Peak wind speed anemometers /maxometer/ Final report, 26 Mar. 1969 - 25 May 1970

Fabrication and testing of peak wind speed recording devic

Electrodynamic Structure of an Outer Gap Accelerator: Location of the Gap and the Gamma-ray Emission from the Crab Pulsar

We investigate a stationary pair production cascade in the outer magnetosphere of a spinning neutron star. The charge depletion due to global flows of charged particles, causes a large electric field along the magnetic field lines. Migratory electrons and/or positrons are accelerated by this field to radiate curvature gamma-rays, some of which collide with the X-rays to materialize as pairs in the gap. The replenished charges partially screen the electric field, which is self-consistently solved together with the distribution functions of particles and gamma-rays. If no current is injected at neither of the boundaries of the accelerator, the gap is located around the conventional null surface, where the local Goldreich-Julian charge density vanishes. However, we first find that the gap position shifts outwards (or inwards) when particles are injected at the inner (or outer) boundary. Applying the theory to the Crab pulsar, we demonstrate that the pulsed TeV flux does not exceed the observational upper limit for moderate infrared photon density and that the gap should be located near to or outside of the conventional null surface so that the observed spectrum of pulsed GeV fluxes may be emitted via a curvature process. Some implications of the existence of a solution for a super Goldreich-Julian current are discussed.Comment: 17 pages, 12 figures, submitted to Ap

Functional specialization of the yeast Rho1 GTP exchange factors

Rho GTPases are regulated in complex spatiotemporal patterns that may be dependent, in part at least, on the multiplicity of their GTP exchange factors (GEFs). Here, we examine the extent of and basis for functional specialization of the Rom2 and Tus1 GEFs that activate the yeast Rho1 GTPase, the ortholog of mammalian RhoA. First, we find that these GEFs selectively activate different Rho1-effector branches. Second, the synthetic genetic networks around ROM2 and TUS1 confirm very different global in vivo roles for these GEFs. Third, the GEFs are not functionally interchangeable: Tus1 cannot replace the essential role of Rom2, even when overexpressed. Fourth, we find that Rom2 and Tus1 localize differently: Rom2 to the growing bud surface and to the bud neck at cytokinesis; Tus1 only to the bud neck but in a distinct pattern. Finally, we find that these GEFs are dependent on different protein co-factors: Rom2 function and localization is largely dependent on Ack1, a SEL1 domain containing protein; Tus1 function and localization is largely dependent on the Tus1-interacting protein Ypl066w (which we name Rgl1). We have revealed a surprising level of diversity among the Rho1 GEFs that contributes another level of complexity to the spatiotemporal control of Rho1

The effects of parasitism and body length on positioning within wild fish shoals

The influence of body length and parasitism on the positioning behaviour of individuals in wild fish shoals was investigated by a novel means of capturing entire shoals of the banded killifish (Fundulus diaphanus, Lesueur) using a grid-net that maintained the two-dimensional positions of individuals within shoals. Fish in the front section of a shoal were larger than those in the rear. Individuals parasitized by the digenean trematode (Crassiphiala bulboglossa, Haitsma) showed a tendency to occupy the front of shoals. Parasitized fish were also found more in peripheral positions than central ones in a significant number of shoals. Shoal geometry was affected by the overall parasite prevalence of shoal members; shoals with high parasite prevalence displayed increasingly phallanx-like shoal formations, whereas shoals with low prevalence were more elliptical. There was no relationship between body length and parasite abundance or prevalence in the fish population which suggests body length and parasite status are independent predictors of positioning behaviour. Solitary individuals found outside shoals were both more likely to be parasitized and had higher parasite abundance than individuals engaged in shoaling. Differences in the shoaling behaviour of parasitized and unparasitized fish are discussed in the context of the adaptive manipulation hypothesis

Radio Continuum Jet in NGC 7479

The barred galaxy NGC 7479 hosts a remarkable jet-like radio continuum feature: bright, 12-kpc long in projection, and hosting an aligned magnetic field. The degree of polarization is 6%-8% along the jet, and remarkably constant, which is consistent with helical field models. The radio brightness of the jet suggests strong interaction with the ISM and hence a location near the disk plane. We observed NGC 7479 at four wavelengths with the VLA and Effelsberg radio telescopes. The equipartition strength is 35-40 micro-G for the total and >10 micro-G for the ordered magnetic field in the jet. The jet acts as a bright, polarized background. Faraday rotation between 3.5 and 6 cm and depolarization between 6 and 22 cm can be explained by magneto-ionic gas in front of the jet, with thermal electron densities of ~0.06 cm**(-3) in the bar and ~0.03 cm**(-3) outside the bar. The regular magnetic field along the bar points toward the nucleus on both sides. The regular field in the disk reveals multiple reversals, probably consisting of field loops stretched by a shearing gas flow in the bar. The projection of the jet bending in the sky plane is in the sense opposite to that of the underlying stellar and gaseous spiral structure. The bending in 3-D is most easily explained as a precessing jet, with an age less than 10**6 years. Our observations are consistent with very recent triggering, possibly by a minor merger. NGC 7479 provides a unique opportunity to study interaction-triggered 15-kpc scale radio jets within a spiral galaxy.Comment: 18 pages, 21 figures, accepted for publication in the Astrophysical Journa

