Eocene sedimentary calcium carbonate contents and stable isotope composition of benthic foraminifera

'Hyperthermals' are intervals of rapid, pronounced global warming known from six episodes within the Palaeocene and Eocene epochs (~65-34 million years (Myr) ago) (Zachos et al., 2005, doi:10.1126/science.1109004; 2008, doi:10.1038/nature06588; Roehl et al., 2007, doi:10.1029/2007GC001784; Thomas et al., 2000; Cramer et al., 2003, doi:10.1029/2003PA000909; Lourens et al., 2005, doi:10.1038/nature03814; Petrizzo, 2005, doi:10.2973/odp.proc.sr.198.102.2005; Sexton et al., 2006, doi:10.1029/2005PA001253; Westerhold et al., 2007, doi:10.1029/2006PA001322; Edgar et al., 2007, doi:10.1038/nature06053; Nicolo et al., 2007, doi:10.1130/G23648A.1; Quillévéré et al., 2008, doi:10.1016/j.epsl.2007.10.040; Stap et al., 2010, doi:10.1130/G30777.1). The most extreme hyperthermal was the 170 thousand year (kyr) interval (Roehl et al., 2007) of 5-7 °C global warming (Zachos et al., 2008) during the Palaeocene-Eocene Thermal Maximum (PETM, 56 Myr ago). The PETM is widely attributed to massive release of greenhouse gases from buried sedimentary carbon reservoirs (Zachos et al., 2005; 2008; Lourenbs et al., 2005; Nicolo et al., 2007; Dickens et al., 1995, doi:10.1029/95PA02087; Dickens, 2000; 2003, doi:10.1016/S0012-821X(03)00325-X; Panchuk et al., 2008, doi:10.1130/G24474A.1) and other, comparatively modest, hyperthermals have also been linked to the release of sedimentary carbon (Zachos et al., 2008, Lourens et al., 2005; Nicolo et al., 2007; Dickens, 2003; Panchuk et al., 2003). Here we show, using new 2.4-Myr-long Eocene deep ocean records, that the comparatively modest hyperthermals are much more numerous than previously documented, paced by the eccentricity of Earth's orbit and have shorter durations (~40 kyr) and more rapid recovery phases than the PETM. These findings point to the operation of fundamentally different forcing and feedback mechanisms than for the PETM, involving redistribution of carbon among Earth's readily exchangeable surface reservoirs rather than carbon exhumation from, and subsequent burial back into, the sedimentary reservoir. Specifically, we interpret our records to indicate repeated, large-scale releases of dissolved organic carbon (at least 1,600 gigatonnes) from the ocean by ventilation (strengthened oxidation) of the ocean interior. The rapid recovery of the carbon cycle following each Eocene hyperthermal strongly suggests that carbon was resequestered by the ocean, rather than the much slower process of silicate rock weathering proposed for the PETM (Zachos et al., 2005; 2003). Our findings suggest that these pronounced climate warming events were driven not by repeated releases of carbon from buried sedimentary sources (Zachos et al., 2008, Lourens et al., 2005; Nicolo et al., 2007; Dickens, 2003; Panchuk et al., 2003) but, rather, by patterns of surficial carbon redistribution familiar from younger intervals of Earth history.

