Rapid responses of high-mountain vegetation to early Holocene environmental changes in the Swiss Alps

1 The Early Holocene sediment of a lake at tree line (Gouillé Rion, 2343 m a.s.l.) in the Swiss Central Alps was sampled for plant macrofossils. Thin (0.5 cm) slices, representing time intervals of c. 50 years each from 11 800 to 7800 cal. year bp, were analysed and the data compared with independent palaeoclimatic proxies to study vegetational responses to environmental change. 2 Alpine plant communities (e.g. with Salix herbacea) were established at 11 600–11 500 cal. year bp, when oxygen-isotope records showed that temperatures increased by c. 3–4 °C within decades. Larix decidua trees reached the site at c. 11 350 cal. year bp, probably in response to further warming by 1–2 °C. Forests dominated by L. decidua persisted until 9600 cal. year bp, when Pinus cembra became more important. 3 The dominance of Larix decidua for two millennia is explained by dry summer conditions, and possibly low winter temperatures, which favoured it over the late-successional Pinus cembra. Environmental conditions were a result of variations in the earth's orbit, leading to a maximum of summer and a minimum of winter solar radiation. Other heliophilous and drought-adapted species, such as Dryas octopetala and Juniperus nana, could persist in the open L. decidua forests, but were out-competed when the shade-tolerant P. cembra expanded. 4 The relative importance of Larix decidua decreased during periods of diminished solar radiation at 11 100, 10 100 and 9400 cal. year bp. Stable concentrations of L. decidua indicate that these percentage oscillations were caused by temporary increases of Pinus cembra, Dryas octopetala and Juniperus nana that can be explained by increases in moisture and/or decreases in summer temperature. 5 The final collapse of Larix decidua at 8400 cal. year bp was possibly related to abrupt climatic cooling as a consequence of a large meltwater input to the North Atlantic. Similarly, the temporary exclusion of Pinus cembra from tree line at 10 600–10 200 cal. year bp may be related to slowing down of thermohaline circulation at 10 700–10 300 cal. year bp. 6 Our results show that tree line vegetation was in dynamic equilibrium with climate, even during periods of extraordinarily rapid climatic change. They also imply that forecasted global warming may trigger rapid upslope movements of the tree line of up to 800 m within a few decades or centuries at most, probably inducing large-scale displacements of plant species as well as irrecoverable biodiversity losses.

Cheek Tooth Extraction Via a Minimally Invasive Transbuccal Approach and Intradental Screw Placement in 54 Equids

OBJECTIVE: To describe (1) preoperative findings and surgical technique, (2) intraoperative difficulties, and (3) postoperative complications and long-term outcome of equine cheek tooth extraction using a minimally invasive transbuccal screw extraction (MITSE) technique. STUDY DESIGN: Retrospective case series. ANIMALS: Fifty-four equids; 50 horses, 3 ponies, and 1 mule. METHODS: Fifty-eight MITSE procedures were performed to extract cheek teeth in 54 equids. Peri- and intraoperative difficulties, as well as short- (<1 month) and long-term (>6 months) postoperative complications were recorded. Followup information was obtained through telephone interviews, making specific inquiries about nasal discharge, facial asymmetry, and findings consistent with surgical site infection. RESULTS: Preoperative findings that prompted exodontia included 50 cheek teeth with apical infections, 48 fractures, 4 neoplasia, 2 displacements, and 1 supernumerary tooth. Previous oral extraction was attempted but had failed in 55/58 (95%) animals because of cheek tooth fracture in 28, or insufficient clinical crown for extraction with forceps in 27. MITSE was successful in removing the entire targeted dental structure in 47/58 (81%) procedures. However, MITSE failed to remove the entire targeted dental structure in 11/58 (19%) procedures and was followed by repulsion in 10/11 (91%). Short-term postoperative complications included bleeding (4/58 procedures, 7%) and transient facial nerve paralysis (4/58 procedures, 7%). Owners were satisfied with the functional and cosmetic outcome for 40/41 (98%) animals with followup. CONCLUSION: MITSE offers an alternate for cheek tooth extraction in equids, where conventional oral extraction is not possible or has failed. Overall, there was low morbidity, which compares favorably with invasive buccotomy or repulsion techniques

