2,473 research outputs found
NGC 6738: not a real open cluster
A photometric, astrometric and spectroscopic investigation of the poorly
studied open cluster NGC 6738 has been performed in order to ascertain its real
nature. NGC 6738 is definitely not a physical stellar ensemble: photometry does
not show a defined mean sequence, proper motions and radial velocities are
randomly distributed, spectro-photometric parallaxes range between 10 and 1600
pc, and the apparent luminosity function is identical to that of the
surrounding field. NGC 6738 therefore appears to be an apparent concentration
of a few bright stars projected on patchy background absorption.Comment: A&A, in press (compared with first submission to astro-ph, now Table
2 and Figure 4 are replaced with corrected versions
II Zwicky 23 and Family
II Zwicky 23 (UGC 3179) is a luminous, nearby compact narrow emission line
starburst galaxy with blue optical colors and strong emission lines. We present
a photometric and morphological study of II Zw 23 and its interacting
companions using data obtained with the WIYN 3.5-m telescope in Kitt Peak,
Arizona. II Zwicky 23 has a highly disturbed outer structure with long trails
of debris that may be feeding tidal dwarfs. Its central regions appear disky, a
structure that is consistent with the overall rotation pattern observed in the
H-alpha velocity field measured from Densepak observations obtained with WIYN.
We discuss the structure of II Zwicky 23 and its set of companions and possible
scenarios of debris formation in this system.Comment: 5 pages, 2 figures. To appear in the proceedings of ESO Astrophysics
Symposia: "Groups of Galaxies in the Nearby Universe", eds. I. Saviane, V.
Ivanov, J. Burissova (Springer
Die psychosoziale/-sexuelle Entwicklung von Knaben mit einer Hypospadie
Zusammenfassung: Knaben mit einer Hypospadie sind spezifischen psychischen Belastungen im Zusammenhang mit dem chirurgischen Eingriff im Genitalbereich und einem kosmetisch und/oder funktionell beeinträchtigten Penis ausgesetzt. Während in den letzten Jahrzehnten intensive Anstrengungen zur Verbesserung der Operationstechniken unternommen worden sind, wurde die psychosoziale und psychosexuelle Entwicklung von Kindern und Jugendlichen nach Hypospadiekorrektur erst selten untersucht. Die Resultate der wenigen Studien sind insgesamt sehr widersprüchlich. Sie weisen aber auch deutlich daraufhin, dass die betroffenen Knaben unter spezifischen Problemen wie dem andersartigen Aussehen ihres Penis leiden. Das Angebot von medizinischen Verlaufskontrollen und psychosozialer Beratung muss ihnen deshalb bis ins junge Erwachsenenalter zur Verfügung gestellt werden. Für die zukünftige Forschung gilt es, in methodisch fundierten Studien Lebensqualität und Entwicklung der Knaben systematisch zu untersuchen. Dabei müssen insbesondere psychosoziale Risikofaktoren identifiziert werde
Photometric Calibration of the Supernova Legacy Survey Fields
We present the photometric calibration of the Supernova Legacy Survey (SNLS)
fields. The SNLS aims at measuring the distances to SNe Ia at (0.3<z<1) using
MegaCam, the 1 deg^2 imager on the Canada-France-Hawaii Telescope (CFHT). The
uncertainty affecting the photometric calibration of the survey dominates the
systematic uncertainty of the key measurement of the survey, namely the dark
energy equation of state. The photometric calibration of the SNLS requires
obtaining a uniform response across the imager, calibrating the science field
stars in each survey band (SDSS-like ugriz bands) with respect to standards
with known flux in the same bands, and binding the calibration to the UBVRI
Landolt standards used to calibrate the nearby SNe from the literature
necessary to produce cosmological constraints. The spatial non-uniformities of
the imager photometric response are mapped using dithered observations of dense
stellar fields. Photometric zero-points against Landolt standards are obtained.
The linearity of the instrument is studied. We show that the imager filters and
photometric response are not uniform and publish correction maps. We present
models of the effective passbands of the instrument as a function of the
position on the focal plane. We define a natural magnitude system for MegaCam.