Diversidad étnica e identidad en la llanura costera del istmo oaxaqueño

En este artículo se desarrollan una serie puntos para entender al istmo oaxaqueño como una zona de convergencia cultural diversa, múltiple y por lo tanto diferenciada tanto en el ámbito de la historia de los pueblos que en ella viven, como en el ámbito de la estructura económica que permite su reproducción no sólo como grupos étnicos, sino como comunidades. El autor plantea que las manifestaciones culturales de cada grupo se confunden, se entrelazan se influencian mutuamente y en una lógica asociada a la perdurabilidad de dichos procesos, terminan por imponerse. Para comprender las relaciones interétnicas no basta con dar cuenta de las características generales de estos grupos sino que es necesario actualizar la información que se ha obtenido de ellos, sobre todo ahora que nuevos procesos nacionales o internacionales están afectando de manera irreversible la composición y la estructura de estas culturas. Aspectos como la falta de vías de comercialización de productos agrícolas y pesqueros, la marginación sempiterna, la falta de empleo a escala regional, la migración, etc.. son entre otros, las aristas de una realidad que se revela en su irremediable avance frente a comunidades que ponen en funcionamiento estrategias de reproducción y de sobreviviencia para mantenerse como comunidad. Las manifestaciones de las relaciones interétnicas aquí se definen como asimétricas horizontales en virtud de una diferenciación entre etnias y las relaciones entre ellas, de tal forma que así como se ha analizado la relación grupos étnicos-sociedad nacional, en la que se constatan desigualdades flagrantes a nivel del acceso a la riqueza generada en el país, calidad de vida, educación, comunicación, y otras variables importantes, de la misma manera se constata que en los grupos étnicos hay unos que tienen una posición privilegiada en el acceso a vías de comunicación, redes comerciales e influencia política, entre otros aspectos, mientras que otros se encuentran excluidos de ellos, no sólo por su condición de indígenas, sino también como consecuencia de la dominación entre etnias que existe en la región. Finalmente, el autor enfatiza que en esta zona del estado de Oaxaca existe una gama considerable de recursos naturales cuya apropiación y explotación para beneficios económicos está en el centro de la discusión actual. En efecto, el sistema de lagunas del Golfo de Tehuantepec, las reservas de la biodiversidad como la selva de los Chimalapas, o la actividad ganadera agrícola en la zona mixe son, entre otras, no sólo zonas importantes de explotación económica, que han fortalecido a grupos de poder locales. También son espacios de control estratégico para el futuro desarrollo del país pues en el istmo oaxaqueño se ha ubicado una fuente importante de riqueza en agua, bosques, especies endémicas, etc... que puede tener un papel importante en la vida económica regional y nacional. La cuestión es saber qué dispositivos sociales o legales se han puesto en marcha para definir a los beneficiarios de esa riqueza natural.

La estructura del himno ambrosiano y su relación con las funciones tonales de la escala musical

La utilización del himno religioso en Occidente, como una forma de control ideológico frente al avance de las heterodoxias, fue instaurada definitivamente por Ambrosio, obispo de Milán, al conciliar el material himnódico precedente con las necesidades catequísticas que la época le impuso. El episcopus milanés logró concebir un modelo poético, estrófico y rítmico de fácil recepción que funcionaba como instrumento de conversión e instrucción doctrinal y un regulador de las oraciones litúrgicas. El himno ambrosiano no fue, sin embargo, el primero que se ajustó a los principios del credo niceno en la lucha contra diversas formas de herejía, en particular el arrianismo, pero sí fue el primero que innovó desde lo musical y lo rítmico. Su popularidad, basada en su modo ?cantable?, se cimentó a partir de la novedad de su estructura compositiva, en la que se pueden advertir frecuentes correspondencias métricas y acentuales que posibilitaba una más rápida memorización. A través de esta comunicación se procurará exponer las innovaciones estructurales de la himnodia ambrosiana en materia rítmica, las cuales giran en torno a la repetición arbitraria del número ocho; asimismo el número ocho contiene funciones temático-emotivas comparables con las funciones tonales de la escala musical y, en especial, el modo jónico que es el que llegó hasta hoy como escala mayor natural

Career development and public policy

The rationale for policy interest in career development services, and the way in which this rationale is being strengthened by the current transformations in work and career, are discussed. The potential roles of public policy in relation to career development services are explored, along with ways in which such services can influence the policy-making process. A range of policy issues related to making career development services available to all throughout life are identified: these include the nature of such services, where they are to be located, and who is to pay for them. It is argued that there is a need for stronger structures and processes to bring together career development practitioners with policy- makers and other stakeholder interests in order to address tasks of common concern, at both national and international levels.

