Reconstructions of eolian dust accumulation in northwest African margin sediments

Reconstructions of eolian dust accumulation in northwest African margin sediments provide important continuous records of past changes in atmospheric circulation and aridity in the region. Existing records indicate dramatic changes in North African dust emissions over the last 20 ka, but the limited spatial extent of these records and the lack of high-resolution flux data do not allow us to determine whether changes in dust deposition occurred with similar timing, magnitude and abruptness throughout northwest Africa. Here we present new records from a meridional transect of cores stretching from 31°N to 19°N along the northwest African margin. By combining grain size endmember modeling with 230Th-normalized fluxes for the first time, we are able to document spatial and temporal changes in dust deposition under the North African dust plume throughout the last 20 ka. Our results provide quantitative estimates of the magnitude of dust flux changes associated with Heinrich Stadial 1, the Younger Dryas, and the African Humid Period (AHP; ~11.7-5 ka), offering robust targets for model-based estimates of the climatic and biogeochemical impacts of past changes in North African dust emissions. Our data suggest that dust fluxes between 8 and 6 ka were a factor of ~5 lower than average fluxes during the last 2 ka. Using a simple model to estimate the effects of bioturbation on dust input signals, we find that our data are consistent with abrupt, synchronous changes in dust fluxes in all cores at the beginning and end of the AHP. The mean ages of these transitions are 11.8±0.2 ka (1Sigma) and 4.9±0.2 ka, respectively.

Trace elements in benthic foraminifera of sediment core V30-49

Eastern tropical Atlantic benthic foraminiferal Ba/Ca and Cd/Ca data from core V30-949 (3093 m) reveal large inferred changes in nutrient concentrations of deep Atlantic waters during the last 250 kyr. Relative changes in North Atlantic Deep Water contribution to this site are estimated by scaling the V30-49 Cd/Ca record to values of modern end-member water masses; these estimates agree well with the relative structure and timing of circulation changes in the eastern tropical Atlantic reconstructed from a d13C record-based mixing model (Raymo et al., 1997, doi:10.1029/97PA01019). Temporal differences between V30-49 Cd/Ca and Ba/Ca records suggest that the Ba/Ca record reflects changes in circulation with an additional increase in the Ba composition of deep Atlantic water masses during glacial episodes, possibly resulting from increased productivity. Similarity between the d13C and Ba/Ca records suggests that carbon isotopes in the deep glacial Atlantic also reflect productivity increases.

Stable isotope record, calcium carbonate conentrations, and sea surface temperture reconstructions of sediment cores from the North Atlantic

We analyze five high-resolution time series spanning the last 1.65 m.y.: benthic foraminiferal delta18O and delta13O, percent CaCO3, and estimated sea surface temperature (SST) at North Atlantic Deep Sea Drilling Project site 607 and percent CaCO3 at site 609. Each record is a multicore composite verified for continuity by splicing among multiple holes. These climatic indices portray changes in northern hemisphere ice sheet size and in North Atlantic surface and deep circulation. By tuning obliquity and precession components in the delta18O record to orbital variations, we have devised a time scale (TP607) for the entire Pleistocene that agrees in age with all K/Ar-dated magnetic reversals to within 1.5%. The Brunhes time scale is taken from Imbrie et al. [1984], except for differences near the stage 17/16 transition (0.70 to 0.64 Ma). All indicators show a similar evolution from the Matuyama to the Brunhes chrons: orbital eccentricity and precession responses increased in amplitude; those at orbital obliquity decreased. The change in dominance from obliquity to eccentricity occurred over several hundred thousand years, with fastest changes around 0.7 to 0.6 Ma. The coherent, in-phase responses of delta18O, delta13O, CaCO3 and SST at these rhythms indicate that northern hemisphere ice volume changes have controlled most of the North Atlantic surface-ocean and deep-ocean responses for the last 1.6 m.y. The delta13O, percent CaCO3, and SST records at site 607 also show prominent changes at low frequencies, including a prominent long-wavelength oscillation toward glacial conditions that is centered between 0.9 and 0.6 Ma. These changes appear to be associated neither with orbital forcing nor with changes in ice volume.

