Storm-induced sediment gravity flows at the head of the Eel submarine canyon, northern California margin

10 pages, 5 figuresAs part of the STRATAFORM program, a bottom-boundary layer (BBL) tripod was deployed at 120 m depth in the northern thalweg of the Eel Canyon during winter 2000. Increases of the near-bottom suspended-sediment concentrations (SSC) recorded at the canyon head were not directly related to the Eel River discharge, but were clearly linked to the occurrence of storms. BBL measurements revealed that during intensifications of the wave orbital velocity, sediment transport at the head of the canyon occurred as sediment gravity flows directed down-canyon. Observational evidence for near-bed sediment gravity-flow transport included an increase toward the bed of the down-canyon component of wave-averaged velocity and high estimated SSC. At higher sampling frequencies (1 Hz), the current components during these events fluctuated at the same periodicity as the pressure, reflecting a clear influence of the surface-wave activity on the generation and maintenance of the sediment gravity flows. The origin of such flows is not related to the formation of fluid muds on the shelf or to intense wave-current sediment resuspension around the canyon head region. Rather, liquefaction of sediment deposited at the head of the canyon (induced by wave-load excess pore water pressures during storms) combined with elevated slopes around the canyon head appear to be the mechanisms initiating sediment transport. The resulting fluidized-sediment layer can easily be eroded, entrained into the water column, and transported down-canyon as a sediment gravity flow. Results from this study reveal that storm-induced sediment gravity flows occur periodically in the Eel Canyon head, and suggest that this kind of sediment transport process can occur in other submarine canyons more frequently than previously expected. Copyright 2004 by the American Geophysical UnionThis work has been funded by the Office of Naval Research, Marine Geology and Geophysics Program, grants N00014-95-1-0418 and N00014-99-1-0028, as part of the STRATAFORM program. P. Puig received financial support from a Fulbright scholarship provided by the Spanish Ministry of Education and CulturePeer Reviewe

Vector-borne disease surveillance in livestock populations: A critical review of literature recommendations and implemented surveillance (BTV-8) in five European countries

Preparedness against vector-borne threats depends on the existence of a long-term, sustainable surveillance of vector-borne disease and their relevant vectors. This work reviewed the availability of such surveillance systems in five European countries (Denmark, France, The Netherlands, Sweden and United Kingdom, part of the CoVetLab network). A qualitative assessment was then performed focusing on surveillance directed particularly to BTV-8. Information regarding surveillance activities were reviewed for the years 2008 and 2012. The results were then complemented with a critical scoping review of the literature aimed at identifying disease surveillance strategies and methods that are currently suggested as best suited to target vector-borne diseases in order to guide future development of surveillance in the countries in question. Passive surveillance was found to be efficient for early detection of diseases during the early phase of introduction into a free country. However, its value diminished once the disease has been established in a territory. Detection of emerging diseases was found to be very context and area specific, and thus active surveillance designs need to take the available epidemiological, ecological and entomological information into account. This was demonstrated by the effectiveness of the bulk milk surveillance in detecting the first case in Sweden, highlighting the need for output based standards to allow the most effective, context dependent, surveillance strategies to be used. Preparedness was of fundamental importance in determining the timeliness of detection and control in each country and that this in turn was heavily influenced by knowledge of emerging diseases in neighboring countries. Therefore it is crucial to share information on outbreaks between researchers and decision-makers and across borders continuously in order to react timely in case of an outbreak. Furthermore, timely reaction to an outbreak was heavily influenced by availability of control measures (vaccines), which is also strengthened if knowledge is shared quickly between countries. The assessment of the bluetongue surveillance in the affected countries showed that the degree of voluntary engagement varied, and that it is important to engage the publicby general awareness and dissemination of results. The degree of engagement will also aid in establishing a passive surveillance system

Neurodevelopmental outcome at 5 years of age after general anaesthesia or awake-regional anaesthesia in infancy (GAS)trial

Background: In laboratory animals, exposure to most general anaesthetics leads to neurotoxicity manifested by neuronal cell death and abnormal behaviour and cognition. Some large human cohort studies have shown an association between general anaesthesia at a young age and subsequent neurodevelopmental deficits, but these studies are prone to bias. Others have found no evidence for an association. We aimed to establish whether general anaesthesia in early infancy affects neurodevelopmental outcomes. Methods: In this international, assessor-masked, equivalence, randomised, controlled trial conducted at 28 hospitals in Australia, Italy, the USA, the UK, Canada, the Netherlands, and New Zealand, we recruited infants of less than 60 weeks' postmenstrual age who were born at more than 26 weeks

Impact of Power Structure On Supply Chain Performance and Consumer Surplus

In this study, we consider a game theory based framework to model power in a supply chain with price‐dependent stochastic demand and to investigate how power structures (dominant retailer, dominant manufacturer, or balanced power) and demand models (expected demand and demand shock) affect supply chain efficiency, members’ profits, and consumer surplus. We analyze all of the problems in this framework and characterize their equilibrium outcomes. In comparison, we demonstrate that a firm often benefits from its power except that a power manufacturer might suffer in a supply chain with isoelastic demand and additive shock. A balanced power structure is often conducive to the whole supply chain, but this structure might not perform very well in a supply chain with isoelastic demand and additive shock. Power structures and demand models act on consumers in much the same manner that they do on supply chain efficiency. In other words, consumers often prefer a balanced power structure and thereby do not profit from power retailers. Additionally, we find that the retail price can play a pivotal role in determining supply chain efficiency and consumer surplus. Specifically, the lower the retail price, the higher the supply chain efficiency and consumer surplus. In contrast, the service level has a less preeminent influence on both of them