It's all in the game

De computer game industrie is in omvang de afgelopen jaren de filmindustrie gepasseerd. Het ontwikkelen van een computer game kost tegenwoordig vele miljoenen. Teams van tientallen programmeurs, animators, grafisch ontwerpers en geluidstechnici werken er vele jaren aan. Toch werd er tot recent in het onderwijs vrijwel geen aandacht aan besteed. Dit begint nu te veranderen. Aan een aantal universiteiten in het buitenland worden vakken over computer game ontwerp opgezet. Ook zijn er een aantal (commerciële) onderwijsinstellingen ontstaan die zich primair op game design richten. In Nederland kan men sinds twee jaar de opleiding Design for Virtual Theatre and Games volgen aan de hogeschool voor de kunsten in Utrecht. Deze opleiding richt zich sterk op de artistieke aspecten van game design. Aan de universiteit Utrecht wordt sinds afgelopen jaar binnen de opleiding Informatica door mij een vak Game Design verzorgd dat meer ingaat op de technische aspecten van het onderwerp. In dit artikel wil ik schetsen hoe dat vak is opgezet en de ervaringen van het eerste jaar geven. Hopelijk inspireert dit anderen om binnen het informatica-onderwijs op verschillende niveaus aandacht aan game design te geven

The Effect of Local Heat and Cold Therapy on the Intraarticular and Skin Surface Temperature of the Knee

Objective. To evaluate the effects of local application of ice chips, ligno-paraffin, short-wave diathermy, and nitrogen-cold air on skin and intraarticular temperature. \ud Methods. Forty-two healthy subjects were divided into 4 treatment groups. A temperature probe was inserted into the knee joint cavity and another placed on the overlying skin, and changes in temperature over 3 hours, by treatment group, were recorded. \ud Results. The mean skin surface temperature dropped from 27.9°C to 11.5°C after application of ice chips, and from 28.8°C to 13.8°C after application of cold air. The mean intraarticular temperature decreased from 31.9°C to 22.5°C and from 32.9°C to 28.8°C, respectively, after these 2 treatments. Short-wave diathermy increased skin temperature by 2.4°C; intraarticular temperature was increased only 1.4°C by short-wave diathermy. Treatment with ligno-paraffin increased the skin surface temperature 8.9°C; the temperature in the joint cavity was increased 3.5°C. \ud Conclusion. The use of short-wave diathermy and superficial heat packs in the treatment of patients with arthritis may potentially cause harm by increasing intraarticular temperature. This may have major implications regarding treatment policy for patients with arthritis

Climatic and human influences on water resources in low atolls

Low, small islands have water supply problems amongst the most critical in the world. Fresh groundwater, the major source of water in many atolls, is vulnerable to natural and human-induced changes. Storm surges, droughts and over-extraction cause seawater intrusion. Settlements and agricultural activities can rapidly pollute shallow groundwaters. Limited land areas restrict freshwater quantities, which are especially vulnerable during frequent ENSO-related droughts. Demand for freshwater is increasing due to population growth and urbanisation. Water use for traditional crops often competes with water supplies for communities. This paper analyses the impact of frequent severe droughts on the quality and quantity of fresh groundwater in a low, atoll, Tarawa, in the Republic of Kiribati. We also examine the impacts of groundwater harvesting on traditional subsistence crops such as coconuts and of landuse on water quality. Strategies for reducing risks from climate variations and human impacts and increasing resilience are discussed. (Résumé d'auteur

Incremental and Decremental Maintenance of Planar Width

We present an algorithm for maintaining the width of a planar point set dynamically, as points are inserted or deleted. Our algorithm takes time O(kn^epsilon) per update, where k is the amount of change the update causes in the convex hull, n is the number of points in the set, and epsilon is any arbitrarily small constant. For incremental or decremental update sequences, the amortized time per update is O(n^epsilon).Comment: 7 pages; 2 figures. A preliminary version of this paper was presented at the 10th ACM/SIAM Symp. Discrete Algorithms (SODA '99); this is the journal version, and will appear in J. Algorithm

Sustainable development of water resources in small island nations of the pacific

