On the uniqueness of the equation for state-vector collapse

The linearity of quantum mechanics leads, under the assumption that the wave function offers a complete description of reality, to grotesque situations famously known as Schroedinger's cat. Ways out are either adding elements of reality or replacing the linear evolution by a nonlinear one. Models of spontaneous wave function collapses took the latter path. The way such models are constructed leaves the question, whether such models are in some sense unique, i.e. whether the nonlinear equations replacing Schroedinger's equation, are uniquely determined as collapse equations. Various people worked on identifying the class of nonlinear modifications of the Schroedinger equation, compatible with general physical requirements. Here we identify the most general class of continuous wavefunction evolutions under the assumption of no-faster-than-light signalling.Comment: 7 pages, LaTeX. Major changes performe

Using Stories to Enhance and Simplify Computer Simulations for Teaching

Computer-based simulations are a valuable teaching tool because they permit a learner to explore a phenomenon on his o w n and to learn from his mistakes. T w o factors, however, limit the use of computer simulations in teaching: good simulations are hard to build and learners can flounder with just a simulation. W e have built HeRMiT^, a case-based tutor that integrates a simulation with a library of videotaped stories. The stories make up for any lack of depth or fidelity in the simulation by facilitating the generalization and application of underlying principles

Berufliche Integration Behinderter in der Krise. Zur Wirksamkeit arbeitsmarktpolitischer Instrumente bei struktureller Unterbeschäftigung

"Mit der Aktivierung der Behindertenpolitik Ende der sechziger Jahre ist das Ziel der beruflichen Rehabilitation neu gewichtet worden. Damit wurde der Tatsache Rechnung getragen, daß die qualitative Verbesserung von Lebenschancen unmittelbar mit der Partizipation am Arbeitsmarkt zusammenhängt. Trotz einer solchen Aktivierung der Politik verschlechtert sich die Arbeitsmarktlage von Behinderten und Leistungsgeminderten seit Beginn der Beschäftigungskrise 1974/75 ständig. Die in den nächsten Jahren erwartbaren verschärften Beschäftigungsprobleme werden schon angesichts der finanziellen Engpässe öffentlicher Haushalte nicht durch eine Expansion der Ausgaben für eine berufliche Integrationspolitik angegangen werden können. Daher erscheint die Suche nach alternativen Lösungsmöglichkeiten dringend erforderlich. Der ... Beitrag versucht in einem ersten Schritt, die bislang angewandten Politikinstrumente zur Regulierung der Arbeitsmarktlage von Behinderten auf ihre Wirksamkeit hin zu überprüfen. In einem zweiten Schritt wird diskutiert, inwiefern die Etablierung von neuen Verhandlungssystemen, in denen die betroffenen Politikakteure auf lokaler Ebene kooperieren, eine höhere Wirksamkeit als die bekannten regulativen Politikinstrumente entfalten können. Abschließend werden Möglichkeiten einer partiellen Revision des Ziels der beruflichen Integration analysiert."Behinderte - Integration, Arbeitsmarktpolitik - Effizienz, strukturelle Arbeitslosigkeit, Wirkungsforschung, berufliche Rehabilitation

Turnover of microbial lipids in the deep biosphere and growth of benthic archaeal populations

Deep subseafloor sediments host a microbial biosphere with unknown impact on global biogeochemical cycles. This study tests previous evidence based on microbial intact polar lipids (IPLs) as proxies of live biomass, suggesting that Archaea dominate the marine sedimentary biosphere: We devised a sensitive radiotracer assay to measure the decay rate of ([C-14]glucosyl)-diphytanylglyceroldiether (GlcDGD) as an analog of archaeal IPLs in continental margin sediments. The degradation kinetics were incorporated in model simulations that constrained the fossil fraction of subseafloor IPLs and rates of archaeal turnover. Simulating the top 1 km in a generic continental margin sediment column, we estimated degradation rate constants of GlcDGD being one to two orders of magnitude lower than those of bacterial IPLs, with half-lives of GlcDGD increasing with depth to 310 ky. Given estimated microbial community turnover times of 1.6-73 ky in sediments deeper than 1 m, 50-96% of archaeal IPLs represent fossil signals. Consequently, previous lipid-based estimates of global subseafloor biomass probably are too high, and the widely observed dominance of archaeal IPLs does not rule out a deep biosphere dominated by Bacteria. Reverse modeling of existing concentration profiles suggest that archaeal IPL synthesis rates decline from around 1,000 pg.mL(-1) sediment.y(-1) at the surface to 0.2 pg.mL(-1).y(-1) at 1 km depth, equivalent to production of 7 x 10(5) to 140 archaeal cells.mL(-1) sediment.y(-1), respectively. These constraints on microbial growth are an important step toward understanding the relationship between the deep biosphere and the carbon cycle

Early embryonic development, assisted reproductive technologies, and pluripotent stem cell biology in domestic mammals

Over many decades assisted reproductive technologies, including artificial insemination, embryo transfer, in vitro production (IVP) of embryos, cloning by somatic cell nuclear transfer (SCNT), and stem cell culture, have been developed with the aim of refining breeding strategies for improved production and health in animal husbandry. More recently, biomedical applications of these technologies, in particular, SCNT and stem cell culture, have been pursued in domestic mammals in order to create models for human disease and therapy. The following review focuses on presenting important aspects of pre-implantation development in cattle, pigs, horses, and dogs. Biological aspects and impact of assisted reproductive technologies including IVP, SCNT, and culture of pluripotent stem cells are also addressed. © 2013 Elsevier Ltd