The Little Ice Age in Scientific Perspective: Cold Spells and Caveats

Contrary to the position taken by Kelly and Ó Gráda, a rich body of regional- to large-scale temperature reconstructions that span from the last millennium to almost the entire Holocene confirms the existence of several temperature depressions that occurred at different intensities and spatial ranges between c. 1350 and 1900, thus supporting the conception of a Little Ice Age. Nonetheless, the genuine uncertainties that continue to surround paleoclimatic study suggest that methodologies and findings are subject to further refinement.

Complexity and non-linearity in earth surface processes - concepts, methods and applications

Complexity has long been recognized and is increasingly becoming mainstream in geomorphology. However, the relative novelty of various concepts and techniques associated to it means that ambiguity continues to surround complexity. In this commentary, we present and discuss a variety of recent contributions that have the potential to help clarify issues and advance the use of complexity in geomorphology.

Triple isotope (δD, δ17O, δ18O) study on precipitation, drip water and speleothem fluid inclusions for a Western Central European cave (NW Switzerland)

Deuterium (δD) and oxygen (δ18O) isotopes are powerful tracers of the hydrological cycle and have been extensively used for paleoclimate reconstructions as they can provide information on past precipitation, temperature and atmospheric circulation. More recently, the use of δ17O excess derived from precise measurement of δ17O and δ18O gives new and additional insights in tracing the hydrological cycle whereas uncertainties surround this proxy. However, 17O excess could provide additional information on the atmospheric conditions at the moisture source as well as about fractionations associated with transport and site processes. In this paper we trace water stable isotopes (δD,δ17O and δ18O) along their path from precipitation to cave drip water and finally to speleothem fluid inclusions for Milandre cave in northwestern Switzerland. A two year-long daily resolved precipitation isotope record close to the cave site is compared to collected cave drip water (3 months average resolution) and fluid inclusions of modern and Holocene stalagmites. Amount weighted mean δD,δ18O and δ17O are -71.0‰, -9.9‰, -5.2‰ for precipitation, -60.3‰, -8.7‰, -4.6‰ for cave drip water and -61.3‰, -8.3‰, -4.7‰ for recent fluid inclusions respectively. Second order parameters have also been derived in precipitation and drip water and present similar values with 18 per meg for 17O excess whereas d-excess is 1.5‰ more negative in drip water. Furthermore, the atmospheric signal is shifted towards enriched values in the drip water and fluid inclusions (Δ of ~ + 10‰ for δD). The isotopic composition of cave drip water exhibits a weak seasonal signal which is shifted by around 8 - 10 months (groundwater residence time) when compared to the precipitation. Moreover, we carried out the first δ17O measurement in speleothem fluid inclusions, as well as the first comparison of the δ17 O behaviour from the meteoric water to the fluid inclusions entrapment in speleothems. This study on precipitation, drip water and fluid inclusions will be used as a speleothem proxy calibration for Milandre cave in order to reconstruct paleotemperatures and moisture source variations for Western Central Europe.

tRNA-derived fragments target the small ribosomal subunit to fine-tune translation

Post-transcriptional cleavage of RNA molecules to generate smaller fragments is a widespread mechanism that enlarges the structural and functional complexity of cellular RNomes. In particular, fragments deriving from both precursor and mature tRNAs represent one of the rapidly growing classes of post-transcriptional RNA pieces. Importantly, these tRNA-derived fragments (tRFs) possess distinct expression patterns, abundance, cellular localizations, or biological roles compared with their parental tRNA molecules [1]. Here we present evidence that tRFs from the archaeon Haloferax volcanii directly bind to ribosomes. In a previous genomic screen for ribosome-associated small RNAs we have identified a 26 residue long fragment originating from the 5’ part of valine tRNA (Val-tRF) to be by far the most abundant tRF in H. volcanii [2]. The Val-tRF is processed in a stress- dependent manner and was found to primarily target the small ribosomal subunit in vitro and in vivo. Translational activity was markedly reduced in the presence of Val-tRF, while control RNA fragments of similar length did not show inhibition of protein biosynthesis. Crosslinking experiments and subsequent primer extension analyses revealed the Val-tRF interaction site to surround the mRNA path in the 30S subunit. In support of this, binding experiments demonstrated that Val-tRF does compete with mRNAs for ribosome binding. Therefore this tRF represents a ribosome-bound non-protein-coding RNA (ncRNA) capable of regulating gene expression in H. volcanii under environmental stress conditions probably by fine-tuning the rate of protein production [1].

