Plant clonal morphologies and spatial patterns as self-organized responses to resource-limited environments

We propose here to interpret and model peculiar plant morphologies (cushions, tussocks) observed in the Andean altiplano as localized structures. Such structures resulting in a patchy, aperiodic aspect of the vegetation cover are hypothesized to self-organize thanks to the interplay between facilitation and competition processes occurring at the scale of basic plant components biologically referred to as 'ramets'. (Ramets are often of clonal origin.) To verify this interpretation, we applied a simple, fairly generic model (one integro-differential equation) emphasizing via Gaussian kernels non-local facilitative and competitive feedbacks of the vegetation biomass density on its own dynamics. We show that under realistic assumptions and parameter values relating to ramet scale, the model can reproduce some macroscopic features of the observed systems of patches and predict values for the inter-patch distance that match the distances encountered in the reference area (Sajama National Park in Bolivia). Prediction of the model can be confronted in the future to data on vegetation patterns along environmental gradients as to anticipate the possible effect of global change on those vegetation systems experiencing constraining environmental conditions.Comment: 14 pages, 6figure

Comunidades vegetales de los bofedales de la Cordillera Real (Bolivia) bajo el calentamiento global

Los humedales altoandinos (bofedales) son uno de los más amenazados frente al calentamiento global. Dada la estrecha relación entre bofedales y agua, el retroceso glacial podrá causar su contracción. Con tres proxis del cambio climático (área de bofedales, influencia glaciar y altitud) se infirió indirectamente cómo éstos pueden afectar a las comunidades vegetales. Las hipótesis fueron 1) que la reducción del área del bofedal podría afectar negativamente la diversidad de plantas - la influencia glaciar y la altitud podrían afectar ésta relación por su efectos en la heterogeneidad ambiental y la diversidad – y 2) que el retroceso glacial puede afectar indirectamente la diversidad a través de cambios en las especies dominantes. Se midió la diversidad α y β aditiva de plantas en 20 bofedales (>4.400 m) de la Cordillera Real (Bolivia). Se encontraron 63 especies (riqueza especifica: 5-22/cuadrante 1m²). Variaciones del área e influencia glacial no se relacionaron con cambios en la vegetación, pero la diversidad fue menor a mayor altitud. Las hojas de Oxychloe andina son más resistentes al estrés ambiental por su mayor masa foliar seca, a diferencia de Distichia spp., indicando que los bofedales dominados por O. andina son más secos. Además tienen más especies que también se pueden encontrar en las laderas. Mientras, las comunidades de Distichia spp. son menos tolerantes al déficit hídrico. Si el retroceso glacial reducirá el agua en las próximas décadas, el bofedal de O. andina podrá ser más abundante a expensas de los de Distichia spp., generando desafíos para la conservación. Oxychloe andina , Retroceso glacial

Facilitation among plants in alpine environments in the face of climate change

While there is a large consensus that plant–plant interactions are a crucial component of the response of plant communities to the effects of climate change, available data remain scarce, particularly in alpine systems. This represents an important obstacle to making consistent predictions about the future of plant communities. Here, we review current knowledge on the effects of climate change on facilitation among alpine plant communities and propose directions for future research. In established alpine communities, while warming seemingly generates a net facilitation release, earlier snowmelt may increase facilitation. Some nurse plants are able to buffer microenvironmental changes in the long term and may ensure the persistence of other alpine plants through local migration events. For communities migrating to higher elevations, facilitation should play an important role in their reorganization because of the harsher environmental conditions. In particular, the absence of efficient nurse plants might slow down upward migration, possibly generating chains of extinction. Facilitation-climate change relationships are expected to shift along latitudinal gradients because (1) the magnitude of warming is predicted to vary along these gradients, and (2) alpine environments are significantly different at low vs. high latitudes. Data on these expected patterns are preliminary and thus need to be tested with further studies on facilitation among plants in alpine environments that have thus far not been considered. From a methodological standpoint, future studies will benefit from the spatial representation of the microclimatic environment of plants to predict their response to climate change. Moreover, the acquisition of long-term data on the dynamics of plant-plant interactions, either through permanent plots or chronosequences of glacial recession, may represent powerful approaches to clarify the relationship between plant interactions and climate change

Genre et Acces au Foncier : Etude Comparative des Modes d’Acquisition de la Terre chez les Femmes du Sud et du Nord de la Cote d’Ivoire : Cas d’Akoupé et Becouéfin ; Nahoualakaha et Torgokaha