Periazetabuläre Frakturen bei Hüftprothesen

Periazetabuläre Frakturen bei Hüftprothesen nehmen aufgrund der Überalterung und der zunehmenden Aktivität alter Menschen zu. Die periprothetischen Azetabulumfrakturen werden anhand der Einteilung von Letournel klassifiziert. Wenn beide Azetabulumpfeiler bei Hüftprothese betroffen sind, wird auch von einer Beckendiskontinuität gesprochen. Durch eine laterale Kompression können auch periazetabuläre Schambeinastfrakturen und/oder transiliakale Frakturen auftreten. Für die Therapieentscheidung (konservativ, alleinige Osteosynthese, Revisionshüfttotalprothese mit oder ohne zusätzliche Osteosynthese des Vorder- und/oder Hinterpfeilers) und die Zugangswahl bei operativer Versorgung werden patientenspezifische (Alter, Morbidität, Osteoporose, Aktivitätslevel des Patienten), frakturspezifische (Frakturtyp, Dislokationsausmaß, Impression des Doms oder der Hinterwand) und auch prothesenspezifische Faktoren (Art der implantierten Prothese [Hemiprothese vs. Totalprothese], Pfannenstabilität, Zeichen eines Prothesenabriebs, Ausmaß und Lokalisation einer azetabulären Lyse, Stabilität und Lysezeichen des Prothesenschafts) berücksichtigt. Bei akuten Beckendiskontinuitäten werden neben einer Osteosynthese des dorsalen Pfeilers zunehmend eine schnell ossär integrierbare Pfanne (Tantalum [„Trabecular Metal“: TM]) mit oder ohne Augment und/oder Allograft und allenfalls in einer sog. „Cup-Cage“-Technik (TM-Pfanne mit einem abstützenden Revisionsring [Burch-Schneider-Ring] analog zur Therapie von chronischen Beckendiskontinuitäten empfohlen. Bei großen Lysezonen und starken Dislokationen des vorderen Pfeilers und der quadrilateralen Fläche können intrapelvine Zugänge (modifizierter Stoppa- oder Pararectus-Zugang nach Keel) zur zusätzlichen Zuggurtungsosteosynthese des vorderen Pfeilers und Abstützung der quadrilateralen Fläche gewählt werden.

Search for satellites near comet 67P/Churyumov-Gerasimenko using Rosetta/OSIRIS images

Context. The European Space Agency Rosetta mission reached and started escorting its main target, the Jupiter-family comet 67P/Churyumov-Gerasimenko, at the beginning of August 2014. Within the context of solar system small bodies, satellite searches from approaching spacecraft were extensively used in the past to study the nature of the visited bodies and their collisional environment. Aims. During the approaching phase to the comet in July 2014, the OSIRIS instrument onboard Rosetta performed a campaign aimed at detecting objects in the vicinity of the comet nucleus and at measuring these objects' possible bound orbits. In addition to the scientific purpose, the search also focused on spacecraft security to avoid hazardous material in the comet's environment. Methods. Images in the red spectral domain were acquired with the OSIRIS Narrow Angle Camera, when the spacecraft was at a distance between 5785 km and 5463 km to the comet, following an observational strategy tailored to maximize the scientific outcome. From the acquired images, sources were extracted and displayed to search for plausible displacements of all sources from image to image. After stars were identified, the remaining sources were thoroughly analyzed. To place constraints on the expected displacements of a potential satellite, we performed Monte Carlo simulations on the apparent motion of potential satellites within the Hill sphere. Results. We found no unambiguous detections of objects larger than similar to 6 m within similar to 20 km and larger than similar to 1 m between similar to 20 km and similar to 110 km from the nucleus, using images with an exposure time of 0.14 s and 1.36 s, respectively. Our conclusions are consistent with independent works on dust grains in the comet coma and on boulders counting on the nucleus surface. Moreover, our analysis shows that the comet outburst detected at the end of April 2014 was not strong enough to eject large objects and to place them into a stable orbit around the nucleus. Our findings underline that it is highly unlikely that large objects survive for a long time around cometary nuclei.