tRNA-derived fragments target the small ribosomal subunit to fine-tune translation

Post-transcriptional cleavage of RNA molecules to generate smaller fragments is a widespread mechanism that enlarges the structural and functional complexity of cellular RNomes. In particular, fragments deriving from both precursor and mature tRNAs represent one of the rapidly growing classes of post-transcriptional RNA pieces. Importantly, these tRNA-derived fragments (tRFs) possess distinct expression patterns, abundance, cellular localizations, or biological roles compared with their parental tRNA molecules [1]. Here we present evidence that tRFs from the archaeon Haloferax volcanii directly bind to ribosomes. In a previous genomic screen for ribosome-associated small RNAs we have identified a 26 residue long fragment originating from the 5’ part of valine tRNA (Val-tRF) to be by far the most abundant tRF in H. volcanii [2]. The Val-tRF is processed in a stress- dependent manner and was found to primarily target the small ribosomal subunit in vitro and in vivo. Translational activity was markedly reduced in the presence of Val-tRF, while control RNA fragments of similar length did not show inhibition of protein biosynthesis. Crosslinking experiments and subsequent primer extension analyses revealed the Val-tRF interaction site to surround the mRNA path in the 30S subunit. In support of this, binding experiments demonstrated that Val-tRF does compete with mRNAs for ribosome binding. Therefore this tRF represents a ribosome-associated non-protein-coding RNA (rancRNA) capable of regulating gene expression in H. volcanii under environmental stress conditions probably by fine-tuning the rate of protein production [3].

tRNA-derived fragments target the small ribosomal subunit to fine-tune translation

Post-transcriptional cleavage of RNA molecules to generate smaller fragments is a widespread mechanism that enlarges the structural and functional complexity of cellular RNomes. In particular, fragments deriving from both precursor and mature tRNAs represent one of the rapidly growing classes of post-transcriptional RNA pieces. Importantly, these tRNA-derived fragments (tRFs) possess distinct expression patterns, abundance, cellular localizations, or biological roles compared with their parental tRNA molecules [1]. Here we present evidence that tRFs from the halophilic archaeon Haloferax volcanii directly bind to ribosomes. In a previous genomic screen for ribosome-associated small RNAs we have identified a 26 residue long fragment originating from the 5’ part of valine tRNA (Val-tRF) to be by far the most abundant tRF in H. volcanii [2]. The Val-tRF is processed in a stress-dependent manner and was found to primarily target the small ribosomal subunit in vitro and in vivo. Translational activity was markedly reduced in the presence of Val-tRF, while control RNA fragments of similar length did not show inhibition of protein biosynthesis. Crosslinking experiments and subsequent primer extension analyses revealed the Val-tRF interaction site to surround the mRNA path in the 30S subunit. In support of this, binding experiments demonstrated that Val-tRF does compete with mRNAs for ribosome binding. Therefore this tRF represents a ribosome-associated non-coding RNA (rancRNA) capable of regulating gene expression in H. volcanii under environmental stress conditions probably by fine-tuning the rate of protein production [3].

