Some Analytic Solutions for Stochastic Reactor Models Based on the Joint Composition PDF

The stochastic reactor models Partially Stirred Reactor (PaSR) and Partially Stirred Plug Flow Reactor (PaSPFR) have been investigated. These models are based on a simplified joint composition PDF transport equation. Analytic solutions for five different Cauchy problems for the PDF transport equation as given by the stochastic reactor models are presented. In all cases, molecular mixing in the stochastic reactor models is described by the LMSE mixing model. The analytic solutions have been found by combining the method of characteristics with a set of ordinary differential equations for the statistical moments to account for the functional dependence of the coefficients in the corresponding PDF transport equation. For each case an example problem is discussed to illustrate the behavior of the analytic solution

Democracy, the armed forces and military deployment: the 'second social contract' is on the line

"The increasing number of troop deployments by democratic states after the end of the Cold War has subjected the 'second social contract' – the (in most cases unwritten) agreement regulating relations between society, government and the armed forces – to new stresses. The authors of this report set out to name the causes and subsequent dangers of this development, urging for future deployment decisions to be more thoroughly and carefully considered. If the democratic responsibility for military deployments is not taken seriously, the gap grows between the armed forces and civilian society." (author's abstract

Demokratie, Streitkräfte und militärische Einsätze: der "zweite Gesellschaftsvertrag" steht auf dem Spiel

"Der (ungeschriebene) 'zweite Gesellschaftsvertrag' regelt das besondere Verhältnis von Gesellschaft, Regierung und Streitkräften und legt ihre jeweiligen Pflichten und Ansprüche fest, damit Militär in der Demokratie funktionieren kann. Vor dem Hintergrund der 'Armee im Einsatz' ist dieser Vertrag zunehmend Spannungen ausgesetzt. Die Wehrstrukturreform weitet die Kapazität der Bundeswehr für Auslandseinsätze weiter aus und trägt damit dem Neuen Strategischen Konzept der NATO Rechnung. Dieses sieht humanitäre Interventionen, Peacebuilding oder Friedenserhaltung als gleichberechtigte Aufgaben neben der kollektiven Verteidigung. Parallel dazu hätte allerdings ein Procedere für eine gründliche Prüfung der Sinnhaftigkeit jedes Einsatzes festgelegt werden müssen. Denn da ihr Status als Soldatinnen und Soldaten es verlangt, ihre persönlichen Belange denen der Nation unterzuordnen, auf wichtige Grundrechte zu verzichten und letztendlich ihr Leben zu riskieren, haben Soldatinnen und Soldaten im Gegenzug Anspruch auf höchstmögliche Fürsorge und Unterstützung von Gesellschaft und Regierung. Das heißt, Soldatinnen und Soldaten dürften nur nach äußerst sorgfältiger Abwägung in einen Einsatz geschickt werden. Die Autoren weisen auf die Praxis nicht hinreichend begründeter Entsendeentscheidungen und die damit einhergehende Gefahr der Entfremdung von Gesellschaft, Politik und Armee hin und nehmen die Politik in die Pflicht. Denn weder militärtechnische Risikominderungen noch rhetorische oder psychologische Verdrängungen eignen sich als Kitt für ein aus den Fugen geratenes Verhältnis." (Autorenreferat

Auf dem Weg zu Global Zero? Die neue amerikanische Nuklearpolitik zwischen Anspruch und Wirklichkeit

"Präsident Obama hat sich ausdrücklich zum Ziel einer kernwaffenfreien Welt bekannt und seiner Ankündigung prompt Taten folgen lassen: Die neue Nukleardoktrin, der NSTART-Vertrag, das Plutoniumabkommen und die einseitigen Transparenzmaßnahmen sind lange vermisste erste Schritte. Aber leiten sie tatsächlich einen Paradigmenwechsel ein? Die vier Autoren unterziehen die Verträge und Maßnahmen einer kritischen Prüfung und bewerten ihre Zukunftsfähigkeit. Der weitere Erfolg von Obamas ehrgeizigem Vorhaben wird sich nicht zuletzt im amerikanischen Senat entscheiden. Viel wird davon abhängen, wie weit es Obama gelingen wird, moderate Konservative von seinem Kurs zu überzeugen. Diese haben für die Gefahren eines möglichen nuklearen Terrorismus durchaus ein offenes Ohr, befürchten aber den möglichen Sicherheitsverlust, wenn auf nukleare Abschreckung verzichtet wird. Obama versucht, diese Besorgnisse durch konventionelle Aufrüstung zu entkräften. Das ist riskant, passen doch nukleare Abrüstung und konventionelle Dominanz nicht zusammen. Zudem gibt es durch die Wirtschaftskrise kaum finanzielle Spielräume für ehrgeizige Aufrüstungsvorhaben. Der Bundesregierung empfehlen die Autoren, im Bündnis weiterhin auf den Abzug der substrategischen Nuklearwaffen aus Deutschland zu drängen, das heißt für Bedingungen einzutreten, die das Sicherheitsbedürfnis der osteuropäischen Partner ernst nehmen, aber auch Russland erlauben, die Rolle seiner substrategischen Waffen zu reduzieren. Das könnte zum Beispiel durch die Ratifizierung des angepassten KSE-Vertrags und den Verzicht auf eine weitere Osterweiterung der NATO geschehen." (Autorenreferat

