10,096 research outputs found
Four new Aphodius Illiger from pocket gopher burrows in Arizona, Utah, Kansas and Nebraska (Coleoptera: Scarabaeidae: Aphodiinae)
We describe four new species of winter-active Aphodius (sensu lato) from pocket gopher burrows in Arizona, Utah, Kansas, and Nebraska: A. cacabatus, A. paulseni, A. skillmani, and A. utopensis. Diagnostic characters of all four species are illustrated
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X-rays from cataclysmic variables
Cataclysmic Variables are a distinct class of interacting binaries, transferring mass from a donor star to a degenerate accretor, a white dwarf. We here review X-ray observations of these systems, with some emphasis on what has been achieved in the last decade
Laser ablated high T(sub c) superconducting thin YBa2Cu3O(7-x) films on substrates suitable for microwave applications
The development of high temperature superconducting YBa2Cu3O(7-x) thin films on substrates suitable for microwave applications is of great interest for evaluating their applications for space radar, communication, and sensor systems. Thin films of YBa2Cu3O(7-x) were formed on SrTiO3, ZrO2, MgO, and LaAlO3 substrates by laser ablation. The wavelength used was 248 nm from a KrF excimer laser. During deposition the films were heated to 600 C in a flowing oxygen environment, and required no post annealing. The low substrate temperature during deposition with no post annealing gave films which were smooth, which had their c-axis aligned to the substrates, and which had grains ranging from 0.2 to 0.5 microns in size. The films being c-axis aligned gave excellent surface resistance at 35 GHz which was lower than that of copper at 77 K. At present, LaAlO3 substrates with a dielectric constant of 22, appears suitable as a substrate for microwave and electronic applications. The films were characterized by resistance-temperature measurements, scanning electron microscopy, and x ray diffraction. The highest critical transition temperatures (T sub c) are above 89 K for films on SrTiO3 and LaAlO3, above 88 K for ZrO2, and above 86 K for MgO. The critical current density (J sub c) of the films on SrTiO3 is above 2 x 10(exp 6) amperes/sq cm at 77 K. The T(sub c) and J(sub c) are reported as a function of laser power, composition of the substrate, and temperature of the substrate during deposition
High Speed Photometry of SDSS J013701.06-091234.9
We present high speed photometry of the Sloan Digital Sky Survey cataclysmic
variable SDSS J013701.06-091234.9 in quiescence and during its 2003 December
superoutburst. The orbital modulation at 79.71\pm0.01 min is double humped; the
superhump period is 81.702\pm0.007 min. Towards the end of the outburst late
superhumps with a period of 81.29\pm0.01 min were observed. We argue that this
is a system of very low mass transfer rate, and that it probably has a long
outburst interval.Comment: 5 pages, 8 figures. Accepted for publication in MNRA
Dwarf Nova Oscillations and Quasi-Periodic Oscillations in Cataclysmic Variables - VIII. VW Hyi in outburst observed with the Southern African Large Telescope
We analyse four light curves obtained at high time resolution (~ 0.1 s) with
the 11-m Southern African Large Telescope, at the ends of two normal outbursts
and one superoutburst of the dwarf nova VW Hyi. All of these contain at least
some Dwarf Nova Oscillations (DNOs), which, when at their highest amplitudes,
are seen in unprecedented detail. In addition to the expected DNOs with periods
> 20 s we find a previously unknown modulation at 13.39 s, but none at shorter
periods. The various DNOs and their interaction with the longer period
Quasi-periodic Oscillations are interpreted in terms of the model of
magnetically controlled flow from an accretion disc proposed earlier in this
series of papers. Our observations include rare DNOs very late in outburst; we
find that the fundamental period does not increase beyond ~ 90 s, which is the
same value that the independent ``longer period DNOs'' converge on.Comment: Accepted for publication in MNRAS. 7 pages, 10 figures, 2 table
The white dwarf in dwarf nova SDSS J080434.20+510349.2: Entering the instability strip?
