The Use of Radar Imagery to Assess the Bottom Topography of Shallow Seas

Under favourable conditions features of the bottom topography of shallow seas are visible in radar images, which are nowadays obtained from satellites on a routine basis. A Bathymetry Assessment System (BAS) was developed to use these images in order to produce depth maps. This paper describes the principles behind the system, indicates for what type of applications it might be useful, notes on the accuracy and gives an example of an application

The One-Tier Board in the Changing and Converging World of Corporate Governance: A comparative study of boards in the UK, the US and the Netherlands

Binnen het bestuur en de Raad van Commissarissen (RvC) van een onderneming is jaarlijks overleg nodig over de omgang met elkaar. Dit verbetert de informatieverstrekking aan de RvC, die zo meer en eerder betrokken is bij besluitvorming over strategie. Op 6 juni 2011 is de One-Tier Board Wet aangenomen, die inhoudt dat Nederlandse organisaties die van oudsher een zogenaamde Two-Tier Board hebben, ook een One-Tier mogen voeren naar het model van Engeland en Amerika. De geschiedenis en de cultuur van de bestuursmodellen zijn in elk land verschillend. De samenstelling, rol, taken en aansprakelijkheid van het besturen verschillen evenzeer. Er zijn in de laatste twintig jaar in de drie landen veel veranderingen geweest die leiden tot convergentie maar er blijven ook verschillen, ook tussen Engeland en Amerika. Calkoen constateert dat Nederlandse commissarissen op enige uitzonderingen na, niet sterk betrokken zijn bij de ontwikkeling van de strategie. Dat is voorbehouden aan het bestuur. De commissarissen zijn beperkt tot toezicht en hebben een veto op bepaalde besluiten. Dit betekent dat de Nederlandse commissarissen een gebrek hebben aan vroege informatie, informatie van de werkvloer van de onderneming en aan gesprekken met lager management, zoals Engelse en Amerikaanse niet-uitvoerende bestuurders dat wel hebben. De niet-uitvoerende bestuurders in een One-Tier bestuur krijgen eerdere en betere informatie, hebben meer tijd voor discussie en zijn betrokken bij de besluit- en strategievorming. Zij weten daardoor meer van de onderneming en van wat er speelt bij de managers. Zij ervaren ook dat het nuttig is om jaarlijks overleg te hebben over de manier van omgang met elkaar. Dit zijn praktische voordelen van een One-Tier bestuursmodel. Het voordeel van het Two-Tier systeem is dat de RvC met haar onafhankelijkheid een onderdeel is van de Nederlandse bestuurscultuur, waarmee men met beleid dient om te gaan. Calkoen beveelt aan binnen een Two-Tier bestuursmodel, te beginnen met het invoeren van de praktische voordelen van een One-Tier systeem. Zo kan men geleidelijk verbeteren en eventueel later kiezen voor een One-Tier bestuur, waarbij de niet-uitvoerende bestuurders werkelijk meebeslissen. Op deze manier biedt de One-Tier Board Wet kansen op verbeteringen en keuzes

Moose (Alces alces) browsing patterns in recently planted clear-cut areas in relation to predation risk of the gray wolf (Canis lupus) in Sweden

The aim of this study was to test whether behaviorally mediated effects of gray wolf (Canis lupus) presence were visible in terms of browsing intensity by moose (Alces alces) on tree saplings in recently planted clear-cut areas in Sweden. The study involved two different spatial scales; the clear-cut scale and tree scale. At the clear-cut scale the influence of wolf predation risk, tree density and tree height on moose browsing intensity was evaluated. At the individual tree scale, the factor distance to the nearest forest edge was also included. Browsing intensity was measured as apical shoot browsing and lateral shoot browsing in 24 different recently planted clear-cuts. Due to differences in preference between tree species and qualitative differences between plant parts, the same analyses were conducted for the five main tree species and for apical and lateral shoot browsing separately. Based on pellet group counts, moose is most likely the main browser in this study. Further, I found that both tree density and tree height were lower in the wolf core areas, suggesting multicollinearity between wolf utilization, tree density and tree height at the clear-cut scale, the effect of these factors could not be separated in the multivariate models. At the clear-cut scale browsing intensity decreased with tree density. At the tree scale, although wolf utilization was an important factor explaining the variation in browsing intensity, the browsing probability decreased with tree height. Overall, this suggests that moose foraging and thus its browsing intensity was more influenced by tree density and tree height than predation risk by wolves. It also seemed that moose browse through a clear-cut area irrespectively of distance to the closest forest edge