Some analytic solutions for stochastic reactor models based on the joint composition PDF

The stochastic reactor models, partially stirred reactor (PaSR) and partially stirred plug flow reactor (PaSPFR) have been investigated. These models are based on a simplified joint composition PDF transport equation. Analytic solutions for five different Cauchy problems for the PDF transport equation as given by the stochastic reactor models are presented. In all cases, molecular mixing in the stochastic reactor models is described by the linear mean-square estimation (LMSE) mixing model for turbulent diffusion. The analytic solutions have been found by combining the method of characteristics with a set of ordinary differential equations for the statistical moments to account for the functional dependence of the coefficients in the corresponding PDF transport equation. For each case an example problem is discussed to illustrate the behaviour of the analytic solution

Determination of relative chlorophyll binding affinities in the major light-harvesting chlorophyll a/b complex

The major light-harvesting complex (LHCIIb) of photosystem H can be reconstituted in vitro from its recombinant apoprotein in the presence of a mixture of carotenoids and chlorophylls a and b. By varying the chlorophyll a/b ratio in the reconstitution mixture, the relative amounts of chlorophyll a and chlorophyll b bound to LHCIIb can be changed. We have analyzed the chlorophyll stoichiometry in recombinant wild type and mutant LHCIIb reconstituted at different chlorophyll a/b ratios in order to assess relative affinities of the chlorophyll-binding sites. This approach reveals five sites that exclusively bind chlorophyll b. Another site exhibits a slight preference of chlorophyll b over chlorophyll a. The remaining six sites are filled preferentially with chlorophyll a but also tolerate chlorophyll b when this is offered at a large excess. Three of these chlorophyll a-affine sites could be assigned to distinct positions defined by the three-dimensional LHCIIb structure. Exclusive chlorophyll b sites complemented by chlorophyll a sites that are selective only to a certain extent are consistent with the observation that chlorophyll b but not chlorophyll a is essential for reconstituting stable LHCIIb. These data offer an explanation why a rather constant chlorophyll a/b ratio is observed in native LHCIIb despite the apparent promiscuity of some binding sites

Design Of A Grinding Machine For Glasses

Modern grinding machines have a scanner and a grinding part. The aim of the problem is to compute and simulate the geometric control of the grinding machine depending of the results of the scan and of some parameters of the lens. The results and simulation are performed on characteristic forms such as rectangles and ellipses with different centers. 1 Introduction The report describes the general setup of the machine parts and the technical problems we had to deal with. We modelled the grinding of the shape of the lens and of a bevel on the edge of the lens. In general all glasses are made of one frame and two lenses with different strength. Because every customer who needs glasses wants to choose his individual frame and has individual eye-measures, lenses have to be grind precisely. Normally, lenses the optician buys from the manufacturer have the shape of a circle with optical center indicated by a crug. The optician has to grind the lenses so that they are symmetric and fit to the ..

Towards Virtual Hardware Prototyping for Generated Geometric Multigrid Solvers

Many applications in scientific computing require solving one or more partial differential equations (PDEs). For this task, solvers from the class of multigrid methods are known to be amongst the most efficient. An optimal implementation, however, is highly dependent on the specific problem as well as the target hardware. As energy efficiency is a big topic in today's computing centers, energy-efficient platforms such as ARM-based clusters are actively researched. In this work, we present a domain-specific approach, starting with the problem formulation in a domain-specific language (DSL), down to code generation targeting a variety of systems including embedded architectures. Furthermore, we present an approach to simulate embedded architectures to achieve an optimal hardware/software co-design, i.e., an optimal composition of software and hardware modifications. In this context, we use a virtual environment (OVP) that enables the adaptation of multicore models and their simulation in an efficient way. Our approach shows that execution time prediction for ARM-based platforms is possible and feasible but has to be enhanced with more detailed cache and memory models. We substantiate our claims by providing results for the performance prediction of geometric multigrid solvers generated by the ExaStencils framework

Dextran-coated superparamagnetic iron oxide nanoparticles for magnetic resonance imaging: evaluation of size-dependent imaging properties, storage stability and safety

Background: Rising criticism of currently available contrast agents for magnetic resonance imaging, either due to their side effects or limited possibilities in terms of functional imaging, evoked the need for safer and more versatile agents. We previously demonstrated the suitability of novel dextran-coated superparamagnetic iron oxide nanoparticles (SPIONDex) for biomedical applications in terms of safety and biocompatibility. Methods: In the present study, we investigated the size-dependent cross-linking process of these particles as well as the size dependency of their imaging properties. For the latter purpose, we adopted a simple and easy-to-perform experiment to estimate the relaxivity of the particles. Furthermore, we performed an extensive analysis of the particles’ storage stability under different temperature conditions, showing their superb stability and the lack of any signs of agglomeration or sedimentation during a 12 week period. Results: Independent of their size, SPIONDex displayed no irritation potential in a chick chorioallantoic membrane assay. Cell uptake studies of ultra-small (30 nm) SPIONDex confirmed their internalization by macrophages, but not by non-phagocytic cells. Additionally, complement activation-related pseudoallergy (CARPA) experiments in pigs treated with ultra-small SPIONDex indicated the absence of hypersensitivity reactions. Conclusion: These results emphasize the exceptional safety of SPIONDex, setting them apart from the existing SPION-based contrast agents and making them a very promising candidate for further clinical development