Two distinct filopodia populations at the growth cone allow to sense nanotopographical extracellular matrix cues to guide neurite outgrowth

BACKGROUND The process of neurite outgrowth is the initial step in producing the neuronal processes that wire the brain. Current models about neurite outgrowth have been derived from classic two-dimensional (2D) cell culture systems, which do not recapitulate the topographical cues that are present in the extracellular matrix (ECM) in vivo. Here, we explore how ECM nanotopography influences neurite outgrowth. METHODOLOGY/PRINCIPAL FINDINGS We show that, when the ECM protein laminin is presented on a line pattern with nanometric size features, it leads to orientation of neurite outgrowth along the line pattern. This is also coupled with a robust increase in neurite length. The sensing mechanism that allows neurite orientation occurs through a highly stereotypical growth cone behavior involving two filopodia populations. Non-aligned filopodia on the distal part of the growth cone scan the pattern in a lateral back and forth motion and are highly unstable. Filopodia at the growth cone tip align with the line substrate, are stabilized by an F-actin rich cytoskeleton and enable steady neurite extension. This stabilization event most likely occurs by integration of signals emanating from non-aligned and aligned filopodia which sense different extent of adhesion surface on the line pattern. In contrast, on the 2D substrate only unstable filopodia are observed at the growth cone, leading to frequent neurite collapse events and less efficient outgrowth. CONCLUSIONS/SIGNIFICANCE We propose that a constant crosstalk between both filopodia populations allows stochastic sensing of nanotopographical ECM cues, leading to oriented and steady neurite outgrowth. Our work provides insight in how neuronal growth cones can sense geometric ECM cues. This has not been accessible previously using routine 2D culture systems.

Stand Structure Governs the Crown Collisions of Lodgepole Pine

We investigated tree sway and crown collision behavior of even-aged lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) stands of different structure in Alberta, Canada, to examine how these factors might affect loss of leaf area as stands mature. The Two Creeks stand (TC) had high density and slender trees, while the Chickadee stand (CH) had stout trees. The TC stand was then thinned (TCT) to reduce the stand density. For each stand, simultaneous tree sways of a group of 10 trees were monitored with biaxial clinometers during wind speed of 5 m/s (canopy top). Crown collisions were reconstructed by combining sway displacement of individual trees with their respective crown dimensions. Comparing the sway statistics between stands with contrasting mean bole slenderness (TC and CH) indicated that more slender trees have greater sway displacements, faster sway speeds, and a greater depth of collision. Disturbance by thinning increased sway displacements, sway speeds, and depth of collisions at TCT. Tree sway patterns were circular in shape and not aligned with wind direction, but patterns were elongated after thinning. This demonstrates the high frequency of crown collision experienced by stands with slender trees and supports the notion that crown collisions result in empty space between crowns of trees.

Sedimentology, magnetics and chemistry on palaeolake core D100 from the Gobi Desert

The Gaxun Nur Basin in arid China is tectonically influenced by the left-lateral displacements along the Gobi-Altay and Qilian Shan shear zones, resulting in a large pull-apart basin with strong subsidence in the interior. The up to 300 m thick basin fills consist of fluvio-lacustrine fine-grained deposits mainly transported by river discharges from the Tibetan Plateau. They led to a large depositional area of more than 28,000 qkm in size with presently dry terminal lakes at the outer edges. This vast area serves as a main source for loess transport to south-eastern regions of China (Loess Plateau) caused by the variable winter monsoon. Based on geochemical and sedimentological analyses of the sediment core D100 retrieved from a deep drilling in the centre of the Gaxun Nur Basin following questions have to be answered: 1. Reconstruction of the water balance and determination of hydrological cycles during interglacial and glacial periods. 2. Reconstructing variations in lacustrine environment and aeolian activities with respect to transitional phases fro, warm to cold stages (MIS 4 to 5 and older stages). 3. Establishing a sustainable chronology for the last 250 ka.

