Determination of polynuclear aromatic compounds in composted municipal refuse and compost-amended soils by a simple clean-up procedure

3 pages, 1 figure, 2 tables, 21 references.A rapid and reproducible procedure suitable for the analysis of polycyclic aromatic compounds (PACs) in sludges and soil samples has been developed. The PACs are isolated by ultrasonic extraction with methyl chloride, redissolution of the crude extract in isooctane and clean-up of the PAC-containing fraction by chromatography on alumina micro-columns. After separation and quantitative determination of the various PACS by capillary gas chromatography/mass spectrometry, more than 50 PAC compounds which cover a wide range of concentrations were detected in the sludge samples. The most abundant compounds were mono-, di- and trimethyl derivatives of naphthalene, phenanthrene, fluorene, dibenzethiophene and naphthothiophene. No accumulation of PAC in an agricultural soil after an experiment of compost application over three years was observed.Peer Reviewe

Exploring the relationship between effort perception and poststroke fatigue

Objective: To test the hypothesis that poststroke fatigue, a chronic, pathologic fatigue condition, is driven by altered effort perception. / Methods: Fifty-eight nondepressed, mildly impaired stroke survivors with varying severity of fatigue completed the study. Self-reported fatigue (trait and state), perceived effort (PE; explicit and implicit), and motor performance were measured in a handgrip task. Trait fatigue was measured with the Fatigue Severity Scale-7 and Neurologic Fatigue Index. State fatigue was measured with a visual analog scale (VAS). Length of hold at target force, overshoot above target force, and force variability in handgrip task were measures of motor performance. PE was measured with a VAS (explicit PE) and line length estimation, a novel implicit measure of PE. / Results: Regression analysis showed that 11.6% of variance in trait fatigue was explained by implicit PE (R = 0.34; p = 0.012). Greater fatigue was related to longer length of hold at target force (R = 0.421, p < 0.001). A backward regression showed that length of hold explained explicit PE in the 20% force condition (R = 0.306, p = 0.021) and length of hold and overshoot above target force explained explicit PE in the 40% (R = 0.399, p = 0.014 and 0.004) force condition. In the 60% force condition, greater explicit PE was explained by higher force variability (R = 0.315, p = 0.017). None of the correlations were significant for state fatigue. / Conclusion: Trait fatigue, but not state fatigue, correlating with measures of PE and motor performance, may suggest that altered perception may lead to high fatigue mediated by changes in motor performance. This finding furthers our mechanistic understanding of poststroke fatigue

Loop integration results using numerical extrapolation for a non-scalar integral

Loop integration results have been obtained using numerical integration and extrapolation. An extrapolation to the limit is performed with respect to a parameter in the integrand which tends to zero. Results are given for a non-scalar four-point diagram. Extensions to accommodate loop integration by existing integration packages are also discussed. These include: using previously generated partitions of the domain and roundoff error guards.Comment: 4 pages, 3 figures, revised, contribution to ACAT03 (Dec. 2003

Gene expression profiling of Leishmania (Leishmania) donovani: overcoming technical variation and exploiting biological variation

Gene expression profiling is increasingly used in the field of infectious diseases for characterization of host, pathogen and the nature of their interaction. The purpose of this study was to develop a robust, standardized method for comparative expression profiling and molecular characterization of Leishmania donovani clinical isolates. The limitations and possibilities associated with expression profiling in intracellular amastigotes and promastigotes were assessed through a series of comparative experiments in which technical and biological parameters were scrutinized. On a technical level, our results show that it is essential to use parasite harvesting procedures that involve minimal disturbance of the parasite's environment in order to ‘freeze' gene expression levels instantly; this is particularly a delicate task for intracellular amastigotes and for specific ‘sensory' genes. On the biological level, we demonstrate that gene expression levels fluctuate during in vitro development of both intracellular amastigotes and promastigotes. We chose to use expression-curves rather than single, specific, time-point measurements to capture this biological variation. Intracellular amastigote protocols need further refinement, but we describe a first generation tool for high-throughput comparative molecular characterization of patients' isolates, based on the changing expression profiles of promastigotes during in vitro differentiatio

Interaction of river hydraulics and vegetation dynamics

The universities of Ghent and Antwerp are investigating the impact of the vegetation on hydraulic characteristics of the river Aa (Antwerp, Belgium) and the Bierbza river (Poland). In these areas the interaction between groundwater, surface water and vegetation will be studied.In a first phase of this multidisciplinary study, the influence of the vegetation on the flow resistance in the stretch is examinated. Introducing the effective roughness of the bottom and the banks of the river into hydraulic computations is not that easy, but important. Different expressions for the roughness coefficient are available, each with their own restrictions. Certainly when plants occur in the channel and reduce the flow area, determination of the roughness coefficient is difficult. Simultaneousley, flood forecasting and other impacts of changing water levels and flows, ask for an accurate hydraulic model. Modelling summer situations with winter data and vice versa imply problems.The roughness coefficient of the river, as used in the Manning formula, is influenced by the vegetation. Further more, the Manning coefficient is also linked to the water velocity and the discharge. The kind of correlation is determined by the vegetation type.Field measurements are carried out to collect data on discharge and stage and on the amount and variation of aquatic weed growth. Velocity measurements in multiple cross sections are performed with both, a hydrometric propeller and an electromagnetic device. Further more, leakage or seepage from the groundwater influences the water balance and has to be included. Several measurement campaigns on both rivers allow to determine the variation of the friction factor (Manning n) as a function of time, vegetation and distance and the important hydraulic parameters, and all the information can be related to each other.Following a seasonal cycle, flow resistance increases with plant growth in spring, reaches a maximum in early summer and then decreases slowly to the minimum in winter. Knowledge of the variation of the biomass as a function of time should lead to appropriate use of roughness coefficients in modelling surface flow in rivers

