Phase locking the spin precession in a storage ring

This letter reports the successful use of feedback from a spin polarization measurement to the revolution frequency of a 0.97 GeV/$c$ bunched and polarized deuteron beam in the Cooler Synchrotron (COSY) storage ring in order to control both the precession rate ($\approx 121$ kHz) and the phase of the horizontal polarization component. Real time synchronization with a radio frequency (rf) solenoid made possible the rotation of the polarization out of the horizontal plane, yielding a demonstration of the feedback method to manipulate the polarization. In particular, the rotation rate shows a sinusoidal function of the horizontal polarization phase (relative to the rf solenoid), which was controlled to within a one standard deviation range of $\sigma = 0.21$ rad. The minimum possible adjustment was 3.7 mHz out of a revolution frequency of 753 kHz, which changes the precession rate by 26 mrad/s. Such a capability meets a requirement for the use of storage rings to look for an intrinsic electric dipole moment of charged particles

Nature's lessons in design: nanomachines to scaffold, remodel and shape membrane compartments.

Compartmentalisation of cellular processes is fundamental to regulation of metabolism in Eukaryotic organisms and is primarily provided by membrane-bound organelles. These organelles are dynamic structures whose membrane barriers are continually shaped, remodelled and scaffolded by a rich variety of highly sophisticated protein complexes. Towards the goal of bottom-up assembly of compartmentalised protocells in synthetic biology, we believe it will be important to harness and reconstitute the membrane shaping and sculpting characteristics of natural cells. We review different in vitro membrane models and how biophysical investigations of minimal systems combined with appropriate theoretical modelling have been used to gain new insights into the intricate mechanisms of these membrane nanomachines, paying particular attention to proteins involved in membrane fusion, fission and cytoskeletal scaffolding processes. We argue that minimal machineries need to be developed and optimised for employment in artificial protocell systems rather than the complex environs of a living organism. Thus, well-characterised minimal components might be predictably combined into functional, compartmentalised protocellular materials that can be engineered for wide-ranging applications

Spektroskopische Plasmadiagnostik an einer Plasmazelle für die Plasmabeschleunigung.

Für die plasmabasierte Teilchenbeschleunigung ist es wichtig zu wissen, wie sich die Plasmaelektronen- dichte, sowie indirekt auch die Plasmaelektronentemperatur, während des Beschleunigungsprozesses verhalten. Im Rahmen der vorliegenden Bachelorarbeit sollten diese beiden Parameter spektroskopisch an einer Gasentladungsplasmazelle für Plasmabeschleunigungsexperimente bei PITZ, am DESY in Zeuthen,gemessen werden. Zunächst wurden die Durchbruchsspannung für Wasserstoff, Stickstoff und Argon als Hauptgas für die Entladung bestimmt. Durch die Auswertung der Durchbruchsspannungen wurde Wasserstoff als Arbeitsgas für die Dichtemessung gewählt, da die Dichte für mehrere Anregungsniveaus (Wasserstoff-Balmer-Serie) einfach zu bestimmen ist. Nach der Kalibration eines Echelle-Spektrometersmit Blaze-Winkel Gitter wurde das emittierte Licht des Plasmas aus der Plasmazelle mit diesem ausgewertet. Dabei wurde aus der Stark-Linienbreite der H$\alpha$-Linie und Hβ-Linie die Plasmadichte bestimmt und so Plasmaelektronendichten im Breich von 8 bis 15 · 10$^{15}$ cm$^{−3}$ ermittelt. Der Einfluss von anderen Verbreitungsmechanismen auf die Messergebnisse wurde abgeschätzt und der Messfehler bestimmt. Desweiteren wurde die Plasmatemperatur aus dem Verhältnis der Peakintensität des Gesamtspektrums berechnet. Durch eine unbekannte Spektometertansmission konnte jedoch kein sinvolles Ergebnis ermittelt werden. Während der Messungen traten Stabilitätprobleme der einzelnen Strompulse, die das dichte Plasma erzeugen, auf. Die Standartabweichung der Delays der Strompulsen beträgt ± 0,98μs, was bei einer gemessenen Entwicklung des Plasmas auf der gleichen Zeitskala den größten Messfehler erzeugte. DieErgebnisse wurden im Hinblick auf ihre Bedeutung für die Plasmabeschleunigungsexperimente bei PITZ interpretiert und ein Ausblick auf künftige Experimente gegeben

Recommendations Report

The project European Airport Movement Management by A-SMGCS (EMMA), an Integrated Project launched by the European Commission in its sixth framework programme, was executed between March 2004 and April 2006. The aim of the EMMA project was to mature and validate the A-SMGCS concept levels 1 and 2 by setting de facto standards for A-SMGCS systems and their operational usage and by the streamlining of existing products. The EMMA project brought A-SMGCS one further step towards the harmonised European implementation of A-SMGCS. In close cooperation with EUROCONTROL, the advanced operational concept for A-SMGCS levels 1 and 2 has been proven and strengthened by the implementation of levels 1 and 2 A-SMGCS and extensive validation and verification activities at three different European airports: Milano-Malpensa, Prague-Ruzyne, and Toulouse-Blagnac. In Prague-Ruzyne, controllers went as far as to work with the system in low visibility conditions, although this was not expected within the time-frame of the EMMA project. Measurement indicators and test procedures were defined and a significant amount of data was collected during the functional and operational tests. Controllers and pilots actively participated and contributed to the results. The analysis resulted in detailed recommendations covering: • the concept of an A-SMGCS levels 1 and 2, • the technical and operational requirements, • procedures, • implementation issues (e.g. safety assessment, training and licensing), and • detailed recommendations for a harmonised A-SMGCS V and V methodology. Further on, this document provides detailed recommendations to the respective stakeholders (i.e. users, research institutions, industry, and the European Commission as the contractor). In an additional innovative study, a preliminary concept and an implementation roadmap for a complete A-SMGCS, considering higher-level services like routing, planning, and the air-ground integration, has been proposed to prepare the successor project EMMA2

A Comparative Study of the Mass Distribution of Extreme-Ultraviolet selected White Dwarfs

Original article can be found at: http://www.journals.uchicago.edu/ApJ/--Copyright American Astronomical SocietyWe present new determinations of e ective temperature, surface gravity, and masses for a sample of 46 hot DA white dwarfs selected from the Extreme Ultraviolet Explorer (EUV E) and ROSAT Wide Field Camera bright source lists in the course of a near-infrared survey for low-mass companions. Our analysis, based on hydrogen non-LTE model atmospheres, provides a map of LTE correction vectors, which allow a thorough comparison with previous LTE studies. We Ðnd that previous studies underestimate both the systematic errors and the observational scatter in the determination of white dwarf parameters obtained via Ðts to model atmospheres. The structure of very hot or low-mass white dwarfs depends sensitively on their history. To compute white dwarf masses, we thus use theoretical mass-radius relations that take into account the complete evolution from the main sequence. We Ðnd a peak mass of our white dwarf sample of 0.59 M in agreement with the results of previous analyses. However, we do _, not conÐrm a trend of peak mass with temperature reported in two previous analyses. Analogous to other EUV-selected samples, we note a lack of low-mass white dwarfs and a large fraction of massive white dwarfs. Only one white dwarf is likely to have a helium core. While the lack of helium white dwarfs in our sample can be easily understood from their high cooling rate, and therefore low detection probability in our temperature range, this is not enough to explain the large fraction of massive white dwarfs. This feature very likely results from a decreased relative sample volume for low-mass white dwarfs caused by interstellar absorption in EUV-selected samples.Peer reviewe