Flow routing in mangrove forests: field data obtained in Trang, Thailand

Mangroves grow in the intertidal parts of sheltered tropical coastlines, facilitating coastal stabilization and wave attenuation. Mangroves are widely threatened nowadays, although past studies have indicated their contribution to coastal safety. Most of these studies were based on numerical modeling however and a proper database with field observations is lacking yet. This paper presents part of the results of an extensive field campaign in a mangrove area in Trang Province, Thailand. The study area covers the outer border of an estuarine mangrove creek catchment. Data have been collected on elevation, vegetation, water levels, flow directions and flow velocities throughout this study area. Due to the tough conditions in the field, developing a suitable method for data collection and processing has been a major challenge in this study. Analysis of the hydrodynamic data uncovers the change of flow directions and velocities throughout a mangrove creek catchment over one tidal cycle. In the initial stages of flooding and the final stages of ebbing, creeks supply water to the lower elevated parts of the mangroves. In between these stages, the entire forest bordering the estuary is flooded and flow directions are perpendicular to the forest fringe. Flow velocities within the creeks are still substantially higher than those within the forest, as the creeks also supply water to the back mangroves. These insights in flow routing are promising for the future analysis of sediment input and distribution in mangroves

Endocrine disruptors in the Scheldt estuary: distribution exposure and effects

The Scheldt Estuary is known as one of the more polluted estuaries in Europe (OSPAR, 2000). The major compartments of the estuary, i.e. water, suspended solids, sediments and biota, are all affected by common POPs (persistent organic pollutants). In the framework of the ENDIS-RISKS project these compartments were frequently sampled during the last four years and analysed for these POPs indicated as possible endocrine disruptors. As such, the concentration levels of 22 different polycyclic aromatic hydrocarbons (PAHs), 18 polybrominated diphenylethers (PBDEs), 5 organochlorine pesticides (OCPs), 16 polychlorinated biphenyls (PCBs) and 6 organotin compounds e.g. TBT were determined by the MUMM laboratory. Their distribution (speciation within different compartments), concentration and geographic distribution are assessed. For the biota compartment, mysids were selected as an indicator organism for this particular ecosystem. In these invertebrates, the highest levels ever found for TBT were noted, with concentrations of up to 2500µg.kg-1 on a dry weight basis (or approx. 100µg.kg-1 on a wet weight basis). In the same species, SPCB7 levels varying from 200 to 1400 µg.kg-1 on dry weight were noted. OCPs and PAHs concentrations varied from 5 to 100µg.kg-1dw. The geographic distribution - along the salinity gradient of the Scheldt Estuary - of the body burdens of these compounds in mysids are discussed. Finally, the observations were compared to internationally accepted ‘Ecotoxicological Assessment Criteria’ used to assess the potential adverse effects on the ecosystem

Endocrine disruptors in the Scheldt estuary (2)

The Scheldt Estuary is known as one of the more polluted estuaries in Europe (OSPAR, 2000). All major compartments of the estuary, i.e. water, suspended matter, sediments and biota, may be contaminated with chemicals such as polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and organotin compounds. In the framework of the ENDIS-RISKS project, the different compartments of the estuary were sampled during the last 2 years and the concentration levels of 22 different polycyclic aromatic hydrocarbons (PAHs), 18 polybrominated diphenylethers (PBDEs), 5 OCPs, 16 PCBs and 6 organotin compounds were determined. For the biota, mysids were selected as indicator organism for this particular ecosystem. In this group of organisms, the highest contaminant levels were found for TBT with concentrations of up to 2500µg/kg on a dry weight basis (or approx. 100µg/kg on a wet weight basis). With an ecotoxicological assessment criterium (EAC) - as established by OSPAR - of 2.4µg/kg on wet weight basis, the EAC is exceeded by a factor of 50 at some sampling stations. For the same species, the body concentrations of SPCB7 varyied from 200 to 1400µg/kg (dry weight), again exceeding the OSPAR-EAC by a factor of more than 100. OCPs and PAHs are found in quantities varying from 5 to 100µg/kg (dry weight) which is below the EAC, except for lindane (EAC 0.29µg/kg on wet weight basis)

