Far-infrared imaging of tokamak plasma

A 20-channel interferometer has been developed which utilizes a linear, one-dimensional microbolometer array to obtain single-shot density profiles from the UCLA Microtor tokamak plasma. The interferometer has been used to study time-dependent phenomena in the plasma density profile. Observations of the sawtooth instability clearly show the growth of the m=0 mode from a localized oscillation (r=1 cm) on axis to an oscillation of the entire plasma. Also, measurements during the initial startup phase of the discharge show evidence of hollow density profiles. In addition, a simultaneous measurement of the poloidal magnetic field has been developed which provides 20 channels of polarimetry. Interferometry and polarimetry both use the same imaging system and the spatial resolution of both measurements has been tested using plastic and crystal-quartz test objects. The signal-to-noise ratio for the polarimeter has also proved adequate for the expected Faraday rotation angle (alphamax=7°, Ip=70 kA, n=5×10^13 cm^−3)

Highly efficient frequency triplers in the millimeter wave region incorporating a back-to-back configuration of two varactor diodes

This paper reports on the recent development of monolithic frequency tripler array employing a back-to-back configuration of varactor diodes. Even harmonic idler circuits are unnecessary in this design. Furthermore, no external dc bias is required. The arrangement results in highly efficient, easily-fabricated and inexpensive frequency triplers

Millimeter and submillimeter wave technology developments for the next generation of fusion devices

There is increasing demand for compact watt-level coherent sources in the millimeter and submillimeter wave region. The approach that we have taken to satisfy this need is to fabricate two-dimensional grids loaded with oscillators, electronic beam steerers, and frequency multipliers for quasioptical coherent spatial combining of the outputs of a large number of low-power devices

Independent component analysis for the identification of sources of variation on an industrial nirs application

A Near Infrared Spectroscopy (NIRS) industrial application was developed by the LPF-Tagralia team, and transferred to a Spanish dehydrator company (Agrotécnica Extremeña S.L.) for the classification of dehydrator onion bulbs for breeding purposes. The automated operation of the system has allowed the classification of more than one million onion bulbs during seasons 2004 to 2008 (Table 1). The performance achieved by the original model (R2=0,65; SEC=2,28ºBrix) was enough for qualitative classification thanks to the broad range of variation of the initial population (18ºBrix). Nevertheless, a reduction of the classification performance of the model has been observed with the passing of seasons. One of the reasons put forward is the reduction of the range of variation that naturally occurs during a breeding process, the other is the variations in other parameters than the variable of interest but whose effects would probably be affecting the measurements [1]. This study points to the application of Independent Component Analysis (ICA) on this highly variable dataset coming from a NIRS industrial application for the identification of the different sources of variation present through seasons

Identification of a Likely Radio Counterpart of the Rapid Burster

We have identified a likely radio counterpart to the low-mass X-ray binary MXB 1730-335 (the Rapid Burster). The counterpart has shown 8.4 GHz radio on/off behavior correlated with the X-ray on/off behavior as observed by the RXTE/ASM during six VLA observations. The probability of an unrelated, randomly varying background source duplicating this behavior is 1-3% depending on the correlation time scale. The location of the radio source is RA 17h 33m 24.61s; Dec -33d 23' 19.8" (J2000), +/- 0.1". We do not detect 8.4 GHz radio emission coincident with type II (accretion-driven) X-ray bursts. The ratio of radio to X-ray emission during such bursts is constrained to be below the ratio observed during X-ray persistent emission at the 2.9-sigma level. Synchrotron bubble models of the radio emission can provide a reasonable fit to the full data set, collected over several outbursts, assuming that the radio evolution is the same from outburst to outburst, but given the physical constraints the emission is more likely to be due to ~hour-long radio flares such as have been observed from the X-ray binary GRS 1915+105.Comment: 28 pages, 4 figures; accepted for publication in ApJ (no changes

