Longest sediment flows yet measured show how major rivers connect efficiently to deep sea

Here we show how major rivers can efficiently connect to the deep-sea, by analysing the longest runout sediment flows (of any type) yet measured in action on Earth. These seafloor turbidity currents originated from the Congo River-mouth, with one flow travelling >1,130 km whilst accelerating from 5.2 to 8.0 m/s. In one year, these turbidity currents eroded 1,338-2,675 [>535-1,070] Mt of sediment from one submarine canyon, equivalent to 19–37 [>7–15] % of annual suspended sediment flux from present-day rivers. It was known earthquakes trigger canyon-flushing flows. We show river-floods also generate canyon-flushing flows, primed by rapid sediment-accumulation at the river-mouth, and sometimes triggered by spring tides weeks to months post-flood. It is demonstrated that strongly erosional turbidity currents self-accelerate, thereby travelling much further, validating a long-proposed theory. These observations explain highly-efficient organic carbon transfer, and have important implications for hazards to seabed cables, or deep-sea impacts of terrestrial climate change.

This paper analyses the longest sediment flows measured in action on Earth. These seabed flows were caused by floods and spring tides, and flushed prodigious sediment and carbon volumes into the deep sea, as they accelerated for a thousand kilometres.

First source-to-sink monitoring shows dense head controls sediment flux and runout in turbidity currents

Until recently, despite being one of the most important sediment transport phenomena on Earth, few direct measurements of turbidity currents existed. Consequently, their structure and evolution were poorly understood, particularly whether they are dense or dilute. Here, we analyze the largest number of turbidity currents monitored to date from source to sink. We show sediment transport and internal flow characteristic evolution as they runout. Observed frontal regions (heads) are fast (>1.5 m/s), thin (<10 m), dense (depth averaged concentrations up to 38%_vol), strongly stratified, and dominated by grain-to-grain interactions, or slower (<1 m/s), dilute (<0.01%_vol), and well mixed with turbulence supporting sediment. Between these end-members, a transitional flow head exists. Flow bodies are typically thick, slow, dilute, and well mixed. Flows with dense heads stretch and bulk up with dense heads transporting up to 1000 times more sediment than the dilute body. Dense heads can therefore control turbidity current sediment transport and runout into the deep sea.

Family Adaptation to a Child's Transplant: Pretransplant Phase

The purpose of this study was to explore the relationship between family stress, family coping, social support, perception of stress, and family adaptation from the mother's perspective during the pretransplant period in the context of the Double ABC-X Model of Family Adaptation. The process of seeking a transplant for a child is very stressful, and before interventions can be developed, clinicians need to understand how aspects of family life are affected. Twenty-nine mothers whose children were being evaluated for a liver transplant constituted the sample for this exploratory study. Higher family strains, fewer coping skills, and higher perception of stress were related to more unhealthy family adaptation during the pre-transplant phase. Data point to the need for close evaluation not only for the child's needs but for the family's needs as the family begins the process of seeking a transplant for the child.

Portfolio assessment in medical students' final examinations

The introduction of an outcome-based approach to education at Dundee Medical School in Scotland instigated a search for assessment methods that would appropriately assess the students' achievements in terms of the learning outcomes. Portfolio assessment has been developed for this purpose and has been adopted for the summative assessment of students in their final examination in Dundee. The contents of the portfolio and the assessment process have been defined and the first cohort of students to be assessed in this way has been studied. The evaluation of the approach demonstrated strong staff support. Students were also positive although with some reservations. It is concluded that portfolio assessment is a powerful approach to assessing a range of curriculum outcomes not easily assessed by other methods and is worthy of inclusion in the assessor's toolkit.

Family adaptation to a child's transplant: pretransplant phase

The purpose of this study was to explore the relationship between family stress, family coping, social support, perception of stress, and family adaptation from the mother's perspective during the pretransplant period in the context of the Double ABC-X Model of Family Adaptation. The process of seeking a transplant for a child is very stressful, and before interventions can be developed, clinicians need to understand how aspects of family life are affected. Twenty-nine mothers whose children were being evaluated for a liver transplant constituted the sample for this exploratory study. Higher family strains, fewer coping skills, and higher perception of stress were related to more unhealthy family adaptation during the pre-transplant phase. Data point to the need for close evaluation not only for the child's needs but for the family's needs as the family begins the process of seeking a transplant for the child.

Acute angle closure glaucoma masquerading as systemic illness

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