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 $x \mapsto 4x(1-x)$. 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