Disease risk factors and humoral antibody response to periodontal-associated pathogens: A model to evaluate periodontal disease in older adults

Periodontal diseases (PD) are infectious, inflammatory, and tissue destructive events which affect the periodontal ligament that surround and support the teeth. Periodontal diseases are the major cause of tooth loss after age 35, with gingivitis and periodontitis affecting 75% of the adult population. A select group of bacterial organisms are associated with periodontal pathogenesis. There is a direct association between oral hygiene and prevention of PD. The importance of genetic differences and host immune response capabilities in determining host, susceptibility or resistance to PD has not been established. This study examined the risk factors and serum (humoral) immune response to periodontal diseased-associated pathogens in a 55 to 80+ year old South Texas study sample with PD. This study sample was described by: age, sex, ethnicity, the socioeconomic factors marital status, income and occupation, IgG, IgA, IgM immunoglobulin status, and the autoimmune response markers rheumatoid factor (RF) and antinuclear antibody (ANA). These variables were used to determine the risk factors associated with development of PD. Serum IgG, IgA, IgM antibodies to bacterial antigens provided evidence for disease exposure.^ A causal model for PD was constructed from associations for risk factors (ethnicity, marital status, income, and occupation) with dental exam and periodontitis. The multiple correlation between PD and ethnicity, income and dental exam was significant. Hispanics of low income were least likely to have had a dental exam in the last year and most likely to have PD. The etiologic agents for PD, as evidenced by elevated humoral antibody responses, were the Gram negative microorganisms Bacteroides gingivalis, serotypes FDC381 and SUNYaBA7A1-28, and Wolinella recta. Recommendation for a PD prevention and control program are provided. ^

The effects of ethnicity and ethnic composition of schools on physical activity and nutrition behaviors of 8th and 11th graders in Texas

With rates of obesity and overweight continuing to increase in the US, the attention of public health researchers has focused on nutrition and physical activity behaviors. However, attempts to explain the disparate rates of obesity and overweight between whites and Hispanics have often proven inadequate. Indeed, the nebulous term ‘ethnicity’ provides little important detail in addressing potential biological, behavioral, and environmental factors that may affect rates of obesity and overweight. In response to this, the present research seeks to test the explanatory powers of ethnicity by situating the nutrition and physical activity behaviors of whites and Hispanic into their broader social contexts. It is hypothesized that a student's gender and grade level, as well as the socioeconomic status and ethnic composition of their school, will have more predictive power for these behaviors than will self-reported ethnicity. ^ Analyses revealed that while ethnicity did not seem to impact nutrition behaviors among the wealthier schools and those with fewer Hispanics, ethnicity was relevant in explaining these behaviors in the poorest tertile of schools and those with the highest number of Hispanics. With respect to physical activity behaviors, the results were mixed. The variables representing regular physical activity, participation in extracurricular physical activities, and performance of strengthening and toning exercises were more likely to be determined by SES and ethnic composition than ethnicity, especially among 8th grade males. However, school sports team and physical education participation continued to vary by ethnicity, even after controlling for SES and ethnic composition of schools. In conclusion then, it is important to understand the intersecting demographic and social variables that define and surround the individual in order to understand nutrition and physical activity behaviors and thus overweight and obesity.^

Grain size distribution in surface sediments samples of the continental shelf and slope of southeast Greenland