Integrated Structure and Semantics for Reo Connectors and Petri Nets

In this paper, we present an integrated structural and behavioral model of Reo connectors and Petri nets, allowing a direct comparison of the two concurrency models. For this purpose, we introduce a notion of connectors which consist of a number of interconnected, user-defined primitives with fixed behavior. While the structure of connectors resembles hypergraphs, their semantics is given in terms of so-called port automata. We define both models in a categorical setting where composition operations can be elegantly defined and integrated. Specifically, we formalize structural gluings of connectors as pushouts, and joins of port automata as pullbacks. We then define a semantical functor from the connector to the port automata category which preserves this composition. We further show how to encode Reo connectors and Petri nets into this model and indicate applications to dynamic reconfigurations modeled using double pushout graph transformation

A maxometer for peak wind speed anemometery Final report, 26 Mar. 1969 - 25 May 1970

Maxometers for peak wind speed anemometry for Saturn 5 launch umbilical tower and normal meteorological environmen

Active Brownian particles with velocity-alignment and active fluctuations

We consider a model of active Brownian particles with velocity-alignment in two spatial dimensions with passive and active fluctuations. Hereby, active fluctuations refers to purely non-equilibrium stochastic forces correlated with the heading of an individual active particle. In the simplest case studied here, they are assumed as independent stochastic forces parallel (speed noise) and perpendicular (angular noise) to the velocity of the particle. On the other hand, passive fluctuations are defined by a noise vector independent of the direction of motion of a particle, and may account for example for thermal fluctuations. We derive a macroscopic description of the active Brownian particle gas with velocity-alignment interaction. Hereby, we start from the individual based description in terms of stochastic differential equations (Langevin equations) and derive equations of motion for the coarse grained kinetic variables (density, velocity and temperature) via a moment expansion of the corresponding probability density function. We focus here in particular on the different impact of active and passive fluctuations on the onset of collective motion and show how active fluctuations in the active Brownian dynamics can change the phase-transition behaviour of the system. In particular, we show that active angular fluctuation lead to an earlier breakdown of collective motion and to emergence of a new bistable regime in the mean-field case.Comment: 5 figures, 22 pages, submitted to New Journal of Physic

Quantum Monte Carlo study of a positron in an electron gas

Quantum Monte Carlo calculations of the relaxation energy, pair-correlation function, and annihilating-pair momentum density are presented for a positron immersed in a homogeneous electron gas. We find smaller relaxation energies and contact pair-correlation functions in the important low-density regime than predicted by earlier studies. Our annihilating-pair momentum densities have almost zero weight above the Fermi momentum due to the cancellation of electron-electron and electron-positron correlation effects

Mittelfristige Ergebnisse der Vastus-medialis-obliquus-Plastik bei lateraler Patellaluxation

Zusammenfassung: In Langzeitergebnissen nach traditionellen Operationsverfahren distalen Realignements für Patellaluxationen wie z.B. der Tuberositasosteotomie wird eine hohe Rate an Femoropatellararthrosen gefunden, sodass ein operatives Vorgehen noch heute kontrovers diskutiert wird. In der Literatur scheinen die Verfahren mit dynamischem proximalem Realignement eine geringere Arthroserate, aber bisweilen höhere Reluxationsrate aufzuweisen. Unlängst wurde der M.vastus medialis obliquus (VMO) in anatomischen und biomechanischen Studien als eine der entscheidenden proximalen stabilisierenden Strukturen bei lateralen Patellaluxationen identifiziert. Zwischen 1994 und 2003 wurden 28Patienten (Durchschnittsalter 21,5Jahre) mit einer VMO-Plastik bei lateraler Patellaluxation operativ versorgt. Die Technik wurde für die meisten Ätiologien einer femoropatellären Instabilität angewandt. Bei dieser proximalen Weichteilkorrektur wird die sehnige Einstrahlung des VMO von der Patella abgelöst. Anschließend wird die Sehne 10-15mm distalisierend an der Patella über MITEK-Anker reinseriert. Postoperativ ist eine Vollbelastung in Streckung möglich. Ein aktives Auftrainieren des Vastus medialis beginnt 6Wochen nach der Operation. 27Patienten wurden klinisch und radiologisch im Jahre 2004 nachkontrolliert, durchschnittlich 5Jahre nach der Operation. 83% gaben ein exzellentes oder gutes Resultat an, 10% waren zufrieden und 7% unzufrieden. Der durchschnittliche Lysholm-Knie-Score betrug 83,1Punkte. Zwei Patienten erlitten eine Reluxation (7%). Die postoperativen Röntgenbilder zeigten eine signifikante Verbesserung des Kongruenzwinkels auch noch nach vielen Jahren. In 89% der Fälle wurde keine oder eine nur geringe Femoropatellararthrose beobachtet. Die präsentierten Fünfjahresergebnisse sind bezüglich Patientenzufriedenheit mit anderen Verfahren proximalen und distalen Realignements vergleichbar. Die Reluxationsrate ist unterdurchschnittlich. Die bisherige niedrige Rate an Femoropatellararthrose nach durchschnittlich 5Jahren erscheint im Vergleich mit den Arthroseraten des rigiden, distalen Realignements hinsichtlich zukünftiger Langzeitergebnisse vielversprechend und wird auf den minimalen Eingriff in das physiologische Gelenkspiel und auf die Wiederherstellung der verletzten Anatomie zurückgeführt. Die Idee der proximalen dynamischen Stabilisierung und das Angreifen am Ursprung der Pathologie wird in den Erkenntnissen aktueller anatomischer und biomechanischer Untersuchungen bestätigt, was diese relativ guten Ergebnisse erklären mag. Über- und Unterkorrekturen der Weichteile können zurzeit kompensiert werden. Die oben genannten traditionellen und rigideren Operationsmethoden erlauben eine solche Kompensation nicht in diesem Ausmaß und können so zu präarthrotischer Überbelastung des medialen Femoropatellar- und Femorotibialgelenks führe