1,913 research outputs found
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
Neutrinos and Energetics of the Earth
We estimate terrestrial antineutrino and neutrino fluxes according to
different models of Earth composition. We find large variations, corresponding
to uncertainties on the estimated , and abundances in the mantle.
Information on the mantle composition can be derived from antineutrino flux
measurements after subtracting the crust contribution. This requires a good
description of the crust composition in the region of the detector site.
Measurements of terrestrial antineutrinos will provide a direct insight on the
main sources of Earth's heat flow.Comment: 11 pages, RevTeX file. To appear on Phys. Lett. B. Addendum contains
comparison with KamLAND result
Psychosocial Adjustment, Health-Related Quality of Life, and Psychosexual Development of Boys with Hypospadias: A Systematic Review
Objective A systematic review of studies on psychosocial adjustment, HRQoL (health-related quality of life), and psychosexual development of boys with hypospadias. Methods Research was conducted on several online bibliographic databases. Articles were selected on the basis of predefined criteria. Methodological quality was assessed by two independent reviewers who applied a standardized checklist. When possible, data analyses were performed by calculating effect sizes. Results Thirteen studies met the criteria for inclusion, whose methodological standard ranged from low to high quality. None of them has focused on HRQoL. Findings with regard to psychosocial and psychosexual adjustment were inconsistent, though they clearly showed that boys with hypospadias suffer from negative genital appraisal and sexual inhibitions. Overall, medical factors exerted a rather small influence. Psychosocial risk factors have hardly been examined so far. Conclusions The identification of psychosocial risk factors in methodologically sound studies is necessary to guarantee a comprehensive treatment for boys with hypospadia
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
A photometric study of the young open cluster NGC 1220
We present UBV CCD observations obtained in the field of the northern open
cluster NGC 1220, for which little information is available. We provide also BV
CCD photometry of a field 5 northward of NGC 1220 to take into
account field star contamination. We argue that NGC 1220 is a young compact
open cluster, for which we estimate a core radius in the range
arcmin. We identify 26 likely candidate members with spectral type earlier than
, down to =15.00 mag on the basis of the position in the two-colour
Diagram and in the Colour Magnitude Diagrams (CMDs). By analyzing the
distribution of these stars in the colour-colour and CMDs, we find that NGC
1220 has a reddening E mag, is placed pc
distant from the Sun, and has an age of about 60 Myrs. The cluster turns out to
be located about 120 pc above the Galactic plane, relatively high with respect
to its age.Comment: 7 pages, 8 eps figures, accepted for publication in A&
Cepheid and Tip of the Red Giant Branch Distances To the Dwarf Irregular Galaxy IC10
We present color-magnitude diagrams and luminosity functions of stars in the
nearby galaxy IC 10, based on VI CCD photometry acquired with the COSMIC
prime-focus camera on the Palomar 5m telescope. The apparent I-band luminosity
function of stars in the halo of IC 10 shows an identifiable rise at I~21.7
mag. This is interpreted as being the tip of the red giant branch (TRGB) at
M_V~-4 mag. Since IC 10 is at a very low Galactic latitude, its foreground
extinction is expected to be high and the uncertainty associated with that
correction is the largest contributor to the error associated with its distance
determination. Multi-wavelength observations of Cepheid variable stars in IC 10
give a Population I distance modulus of 24.1 +- 0.2 mag, which corresponds to a
linear distance of 660 +- 66 kpc for a total line-of-sight reddening of E(B-V)
= 1.16 +- 0.08 mag, derived self-consistently from the Cepheid data alone.
Applying this Population I reddening to the Population II halo stars gives a
TRGB distance modulus of 23.5 +- 0.2 mag, corresponding to 500 +- 50 kpc. We
consider this to be a lower limit on the TRGB distance. Reconciling the Cepheid
and TRGB distances would require that the reddening to the halo is
E(B-V) = 0.31 mag lower than that into the main body of the galaxy.
