CCCP: A CCD Controller for Counting Photons

CCCP, a CCD Controller for Counting Photons, is presented. This new controller uses a totally new clocking architecture and allows to drive the CCD in a novel way. Its design is optimized for the driving of EMCCDs at up to 20MHz of pixel rate and fast vertical transfer. Using this controller, the dominant source of noise of EMCCDs at low flux level and high frame rate, the Clock Induced Charges, were reduced to 0.001 - 0.0018 electron/pixel/frame (depending of the electron multiplying gain), making efficient photon counting possible. CCCP will be deployed in 2009 on the ESO NTT through the 3D-NTT1 project and on the SOAR through the BTFI project.Comment: 10 pages, 10 figures, to appear in "Ground-based and Airborne Instrumentation for Astronomy II" SPIE conference, Marseille, 23-28 June 200

Extreme faint flux imaging with an EMCCD

An EMCCD camera, designed from the ground up for extreme faint flux imaging, is presented. CCCP, the CCD Controller for Counting Photons, has been integrated with a CCD97 EMCCD from e2v technologies into a scientific camera at the Laboratoire d'Astrophysique Experimentale (LAE), Universite de Montreal. This new camera achieves sub-electron read-out noise and very low Clock Induced Charge (CIC) levels, which are mandatory for extreme faint flux imaging. It has been characterized in laboratory and used on the Observatoire du Mont Megantic 1.6-m telescope. The performance of the camera is discussed and experimental data with the first scientific data are presented.Comment: 33 pages, 17 figures, accepted for publication in PAS

Lead Isotopic Composition of Fly Ash and Flue Gas Residues from Municipal Solid Waste Combustors in France: Implications for Atmospheric Lead Source Tracing.

Fly ash and flue gas residues from eight municipal solid waste combustors (MSWC) in France (1992-93 and 1998/2002) were analyzed for their Pb isotopic composition. Fly ashes are more representative of solid residual particles, whereas flue gas residues reflect mostly the composition of gas phases. Both sample types contain hundreds to thousands of micrograms of metals per gram. Leaching experiments showed that metals are present in condensed phases, probably as sulfates and chlorides, and suggest that Cd, Pb, and Zn are highly fractionated from one another during volatilization/condensation processes occurring during combustion. Although all the samples analyzed define a fairly restricted range in Pb isotopic compositions (206Pb/207Pb = 1.148-1.158 and 208Pb/206Pb = 2.101-2.114) compared to other environmental samples, some MSWC produce materials having distinct isotopic compositions, whereas others display very similar ones. Isotopic heterogeneity is also measured between samples from a single MSWC. This is interpreted as resulting from the heterogeneity of the waste source materials. The range of Pb isotopic composition of incinerator materials form a well-defined linear array in the 208Pb/206Pb versus 206Pb/207Pb diagram. This array is compatible with the previously reported European standard pollution (ESP) line and most probably represent the average lead isotopic composition of industrial atmospheric emissions in France, with the following ratios: 206Pb/207Pb = 1.154 ± 0.003 and 208Pb/206Pb = 2.107 ± 0.003 (1)

L3CCD results in pure photon counting mode

Theoretically, L3CCDs are perfect photon counting devices promising high quantum efficiency ($\sim$90%) and sub-electron readout noise ($\sigma$<0.1 e-). We discuss how a back-thinned 512x512 frame-transfer L3CCD (CCD97) camera operating in pure photon counting mode would behave based on experimental data. The chip is operated at high electromultiplication gain, high analogic gain and high frame rate. Its performance is compared with a modern photon counting camera (GaAs photocathode, QE $\sim$28%) to see if L3CCD technology, in its current state, could supersede photocathode-based devices.Comment: 9 pages, 9 figures, to appear in SPIE conference proceedings vol 5499, "Optical & IR Detectors for Astronomy" Glasgow UK, 21-24 June 200

Changes in physiological tremor associated with an epileptic seizure: a case report

<p>Abstract</p> <p>Introduction</p> <p>Epileptic seizures are associated with motor, sensory, somatosensory or autonomic symptoms that have all been described in varying detail over the years. Of interest in the present report is a case of normal physiological tremor, which to date has never been evaluated prior to and during an epileptic seizure. In fact, there is only anecdotal mention of pre-ictal and ictal changes in clinically noticeable tremor in the literature.</p> <p>Case presentation</p> <p>Our patient was a left-handed, 27-year-old Caucasian woman diagnosed seven years previously with partial epileptic seizures, secondarily generalized. Physiological tremor was measured simultaneously on the index finger of both hands of our patient. Electromyography as well as heart rate and respiration were also monitored. A previously performed electroencephalography examination revealed abnormal oscillations focalized to the left primary somatosensory cortex. She was also diagnosed with left frontal neuronal heterotopias. We detected subclinical changes in tremor characteristics, such as amplitude, median power frequency and power dispersion, contralateral to the localization of epileptic activity. Tremor characteristics remained relatively steady ipsilateral to the localization of the epileptic activity.</p> <p>Conclusions</p> <p>Changes in physiological tremor characteristics should be considered as another possible pre-ictal or ictal manifestation. We propose that the network associated with physiological tremor might be more sensitive to abnormal oscillations generated within the central nervous system by epileptic activity from certain structures.</p

Spiral inflow feeding the nuclear starburst in M83, observed in H-alpha emission with the GHAFAS Fabry-Perot interferometer

