1,864 research outputs found
Dune-associated sand fluxes at the nearshore termination of a banner sand bank (Helwick Sands, Bristol Channel)
Comparing the post-WWII publication histories of oceanography and marine geoscience
From Springer Nature via Jisc Publications RouterHistory: received 2018-09-10, registration 2020-04-30, pub-electronic 2020-05-26, online 2020-05-26, pub-print 2020-08Publication status: PublishedAbstract: Oceanography and marine geosciences are closely related subjects, though they have had differing influences. The UK, which has experienced the financial benefits of North Sea oil and gas, while also having an extensive fishing industry and a science base linked to other English-speaking countries and European countries, potentially illustrates some changing influences and collaborative tendencies well. In this article, differences in article publication rates and collaborative tendencies, both globally and for the UK, are examined using the Web of Science™, Scopus™ and Georef™ for the period 1946–2018. The results show that publication rates of global oceanography articles rose exponentially faster than all global scientific publishing from the mid-1960s to 1980. Subsequently, the exponential rate of increase slowed though has remained faster than global science publishing. Global Marine Geoscience publication rates increased into the late 1980s, but have since declined. UK oceanography has roughly followed global trends, though its share of global oceanographic publishing declined from 28% in the 1950s to 8% in 2018. UK Marine Geoscience publishing has also generally followed global trends for that field. However, its share of global publications abruptly increased from 4.9% (average 1960–1980) to 13.2% by 1990, largely due to articles arising from UK participation in the Deep-Sea Drilling Project and Ocean Drilling Program. Oceanography and marine geoscience have also experienced strongly differing histories of collaborative articles over the last four decades. While oceanographic articles co-authored with researchers in other countries have been steadily increasing as a share of total UK Oceanography articles, those of marine geoscience peaked in 1990 and have since declined, though remained at high levels similar to those experienced by 2018 in Oceanography. Comparing global publication rates in both fields with measures of data and sample collection at sea suggests fundamental changes occurred in the way research was carried out. For example, Marine Geoscience publication rates were strongly correlated with geophysical track-line distances for the decade until ~1970, but were inversely correlated for the decade after then. This reflects, for example, the development of plate tectonics, which partly involved analysis of existing marine geophysical data, improved equipment capabilities and the increased role of scientific drilling
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Working Memory and the Suppression of Reflexive Saccades
Conscious behavioral intentions can frequently fail under conditions of attentional depletion. In attempting to trace the cognitive origin of this effect, we hypothesized that failures of action control—specifically, oculomotor movement—can result from the imposition of fronto-executive load. To evaluate this prediction, participants performed an antisaccade task while simultaneously completing a working-memory task that is known to make variable demands on prefrontal processes (n-back task, see Jonides et al., 1997).
The results of two experiments are reported. As expected, antisaccade error rates were increased in accordance with the fronto-executive demands of the n-back task (Experiment 1). In addition, the debilitating effects of working-memory load were restricted to the inhibitory component of the antisaccade task (Experiment 2). These findings corroborate the view that working memory operations play a critical role in the suppression of prepotent behavioral responses.Psycholog
Caracterização morfológica da plataforma da ilha do Faial
A plataforma insular do Faial foi cartografada com recurso a um vasto conjunto de dados geofĂsicos e geolĂłgicos. A análise da
morfologia da plataforma permitiu perceber quais os factores que mais contribuiram para a sua evolução
Lava penetrating water: Submarine lava flows around the coasts of Pico Island, Azores
