9 research outputs found
Straight running – stability analysis with a driving simulator
No full textThe straight running of the system composed by a car plus driver is studied. Straight running is an important case study for analysing stability. Despite the lateral slip angles of the tyres are small, the system is highly non linear, due essentially to the driver action. Following the simple model of McRuer, later developed by Mistschke and revised by many other authors, we have developed a mathematical model of a car plus driver. The dynamic behaviour of the mathematical model has shown the presence of limit cycles generated by so called Hopf-bifurcations. The mathematical model predicts that, despite the understeering vehicle is globally stable, the driver can make the whole system (car plus driver) unstable. This occurs in case an external disturbance is sufficiently strong. If the external disturbance is small, the understeering vehicle plus driver remains stable. There is a speed above which the understeering car plus driver is unstable, usually such a speed is much greater than the maximum speed of the car on high grip surface. The statements introduced above have been validated by employing the driving simulator of Danisi Engineering, Nichelino, Italy. We experimentally saw that limit cycles do exist and that the driver can make the understeering vehicle model of the simulator quite unstable. We were able to validate the mathematical model by including two humans in the driving loop. One driver was a professional driver, the other one was a novice. The same non linear behaviours were highlighted for the two drivers, however, the amplitudes of the limit cycles and the ability of controlling the car were higher for the professional driver. A question arises whether an electronic power steering (EPS) may reduce or cancel instability. The answer is that there are a number of possible solutions for ESP to counteract the effect of unstable limit cycle
Analytical, numerical and experimental analysis of the non-linear vehicle/driver dynamical system
No full textLAUREA MAGISTRALESulle strade italiane circa il 40.8 % degli incidenti stradali è causato dal guidatore. Per questa ragione, un'analisi del sistema veicolo/guidatore è necessaria per comprendere la causa di comportamenti dinamici instabili e migliorare la sicurezza stradale. Negli ultimi anni un grande sforzo di ricerca nel campo dei veicoli autonomi è stato prodotto. Gli algoritmi che controllano i veicoli autonomi tentano di riprodurre il comportamento del guidatore umano. Perciò lo studio della relazione che intercorre tra guidatore e veicolo e un'analisi dei comportamenti dinamici di questo complesso sistema dinamico è utile anche in questo campo di applicazione. Negli anni molti metodi di analisi dei sistemi non lineari sono stati prodotti, ma tra gli altri, la teoria di biforcazione è l'unica in grado di produrre una panoramica dei comportamenti dinamici del sistema, basandosi sul concetto di equivalenza topologica, variando i parametri caratteristici del sistema. In questo lavoro è stata fatta l'analisi di biforcazione del sistema dinamico non lineare veicolo/guidatore, concentrandosi sulla condizione di marcia in rettilineo. Diverse configurazioni di veicolo sono state studiate ed è stata fatta un'analisi di come varia il comportamento dinamico variando i parametri del guidatore. I risultati ottenuti utilizzando modelli semplificati di veicolo e di guidatore sono stati validati attraverso l'utilizzo di software commerciali (Vi-Grade), in cui la modellizzazione di veicolo e pilota è più accurata e complessa. Si è osservato che l'elemento del sistema veicolo/guidatore che più influenza il comportamento dinamico del sistema è il modello di guidatore. Anche utilizzando i modelli di veicolo e guidatori inclusi nel software commerciale, l'esistenza di una biforcazione di Hopf supercritica per una tipologia di veicolo sottosterzante è stata osservata. Per verificare che i comportamenti dinamici osservati attraverso le analisi numeriche e le simulazioni abbiano un riscontro nella realtà, test sperimentali utilizzando un simulatore di guida dinamico professionale sono stati fatti e i risultati sono stati commentati. Test sul simulatore di guida non sono equivalenti a test effettuati su strada, ma l'esperienza di guida e la riproduzione della dinamica del veicolo sono state validate da piloti professionisti, quindi ci si aspetta che risultati ottenuti attraverso l'utilizzo del simulatore siano molto simili a quelli che verrebbero trovati attraverso test su strada. Basandosi sui risultati ottenuti con questi test sperimentali, l'esistenza di biforcazioni in condizioni simili alla realtà è stata osservata. In particolare sia per veicoli sottosterzanti, sia per veicoli sovrasterzanti, l'esistenza di un ciclo limite instabile è stata validata. Per quanto riguarda il veicolo sovrasterzante, una biforcazione è stata osservata nel range di velocità 40--50 m/s, seguita da un comportamento dinamico caotico. Attraverso questo lavoro l'importanza di valutazioni del comportamento dinamico del sistema veicolo/guidatore utilizzando l'analisi di biforcazione è stata evidenziata e possibili sviluppi di questo lavoro sono proposti nel finale.Almost 40.8 % of road accidents on Italian roads are caused