This then suggests that the Galactic extinction in the direction of IC10 is
(B-V) ~ 0.85
Discovery of a bright eclipsing cataclysmic variable
We report on the discovery of J0644+3344, a bright deeply eclipsing
cataclysmic variable (CV) binary. Spectral signatures of both binary components
and an accretion disk can be seen at optical wavelengths. The optical spectrum
shows broad H I, He I, and He II accretion disk emission lines with deep narrow
absorption components from H I, He I, Mg II and Ca II. The absorption lines are
seen throughout the orbital period, disappearing only during primary eclipse.
These absorption lines are either the the result of an optically-thick inner
accretion disk or from the photosphere of the primary star. Radial velocity
measurements show that the H I, He I, and Mg II absorption lines phase with the
the primary star, while weak absorption features in the continuum phase with
the secondary star. Radial velocity solutions give a 150+/-4 km/s
semi-amplitude for the primary star and 192.8+/-5.6 km/s for the secondary. The
individual stellar masses are 0.63-0.69 Mdot for the primary and 0.49-0.54 Mdot
for the secondary. The bright eclipsing nature of this binary has helped
provide masses for both components with an accuracy rarely achieved for CVs.
This binary most closely resembles a nova-like UX UMa or SW Sex type of CV.
J0644+3344, however, has a longer orbital period than most UX UMa or SW Sex
stars. Assuming an evolution toward shorter orbital periods, J0644+3344 is
therefore likely to be a young interacting binary. The secondary star is
consistent with the size and spectral type of a K8 star, but has an M0 mass.Comment: 10 pages, 13 figure, accepted for publication in A&
BVRIJK light curves and radial velocity curves for selected Magellanic Cloud Cepheids
We present high precision and well sampled BVRIJK light curves and radial
velocity curves for a sample of five Cepheids in the SMC. In addition we
present radial velocity curves for three Cepheids in the LMC. The low
metallicity (Fe/H ~ -0.7) SMC stars have been selected for use in a
Baade-Wesselink type analysis to constrain the metallicity effect on the
Cepheid Period-Luminosity relation. The stars have periods of around 15 days so
they are similar to the Cepheids observed by the Extragalactic Distance Scale
Key Project on the Hubble Space Telescope. We show that the stars are
representative of the SMC Cepheid population at that period and thus will
provide a good sample for the proposed analysis. The actual Baade-Wesselink
analysis are presented in a companion paper.Comment: Accepted for publication in A&A, 23 pages, 10 figures, data tables
will be made available electronically from the CD
SN1997cy/GRB970514 - A New Piece in the GRB Puzzle?
We present observations of SN1997cy, a supernova discovered as part of the
Mount Stromlo Abell Cluster SN Search, which does not easily fit into the
traditional classification scheme for supernovae. This object's extraordinary
optical properties and coincidence with GRB970514, a short duration gamma ray
burst, suggest a second case, after SN1998bw/GRB980425, for a SN-GRB
association. SN1997cy is among the most luminous SNe yet discovered and has a
peculiar spectrum. We present evidence that SN1997cy ejected approximately 2
solar masses of 56Ni, supported by its late-time light curve, and FeII/[FeIII]
lines in its spectrum, although it is possible that both these observations can
be explained via circumstellar interaction. While SN1998bw and SN1997cy appear
to be very different objects with respect to both their gamma ray and optical
properties, SN1997cy and the optical transient associated with GRB970508 have
roughly similar late-time optical behavior. This similarity may indicate that
the late-time optical output of these two intrinsically bright transient events
have a common physical process. Although the connection between GRB970514 and
SN1997cy is suggestive, it is not conclusive. However, if this association is
real, followup of short duration GRBs detected with BATSE or HETE2 should
reveal objects similar to SN1997cy.Comment: 26 pages including 6 postscript figures and 3 tables. Submitted to
ApJ. Re-calibrated photometry - objects are about 0.3mags brighter than in
original versio
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
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