During "Meteor" Cruise 6/1966 in the northwest Atlantic a systematic survey of the bottom topography of the southeast Greenland continental margin was undertaken. Eighty-seven profiles transverse to the shelf edge at distances of 3-4 nautical miles and two longitudinal profiles parallel to the coast were carried out with the ELAC Narrow Beam Echo-Sounder giving a reliable record of even steep slopes. On the basis of the echo soundings the topography and morphology of the continental shelf and slope are evaluated. A detailed bathymetric chart and a serial profile chart were designed as working material for the morphological research. These maps along with the original echograms are morphometrically evaluated. The analysis of the sea bottom features is the basis of a subsequent morphogenetical interpretation, verified and extended by means of interpretation of magnetic data and sediment analysis (grain size, roundness, lithology). The results of the research are expressed in a geomorphological map. The primary findings can be summarized as follows: 1) The southeast Greenland shelf by its bottom topography can be clearly designated as a glacially formed area. The glacial features of the shelf can be classified into two zones nearly parallel to the coast: glacial erosion forms on the inner shelf and glacial accumulation forms on the outer shelf. The inner shelf is characterized by the rugged and hummocky topography of ice scoured plains with clear west/east slope asymmetry. On the outer shelf three types of glacial accumulation forms can be recognized: ice margin deposits with clearly expressed terminal moraines, glacial till plains and glaciomarine outwash fans. Both zones of the shelf can be subdivided into two levels of relief. The ice scoured plains, with average depths of 240 meters (m), are dissected to a maximum depth of 1060 m (Gyldenloves Trough) by trough valleys, which are the prolongations of the Greenland fjords. The banks of the outer shelf, with an average depth of 180 m, surround glacial basins with a maximum depth of 670 meters. 2) The sediments of the continental shelf can be classified as glacial due to their grain size distribution and the degree of roundness of the gravel particles. The ice margin deposits on the outer shelf can be recognized by their high percentage of gravels. On the inner shelf a rock surface is suggested, intermittently covered by glacial deposits. In the shelf troughs fine-grained sediments occur mixed with gravels. 3) Topography and sediments show that the southeast Greenland shelf was covered by an ice sheet resting on the sea floor during the Pleistocene ice-age. The large end moraines along the shelf edge probably indicate the maximum extent of the Wurm shelf ice resting on the sea floor. The breakthroughs of the end moraines in front of the glacial basins suggest that the shelf ice has floated further seaward over the increasing depths. 4) Petrographically the shelf sediments consist of gneisses, granites and basalts. While gneisses and granites occire on the nearby coast, basalt is not known to exist here. Either this material has been drifted by icebergs from the basalt province to the north or exists on the southeast Greenland shelf itself. The last interpretation is supported bythe high portion of basalt contained in the sediment samples taken and the strong magnetic anomalies probably caused by basaltic intrusions. 5) A magnetic profile allows the recognition of two magnetically differing areas which approximately coincide with the glacial erosion and accumulation zones. The inner shelf shows a strong and variable magnetic field because the glacially eroded basement forms the sea floor. The outer shelf is characterized by a weak and homogenous magnetic field, as the magnetized basement lies at greater depthy, buried by a thick cover of glacial sediments. The strong magnetic anomalies of the inner shelf are probably caused by dike swarms, similar to those observed further to the north in the Kangerdlugssuaq Fjord region. This interpretation is supported by the high basalt content of the sediment samples and the rough topography of the ice scoured plains which correlates in general with the magnetic fluctuations. The dike structures of the basement have been differentially eroded by the shelf ice. 6) The continental slope, extending from the shelf break at 313 m to a depth of 1270 m with an average slope of 11°, is characterized by delta-shaped projections in front of the shelf basins, by marginal plateaus, ridges and hills, by canyons and slumping features. The projections could be identified as glaciomarine sediment fans. This conclusion is supported by the strong decrease of magnetic field intensity. The deep sea hills and ridges with their greater magnetic intensities have to be regarded as basement outcrops projecting through the glaciomarine sediment cover. The upper continental rise, sloping seaward at about 2°, is composed of wide sediment fans and slump material. A marginal depression on the continental rise running parallel to the shelf edge has been identified. In this depression bottom currents capable of erosion have been recorded. South of Cape Farvel the depression extends to the accumulation zone of the "Eirik" sedimentary ridge. 7) By means of a study of the recent marine processes, postglacial modification of the ice-formed relief can be postulated. The retention effect of the fjord troughs and the high velocity of the East Greenland stream prevents the glacial features from being buried by sediments. Bottom currents capable of active erosion have only been found in the marginal depression on the continental rise. In addition, at the time of the lowest glacio-eustatic sea level, the shelf bottom was not situated in the zone of wave erosion. Only on the continental slope and rise bottom currents, sediment slumps and turbidity currents have led to significant recent modifications. Considering these results, the geomorphological development of the southeast Greenland continental terrace can be suggested as follows: 1. initial formation of a "peneplain", 2. fluvial incision, 3. submergence, and finally 4. glacial modification.