by the driver. An analysis of the complex vehicle/driver system is necessary in order to understand the cause of unstable motions and improve road safety. Furthermore nowadays great research in the field of autonomous driving is done. Autonomous driving algorithms tempt to mimic human driver control behaviour, so a more deep understanding on how the driver and vehicle interact and which dynamical behaviour characterize this system would be useful also in this field of application. Many mathematical methods to study non-linear systems have been developed over the years but, among the others, bifurcation theory is capable to produce a "portrait" of the non-linear system, grouping similar dynamical behaviours by means of using the concept of topological equivalence, varying the system characteristics parameters. In this work bifurcation theory is applied to the non-linear vehicle/driver system, both using analytical methods and numerical methods, focusing on the straight-run condition. Different vehicle configurations are analysed and the influence on the overall dynamical behaviour of the driver parameters is studied. The results obtained by using simple vehicle and driver models are validated by using commercial software (Vi-Grade), in which vehicle and driver models are more accurate and refined. By making this comparison, it has been observed that the component of the vehicle/driver system that influence more the overall vehicle/driver dynamical behaviour is the driver model. Also analysing the Vi-Grade vehicle model coupled with the Vi-Grade driver model, for a validated understeering vehicle, a supercritical Hopf bifurcation has been discovered. To verify that the dynamical behaviours observed using numerical methods and simulations exist in the real world, experimental tests on a professional dynamic driving simulator have been done. The driving simulator is not the reality, but its accuracy in reproducing vehicle dynamics and driving experience have been validated by professional drivers, so it is expected that results obtained with this type of testing are pretty similar to the one that can be obtained on real road tests. Existence of bifurcations has been validated, both using normal and professional drivers. In particular both for understeering both for oversteering vehicles the presence of an unstable limit cycle has been observed. Oversteering vehicles have been shown a bifurcation on a speed range of 40--50 m/s, followed by the establishment of chaotic motions. The importance to assess the dynamical behaviour of the vehicle/driver system by means of bifurcation methodologies has been highlighted and further possible extension of this work are proposed in the conclusion
Diffusioni e visioni
No full textThe Augmented Reality is a technology that allows you to view and to integrate interactive and virtual layer to one reality image produced by the device on which it is integrated: mobile devices and new wearable technologies are predominantly used. During the pre and post medial era, cinema is alway been inclined to face the technological innovations and to be compared with them; nowadays cinema finds itself deeply connected with the digital world on different levels, in order to be hybridated in shape and style. This paper is focused on the audience point of view, in which are getting involved interactivity and participation concepts. The traditional idea of theatre, allows for further considerations about localization and deterritorialization. It gets from an immediate to an ipermediate fruition, even if we remain in immersive and pervasive technologies area of interest. That process inaugurates a scenario in which the user is the new addressee of a new bid, in order to think even more to a plurality of authorship. Diffuse Cinema, is one of the prototype, that is having a fair success margin. It comes to be a cinema, scattered all over the city, that finds out the viewer about the location of the different point of interest. It’s also settled to start a visual performance straight on the screen of the user device, once he turns the connection on. The performatives and experienced characteristic ensure that the bystander becomes for all purposes a spect-actor, willing to plays a role and to cooperate with the urban text, according to personal shape and style, for the purpose to makes the user become, one of the author of story
Temporal perspective and personality styles in argentinean students
No full textEn la Psicología, el concepto de perspectiva temporal, introducido por Lewin (1935), se define como la dirección preferencial de los pensamientos de un sujeto hacia el presente, pasado o futuro, dimensión más o menos estable de la personalidad, que influye sobre la motivación, el pensamiento, y diversos aspectos de su conducta. Zimbardo define el concepto como un proceso no consciente mediante el cual el flujo de las experiencias personales y sociales se encuadran en categorías temporales que ayudan a dar orden, coherencia y significado a esas experiencias y lo operacionaliza, introduciendo también el concepto de perspectiva temporal balanceada (BTP). En este trabajo se presentan los resultados de datos recogidos en una muestra de 329 estudiantes argentinos de nivel medio, terciario (nivel superior no universitario) y universitario, a