1,722,242 research outputs found
Permittivity tomographic characterization of dielectric materials vs. partial discharge activity
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Dominance relationships in a family pack of captive arctic wolves (Canis lupus arctos): The influence of competition for food, age and sex
Full text linkBackground. Dominance is one of the most pervasive concepts in the study of wolf social behaviour but recently its validity has been questioned. For some authors, the bonds between members of wolf families are better described as parent-offspring relationships and the concept of dominance should be used just to evaluate the social dynamics of non-familial captive pack members (e.g., Mech & Cluff, 2010). However, there is a dearth of studies investigating dominance relationships and its correlates in wolf family packs. Methods. Here, we applied a combination of the most commonly used quantitative methods to evaluate the dominance relationships in a captive family pack of 19 Arctic wolves. Results. We found a significant linear and completely transitive hierarchy based on the direction of submissive behaviours and found that dominance relationships were not influenced by the competitive contexts (feeding vs. non-feeding context). A significant linear hierarchy also emerges amongst siblings once the breeding pair (the two top-ranking individuals) is removed from analyses. Furthermore, results suggest that wolves may use greeting behaviour as a formal signal of subordination. Whereas older wolves were mostly dominant over younger ones, no clear effect of sex was found. However, frequency of agonistic (submissive, dominant and aggressive) behaviours was higher between female-female and male-male dyads than female-male dyads and sex-separated linear hierarchies showed a stronger linearity than the mixed one. Furthermore, dominance status was conveyed through different behavioural categories during intra-sexual and inter-sexual interactions. Discussion. Current results highlight the importance of applying a systematic methodology considering the individuals' age and sex when evaluating the hierarchical structure of a social group. Moreover, they confirm the validity of the concept of dominance relationships in describing the social bonds within a family pack of captive wolves
Tecniche di analisi della fidatezza. FMEA - Analisi dei modi e degli effetti di guasto
No full textIl lavoro presenta una delle più importanti e diffuse tecniche di valutazione della fidatezza. Per l’implementazione dell’analisi occorre disaggregare il sistema secondo una logica di scomposizione per blocchi funzionali, fino a livello di componente
Riprendiamo il tema dopo i "seriali"
No full textIl seriale fino a oggi sviluppato con una serie di articoli si trasforma nella rubrica "Misure e Fidatezza" a dimostrazione del continuo interesse sull'argomento e alla necessità di mantenere attivo un canale di discussione sui temi dell'affidabilità, manutenibilità, disponibilità, rischio e sicurezz
Tecniche di analisi della fidatezza. FMEA -Casi di Studio
No full textIl lavoro mostra, attraverso l’analisi di due casi di studio, i criteri per una corretta applicazione della procedura FMEA. La tecnica – Analisi dei modi e degli effetti di guasto – richiede la conoscenza del sistema e consente di effettuare una valutazione di come un guasto, o il non corretto funzionamento di un componente o di un sottosistema, condizioni le prestazioni del sistema preso in considerazione
Post-conflict opponent affiliation reduces victim re-aggression in a family group of captive arctic wolves (Canis lupus arctos)
Full text linkPost-conflict affiliative interactions have been widely investigated in primates but not extensively in other species. Using the Post Conflict-Matched Control (PC-MC) comparison method, this study investigated the patterns of post-conflict opponent affiliation (POA) of a captive family group of 19 arctic wolves (Canis lupus arctos), investigating the correlation with various factors. We found that POAs occurred mainly in the non-feeding context and more often when the victim was dominant and the aggressor subordinate. Furthermore, POAs were more likely to have been initiated by the victim than the aggressor. Victims’ stress related behaviours occurred more in PC than MC periods, and more after high vs. low intensity aggressions but they were not more likely to occur after conflicts between wolves with a stronger social bond and POAs did not reduce their rate of occurrence. Our results showed that re-aggression was twice less frequent when a friendly interaction occurred between the aggressor and the victim, and consistent with this, victims engaged in POAs more often than the aggressor. Overall, our results support the hypothesis that POAs in wolves may have been selected for as a mechanism to avoid conflict escalation, which could lead to social disruption and hence jeopardize cooperative activities. The high relatedness among individuals in the pack and the greater dependence of all members on cooperation in breeding and hunting may reduce the importance of ‘relationship quality’ as a mediating factor of POAs, although dominance relationships, which are directly linked to the risks of further conflicts, do play an important role
L'affidabilità come requisito di progetto di componenti e sistemi
No full textCon il Diagramma a Blocchi di Affidabilità (RBD) è possibile rappresentare e analizzare sistemi con strutture anche complesse, in condizioni sia di funzionamento che di guasto. In questo articolo vengono presentate e discusse le configurazioni funzionali serie e parallelo, chiamate configurazioni Canoniche. Tali configurazioni consentono di determinare sia un modello matematico dell'affidabilità di sistema che i principali parametri operativi
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