The relationship between local scalp skin temperature and cutaneous perfusion during scalp cooling

Cooling the scalp during administration of chemotherapy can prevent hair loss. It reduces both skin blood flow and hair follicle temperature, thus affecting drug supply and drug effect in the hair follicle. The extent to which these mechanisms contribute to the hair preservative effect of scalp cooling remains unknown. The purpose of this study was to establish a relationship between local scalp skin temperature and cutaneous blood flow during scalp cooling. We measured skin temperature and cutaneous perfusion during a cooling and re-warming experiment. Experiments on a single subject showed that the measurements were reproducible and that the response was identical for the two positions that were measured. Inter-subject variability was investigated on nine subjects. We found that for the first 10 °C of cooling, perfusion of the scalp skin decreases to below 40%. Perfusion can be further reduced to below 30% by a few degrees more cooling, but a plateau is reached after that. We found that a generally accepted relation in thermal physiology between temperature and perfusion (i.e. Q10 relation) does not describe the data well, but we found an alternative relation that describes the average behavior significantly better

Body mass, body composition and sleeping metabolic rate before, during and after endurance training

Body mass, body composition and sleeping metabolic rate before, during and after endurance training. Westerterp KR, Meijer GA, Schoffelen P, Janssen EM. Department of Human Biology, University of Limburg, Maastricht, The Netherlands. Metabolic rate, more specifically resting metabolic rate (RMR) or sleeping metabolic rate (SMR), of an adult subject is usually expressed as a function of the fat-free mass (FFM). Chronic exercise is thought to increase FFM and thus to increase RMR and SMR. We determined body mass (BM), body composition, and SMR before, during, and after an endurance training programme without interfering with energy intake. The subjects were 11 women and 12 men, aged 37 (SD 3) years and body mass index 22.3 (SD 1.5) kg.m-2. The endurance training prepared subjects to run a half marathon competition after 44 weeks. The SMR was measured overnight in a respiration chamber. Body composition was measured by hydrostatic weighing. Measurements were performed at 0, 8, 20, 40, and 90 weeks after the start of the training. The BM had decreased from a mean value of 66.6 (SD 6.9) to 65.6 (SD 6.7) kg (P < 0.01), fat mass (FM) had decreased from 17.1 (SD 3.9) to 13.5 (SD 3.6) kg (P < 0.001), and FFM had increased from 49.5 (SD 7.3) to 52.2 (SD 7.6) kg (P < 0.001) at 40 weeks. Mean SMR before and after 40 weeks training was 6.5 (SD 0.7) and 6.2 (SD 0.6) MJ.day-1 (P < 0.05). The decrease in SMR was related to the decrease in BM (r = 0.62, P = 0.001). At 90 weeks, when most subjects had not trained for nearly a year, BM and SMR were not significantly different from the initial value while FM and FFM had not changed since week 40 of trainin

Diffusion enhancement in on/off ratchets

We show a diffusion enhancement of suspended polystyrene particles in an electrical on/off ratchet. The enhancement can be described by a simple master equation model. Furthermore, we find that the diffusion enhancement can be described by a general curve whose shape is only determined by the asymmetry of the ratchet repeat unit. The scaling of this curve can be explained from an analytical expression valid for small off-times. Finally, we demonstrate how the master equation model can be used to find the driving parameters for optimal particle separation. (C) 2013 American Institute of Physics

Removal of interleukin-1ß and tumor necrosis factor from human plasma by in vitro dialysis with polyacrylonitrile membranes

Contains fulltext : 4735.pdf (publisher's version ) (Open Access

The performance of organic electronic ratchets

Organic electronic ratchets rectify time-correlated external driving forces, giving output powers that can drive electronic circuitry. In this work their performance characteristics are investigated using numerical modeling and measurements. It is shown how the characteristic parameters of the time–varying asymmetric potential like length scales and amplitude, as well as the density and mobility of the charge carriers in the device influence the performance characteristics. Various ratchet efficiencies and their relations are discussed. With all settings close to optimum, a ratchet with charge displacement and power efficiencies close to 50% and 7% respectively is obtained