partir de los que se exploró la posible relación entre perfiles de perspectiva temporal y estilos de personalidad y se evaluó el rol de la perspectiva temporal balanceada en la relación entre ambos constructos. Se aplicó el ZTPI (Inventario de Perspectiva Temporal, Zimbardo & Boyd, 1999), el Cuestionario de Perspectiva Temporal Futura Trascendental (PTFT) (Boyd & Zimbardo, 1997) y el Inventario de Estilos de Personalidad (MIPS, Millon 1994). Los análisis de correlaciones y de variancia arrojan evidencia empírica acerca de las relaciones significativas entre perfiles de Perspectiva temporal y Estilos de personalidad y se verifica, en particular, que hay un perfil de perspectiva temporal más adaptativo que el resto. Se interpretan los resultados como bidireccionales.The time notion has a central place both in the philosophical reflection and in Psychology, indicating a systematical position with regard to the man’s mode of existence in the world. In Psychology, the time perspective concept wasintroduced by Lewin (1935), and defined as the totality of the individual's views of his psychological future and psychological past existing at a given time, a more or lessstable trait of the personality, which influences the motivation, thinking, and various aspects of their behaviour. Zimbardo is the author that more has been busy of the operationalization of this concept, which he defined as a non conscious process through which the flow of personal and social experiences is assigned to temporal categoriesthat help give order, coherence and meaning to those experiences. The relative weight of the time frames introduce considerable differences in the decisions and behaviours and this preference for any of the dimensions can function as a static personality trait that can be non-adaptive. Hence, the authorsintroduce the concept of balanced time perspective (BTP) according to which the present, past and future are combined in a flexible manner, in response to the demands of the times and tasks in the life of the people, as well asto their dominant values. In this work we present the results of data collected in a sample of 329 students ofsecondary, tertiary and university levels, from which explored the possible relationship between profiles of temporal perspective and personality styles in Argentinean students and evaluate the role of balanced temporal perspective in that relationship. The ZTPI (Inventory of Temporal Perspective - Zimbardo & Boyd, 1999), the Questionnaire of Transcendental Future Time Perspective (PTFT - Boyd & Zimbardo, 1997), and the MIPS adaptation to Argentina (Casullo & Castro Solano, 2000) are applied. For the data analysis was used the following statistical: analysis of correlations, analysis of variance (ANOVA one way), tests of significance of the proportional differences and KMeans Cluster Analysis. We used the SPSS.20. Using cluster analysis, three profiles of time perspective and three personality styles are obtained. It is also estimated the deviation of balanced temporal perspective (DBTP) for each subject and three conglomerates were determinated. The correlations and variance analysis show empirical evidence about the meaningful relationships between profiles of temporal perspective and personality styles. It was verified, in particular, that there is a profile of temporal perspective more adaptive than the rest. In fact, 55% of the subjects who are identified with a profile of equilibratetranscendent PT are within the group with open, active, strong and sociable personality stile, while 40% of subjects with conflicting PT are located in the style of conflicted personality. The inclusion of the future transcendental time scale, unified with the ZTPI allows us to see this perspective influences, in particular in the profiles of PT and its relationship with the personality styles. Some of these relationships and their difference with those found by the authors of both scales of PT are interpreted as a result of cultural differences. All the links found are confirmed on the basis of the determination of the balanced time perspective (BTP), which in our sample corresponds to the 28 per cent of the total number of subjects. There would be a two-way relationship, a mutual influence; on the one hand, certain personality traits would glances spreads to the temporal dimensions of the lived and living life and, on the other hand, the profile of temporal perspective that is being consolidated as personality trait refluxes on the rest of the traits, to contribute to the achievement of a identity with greater or lesser degree of adaptation and completeness.Fil: Vázquez, Stella Maris. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; Argentina. Centro de Investigaciones en Antropología Filosófica y Cultural; ArgentinaFil: Difabio, Hilda Emilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; ArgentinaFil: Noriega Biggio, Rina Marianela. Centro de Investigaciones en Antropología Filosófica y Cultural; Argentin
The Omega-3 Fatty Acid Eicosapentaenoic Acid Accelerates Disease Progression in a Model of Amyotrophic Lateral Sclerosis
No full textPMCID: PMC3631166This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
Current models of insomnia disorder: a theoretical review on the potential role of the orexinergic pathway with implications for insomnia treatment
