An Innovative Direct NF-FF Transformation Technique with Helicoidal Scanning

A direct near-field-far-field transformation with helicoidal scanning is developed. It is based on the nonredundant sampling representation of electromagnetic fields and uses a spherical antenna modelling to determine the number of helix turns. Moreover, the number of voltage samples on each of them is fixed by the maximum transverse dimension of the antenna, both to simplify the mechanical scanning and to reduce the computational effort. This technique allows the evaluation of the antenna far field directly from a minimum set of near-field data without interpolating them. Although the number of near-field data employed by the developed technique is slightly increased with respect to that required by rigorously applying the nonredundant sampling representation on the helix, it is still remarkably smaller than that needed by the standard near-field-far-field transformation with cylindrical scanning. The effectiveness of the technique is assessed by numerical and experimental results

Near-Field/Far-Field Transformation with Helicoidal Scanning from Irregularly Spaced Data

A fast and accurate technique for the compensation of the probe positioning errors in the near-field/far-field transformation with helicoidal scanning is proposed in this paper. It relies on a nonredundant sampling representation using a spherical modelling of the antenna under test and employs an iterative scheme to evaluate the near-field data at the points fixed by the helicoidal nonredundant representation from the acquired irregularly distributed ones. Once these helicoidal data have been recovered, those required by a classical cylindrical near-field/far-field transformation are efficiently determined by using an optimal sampling interpolation algorithm. Some numerical tests assessing the effectiveness of the proposed approach and its stability with respect to random errors affecting the near-field data are shown

Two efficient procedures to correct the positioning errors in the plane-polar scanning

Two techniques to effectively compensate known positioning errors in a plane-polar near-field–far-field (NF–FF) transformation, using a minimum number of NF data and adopting an oblate ellipsoid to shape the considered antenna, are proposed and validated through experimental proofs. The former makes use of the singular value decomposition method to recover the voltage samples which would be acquired by the probe at the points fixed by the non-redundant sampling representation from the collected positioning error affected ones, whereas the latter employs an iterative scheme. The NF data required by the classical NF–FF transformation with plane-rectangular scanning are then efficiently evaluated via a two-dimensional optimal sampling interpolation formula. The effectiveness of the proposed techniques is assessed by experimental tests performed at the Antenna Characterisation Lab of the University of Salerno

Near-Field to Far-Field Transformation Techniques with Spiral Scannings: A Comprehensive Review

An overview of the near-field-far-field (NF-FF) transformation techniques with innovative spiral scannings, useful to derive the radiation patterns of the antennas commonly employed in the modern wireless communication systems, is provided in this paper. The theoretical background and the development of a unified theory of the spiral scannings for quasi-spherical and nonspherical antennas are described, and an optimal sampling interpolation expansion to evaluate the probe response on a quite arbitrary rotational surface from a nonredundant number of its samples, collected along a proper spiral wrapping it, is presented. This unified theory can be applied to spirals wrapping the conventional scanning surfaces and makes it possible to accurately reconstruct the NF data required by the NF-FF transformation employing the corresponding classical scanning. A remarkable reduction of the measurement time is so achieved, due to the use of continuous and synchronized movements of the positioning systems and to the reduced number of needed NF measurements. Some numerical and experimental results relevant to the spherical spiral scanning case when dealing with quasi-planar and electrically long antennas are shown

Far-Field Pattern Reconstruction from Near-Field Data Collected via a Nonconventional Plane-Rectangular Scanning: Experimental Testing

This paper deals with the experimental validation of an efficient near-field-far-field (NF-FF) transformation using the planar wide-mesh scanning (PWMS). Such a nonconventional plane-rectangular scanning technique is so named, since the sample grid is characterized by meshes wider and wider when going away from the center, and makes it possible to lower the number of needed measurements, as well as the time required for the data acquisition when dealing with quasi-planar antennas. It relies on the use of the nonredundant sampling representations of electromagnetic fields which employ an oblate ellipsoid or a surface formed by two circular "bowls" with the same aperture diameter but eventually different bending radii to shape a quasi-planar antenna. A two-dimensional optimal sampling interpolation formula allows the reconstruction of the NF data at any point on the measurement plane and, in particular, at those required by the classical NF-FF transformation with the conventional plane-rectangular scanning. The measurements, performed at the planar NF facility of the antenna characterization laboratories of Selex ES, have confirmed the effectiveness of this innovative scanning also from the experimental viewpoint

