4,514 research outputs found
Arterial pathology in canine mucopolysaccharidosis-I and response to therapy.
Mucopolysaccharidosis-I (MPS-I) is an inherited deficiency of α-L-iduronidase (IdU) that causes lysosomal accumulation of glycosaminoglycans (GAG) in a variety of parenchymal cell types and connective tissues. The fundamental link between genetic mutation and tissue GAG accumulation is clear, but relatively little attention has been given to the morphology or pathogenesis of associated lesions, particularly those affecting the vascular system. The terminal parietal branches of the abdominal aorta were examined from a colony of dogs homozygous (MPS-I affected) or heterozygous (unaffected carrier) for an IdU mutation that eliminated all enzyme activity, and in affected animals treated with human recombinant IdU. High-resolution computed tomography showed that vascular wall thickenings occurred in affected animals near branch points, and associated with low endothelial shear stress. Histologically these asymmetric 'plaques' entailed extensive intimal thickening with disruption of the internal elastic lamina, occluding more than 50% of the vascular lumen in some cases. Immunohistochemistry was used to show that areas of sclerosis contained foamy (GAG laden) macrophages, fibroblasts and smooth muscle cells, with loss of overlying endothelial basement membrane and claudin-5 expression. Lesions contained scattered cells expressing nuclear factor-κβ (p65), increased fibronectin and transforming growth factor β-1 signaling (with nuclear Smad3 accumulation) in comparison to unaffected vessels. Intimal lesion development and morphology was improved by intravenous recombinant enzyme treatment, particularly with immune tolerance to this exogenous protein. The progressive sclerotic vasculopathy of MPS-I shares some morphological and molecular similarities to atherosclerosis, including formation in areas of low shear stress near branch points, and can be reduced or inhibited by intravenous administration of recombinant IdU
Efficiency of the Incomplete Enumeration algorithm for Monte-Carlo simulation of linear and branched polymers
We study the efficiency of the incomplete enumeration algorithm for linear
and branched polymers. There is a qualitative difference in the efficiency in
these two cases. The average time to generate an independent sample of
sites for large varies as for linear polymers, but as for branched (undirected and directed) polymers, where
. On the binary tree, our numerical studies for of order
gives . We argue that exactly in this
case.Comment: replaced with published versio
The contribution of the Unresolved Extragalactic Radio Sources to the Brightness Temperature of the sky
The contribution of the Unresolved Extragalactic Radio Sources to the diffuse
brightness of the sky was evaluated using the source number - flux measurements
available in literature. We first optimized the fitting function of the data
based on number counts distribution. We then computed the brightness
temperature at various frequencies from 151 MHz to 8440 MHz and derived its
spectral dependence. As expected the frequency dependence can be described by a
power law with a spectral index , in agreement with the
flux emitted by the {\it steep spectrum} sources. The contribution of {\it flat
spectrum} sources becomes relevant at frequencies above several GHz. Using the
data available in literature we improved our knowledge of the brightness of the
unresolved extragalactic radio sources. The results obtained have general
validity and they can be used to disentangle the various contributions of the
sky brightness and to evaluate the CMB temperature.Comment: Accepted for publication in the Astrophysical Journa
Ongoing Star Formation in the BL Lacertae object PKS 2005-489
We present VLT long slit optical spectroscopy of the luminous BL Lacertae
object PKS 2005-489. The high signal-to-noise ratio and the good spatial
resolution of the data allow us to detect the signatures of ongoing star
formation in an extended rotating ring, at ~4 kpc from the nucleus. We find
that the ring is almost perpendicular to the radio axis and its total star
formation rate is ~1 MSol/yr. We briefly discuss the concomitant presence of
recent star formation and nuclear activity.Comment: Accepted for publication by ApJ
Franck-Condon Factors and Radiative Lifetime of the A^{2}\Pi_{1/2} - X^{2}\Sigma^{+} Transition of Ytterbium Monoflouride, YbF
The fluorescence spectrum resulting from laser excitation of the
A^{2}\Pi_{1/2} - X^{2}\Sigma^{+} (0,0) band of ytterbium monofluoride, YbF, has
been recorded and analyzed to determine the Franck-Condon factors. The measured
values are compared with those predicted from Rydberg-Klein-Rees (RKR)
potential energy curves. From the fluorescence decay curve the radiative
lifetime of the A^{2}\Pi_{1/2} state is measured to be 28\pm2 ns, and the
corresponding transition dipole moment is 4.39\pm0.16 D. The implications for
laser cooling YbF are discussed.Comment: 5 pages, 5 figure
Continued fraction solution of Krein's inverse problem
The spectral data of a vibrating string are encoded in its so-called
characteristic function. We consider the problem of recovering the distribution
of mass along the string from its characteristic function. It is well-known
that Stieltjes' continued fraction provides a solution of this inverse problem
in the particular case where the distribution of mass is purely discrete. We
show how to adapt Stieltjes' method to solve the inverse problem for a related
class of strings. An application to the excursion theory of diffusion processes
is presented.Comment: 18 pages, 2 figure
Semiclassical time--dependent propagation in three dimensions: How accurate is it for a Coulomb potential?
A unified semiclassical time propagator is used to calculate the
semiclassical time-correlation function in three cartesian dimensions for a
particle moving in an attractive Coulomb potential. It is demonstrated that
under these conditions the singularity of the potential does not cause any
difficulties and the Coulomb interaction can be treated as any other
non-singular potential. Moreover, by virtue of our three-dimensional
calculation, we can explain the discrepancies between previous semiclassical
and quantum results obtained for the one-dimensional radial Coulomb problem.Comment: 8 pages, 4 figures (EPS
The Evolution of Radio Galaxies at Intermediate Redshift
We describe a new estimate of the radio galaxy 1.4 GHz luminosity function
and its evolution at intermediate redshifts (z~0.4). Photometric redshifts and
color selection have been used to select Bj<23.5 early-type galaxies from the
Panoramic Deep Fields, a multicolor survey of two 25 sq deg fields.
Approximately 230 radio galaxies have then been selected by matching early-type
galaxies with NVSS radio sources brighter than 5 mJy. Estimates of the 1.4 GHz
luminosity function of radio galaxies measure significant evolution over the
observed redshift range. For an Omega_M=1 cosmology the evolution of the radio
power is consistent with luminosity evolution where P(z)=P(0)(1+z)^{k_L} and
3<k_L<5. The observed evolution is similar to that observed for UVX and X-ray
selected AGN and is consistent with the same physical process being responsible
for the optical and radio luminosity evolution of AGN.Comment: 26 pages, 9 Figures, Accepted for Publication in A
Implementation of quantum gates and preparation of entangled states in cavity QED with cold trapped ions
We propose a scheme to perform basic gates of quantum computing and prepare
entangled states in a system with cold trapped ions located in a single mode
optical cavity. General quantum computing can be made with both motional state
of the trapped ion and cavity state being qubits. We can also generate
different kinds of entangled states in such a system without state reduction,
and can transfer quantum states from the ion in one trap to the ion in another
trap. Experimental requirement for achieving our scheme is discussed.Comment: To appear in J. Opt.
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