No full textA behavioural and electrophysiological study of factors involved in the relationship between stress and alcohol dependence
No full textAlcohol dependence causes disruption to both work and family life and the associated costs are £150+ million in the UK alone. Stressful life events play a role in initiation of uncontrolled (dependent) drinking and can precipitate relapse to high ethanol consumption after treatment / abstinence. The primary neurological substrate for ethanol reward is the mesolimbic dopamine system of the medial forebrain bundle. Activation of the hypothalamopituitaryadrenal axis (the hormonal response to many stresssors) plays a role in the control of ethanol consumption and relapse, and modulation of neuronal activity by chronic calcium channel blockade decreases ethanol intake, tolerance and withdrawal. The stress system and calcium channel blockade both affect the dopaminergic reward pathways. Hypothesis: Stress and the stress hormone, corticosterone, play a crucial role in the modulation of ethanol consumption and the long term changes resulting from chronic ethanol intake. This hypothesis was tested by investigating the effects of:• social status and calcium channel blockade on chronic ethanol intake (free choice 5, 10, 20% ethanol and water) of group housed rats.• social stress from defeat by an aggressive resident on ethanol preference of low ethanol preference C57 mice.• 6 days abstinence from chronic ethanol intake (liquid diet) on NMDA-stimulated firing of dopaminergic, ventral tegmental area, cells and the role of corticosterone in modulation of this response to NMDA. The main findings from these studies indicate that, while the social stress of group housing under laboratory conditions may be insufficient to elevate ethanol intake, repeated defeat significantly increases ethanol intake. However, neither chronic ethanol consumption nor corticosterone seemd to have any effect on NMDA-stimulated dopamine cell firing. These results indicate a significant role for social stress in the modulation of ethanol intake but possibly not via the action of corticosterone on NMDA-stimulation of the mesolimbic dopamine system
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Neural systems involved in delay and risk assessment in the rat
No full textThis thesis investigated the contribution of the nucleus accumbens core (AcbC) and the hippocampus (H) to choice and learning involving reinforcement that was delayed or unlikely. Animals must frequently act to influence the world even when the reinforcing outcomes of their actions are delayed. Learning with action–outcome delays is a complex problem, and little is known of the neural mechanisms that bridge such delays. Impulsive choice, one aspect of impulsivity, is characterized by an abnormally high preference for small, immediate rewards over larger delayed rewards, and is a feature of attention-deficit/hyperactivity disorder (ADHD), addiction, mania, and certain personality disorders. Furthermore, when animals choose between alternative courses of action, seeking to maximize the benefit obtained, they must also evaluate the likelihood of the available outcomes. Little is known of the neural basis of this process, or what might predispose individuals to be overly conservative or to take risks excessively (avoiding or preferring uncertainty, respectively), but risk taking is another aspect of the personality trait of impulsivity and is a feature of a number of psychiatric disorders, including pathological gambling and some personality disorders.
The AcbC, part of the ventral striatum, is required for normal preference for a large, delayed reward over a small, immediate reward (self-controlled choice) in rats, but the reason for this is unclear. Chapter 3 investigated the role of the AcbC in learning a free-operant instrumental response using delayed reinforcement, performance of a previously learned response for delayed reinforcement, and assessment of the relative magnitudes of two different rewards. Groups of rats with excitotoxic or sham lesions of the AcbC acquired an instrumental response with different delays (0, 10, or 20 s) between the lever-press response and reinforcer delivery. A second (inactive) lever was also present, but responding on it was never reinforced. The delays retarded learning in normal rats. AcbC lesions did not hinder learning in the absence of delays, but AcbC-lesioned rats were impaired in learning when there was a delay, relative to sham-operated controls. Rats were subsequently trained to discriminate reinforcers of different magnitudes. AcbC-lesioned rats were more sensitive to differences in reinforcer magnitude than sham-operated controls, suggesting that the deficit in self-controlled choice previously observed in such rats was a consequence of reduced preference for delayed rewards relative to immediate rewards, not of reduced preference for large rewards relative to small rewards. AcbC lesions also impaired the performance of a previously learned instrumental response in a delay-dependent fashion. These results demonstrate that the AcbC contributes to instrumental learning and performance by bridging delays between subjects’ actions and the ensuing outcomes that reinforce behaviour.
