Incremento della direttività di un array di antenne attraverso estrapolazione del campo con applicazione ad un poligono acustico

La tesi presenta un algoritmo applicabile ad array lineari uniformi con spaziatura minore di λ/2 (spaziatura critica), con lo scopo di ottenere un incremento della loro direttività. Per poter ottenere tale scopo, l'algoritmo effettua l’estrapolazione del campo effettivamente misurato dagli M sensori presenti all'interno dell’array, in modo da prolungare virtualmente l’array stesso. Viene generato in questo modo un array, in parte reale e in parte virtuale, di N elementi, con N>M, formato dagli M elementi fisicamente presenti nell'array originale, e da N-M elementi virtuali, ognuno distanziato dal successivo della stessa quantità espressa in frazioni della lunghezza d'onda, ma comunque minori della spaziatura critica. L'algoritmo è applicabile in ambito elettromagnetico e acustico, ma il lavoro di questa tesi si è concentrato su quest'ultimo, in particolare con riferimento al nuovo poligono acustico subacqueo del Centro di Supporto e Sperimentazione Navale di La Spezia. L'incremento di direttività viene evidenziato a mezzo di risultati ottenuti sia per simulazione, sia su misurazioni ottenute dal poligono nel corso di una campagna sperimentale a mare

Design and synthesis of novel Acadesine analogues as Adenosine Monophosphate-activated Protein Kinase (AMPK) activators

AMPK (5' AMP-activated protein kinase or 5' adenosine monophosphate-activated protein kinase) is an enzyme that plays a key role in cellular energy homeostasis. It consists of three subunits that together make a functional enzyme. It is expressed in a number of tissues, including liver, brain, and skeletal muscle. The ultimate effect of AMPK activation is the stimulation of hepatic fatty acid oxidation and ketogenesis, inhibition of cholesterol synthesis, lipogenesis, triglyceride synthesis, inhibition of adipocyte lipolysis and lipogenesis, stimulation of skeletal muscle fatty acid oxidation, muscle glucose uptake and modulation of insulin secretion by pancreatic beta-cells. Mammalian AMPK is activated by binding to AMP, but this activation is inhibited by ATP with a ratio 1:3. Because cellular ADP/ATP ratios remain nearly constant due to the equilibrium maintained by adenylate kinase, it is thought that AMPK activity in vivo depends primarily on the ATP/AMP ratio, the primary determinant of cellular energy charge. Lowered cellular energy charge can arise either from inhibition of ATP synthesis, for example, in hypoxia, or by increased ATP consumption, as happens in skeletal muscle during exercise. When energy charge is low, active AMPK inhibits numerous ATP consuming pathways and also activates mobilization of intracellular energy stores to produce ATP. On the contrary, when energy charge is high, AMPK inactivation is favored, leading to enhancement of energy storage and use. AMPK also functions in organism-level energy homeostasis by responding to systemically circulating hormones, including leptin, adiponectin, and resistin. The development of novel AMPK activators started from an accurate study of acadesine chemical structure (AICAR or 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside), the most important AMPK-activator known in literature, that showed positive results in the treatment of type 2 diabetes, obesity, ischemic injury and inflammation. The lead compound was subjected to structural optimization through rational chemical modifications, in order to improve its potency and bioavailability

Two-Color Surface Photometry of Brightest Cluster Members

The Gunn g, r and i CCD images of a representative sample of 17 Brightest Cluster Galaxies (BCM) have been analyzed in order to derive surface brightness and color profiles, together with geometrical parameters like eccentricity and position angle. The sample includes both X-ray and optically selected clusters, ranging in redshift from z=0.049 to z=0.191. We find that BCMs are substantially well described by de Vaucouleurs' law out to radii of $\sim 60-80$ kpc, and that color gradients are generally absent. Only in two cases we find a surface brightness excess with respect to the $r^{1/4}$ law, which for A150 is coupled with a change in the $g-r$ color. The rest frame colors of BCMs do not show any intrinsic dispersion. By parametrizing the environment with the local galaxy number density, we find that it is correlated with the BCM extension, i.e. BCMs with larger effective radii are found in denser environments.Comment: accepted for publication in Aj, May 1997, 25 pages LaTeX format (aas style files), including tables, plus 6 figures (postscript

