103 research outputs found
Amoebic Abscess of the Liver
Selective angiography of the coeliac axis usually with superior mesenteric arteriography and hepatic isotopic scanning, have proved helpful in the diagnosis and differential diagnosis of amoebic liver abscess. In 16 patients who have had selective angiograms, arteriography showed tumours in 13, failed in 1 and was doubtful in 2. Isotopic scanning demonstrated tumours in 10, failed in 3 and was doubtful in 3. The results obtained with these 2 methods were confirmed by clinical, haematological, surgical, laparoscopic, postmortem, and therapeutic data. After treatment the selective arteriography was repeated in 12 patients and isotopic scanning in 9. Both methods showed agreement in demonstrating the disappearance of the abscess in all patients except one. In this one the isotopic scanning image persisted, whereas arteriography no longer showed the existence of a tumour. Arteriography and scintigraphy are complementary techniques for the diagnosis of tumours of the liver, the former being particularly useful for the aetiological diagnosis of the lesion
Collisional effects in the tokamap
AbstractPlasmas confined in tokamaks with non-symmetric perturbations are surrounded by a chaotic layer of magnetic field lines that guide charged particles to the tokamak wall. We use an analytical two-dimensional symplectic mapping to study the resulting fractal patterns of field line escape. However, particles may experience several collisions before escaping toward the tokamaks wall. We add a random collisional term to the field line mapping to investigate how the particle collisions modify their escape patterns
Anomalous synchronization threshold in coupled logistic maps
We consider regular lattices of coupled chaotic maps. Depending on lattice
size, there may exist a window in parameter space where complete
synchronization is eventually attained after a transient regime. Close outside
this window, an intermittent transition to synchronization occurs. While
asymptotic transversal Lyapunov exponents allow to determine the
synchronization threshold, the distribution of finite-time Lyapunov exponents,
in the vicinity of the critical frontier, is expected to provide relevant
information on phenomena such as intermittency. In this work we scrutinize the
distribution of finite-time exponents when the local dynamics is ruled by the
logistic map . We obtain a theoretical estimate for the
distribution of finite-time exponents, that is markedly non-Gaussian. The
existence of correlations, that spoil the central limit approximation, is shown
to modify the typical intermittent bursting behavior. The present scenario
could apply to a wider class of systems with different local dynamics and
coupling schemes.Comment: 6 pages, 6 figure
Validity of numerical trajectories in the synchronization transition of complex systems
We investigate the relationship between the loss of synchronization and the
onset of shadowing breakdown {\it via} unstable dimension variability in
complex systems. In the neighborhood of the critical transition to strongly
non-hyperbolic behavior, the system undergoes on-off intermittency with respect
to the synchronization state. There are potentially severe consequences of
these facts on the validity of the computer-generated trajectories obtained
from dynamical systems whose synchronization manifolds share the same
non-hyperbolic properties.Comment: 4 pages, 4 figure
Model for tumour growth with treatment by continuous and pulsed chemotherapy
Peer reviewedPreprin
Limits on the gravity wave contribution to microwave anisotropies
We present limits on the fraction of large angle microwave anisotropies which
could come from tensor perturbations. We use the COBE results as well as
smaller scale CMB observations, measurements of galaxy correlations, abundances
of galaxy clusters, and Lyman alpha absorption cloud statistics. Our aim is to
provide conservative limits on the tensor-to-scalar ratio for standard
inflationary models. For power-law inflation, for example, we find T/S<0.52 at
95% confidence, with a similar constraint for phi^p potentials. However, for
models with tensor amplitude unrelated to the scalar spectral index it is still
currently possible to have T/S>1.Comment: 23 pages, 7 figures, accepted for publication in Phys. Rev. D.
Calculations extended to blue spectral index, Fig. 6 added, discussion of
results expande
Lightweight Testing of Communication Networks with e-Motions
This paper illustrates the use of high-level domain specific
models to specify and test some performance properties of complex systems,
in particular Communication Networks, using a light-weight approach.
By following a Model-Driven Engineering (MDE) approach, we
show the benefits of constructing very abstract models of the systems
under test, which can then be easily prototyped and analysed to explore
their properties. For this purpose we use e-Motions, a language and its
supporting toolkit that allows end-user modelling of real-time systems
and their analysis in a graphical manner.Junta de Andalucía P07-TIC-03184Ministerio de Ciencia e Innovación TIN2008-0310
Bursting synchronization in networks with long-range coupling mediated by a diffusing chemical substance
Many networks of physical and biological interest are characterized by a
long-range coupling mediated by a chemical which diffuses through a medium in
which oscillators are embedded. We considered a one-dimensional model for this
effect for which the diffusion is fast enough so as to be implemented through a
coupling whose intensity decays exponentially with the lattice distance. In
particular, we analyzed the bursting synchronization of neurons described by
two timescales (spiking and bursting activity), and coupled through such a
long-range interaction network. One of the advantages of the model is that one
can pass from a local (Laplacian) type of coupling to a global (all-to-all) one
by varying a single parameter in the interaction term. We characterized
bursting synchronization using an order parameter which undergoes a transition
as the coupling parameters are changed through a critical value. We also
investigated the role of an external time-periodic signal on the bursting
synchronization properties of the network. We show potential applications in
the control of pathological rhythms in biological neural networks.Comment: 13 figure
Effect of acute treatment with a water-alcohol extract of Erythrina mulungu on anxiety-related responses in rats
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