aristotle’s Rhetoric, the prevalence of fear amid current U.S. political discourse is examined in light of the rhetorical analyses of Martha Nussbaum, professor of law and ethics at The University of Chicago. To develop an appropriately reverent fear of God while addressing the myriad anxieties around us, we may query our fears to better understand what is at stake in ignoring or addressing socio-political concerns. Beyond the rhetoric of fear, the spiritual writings of Julian of Norwich as well as numerous biblical texts (including the Book of Job and Jesus’ Sermon on the Mount) suggest communicative strategies that invite a homiletical poesis of divine love and compassion, including musical and theopoetic expressions of faith.

This keynote address was delivered on August 6, 2018 at Societas Homiletica at Duke University in Durham, North Carolina and explores the relationship between preaching and identity. The lecture introduces Pauli Murray, a local saint whose activism, writings, and ministry challenged the church and broader society. After a detailed introduction, I consider three principal influences on Pauli’s voice: Cornelia Smith Fitzgerald, Langston Hughes, and James H. Cone. Cornelia Smith Fitzgerald, Pauli’s maternal grandmother, provided a lens for thinking about the ethical and spatial contexts in which sermons arise. Langston Hughes, a fêted poet and author, offered literary inspiration and a model for moving among different genres. James Cone, a path-breaking scholar, gave Pauli vital theological footing and a framework for linking preaching, identity, and activism. Overall, I argue that Pauli Murray makes a singular contribution to the study of African American preaching.