I prodotti "Beauty Care" nel canale farmaceutico

Indice: Il settore del beauty care - Il canale farmaceutico in Italia - Analisi della domanda - Fattori di successo e barriere all'entrata - Ciclo di vita del business - Raggruppamenti strategici e politiche di differenziazione e diversificazione - Strategie di marketing per il beauty care.. in farmacia - Swot analysis - Conclusion

Early raise of BDNF in hippocampus suggests induction of posttranscriptional mechanisms by antidepressants

<p>Abstract</p> <p>Background</p> <p>The neurotrophin BDNF has been implicated in the regulation of neuroplasticity, gene expression, and synaptic function in the adult brain, as well as in the pathophysiology of neuropsychiatric disorders and the mechanism of action of antidepressants. Antidepressant treatments have been shown to increase the expression of BDNF mRNA, although the changes measured were found to be different depending on various factors. A few studies only have measured levels of BDNF protein after antidepressant treatments, and poor correlation was found between mRNA and protein changes. We studied the time course of expression of BDNF mRNA and protein during drug treatments, in order to elucidate the temporal profile of regulation of this effector and whether mRNA and protein levels correlate. Rat groups were treated for 1, 2 or 3 weeks with fluoxetine or reboxetine; in additional groups drug treatment was followed by a washout week (3+1). Total BDNF mRNA was measured by Real Time PCR, pro- and mature BDNF proteins were measured by Western blot.</p> <p>Results</p> <p>We found that mature BDNF protein is induced more rapidly than mRNA, by both drugs in hippocampus (weeks 1–2) and by reboxetine in prefrontal/frontal cortex (week 1). The temporal profile of BDNF protein expression was largely inconsistent with that of mRNA, which followed the protein induction and reached a peak at week 3.</p> <p>Conclusion</p> <p>These results suggest that BDNF protein is rapidly elevated by antidepressant treatments by posttranscriptional mechanisms, and that induction of BDNF mRNA is a slower process.</p

Treatment-Resistant Schizophrenia: Genetic and Neuroimaging Correlates

Schizophrenia is a severe neuropsychiatric disorder that affects approximately 0.5–1% of the population. Response to antipsychotic therapy is highly variable, and it is not currently possible to predict those patients who will or will not respond to antipsychotic medication. Furthermore, a high percentage of patients, approximately 30%, are classified as treatment-resistant (treatment-resistant schizophrenia; TRS). TRS is defined as a non-response to at least two trials of antipsychotic medication of adequate dose and duration. These patients are usually treated with clozapine, the only evidence-based pharmacotherapy for TRS. However, clozapine is associated with severe adverse events. For these reasons, there is an increasing interest to identify better targets for drug development of new compounds and to establish better biomarkers for existing medications. The ability of antipsychotics to improve psychotic symptoms is dependent on their antagonist and reverse agonist activities at different neuroreceptors, and some genetic association studies of TRS have focused on different pharmacodynamic factors. Some genetic studies have shown an association between antipsychotic response or TRS and neurodevelopment candidate genes, antipsychotic mechanisms of action (such as dopaminergic, serotonergic, GABAergic, and glutamatergic) or pharmacokinetic factors (i.e., differences in the cytochrome families). Moreover, there is a growing body of literature on the structural and functional neuroimaging research into TRS. Neuroimaging studies can help to uncover the underlying neurobiological reasons for such resistance and identify resistant patients earlier. Studies examining the neuropharmacological mechanisms of antipsychotics, including clozapine, can help to improve our knowledge of their action on the central nervous system, with further implications for the discovery of biomarkers and the development of new treatments. The identification of the underlying mechanisms of TRS is a major challenge for developing personalized medicine in the psychiatric field for schizophrenia treatment. The main goal of precision medicine is to use genetic and brain-imaging information to improve the safety, effectiveness, and health outcomes of patients via more efficiently targeted risk stratification, prevention, and tailored medication and treatment management approaches. The aim of this review is to summarize the state of art of pharmacogenetic, pharmacogenomic and neuroimaging studies in TRS