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Abstract Analysis of physical properties measured on cores and on discrete samples collected by the Ocean Drilling Programme (ODP) Leg 178 on the Pacific margin of the Antarctic Peninsula reveals anomalous down-hole curves of porosity, density, water content, and P-wave velocity. These indicate an overall trend of increasing porosity with depth and suggest that the drifts are mostly undercompacted. In one of the two boreholes analysed, a sharp decrease in porosity, matching increasing bulk sediment density and increasing compressional velocity occurs towards the base of the hole, which corresponds to a bottom-simulating reflector in the seismic section. Analysis of seismic reflection, down-hole logging, geotechnical and mineralogical data from two drilling sites indicates that the observed anomalous consolidation trends are a consequence of the presence of biogenic silica (diatom and radiolarian skeletons) even with a small to moderate amount. Above the bottom-simulating reflector, intergranular contacts among whole or broken siliceous microfossils prevent normal sediment consolidation. Diagenetic alteration of biogenic opal-A to opal-CT causes a dramatic reduction of intra- and interskeletal porosity allowing sediments to consolidate at depth. This results in overpressuring and a decrease in the effective stress. Excess fluids are expelled towards the sediment surface through near vertical, small throw normal faults extending from the diagenetic front to the seafloor and affecting the stability of the submarine slope in the form of gravitational creep along a weakened surface. This work shows how physical properties of shallow fine-grained marine sediments can be analysed as basin-wide indicators of biogenic silica abundance. The diagenetic alteration of siliceous microfossils is a possible cause of slope instability along world continental margins where bottom-simulating reflectors related to silica diagenesis are present at a regional scale. [ABSTRACT FROM AUTHOR]

We present two time series of bottom current and temperature collected 8 m above the seabed on either side of a large sediment drift located on the continental rise of the Pacific margin of the Antarctic Peninsula. The mean current speed is comparable (6.2 cm s-1 and 6.1 cm s-1 respectively), but the mean direction differs by about 121 deg. The direction of mean flow follows the bathymetric contour, and the maximum speed never exceeds 20 cm s-1 (below the typical benthic storm threshold). The potential temperature is remarkably stable (0.11 -+ 0.01 deg. C and0.13 -+ 0.02 deg. C at the two sites). The cross-covariance indicates a significant peak at 20.2 days lag, slightlylonger than the travel time of 18.7 days calculated between the two stations following the isobaths (98.4 km) and thus providing evidencefor the topographic control on bottom water flow. The observed bottom water flow is consistent with deposition of Holocene hemipelagic sediments of the 'drift maintenance' stage. Indicators for palaeoceanographic conditions during glacial periods of the 'drift maintenance' stage and the older 'drift growth' stage are at present too scarce to understand fully how the past oceanographic conditions influenced theevolution of the drifts. [ABSTRACT FROM AUTHOR]

Abstract: Side scan sonar, high-resolution seismic and multibeam data collected off the coast of Asinara Island in the northernmost part of Sardinia have revealed the occurrence of four distinct acoustical patterns that can be related to four main sea-bed types. The four facies represent fine sand (Type A), medium to coarse sand (Type B), patchy sand cover between basement outcrops (Type C) and a predominantly sandy sea-floor colonized by the seagrass Posidonia Oceanica (Type P). The distribution of the sea-bed types indicates that the study area is characterized by a rather complex morphological setting. A remarkable physiographic difference exists between the eastern and western sector of the island, with the latter being affected by strong, westerly winds, mainly the so-called “Mistral”. The wave climate in this area is dominated by wind waves, which can reach a maximum height of 8m during winter storms. Sediments are mobilized at water depths greater than 30m from the sea surface during these energetic oceanographic regimes. We infer that dune fields and sand ribbons are deposited by strong offshore flows along the sea-bed resulting as a consequence of wave- and wind-induced onshore water transport. [Copyright &y& Elsevier]