Juan José Saer – Ricardo Suspisiche: cruce de lenguajes para la creación de un espacio

Una experiencia vivida y comentada por el propio Suspisiche -pintor del litoral santafecino- y la frecuentación de los textos saerianos abren la posibilidad de este trabajo que pretende un acercamiento al cruce de lenguajes entre las obras de ambos. Cada uno desde su propia estética genera un espacio que trasciende la referencialidad para convertirse en una poética, pero también en una verdadera cosmovisión. Las obras de Saer van develando su concepción de la literatura y del mundo, concepción según la cual la realidad es huidiza, imposible de aprehender. Esta certeza conduce su proceso de escritura. aporta sus tópicos recurrentes que no son más que la insistencia desesperada por comunicar las propias percepciones. De la pintura de Suspisiche, dijo el crítico Taverna Irigoyen: "es un paisaje que pareciera entregársele fácilmente, y cuando lo va a hacer suyo, a penetrarlo, se convierte en un espejismo inatrapable". ¿Cómo resuelven ambos. en la superficie textual. esa desconfianza en la posibilidad de instaurar sus universos? Por el camino del lenguaje, por la experimentación con que pueden transformar, superponer, reiterar, hasta crear un significado. Nuestro trabajo trata de demostrar cómo ambos evolucionan hacia la esencialidad que se logra por la progresiva supresión de lo accesorio, el abandono del pintoresquismo y una praxis que exige técnicas cada vez más rigurosas. Para el/o ese analiza el proceso de productividad de esos espacios que envuelven el trayecto vital del hombre y son uno con él, no por afinidades psicologistas. a la manera romántica, sino fatalmente, por impregnación. por simbiosis, por acoplamiento. No es el hombre el que se apropia del paisaje. es el espacio el que lo contiene. y permite al artista. desde adentro. una mirada que no es sólo recreación estética. sino ideología. en el sentido de visión del mundo.

¡Me engañaste, me mentiste! La embajada persa a Atenas (Ar. Ach. 61-124) y sus implicaturas frente al público

Atendiendo a la relación establecida entre la comedia y los ámbitos político- legales que la circundan, se ha podido instituir un vínculo entre la ficción cómica y la realidad política de la Atenas clásica que se percibe fundamentalmente en las primeras comedias de Aristófanes. Dentro de Acarnienses podremos entonces determinar un nuevo punto de análisis si consideramos que en las breves declamaciones del persa se cifra uno de los recursos más notorios de la diplomacia estatal: la manipulación ante la asamblea del discurso de los embajadores de una nación por parte de la voz autorizada de la pólis receptora (Ammendola: 2001-2002). Será nuestro propósito abordar un costado diverso de esta escena definiendo su peso específico, aparentemente secundario, en la trama total de la obra. De ese modo nos interesará detectar la verdadera trascendencia del comportamiento del embajador persa respecto de los ciudadanos atenienses representados en la persona del viejo Diceópolis

Violencia de género : Descripción y resultados de una investigación sobre mujeres golpeadas

La Cátedra "Fundamentos, Técnicas e Instrumentos de la Exploración Psicológica II" inició en el año 2006 una Investigación titulada: Violencia: Mujer golpeada. Delimitación de estructura psíquica mediante Técnicas Proyectivas. El rastreo bibliográfico nos permitió delimitar dos líneas explicativas que giran alrededor de esta situación, a saber: a) Una correspondiente a la línea psico - socio - económica. b) La otra centrada psicoanalíticamente sobre la estructura y dinámica psíquica de las mujeres que son golpeadas (deslindando las situaciones extremas de la perversión y las que corresponden a las costumbres de tipo cultural). La primera línea no satisface nuestras expectativas, ya que nos dan razones suficientes, pero no necesarias. Se asientan en lo que hemos dado en llamar "Teoría de la escasez" (falta de recursos, de afectos y de red social), pero sabemos que no es necesario que estas "faltas" se encuentren presentes para que una mujer sea golpeada. La segunda línea explicativa en cambio, nos permitió hipotetizar que "algo de la estructura psíquica debía estar en juego." Esto nos llevó a implementar una Batería de Técnicas Proyectivas para investigar estructuras psíquicas, la cual aplicamos a un grupo de casos obtenido de población urbana, de distintas edades, clases sociales y nivel educacional. Obteniendo hasta el momento indicadores que nos hablan de una indefensión yoica. Prevaleciendo las defensas maníacas reveladas como idealización del otro, negación e identificación con el agresor

