620 research outputs found
The ATLAS-SPT Radio Survey of Cluster Galaxies
Using a high-performance computing cluster to mosaic 4,787 pointings, we have
imaged the 100 sq. deg. South Pole Telescope (SPT) deep-field at 2.1 GHz using
the Australian Telescope Compact Array to an rms of 80 Jy and a resolution
of 8". Our goal is to generate an independent sample of radio-selected galaxy
clusters to study how the radio properties compare with cluster properties at
other wavelengths, over a wide range of redshifts in order to construct a
timeline of their evolution out to . A preliminary analysis of the
source catalogue suggests there is no spatial correlation between the clusters
identified in the SPT-SZ catalogue and our wide-angle tail galaxies.Comment: 9 pages, 4 figures. Submitted to Proceedings of Science for "The many
facets of extragalactic radio surveys: towards new scientific challenges",
Bologna, Italy 20-23 October 2015 (EXTRA-RADSUR2015
On multicurve models for the term structure
In the context of multi-curve modeling we consider a two-curve setup, with
one curve for discounting (OIS swap curve) and one for generating future cash
flows (LIBOR for a give tenor). Within this context we present an approach for
the clean-valuation pricing of FRAs and CAPs (linear and nonlinear derivatives)
with one of the main goals being also that of exhibiting an "adjustment factor"
when passing from the one-curve to the two-curve setting. The model itself
corresponds to short rate modeling where the short rate and a short rate spread
are driven by affine factors; this allows for correlation between short rate
and short rate spread as well as to exploit the convenient affine structure
methodology. We briefly comment also on the calibration of the model
parameters, including the correlation factor.Comment: 16 page
HFPK 334: An unusual Supernova Remnant in the Small Magellanic Cloud
We present new Australia Telescope Compact Array (ATCA) radio-continuum and
XMM-Newton/Chandra X-ray Observatory (CXO) observations of the unusual
supernova remnant HFPK 334 in the Small Magellanic Cloud (SMC). The remnant
follows a shell type morphology in the radio-continuum and has a size of
20~pc at the SMC distance. The X-ray morphology is similar, however, we
detect a prominent point source close to the center of the SNR exhibiting a
spectrum with a best fit powerlaw with a photon index of . This central point source is most likely a background object and cannot
be directly associated with the remnant. The high temperature, nonequilibrium
conditions in the diffuse region suggest that this gas has been recently
shocked and point toward a younger SNR with an age of years.
With an average radio spectral index of we find that an
equipartition magnetic field for the remnant is 90~G, a value
typical of younger SNRs in low-density environments. Also, we report detection
of scattered radio polarisation across the remnant at 20~cm, with a peak
fractional polarisation level of 255\%.Comment: 19 pages, 6-figures, submitted to A
Potentiometric Determination of the Stability Constants of 2-, 3- and 4-Hydroxybutyrato Complexes of Cobalt(II), Nickel(II), Cadmium(II) and Lead(II)
The stability constants of the title complexes were determined
potentiometrically using a quinhydrone electrode at (298.2 ± 0.1) K
in buffer solutions of ionic strength 2 mol dm-3 adjusted by addition
of NaC104• The numerical values of stability constants were evaluated
from experimental data by computer program based on a
weighted least squares method
XMMU J0541.8-6659, a new supernova remnant in the Large Magellanic Cloud
The high sensitivity of the XMM-Newton instrumentation offers the opportunity
to study faint and extended sources in the Milky Way and nearby galaxies such
as the Large Magellanic Cloud (LMC) in detail. The ROSAT PSPC survey of the LMC
has revealed more than 700 X-ray sources, among which there are 46 supernova
remnants (SNRs) and candidates. We have observed the field around one of the
most promising SNR candidates in the ROSAT PSPC catalogue, labelled [HP99] 456
with XMM-Newton, to determine its nature. We investigated the XMM-Newton data
along with new radio-continuum, near infrared and optical data. In particular,
spectral and morphological studies of the X-ray and radio data were performed.
The X-ray images obtained in different energy bands reveal two different
structures. Below 1.0 keV the X-ray emission shows the shell-like morphology of
an SNR with a diameter of ~73 pc, one of the largest known in the LMC. For its
thermal spectrum we estimate an electron temperature of (0.49 +/- 0.12)keV
assuming non-equilibrium ionisation. The X-ray images above 1.0 keV reveal a
less extended source within the SNR emission, located ~1' west of the centre of
the SNR and coincident with bright point sources detected in radio-continuum.