Interactions between along-slope bottom currents and down-slope turbidity flows can create a myriad of features and deposits. Despite numerous efforts to differentiate contourites from turbidites and mixed features, reliable diagnostic criteria are still lacking from the stratigraphic and sedimentological viewpoints. The main aim of this study is to develop criteria to differentiate mixed, along-slope-, and down-slope-generated elements from other deep-water deposits across bathymetric, seismic and sediment core data. Mixed (turbidite-contourite) systems can be placed in three main groups based on their location, dimensions, elongation, lateral migration, spatial and temporal variability: 1) turbidite-dominated mixed systems , 2) synchronous systems , and 3) contourite-dominated mixed systems. The persistence of bottom currents —in addition to their velocity, direction, and hydrodynamic fluctuations— is responsible for entraining and redistributing fine-grained particles, carried in suspension by coeval turbidity flows, and reworking previously deposited sediments. Changes in turbidity current velocity, frequency, and duration condition the provision of sediments and development of turbidites along mixed systems. Several preliminary models are also being proposed in this study, in order to enhance our understanding of the lateral and vertical distribution of mixed systems across the sedimentary record. Interactions between along- and down-slope processes may be synchronous, asynchronous or passive. Synchronous interactions typically occur within the same physiographic setting and the two processes interact coevally in space and time. Asynchronous interactions are also common across the modern and ancient sedimentary records, as bottom currents sweep across the deep-water environments during breaks of the turbidity flows. Passive interactions occur along the distal margins of mixed systems, or when the two processes occur near each other but do not cross over in time. Further controlling factors are held to be influential in the evolution of mixed systems at the short- to long-term; varying degrees of confinement, sediment supply or climatic fluctuations can generate cyclic stacking patterns and affect their overall dimensions. Accordingly, mixed systems feature more complex geometries than previously believed, as interactions may generate new secondary processes and features. Such systems form potential plays and may become future targets for energy geosciences and other research fields. [Display omitted] • Comprehensive review of previously known mixed systems and new undocumented cases. • Ancient and modern mixed systems share morphological traits and stacking patterns. • Mixed systems may range from turbidite- to contourite-dominated settings. • Turbidity and bottom current interaction may be synchronous, asynchronous or passive. • Unprecedent summary and reference list of all examples identified until the present. [ABSTRACT FROM AUTHOR]

The Paleogene carbonate “megabreccia” units of the Friuli Basin are composite deposits produced by catastrophic shallow-water carbonate platform collapses re-deposited in relatively deep-water inner foredeep settings developed at the front of the advancing Dinaric thrust system. These thick, basin-wide mass transport deposits (MTDs) record the catastrophic emplacement of bipartite slide masses, comprising a lower coherent/cohesive blocky flow and an upper grain/turbulent flow. We here present the results of micro- to outcrop-scale structural analyses, constrained by stratigraphic and sedimentologic observations, performed to identify the internal deformation mechanisms and the emplacement processes of four of the largest MTDs exposed in two large three-dimensional outcrops: the Vernasso (NE Italy) and Anhovo (W Slovenia) open-pit quarries. Our results reveal a variety of primary (sedimentary) soft sediment deformation structures testifying fluid overpressure conditions within the brecciated, fine-grained matrix that sustain, intrude and surround slide blocks and clasts. Meso-scale structural analyses unraveled paleo-transport directions toward the N for the Vernasso quarry and toward the S for the Anhovo quarry. This suggests a forced propagation of the mass transport events controlled by the shape of basin, and reinforces the interpretation of different source areas related to multiple collapses from a carbonate platform rimming the southeastern tip of the basin. These units are thought to represent exhumed fossil examples of the MTDs extensively mapped in the present-day, carbonate-dominated continental margins, and thus, considered as reliable analogues for integrated studies. [ABSTRACT FROM AUTHOR]

The intrusion of relatively warm water onto the continental shelf is widely recognized as a threat to Antarctic ice shelves and glaciers grounded below sea level, as enhanced ocean heat increases their basal melt. While the circulation of warm water has been documented on the East Antarctic continental shelf, the modes of warm water transport from the deep ocean onto the shelf are still uncertain. This makes predicting the future responses of major East Antarctic marine-grounded glaciers, such as Totten and Ninnis glaciers, particularly challenging. Here, we outline the key role of submarine canyons to convey southward flowing currents that transport warm Circumpolar Deep Water toward the East Antarctic shelf break, thus facilitating warm water intrusion on the continental shelf. Sediment drifts on the eastern flank of the canyons provide evidence for sustained southward-directed flows. These morpho-sedimentary features thus highlight areas potentially prone to enhanced ocean heat transport toward the continental shelf, with repercussions for past, present, and future glacial melting and consequent sea level rise., (© 2024. The Author(s).)