Flood routing in the river Aa using ’Femme’

The software ’Femme’, (a flexible environment for mathematically modelling the environment) is developed by the Netherlands Institute of Ecology (NIOO)(Soetaert et al., 2004) and is used for the modelling of ecological processes. Femme’s code is open source and works on a modular base. The implementation of a one dimensional hydrodynamic model into ’Femme’ to study the interaction between ecological processes and surface water flow as a driving force and the validation using field measurements is subject of this research. For example, the presence of macrophytes has an influence on the discharge by way of the entire roughness of the river, expressed by the Manning coefficient.River hydraulics is characterised by changing discharges and water levels due to rain fall, so studies have to take into account the non-permanent character of the flow. In a first phase, the river characteristics and the simplified Saint-Venant equations have been built into the model. The simplification to the parabolic and the kinematic equations allow a faster and easier solution. The parabolic model is known as the convection-diffusion equation and describes the translation, deformation and attenuation of a wave in open channels and is valid for stretches with mild slopes. The kinematic model doesn’t take into account the flattening of the wave and can only be applied in short stretches.Calculation results are presented by the variation of the discharge as a function of distance. Also the influence of the roughness coefficient is shown.The integrated study of ecological processes and surface water flow is situated in a multidisciplinary research were attention is paid to the interaction of groundwater, surface water and the ecological system in order to describe the transport of matter through river basins (Buis et al.,2005). An important study area is the river Aa near Poederlee (Belgium, Flanders, province of Antwerp), were discharge, grondwater and biomass measurements are carried out on a regular base, to perform studies in the field and to collect calibration data for the integrated hydraulics and ecology model

Nail surface topography and onychochronobiology.

Peer reviewe

Region-Specific Responses of Adductor Longus Muscle to Gravitational Load-Dependent Activity in Wistar Hannover Rats

Response of adductor longus (AL) muscle to gravitational unloading and reloading was studied. Male Wistar Hannover rats (5-wk old) were hindlimb-unloaded for 16 days with or without 16-day ambulation recovery. The electromyogram (EMG) activity in AL decreased after acute unloading, but that in the rostral region was even elevated during continuous unloading. The EMG levels in the caudal region gradually increased up to 6th day, but decreased again. Approximately 97% of fibers in the caudal region were pure type I at the beginning of experiment. Mean percentage of type I fibers in the rostral region was 61% and that of type I+II and II fiber was 14 and 25%, respectively. The percent type I fibers decreased and de novo appearance of type I+II was noted after unloading. But the fiber phenotype in caudal, not rostral and middle, region was normalized after 16-day ambulation. Pronounced atrophy after unloading and re-growth following ambulation was noted in type I fibers of the caudal region. Sarcomere length in the caudal region was passively shortened during unloading, but that in the rostral region was unchanged or even stretched slightly. Growth-associated increase of myonuclear number seen in the caudal region of control rats was inhibited by unloading. Number of mitotic active satellite cells decreased after unloading only in the caudal region. It was indicated that the responses of fiber properties in AL to unloading and reloading were closely related to the region-specific neural and mechanical activities, being the caudal region more responsive

Quantification of the groundwater-surface water interaction by analysing temperature gradients in the streambed of the Aa river, Belgium

The aim of this research is to gain better insight in the diverse physical and biological processes in margins, inundation areas and the hyporheic zone of water courses on a local scale. Data and results presented are from a multidisciplinary study on exchange processes in river ecosystems in which biologists, hydrologists, ecologists and engineers cooperate.Groundwater and eco-biochemical models are integrated in order to determine the exchange of water, dissolved compounds and particulate matter. Several of these processes occur simultaneously and result in feedback to other processes; hence most of the investigations aim to determine net rates of exchange. GIS is used for data management, while FEMME (Soetaert et al., 2002) serves as a platform for the integration of the different models such as MODFLOW, DAFLOW, Delft3D, and WetSpa.An innovative but cost-effective method for field investigation is the measurement of streambed temperatures profiles, which lead to a delineation and quantification of the groundwater discharge on a local scale. For the Aa River site in Belgium, a typical low land river system, combinations of longitudinal and cross-sectional measurements of temperature profiles have been conducted. Along a 1400 m long section, 5 vertical measurements of up to 80-100 cm deep into the river bottom have been performed bi-monthly between August 2004 and February 2007 at 14 measurement points and 5 cross-sections. With this information we assessed the vertical component of the groundwater flux and the spatial and temporal variability of the groundwater-surface water exchange.A streambed temperature survey does not lead directly to an estimation of the groundwater flux. Additional information, especially thermodynamic parameters of the soilwater matrix are necessary.The groundwater fluxes were calculated as point values at the measurement locations on basis of an analytical solution presented by Arriaga et al. (2006), and which is solved with the help of Microsoft Excel Solver and MATLAB. The fundamental heat flow equation was also introduced in a diagenetic model, setup in FEMME and used to compare with the Arriaga et al. (2006) solution. Interpolation of the point estimates results in net groundwater fluxes on the scale of the surveyed area. These results show discharge as well as recharge dependent on the location along the section and the season. The upper reach shows in general higher discharge rates and no change in direction of the groundwater flow, whereas the lower reach is characterized by lower flow rates and a change of direction of flow