Síndrome meníngeo y síndrome de cola de caballo tras cirugía de hernia discal lumbar L5-S1: evolución a los dos años / No disponible

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Spectral analysis of the weighted Laplacian in slip and no-slip flows.

Slip boundary conditions for the velocity field impact on the spectral properties of the advection-diffusion operator describing transport of passive particles in laminar parallel flows. By considering the Hermitian operator (referred to as the weighted Laplacian), describing the interplay between axial convection and cross-sectional diffusion of a scalar field, we show that the spectral watershed between slip and no-slip boundary conditions is a qualitatively different scaling behavior of the mean of the normalized eigenfunctions of the weighted Laplacian. The occurrence of slip conditions also influences the scaling of the density of states as regards both the leading and the subleading term in the Weyl's expansion.

Slow manifold structure in explosive kinetics. 1. Bifurcations of points-at-infinity in prototypical models.

This article analyzes in detail the global geometric properties (structure of the slow and fast manifolds) of prototypical models of explosive kinetics (the Semenov model for thermal explosion and the chain-branching model). The concepts of global or generalized slow manifolds and the notions of heterogeneity and alpha-omega inversion for invariant manifolds are introduced in order to classify the different geometric features exhibited by two-dimensional kinetic schemes by varying model parameters and to explain the phenomena that may occur in model reduction practice. This classification stems from the definition of suitable Lyapunov-type numbers and from the analysis of normal-to-tangent stretching rates. In the case of the Semenov model, we show that the existence of a global slow manifold and its properties are controlled by a transcritical bifurcation of the points-at-infinity, which can be readily identified by analyzing the Poincaré projected system. The issue of slow manifold uniqueness and the implications of the theory with regard to the practical definition of explosion limits are thoroughly addressed.

Slow manifold structure in explosive kinetics. 2. Extension to higher dimensional systems.

This Article extends the geometric analysis of slow invariant manifolds in explosive kinetics developed by Creta et al. to three-dimensional and higher systems. Invariant manifolds can be characterized by different families of Lyapunov-type numbers, based either on the relative growth of normal to tangential perturbations or on the deformation of m-dimensional volume elements (if the manifold is m-dimensional) and of the complementary (n - m)-elements in the normal orthogonal complement. The latter approach, based on elementary concepts of exterior algebra, is particularly simple because the evolution of the relevant volume elements can be related to suitable local stretching rates, and local analysis can be performed directly from the knowledge of the Jacobian matrix of the vector field. Several examples of bifurcations of the points-at-infinity, which modify the manifold structure, are discussed for 3-D models of exothermic reactions.

[Nonalcoholic steatohepatitis associated with ovarian stromal hyperplasia]. / Esteatohepatitis no alcohólica asociada a hiperplasia estromal ovárica.

Alterations in liver function tests have previously been reported in patients with ovarian disease. We report the case of a woman with prolonged hypertransaminasemia, significant hirsutism and android phenotype who was diagnosed with nonalcoholic steatohepatitis and ovarian stromal hyperplasia.

Esteatohepatitis no alcohólica asociada a hiperplasia estromal ovárica / Nonalcoholic steatohepatitis associated with ovarian stromal hyperplasia

Se han documentado alteraciones en las pruebas de función hepática en pacientes con enfermedad ovárica. El caso que presentamos es el de una paciente con hipertransaminasemia prolongada, hirsutismo importante y fenotipo androide, que es diagnosticada de esteatohepatitis no alcohólica e hiperplasia estromal ovárica

Alterations in liver function tests have previously been reported in patients with ovarian disease. We report the case of a woman with prolonged hypertransaminasemia, significant hirsutism and android phenotype who was diagnosed with nonalcoholic steatohepatitis and ovarian stromal hyperplasia

Advection diffusion in nonchaotic closed flows: non-Hermitian operators, universality, and localization.