SDSS J080434.20+510349.2 is the WZ type binary that displayed rare outburst
in 2006 (Pavlenko et al., 2007). During the long-lasting tail of the late stage
of the outburst binary shown the two-humped or four-humped profile of the
orbital light modulation. The amplitude of orbital light curve decreased while
the mean brightness decreased, more over that occurred 10 times faster
during the fast outburst decline in respect to the late quiet state of slow
outburst fading. There were no white dwarf pulsations detected neither 1 - 1.5
months prior to the outburst nor in 1.5 - 2 months after the 2006 outburst in
this system. However the strong non-radial pulsations with period 12.6 minutes
and mean amplitude of 0.05^m were first detected in V band with 2.6-m Shajn
mirror telescope of the Crimean astrophysical observatory in ~ 8 months after
the outburst. The evolution of pulsations over two years in 2006 - 2008 is
considered. It is supposed that pulsations first appeared when the cooling
white dwarf (after the outburst) entered the instability strip although the
possibility of temporary lack of pulsations at some occasions also could not be
excluded.Comment: Submitted to Proceedings of 16th European White Dwarf Workshop
(EUROWD08
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Laser ablative cutting of ceramics for electronics applications
Pulsed, high-beam quality lasers offer unique materials processing characteristics. In processing metals, copper vapor and pulsed Nd:YAG lasers have produced micron-scale cuts and holes with submicron heat-affected zones. Since the cost of laser photons is high and average material removal rates can be slow with ablation, high value-added applications are necessary to justify processing costs. Ceramics present a special challenge for manufacturing because of their high hardness, relatively low thermal conductivity, and brittle nature. Surface damage typically limits the strength of a ceramic part to a small fraction of its bulk strength. This work investigates the use of copper vapor and pulsed diode-pumped Nd:YAG lasers to cut precision features in ceramic substrates. Variations in laser wavelength and power, processing speed, ceramic type, and assist gas were investigated with the goal of producing <100-{mu}m wide by 600-{mu}m deep cuts through silicon-carbide and alumina/titanium-carbide substrates for potential use in electronics. Silicon-carbide bars 250-{mu}m wide by 600-{mu}m high by 2.5-cm long were laser cut from substrates without fracture
Service-based survey of dystonia in Munich
We performed a service-based epidemiological study of dystonia in Munich, Germany. Due to favourable referral and treatment patterns in the Munich area, we could provide confident data from dystonia patients seeking botulinum toxin treatment. A total of 230 patients were ascertained, of whom 188 had primary dystonia. Point prevalence ratios were estimated to be 10.1 (95% confidence interval 8.4-11.9) per 100,000 for focal and 0.3 (0.0-0.6) for generalised primary dystonia. The most common focal primary dystonias were cervical dystonia with 5.4 (4.2-6.7) and essential blepharospasm with 3.1 (2.1-4.1) per 100,000 followed by laryngeal dystonia (spasmodic dysphonia) with 1.0 (0.4-1.5) per 100,000. Copyright (C) 2002 S. Karger AG, Base
A warped disk model for M33 and the 21-cm line width in spiral galaxies
To determine the actual HI distribution and the velocity field in the
outermost disk of the spiral galaxy M33, a tilted-ring model is fitted to 21-cm
line data taken with the Arecibo Telescope. Since M33 is one of the main
calibrators for the extragalactic distance scale derived through the
Tully-Fisher relation, the outer disk warping is of interest for a correct
determination and deprojection of the galaxy's line width. Even though our best
model predicts small effects on the observed line width of M33, we show that
similar outer disk warping in galaxies oriented differently along our line of
sight could affect the widths considerably. Therefore there may be systematic
effects in the determination of the rotation velocities and dynamic masses of
spiral galaxies, whose exact value depends also on which method is used for
measuring the galaxy's total line width.Comment: 27 pages, ps files only, ApJ in pres
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