Cálculo de impedancia característica de líneas de cinta usando compresión espacial, diferencias finitas y algoritmos genéticos

In this paper we computed the characteristic impedance of homogeneous Striplines with finite or infinite dielectric substrate, using the Finite Differences Method (FDM) and Spatial Compression (CE), with transformation functions found through Genetics Algorithms (GAs). The CE consist on the transformation of any plane transmission line domain with very different dimensions, in a rectangle in which the images of the dimensions maintain proportions that make easier the FDM application in an efficient way, without supposing that the dielectric substrate is infinite. The coefficients of the transformation were found using GAs. We obtained Characteristic Impedance values for lines with different relations of dimensions and for finite or infinite dielectric substrates. The results were compared with results found in the literature, obtaining good agreement

Anisotropic multiple scattering in diffuse media

The multiple scattering of scalar waves in diffusive media is investigated by means of the radiative transfer equation. This approach amounts to a resummation of the ladder diagrams of the Born series; it does not rely on the diffusion approximation. Quantitative predictions are obtained, concerning various observables pertaining to optically thick slabs, such as the mean angle-resolved reflected and transmitted intensities, and the shape of the enhanced backscattering cone. Special emphasis is put on the dependence of these quantities on the anisotropy of the cross-section of the individual scatterers, and on the internal reflections due to the optical index mismatch at the boundaries of the sample. The regime of very anisotropic scattering, where the transport mean free path $\ell^*$ is much larger than the scattering mean free path $\ell$, is studied in full detail. For the first time the relevant Schwarzschild-Milne equation is solved exactly in the absence of internal reflections, and asymptotically in the regime of a large index mismatch. An unexpected outcome concerns the angular width of the enhanced backscattering cone, which is predicted to scale as $\Delta\theta\sim\lambda/\sqrt{\ell\ell^*}$, in contrast with the generally accepted $\lambda/\ell^*$ law, derived within the diffusion approximation.Comment: 53 pages TEX, including 2 tables. The 4 figures are sent at reques

Tic disorders: from pathophysiology to treatment

Tic disorders are stereotypic behaviours,more frequent than once believed, and therefore likely to be encountered by primary care physicians. Tics usually begin in childhood and are the clinical hallmark of Tourette Syndrome (TS), the most common cause of tics. TS is a relatively common neurobehavioural disorder with a spectrum of manifestations that wax and wane during its natural course. The pathophysiology of tics, at molecular and cellular level, is still unknown,whereas structural and functional neuroimaging studies have shown the involvement of the basal ganglia and related cortico-striato-thalamo-cortical circuits, and the dopaminergic neuronal system. Moreover, TS has a strong genetic background. The management of TS is often complicated by the presence of attention-deficit/hyperactivity disorder, obsessivecompulsive disorder, and other behaviour disorders. The correct diagnosis is a fundamental step for a proper management of these disorders, and a multimodal treatment is usually indicated. This approach includes educational and supportive interventions, as well as pharmacological treatments when tics are at their worst

Tic disorders: from pathophysiology to treatment

Tic disorders are stereotypic behaviours,more frequent than once believed, and therefore likely to be encountered by primary care physicians. Tics usually begin in childhood and are the clinical hallmark of Tourette Syndrome (TS), the most common cause of tics. TS is a relatively common neurobehavioural disorder with a spectrum of manifestations that wax and wane during its natural course. The pathophysiology of tics, at molecular and cellular level, is still unknown,whereas structural and functional neuroimaging studies have shown the involvement of the basal ganglia and related cortico-striato-thalamo-cortical circuits, and the dopaminergic neuronal system. Moreover, TS has a strong genetic background. The management of TS is often complicated by the presence of attention-deficit/hyperactivity disorder, obsessivecompulsive disorder, and other behaviour disorders. The correct diagnosis is a fundamental step for a proper management of these disorders, and a multimodal treatment is usually indicated. This approach includes educational and supportive interventions, as well as pharmacological treatments when tics are at their worst

Lithium therapy effects on the reproductive system

The chemical properties of lithium (Li) make it an extremely active substance in the body. It is active in the form of Li+ ion, so all salts have the same pharmacological action. Li salts are used to treat manic-depressive disorders (bipolar affective disorders), depressive manic symptoms that include hurried speech, hyperactivity, little need for sleep, aggression, and cholera. Li is a mood stabilizer and reduces extreme behaviors by restoring the balance of neurotransmitters in the brain. The modifications of the cAMP signaling pathway, alterations in the phosphoinositol pathway, variations in the availability of GABA and glutamate are some described mechanisms of action of Li to achieve its antimanic and mood stabilizing effects. Thus, lithium exerts modifications on the circadian rhythm, neurotransmission processes in the central nervous system, and neuroendocrine functions.Li therapies have benefits that have not yet been overtaken by other drugs. However, there is also some resistance to using these drugs, partly due to the lack of knowledge of the real impact of its adverse effects although some of them are reversible with the discontinuation of treatment. However, less known and more controversial are the toxic effects of lithium therapy on the reproductive system and, therefore, on human sexual functions. Studies in human and laboratory animals on the effects of Li have demonstrated significant effects on the functioning of the hypothalamic-pituitary gonadal axis. Therefore, this ion may alter human reproduction.Fil: Filippa, Veronica Palmira. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis; Argentina. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Departamento de Bioquímica y Ciencias Biológicas; ArgentinaFil: Mohamed, Fabian Heber. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Departamento de Bioquímica y Ciencias Biológicas; Argentin