When outcomes are delayed, they may be attributed to the action that caused them, or mistakenly attributed to other stimuli, such as the environmental context. Consequently, animals that are poor at forming context–outcome associations might learn action–outcome associations better with delayed reinforcement than normal animals. The hippocampus contributes to the representation of environmental context, being required for aspects of contextual conditioning. It was therefore hypothesized that animals with H lesions would be better than normal animals at learning to act on the basis of delayed reinforcement. Chapter 4 tested the ability of H-lesioned rats to learn a free-operant instrumental response using delayed reinforcement, and their ability to exhibit self-controlled choice. Rats with sham or excitotoxic H lesions acquired an instrumental response with different delays (0, 10, or 20 s) between the response and reinforcer delivery. H-lesioned rats responded slightly less than sham-operated controls in the absence of delays, but they became better at learning (relative to shams) as the delays increased; delays impaired learning less in H-lesioned rats than in shams. In contrast, lesioned rats exhibited impulsive choice, preferring an immediate, small reward to a delayed, larger reward, even though they preferred the large reward when it was not delayed. These results support the view that the H hinders action–outcome learning with delayed outcomes, perhaps because it promotes the formation of context–outcome associations instead. However, although lesioned rats were better at learning with delayed reinforcement, they were worse at choosing it, suggesting that self-controlled choice and learning with delayed reinforcement tax different psychological processes.
Chapter 5 examined the effects of excitotoxic lesions of the AcbC on probabilistic choice in rats. Rats chose between a single food pellet delivered with certainty (probability p = 1) and four food pellets delivered with varying degrees of uncertainty (p = 1, 0.5, 0.25, 0.125, and 0.0625) in a discrete-trial task, with the large-reinforcer probability decreasing or increasing across the session. Subjects were trained on this task and then received excitotoxic or sham lesions of the AcbC before being retested. After a transient period during which AcbC-lesioned rats exhibited relative indifference between the two alternatives compared to controls, AcbC-lesioned rats came to exhibit risk-averse choice, choosing the large reinforcer less often than controls when it was uncertain, to the extent that they obtained less food as a result. Rats behaved as if indifferent between a single certain pellet and four pellets at p = 0.32 (sham-operated) or at p = 0.70 (AcbC-lesioned) by the end of testing. When the probabilities did not vary across the session, AcbC-lesioned rats and controls strongly preferred the large reinforcer when it was certain, and strongly preferred the small reinforcer when the large reinforcer was very unlikely (p = 0.0625), with no differences between AcbC-lesioned and sham-operated groups. These results suggest that the AcbC contributes to action selection by promoting the choice of uncertain, as well as delayed, reward
Characterisation of T cell defects in acute myeloid leukaemia
No full textPhDUnderstanding the immune system in patients with cancer and how it interacts with malignant cells is critical for the development of successful immunotherapeutic strategies at a time when novel cancer treatment approaches are required. Acute myeloid leukaemia (AML) results in widespread interaction between the malignant cells and T cells and as such, offers an opportunity to study these interactions. A flow cytometric analysis of T cells in the peripheral blood of patients presenting with AML illustrated that the absolute number of T cells is increased in AML compared with healthy controls. Furthermore, a large population of CD3+56+ cells was identified. These cells are not natural killer T cells but effector T cells that may represent a failing immunosurveillance mechanism. Two technical issues were explored: how to separate T cells from the peripheral blood of newly diagnosed AML patients and the impact of the method of immunomagnetic cell separation on the gene expression profile of healthy T cells. Gene expression profiling was subsequently performed on T cells from AML patients compared with healthy controls. Global differences in transcription were observed suggesting aberrant T cell activation patterns in AML. As differentially regulated genes involved in actin cytoskeletal formation were noted, a functional assessment of the ability of T cells from AML patients to form immunological synapses was performed. This illustrated that although T cells from AML patients can form conjugates with autologous blasts, their ability to form immune synapses and recruit phosphotyrosine signalling molecules to that signalling interface is impaired. Taken together, these findings demonstrate that numerically T cells are plentiful in AML however they are abnormal in terms of the genes they are transcribing and in their interactions with tumour cells. Targeting immunological synapse formation may represent an important means of improving T cell recognition of tumour cells across a range of cancers
