14,081 research outputs found
A critical assessment of recent trends in Dutch industrial relations
Not availablelabour economics ;
Gas transport and separation with ceramic membranes. Part II: Synthesis and separation properties of microporous membranes
Non-supported microporous silica (amorphous) and titania thin films were made by the polymeric gel route. The titania system consisted of particles smaller than 5 nm. Reproducible modification of supported γ-alumina films with silica demands a strict control of every modification step. Silica films of 30–60 nm thickness on top of and presumably partly inside the γ-alumina film were realised. The permeabilities of helium and hydrogen through this film are activated, while the propylene permeability was below the detection limit. Separation factors of a H2---C3H6 mixture are larger than 200 at 200 °C with a flux of the preferentially hydrogen of 1.6 × 10−6 mol/m2-sec-Pa. The pores must be of molecular dimensions to realise this (< 1 nm diameter). Preliminary research shows that changes in the synthesis parameters result in higher activation energies and improved separation properties. The relation between synthesis, resulting microstructure and gas separation properties, however, is not yet fully understood
Importance of DTM accuracy, precision and acquisition technique for estimating contributing areas of post-fire erosion at the slope and catchment scale
Wildfires are a frequent phenomenon in Portugal, affecting over 300.000 ha in dry years like 2003 and 2005. Directly and/or indirectly, wildfires can strongly enhance the hydrological response and associated sediment losses and, thereby, negatively affect land-use sustainability as well as ecosystem functioning of downstream aquatic habitats. Therefore, the EROSFIRE projects aim at developing a GIS-tool for predicting soil erosion hazard following wildfire and post-fire land management practices. Assessment and modeling of runoff and soil erosion rates critically depends on accurate estimates of the contributing areas. In the case of catchments as well as unbounded erosion plots (arguably, the only practical solution for slope-scale measurements), delineation of contributing area requires a Digital Terrain Model (DTM) with an adequate resolution and accuracy. The DTM that was available for the Colmeal study area (Goís municipality, central Portugal) was that of the 1:25.000 topographic map produced by the Military Geographic Institute. Since this study area involves a rather small experimental catchment of roughly 10 ha and relatively short study slopes of less than 100 m long, two different data acquisition techniques were used to produce high-resolution and high-accuracy DTM. One is aerial photogrammetry, whilst the other is terrestrial laser scanning. To produce a DTM by photogrammetric means, a dedicated digital aerial photography mission was carried out. The images had a pixel size of 10 cm. Manual measurements permitted to measure breaklines and were complemented by automatic measurements. In this way, a DTM in a TIN format was produced. This was further converted to grid format using the ArcGIS software system. Signalized control points allowed obtaining the DTM in the same global reference system as that employed for terrestrial laser scanning. The terrestrial laser scanning was done using a Riegl LMS Z360I, stationed in 8 points within the area to provide a complete coverage. The resulting dense cloud of points was filtered – by the company carrying out the scanning mission - to remove the non-terrain points (in particular vegetation). Several grids of different sizes were produced (0.10 x 0.10, 0.20 x 0.20, 0.50 x 0.50, 1 x 1 and 2 x 2 m2). The proposed work will compare and analyze estimates of contribution areas that were obtained with the two above-mentioned data acquisition techniques and for different spatial resolutions. This will be done for selected slope-scale sediment fences as well as for the outlet of the experimental catchment. In addition, different algorithms available in ArcGIS for TIN-to-grid conversion will be compared, since preliminary results have suggested that these procedures produce markedly different results
The future of the welfare state : reflections on Rogernomics
In this paper we recognize that reforms of the welfare state can be necessary from an economic point of view. We stress, however, that these reforms also have important social and political dimensions. The social dimensions are conceptualised by using Hofstede''s cultural characteristics. The scores on each of these characteristics can be related to desired characteristics of the welfare state. In a similar way different political views are related to a desired concept of the welfare state. Since consensus is a necessary condition for a successful reform of the welfare state, the reforms should be consistent with the culture of a society and its dominant political view. We apply these insights to the reforms in New Zealand, since these are very radical in nature and have attracted a lot of attention. Hofstede''s scores are used to measure the culture of New Zealand and the political views are derived from election results. Using these measures, we find that the reforms in New Zealand are inconsistent with the culture and the dominant political views of that country. Therefore we expect that a further implementation of the reforms will run into trouble. In order to provide some back-ground, we describe the economic situation in New Zealand and compare it with that of Australia. Since the economic situation of New Zealand does not outperform that of Australia, the favourable developments in New Zealand are not an obvious consequence of the reforms, as it is sometimes claimed. Moreover, we find that income inequalities have increased sharply in New Zealand and that the lower and middle-class incomes did not increase since 1980.mathematical applications;
The CIARD RING, an infrastructure for interoperability of agricultural research information services
Creating integrated information services in agriculture giving access and adding value to information residing in distributed sources remains a major challenge.