Web tool for energy policy decision-making through geo-localized LCA models: A focus on offshore wind farms in Northern Europe

International audienceEnvironmental performances of electricity generation, expressed as environmental impacts per kWh of electricity produced, depend strongly on technical, methodological and geographical parameters. When considering the global environmental performances of renewable energies, a geo-dependent life cycle assessment (LCA) taking into account geographical issues is of high interest. To illustrate this issue, a web map service enabling "geolocalized life cycle assessment" of offshore wind farms for different configurations has been developed. Based on a modular LCA model and on collaborative works made within the framework of the FP7 co-funded project EnerGEO, the developed tool should help decision makers in assessing the global environmental impacts caused by an offshore wind farm in Northern Europe

Atrioventricular septal defect : advanced imaging from early development to long-term follow-up

The aim of this thesis is to review the current knowledge on atrioventricular septal defect (AVSD) (Part 1), to study the pathogenesis of AVSD (Part 2) and finally to analyze cardiac outcome long-term after AVSD correction (Part 3). Studies are performed with novel imaging techniques. In part 2 it is made plausible that AVSD is a sliding scale and that patients with Down syndrome without AVSD also have abnormalities of the membranous septum and atrioventricular valves. High frequency ultrasound in mouse embryos shows to be a promising technique to study cardiovascular flow in early stages of heart development. In a mouse model with disturbed VEGF signalling, the heart rate is reduced and the sinoatrial node develops abnormally. Finally, in part 3 of this thesis, 4DFlow MRI data reveals that patients with an abnormal left atrioventricular valve (LAVV) after AVSD correction have aberrant intra-cardiac flow patterns. During diastole the inflow into the left ventricle is directed more towards the lateral wall, more towards the apex and vortex formation is abnormal. During systole the dynamic and eccentric regurgitation of the LAVV disturbs the normal recirculating flow patterns in the left atrium.4DFlow MRI can be used to reliably quantify flow over the LAVV.UBL - phd migration 201

Mesenchymal stromal cells in pediatric disease : pathophysiology and treatment

Mesenchymal stromal cells (MSCs) support hematopoiesis in the bone marrow, are involved in tissue repair and modulate immune responses. The aim of this thesis is to study the function of MSC derived from children suffering from childhood malignant diseases (Myelodysplastic syndrome (MDS) and Juvenile myelomonocytic leukemia (JMML)) or from systemic juvenile idiopathic arthritis. The MSCs form children with MDS and JMML have an altered RNA expression profile with marked differences in e.g. immunomodulatory genes. These alterations were reversible after hematopoietic stem cell transplantation (HSCT). Our data support the hypothesis that malignant cells profit from the altered bone-marrow microenvironment by escaping the immune defense and occupying the hematopoietic niche. In the future, these mechanisms will be possible targets for therapy. In addition, the impact of MSCs on virus-specific immune recovery and acute graft-versus-host disease (aGvHD) after pediatric allogeneic HSCT has been investigated. We show in the studies described that biopsies of the intestinal tract are essential at diagnosis but also to monitor treatment after experimental therapy. Our data support early treatment with MSCs in steroid refractory aGvHD irrespective of ongoing viral reactivations. These data were used for the design of a multi-center randomized controlled trial with MSCs.KiKa, Stichting Kinderen KankervrijUBL - phd migration 201