We present observations of the nearby barred starburst galaxy, M83 (NGC5236), with the new Fabry-Perot interferometer GHAFAS mounted on the 4.2 meter William Herschel Telescope on La Palma. The unprecedented high resolution observations, of 16 pc/FWHM, of the H-alpha-emitting gas cover the central two kpc of the galaxy. The velocity field displays the dominant disk rotation with signatures of gas inflow from kpc scales down to the nuclear regions. At the inner Inner Lindblad Resonance radius of the main bar and centerd at the dynamical center of the main galaxy disk, a nuclear $5.5 (\pm 0.9) \times 10^8 M_\odot$ rapidly rotating disk with scale length of $60 \pm 20$ pc has formed. The nuclear starburst is found in the vicinity as well as inside this nuclear disk, and our observations confirm that gas spirals in from the outer parts to feed the nuclear starburst, giving rise to several star formation events at different epochs, within the central 100 pc radius of M83.Comment: Accepted for publication in ApJ Letters. High-resolution version can be found at http://www.astro.su.se/~kambiz/DOC/paper-M83.pd

CO(1-0), CO(2-1) and Neutral Gas in NGC 6946: Molecular Gas in a Late-Type, Gas Rich, Spiral Galaxy

We present "On The Fly" maps of the CO(1-0) and CO(2-1) emission covering a 10' X 10' region of the NGC 6946. Using our CO maps and archival VLA HI observations we create a total gas surface density map, Sigma_gas, for NGC 6946. The predominantly molecular inner gas disk transitions smoothly into an atomic outer gas disk, with equivalent atomic and molecular gas surface densities at R = 3.5' (6 kpc). We estimate that the total H2 mass is 3 X 10^9 Mo, roughly 1/3 of the interstellar hydrogen gas mass, and about 2% of the dynamical mass of the galaxy at our assumed distance of 6 Mpc. The value of the CO(2-1)/CO(1-0) line ratio ranges from 0.35 to 2; 50% of the map is covered by very high ratio, >1, gas. The very high ratios are predominantly from interarm regions and appear to indicate the presence of wide-spread optically thin gas. Star formation tracers are better correlated with the total neutral gas disk than with the molecular gas by itself implying SFR is proportional to Sigma_gas. Using the 100 FIR and 21 cm continuum from NGC 6946 as star formation tracers, we arrive at a gas consumption timescale of 2.8 Gyr, which is relatively uniform across the disk. The high star formation rate at the nucleus appears to be due to a large accumulation of molecular gas rather than a large increase in the star formation efficiency. The mid-plane gas pressure in the outer (R > 10 kpc) HI arms of NGC 6946 is close to the value at the radial limit (10 kpc) of our observed CO disk. If the mid-plane gas pressure is a factor for the formation of molecular clouds, these outer HI gas arms should contain molecular gas which we do not see because they are beyond our detection limit

The Brazilian Tunable Filter Imager for the SOAR telescope

This paper presents a new Tunable Filter Instrument for the SOAR telescope. The Brazilian Tunable Filter Imager (BTFI) is a versatile, new technology, tunable optical imager to be used in seeing-limited mode and at higher spatial fidelity using the SAM Ground-Layer Adaptive Optics facility at the SOAR telescope. The instrument opens important new science capabilities for the SOAR community, from studies of the centers of nearby galaxies and the insterstellar medium to statistical cosmological investigations. The BTFI takes advantage of three new technologies. The imaging Bragg Tunable Filter concept utilizes Volume Phase Holographic Gratings in a double-pass configuration, as a tunable filter, while a new Fabry-Perot (FP) concept involves technologies which allow a single FP etalon to act over a large range of interference orders and spectral resolutions. Both technologies will be in the same instrument. Spectral resolutions spanning the range between 25 and 30,000 can be achieved through the use of iBTF at low resolution and scanning FPs beyond R ~2,000. The third new technologies in BTFI is the use of EMCCDs for rapid and cyclically wavelength scanning thus mitigating the damaging effect of atmospheric variability through data acquisition. An additional important feature of the instrument is that it has two optical channels which allow for the simultaneous recording of the narrow-band, filtered image with the remaining (complementary) broad-band light. This avoids the uncertainties inherent in tunable filter imaging using a single detector. The system was designed to supply tunable filter imaging with a field-of-view of 3 arcmin on a side, sampled at 0.12" for direct Nasmyth seeing-limited area spectroscopy and for SAM's visitor instrument port for GLAO-fed area spectroscopy. The instrument has seen first light, as a SOAR visitor instrument. It is now in comissioning phase.Comment: accepted in PAS

The future of dialects: Selected papers from Methods in Dialectology XV

Traditional dialects have been encroached upon by the increasing mobility of their speakers and by the onslaught of national languages in education and mass media. Typically, older dialects are “leveling” to become more like national languages. This is regrettable when the last articulate traces of a culture are lost, but it also promotes a complex dynamics of interaction as speakers shift from dialect to standard and to intermediate compromises between the two in their forms of speech. Varieties of speech thus live on in modern communities, where they still function to mark provenance, but increasingly cultural and social provenance as opposed to pure geography. They arise at times from the need to function throughout the different groups in society, but they also may have roots in immigrants’ speech, and just as certainly from the ineluctable dynamics of groups wishing to express their identity to themselves and to the world. The future of dialects&nbsp;is a selection of the papers presented at Methods in Dialectology XV, held in Groningen, the Netherlands, 11-15 August 2014. While the focus is on methodology, the volume also includes specialized studies on varieties of Catalan, Breton, Croatian, (Belgian) Dutch, English (in the US, the UK and in Japan), German (including Swiss German), Italian (including Tyrolean Italian), Japanese, and Spanish as well as on heritage languages in Canada