Bathymetry data collected with a multibeam echo sounder around Pico Island, Azores (Portugal), reveal a remarkable series of lava flows on the island's shelf with a variety of pristine structures that suggest how lava behaves on entering water. Many flows are dendritic in plan view, some with channels and tumuli. Dendritic geometries are interpreted to arise from flow fronts repeatedly arrested by enhanced cooling and magma pressure subsequently causing new breakouts. Cascades of elongated flow fingers also occur, with individual fingers of comparable diameters to the largest known megapillows. Some flows have wide transverse clefts, in cases separating flows into segments, which are interpreted as caused by their upper surfaces having solidified, while their still-fluid cores allowed the surfaces to extend. A number of flows moved onto the shelf as large bodies, stopped, and then sourced smaller lobes forming the dendritic patterns. This two-stage evolution and the tumuli (which lie on a low gradient immediately below a steep nearshore gradient) suggest that, after initial emplacement and development of a crust by cooling, some flows pressurized. Once movements ceased and viscous stresses dissipated, magma static pressure developed from the weight of flow interiors passing over cliffs and nearshore gradients. One group of flows traverses the island's submarine slope, so direct supply of lava to the slopes is possible, although volumetrically how important it is to the island's internal composition is difficult to tell from these data. On the basis of observed strong surf erosion of historical flows, these delicate structures probably could not have survived passage through a moving sea level unmodified by erosion so they are unlikely to be pre-Holocene subaerial flows. They are interpreted to have formed in the Holocene from flows penetrating sea level or possibly some from nearshore tube openings or vents. Such flows and abundant clastic deposits are ephemeral features that become remobilized by surf during times of lower sea level. The shelves of active volcanic islands are therefore active geologically and are far from being simple products of erosional truncation as was once envisaged
Equatorial Pacific gravity lineaments: interpretations with basement topography along seismic reflection lines
The central equatorial Pacific is interesting for studying clues to upper mantle processes, as the region lacks complicating effects of continental remnants or major volcanic plateaus. In particular, the most recently produced maps of the free-air gravity field from satellite altimetry show in greater detail the previously reported lineaments west of the East Pacific Rise (EPR) that are aligned with plate motion over the mantle and originally suggested to have formed from mantle convection rolls. In contrast, the gravity field 600 km or farther west of the EPR reveals lineaments with varied orientations. Some are also parallel with plate motion over the mantle but others are sub-parallel with fracture zones or have other orientations. This region is covered by pelagic sediments reaching ~ 500–600 m thickness so bathymetry is not so useful for seeking evidence for plate deformation across the lineaments. We instead use depth to basement from three seismic reflection cruises. In some segments of these seismic data crossing the lineaments, we find that the co-variation between gravity and basement depth is roughly compatible with typical densities of basement rocks (basalt, gabbro or mantle), as expected for some explanations for the lineaments (e.g., mantle convection rolls, viscous asthenospheric inter-fingering or extensional deformation). However, some other lineaments are associated with major changes in basement depth with only subtle changes in the gravity field, suggesting topography that is locally supported by varied crustal thickness. Overall, the multiple gravity lineament orientations suggest that they have multiple origins. In particular, we propose that a further asthenospheric inter-fingering instability mechanism could occur from pressure variations in the asthenosphere arising from regional topography and such a mechanism may explain some obliquely oriented gravity lineaments that have no other obvious origin
Dissociable Neural Substrates for Agentic versus Conceptual Representations of Self
Although humans generally experience a coherent sense of selfhood, we can nevertheless articulate different aspects of self. Recent research has demonstrated that one such aspect of self—conceptual knowledge of one's own personality traits—is subserved by ventromedial prefrontal cortex (vMPFC). Here, we examined whether an alternative aspect of “self”—being an agent who acts to achieve one's own goals—relies on cognitive processes that overlap with or diverge from conceptual operationalizations of selfhood. While undergoing fMRI, participants completed tasks of both conceptual self-reference, in which they judged their own or another person's personality traits, and agentic self-reference, in which they freely chose an object or watched passively as one was chosen. The agentic task failed to modulate vMPFC, despite producing the same memory enhancement frequently observed during conceptual self-referential processing (the “self-reference” effect). Instead, agentic self-reference was associated with activation of the intraparietal sulcus (IPS), a region previously implicated in planning and executing actions. Experiment 2 further demonstrated that IPS activity correlated with later memory performance for the agentic, but not conceptual, task. These results support views of the “self” as a collection of distinct mental operations distributed throughout the brain, rather than a unitary cognitive system
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