La educación media superior en México ante el reto de su universalización

En México, se legisló en octubre del 2011 la universalización de la educación media superior. En este contexto el artículo aborda los retos que presenta esta decisión desde la perspectiva de la oferta educativa en sus diferentes modalidades pero también los sentidos del bachillerato para los estudiantes, el nuevo público rural y los problemas de abandono escolar. Discute el tema de la diversificación necesaria y la desigualdad que la acompaña. Caracteriza la Reforma de la Educación Media Superior y la instauración del Sistema Nacional de Bachillerato desde un enfoque administrativo de la gestión y termina apuntando aspectos que habría que fortalecer desde una perspectiva pedagógica y de los sujetos. El escrito se sustenta por un lado en documentos oficiales y en datos del Instituto Nacional para la Evaluación de la Educación y por el otro en hallazgos de la línea de investigación cualitativa "Jóvenes y bachillerato"

La cooperación entre editores y bibliotecarios como estrategia institucional para la gestión de revistas científicas

El desarrollo sostenido de edición de revistas científicas ha abierto un campo de análisis y aplicación de conocimientos específicos para los bibliotecarios. El trabajo en cooperación con los editores enriquece a ambos actores pues, mientras los bibliotecarios conocen los estándares de normalización de la información y difusión del conocimiento científico, los editores se centran en las tareas académicas -pertinencia temática, relación con autores y evaluadores, revisión por pares. Los indicadores de evaluación de revistas científicas, tanto regionales como internacionales, se han afianzado en las últimas décadas a partir de acuerdos interinstitucionales y de la aceptación de los propios editores, aplicándose criterios de gestión y criterios formales de edición y evaluación. En este contexto, los editores necesitan un apoyo especializado que los acompañe en el proceso de desarrollo científico y técnico para conseguir que sus revistas se inserten en los principales núcleos de publicaciones científicas de cada disciplina. En este trabajo se presenta la experiencia de la Coordinación del Área de Publicaciones, en la Biblioteca de la Facultad de Humanidades y Ciencias de la Educación de la Universidad Nacional de La Plata, que edita actualmente más de 20 revistas

International governmental agencies and career guidance

The international Organization for Economic Cooperation and Develop-ment (OECD), like many national and international organizations concerned with economic development believes that career guidance has an important role in promoting the development of a country's human resources. (Mapping the future: Young People and career guidance OECD, 1996). Generally the economic development agencies always recommend that career guidance services should be strengthened. Too frequently, however, they do not recognize the difficulties facing counselor in the schools and do not give clear and specific recommendations, yet they appear to believe that the education or other au thorities who are responsible to guidance will quickly agree and provide more resources for guidance. In addition to economic development agencies, social and educational development agencies also make important recommendations concerning the provision of guidance services. UNESCO, for example, has published two re- cent reports (Policies and Guidelines for Educational and Vocational Guidelines for Equal Access and Opportunity for Girls and Women in Technical and Vocational Education.) It is interesting to compare the OECD and UNESCO rec- ommendations and note that the relative strengths of each set of recommenda- tions, and to imagine how they might be combined in advocating changes in policies and programs.

Cooperativa Agrícola Lucienville Ltda

A partir de la evolución del cooperativismo agrario argentino y a través de sus memorias y balances el presente estudio analiza el desenvolvimiento de la Cooperativa Agrícola Lucienville Ltda. durante el peronismo histórico. En esta etapa la institución adquiere particular incidencia en las diversas actividades económicas del agro regional (acopio de semillas, su industrialización y comercialización), al tiempo que refuerza su rol como centro de servicios sociales para los asociados.

La expansión territorial bonaerense, 1780-1880. Aportes de la historia local

El acceso a la propiedad legal de la tierra en la provincia de Buenos Aires es un tema de larga tradición en la historiografía argentina. Algunas de las primeras preguntas acerca del proceso de obtención de títulos sobre terrenos baldíos del estado durante el siglo XIX tuvieron respuestas en un marco general, explicaciones que se están profundizando y reforzando con estudios más focalizados espacialmente, de manera que la ocupación sin títulos tiene un lugar cada vez más importante en la historiografía. Sin duda estos avances deben mucho al crecimiento de los estudios locales desde mediados de la década de 1980, que ponen estas cuestiones en relación con el funcionamiento del mercado de factores y los aspectos socio-demográficos. Nos proponemos aquí realizar un estado de la cuestión acerca de este tema, dando cuenta de los avances realizados y las posibilidades que la historia local ofrece para desarrollar una nueva mirada sobre el mundo rural pampeano del siglo XIX

