Small-world networks, distributed hash tables and the e-resource discovery problem

Resource discovery is one of the most important underpinning problems behind producing a scalable, robust and efficient global infrastructure for e-Science. A number of approaches to the resource discovery and management problem have been made in various computational grid environments and prototypes over the last decade. Computational resources and services in modern grid and cloud environments can be modelled as an overlay network superposed on the physical network structure of the Internet and World Wide Web. We discuss some of the main approaches to resource discovery in the context of the general properties of such an overlay network. We present some performance data and predicted properties based on algorithmic approaches such as distributed hash table resource discovery and management. We describe a prototype system and use its model to explore some of the known key graph aspects of the global resource overlay network - including small-world and scale-free properties

Mixing multi-core CPUs and GPUs for scientific simulation software

Recent technological and economic developments have led to widespread availability of multi-core CPUs and specialist accelerator processors such as graphical processing units (GPUs). The accelerated computational performance possible from these devices can be very high for some applications paradigms. Software languages and systems such as NVIDIA's CUDA and Khronos consortium's open compute language (OpenCL) support a number of individual parallel application programming paradigms. To scale up the performance of some complex systems simulations, a hybrid of multi-core CPUs for coarse-grained parallelism and very many core GPUs for data parallelism is necessary. We describe our use of hybrid applica- tions using threading approaches and multi-core CPUs to control independent GPU devices. We present speed-up data and discuss multi-threading software issues for the applications level programmer and o er some suggested areas for language development and integration between coarse-grained and ne-grained multi-thread systems. We discuss results from three common simulation algorithmic areas including: partial di erential equations; graph cluster metric calculations and random number generation. We report on programming experiences and selected performance for these algorithms on: single and multiple GPUs; multi-core CPUs; a CellBE; and using OpenCL. We discuss programmer usability issues and the outlook and trends in multi-core programming for scienti c applications developers

Kants Ethik: Verwerfen oder Retten? Ein pragmatischer Vorschlag

Unter Kants vielfältigen Hinterlassenschaften an die Gegenwart ist seine Ethik, neben seiner Friedenspolitik, die heute vielleicht lebendigste. Die sich abzeichnenden Möglichkeiten von Humangentechnik und Gentechnologie motivieren auch zur Suche nach Grenzen des Verfügbaren im Menschen. In striktem Gegensatz zu allem Nutzendenken verspricht Kants Vernunftethik Auswege aus dieser zwiespältigen Situation

Auf der Suche nach dem Blick von Nirgendwo

Buchkritik über: Gottfried Seebass: Handlung und Freiheit. Philosophische Aufsätze. Mohr Siebeck Verlag, Tübingen 2006, 411 S. (= a). Gottfried Seebass: Willensfreiheit und Determinismus. Band 1: Die Bedeutung des Willensfreiheitsproblems. Akademie Verlag, Berlin 2007, 236 S. (= b

Hat die Philosophie noch eine Einheit?

Today philosophy falls apart into a "theoretical” and a "practical” sub-discipline, a situation to the detriment of both. On the back of a sketch of three stages of Western philosophy a diagnosis is made as to the practical origin of the theoretical/practical split, which also already contains within it the clue for a therapy. Both parts of philosophy could be set on a convergent path by recognizing two practical conflicts underlying philosophical problems: the biographical conflict of accepting the world and the social conflict of accepting others. A non-reductivist study of these conflicts might mitigate the present alienation within philosoph

What makes bodies beautiful

Health and beauty are the most important physical ideals. This paper seeks to compare and contrast these ideals, based on a value theory of human abilities. Health is comprehended as a potential ability to act grounded in bodily functions. Beauty is explained as a symbolising reference to happiness, physical beauty as a combination of organic orientation to purpose and virtuous orientation to action. Physical beauty is the implicit symbolic expression of mental and physical health. This teleological theory is tested and exemplified using current stereotypes such as youthfulness, slimness and shapelines