The Pulsed Power Converter and Septum Magnet System for Injection into the Electron Storage Ring at ESRF

At ESRF, the European Synchrotron Radiation Facility in Grenoble, electrons are accelerated, via a 200 MeV Linac and a 6 GeV synchrotron booster, and injected into the storage ring at 10 Hz rate. Two thin septum blade magnets and an eddy current sheet type septum magnet provide the final deflection of the injected beam. The operational requirements of the e- injection scheme and the resulting demanding hardware specifications are recalled. The pulsed septum magnets are briefly described. The design, circuit layout and construction of the power converters are related with emphasis on innovative aspects of general interest. Results of tests during commissioning are reported

X-ray/Optical/Radio Observations of a Resolved Supernova Remnant in NGC 6822

The supernova remnant (SNR), Ho 12, in the center of the dwarf irregular galaxy NGC 6822 was previously observed at X-ray, optical, and radio wavelengths. By using archival Chandra and ground-based optical data, we found that the SNR is spatially resolved in X-rays and optical. In addition, we obtained a ~5" resolution radio image of the SNR. These observations provide the highest spatial resolution imaging of an X-ray/optical/radio SNR in that galaxy to date. The multi-wavelength morphology, X-ray spectrum and variability, and narrow-band optical imagings are consistent with a SNR. The SNR is a shell-shaped object with a diameter of about 10" (24 pc). The morphology of the SNR is consistent across the wavelengths while the Chandra spectrum can be well fitted with a nonequilibrium ionization model with an electron temperature of 2.8 keV and a 0.3-7 keV luminosity of 1.6e37 erg/s. The age of the SNR is estimated to be 1700-5800 years.Comment: 6 pages, 3 figures, accepted for publication in the Astronomical Journa

Transparent and feasible uncertainty assessment adds value to applied ecosystem services modeling

We introduce a special issue that aims to simultaneously motivate interest in uncertainty assessment (UA) and reduce the barriers practitioners face in conducting it. The issue, “Demonstrating transparent, feasible, and useful uncertainty assessment in ecosystem services modeling,” responds to findings from a 2016 workshop of academics and practitioners that identified challenges and potential solutions to enhance the practice of uncertainty assessment in the ES community. Participants identified that one important gap was the lack of a compelling set of cases showing that UA can be feasibly conducted at varying levels of sophistication, and that such assessment can usefully inform decision-relevant modeling conclusions. This article orients the reader to the 11 other articles that comprise the special issue, and which span multiple methods and application domains, all with an explicit consideration of uncertainty. We highlight the value of UA demonstrated in the articles, including changing decisions, facilitating transparency, and clarifying the nature of evidence. We conclude by suggesting ways to promote further adoption of uncertainty analysis in ecosystem service assessments. These include: Easing the analytic workflows involved in UA while guarding against rote analyses, applying multiple models to the same problem, and learning about the conduct and value of UA from other disciplines

Multicomplementary operators via finite Fourier transform

A complete set of d+1 mutually unbiased bases exists in a Hilbert spaces of dimension d, whenever d is a power of a prime. We discuss a simple construction of d+1 disjoint classes (each one having d-1 commuting operators) such that the corresponding eigenstates form sets of unbiased bases. Such a construction works properly for prime dimension. We investigate an alternative construction in which the real numbers that label the classes are replaced by a finite field having d elements. One of these classes is diagonal, and can be mapped to cyclic operators by means of the finite Fourier transform, which allows one to understand complementarity in a similar way as for the position-momentum pair in standard quantum mechanics. The relevant examples of two and three qubits and two qutrits are discussed in detail.Comment: 15 pages, no figure

Stereotaxic injection of a viral vector for conditional gene manipulation in the mouse spinal cord.

