15,176 research outputs found
Cerebral and Peripheral Tissue Oxygenation in Children Supported on ECMO for Cardio-Respiratory Failure
Extracorporeal membrane oxygenation (ECMO) is a rescue therapy for patients with cardio-respiratory failure. Establishing, maintaining and weaning from ECMO may increase the risk for intracranial injury. We used a dual channel near infrared system to monitor cerebral and peripheral tissue oxygenation in 3 venoarterial (VA) and 1 venovenous (VV) ECMO patients undergoing manipulations in the ECMO circuit flows. Spectral analysis was performed on the oxyhaemoglobin data collected from these patients with the aim of comparing oscillations at range of frequencies appearing in the two measurement sites
A new type of charged defect in amorphous chalcogenides
We report on density-functional-based tight-binding (DFTB) simulations of a
series of amorphous arsenic sulfide models. In addition to the charged
coordination defects previously proposed to exist in chalcogenide glasses, a
novel defect pair, [As4]--[S3]+, consisting of a four-fold coordinated arsenic
site in a seesaw configuration and a three-fold coordinated sulfur site in a
planar trigonal configuration, was found in several models. The
valence-alternation pairs S3+-S1- are converted into [As4]--[S3]+ pairs under
HOMO-to-LUMO electronic excitation. This structural transformation is
accompanied by a decrease in the size of the HOMO-LUMO band gap, which suggests
that such transformations could contribute to photo-darkening in these
materials.Comment: 5 pages, 2 figure
Bubbles and Filaments: Stirring a Cahn-Hilliard Fluid
The advective Cahn-Hilliard equation describes the competing processes of
stirring and separation in a two-phase fluid. Intuition suggests that bubbles
will form on a certain scale, and previous studies of Cahn-Hilliard dynamics
seem to suggest the presence of one dominant length scale. However, the
Cahn-Hilliard phase-separation mechanism contains a hyperdiffusion term and we
show that, by stirring the mixture at a sufficiently large amplitude, we excite
the diffusion and overwhelm the segregation to create a homogeneous liquid. At
intermediate amplitudes we see regions of bubbles coexisting with regions of
hyperdiffusive filaments. Thus, the problem possesses two dominant length
scales, associated with the bubbles and filaments. For simplicity, we use use a
chaotic flow that mimics turbulent stirring at large Prandtl number. We compare
our results with the case of variable mobility, in which growth of bubble size
is dominated by interfacial rather than bulk effects, and find qualitatively
similar results.Comment: 20 pages, 27 figures. RevTeX
Speckle interferometry at SOAR in 2015
The results of speckle interferometric observations at the SOAR telescope in
2015 are given, totalling 1303 measurements of 924 resolved binary and multiple
stars and non-resolutions of 260 targets. The separations range from 12 mas to
3.37" (median 0.17"); the maximum measured magnitude difference is 6.7 mag. We
resolved 27 pairs for the first time, including 10 as inner or outer subsystems
in previously known binaries, e.g. the 50-mas pair in Epsilon Cha. Newly
resolved pairs are commented upon. We discuss three apparently non-hierarchical
systems discovered in this series, arguing that their unusual configuration
results from projection. The resolved quadruple system HIP 71510 is studied as
well.Comment: 10 pages, 8 figures. Accepted for publication in AJ. The online
tables are not included, available from Tokovinin on request. arXiv admin
note: text overlap with arXiv:1506.0571
Classification of states of single- fermions with -pairing interaction
In this paper we show that a system of three fermions is exactly solvable for
the case of a single- in the presence of an angular momentum- pairing
interaction. On the basis of the solutions for this system, we obtain new sum
rules for six- symbols. It is also found that the "non-integer" eigenvalues
of three fermions with angular momentum around the maximum appear as
"non-integer" eigenvalues of four fermions when is around (or larger than)
and the Hamiltonian contains only an interaction between pairs of
fermions coupled to spin . This pattern is also found in
five and six fermion systems. A boson system with spin exhibits a similar
pattern.Comment: to be published in Physical Review
ADA to silicon transformations: the outline of a method
technical reportThis report explores the contention that a high-order language specification of a machine (such as an Ada program) can be methodically transformed into a hardware representation of that machine. One series of well-defined steps through which such transformations can take place is presented in this initial study
Twisted k-graph algebras associated to Bratteli diagrams
Given a system of coverings of k-graphs, we show that the cohomology of the
resulting (k+1)-graph is isomorphic to that of any one of the k-graphs in the
system. We then consider Bratteli diagrams of 2-graphs whose twisted
C*-algebras are matrix algebras over noncommutative tori. For such systems we
calculate the ordered K-theory and the gauge-invariant semifinite traces of the
resulting 3-graph C*-algebras. We deduce that every simple C*-algebra of this
form is Morita equivalent to the C*-algebra of a rank-2 Bratteli diagram in the
sense of Pask-Raeburn-R{\o}rdam-Sims.Comment: 28 pages, pictures prepared using tik
Influence of copper on the electronic properties of amorphous chalcogenides
We have studied the influence of alloying copper with amorphous arsenic
sulfide on the electronic properties of this material. In our
computer-generated models, copper is found in two-fold near-linear and
four-fold square-planar configurations, which apparently correspond to Cu(I)
and Cu(II) oxidation states. The number of overcoordinated atoms, both arsenic
and sulfur, grows with increasing concentration of copper. Overcoordinated
sulfur is found in trigonal planar configuration, and overcoordinated
(four-fold) arsenic is in tetrahedral configuration. Addition of copper
suppresses the localization of lone-pair electrons on chalcogen atoms, and
localized states at the top of the valence band are due to Cu 3d orbitals.
Evidently, these additional Cu states, which are positioned at the same
energies as the states due to ([As4]-)-([S_3]+) pairs, are responsible for
masking photodarkening in Cu chalcogenides
Surface Partition of Large Fragments
The surface partition of large fragments is derived analytically within a
simple statistical model by the Laplace-Fourier transformation method. In the
limit of small amplitude deformations, a suggested Hills and Dales Model
reproduces the leading term of the famous Fisher result for the surface entropy
with an accuracy of a few percent. The surface partition of finite fragments is
discussed as well.Comment: 4 pages, 1 figur
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