Sapropel cycles in the Mediterranean Sea

Water column stratification increased at climatic transitions from cold to warm periods during the late Quaternary and led to anoxic conditions and sapropel formation in the deep eastern Mediterranean basins. High-resolution data sets on sea-surface temperatures (SST) (estimated from UK'37 indices) and d18O of planktonic foraminifer calcite (d18Ofc) across late Pleistocene sapropel intervals show that d18Ofc decreased (between 1 and 4.6 per mil) and SST increased (between 0.7° and 6.7°C). Maximal d18Oseawater depletion of eastern Mediterranean surface waters at the transition is between 0.5 and 3.0 per mil, and in all but one case exceeded the depletion seen in a western Mediterranean core. The depletion in d18Oseawater is most pronounced at sapropel bases, in agreement with an initial sudden input of monsoon-derived freshwater. Most sapropels coincide with warming trends of SST. The density decrease by initial freshwater input and continued warming of the sea surface pooled fresh water in the surface layer and prohibited deep convection down to ageing deep water emplaced during cold and arid glacial conditions. An exception to this pattern is "glacial" sapropel S6; its largest d18Oseawater depletion (3 per mil) is almost matched by the depletion in the western Mediterranean Sea, and it is accompanied by surface water cooling following an initially rapid warming phase. A second period of significant isotopic depletion is in isotope stage 6 at the 150 kyr insolation maximum. While not expressed as a sapropel due to cold SST, it is in accord with a strengthened monsoon in the southern catchment.

Sable oxygen isotope and Mg/Ca ratios of planktonic foraminifera from DSDP Hole 31-292

This study presents new evidence of when and how the Western Pacific Warm Pool (WPWP) was established in its present form. We analyzed planktic foraminifera, oxygen isotopes, and Mg/Ca ratios in upper Miocene through Pleistocene sediments collected at Deep Sea Drilling Program (DSDP) Site 292. These data were then compared with those reported from Ocean Drilling Program (ODP) Site 806. Both drilling sites are located in the western Pacific Ocean. DSDP Site 292 is located in the northern margin of the modern WPWP and ODP Site 806 near the center of the WPWP. Three stages of development in surface-water conditions are identified in the region using planktic foraminferal data. During the initial stage, from 8.5 to 4.4 Ma, Site 806 was overlain by warm surface water but Site 292 was not, as indicated by the differences in faunal compositions and sea-surface temperature (SST) between the two sites. In addition, the vertical thermal gradient at Site 292 was weak during this period, as indicated by the small differences in the delta18O values between Globigerinoides sacculifer and Pulleniatina spp. During stage two, from 4.4 to 3.6 Ma, the SST at Site 292 rapidly increased to 27 °C, but the vertical thermal gradient had not yet be strengthened, as shown by Mg/Ca ratios and the presence of both mixed-layer dwellers and thermocline dwellers. Finally, a warm mixed layer with a high SST ca. 28 °C and a strong vertical thermal gradient were established at Site 292 by 3.6 Ma. This event is marked by the dominance of mixed-layer dwellers, a high and stable SST, and a larger differences in the delta18O values between G. sacculifer and Pulleniatina spp. Thus, evidence of surface-water evolution in the western Pacific suggests that Site 292 came under the influence of the WPWP at 3.6 Ma. The northward expansion of the WPWP from 4.4 to 3.6 Ma and the establishment of the modern WPWP by 3.6 Ma appear to be closely related to the closure of the Indonesian and Central American seaways.

Age determination and median grain size of sediment core EN31-PC2

Hemipelagic muds deposited during the past 5.3 cal kyr in the northern Gulf of Mexico (Orca Basin) contain seven intervals punctuated by relatively coarse siliciclastic grain-size peaks, planktonic faunal turnovers, and negative d13C excursions. We believe these episodes represent megaflood deposits reflecting historically unprecedented outfall of North American floodwater and terrigenous mud plumes into the gulf, resulting in collapse of the open-ocean pelagic ecosystem. The deposits record multidecadal episodes of high continental precipitation and large Mississippi River floods at ~4.7, 3.5, 3.0, 2.5, 2.0, 1.2, and 0.3 cal ka (500-1200-year recurrence interval). Variations in tropical plankton frequencies define submillenial warming intervals that culminate in these fluvial episodes. Strengthened tropical currents in the gulf at these times appear to have increased sea surface temperatures and associated flow of moist gulf air to the midwest. Terrestrial paleohydrologic records support the marine evidence for millennial-scale changes in recurrence of large midwest flood episodes.