Intraparenchymal injection of a viral vector enables conditional gene manipulation in distinct populations of neurons or particular regions of the central nervous system. We demonstrate a stereotaxic injection technique that allows targeted gene expression or silencing in the dorsal horn of the mouse spinal cord. The surgical procedure is brief. It requires laminectomy of a single vertebra, providing for quick recovery of the animal and unimpaired motility of the spine. Controlled injection of a small vector suspension volume at low speed and use of a microsyringe with beveled glass cannula minimize the tissue lesion. The local immune response to the vector depends on the intrinsic properties of the virus employed; in our experience, it is minor and short-lived when a recombinant adeno-associated virus is used. A reporter gene such as enhanced green fluorescent protein facilitates monitoring spatial distribution of the vector, and the efficacy and cellular specificity of the transfection.journal articleresearch support, n.i.h., extramuralvideo-audio media2013 Mar 182013 03 18importe

Evidence for tidal interaction and a supergiant HI shell in the Local Group dwarf galaxy NGC 6822

We present a wide-field, high spatial and velocity resolution map of the entire extended HI distribution of the Local Group dwarf galaxy NGC 6822. The observations were obtained with the Australia Telescope Compact Array in mosaicing mode. The interstellar medium of NGC 6822 is shaped by the presence of numerous H{\sc i} holes and shells, including a supergiant shell, and the effects of tidal interaction, in the form of a tidal arm and an infalling or interacting HI complex. The HI shell is situated outside the optical galaxy and occupies roughly a quarter of the area of the main HI disk. It measures 2.0 times 1.4 kpc, making it one of the largest supergiant HI shells ever found. The giant hole shows no signs of expansion and no obvious creation mechanism is evident from our data. If star formation was the cause, an energy equivalent of \~100 supernovae (10^53 erg) is needed to create the hole. We derive an upper limit for the age of order 100 Myr. The presence of a possible tidal arm indicates that NGC 6822 may recently have undergone some interaction. An HI complex located in the north-west of the galaxy may be the interaction partner. We argue that it is likely that these features were created about 100 Myr ago in an event that also enhanced the star formation rateComment: Accepted for publication in Astrophysical Journal Letters (needs emulateapj5.sty, included

The stellar population and interstellar medium in NGC 6822

We present a comprehensive study of the stellar population and the interstellar medium in NGC 6822 using high-quality \HI data (obtained with the Australia Telescope Compact Array) and optical broad/narrow-band data (obtained with Subaru and the INT). Our H$\alpha$ observations are an order of magnitude deeper than previous studies and reveal a complex filamentary network covering almost the entire central disk of NGC 6822. We find hitherto unknown HII regions in the outskirts of NGC 6822 and the companion galaxy. The old and intermediate age stellar population can be traced out to radii of over 0.6 deg (> 5 kpc), significantly more extended than the HI disk. In sharp contrast, the distribution of the young, blue stars, closely follows the distribution of the HI disk and displays a highly structured morphology. We find evidence for an older stellar population in the companion galaxy -- the current star formation activity, although likely to have been triggered by the interaction with NGC 6822, is not the first star formation episode in this object. We show that the properties of the giant kpc-sized hole in the outer HI disk of NGC 6822 are consistent with it being formed by the effects of stellar evolution.Comment: Accepted for publication in AJ. Full version with high-resolution figures available at http://www.mso.anu.edu.au/~edeblok/papers/6822_paper1.ps.g

A Survey of Finite Algebraic Geometrical Structures Underlying Mutually Unbiased Quantum Measurements

The basic methods of constructing the sets of mutually unbiased bases in the Hilbert space of an arbitrary finite dimension are discussed and an emerging link between them is outlined. It is shown that these methods employ a wide range of important mathematical concepts like, e.g., Fourier transforms, Galois fields and rings, finite and related projective geometries, and entanglement, to mention a few. Some applications of the theory to quantum information tasks are also mentioned.Comment: 20 pages, 1 figure to appear in Foundations of Physics, Nov. 2006 two more references adde

Development of the ECOSAR P-Band Synthetic Aperture Radar

This paper describes objectives and recent progress on the development of the EcoSAR, a new P-band airborne radar instrument being developed at the NASA/ Goddard Space Flight Center (GSFC) for the polarimetric and interferometric measurements of ecosystem structure and biomass. These measurements support science requirements for the study of the carbon cycle and its relationship to climate change. The instrument is scheduled to be completed and flight tested in 2013. Index Terms SAR, Digital Beamforming, Interferometry