This hard component has an extent of 0.9' (i.e. ~13 pc at a distance of ~50
kpc) and a non-thermal spectrum. The hard source coincides in position with the
ROSAT source [HP99] 456 and shows an indication for substructure. We firmly
identify a new SNR in the LMC with a shell-like morphology and a thermal
spectrum. Assuming the SNR to be in the Sedov phase yields an age of ~23 kyr.
We explore possible associations of the hard non-thermal emitting component
with a pulsar wind nebula (PWN) or background active galactic nuclei (AGN).Comment: 8 pages, 7 figures, accepted for publication in Astronomy and
Astrophysic
Synthesis and characterization of poly (e-kaprolakton) / selenium nanoparticles biocomposite.
Ova doktorska disertacija predstavlja multidisciplinarno istraživanje u okviru kojeg su utvrđeni optimalni uslovi sinteze sfernih čestica poli (ε-kaprolaktona) (PCL-a) sa inkorporiranim, sintetisanim nanočesticama selena; izvršena je detaljna karakterizacija novodobijenog biokompozita različitim metodama fizičkohemijske analize; i ispitana su biološka svojstva značajna za njegovu potencijalnu primenu. Istraživanja su realizovana kroz tri faze...This doctoral dissertation represents a multidisciplinary study in which optimal synthesis conditions of poly-(ε-caprolactone) (PCL) spherical particles with incorporated selenium nanoparticles were determined, comprehensive characterization of obtained systems by various physicochemical methods was conducted and investigations of biological properties significant for the potential application of this biocomposite material were performed. In order to complete these tasks investigations were carried out into three consequent stages..
Polarographic Investigations of Some Metal Monocarboxylato Complexes . I. Monocarboxylato Complexes of Lead
By the polarographic method of DeFord and Hume the
stability constants of plumbous monocarboxylato co mplexes have
been determined, in water solutions of a constant ionic s trength 2
and a con stant concentration of 2 M of monocarboxylic acid. The
examinations were carried out in the monocarboxyla te concent r a t ion
range up to 2 M. The following values of stability const a nts were
obtained: formiato complexes /31= 13, /32 = 50, /33 = 30; acetato complexes /31 = 150 , /32 = 900, fJ3 = 3000; propionato complexes fJ 1 = 170, /J2 = 2200, /J3 = 5800 ; butyrato complexes /J 1 = 120 , /32 = 2000 , /3 3 = = 5800. It i s evident that with the increase of b ase strength and the size of the monoc arboxylate ion the complex stability increas es in the m\u27ljority of cases
Polarographic Investigations of Some Metal Monocarboxylato Complexes . I. Monocarboxylato Complexes of Lead
By the polarographic method of DeFord and Hume the
stability constants of plumbous monocarboxylato co mplexes have
been determined, in water solutions of a constant ionic s trength 2
and a con stant concentration of 2 M of monocarboxylic acid. The
examinations were carried out in the monocarboxyla te concent r a t ion
range up to 2 M. The following values of stability const a nts were
obtained: formiato complexes /31= 13, /32 = 50, /33 = 30; acetato complexes /31 = 150 , /32 = 900, fJ3 = 3000; propionato complexes fJ 1 = 170, /J2 = 2200, /J3 = 5800 ; butyrato complexes /J 1 = 120 , /32 = 2000 , /3 3 = = 5800. It i s evident that with the increase of b ase strength and the size of the monoc arboxylate ion the complex stability increas es in the m\u27ljority of cases
Two compact HII regions at the remote outskirts of the Magellanic Clouds
The H II regions LMC N191 and SMC N77 are among the outermost massive
star-forming regions in the Magellanic Clouds. So far, few works have dealt
with these objects despite their interesting characteristics. We aim at
studying various physical properties of these objects regarding their
morphology (in the optical and Spitzer IRAC wavelengths), ionized gas emission,
nebular chemical abundances, exciting sources, stellar content, age, presence
or absence of young stellar objects, etc. This study is based mainly on optical
ESO NTT observations, both imaging and spectroscopy, coupled with other archive
data, notably Spitzer images (IRAC 3.6, 4.5, 5.8, and 8.0 microns) and 2MASS
observations. We show the presence of two compact H II regions, a
low-excitation blob (LEB) named LMC N191A and a high-excitation blob (HEB)
named SMC N77A, and study their properties and those of their exciting massive
stars as far as spectral type and mass are concerned. We also analyze the
environmental stellar populations and determine their evolutionary stages.
Based on Spitzer IRAC data, we characterize the YSO candidates detected in the
direction of these regions. Massive star formation is going on in these young
regions with protostars of mass about 10 and 20 M_sun in the process of
formation.Comment: 14 pages, 8 figures, 6 tables; Accepted for publication in A&A. arXiv
admin note: substantial text overlap with arXiv:1102.125
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