La diffusione del doping nello sport amatoriale: domanda, offerta, prevenzione.

Obiettivo di questo elaborato è studiare le caratteristiche principali del fenomeno doping nello sport amatoriale e le ragioni che sottostanno alla sua sempre più capillare diffusione; cercare di ricostruire il mercato illecito delle sostanze dopanti individuando, quanto più precisamente possibile, gli attori della domanda e dell'offerta; presentare infine le moderne strategie di contrasto e prevenzione, individuandone le criticità e valutando possibili linee di intervento future. Nel capitolo intitolato "Doping e salute" viene brevemente introdotto il problema generale dell'abuso consumistico di farmaci, pratica che risulta ormai estremamente diffusa in ambito sportivo, e vengono elencate e descritte in sintesi le sostanze più frequentemente utilizzate per migliorare le prestazioni. Il capitolo successivo, intitolato "Le varie facce del doping", propone un'analisi completa del mercato delle sostanze proibite: la domanda di doping viene indagata nelle sue principali sfaccettature, dalla moderna società iper-medicalizzata alla domanda di sostanze proibite in Italia, estremamente significativa presso gli sportivi amatoriali; l'offerta di doping viene analizzata considerando tutta la filiera commerciale, dai suppliers ai traffici che alimentano il mercato illecito; la parte finale del capitolo presenta i trend che hanno caratterizzato il fenomeno doping in Italia nel periodo 2003-2014 ed espone le principali criticità dei dati statistici ufficiali. Il capitolo intitolato "Prevenzione: limiti e possibili linee di intervento", evidenzia le problematiche delle attività di contrasto alla diffusione del doping, esponendo la necessità di investire in oculate campagne di comunicazione, di collaborare con medici ed operatori sanitari e di valorizzare l'attività formativa di scuola e famiglia, così da trasmettere ai giovani la cultura di uno sport pulito ed i valori di uno stile di vita sano; descrive inoltre il triplice approccio con cui la Commissione europea affronta il problema doping e propone un resoconto dei principali studi in materia condotti nel nostro paese attorno agli anni 2000: si tratta di iniziative finalizzate alla prevenzione che offrono anche molti spunti per valutare caratteristiche ed entità del fenomeno doping in Italia. Il capitolo finale della tesi, intitolato "Conclusioni", consiste in un sintetico riepilogo delle questioni precedentemente affrontate ed espone le principali migliorie che, in base ai più recenti dibattiti sull'argomento, possono essere approntate alla lotta contro il doping

CIRCADIAN CONTROL OF VISUAL INFORMATION-PROCESSING IN THE OPTIC LOBE OF THE GIANT COCKROACH BLABERUS-GIGANTEUS

Extracellular spike activity from three different types of visual interneurons found in the optic lobe of the giant cockroach Blaberus giganteus was recorded. The spike rate of all three types of neurons fluctuated in a circadian manner in constant darkness (DD). Two types, so-called ''on'' neurons (ON1 and ON2), responded exclusively to stationary light stimuli. A static light pulse elicited a sustained component in ON1, whereas in ON2 only a brief transient response was observed. In ON1 neurons, responsiveness was high during the subjective night and low during the subjective day. The responsiveness of ON2 neurons had a peak during a few hours around subjective dusk and a smaller peak in the later subjective night. The third neuron type recorded consisted of a directionally selective motion-detecting (DSMD) neuron. The pure intensity response and the motion response of the DSMD neuron were high during the subjective day and low during the subjective night. The results show that visual interneurons in the optic lobes are influenced differently by the circadian oscillator system. It is suggested that the mode of circadian control depends on the role a neuron plays in the process of visual information processing

RESPONSE CHARACTERISTICS OF WIDE-FIELD NON-HABITUATING NON-DIRECTIONAL MOTION DETECTING NEURONS IN THE OPTIC LOBE OF THE LOCUST, LOCUSTA-MIGRATORIA

1. Extracellular recordings from wide-field non-habituating non-directional (ND) motion detecting neurons in the second optic chiasma of the locust Locusta migrator ia are presented. The responses to various types of stepwise moving spot and bar stimuli were monitored (Fig.1). 2. Stepwise motion in all directions elicited bursts of spikes. The response is inhibited at stimulus velocities above 5 degrees/s. At velocities above 10 degrees/s the ND neurons are slightly more sensitive to motion in the horizontal direction than to motion in the vertical direction (Fig. 2). The ND cells have a preference for small moving stimuli (Fig. 3). 3. The motion response has two peaks. The latency of the second peak depends on stimulus size and stimulus velocity. Increasing the height from 0.1 to 23.5 degrees of a 5 degrees/s moving bar results in a lowering of this latency time from 176 to 130 ms (Fig. 4). When the velocity from a single 0.1 degrees spot is increased from 1 to 16 degrees/s, the latency decreases from 282 to 180 ms (Figs. 5-6). 4. A change-of-direction sensitivity is displayed. Stepwise motion in one particular direction produces a continuous burst of spike discharges. Reversal or change in direction leads to an inhibition of the response (Fig. 7). 5. It shows that non-directional motion perception of the wide-field ND cells can simply be explained by combining self- and lateral inhibition

A STATISTICAL CORRELATION TECHNIQUE AND A NEURAL-NETWORK FOR THE MOTION CORRESPONDENCE PROBLEM

A statistical correlation technique (SCT) and two variants of a neural network are presented to solve the motion correspondence problem. Solutions of the motion correspondence problem aim to maintain the identities of individuated elements as they move. In a preprocessing stage, two snapshots of a moving scene are convoluted with two-dimensional Gabor functions, which yields orientations and spatial frequencies of the snapshots at every position. In this paper these properties are used to extract, respectively, the attributes orientation, size and position of line segments. The SCT uses cross-correlations to find the correct translation components, angle of rotation and scaling factor. These parameters are then used in combination with the positions of the line segments to calculate the centre of motion. When all of these parameters are known, the new positions of the line segments from the first snapshot can be calculated and compared to the features in the second snapshot. This yields the solution of the motion correspondence problem. Since the SCT is an indirect way of solving the problem, the principles of the technique are implemented in interactive activation and competition neural networks. With boundary problems and noise these networks perform better than the SCT. They also have the advantage that at every stage of the calculations the best candidates for corresponding pairs of line segments are known