Enviromagnetic, major element, and grain-size analyses of surface sediment samples along the continental margin between East Brazil and Patagonia

Continental margin sediments of SE South America originate from various terrestrial sources, each conveying specific magnetic and element signatures. Here, we aim to identify the sources and transport characteristics of shelf and slope sediments deposited between East Brazil and Patagonia (20°-48°S) using enviromagnetic, major element, and grain-size data. A set of five source-indicative parameters (i.e., chi-fd%, ARM/IRM, S0.3T, SIRM/Fe and Fe/K) of 25 surface samples (16-1805 m water depth) was analyzed by fuzzy c-means clustering and non-linear mapping to depict and unmix sediment-province characteristics. This multivariate approach yields three regionally coherent sediment provinces with petrologically and climatically distinct source regions. The southernmost province is entirely restricted to the slope off the Argentinean Pampas and has been identified as relict Andean-sourced sands with coarse unaltered magnetite. The direct transport to the slope was enabled by Rio Colorado and Rio Negro meltwaters during glacial and deglacial phases of low sea level. The adjacent shelf province consists of coastal loessoidal sands (highest hematite and goethite proportions) delivered from the Argentinean Pampas by wave erosion and westerly winds. The northernmost province includes the Plata mudbelt and Rio Grande Cone. It contains tropically weathered clayey silts from the La Plata Drainage Basin with pronounced proportions of fine magnetite, which were distributed up to ~24° S by the Brazilian Coastal Current and admixed to coarser relict sediments of Pampean loessoidal origin. Grain-size analyses of all samples showed that sediment fractionation during transport and deposition had little impact on magnetic and element source characteristics. This study corroborates the high potential of the chosen approach to access sediment origin in regions with contrasting sediment sources, complex transport dynamics, and large grain-size variability.

The Debate on First Nations Education Funding: Mind the Gap (Working Paper 49)

It is at long last becoming part of the public discourse that improving living conditions and opportunities for First Nations communities in Canada is a national imperative. It is also widely recognized that the education is critical to fostering a better future for First Nations people. Yet, for many First Nations youth, particularly those on reserve, completing even high school is well beyond reach. The graduation rate of First Nations people living on reserve was 35.3 per cent as recently as 2011 compared with 78 per cent for the population as a whole. At the same time, the First Nations population is young and growing fast - in First Nations communities 49 per cent of the population is under 24 years of age compared to 30 per cent of the general population. Despite some incremental improvements in education success rates for First Nations students in recent years, the education gap between First Nations and the rest of the country is increasing. The concerns expressed in the 2011 Auditor General report continue to hold weight: "In 2004, we noted that at existing rates, it would take 28 years for First Nations communities to reach the national average. More recent trends suggest that the time needed may still be longer.

Revisiting the Late Jurassic-Early Cretaceous of the NW South Iberian Basin: new ages and sedimentary environments

The study of the Upper Jurassic-Lower Cretaceous deposits (Higueruelas, Villar del Arzobispo and Aldea de Cortés Formations) of the South Iberian Basin (NW Valencia, Spain) reveals new stratigraphic and sedimentological data, which have significant implications on the stratigraphic framework, depositional environments and age of these units. The Higueruelas Fm was deposited in a mid-inner carbonate platform where oncolitic bars migrated by the action of storms and where oncoid production progressively decreased towards the uppermost part of the unit. The overlying Villar del Arzobispo Fm has been traditionally interpreted as an inner platform-lagoon evolving into a tidal-flat. Here it is interpreted as an inner-carbonate platform affected by storms, where oolitic shoals protected a lagoon, which had siliciclastic inputs from the continent. The Aldea de Cortés Fm has been previously interpreted as a lagoon surrounded by tidal-flats and fluvial-deltaic plains. Here it is reinterpreted as a coastal wetland where siliciclastic muddy deposits interacted with shallow fresh to marine water bodies, aeolian dunes and continental siliciclastic inputs. The contact between the Higueruelas and Villar del Arzobispo Fms, classically defined as gradual, is also interpreted here as rapid. More importantly, the contact between the Villar del Arzobispo and Aldea de Cortés Fms, previously considered as unconformable, is here interpreted as gradual. The presence of Alveosepta in the Villar del Arzobispo Fm suggests that at least part of this unit is Kimmeridgian, unlike the previously assigned Late Tithonian-Middle Berriasian age. Consequently, the underlying Higueruelas Fm, previously considered Tithonian, should not be younger than Kimmeridgian. Accordingly, sedimentation of the Aldea de Cortés Fm, previously considered Valangian-Hauterivian, probably started during the Tithonian and it may be considered part of the regressive trend of the Late Jurassic-Early Cretaceous cycle. This is consistent with the dinosaur faunas, typically Jurassic, described in the Villar del Arzobispo and Aldea de Cortés Fms.

