Cyclical bi-directional rotary actuator

A thermally powered rotary actuator is disclosed which is used for positioning a shaft in first and second positions which are disposed 180 deg apart. A pair of heat extensible springs are attached to the shaft and to the frame of the rotary actuator for selectively rotating the shaft from one of its two positions to the other position upon the application of heat to one of the heat extensible springs. The heat extensible springs are preferably constructed from the alloy 55-Nitinol. In the preferred embodiment, a detent mechanism is provided for locking the rotatable shaft in its two rotary positions

The MJS-77 magnetometer actuator

A two-position (0 deg and 180 deg) actuating mechanism (flipper) driven by alternately-heated wax motors (pellets) will be used to rotate the low field triaxial fluxgate magnetometer experiment on the 1977 Mariner Jupiter-Saturn spacecraft to its 0 deg and 180 deg positions. The magnetic field, power requirements, weight and volume of this device are very restrictive. The problems encountered in design and development of this mechanism are presented

A new concept for actuating space mechanisms

A two position (0 and 180 deg) actuating mechanism driven by two alternately heated opposing flat NITINOL springs is proposed for rotating the low field triaxial fluxgate magnetometer experiment on the 1977 Mariner Jupiter-Saturn spacecraft to its 0 deg and 180 deg positions. The magnetic field, power requirements, weight, and volume of this device are very restrictive. The problems encountered in design and development are presented

Transitions Induced by the Discreteness of Molecules in a Small Autocatalytic System

Autocatalytic reaction system with a small number of molecules is studied numerically by stochastic particle simulations. A novel state due to fluctuation and discreteness in molecular numbers is found, characterized as extinction of molecule species alternately in the autocatalytic reaction loop. Phase transition to this state with the change of the system size and flow is studied, while a single-molecule switch of the molecule distributions is reported. Relevance of the results to intracellular processes are briefly discussed.Comment: 5 pages, 4 figure

QCD and Yukawa corrections to single-top-quark production via q qbar -> t bbar

We calculate the O(alpha_s) and O(alpha_W m_t^2/M_W^2) corrections to the production of a single top quark via the weak process q qbar -> t bbar at the Fermilab Tevatron and the CERN Large Hadron Collider. An accurate calculation of the cross section is necessary in order to extract |V_tb| from experiment.Comment: LaTeX, 13 pages, replaced with version to appear in Phys. Rev.

Analysis of protrusion dynamics in amoeboid cell motility by means of regularized contour flows

Amoeboid cell motility is essential for a wide range of biological processes including wound healing, embryonic morphogenesis, and cancer metastasis. It relies on complex dynamical patterns of cell shape changes that pose long-standing challenges to mathematical modeling and raise a need for automated and reproducible approaches to extract quantitative morphological features from image sequences. Here, we introduce a theoretical framework and a computational method for obtaining smooth representations of the spatiotemporal contour dynamics from stacks of segmented microscopy images. Based on a Gaussian process regression we propose a one-parameter family of regularized contour flows that allows us to continuously track reference points (virtual markers) between successive cell contours. We use this approach to define a coordinate system on the moving cell boundary and to represent different local geometric quantities in this frame of reference. In particular, we introduce the local marker dispersion as a measure to identify localized membrane expansions and provide a fully automated way to extract the properties of such expansions, including their area and growth time. The methods are available as an open-source software package called AmoePy, a Python-based toolbox for analyzing amoeboid cell motility (based on time-lapse microscopy data), including a graphical user interface and detailed documentation. Due to the mathematical rigor of our framework, we envision it to be of use for the development of novel cell motility models. We mainly use experimental data of the social amoeba Dictyostelium discoideum to illustrate and validate our approach

Eine neue Methode zur in-situ Bestimmung von präferentiellen Fließwegen von Wasser im Boden