Paleoclimatate of the Middle Burdigalian-Langhian period in Turkey

The Miocene is the last warm episode in Earth history, and this episode was well recorded in Turkey as shown by plant distribution and inferred numerical temperature values. In this study, Ören-Kultak, Hüssamlar and Karacaagac palynofloras from western Turkey, which are characterized by the thermophilous plants (Engelhardia, Sapotaceae, Cyrillaceae, Avicennia, Arecaceae, Palmae), are described. Age determinations of these palynofloras (middle Burdigalian-Langhian) are strengthened by the mammalian fossil record (MN4-5) and strontium isotope results. Palaeoclimate is humid and warm subtropical during the middle Burdigalian-Langhian time interval in Europe and Turkey. However, temperature difference has been observed between Europe and Turkey during this time interval and it could be explained by the palaeogeographic position of countries. Despite some discrepancies in the climatic values and palaeovegetation groups, warm climatic conditions are recorded, based on the palynofloras, in Turkey (Cayyrhan, Havza, Can, Etili, Gönen, Bigadic, Emet, Kirka and Kestelek, Sabuncubeli, Soma, Tire, Kulogullary, Bascayyr, Hüssamlar and Karacaagac), Greece and elsewhere in Europe throughout the middle Burdigalian-Langhian period. This warming is related to the Middle Miocene Climatic Optimum period. Carbon and oxygen isotope values obtained from tooth enamel of Gomphotherium sp. from Kultak and Hüssamlar indicate similar ecological condition during the Burdigalian-Langhian time. This isotopic result and high MAPDRY value from the Kultak locality are in agreement with ecological interpretation of mammalian fossils. Besides, according to the precipitation values, central and northwestern Anatolian sites provide more rainfall during the Burdigalian-Langhian time interval than the western Anatolian sites.

Probabilistic models for the prediction of a ship performance in dynamic ice

We introduce two probabilistic, data-driven models that predict a ship's speed and the situations where a ship is probable to get stuck in ice based on the joint effect of ice features such as the thickness and concentration of level ice, ice ridges, rafted ice, moreover ice compression is considered. To develop the models to datasets were utilized. First, the data from the Automatic Identification System about the performance of a selected ship was used. Second, a numerical ice model HELMI, developed in the Finnish Meteorological Institute, provided information about the ice field. The relations between the ice conditions and ship movements were established using Bayesian learning algorithms. The case study presented in this paper considers a single and unassisted trip of an ice-strengthened bulk carrier between two Finnish ports in the presence of challenging ice conditions, which varied in time and space. The obtained results show good prediction power of the models. This means, on average 80% for predicting the ship's speed within specified bins, and above 90% for predicting cases where a ship may get stuck in ice. We expect this new approach to facilitate the safe and effective route selection problem for ice-covered waters where the ship performance is reflected in the objective function.

Planktic foraminiferal abundance and stable oxygen isotope ratios of sediment cores from the Southern California Borderlands

A variety of evidence suggests that average sea surface temperatures (SSTs) during the last glacial maximum in the California Borderlands region were significantly colder than during the Holocene. Planktonic foraminiferal delta18O evidence and average SST estimates derived by the modern analog technique indicate that temperatures were 6°-10°C cooler during the last glacial relative to the present. The glacial plankton assemblage is dominated by the planktonic foraminifer Neogloboquadrina pachyderma (sinistral coiling) and the coccolith Coccolithus pelagicus, both of which are currently restricted to subpolar regions of the North Pacific. The glacial-interglacial average SST change determined in this study is considerably larger than the 2°C change estimated by Climate: Long-Range Investigation, Mapping, and Prediction (CLIMAP) [1981]. We propose that a strengthened California Current flow was associated with the advance of subpolar surface waters into the Borderlands region during the last glacial.