Violencia de género : Descripción y resultados de una investigación sobre mujeres golpeadas

La Cátedra "Fundamentos, Técnicas e Instrumentos de la Exploración Psicológica II" inició en el año 2006 una Investigación titulada: Violencia: Mujer golpeada. Delimitación de estructura psíquica mediante Técnicas Proyectivas. El rastreo bibliográfico nos permitió delimitar dos líneas explicativas que giran alrededor de esta situación, a saber: a) Una correspondiente a la línea psico - socio - económica. b) La otra centrada psicoanalíticamente sobre la estructura y dinámica psíquica de las mujeres que son golpeadas (deslindando las situaciones extremas de la perversión y las que corresponden a las costumbres de tipo cultural). La primera línea no satisface nuestras expectativas, ya que nos dan razones suficientes, pero no necesarias. Se asientan en lo que hemos dado en llamar "Teoría de la escasez" (falta de recursos, de afectos y de red social), pero sabemos que no es necesario que estas "faltas" se encuentren presentes para que una mujer sea golpeada. La segunda línea explicativa en cambio, nos permitió hipotetizar que "algo de la estructura psíquica debía estar en juego." Esto nos llevó a implementar una Batería de Técnicas Proyectivas para investigar estructuras psíquicas, la cual aplicamos a un grupo de casos obtenido de población urbana, de distintas edades, clases sociales y nivel educacional. Obteniendo hasta el momento indicadores que nos hablan de una indefensión yoica. Prevaleciendo las defensas maníacas reveladas como idealización del otro, negación e identificación con el agresor

¡Me engañaste, me mentiste! La embajada persa a Atenas (Ar. Ach. 61-124) y sus implicaturas frente al público

Atendiendo a la relación establecida entre la comedia y los ámbitos político- legales que la circundan, se ha podido instituir un vínculo entre la ficción cómica y la realidad política de la Atenas clásica que se percibe fundamentalmente en las primeras comedias de Aristófanes. Dentro de Acarnienses podremos entonces determinar un nuevo punto de análisis si consideramos que en las breves declamaciones del persa se cifra uno de los recursos más notorios de la diplomacia estatal: la manipulación ante la asamblea del discurso de los embajadores de una nación por parte de la voz autorizada de la pólis receptora (Ammendola: 2001-2002). Será nuestro propósito abordar un costado diverso de esta escena definiendo su peso específico, aparentemente secundario, en la trama total de la obra. De ese modo nos interesará detectar la verdadera trascendencia del comportamiento del embajador persa respecto de los ciudadanos atenienses representados en la persona del viejo Diceópolis

¡Me engañaste, me mentiste! La embajada persa a Atenas (Ar. Ach. 61-124) y sus implicaturas frente al público

Atendiendo a la relación establecida entre la comedia y los ámbitos político- legales que la circundan, se ha podido instituir un vínculo entre la ficción cómica y la realidad política de la Atenas clásica que se percibe fundamentalmente en las primeras comedias de Aristófanes. Dentro de Acarnienses podremos entonces determinar un nuevo punto de análisis si consideramos que en las breves declamaciones del persa se cifra uno de los recursos más notorios de la diplomacia estatal: la manipulación ante la asamblea del discurso de los embajadores de una nación por parte de la voz autorizada de la pólis receptora (Ammendola: 2001-2002). Será nuestro propósito abordar un costado diverso de esta escena definiendo su peso específico, aparentemente secundario, en la trama total de la obra. De ese modo nos interesará detectar la verdadera trascendencia del comportamiento del embajador persa respecto de los ciudadanos atenienses representados en la persona del viejo Diceópolis