El tercer espacio: cruce de culturas en la literatura de frontera

Favorecida por el proyecto económico y político de la globalización, es posible observar cómo, desde las últimas décadas del pasado siglo, se ha ido agudizando una tendencia a la hibridación que, si bien podríamos considerar casi innata de la condición humana, ha trascendido en nuestros días la mera enunciación retórica hasta llegar a impregnar casi todos los estratos de la cultura. En el campo de los estudios literarios este proceso de mixturación ha contribuido a generar una verdadera explosión de la llamada literatura de frontera, caracterizada no sólo por una mutación en las mentalidades de los sectores sociales y étnicos -desde los que se origina-, sino por profundos cambios en las mismas estructuras sociales, culturales y lingüísticas. Esta problemática pone en cuestión la homogeneidad y la esencialidad de la identidad cultural, pues es un fenómeno actual que nos remite, inevitablemente, a la complejidad de la identidad. Precisamente, podríamos hablar de deslizamientos que se van produciendo en los diferentes planos de las manifestaciones artísticas, tendiendo éstos a amalgamarse, a fundirse uno con otros, en un cruzamiento de líneas de fuga, de rupturas, que atraviesan ese nuevo espacio, el Tercer Espacio, donde los diferentes discursos se van hibridando unos con otros, rompiendo la imagen de unidad, la imagen unitaria y tradicional. Unidad que no existió nunca y que no puede existir de ningún modo, porque es una imagen acotada que se esfuma en el caótico tejido de lo vivo, en la conformación y evolución de la raza humana.

Trazo de un encuentro : los límites de la teoría frente a la práctica política en la lectura althusseriana de Maquiavelo

La producción teórica de Louis Althusser forja una alianza entre materialismo y política que asedia los espacios comunes de la tradición teórica marxista. Para Althusser, las posibilidades de actualizar la teoría, de transformarla en una herramienta útil para el análisis y la formulación de estrategias acordes a los problemas planteados por la coyuntura, implica un trabajo sobre los conceptos tal como se encontraban en la teoría marxista clásica. En la crisis manifiesta del movimiento comunista internacional se expresa el correlato entre impotencia teórica y fracaso político. Por esta razón, y aun considerando los cambios de acento que se registran a lo largo de sus escritos, su discurso insiste en señalar los bloqueos e insuficiencias conceptuales de la teoría, los “límites absolutos" que anidan en la adherencia idealista de parte de las formulaciones de Marx. En los límites que traza sobre la teoría marxista y llevando la alianza entre materialismo y política más allá de Marx, Althusser encuentra a Maquiavelo. Nos proponemos indagar cómo este rodeo permite a Althusser replantear, no sin desplazamientos, la relación entre teoría y práctica política, en el horizonte de volver a la primera permeable a los matices que la coyuntura imprime sobre la segunda.

Temperature and salinity reconstruction for sediment core GeoB3313-1

We reconstructed changes of temperature, salinity, and productivity within the southern Peru-Chile Current during the last 8000 years from a high-resolution sediment core recovered at 41°S using alkenones, isotope ratios of planktic foraminifera, biogenic opal, and organic carbon. Paleotemperatures and paleosalinities reached maximum values at ~5500 years ago and thereafter declined to modern values, whereas paleoproductivity continuously increased throughout the last 8000 years. We ascribe these long-term Holocene trends primarily to latitudinal shifts of the Antarctic Circumpolar Current (ACC). The concurrence with shifts in the position of the Southern Westerlies points to a common response of atmospheric and oceanographic circulation patterns off southern Chile. Millennial- to centennial-scale fluctuations of paleotemperatures and paleosalinities, on the other hand, lag displacements in the position of the Southern Westerlies but reveal a significant correlation to short-term temperature changes in Antarctica, indicating a high-latitude control of the ACC at these timescales.

Partir e ficar : Dinâmicas nos processos de migraçao e imigraçao no norte de Minas Gerais- Brasil

This proposal assumes that the migration process is a socio-spatial process. Where desires, goals, fears and hopes of migrating become identities, social constructs that ultimately lead to ways of belonging. Place is a form of interaction, whether between man and the environment, or the man with a specific space. Place demand belonging. Belonging demand identity. Migration then became a strategy, a resistance, an eternal possibility or impossibility of staying or leaving. The displacements eventually cause changes in the relationships and interactions of individuals in their most different spaces. In this sense, they grasp the shifting process of an individual or social group, it is seen that migration and immigration is a process beyond "of being in different social spaces", is a mode of social reproduction defined in relations of time and space, emphasizing the duality of being in motion. Therefore, this proposal seeks to emphasize the dynamics of migration and immigration process in their contexts, as well as highlight the economic social constructions arising from these proceedings, in its social, cultural, political and, thus characterizing the various identities of individuals