Antarctica's continental margins pose an unknown submarine landslide-generated tsunami risk to Southern Hemisphere populations and infrastructure. Understanding the factors driving slope failure is essential to assessing future geohazards. Here, we present a multidisciplinary study of a major submarine landslide complex along the eastern Ross Sea continental slope (Antarctica) that identifies preconditioning factors and failure mechanisms. Weak layers, identified beneath three submarine landslides, consist of distinct packages of interbedded Miocene- to Pliocene-age diatom oozes and glaciomarine diamicts. The observed lithological differences, which arise from glacial to interglacial variations in biological productivity, ice proximity, and ocean circulation, caused changes in sediment deposition that inherently preconditioned slope failure. These recurrent Antarctic submarine landslides were likely triggered by seismicity associated with glacioisostatic readjustment, leading to failure within the preconditioned weak layers. Ongoing climate warming and ice retreat may increase regional glacioisostatic seismicity, triggering Antarctic submarine landslides., (© 2023. The Author(s).)

The Southern Ocean surrounding Antarctica is a region that is key to a range of climatic and oceanographic processes with worldwide effects, and is characterised by high biological productivity and biodiversity. Since 2013, the International Bathymetric Chart of the Southern Ocean (IBCSO) has represented the most comprehensive compilation of bathymetry for the Southern Ocean south of 60°S. Recently, the IBCSO Project has combined its efforts with the Nippon Foundation - GEBCO Seabed 2030 Project supporting the goal of mapping the world's oceans by 2030. New datasets initiated a second version of IBCSO (IBCSO v2). This version extends to 50°S (covering approximately 2.4 times the area of seafloor of the previous version) including the gateways of the Antarctic Circumpolar Current and the Antarctic circumpolar frontal systems. Due to increased (multibeam) data coverage, IBCSO v2 significantly improves the overall representation of the Southern Ocean seafloor and resolves many submarine landforms in more detail. This makes IBCSO v2 the most authoritative seafloor map of the area south of 50°S., (© 2022. The Author(s).)

Bathymetry (seafloor depth), is a critical parameter providing the geospatial context for a multitude of marine scientific studies. Since 1997, the International Bathymetric Chart of the Arctic Ocean (IBCAO) has been the authoritative source of bathymetry for the Arctic Ocean. IBCAO has merged its efforts with the Nippon Foundation-GEBCO-Seabed 2030 Project, with the goal of mapping all of the oceans by 2030. Here we present the latest version (IBCAO Ver. 4.0), with more than twice the resolution (200 × 200 m versus 500 × 500 m) and with individual depth soundings constraining three times more area of the Arctic Ocean (∼19.8% versus 6.7%), than the previous IBCAO Ver. 3.0 released in 2012. Modern multibeam bathymetry comprises ∼14.3% in Ver. 4.0 compared to ∼5.4% in Ver. 3.0. Thus, the new IBCAO Ver. 4.0 has substantially more seafloor morphological information that offers new insights into a range of submarine features and processes; for example, the improved portrayal of Greenland fjords better serves predictive modelling of the fate of the Greenland Ice Sheet.

Objectives: If a patient wishes to refuse treatment in the prehospital setting, prehospital providers and consulting emergency physicians must establish that the patient possesses the capacity to do so. The objective of this study is to assess agreement among prehospital providers and emergency physicians in performing patient capacity assessments., Methods: This study involved 139 prehospital providers and 28 emergency medicine physicians. Study participants listened to 30 medical control calls pertaining to patient capacity and were asked to interpret whether the patients in the scenarios had the capacity to refuse treatment. Participants also reported their comfort level using modified Likert scales. Inter-rater reliability was calculated utilizing Fleiss' and Model B kappa statistics. Fisher's exact tests were used to calculate p-values comparing the proportion in each cohort that responded "no capacity." Primary outcomes included inter-rater reliability in the physician and prehospital provider cohorts., Results: The inter-rater agreement between the physicians was low (Fleiss' kappa = 0.31, standard error [SE] =0.06; model-based kappa = 0.18, SE = 0.04). Agreement was similarly low for the 135 prehospital providers (Fleiss' kappa = 0.30, SE = 0.06; model-based kappa = 0.28, SE = 0.04). The difference between the proportion of physicians and prehospital providers who responded "no capacity" was statistically significant in five of 30 scenarios. Median prehospital provider and physician confidence, on a 1 to 4 scale, was 2.00 (Q1-Q3 = 1.00-3.00 for prehospital providers and Q1-Q3 =1.0-2.0 for physicians)., Conclusions: There was poor inter-rater reliability in capacity determination between and among the prehospital provider and physician cohorts. This suggests that there is need for additional study and standardization of this task., (© 2020 by the Society for Academic Emergency Medicine.)

