Local councillors in comparative perspective: drawing conclusions

The chapters of this book contain the first results of our common research project. They show a rich picture of many aspects of local councillors in 16 countries. It is not the intention of the group that this is the final output from the project. On the contrary: these analyses should be only a first step in the use of this valuable dataset. Further analysis and publications are under way and are foreseen in the future

Optical turbulence vertical distribution with standard and high resolution at Mt. Graham

A characterization of the optical turbulence vertical distribution (Cn2 profiles) and all the main integrated astroclimatic parameters derived from the Cn2 and the wind speed profiles above the site of the Large Binocular Telescope (Mt. Graham, Arizona, US) is presented. The statistic includes measurements related to 43 nights done with a Generalized Scidar (GS) used in standard configuration with a vertical resolution Delta(H)~1 km on the whole 20 km and with the new technique (HVR-GS) in the first kilometer. The latter achieves a resolution Delta(H)~20-30 m in this region of the atmosphere. Measurements done in different periods of the year permit us to provide a seasonal variation analysis of the Cn2. A discretized distribution of Cn2 useful for the Ground Layer Adaptive Optics (GLAO) simulations is provided and a specific analysis for the LBT Laser Guide Star system ARGOS (running in GLAO configuration) case is done including the calculation of the 'gray zones' for J, H and K bands. Mt. Graham confirms to be an excellent site with median values of the seeing without dome contribution epsilon = 0.72", the isoplanatic angle theta0 = 2.5" and the wavefront coherence time tau0= 4.8 msec. We find that the optical turbulence vertical distribution decreases in a much sharper way than what has been believed so far in proximity of the ground above astronomical sites. We find that 50% of the whole turbulence develops in the first 80+/-15 m from the ground. We finally prove that the error in the normalization of the scintillation that has been recently put in evidence in the principle of the GS technique, affects these measurements with an absolutely negligible quantity (0.04").Comment: 11 figures. MNRAS, accepte

WxWindows Interface for CALE

wxWindows is an Open Source, platform independent, User Interface (UI) which has been in development for over eleven years (http://www.wxwindows.org). Currently wxWindows is actively supported for the Linux/Unix (X11, Motif and GTK+), Mac OS 9 and X, all Win32 OSes, MGL, and OS/2 operating systems. wxWindows is written in C++ using an object oriented programming framework; it is a reasonably lightweight API (called wxWidgets) sitting over the native graphics packages of the various platforms it supports. The original version of CALE was written for the basic target platform of Unix using X11 as the graphics package. There have been separate efforts to port the code to Mac OS 9, Mac OS X, Win32, Windows Services for Unix (SFU) and CygWin. Each of these used a variety of different graphical interface approaches and build/make systems. For instance Windows SFU and CygWin could still only use X11 graphics. So could the Win32 version, if a X11 server library and client software were installed. A native Win32 version of CALE was contemplated, but never started. The Macintosh versions were completed but never widely distributed to the users. Given the growing code version support issues, and the slow deviation from the portable code model CALE originally started with, it was desired to come up with a simple graphical UI that would be cross platform portable with only a single code base and build system. During the past two summers, two Laboratory summer students and a CALE team code physicist have worked on porting CALE to the wxWidgets UI. In the summer of 2003 Jeffery Hagelberg (formerly Purdue University, now at the University of California-Davis) started the project. During the spring & summer of 2004 Christopher Egner (Rochester Institute of Technology) completed the work. Paul Amala (A/X-Program at LLNL) supervised the students for their combined 30 weeks of effort. This poster session describes the wxWindows interface as it is implemented in CALE, the level of cross platform portable it actually affords, and the lessons learned during the porting of an existing X11 program to this open source software package. (U

Drift estimation in sparse sequential dynamic imaging, with application to nanoscale fluorescence microscopy.

A major challenge in many modern superresolution fluorescence microscopy techniques at the nanoscale lies in the correct alignment of long sequences of sparse but spatially and temporally highly resolved images. This is caused by the temporal drift of the protein structure, e.g. due to temporal thermal inhomogeneity of the object of interest or its supporting area during the observation process. We develop a simple semiparametric model for drift correction in single-marker switching microscopy. Then we propose an M-estimator for the drift and show its asymptotic normality. This is used to correct the final image and it is shown that this purely statistical method is competitive with state of the art calibration techniques which require the incorporation of fiducial markers in the specimen. Moreover, a simple bootstrap algorithm allows us to quantify the precision of the drift estimate and its effect on the final image estimation. We argue that purely statistical drift correction is even more robust than fiducial tracking, rendering the latter superfluous in many applications. The practicability of our method is demonstrated by a simulation study and by a single-marker switching application. This serves as a prototype for many other typical imaging techniques where sparse observations with high temporal resolution are blurred by motion of the object to be reconstructed

Ground-layer wavefront reconstruction from multiple natural guide stars

Observational tests of ground layer wavefront recovery have been made in open loop using a constellation of four natural guide stars at the 1.55 m Kuiper telescope in Arizona. Such tests explore the effectiveness of wide-field seeing improvement by correction of low-lying atmospheric turbulence with ground-layer adaptive optics (GLAO). The wavefronts from the four stars were measured simultaneously on a Shack-Hartmann wavefront sensor (WFS). The WFS placed a 5 x 5 array of square subapertures across the pupil of the telescope, allowing for wavefront reconstruction up to the fifth radial Zernike order. We find that the wavefront aberration in each star can be roughly halved by subtracting the average of the wavefronts from the other three stars. Wavefront correction on this basis leads to a reduction in width of the seeing-limited stellar image by up to a factor of 3, with image sharpening effective from the visible to near infrared wavelengths over a field of at least 2 arc minutes. We conclude that GLAO correction will be a valuable tool that can increase resolution and spectrographic throughput across a broad range of seeing-limited observations.Comment: 25 pages, 8 figures, to be published in Astrophys.

‘Surface Contrast’ NMR reveals non‐innocent role of support in Pd/CeO2 catalyzed phenol hydrogenation

Ceria (CeO 2 )‐supported metals are widely used as catalysts because of their exceptional redox properties. Here, we use surface contrast NMR methods to investigate the hydrogenation of phenol by Pd supported on ceria nanoparticles. We show that the rigid and planar binding of phenol to Pd is mediated by a weak and highly mobile association of the small molecule to ceria. Interestingly, while addition of phosphate to the mixture does not perturb the adsorption of phenol on Pd, it destabilizes its interaction with ceria and proportionally decreases the rate of catalytic conversion. Our data provide strong experimental evidence that weak interactions between adsorbate and ceria are catalytically competent, and explain the exceptional performance of Pd/CeO 2 for reductive conversions under mild reaction conditions