Interferometric fir phase imaging of a tokamak plasma

Multichannel phase imaging of dielectric objects has been demonstrated in the laboratory using a microbolometer detector array and 400 GHz carcinotron radiation cource. The application of this imaging system to perform single shot measurements of electron density profiles in a tokamak plasma is described. The primary advantages are increased spatial resolution together with a much simpler optical system

An XMM-Newton observation of the globular cluster Omega Centauri

We report on a deep XMM-Newton EPIC observation of the globular cluster Omega Cen performed on August 13th, 2001. We have detected 11 and 27 faint X-ray sources in the core and half mass radii, searching down to a luminosity of 1.3 x 10^{31} erg s^{-1} in the 0.5-5 keV range. Most sources have bolometric X-ray luminosities between ~ 10^{31}-10^{32} erg s^{-1}. We present the color-color and hardness-intensity diagrams of the source sample, as well as high-quality EPIC spectra of the brightest objects of the field; including the two candidate Cataclysmic Variables (CVs) in the core and the quiescent neutron star low-mass X-ray binary candidate. The spectra of the latter objects fully support their previous classification. We show that the bulk of sources are hard and spectrally similar to CVs. The lack of soft faint sources might be related to the absence of millisecond pulsars in the cluster. The XMM-Newton observations reveal the presence of an excess of sources well outside the core of the cluster where several RS CVn binaries have already been found. We have also analyzed a publicly available Chandra ACIS-I observation performed on January 24-25th, 2000, to improve the XMM-Newton source positions and to search for source intensity variations between the two data sets. 63 XMM-Newton sources have a Chandra counterpart, and 15 sources within the half-mass radius have shown time variability. Overall, the general properties of the faint X-ray sources in Omega Cen suggest that they are predominantly CVs and active binaries (RS CVn or BY Dra).Comment: 21 pages, 2 color figures, 8 B&W figures. Accepted for publication in Astronomy and Astrophysic

How to Prepare Interprofessional Teams in Two Weeks: An Innovative Education Program Nested in Telehealth

PROBLEM: Preparing health professional students for interprofessional collaborative practice, especially at a distance where provider shortages prevail remains difficult. APPROACH: A two-week interprofessional education (IPE) immersion experience preparing students from 11 disciplines and four universities was implemented. Week-one, using online technology, students develop/present an interprofessional careplan for a complex patient. Students then meet face-to-face to conduct group interviews with two standardized patient dyads. Week-two, students develop a website for use of the patient dyads. Websites are presented to faculty and fellow students via an online virtual meeting space. OUTCOMES: To date, 594 students have participated demonstrating capacity to: 1.effectively engage in interprofessional care,  2. utilize Telehealth to impact care and break down barriers of isolation, and 3. implement skills to advance healthcare. CONCLUSION: IPE combined with Telehealth technology provides future providers with knowledge and skills for interprofessional care regardless of geographic barriers. Next Step: Integrate more technology using mobile devices and enhance the evaluation process

A 23 GHz Survey of GRB Error Boxes

The Haystack 37-meter telescope was used in a pilot project in May 1995 to observe GRB error boxes at 23~GHz. Seven BATSE error boxes and two IPN arcs were scanned by driving the beam of the telescope rapidly across their area. For the BATSE error boxes, the radio observations took place two to eighteen days after the BATSE detection, and several boxes were observed more than once. Total power data were recorded continuously as the telescope was driven at a rate of 0.2~degrees/second, yielding Nyquist sampling of the beam with an integration time of 50~milliseconds, corresponding to a theoretical rms sensitivity of 0.5~Jy. Under conditions of good weather, this sensitivity was achieved. In a preliminary analysis of the data we detect only two sources, 3C273 and 0552+398, both catalogued sources that are known to be variable at 23~GHz. Neither had a flux density that was unusally high or low at the time of our observations.Comment: 5 pages, 1 postscript figure. To appear in Proceedings of the Third Huntsville Symposium on Gamma-Ray Bursts (eds. C. Kouveliotou, M. S. Briggs, and G. J. Fishman