This paper uses examples from the Pacific to discuss sustainable water management in small islands. Population centres in small islands have water supply problems that are amongst the most critical in the world. Limited land areas severely restrict surface water storages. Freshwater is extremely vulnerable to natural processes and human activities. Limited land areas also restrict freshwater quantities, particularly in frequent ENSO-related droughts. Demand for water is increasing due to both natural population growth and to growing urbanisation. There are few water professionals in many small island nations, policy and institutional frameworks are deficient and community participation in water management is minimal. Water use for agriculture competes with community water supplies. Limited resources and geographic isolation restrict the potential for irrigated crop exports so that reliance on aid is systemic. At the core of water management problems are land tenure and the conflict between the requirements of urbanised societies and the traditional values and rights of subsistence communities. Reforms of governance and the provision of knowledge to communities are critical. Long-term partnerships are needed which promote self-reliance. Multi Agent Systems offer potential for reducing conflicts over water. Regional organisations, able to foster self-support, can play a crucial role in developing island-adopted and owned solutions. (Résumé d'auteur

Metagenomic analysis shows the presence of bacteria related to free-living forms of sulfur-Oxidizing Chemolithoautotrophic Symbionts in the rhizosphere of the seagrass Zostera marina

Seagrasses play an important role as ecosystem engineers; they provide shelter to many animals and improve water quality by filtering out nutrients and by controlling pathogens. Moreover, their rhizosphere promotes a myriad of microbial interactions and processes, which are dominated by microorganisms involved in the sulfur cycle. This study provides a detailed insight into the metabolic sulfur pathways in the rhizobiome of the seagrass Zostera marina, a dominant seagrass species across the temperate northern hemisphere. Shotgun metagenomic sequencing revealed the relative dominance of Gamma- and Deltaproteobacteria, and comparative analysis of sulfur genes identified a higher abundance of genes related to sulfur oxidation than sulfate reduction. We retrieved four high-quality draft genomes that are closely related to the gill symbiont of the clam Solemya velum, which suggests the presence of putative free-living forms of symbiotic bacteria. These are potentially highly versatile chemolithoautotrophic bacteria, able to alternate their metabolism between parallel pathways of sulfide oxidation (via sqr and fcc), nitrate reduction (denitrification or DNRA) and carbon fixation (via CBB or TCA cycle), depending on the environmental availability of sulfide. Our results support the hypothesis that seagrass meadows might function as a source of symbionts for invertebrates that inhabit within or around seagrass meadows. While providing ideal conditions for the proliferation of these free-living forms of symbionts, seagrasses would benefit from their genetic versatility, which contributes to sulfide detoxification and ammonium production, the seagrasses' preferred nitrogen source.European Union ERC 322551 European Science Foundation ConGenOmics program 6349 Fundacao para a Ciencia e Tecnologia (FCT) SFRH/BPD/63/03/2009 SFRH/BPD/107878/2015info:eu-repo/semantics/publishedVersio

Locked and Unlocked Polygonal Chains in 3D

In this paper, we study movements of simple polygonal chains in 3D. We say that an open, simple polygonal chain can be straightened if it can be continuously reconfigured to a straight sequence of segments in such a manner that both the length of each link and the simplicity of the chain are maintained throughout the movement. The analogous concept for closed chains is convexification: reconfiguration to a planar convex polygon. Chains that cannot be straightened or convexified are called locked. While there are open chains in 3D that are locked, we show that if an open chain has a simple orthogonal projection onto some plane, it can be straightened. For closed chains, we show that there are unknotted but locked closed chains, and we provide an algorithm for convexifying a planar simple polygon in 3D with a polynomial number of moves.Comment: To appear in Proc. 10th ACM-SIAM Sympos. Discrete Algorithms, Jan. 199

On R-trees with low query complexity

The R-tree is a well-known bounding-volume hierarchy that is suitable for storing geometric data on secondary memory. Unfortu- nately, no good analysis of its query time exists. We describe a new algo- rithm to construct an R-tree for a set of planar objects that has provably good query complexity for point location queries and range queries with ranges of small width. For certain important special cases, our bounds are optimal. We also show how to update the structure dynamically, and we generalize our results to higher-dimensional spaces