Mapping of sea bottom topography

Under suitable conditions the bottom topography of shallow seas is visible in remote sensing radar imagery. Two experiments were performed to establish which remote sensing technique or combination yields optimal imaging of bottom topography and which hydro-meteorological conditions are favorable. A further goal is to gain experience with these techniques. Two experiments were performed over an area in the North Sea near the measuring platform Meetpost Noordwijk (MPN). The bottom topography in the test area is dominated by sand waves. The crests of the sand waves are perpendicular to the coast line and the dominating (tidal-)current direction. A 4x4 sq km wide section of the test area was studied in more detail. The first experiment was undertaken on 16 Aug. 1989. During the experiment the following remote sensing instruments were used: Landsat-Thematic Mapper, and NASA/JPL Airborne Imaging Radar (AIR). The hydro-meteorological conditions; current, wind, wave, and air and water temperature were monitored by MPN, a ship of Rijkswaterstaat (the OCTANS), and a pitch-and-roll WAVEC-buoy. The second experiment took place on 12 July 1992. During this experiment data were collected with the NASA/JPL polarimetric synthetic aperture radar (SAR), and a five-band helicopter-borne scatterometer. Again the hydro-meteorological conditions were monitored at MPN and the OCTANS. Furthermore, interferometric radar data were collected

Energy transfer in LHCII monomers at 77K studied by sub-picosecond transient absorption spectroscopy.

Energy transfer from chlorophyll b (Chl b) to chlorophyll a (Chl a) in monomeric preparations of light-harvesting complex II (LHCII) from spinach was studied at 77 K using pump-probe experiments. Sub-picosecond excitation pulses centered at 650 nm were used to excite preferentially Chl b and difference absorption spectra were detected from 630 to 700 nm. Two distinct Chl b to Chl a transfer times, ~200 fs and 3 ps, were found. A clearly distinguishable energy transfer process between Chl a molecules occurred with a time constant of 18 ps. The LHCII monomer data are compared to previously obtained LHCII trimer data, and both data sets are fitted simultaneously using a global analysis fitting routine. Both sets could be described with the following time constants: 140 fs, 600 fs, 8 ps, 20 ps, and 2.9 ns. In both monomers and trimers 50% of the Chl b to Chl a transfer is ultrafast (<200 fs). However, for monomers this transfer occurs to Chl a molecules that absorb significantly more toward shorter wavelengths than for trimers. Part of the transfer from Chl b to Chl a that occurs with a time constant of 600 fs in trimers is slowed down to several picoseconds in monomers. However, it is argued that observed differences between monomers and trimers should be ascribed to the loss of some Chl a upon monomerization or a shift of the absorption maximum of one or several Chl a molecules. It is concluded that Chl b to Chl a transfer occurs only within monomeric subunits of the trimers and not between different subunits

Xanthophylls in light-harvesting complex II of higher plants: light harvesting and triplet quenching

A spectral and functional assignment of the xanthophylls in monomeric and trimeric light-harvesting complex II of green plants has been obtained using HPLC analysis of the pigment composition, laser-flash induced triplet- minus-singlet, fluorescence excitation, and absorption spectra. It is shown that violaxanthin is not present in monomeric preparations, that it has most likely a red-most absorption maximum at 510 nm in the trimeric complex, and that it is involved in both light-harvesting and Chl-triplet quenching. Two xanthophylls (per monomer) have an absorption maximum at 494 nm. These play a major role in both singlet and triplet transfer. These two are most probably the two xanthophylls resolved in the crystal structure, tentatively assigned to lutein, that are close to several chlorophyll molecules [Kuhlbrandt, W., Wang, N., D., and Fujiyoshi, Y. (1994) Nature 367, 614-621]. A last xanthophyll contribution, with an absorption maximum at 486 nm, does not seem to play a significant role in light-harvesting or in Chl-triplet quenching. On the basis of the assumption that the two structurally resolved xanthophylls are lutein, this 486 nm absorbing xanthophyll should be neoxanthin. The measurements demonstrate that violaxanthin is connected to at least one chlorophyll a with an absorption maximum near 670 nm, whereas the xanthophylls absorbing at 494 nm are connected to at least one chlorophyll a with a peak near 675 nm