Objective: The goal of this study is to describe complications and outcomes of prehospital ketamine use for agitation as compared to other methods of physical or chemical restraint such as haloperidol plus benzodiazepine or physical restraint only., Methods: We conducted a single-center retrospective review of patient encounters in which restraint was administered in the prehospital setting. At the beginning of our study window, only physical restraint was available to paramedics managing agitated patients but subsequently, haloperidol and benzodiazepines were introduced, followed by ketamine 2 years later. By comparing patients before and after each transition, we divided subjects into 3 cohorts based on restraint type: physical restraint, haloperidol plus benzodiazepine, and ketamine. Demographic data were collected, and outcome measures included intubation rate, need for additional physical or chemical restraint, emergency department (ED) length of stay, need for hospital admission, and employee injury., Results: Of 214 subjects included in the study, 95 patients were administered ketamine, 68 received haloperidol and benzodiazepine, and 51 were physically restrained. Eleven of the patients (11.6%) who received ketamine were intubated. Compared to patients who received haloperidol plus benzodiazepine, patients who received ketamine were more likely to be intubated (odds ratio [OR] = 8.77, 95% confidence interval [CI], 1.10-69.68) and were more likely to require additional chemical restraint when compared to haloperidol/benzodiazepine or physical restraint only (OR =2.94, 95% CI, 1.49-5.80, and OR =2.15, 95% CI, 1.07-4.31, respectively). There were no differences between the 2 chemical sedation groups in terms of ED length of stay or hospital admission rate., Conclusions: This study demonstrates a lower intubation rate in patients administered ketamine than prior literature in association with a lower weight-based dosing regimen. Ketamine use was correlated with a higher frequency of intubation and a greater need for additional chemical restraint when compared with other restraint modalities, though exogenous factors such as provider preference may have impacted this result. There was no difference in ED length of stay or admission rate between the ketamine and haloperidol plus benzodiazepine groups. Further prospective study is needed to determine whether there is a subset of patients for whom ketamine would be beneficial compared to other therapies.

The Barents Sea Ice Sheet was a marine-based ice sheet, i.e., it rested on the Barents Sea floor during the Last Glacial Maximum (21 ky BP). The Bjørnøyrenna Ice Stream was the largest ice stream draining the Barents Sea Ice Sheet and is regarded as an analogue for contemporary ice streams in West Antarctica. Here, the retreat of the Bjørnøyrenna Ice Stream is simulated by means of two numerical ice sheet models and results assessed against geological data. We investigate the sensitivity of the ice stream to changes in ocean temperature and the impact of grounding-line physics on ice stream retreat. Our results suggest that the role played by sub-shelf melting depends on how the grounding-line physics is represented in the models. When an analytic constraint on the ice flux across the grounding line is applied, the retreat of Bjørnøyrenna Ice Stream is primarily driven by internal ice dynamics rather than by oceanic forcing. This suggests that implementations of grounding-line physics need to be carefully assessed when evaluating and predicting the response of contemporary marine-based ice sheets and individual ice streams to ongoing and future ocean warming.

Cilia and flagella are highly conserved motile and sensory organelles in eukaryotes, and defects in ciliary assembly and motility cause many ciliopathies. The two-headed I1 inner arm dynein is a critical regulator of ciliary and flagellar beating. To understand I1 architecture and function better, we analyzed the 3D structure and composition of the I1 dynein in Chlamydomonas axonemes by cryoelectron tomography and subtomogram averaging. Our data revealed several connections from the I1 dynein to neighboring structures that are likely to be important for assembly and/or regulation, including a tether linking one I1 motor domain to the doublet microtubule and doublet-specific differences potentially contributing to the asymmetrical distribution of dynein activity required for ciliary beating. We also imaged three I1 mutants and analyzed their polypeptide composition using 2D gel-based proteomics. Structural and biochemical comparisons revealed the likely location of the regulatory IC138 phosphoprotein and its associated subcomplex. Overall, our studies demonstrate that I1 dynein is connected to multiple structures within the axoneme, and therefore ideally positioned to integrate signals that regulate ciliary motility.

This article describes the development of a behavior rating scale, which was designed to measure children's behaviors during a blood sampling procedure. Trained observers were able to reliably use the behavior rating scale while observing children's behaviors during blood sampling in a pediatric hospital. Evidence of the instrument's validity was found in a treatment study. In that experiment, youngsters were prepared for the blood sampling procedures by viewing films. Those watching coping or mastery models before blood sampling evidenced significantly higher adaptive responses on the behavior rating scale than those who watched a control film. The behavior rating scale was also significantly related to a global rating and a self-report measure, but not to a physiologic index of anxiety. In summary, the constructed behavior rating scale appears to be a reliable and valid instrument for assessing children's behavior during blood sampling procedures.