La présente étude s’est intéressée à la question du mode d’accès à la terre par les femmes du Nord, et celles Sud de la Côte d’Ivoire. Elle se propose de comparer les déterminants socioculturels de l’accessibilité différentiée à la terre chez les femmes Sénoufo et Akyé. La population ciblée pour l’étude menée entre Avril 2021 et Juin 2021 est constituée d’autorités coutumières, des leaders communautaires et des femmes résidentes ou non, et membres ou non des coopératives agricoles. La démarche sur laquelle s’est appuyée cette étude est de type qualitatif orientée selon la méthode comparative et conduite à l’aide d’entretien individuel, de focus groups et d’observation participante. La théorie comparative a été convoquée pour mieux faire la comparaison entre ces deux entités (femme du Nord et femme du Sud) et apporter un meilleur éclairage sur la question de leur accès à la terre. L’analyse de la question de l’accessibilité de la terre a montré que les femmes du Sud de la Côte d’Ivoire accèdent de plus en plus à la terre car les normes, règles et valeurs de cette société ont connu des mutations tendant à intégrer la femme dans le partage de la terre même si cela ne se fait pas de façon équitable entre l’homme et la femme. Chez les femmes du Nord de la Côte d’Ivoire, l’accès définitif à la terre est quasiment impossible à cause de la rigidité des valeurs, normes et règles qui régulent cette société.   This study looked at the question of how women in the north and south of Côte d'Ivoire access land. It compares the socio-cultural determinants of differential access to land among Senoufo and Akye women. The target population is made up of the customary authorities, community leaders, and women who may or may not be residents or members of agricultural cooperatives. The study was conducted from April to June. The approach of this study was qualitative and comparative, using individual interviews, focus groups and participant observation. The comparative theory was used to better compare these two entities (women from the North and women from the South) and to shed more light on the issue of their access to land. The analysis of the issue of access to land showed that women in the south of Côte d'Ivoire are gaining access to land because the norms, rules and values of this society have changed to include women in the sharing of land, even if this is not done in an equitable manner between men and women. Among women in the north of Côte d'Ivoire, definitive access to land is almost impossible because of the rigidity of the values, norms and rules that regulate this society

Métodos para estudiar el efecto del cambio climático sobre los bofedales y sus servicios ambientales inherentes

A pesar que las montañas tropicales son uno de los biomas más amenazados del mundo, es escasa la investigación fundamental y aplicada sobre los efectos de los cambios globales en la biodiversidad y los beneficios de los ecosistemas. Las zonas húmedas de los ambientes altoandinos tropicales - los bofedales - son espacios verdes dentro de una matriz árida que concentran una rica biodiversidad y variedad de beneficios asociados (almacenamiento de carbono, regulación de agua y producción de ganado), de los que dependen millones de personas. Estos frágiles ecosistemas están amenazados por la rapidez del derretimiento de los glaciares de los cuales dependen significativamente. El proyecto BIOTHAW - Biodiversidad e interacciones de uso de los suelos frente a la evolución de la disponibilidad de agua de los glaciares en las zonas húmedas de los Andes tropicales - tiene por objetivo desarrollar un marco de modelización para establecer escenarios de biodiversidad y uso de las tierras en un contexto de cambios globales. El enfoque del proyecto integra tres componentes: 1) la modificación de los aportes de agua glaciares a las zonas húmedas, 2) la biodiversidad (animal y vegetal) de estas zonas y 3) las prácticas de cultivo (patrones de utilización de las tierras, dinámica de las estructuras de la ganadería). Nutridos por escenarios climáticos y socioeconómicos, los diferentes modelos combinados con mapas de distribución de las zonas húmedas permitirán establecer escenarios de la biodiversidad y los servicios de los bofedales, con el fin de definir zonas prioritarias de conservación. (résumé d'auteur

Les restes humains archéologiques en France : entre objets de science et sujets de droit