Imágenes de la edición border y sudaca : El entre-catálogos de Eloísa Cartonera

Este artículo analiza un corpus literario en el cual se construyen ciertas imágenes de la edición "border" y "sudaca" de Eloísa Cartonera. Las autobiografías de editores de proyectos editoriales independientes, alternativos y autogestivos discuten modos de organización y asociación en el marco de la transnacionalización editorial. La temporalidad inscrita en estas imágenes permite observar las tensiones, movimientos, desplazamientos, estabilizaciones y cristalizaciones que se producen en sus instancias de organización, afiliación y desafiliación.

Los sentidos del (sin) trabajo. Subjetividad y demanda en el movimiento de trabajadores desocupados en Argentina

Este artículo recupera resultados de una investigación sobre la subjetividad colectiva involucrada en el movimiento de desocupados en Argentina. En particular, se analizan los sentidos colectivos involucrados en la construcción de la demanda (de "trabajo") que elabora el movimiento de desocupados. En este plano, se reconstruyen los sentidos históricos del trabajo articulados en el discurso de los participantes en el movimiento, investigando los desplazamientos y las condensaciones semánticas que hacen de "trabajo" un significante denso. La articulación de los sentidos del trabajo en la subjetividad subalterna es una clave para comprender el fenómeno de movilización social, debido a su potencialidad para significar una situación social (el desempleo) como un daño y un referente para la organización y la acción colectiva.

Un tratado sobre la extranjería de lo propio (El uruguayo de Copi)

El uruguayo de Copi es un tratado sobre la lengua, una descripción desopilante de un país, un ácido comentario político, una burla impiadosa de los valores culturales, una pesadilla personal, un golpe de teatro donde cualquier versión de la realidad se vuelve precaria y se trastoca al compás de una imaginación afiebrada que no hace más que dar rienda suelta a los materiales del inconsciente. Pero sobre todo, es la visión desnuda de la relación imposible de un escritor con el país que ha dejado atrás. Un tratado sobre el horror de confrontarse con la realidad carcelaria del pasado. Un intento de "calmar" los fantasmas, es decir, de hacerlos hablar y moverse y morir y resucitar en una trama que transita en medio de cadáveres y mares desaparecidos y un territorio que se achica constantemente. Un texto fundamental para indagar cuestiones relacionadas con la "identidad" nacional y con las maneras en que los desplazamientos culturales (con su concomitante tránsito entre lenguas y visiones del mundo), tan comunes en el mundo actual, afectan la escritura.

San Luis : Del empleo industrial al refugio estatal : Cambios y desplazamientos en la estructura ocupacional

A partir de la implementación de las leyes de promoción industrial, en la Provincia de San Luis se configuró una estructura sectorial del empleo con características particulares respecto de la del resto del país. En efecto, hasta la década de 1990, el sector secundario de la economía concentraba aproximadamente el 50 de los ocupados. Sin embargo, desde 1991 este escenario se modifica y aumentan los ocupados en el sector terciario de la economía. La pérdida de peso de la industria como generadora de empleo no fue compensada por un incremento de otros sectores productivos: las ramas que muestran un comportamiento expansivo son Servicios y Sector Público. Como resultado de estos desplazamientos, se modificaron también la estructura de las ocupaciones y las calificaciones requeridas: quienes se habían capacitado laboralmente trabajando en la industria se encuentran hoy en un escenario en el cual sus calificaciones han perdido valor en un mercado que ahora demanda distintos saberes y capacidades. Frente a esto, el empleo estatal y las ocupaciones de baja calificación en el sector Servicios configuran un refugio, una alternativa a la desocupación. Este trabajo analiza los cambios, rupturas y continuidades en la estructura ocupacional de la Provincia de San Luis a partir de datos provenientes de los Censos Nacionales de Población y Vivienda y de la Encuesta Permanente de Hogares