In distributed architectures, value added services by definition interface several information sources / services. Therefore value added services cannot be built without an awareness of what others have done: which sources are available, how to tap into them, how to exploit their semantics.
The Coherence in Information for Agricultural Research for Development (CIARD) Routemap to Information Nodes and Gateways (RING) is a portal offering an interlinked registry of existing information services in agriculture.
The CIARD RING covers both information services and sources: in nowadays information architectures, the distinction between the two is very fluid. In the RING, the definition of "service" includes any form of providing information from one server instance (website, mail server, web services, XML archive...) to many clients (browsers, email clients, news readers, harvesters...)
The services registered in the RING are described in details and categorized according to criteria that are relevant to the use of the service and its interoperability. The RING categorizes and interlinks the featured services according to criteria such as: standards adopted, vocabulary used, technology used, protocols implemented, level of interoperability etc. In addition, it features detailed instructions on how the registered services can be "interoperated".
The vision is that the RING will become the common global technical platform for the community of agricultural information professionals for accessing, sharing and exchanging information through web services.
This paper describes how the RING provides an infrastructure for enhancing interoperability of information sources and thus paves the way towards better accessibility of information through value-added and better targeted services
Gas and surface diffusion in modified γ-alumina systems
The transport of pure gases through a microporous membrane is described. The alumina-based membrane (pores 2.5-4 nm) is suitable for Knudsen diffusion separation. To improve the separation factor, interaction with and mobility on the pore wall of one of the gases of a mixture is necessary. To introduce surface diffusion of oxygen and hydrogen, a γ-alumina membrane was impregnated with silver. If temperature and atmosphere are controlled carefully, finely dispersed silver up to 17% by weight can be introduced. At higher loads and under oxidizing conditions, particle growth occurs. In adsorption experiments, little oxygen adsorption on the silver-modified γ-alumina could be detected. This is due to a decrease in accessible surface area of the silver because of particle growth of silver under oxygen. The mobility of hydrogen on the surface was tested by counterdiffusion experiments, of which the theory is given. Hydrogen shows a considerable mobility on the surface at 293 K. At low pressures the flux ratio of hydrogen to nitrogen improved from 3.8 to 8.8. Magnesia was introduced into the γ-alumina membrane to enhance the adsorption and mobility of CO2. It is known that 30% of the CO2 transport on non-modified γ-alumina is surface diffusion. The highest achievable magnesia load was 2.2% by weight. Introduction of magnesia into the γ-alumina surface gives more strong base sites and fewer weak base sites. This results in stronger bonding of CO2 on the surface, but the amount adsorbed is comparable with the amount of CO2 adsorbed on non-modified γ-alumina. The contribution of surface diffusion to the total transport decreases with the introduction of magnesia, as is shown by counterdiffusion. The more strongly bonded CO2 is less mobile, resulting in a smaller surface flux
Effect of the Resolution and Accuracy of DTM produced with Aerial Photogrammetry and Terrestrial Laser Scanning on Slope- and Catchment-scale Erosion Assessment in a Recently Burnt Forest Area: a Case Study
Wildfires are a common phenomenon in Portugal, affecting on average 100.000 ha of rural areas per year and up to 400.000 ha in dramatic years like 2003 and 2005. Wildfires can strongly enhance the hydrological response and associated sediment losses in recently burnt forest catchments and, thereby, negatively affect land-use sustain- ability of the affected terrains as well as ecosystem functioning of downstream aquatic habitats. Therefore, the EROSFIRE-I and –II projects aim at developing a GIS-tool for predicting soil erosion hazard following wildfire and, ultimately, for assessing the implications of alternative post-fire land management practices.