International audienceOver the past 40 years, the increase in the number of archaeological excavations of large funeral complexes in France has led to a considerable increase in the number of human remains in the State’s excavation sites. These remains are not strictly speaking part of the archaeological material but are instead considered “scientific documentation”. On the one hand, the requirements of science necessitate the mobilization of all available techniques in order to better understand the populations that have left us these traces. On the other hand, material and cultural limitations necessarily lead to sampling techniques being seen as an efficient archaeological system. On the other hand, the mission of general interest that is archaeological research requires particular care be taken with these remains, sparing them from an overly managerial and short-term vision. The ethical virtues of archaeological excellence must not be forgotten; archaeological knowledge must be based on the requirement of scientific rigour. This primary requirement is questioned in particular by the choices made in the management of human remains collections. A second ethical requirement leads to questions about the legal or moral limits of the first. Should scientific rigour be limited in certain cases, particularly when the research involves human remains? Should remains be subject to a specific legal or ethical status that would distinguish them from other elements of archaeological material? This article addresses these questions through the prism of the study of the case of the perfectly preserved body of Louise de Quengo, a 17th century Breton noble discovered in 2014 in Rennes (France).Depuis 40 ans, la multiplication des fouilles archéologiques de grands ensembles funéraires en France a entrainé un accroissement considérable des vestiges osseux humains dans les dépôts de fouilles de l'État. Ces restes ne font pas partie du mobilier archéologique stricto-sensu mais relèvent de la « documentation scientifique ». D'un côté, les exigences de la science commandent de mobiliser toutes les techniques disponibles afin de mieux connaître les populations qui nous ont laissé ces traces. De l'autre côté, des limites matérielles et culturelles conduiraient à voir dans les techniques d'échantillonnage un dispositif archéologique efficient. La mission d'intérêt général qu'est la recherche archéologique commande au contraire de porter un soin particulier à ces vestiges en les épargnant d'une vision trop gestionnaire et de court terme. Les vertus éthiques de l'excellence archéologique ne doivent pas être oubliées, ainsi le savoir archéologique doit-il d'abord porter une exigence de rigueur scientifique. Cette exigence première est notamment questionnée par les choix de gestion des collections des restes humains. Une seconde exigence éthique conduit à s'interroger sur les limites juridiques ou morales de la première. L'ambition de rigueur scientifique doit-elle être limitée dans certaines hypothèses, notamment lorsque la recherche porte sur des restes humains? Ces restes doivent-ils faire l'objet d'un statut juridique ou éthique spécifique qui tendrait à les distinguer des autres éléments du mobilier archéologique? L'article se propose d'aborder ces questions sous le prisme de l'étude du cas du corps parfaitement bien conservé de Louise de Quengo, noble bretonne du XVIIe découverte en 2014 à Rennes (France). Over the past 40 years, the increase in the number of archaeological excavations of large funeral complexes in France has led to a considerable increase in the number of human remains in the State's excavation sites. These remains are not strictly speaking part of the archaeological material but are instead considered "scientific documentation". On the one hand, the requirements of science necessitate the mobilization of all available techniques in order to better understand the populations that have left us these traces. On the other hand, material and cultural limitations necessarily lead to sampling techniques being seen as an efficient archaeological system. On the other hand, the mission of general interest that is archaeological research requires particular care be taken with these remains, sparing them from an overly managerial and short-term vision. The ethical virtues of archaeological excellence must not be forgotten; archaeological knowledge must be based on the requirement of scientific rigour. This primary requirement is questioned in particular by the choices made in the management of human remains collections. A second ethical requirement leads to questions about the legal or moral limits of the first. Should scientific rigour be limited in certain cases, particularly when the research involves human remains? Should remains be subject to a specific legal or ethical status that would distinguish them from other elements of archaeological material? This article addresses these questions through the prism of the study of the case of the perfectly preserved body of Louise de Quengo, a 17th century Breton noble discovered in 2014 in Rennes (France). Mots-clés Keywords corps humain, éthique, mobilier archéologique, collection anthropologique, échantillonnage, droit français, intérêt général archéologique human body, ethics, archaeological material, anthropological collection, sampling, French law, archaeological general interest Cet article est issu d'une communication présentée lors du colloque « Archéo-Éthique », accessible en français et en anglais

Field and current induced magnetization reversal in patterned Pseudo Spin Valve devices

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2007.Includes bibliographical references.The field and current induced magnetization switchings of Pseudo-Spin-Valve (PSV) devices are described in this dissertation. An aligned sequence of three (one optical and two electron-beam) lithographies was used to define the devices and their electrical contacts. The PSV stack comprised a layer of soft ferromagnetic material Ni80oFe20 (NiFe or Py), a non-magnetic spacer layer of Cu, a hard ferromagnetic layer of Co and a capping layer of Au. The current flowed in plane (CIP) and the devices displayed giant magnetoresistance (GMR). Three different shapes were investigated: notched bars, elliptical rings and rhomboidal rings. In the bars, the notches provided strong pinning potential wells for transverse domain walls in the NiFe layer, which, upon cycling an external field, reversed in a step-like fashion, with domain walls nucleating from both ends of the bars, due to strong magnetostatic coupling between both magnetic layers. Additional important magnetostatic coupling effects were measured and micromagnetic simulations confirmed the ubiquity of such coupling. Current induced magnetic switching (CIMS) experiments were conducted, and threshold densities of the order of 1011 A/m2 were used to switch the magnetization under an external bias field, and the critical current decreased with increasing bias.(cont.) Simulations showed that the Oersted field generated by the current was sufficiently strong to switch the magnetization in the soft NiFe layer, without taking into account spin-transfer torque effects. Ring shaped devices allowed for a diversity of responses depending on the contact configurations used which may be divided into two categories: the classical configurations and the Wheatstone bridge configurations. The latter allowed for large effective GMR ratios up to 200 %, with low switching fields down to a few Oersted. Both types of contact configuration along with micromagnetic simulations enabled a deep understanding of the field-induced reversal of both elliptical and rhomboidal rings. Magnetostatic coupling effects were also found to play a key role. CIMS experiments were conducted, and the rhomboidal ring device successfully switched, in the Wheatstone bridge configuration, under zero bias with a threshold current density of the order of 1011 A/m2. The density and length of current pulses was found to change the critical current density, which suggested that the spin structure of the domain walls in the NiFe layer was modified by the current.by Irénée A. Colin.S.M

Conversational Data Exploration: A Game-Changer for Designing Data Science Pipelines

This paper proposes a conversational approach implemented by the system Chatin for driving an intuitive data exploration experience. Our work aims to unlock the full potential of data analytics and artificial intelligence with a new generation of data science solutions. Chatin is a cutting-edge tool that democratises access to AI-driven solutions, empowering non-technical users from various disciplines to explore data and extract knowledge from it