The qualitative spectral properties characterizing the advection-diffusion operator in two-dimensional steady incompressible flows can be obtained from the analysis of simple model flows on the torus, the velocity field of which attains the simple expression v (x) = (0, v(y) (x) ) . For this class of simple flows, the advection-diffusion operator reduces to a one-dimensional Schrödinger operator in the presence of an imaginary potential, which shares some spectral analogies with non-Hermitian quantum operators (e.g., spectral invariance), and is characterized by eigenfunction localization. The latter property (i.e., eigenfunction localization) is strictly related to the occurrence of a universal scaling of the eigenvalue spectrum with the Peclet number, the scaling exponent of which depends exclusively on the local behavior of the potential close to its critical points. The analysis is extended to a class of unbounded non-Hermitian operators, which include the Laplacian and the biharmonic operators coupled to an imaginary potential as special cases.

Spectral properties and transport mechanisms of partially chaotic bounded flows in the presence of diffusion.

The spectral properties of the Poincaré operator associated with the advection-diffusion equation for partially chaotic periodic flows defined in bounded domains are analyzed in this Letter. For vanishingly small diffusivities (i.e., for the Peclet number tending to infinity) the dominant eigenvalue Lambda exhibits the scaling Lambda approximately Pe-alpha, where the exponent alpha in (0,1) depends on the global property of the flow (shape, geometry, and symmetry of quasiperiodic islands). The value of the exponent alpha is an indicator of qualitatively different transport mechanisms and depends on the localization properties of the corresponding eigenfunctions.

Geometry of reaction interfaces in chaotic flows.

The analysis of transport-controlled reactions in chaotic flows provides a physical frame to extend the concept of the intermaterial contact area (ICA)--introduced in the purely kinematic case--to mixing systems with diffusion, where the ICA is identified through the reaction interface between segregated reactants. We show that the dynamics of the ICA undergoes a crossover from kinematics-dominated exponential growth to a persistent oscillatory regime resulting from the intertwined action of advection and diffusion. The scaling of the crossover length versus the Peclet number is analyzed.

[Multivariate analysis of the risk of hemorrhagic recurrence in gastroduodenal ulcer. Study of a prospective series]. / Análisis multivariante del riesgo de recidiva hemorrágica en la úlcera gastroduodenal. Estudio de una serie prospectiva.

AIM: To construct a model to enable calculation of rebleeding risk in patients admitted to a hospital emergency department with upper gastrointestinal bleeding secondary to a gastric or duodenal ulcer. METHODS: We analyzed 317 patients admitted during a 13-month period with an episode of upper gastrointestinal bleeding secondary to a gastroduodenal ulcer. The patients were followed-up for 30 days after discharge. Uni- and multivariate analysis of the clinical and endoscopic variables was performed on variables that could be associated with an increased risk of rebleeding. RESULTS: In the univariate analysis the following variables were significantly associated with an increased risk of rebleeding: the presence of blood in the endoscopically examined tract (p < 0.0001), clean ulcer base (p < 0.0001), low blood flow (p < 0.047) and size of the ulcer > 2 cm (p < 0.004). Independent risk variables identified by multivariate logistic regression analysis were low cardiac output, the presence of blood in the endoscopically examined tract, size of the ulcer, and type of ulcer base. CONCLUSION: Patients with a clean ulcer base, smaller than 2 cm, without blood in the endoscopically examined tract and with stable hemodynamics were at very low risk of rebleeding and could be discharged directly from the emergency room.

Measure-theoretical properties of the unstable foliation of two-dimensional differentiable area-preserving systems.

