1,752 research outputs found
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
Assessing the Origin of Noise in the Precipitation Gauge Geonor T-200B
The Geonor T-200B is an all-weather precipitation gauge utilized by the Research Applications Laboratory (RAL) under the University Corporation for Atmospheric Research (UCAR) and the National Center for Atmospheric Research (NCAR). RAL has been dealing with a persistent issue of noise within the Geonor Devices during non-precipitation events. When there is not precipitation occurring, the data reading off the Geonor would be expected to be a constant value, as no precipitation is being collected. However, the device is producing unaccounted variation (noise) causing tremor like lines to appear in the data. The noise in the data is an issue for RAL because it makes it complicated to pinpoint the exact beginning and end of a precipitation event. Many airports use the Geonor sensors to predict unsafe flying conditions. Being able to pinpoint the beginning and ending weather patterns during storms would lead to more accurate and efficient airport scheduling. To isolate the source of the undesired noise two correlation experiments were run on the Geonor gauges. The experiments were conducted at the NCAR Marshal Field test site. The first test was to understand the effect of temperature change on the noise. The second test provided assess the effect of electrical interference on the noise in the device. The change in temperature correlated 63% to a change in frequency from the Geonor. The electrical interference test provided a reduction of variation in the frequency by two hertz. From the result of the study it can be stated that a change in temperature has a great effect on the noise from the Geonor and causes diurnal variation in the data. The electrical interference test showed promising results as a possible origin of the noise. Further experiments should be conducted to prove that adding an electrical shield reduces the noise within the device. Another source of noise to asses in further experiments would be the effect of temperature on the electrical panel that collects the data
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
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
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
Psychosocial Adjustment, Health-Related Quality of Life, and Psychosexual Development of Boys with Hypospadias: A Systematic Review
ObjectiveâA systematic review of studies on psychosocial adjustment, HRQoL (health-related quality of life), and psychosexual development of boys with hypospadias.âMethodsâResearch 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.âResultsâThirteen 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.âConclusionsâThe identification of psychosocial risk factors in methodologically sound studies is necessary to guarantee a comprehensive treatment for boys with hypospadia
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&
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
Lattice diffusion and surface segregation of B during growth of SiGe heterostructures by molecular beam epitaxy: effect of Ge concentration and biaxial stress
Si1-xGex/Si1-yGey/Si(100) heterostructures grown by Molecular Beam Epitaxy
(MBE) were used in order to study B surface segregation during growth and B
lattice diffusion. Ge concentration and stress effects were separated. Analysis
of B segregation during growth shows that: i) for layers in epitaxy on
(100)Si), B segregation decreases with increasing Ge concentration, i.e. with
increased compressive stress, ii) for unstressed layers, B segregation
increases with Ge concentration, iii) at constant Ge concentration, B
segregation increases for layers in tension and decreases for layers in
compression. The contrasting behaviors observed as a function of Ge
concentration in compressively stressed and unstressed layers can be explained
by an increase of the equilibrium segregation driving force induced by Ge
additions and an increase of near-surface diffusion in compressively stressed
layers. Analysis of lattice diffusion shows that: i) in unstressed layers, B
lattice diffusion coefficient decreases with increasing Ge concentration, ii)
at constant Ge concentration, the diffusion coefficient of B decreases with
compressive biaxial stress and increases with tensile biaxial stress, iii) the
volume of activation of B diffusion () is positive for biaxial stress while it
is negative in the case of hydrostatic pressure. This confirms that under a
biaxial stress the activation volume is reduced to the relaxation volume
Unveiling the nature of three INTEGRAL sources through optical spectroscopy
The results of an optical spectroscopy campaign performed at the Astronomical
Observatory of Bologna in Loiano (Italy) on three hard X-ray sources detected
by INTEGRAL (IGR J17303-0601, IGR J18027-1455 and IGR J21247+5058) are
presented. These data have allowed a determination of the nature for two of
them, with IGR J17303-0601 being a low mass X-ray binary in the Galaxy and IGR
J18027-1455 a background Type 1 Seyfert galaxy at redshift z = 0.035. IGR
J21247+5058, instead, has a quite puzzling spectroscopic appearance, with a
broad, redshifted H_alpha complex superimposed onto a `normal' F/G-type
Galactic star continuum: these features, together with the spatially coincident
extended radio emission, might suggest a chance alignment between a relatively
nearby star and a background radio galaxy. These results underline the still
non-negligible importance of smaller telescopes in modern astrophysics.Comment: 4 pages, 2 figures. Accepted for publication in A&A Letter
- âŠ