Assessment of runoff and soil erosion rates critically depends on accurate estimates of the corresponding runoff areas. In the case of catchments as well as unbounded erosion plots (arguably, the only practical solution for slope-scale measurements), delineation of runoff area requires a Digital Terrain Model (DTM) with an adequate resolution and accuracy. The DTM that was available for the Colmeal study area, localized in the mountain range of Lousã, in the central part of Portugal, of EROSFIRE-II project is that of the 1:25.000 topographic map produced by the Military Geographic Institute. Since the Colmeal area involves a rather small experimental catchment of roughly 10 ha and relatively short study slopes of less than 100 m long, two different data acquisition techniques were used to produce high-resolution and high-accuracy DTM. One of the data acquisition techniques is aerial photogrammetry whilst the other is terrestrial laser scanning. In order to produce a DTM by photogrammetric means, a dedicated digital aerial photography mission was carried out. The images have a pixel size of 10 cm. Manual measurements permitted to measure breaklines and were complemented by automatic measurements. In this way, a DTM in a TIN format was produced. This was further converted to grid format using the ArcGIS software system. Signalized control points allowed obtaining the DTM in the same global reference system as that employed for terrestrial laser scanning. The terrestrial laser scanning was done using a Riegl LMS Z360I, stationed in 8 points within the area to provide a complete coverage. The resulting dense cloud of points was filtered – by the company carrying out the scanning mission - to remove the non-terrain points (in particular vegetation). Several grids of different sizes were produced (0.10 x 0.10, 0.20 x 0.20, 0.50 x 0.50, 1 x 1 and 2 x 2 m2).
This work will study the effect on runoff and erosion rates at the slope- and catchment-scale of DTM with differ- ent resolution, but produced with data collected with the same acquisition technique, and of DTM with the same resolution, but produced with data collected with the two different acquisition techniques. The study is being carried out in ArcGIS using DTM in a grid format. Preliminary results suggest that the conver- sion of TIN-to-grid in ArcGIS produces results that depend on the procedure being applied. Therefore, the different algorithms available at ArcGIS for TIN-to-grid conversion are currently being tested, using an artificially produced DTM. This testing includes various interpolation techniques for grid generation, and will be extended to different algorithms for computation of drainage flow direction
Muon localization site in U(Pt,Pd)3
The angular and temperature (10-250 K) variation of the Knight shift of
single-crystalline U(Pt0.95Pd0.05)3 has been measured in transverse field
(B=0.6 T) mSR experiments. By analysing the temperature variation of the Knight
shift with a modified Curie-Weiss expression the muon localization site in this
hexagonal material is determined at (0,0,0).Comment: 12 pages (including 4 figures); postscript file; Proc. 8th Int. Conf.
on Muon Spin Rotation, Relaxation and Resonance (Aug.30-Sept.3, Les
Diablerets); 2nd version with minor correction
Location of catalase in crystalline peroxisomes of methanol-grown Hansenula polymorpha
We have studied the intraperoxisomal location of catalase in peroxisomes of methanol-grown Hansenula polymorpha by (immuno)cytochemical means. In completely crystalline peroxisomes, in which the crystalline matrix is composed of octameric alcohol oxidase (AO) molecules, most of the catalase protein is located in a narrow zone between the crystalloid and the peroxisomal membrane. In non-crystalline organelles the enzyme was present throughout the peroxisomal matrix. Other peroxisomal matrix enzymes studied for comparison, namely dihydroxyacetone synthase, amine oxidase and malate synthase, all were present throughout the AO crystalloid. The advantage of location of catalase at the edges of the AO crystalloids for growth of the organism on methanol is discussed.
Ceramic nanostructure materials, membranes and composite layers
Synthesis methods to obtain nanoscale materials will be briefly discussed with a focus on sol-gel methods. Three types of nanoscale composites (powders, membranes and ion implanted layers) will be discussed and exemplified with recent original research results. Ceramic membranes with a thickness of 1–10 μm consist of a packing of elementary particles with a size of 3–7 nm. The mean pore size is about 2.5–3 nm. The preparation routes are based on sol and sol-gel technologies. The pores can be modified by liquid as well as by gas deposition techniques. This leads to modification of the chemical character and the effective pore size and gives rise to microstructure elements well below the size of the pores (3 nm). The modification of ceramic surface layers with a thickness of 0.05–0.5 μm by ion implantation and annealing procedures yields amorphous or strongly supersatured metastable solid solutions of e.g. Fe2O3 (or TiO2) in zirconia-yttria solid solutions or of very finely dispersed metal particles in the ceramic surface layers. Particle sizes are of the order of 2–4 nm. Both types of structures have interesting transport, catalytic and mechanical properties
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