Gas hydrate systems respond slowly to seafloor warming

In a marine environment, gas hydrates are stable at certain pressure (sea level) and temperature (bottom water temperature) conditions. Changes in these conditions may result in the destabilization of the gas hydrates. In this study we investigate the temporal response of a continental margin gas hydrate reservoir to changes in the pressure and/or temperature regime, considering the latent heat of hydrate dissociation and the long response times to conductive heat transport in submarine sediments. Gas hydrates and the surrounding sediments do not instantly respond to changing environmental conditions. A vertical subsoil column without gas hydrates needs more than 5,000 years to adapt its temperature profile to an increase in seafloor temperature. A vertical subsoil column containing gas hydrates has the same response time if the stability of the hydrates is not affected. Although, when gas hydrates stability is affected due to changes in their environment, the response time to these changes is extended. Destabilized gas hydrates will dissociate into methane gas and water. The dissociation process happens at a constant temperature and requires a lot of energy (heat). Dissociation of gas hydrates thus delays the response time of the surrounding subsoil; up to 100,000 years may pass before the temperature profile completely adapted to the changed environmental parameters. Because of this slow response to changes in environmental parameters, gas hydrate dissociation cannot be regarded as the trigger to global warming at the end of glacial and stadial periods and gas hydrate dissociation cannot be responsible for the high observed atmospheric methane concentrations in ice core records, as has been postulated in a number of high-profile publications

PCBs still sticking around

C

Turn the tide: scientific research towards an integrated plan for the Upper-Seascheldt

During the last 150 years the Scheldt estuary has seen many changes either to claim land for urban or agricultural development or to improve the navigability. From the 1950’s onwards the most important changes to the character of the estuary could be attributed to infrastructural works such as dike construction and deepening. Even though cause–effect relationships are difficult to determine it is largely accepted that, besides reclamations, the main contribution to the loss of habitat can be attributed to the increase in tidal amplitude. In various studies the relationship between tidal amplification and large scale engineering works, including deepening, (downstream) sand extraction, embankments and straightening works, has been pointed out. It is clear that anthropogenic changes to the system can have serious consequences to the state of the estuary and that future works need to be prepared in a conscious and sustainable manner in order to avoid further tidal amplification.Within the framework of the project “Integrated Plan Upper-Seascheldt” commissioned by the Seascheldt division of the Waterwegen & Zeekanaal NV, it is investigated how navigability can be improved (to class Va) without negative effects to nature and safety against flooding. It is the goal of this integrated study to look for synergy in order to mitigate negative impacts of the proposed measures or even to improve the functioning of the system. In the last 10 years already various environmental measures like de-poldering are being implemented under the SIGMA-Plan.This paper will discuss the evolution of the Seascheldt in relation to historical anthropogenic changes. It will focus on the observed changes in water level, bathymetry, habitats (salt marshes) and sediment concentrations. In addition, the paper will outline the project plan to investigate whether de-poldering projects and other solutions or strategies can be identified that may ‘turn the tide’. This study involves applied scientific research to improve knowledge on (ecological) functioning of the Scheldt Estuary by means of a chain of model developments by the project partners (INBO, UA and FHR)

Learning democracy in social work

In this contribution, we discuss the role of social work in processes of democracy. A key question in this discussion concerns the meaning of ‘the social’ in social work. This question has often been answered in a self-referential way, referring to a methodological identity of social work. This defines the educational role of social work as socialisation (be it socialisation into obedience or into an empowered citizen). However, the idea of democracy as ‘ongoing experiment’ and ‘beyond order’ challenges this methodological identity of social work. From the perspective of democracy as an ‘ongoing experiment’, the social is to be regarded as a platform for dissensus, for ongoing discussions on the relation between private and public issues in the light of human rights and social justice. Hence, the identity of social work cannot be defined in a methodological way; social work is a complex of (institutionalized) welfare practices, to be studied on their underlying views on the ‘social’ as a political and educational concept, and on the way they influence the situation of children, young people and adults in society

Incidence, Predictors, and Significance of Abnormal Cardiac Enzyme Rise in Patients Treated With Bypass Surgery in the Arterial Revascularization Therapies Study (ARTS)

BACKGROUND: Although it has been suggested that elevation of CK-MB after percutaneous coronary intervention is associated with adverse clinical outcomes, limited data are available in the setting of coronary bypass grafting. The aim of the present study was to determine the incidence, predictors, and prognostic significance of CK-MB elevation following multivessel coronary bypass grafting (CABG). METHODS AND RESULTS: The population comprises 496 patients with multivessel coronary disease assigned to CABG in the Arterial Revascularization Therapies Study (ARTS). CK-MB was prospectively measured at 6, 12, and 18 hours after the procedure. Thirty-day and 1-year clinical follow-up were performed. Abnormal CK-MB elevation occurred in 61.9% of the patients. Patients with increased cardiac-enzyme levels after CABG were at increased risk of both death and repeat myocardial infarction within the first 30 days (P=0.001). CK-MB elevation was also independently related to late adverse outcome (P=0.009, OR=0.64). CONCLUSIONS: Increased concentrations of CK-MB, which are often dismissed as inconsequential in the setting of multivessel CABG, appear to occur very frequently and are associated with a significant increase in both repeat myocardial infarction and death beyond the immediate perioperative period

Nanopatterned Self-Assembled Monolayers by Using Diblock Copolymer Micelles as Nanometer-Scale Adsorption and Etch Masks

Nanopatterned self-assembled monolayers (SAMs) are obtained from a simple, straight-forward procedure by using masks derived from monolayers of block copolymer micelles. The nanopatterned SAMs consist of regularly spaced circular hydrophilic areas with diams. of approx. 60 nm on a continuous hydrophopic background or vice versa. The surfaces are shown to be excellent tools for the prepn. of arrays of nanocrystal

Effect of Puumala hantavirus infection on human umbilical vein endothelial cell hemostatic function : Platelet interactions, increased tissue factor expression and fibrinolysis regulator release

Peer reviewe

Spatio-temporal Models of Lymphangiogenesis in Wound Healing

Several studies suggest that one possible cause of impaired wound healing is failed or insufficient lymphangiogenesis, that is the formation of new lymphatic capillaries. Although many mathematical models have been developed to describe the formation of blood capillaries (angiogenesis), very few have been proposed for the regeneration of the lymphatic network. Lymphangiogenesis is a markedly different process from angiogenesis, occurring at different times and in response to different chemical stimuli. Two main hypotheses have been proposed: 1) lymphatic capillaries sprout from existing interrupted ones at the edge of the wound in analogy to the blood angiogenesis case; 2) lymphatic endothelial cells first pool in the wound region following the lymph flow and then, once sufficiently populated, start to form a network. Here we present two PDE models describing lymphangiogenesis according to these two different hypotheses. Further, we include the effect of advection due to interstitial flow and lymph flow coming from open capillaries. The variables represent different cell densities and growth factor concentrations, and where possible the parameters are estimated from biological data. The models are then solved numerically and the results are compared with the available biological literature.Comment: 29 pages, 9 Figures, 6 Tables (39 figure files in total