This article analyzes in detail the statistical and measure-theoretical properties of the nonuniform stationary measure, referred to as the w-invariant measure, associated with the spatial length distribution of the integral manifolds of the unstable invariant foliation in two-dimensional differentiable area-preserving systems. The analysis is developed starting from a sequence of analytical approximations for the associated density. These approximations are related to the properties of the Jacobian matrix of the nth iteration of a Poincaré map. The w-invariant measure plays a fundamental role in the study of transport phenomena in laminar-chaotic fluid-mixing systems, for which it furnishes the asymptotic invariant distribution of intermaterial contact length between two fluids. The w-invariant measure turns out to be singular and exhibits multifractal features. Its associated density displays local self-similarity in an epsilon neighborhood of hyperbolic periodic points. The cancellation exponent of the signed measure associated with the w measure by attaching at each point the direction of the field of the asymptotic unstable eigenvectors is also analyzed. The only case for which the w-invariant measure is absolutely continuous is given by the conjugation of hyperbolic toral automorphisms with a linear automorphism. The connections with the statistical properties, and in particular with the stretching dynamics, are addressed in detail.

[A case of non Hodgkin Lymphoma in a patient with hepatic cirrhosis by the hepatitis C virus]. / Un caso de linfoma no hodgkiniano en una paciente con cirrosis hepática por el virus de la hepatitis C.

We present a case of non-Hodgkin's lymphoma of B cells in a patient with cirrhosis by hepatitis C virus. Our patient presented scarce symptomatology related with non-Hodgkin's lymphoma. A notable hyperbilirrubinaemia with hypoalbuminaemia were the only features that allowed us to suspect the diagnosis. The diagnostic was proved by necroscopic study. There are several factors involved in the etiology of non-Hodgkin's lymphoma, including infectious agents. Recent Italian studies have suggested an association between C virus infection and non-Hodgkin's lymphoma. We have carried out a bibliographical revision of this association to conclude that important geographical differencies must be pointed out.

[Gastrointestinal hemorrhage secondary to a pancreatic pseudoaneurysm]. / Hemorragia digestiva secundaria a un seudoaneurisma pancreático.

Acute hemorrhage from pancreatic pseudoaneurysm is the most rapidly fatal complication of pancreatitis, with a reported mortality rate of > 90% in untreated patients. The diagnosis of pancreatic pseudoaneurysm requires a high index of suspicion and the abdominal angiography is the gold standard. Transcatheter embolization is an alternative to surgery for treatment in selected patients. Early diagnosis and treatment decrease the mortality dramatically. We describe a patient with a gastrointestinal bleeding from a ruptured pancreatic pseudoaneurysm, with an angiography diagnosis and transcatheter embolization. We treated the pseudocyst with an endoscopic drainage. A review of literature is presented.

[Chronic calcifying pancreatitis and extracorporeal pancreatic lithotripsy]. / Pancreatitis crónica calcificante y litotripsia pancreática extracorpórea.

Abdominal pain is the most frequent symptom of chronic pancreatitis and may, on occasions, lead to great treatment problems. The case of a 35-years-old patient diagnosed with chronic calcifying pancreatitis of enolic etiology who showed dilatation of the main pancreatic duct and intracanalicular lithiasis is reported. Medical, endoscopic and surgical alternatives failed but fragmentation of the lithiasis by extracorporeal lithotripsy was successful.

[Validity of death certificates for cancer in Mallorca]. / Validez de los certificados de defunción por cáncer en Mallorca.

We assessed the quality and completeness of the information of death certificates (CMD) for cancer in Mallorca during 1989. Likewise we studied the possible bias introduced by the excluded cases for lack of clinical information (DCO cases). We compared the information of the death certificates with the clinical records and data of the Population-based Cancer Registry. A global concordance of 77.2% was obtained out of 1,173 certificates. This concordance varied according to sex (males: 79.8%, women: 73.1%; p < 0.01), place of death (hospital: 83.1%, home: 69.6%; p < 0.001) and age ( < 50 years: 77.8%; > 70 years: 74.2%; p < 0.05). The best notified sites were: breast, lung, and leukemias and the worst, unknown and poorly defined sites, bones and soft tissue tumours. We detected that the death certificates carry a subnotification of at least 5% in cancer deaths. Even so, they result a valid source of information for the Population-based Cancer Registry. The cases excluded for lack of clinical documentation present a more advanced age and a greater proportion of hepatic cancers and unknown and poorly defined sites.