Neurophysiological Profile of Antismoking Campaigns

Over the past few decades, antismoking public service announcements (PSAs) have been used by governments to promote healthy behaviours in citizens, for instance, against drinking before the drive and against smoke. Effectiveness of such PSAs has been suggested especially for young persons. By now, PSAs efficacy is still mainly assessed through traditional methods (questionnaires and metrics) and could be performed only after the PSAs broadcasting, leading to waste of economic resources and time in the case of Ineffective PSAs. One possible countermeasure to such ineffective use of PSAs could be promoted by the evaluation of the cerebral reaction to the PSA of particular segments of population (e.g., old, young, and heavy smokers). In addition, it is crucial to gather such cerebral activity in front of PSAs that have been assessed to be effective against smoke (Effective PSAs), comparing results to the cerebral reactions to PSAs that have been certified to be not effective (Ineffective PSAs). &e eventual differences between the cerebral responses toward the two PSA groups will provide crucial information about the possible outcome of new PSAs before to its broadcasting. &is study focused on adult population, by investigating the cerebral reaction to the vision of different PSA images, which have already been shown to be Effective and Ineffective for the promotion of an antismoking behaviour. Results showed how variables as gender and smoking habits can influence the perception of PSA images, and how different communication styles of the antismoking campaigns could facilitate the comprehension of PSA’s message and then enhance the related impac

Antismoking campaigns’ perception and gender differences: a comparison among EEG Indices

Human factors’ aim is to understand and evaluate the interactions between people and tasks, technologies, and environment. Among human factors, it is possible then to include the subjective reaction to external stimuli, due to individual’s characteristics and states of mind. These processes are also involved in the perception of antismoking public service announcements (PSAs), the main tool for governments to contrast the first cause of preventable deaths in the world: tobacco addiction. In the light of that, in the present article, it has been investigated through the comparison of different electroencephalographic (EEG) indices a typical item known to be able of influencing PSA perception, that is gender. In order to investigate the neurophysiological underpinnings of such different perception, we tested two PSAs: one with a female character and one with a male character. Furthermore, the experimental sample was divided into men and women, as well as smokers and nonsmokers. The employed EEG indices were the mental engagement (ME: the ratio between beta activity and the sum of alpha and theta activity); the approach/withdrawal (AW: the frontal alpha asymmetry in the alpha band); and the frontal theta activity and the spectral asymmetry index (SASI: the ratio between beta minus theta and beta plus theta). Results suggested that the ME and the AW presented an opposite trend, with smokers showing higher ME and lower AW than nonsmokers. The ME and the frontal theta also evidenced a statistically significant interaction between the kind of the PSA and the gender of the observers; specifically, women showed higher ME and frontal theta activity for the male character PSA. This study then supports the usefulness of the ME and frontal theta for purposes of PSAs targeting on the basis of gender issues and of the ME and the AW and for purposes of PSAs targeting on the basis of smoking habits

Neurohypophyseal hormones: novel actors of striated muscle development and homeostasis

Since the 1980's, novel functional roles of the neurohypophyseal hormones vasopressin and oxytocin have emerged. Several studies have investigated the effects of these two neurohormones on striated muscle tissues, both in vitro and in vivo. The effects of vasopressin on skeletal myogenic cells, developing muscle and muscle homeostasis have been documented. Oxytocin appears to have a greater influence on cardiomyocite differentiation and heart homeostasis. This review summarizes the studies on these novel roles of the two neurohypophyseal hormones, and open the possibility of new therapeutic approaches for diseases affecting striated muscle