Böden zeigen in der Regel, auch auf sehr kleinem Raum, eine große Variabilität der hydraulischen Eigenschaften. Diese Eigenschaften, aber auch verschiedene Rand- und Anfangsbedingungen oder andere Bodeneigenschaften, können zu einer räumlich und zeitlich unterschiedlichen Verlagerung von Wasser und damit transportierten Stoffen führen (preferential flow). Diese präferentiellen Flüsse werden in der Regel nicht bei der Vorhersage des Wasser- und Stofftransportes berücksichtigt und können daher starke Abweichungen vom prognostizierten Wasser- und Stofftransport verursachen. Präferentielle Flüsse sind an eine bestimmte räumliche Skala gebunden. Auf der Profilskala auftretende präferentielle Flüsse können i. d. R. nicht an Stechzylinderproben im Labor gemessen werden. Deshalb wird eine neue Feldmethode vorgestellt, bei der präferentiell fließendes Wasser in-situ detektiert werden kann. Mit Hilfe einer Beregnungsanlage wird Wasser mit einer konstanten Rate auf einer Fläche von ca. 8 m2 verregnet. Wassergehalte und –spannungen werden mit TDR-Sonden und Tensiometern kurz unter der Bodenoberfläche gemessen. Die Einstellung des Fließgleichgewichtes kann an der Konstanz der Wassergehalte und –spannungen detektiert werden. Die gleichmäßige, kurzzeitige Verregnung eines Salztracers wird durch die Messung der elektrischen Leitfähigkeit des Bodenwassers mit den TDR-Sonden erfasst werden. Mit Hilfe dieses Pulses können lokale Fließgeschwindigkeiten und somit präferentielle Fließwege aufgezeigt werden. Untermauert werden die Ergebnisse des Beregnungsversuches mit weiteren in-Situ- und Labormessungen der hydraulischen Leitfähigkeit und Simulationsmodellen. Mit der vorgestellten Methode konnten präferenzielle Wasserflüsse im Boden auch bei unterschiedlichen Anfangs- und Randbedingung beobachtet werden und so zu einem besseren Prozessverständnis beitragen

Beyond multimorbidity:What can we learn from complexity science?

Multimorbidity - the occurrence of two or more long-term conditions in an individual - is a major global concern, placing a huge burden on healthcare systems, physicians, and patients. It challenges the current biomedical paradigm, in particular conventional evidence-based medicine's dominant focus on single-conditions. Patients' heterogeneous range of clinical presentations tend to escape characterization by traditional means of classification, and optimal management cannot be deduced from clinical practice guidelines. In this article, we argue that person-focused care based in complexity science may be a transformational lens through which to view multimorbidity, to complement the specialism focus on each particular disease. The approach offers an integrated and coherent perspective on the person's living environment, relationships, somatic, emotional and cognitive experiences and physiological function. The underlying principles include non-linearity, tipping points, emergence, importance of initial conditions, contextual factors and co-evolution, and the presence of patterned outcomes. From a clinical perspective, complexity science has important implications at the theoretical, practice and policy levels. Three essential questions emerge: (1) What matters to patients? (2) How can we integrate, personalize and prioritize care for whole people, given the constraints of their socio-ecological circumstances? (3) What needs to change at the practice and policy levels to deliver what matters to patients? These questions have no simple answers, but complexity science principles suggest a way to integrate understanding of biological, biographical and contextual factors, to guide an integrated approach to the care of people with multimorbidity

Einfluss CCS-bedingter Zuflüsse auf die CO2-Konzentrationen in Böden - Anforderungen aus Sicht des Bodenschutzes

Im Rahmen des vom Umweltbundesamt finanzierten Projektes (Ufo-Förderkenn¬zeichen: 3709 72 402) wurden potentielle Auswirkungen von CCS bedingten CO2-Zuflüssen auf das Ökosystem Boden beleuchtet. Dazu wurden bisher publizierte Ergebnisse hinsichtlich potentieller Wege des CCS-CO2 in den Boden, Einfluss¬faktoren der CO2-Konzentration im Boden sowie Auswirkungen hoher CO2-Gehalte auf Bodenlebewesen und Bodenfunktionen zusammengestellt und ausgewertet. Aufgrund der Heterogenität der Böden, der zeitlichen Variabilität der Boden¬zustände, sowie der nicht vorhersagbaren Rand¬bedingungen wird vorgeschlagen, mittels deterministischer Prozessmodelle maximal zulässige Flussdichten aus dem Untergrund (im Sinne von „Critical Loads“) abzuschätzen

Yukawa Corrections to Top Quark Production at the LHC in Two- Higgs-Doublet Models

The O(alpha m_t^2/m_W^2) corrections to top quark pair production by gluon-gluon fusion at the LHC are calculated in two-Higgs-doublet models. We find that the correction to the cross-section can exceed about -10% for certain parameter values.Comment: 16-page text in LaTex. uuencoded file for Fig.1-6 will be sent separatel