"Paseo por una guerra antigua" (Juan Antonio Bardem, 1948-49): una contramemoria de la Guerra Civil

Este artículo pretende demostrar en qué medida Paseo por una guerra antigua (1948-1949), la práctica de segundo curso del Instituto de Investigaciones y Experiencias Cinematográficas (IIEC) en la que Juan Antonio Bardem rueda a un joven mutilado caminando por las ruinas de la Ciudad Universitaria de Madrid, constituye un intento pionero de desmontar los relatos oficiales de la Guerra Civil Española y rescatar la memoria de los vencidos. Filmar las ruinas del campus madrileño en aquellos años era un acto sub­versivo, puesto que el Régimen había emprendido su reconstrucción para borrar las huellas del Madrid republicano y de la Guerra Civil, resignificando por completo el recinto universitario. Por tanto, en Paseo por una guerra antigua, Bardem intenta reapropiarse de un espacio que en la época iba imponiéndose como uno de los “lugares de memoria” del franquismo. Esta película se vale de la función documental del cine para inmortalizar unas ruinas que simbolizan la República y la guerra, para preservarlas de la muerte simbólica que representa su reconstrucción. Mostrar esas ruinas en 1948-1949 equivale a “materializar” el pasado, a traerlo al presente de la posguerra, en un proceso que recuerda a los planteamientos sobre la Historia de Walter Benjamin, para proponer una visión alternativa de la contienda. Se trata de una visión teñida de una memoria íntima, ya que la película es un paseo no solo por las ruinas sino también por los recuerdos de este joven mutilado. En suma, Bardem propone una contramemoria de la Guerra Civil.

Looking for Determinants of Ontological Security in the Spain of the Crisis

The concept of ontological security has a remarkable echo in the current sociology to describe emotional status of men of late modernity. However, the concept created by Giddens in the eighties has been little used in empirical research covering various sources of risk or uncertainty. In this paper, a scale for ontological security is proposed. To do this, we start from the results of a research focused on the relationship between risk, uncertainty and vulnerability in the context of the economic crisis in Spain. These results were produced through nine focus groups and a telephone survey with standardized questionnaire applied to a national sample of 2,408 individuals over 18 years. This work is divided into three main sections. In the fi rst, a scale has been built from the results of the application of different items present in the questionnaire used. The second part explores the relationships of the scale obtained with the variables further approximate the emotional dimensions of individuals. The third part observes the variables that contribute to changes in the scale: These variables show the structural feature of the ontological security.

The value of military oath in civil wars in Rome: The example of conflict 49-45 BC

During the civil war between Caesar and Pompey, the military oath which binds the soldier to his army is often openly violated. Yet despite this offense, commanders of armed struggle require recursively the oath to their men. Admittedly, this ritual act seems ineffective given the many desertions and mutinies identified, but military leaders use its symbolic and sacred meaning to legitimize one hand their “anti-republican” actions, on the other armies fighting in a context deemed impius.

Biopoética, cognición y emoción: integración conceptual y emergencia en "The crying of Lot 49" de Thomas Pynchon

Programa de doctorado: Nuevas perspectivas cognitivas en los estudios de lengua, literatura y traducción. La fecha de publicación es la fecha de lectura

Retinal nerve fiber layer analysis using GDx® in 49 patients with chronic phase DUSN

To describe retinal nerve fiber layer changes in late-stage diffuse unilateral subacute neuroretinitis eyes and compare these results with healthy eyes observed through nerve fiber analyzer (GDx®). Methods: This is a retrospective case-control study in which 49 eyes in late-stage diffuse unilateral subacute neuroretinitis were examined from May/97 to December/ 01. First, eyes with diffuse unilateral subacute neuroretinitis and healthy contralateral eyes (Control Group I) were statistically matched. Subsequently, eyes with diffuse unilateral subacute neuroretinitis were compared with eyes of healthy patients (Control Group II). Results: Eyes from Control Groups I and II had higher relative frequency of “within normal limits” status. Eyes from the diffuse unilateral subacute neuroretinitis (DUSN) Group had higher frequency of “outside normal limits” and “borderline” status. Control Groups I and II had absolute values different from the DUSN Group regarding all parameters (p<0.05), except for Symmetry in Control Groups I and II, Average thickness and Superior Integral in control group II. Conclusion: Patients with late-stage diffuse unilateral subacute neuroretinitis presented presumed decrease in nerve fiber layer thickness shown by GDx®. Retinal zones with larger vascular support and larger amount of nerve fibers presented higher decrease in the delay of the reflected light measured by the nerve fiber analyzer