40 research outputs found

    Innovative Higher Education Approaches for Power System Courses

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    Higher education plays a crucial role in modern society and in emerging energy systems, due to the rising complexity of the phenomena and the interplay among various layers (physical, cyber, social and economic). To cope with this context, universities need to develop new visions and tools for education and training. Real-time simulation (RTS) is emerging as a novel and effective approach to analyzing power system aspects, and this characteristic can be effectively used in power system courses. Hence, after the presentation of the basics about the RTS, the paper will show the advantages of employing RTS for teaching activities. Finally, two examples of didactic activities involving RTS at Politecnico di Torino will be presented. In fact, RTS is part of both multi-disciplinary projects (where students with different backgrounds can face the issues affecting the protection and control of power systems) and the course “Electrical systems and safety”, where RTS is used to study the behavior of voltage transformers in saturation

    Symptom dimensions stability over time in recent onset psychosis: A prospective study.

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    The factorial structure of schizophrenia symptoms has been much debated but little is known on its degree of unicity, specificity as well as its dynamic over time. Symptom differentiation is a phenomenon according to which patients' symptoms could differentiate from one another during illness to form more independent, distinct dimensions. On the contrary, symptom dedifferentiation is an increase in the correlations between those symptoms over time. The goal of this study was to investigate symptom differentiation or dedifferentiation over time in recent onset psychosis using the Positive and Negative Syndrome Scale. A confirmatory factor analysis model based on the consensus five-factor model of the Positive and Negative Syndrome Scale for schizophrenia was estimated on seven different time points over a three-year period. A general factor capturing common variance between every symptom was also included. Explained common variance was computed for the general factor and each specific factor. Three hundred and sixty-two recent onset psychosis patients were assessed. Results showed no evidence for either symptom differentiation or dedifferentiation over time. Specific symptoms accounted for >70 % of the variance suggesting a high degree of specificity of the symptomatology. Overall, this study adds support for a highly multidimensional approach to clinical symptom assessment with an explicit focus on depression. The premise behind the staging approach being inherently one-dimensional, implications for further research is discussed

    Age at the time of onset of psychosis: A marker of specific needs rather than a determinant of outcome?

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    While there is suggestion that early onset of psychosis is a determinant of outcome; knowledge regarding correlates of later onset age is more limited. This study explores the characteristics of patients developing psychosis after age 26, towards the end of the usual age range of early intervention programs, in order to identify potential specific needs of such patients. Two hundred and fifty-six early psychosis patients aged 18-35 were followed-up prospectively over 36 months. Patients with onset after 26 ("later onset", LO) were compared to the rest of the sample. LO patients (32% of the sample) had shorter DUP, were less likely to be male, had better premorbid functioning and were more likely to have been exposed to trauma. They had greater insight at presentation and less negative symptoms overall. The trajectories for positive and depressive symptoms were similar in both groups. Evolution of functional level was similar in both groups, but while LO patients recovered faster, they were significantly less likely to return to premorbid functional level. Later psychosis onset correlates with better premorbid functioning and higher rate of trauma exposure; the latter should therefore be a treatment focus in such patients. LO patients were less likely to return to premorbid functional level, which suggests that current treatment strategies may not be efficient to help patients maintain employment. The possibility of distinct illness mechanisms according to onset age and the more central role for trauma in patients with onset after age 26 needs to be further explored

    Laboratory study of the orientation mechanisms of f. pratensis retz. (hymenoptera, formicidae).

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    Ants are able to repeatedly reach a fixed point in the environment by means of external and/or internal orientation references. The orientation mechanisms of workers of F. pratensis was studied in laboratory controlled conditions. The video-recorded experiment involved a base configuration in which the workers associated the position of the food source with that of a visual signal. The experimental sessions involved a change of some variables (food source, visual and chemical signals) and measurement of the number of ants arriving at two platforms associated with the visual signals. The data were analysed by the χ2-test. Our study shows that chemical signal is an information able to change the behaviour of F. pratensis workers. To better understand the importance of visual and idiothetic information instead, further investigation will be necessary

    Competition for foraging resources and coexistence of two syntopic species of Messor harvester ants in Mediterranean grassland.

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    1. Diet composition of two syntopic species of Messor seed-harvester ants (M. wasmanni Krausse and M. minor Andre) was evaluated during different periods over the year (May, July, October), by analysing food type (plant parts and species) and food size (weight, length, width). Morphological traits of foragers (head width and femur length) considered important features promoting diet partitioning were measured. 2. We used two robust randomisation algorithms (RA2 and RA3), adopted in niche overlap studies, to check for random vs non random utilisation of resources at intra- and interspecific level for the different periods. 3. Analyses showed high levels of overlap in the diet of the two species and no evidence of interspecific competition during most of the activity season. In particular, there was an aggregated use of resources in summer, whilst niche partitioning and evidence of competition when resources decreased in autumn. Intraspecifically, no evidence of competition was found. 4. Results suggest two different mechanisms for minimising competition: when food resources are abundant (summer), ants collected the same plant species but selected different sizes; when food resource is scarce (autumn), ants foraged on different plants. 5. The importance of different factors (morphological, behavioural, ecological) possibly affecting competition and coexistence are discussed

    Spatio-temporal foraging dynamics in two coexisting harvester ants of genus Messor (Hymenoptera Formicidae).

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    Different aspects of the foraging strategies of two harvester ant species, Messor wasmanni and M. minor, were investigated in a Mediterranean dry grassland area. Baits were used to evaluate the existence of a trade-off between resource discovery and domination as well as the effect of three variables (air temperature, relative humidity and distance) on the trade-off. Baits were also utilized to explore random vs non random use of time by colonies. Random vs non random utilization of space was instead evaluated by mapping the daily foraging area of colonies in a grid of 900 plots of 1 m2 each. Results revealed that species coexistence is not preferentially supported by a trade-off in resource utilization with no overall effect of the examined variables. The foraging activity of the two species widely overlapped whilst a clear competition for space occurred. The observed space partitioning could represent an advantageous strategy for the coexistence of the two ant species. © 2014 Springer Science+Business Media New York

    Spatio-temporal foraging dynamics in two coexisting harvester ants of genus Messor (Hymenoptera Formicidae).

    No full text
    Different aspects of the foraging strategies of two harvester ant species, Messor wasmanni and M. minor, were investigated in a Mediterranean dry grassland area. Baits were used to evaluate the existence of a trade-off between resource discovery and domination as well as the effect of three variables (air temperature, relative humidity and distance) on the trade-off. Baits were also utilized to explore random vs non random use of time by colonies. Random vs non random utilization of space was instead evaluated by mapping the daily foraging area of colonies in a grid of 900 plots of 1 m2 each. Results revealed that species coexistence is not preferentially supported by a trade-off in resource utilization with no overall effect of the examined variables. The foraging activity of the two species widely overlapped whilst a clear competition for space occurred. The observed space partitioning could represent an advantageous strategy for the coexistence of the two ant species. © 2014 Springer Science+Business Media New York
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