3,900 research outputs found
Paleo-biomechanics and paleo-energetics of cross-country skiing and ice skating (3200 BC to date)
No full textEThOS - Electronic Theses Online ServiceGBUnited Kingdo
The first humans travelling on ice: an energy-saving strategy?
Full text linkEconomy of locomotion is a constant challenge for animals, particularly when related to migrations and travelling. The present study focuses on human locomotion and particularly on the development of ice skating. The aim of our research was to understand whether an environmental feature such as a strong presence of lakes (frozen in winter) could force humans to develop ice skates in order to limit the energy cost of travelling. We hypothesized that the energy-saving principle was a determinant factor in the development of human locomotion on ice. Five healthy adult participants took part in the experiments, during which we recorded the speed (1.2 ± 0.3 m s−1) and metabolic energy cost (4.6 ± 0.9 J kg−1 m−1) associated with travelling on bone skates. Simulations were also performed to demonstrate whether the benefit given by the use of skates was different in the areas where ice skating appears to have evolved originally. The gain reachable by using bone skates could lead to an extremely high energy saving (equal to 10% of the energy needed to survive during the cold season) and differs significantly between the regions considered in the present study. An analysis of the geometrical shape of lakes associated with fractal analysis of their distribution suggests that, in order to better adapt to the severe conditions imposed by the long lasting winters, Finnish populations could benefit more than others from developing this ingenious locomotion tool. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 93, 1–7
Il ruolo della mobilità attiva per l’Urbanistica preventiva: uno studio sperimentale nell’area di Udine
No full textCongestione veicolare ed emissioni rappresentano indicatori primari nelle scelte della pianificazione dei trasporti e della mobilità sostenibile. La bicicletta può rivestire un ruolo chiave sia per la transizione ecologica del trasporto privato sia per mantenere uno stile di vita attivo ma è ancora scarsa l’evidenza scientifica dell’efficacia che ciò può apportare alla salute individuale e pubblica. In un contesto urbano e peri-urbano come quello di Udine che consente l’uso della bicicletta di tipo sistemico su tratte singole di ~4 km per ~16 min di percorrenza sono state condotte misurazioni sperimentali facendo un confronto trasversale tra un gruppo di partecipanti attivi che usano prevalentemente la bici come mezzo di trasporto con un gruppo di partecipanti sedentari che usavano l’auto. Tali misurazioni sono state ripetute dopo 24 settimane in un sottogruppo di partecipanti che hanno cambiato il mezzo di trasporto a favore della bicicletta. I risultati emersi portano alla conclusione che, nel contesto considerato e per le caratteristiche del gruppo, il pendolarismo su bicicletta è associato ad una maggior capacità di esercizio, una miglior funzione microvascolare e ridotte emissioni di CO2 in atmosfera. Le distanze e tempi di percorrenza medi di questo studio possono servire da indicatori per una pianificazione della mobilità attiva consapevole nel supportare uno stile di vita attivo utile a prevenire le malattie legate a inattività
Milano consolato nell' elettione a questo arciuescouado, e promotione alla sagra porpora dell' eminentissimo Federico Visconti : colla sua solennissima entrata seguita a' 11. genaro 1682 e fontioni antecedenti /
No full textFrontispiece coat of arms of Milan, engraved by Federico Agnelli.Signatures: pi⁴ A-G⁴ H⁴(-H4).Mode of access: Internet.Binding: limp vellum. Author & title written on spine
Dall'incuria alla cura. Premesse per introdurre l'autobiografia in carcere
No full textCome progettare un intervento formativo e di cura educativa in luoghi di reclusione? Il contributo nasce da un gruppo di lavoro coordinato da Laura Formenti che, in un arco di un anno, ha analizzato e sviluppato i significati della cura educativa attraverso la narrazione e la scrittura autobiografica, all'interno di contesti educativi di tipo formale e non formale
Human locomotion on ice: the evolution of ice-skating energetics through history.
No full textMore than 3000 years ago, peoples living in the cold North European regions started developing tools such as ice skates that allowed them to travel on frozen lakes. We show here which technical and technological changes determined the main steps in the evolution of ice-skating performance over its long history. An in-depth historical research helped identify the skates displaying significantly different features from previous models and that could consequently determine a better performance in terms of speed and energy demand. Five pairs of ice skates were tested, from the bone-skates, dated about 1800 BC, to modern ones. This paper provides evidence for the fact that the metabolic cost of locomotion on ice decreased dramatically through history, the metabolic cost of modern ice-skating being only 25% of that associated with the use of bone-skates. Moreover, for the same metabolic power, nowadays skaters can achieve speeds four times higher than their ancestors could. In the range of speeds considered, the cost of travelling on ice was speed independent for each skate model, as for running. This latter finding, combined with the accepted relationship between time of exhaustion and the sustainable fraction of metabolic power, gives the opportunity to estimate the maximum skating speed according to the distance travelled. Ice skates were probably the first human powered locomotion tools to take the maximum advantage from the biomechanical properties of the muscular system: even when travelling at relatively high speeds, the skating movement pattern required muscles to shorten slowly so that they could also develop a considerable amount of force
»It contained harbours that pleased me like sonnets«. Kleine Poetik der diegetischen Karte
No full textIn this article, Federico Italiano explores the relationship between literature and cartography. Beginning with Stevenson’s Treasure Island, the author frames the topic through a general theoretical lens on the spatial dimension of literary texts. He then focuses on a specific phenomenon of literary "carticity"—the diegetic presence of the map, that is, the map as an integral element of the narrative structure. Among others, Italiano examines the works of Houellebecq and Cormac McCarthy
Pathophysiology of coronavirus-19 disease acute lung injury
No full textPurpose of review More than 230 million people have tested positive for severe acute respiratory syndrome-coronavirus-2 infection globally by September 2021. The infection affects primarily the function of the respiratory system, where ~20% of infected individuals develop coronavirus-19 disease (COVID-19) pneumonia. This review provides an update on the pathophysiology of the COVID-19 acute lung injury. Recent findings In patients with COVID-19 pneumonia admitted to the intensive care unit, the PaO2/FiO2 ratio is typically <26.7kPa (200mmHg), whereas lung volume appears relatively unchanged. This hypoxaemia is likely determined by a heterogeneous mismatch of pulmonary ventilation and perfusion, mainly associated with immunothrombosis, endothelialitis and neovascularisation. During the disease, lung weight, elastance and dead space can increase, affecting respiratory drive, effort and dyspnoea. In some severe cases, COVID-19 pneumonia may lead to irreversible pulmonary fibrosis. Summary This review summarises the fundamental pathophysiological features of COVID-19 in the context of the respiratory system. It provides an overview of the key clinical manifestations of COVID-19 pneumonia, including gas exchange impairment, altered pulmonary mechanics and implications of abnormal chemical and mechanical stimuli. It also critically discusses the clinical implications for mechanical ventilation therapy.</p
- …
