1,330 research outputs found
Advances in Calibration and Imaging Techniques in Radio Interferometry
This paper summarizes some of the major calibration and image reconstruction
techniques used in radio interferometry and describes them in a common
mathematical framework. The use of this framework has a number of benefits,
ranging from clarification of the fundamentals, use of standard numerical
optimization techniques, and generalization or specialization to new
algorithms
A multi-scale multi-frequency deconvolution algorithm for synthesis imaging in radio interferometry
Aims : We describe MS-MFS, a multi-scale multi-frequency deconvolution
algorithm for wide-band synthesis-imaging, and present imaging results that
illustrate the capabilities of the algorithm and the conditions under which it
is feasible and gives accurate results.
Methods : The MS-MFS algorithm models the wide-band sky-brightness
distribution as a linear combination of spatial and spectral basis functions,
and performs image-reconstruction by combining a linear-least-squares approach
with iterative minimization. This method extends and combines the
ideas used in the MS-CLEAN and MF-CLEAN algorithms for multi-scale and
multi-frequency deconvolution respectively, and can be used in conjunction with
existing wide-field imaging algorithms. We also discuss a simpler hybrid of
spectral-line and continuum imaging methods and point out situations where it
may suffice.
Results : We show via simulations and application to multi-frequency VLA data
and wideband EVLA data, that it is possible to reconstruct both spatial and
spectral structure of compact and extended emission at the continuum
sensitivity level and at the angular resolution allowed by the highest sampled
frequency.Comment: 17 pages, 11 figure
Hubungan Karakteristik Ibu Dengan Pemberian Susu Pada Bayi Usia 0-6 Bulan Di Wilayah Kerja Puskesmas Mabelopura Palu
Bayi yang diberi susu formula memiliki kemungkinan 25 kali lebih tinggi untuk meninggal dunia pada bulan pertama kelahirannya dibandingkan dengan bayi yang disusui oleh ibunya secara eksklusif. Selama tiga tahun berturut-turut, cakupan pemberian ASI eksklusif Puskesmas Mabelopura berada pada tiga terendah di Kota Palu dengan persentasi sebesar 34,47% untuk tahun 2011, 36,73% untuk tahun 2012 dan 31,30% untuk tahun 2013. Penelitian ini bertujuan untuk mengetahui hubungan karakteristik ibu (Umur, Tingkat Pendidikan, Pengetahuan dan Status Pekerjaan) dengan pemberian susu formula pada bayi usia 0-6 bulan di Wilayah Kerja Puskesmas Mabelopura Palu. Penelitian ini menggunakan desain rancangan cross sectional. Sampel dalam penelitian ini adalah sebagian ibu yang memiliki bayi usia 6-12 bulan sebanyak 70 orang yang diambil secara Non Random Sampling dengan teknik purposive sampling. Hasil penelitian diperoleh dengan wawancara menggunakan kuesioner, dianalisis dengan uji Chi-square, pada batas kemaknaan (alfa 0,05). Hasil penelitian yaitu Umur ibu (ρ = 0,024), Pengetahuan (ρ = 0,005), dan Status Pekerjaan (ρ = 0,016) berhubungan dengan pemberian susu formula pada bayi usia 0-6 bulan, sedangkan Tingkat Pendidikan (ρ = 0,710) tidak berhubungan dengan pemberian susu formula pada bayi usia 0-6 bulan. Perlunya program edukasi bagi ibu tentang pentingnya pemberian ASI secara eksklusif serta kerja sama masyarakat dengan petugas kesehatan untuk meningkatkan cakupan pemberian ASI Eksklusif dan meregulasi susu formula
Efimov states and their Fano resonances in a neutron-rich nucleus
Asymmetric resonances in elastic n+C scattering are attributed to
Efimov states of such neutron-rich nuclei, that is, three-body bound states of
the n+n+C system when none of the pairs is bound or some of them only
weakly bound. By fitting to the general resonance shape described by Fano, we
extract resonance position, width, and the "Fano profile index". While Efimov
states have been discussed extensively in many areas of physics, there is only
one very recent experimental observation in trimers of cesium atoms. The
conjunction that we present of the Efimov and Fano phenomena may lead to
experimental realization in nuclei.Comment: 4 double-column pages, 3 figure
Spitzer Observations of the New Luminous Red Nova M85OT2006-1
M85OT2006-1 is the latest and most brilliant addition to the small group of
known Luminous Red Novae (LRNe). An identifying characteristic of the
previously detected events (M31 RV, V4322 Sgr & V838 Mon) was a spectral
red-ward evolution connected with an emerging infrared component following the
optical decay. Here we report on the discovery of a similar feature in
Keck/NIRC and Spitzer photometry of M85OT2006-1 six months post-eruption. We
find that its 2.1-22 micrometer spectral energy distribution is best described
by a black body with effective temperature T_eff=950+-150 K and bolometric
luminosity L=2.9+-0.5x10^5 L_sun. Assuming spherical geometry, the black body
effective radius, R=2.0+-0.5x10^4 R_sun, and corresponding expansion velocity,
v=870+-260 km/s, are remarkably similar to the properties of M31 RV 70 days
after its eruption. Furthermore, we propose a search strategy for LRNe in the
local Universe making use of the longevity of their infrared excess emission
and discuss the expected number of events in the Spitzer Infrared Nearby
Galaxies Survey.Comment: manuscript after minor revisions, accepted for Ap
Определение эффективности нейтронного детектора из пластического сцинтиллятора o100?200 мм
Рассчитывается и экспериментально проверяется эффективность детектора. к нейтронам сверхвысоких (десятки и сотни МэВ) энергий
Alternative Fourier Expansions for Inverse Square Law Forces
Few-body problems involving Coulomb or gravitational interactions between
pairs of particles, whether in classical or quantum physics, are generally
handled through a standard multipole expansion of the two-body potentials. We
discuss an alternative based on a compact, cylindrical Green's function
expansion that should have wide applicability throughout physics. Two-electron
"direct" and "exchange" integrals in many-electron quantum systems are
evaluated to illustrate the procedure which is more compact than the standard
one using Wigner coefficients and Slater integrals.Comment: 10 pages, latex/Revtex4, 1 figure
Structural and Magnetic Properties of Trigonal Iron
First principles calculations of the electronic structure of trigonal iron
were performed using density function theory. The results are used to predict
lattice spacings, magnetic moments and elastic properties; these are in good
agreement with experiment for both the bcc and fcc structures. We find however,
that in extracting these quantities great care must be taken in interpreting
numerical fits to the calculated total energies. In addition, the results for
bulk iron give insight into the properties of thin iron films. Thin films grown
on substrates with mismatched lattice constants often have non-cubic symmetry.
If they are thicker than a few monolayers their electronic structure is similar
to a bulk material with an appropriately distorted geometry, as in our trigonal
calculations. We recast our bulk results in terms of an iron film grown on the
(111) surface of an fcc substrate, and find the predicted strain energies and
moments accurately reflect the trends for iron growth on a variety of
substrates.Comment: 11 pages, RevTeX,4 tar'd,compressed, uuencoded Postscript figure
Near-field optical microscopy and spectroscopy of one-dimensional metallic photonic crystal slabs
Production in Peripheral Heavy-Ion Collisions
We estimate the impact parameter dependence of the production cross section
for and mesons in peripheral heavy-ion collisions collisions.
Total and elastic cross sections are calculated in an equivalent
photon approximation.Comment: 9 pages, uuencoded postscrip
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