10,420 research outputs found
Unusual echocardiographic finding leading to diagnosis of pulmonary sequestration
Pulmonary sequestration is an embryonic mass of non- functioning lung tissue that
does not communicate with the tracheobronchial tree and has a reported incidence of
0.15%-6.4% of all the pulmonary malformations. This anomaly is classified as either
intralobar or extralobar with the later variety lying outside the normal investment of
visceral pleura. The arterial supply is predominantly by an anomalous artery usually
arising from either abdominal or thoracic aorta, while the venous drainage occurs
commonly via systemic rather than pulmonary veins. Identification of the anomalous arterial supply has therapeutic implication because the majority of infants clinically present large shunt lesions attributed to these
channels in early infancy.
The diagnosis in such cases is usually established by computed tomography (CT), angiography, magnetic resonance angiography and conventional angiography. This article reports a 28 day old neonate who presented with features of large shunt lesion, in which echocardiography was instrumental in the diagnosis of a large collateral supplying the sequestrated lung.peer-reviewe
Implementation of higher-order absorbing boundary conditions for the Einstein equations
We present an implementation of absorbing boundary conditions for the
Einstein equations based on the recent work of Buchman and Sarbach. In this
paper, we assume that spacetime may be linearized about Minkowski space close
to the outer boundary, which is taken to be a coordinate sphere. We reformulate
the boundary conditions as conditions on the gauge-invariant
Regge-Wheeler-Zerilli scalars. Higher-order radial derivatives are eliminated
by rewriting the boundary conditions as a system of ODEs for a set of auxiliary
variables intrinsic to the boundary. From these we construct boundary data for
a set of well-posed constraint-preserving boundary conditions for the Einstein
equations in a first-order generalized harmonic formulation. This construction
has direct applications to outer boundary conditions in simulations of isolated
systems (e.g., binary black holes) as well as to the problem of
Cauchy-perturbative matching. As a test problem for our numerical
implementation, we consider linearized multipolar gravitational waves in TT
gauge, with angular momentum numbers l=2 (Teukolsky waves), 3 and 4. We
demonstrate that the perfectly absorbing boundary condition B_L of order L=l
yields no spurious reflections to linear order in perturbation theory. This is
in contrast to the lower-order absorbing boundary conditions B_L with L<l,
which include the widely used freezing-Psi_0 boundary condition that imposes
the vanishing of the Newman-Penrose scalar Psi_0.Comment: 25 pages, 9 figures. Minor clarifications. Final version to appear in
Class. Quantum Grav
New Approximability Results for the Robust k-Median Problem
We consider a robust variant of the classical -median problem, introduced
by Anthony et al. \cite{AnthonyGGN10}. In the \emph{Robust -Median problem},
we are given an -vertex metric space and client sets . The objective is to open a set of
facilities such that the worst case connection cost over all client sets is
minimized; in other words, minimize . Anthony
et al.\ showed an approximation algorithm for any metric and
APX-hardness even in the case of uniform metric. In this paper, we show that
their algorithm is nearly tight by providing
approximation hardness, unless . This hardness result holds even for uniform and line
metrics. To our knowledge, this is one of the rare cases in which a problem on
a line metric is hard to approximate to within logarithmic factor. We
complement the hardness result by an experimental evaluation of different
heuristics that shows that very simple heuristics achieve good approximations
for realistic classes of instances.Comment: 19 page
Mesomorphic properties of alkoxybenzylidene- aminoacetophenones
Liquid crystal phase transitions in compounds of alkoxybenzylidene-aminoacetophene serie
The Ironies of Human Mind: A Case of Rett Syndrome
Background: Rett Syndrome (RS) is a chromosome X-linked genetic neurological disorder characterized by developmental regression, particularly in relation to expressive language and use of the hands. It is also associated with profound mental retardation and almost exclusively affects females.Case Details: A four and a half year old girl reported to our dental OPD for a dental checkup. On complete examination, she was diagnosed to be suffering from Rett Syndrome. Preventive therapies and proper oral hygiene instructions were explained to her mother.Conclusion: Early diagnosis of such disorders is extremely important along with treatment of patients’ problems with love and care to prevent them from further pain and stress.Keyowrds: Rett Syndrome, stereotypic hand movements, behavior therapy
Free Convection Flow with Constant Heat Sources in a Porous Channel
The effect of constant heat sources on fully developed free convection flow of a viscous fluid in a porous channel oriented in the direction of the body force has been studied when the walls are maintained at constant temperatures. It has been found that both the velocity and temperature depend on the heat source parameter alpha and the dimensional group Q representing the free convection effects
On the NP-Hardness of Approximating Ordering Constraint Satisfaction Problems
We show improved NP-hardness of approximating Ordering Constraint
Satisfaction Problems (OCSPs). For the two most well-studied OCSPs, Maximum
Acyclic Subgraph and Maximum Betweenness, we prove inapproximability of
and .
An OCSP is said to be approximation resistant if it is hard to approximate
better than taking a uniformly random ordering. We prove that the Maximum
Non-Betweenness Problem is approximation resistant and that there are width-
approximation-resistant OCSPs accepting only a fraction of
assignments. These results provide the first examples of
approximation-resistant OCSPs subject only to P \NP
Blackbody radiation shift in a 43Ca+ ion optical frequency standard
Motivated by the prospect of an optical frequency standard based on 43Ca+, we
calculate the blackbody radiation (BBR) shift of the 4s_1/2-3d_5/2 clock
transition, which is a major component of the uncertainty budget. The
calculations are based on the relativistic all-order single-double method where
all single and double excitations of the Dirac-Fock wave function are included
to all orders of perturbation theory. Additional calculations are conducted for
the dominant contributions in order to evaluate some omitted high-order
corrections and estimate the uncertainties of the final results. The BBR shift
obtained for this transition is 0.38(1) Hz. The tensor polarizability of the
3d_5/2 level is also calculated and its uncertainty is evaluated as well. Our
results are compared with other calculations.Comment: 4 page
- …