We show that the systematics affecting the magnitude-to-flux relations can be
reduced if we use the spectrophotometric standard star BD +17 4708 instead of
Vega as a fundamental flux standard. We publish ugriz catalogs of tertiary
standards for all the SNLS fields.Comment: 46 pages, 23 figures. Accepted by Astronomy and Astrophysics. Online
material available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr
(130.79.128.5) or http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ or
alternatively from: http://supernovae.in2p3.fr/snls3/regnault09_cds.tar.g
Huge Seebeck coefficients in non-aqueous electrolytes
The Seeebeck coefficients of the non-aqueous electrolytes tetrabutylammonium
nitrate, tetraoctylphosphonium bromide and tetradodecylammonium nitrate in
1-octanol, 1-dodecanol and ethylene-glycol are measured in a temperature range
from T=30 to T=45 C. The Seebeck coefficient is generally of the order of a few
hundreds of microvolts per Kelvin for aqueous solution of inorganic ions. Here
we report huge values of 7 mV/K at 0.1M concentration for tetrabutylammonium
nitrate in 1-dodecanol. These striking results open the question of
unexpectedly large kosmotrope or "structure making" effects of
tetraalkylammonium ions on the structure of alcohols.Comment: Submitted to J. Chem. Phy
Magnetic properties of HO2 thin films
We report on the magnetic and transport studies of hafnium oxide thin films
grown by pulsed-laser deposition on sapphire substrates under different oxygen
pressures, ranging from 10-7 to 10-1 mbar. Some physical properties of these
thin films appear to depend on the oxygen pressure during growth: the film
grown at low oxygen pressure (P ~= 10-7 mbar) has a metallic aspect and is
conducting, with a positive Hall signal, while those grown under higher oxygen
pressures (7 x 10-5 <= P <= 0.4 mbar) are insulating. However, no intrinsic
ferromagnetic signal could be attributed to the HfO2 films, irrespective of the
oxygen pressure during the deposition.Comment: 1
Followup Observations of SDSS and CRTS Candidate Cataclysmic Variables
We present photometry of 11 and spectroscopy of 35 potential cataclysmic
variables from the Sloan Digital Sky Survey, the Catalina Real-Time Transient
Survey and vsnet-alerts. The photometry results include quasi-periodic
oscillations during the decline of V1363 Cyg, nightly accretion changes in the
likely Polar (AM Herculis binary) SDSS J1344+20, eclipses in SDSS J2141+05 with
an orbital period of 76+/-2 min, and possible eclipses in SDSS J2158+09 at an
orbital period near 100 min. Time-resolved spectra reveal short orbital periods
near 80 min for SDSS J0206+20, 85 min for SDSS J1502+33, and near 100 min for
CSS J0015+26, RXS J0150+37, SDSS J1132+62, SDSS J2154+15 and SDSS J2158+09. The
prominent HeII line and velocity amplitude of SDSS J2154+15 are consistent with
a Polar nature for this object, while the lack of this line and a low velocity
amplitude argue against this classification for RXS J0150+37. Single spectra of
10 objects were obtained near outburst and the rest near quiescence, confirming
the dwarf novae nature of these objects.Comment: 34 pages, 14 figures, in press at A
The Discovery and Broad-band Follow-up of the Transient Afterglow of GRB 980703
We report on the discovery of the radio, infrared and optical transient
coincident with an X-ray transient proposed to be the afterglow of GRB 980703.
At later times when the transient has faded below detection, we see an
underlying galaxy with R=22.6; this galaxy is the brightest host galaxy (by
nearly 2 magnitudes) of any cosmological GRB thus far. In keeping with an
established trend, the GRB is not significantly offset from the host galaxy.
Interpreting the multi-wavelength data in the framework of the popular fireball
model requires that the synchrotron cooling break was between the optical and
X-ray bands on July 8.5 UT and that the intrinsic extinction of the transient
is Av=0.9. This is somewhat higher than the extinction for the galaxy as a
whole, as estimated from spectroscopy.Comment: 5 pages, 3 figures, and 2 tables. Submitted to the Astrophysical
Journal Letters on 27 August 199
Atomic layer deposition of ZnS nanotubes
We report on growth of high-aspect-ratio () zinc sulfide
nanotubes with variable, precisely tunable, wall thicknesses and tube diameters
into highly ordered pores of anodic alumina templates by atomic layer
deposition (ALD) at temperatures as low as 75 C. Various
characterization techniques are employed to gain information on the
composition, morphology, and crystal structure of the synthesized samples.
Besides practical applications, the ALD-grown tubes could be envisaged as model
systems for the study of a certain class of size-dependent quantum and
classical phenomena.Comment: 1 LaTeX source file, 8 eps figures, and the manuscript in PDF forma
Is there an ideal age for hypospadias repair? A pilot study
OBJECTIVE: To assess whether repairing hypospadias before or after 18 months affects psychological adjustment, health-related quality of life (HRQoL) and surgical outcome. PATIENTS AND METHODS: Seventy-seven boys aged 6-17 years were assigned to one of two groups, according to whether they had a hypospadias repair before or after the age of 18 months. The surgical outcome was assessed using the pediatric penile perception score by non-involved urologists. A psychologist interviewed the patients to assess HRQoL and gender-role behavior. The child's psychological adjustment was assessed with a questionnaire for parents. RESULTS: The surgical outcome and complication rate were not significantly different between groups. A covariance analysis of HRQoL, gender-role behavior and psychological adjustment as a function of age at the last operation with current age as covariant was performed, but differences did not reach significance. CONCLUSION: This study does not provide evidence to support recommendations concerning the ideal age for hypospadias repair. In the absence of evidence of a benefit of early surgery, anesthesia-related risk factors must be considered when operating in very early infancy. Large, prospective studies, measuring surgical and psychological outcome with similar instruments to those presented may reveal whether there is a true ideal age for hypospadias surgery
- …