96 research outputs found
Violent relaxation in phase-space
No full textThe problem of violent relaxation mechanism in collisionless systems from the point of view of the distribution function (DF) in μ-space is reviewed. The literature run starts from the seminal paper of Lynden-Bell [Lynden-Bell, D., 1967. MNRAS 136, 101] and is closed by that of the same author [Arad, I., Lynden-Bell, D., 2005. MNRAS 361, 385]. After some introductive sections on the stellar dynamical equilibria and on the Shannon’s information theory, the different approaches follow each accompanied with its criticism on the previous works. Different coarse-grained DFs proposed by different authors have been taken into account. It appears that for a collisionless gas of a unique mass specie there is not significant discrepancies among the different approaches which converge to the same DF at the end of relaxation process. The main problem is to avoid the non observed mass segregation in the case of multi-species composition, e.g., in a star-dominated galaxy component. On this topic the results are very different and are depending on the shape and size one chooses for μ-space tiles. A great effort has been spent into the visualization of the different partitions in phase-space in order to understand clearly from what the differences arise
VR-Wheel: a Rehabilitation Platform for Motor Recovery
No full textIn this paper we introduce VR-Wheel, a
platform combining cognitive and motor-learning tasks,
intended for motor recovery in lower limb amputee and
tetraplegic patients in post-traumatic conditions. The main
feature of the platform is its versatility from the biomechanical,
hardware and software viewpoint, since the design of the
application is such that patients’ own wheelchairs are
transformed into an USB mouse, interfaced with any types of
mouse-drivable graphics and/or software and any kind of
operative system. The mechanics is flexible and the dedicated
VR-environment is user friendly and easily tunable to different,
specific clinical requirements. In this paper we present its
general design and some scenarios for its clinical use
Long-distance monitoring of physiological and environmental parameters for emergency operators
No full textThe recent disaster provoked by the earthquake in middle Italy has pointed out the need for minimizing risks endangering rescuers' lives. An European Project called ProeTEX (Protection e-Textiles: MicroNanoStructured fiber systems for Emergency-Disaster Wear) aims at developing smart garments able to monitor physiological and environmental parameters of emergency operators. The goal is to realize a wearable system detecting health state parameters of the users (heart rate, breathing rate, body temperature, blood oxygen saturation, position, activity and posture) and environmental variables (external temperature, presence of toxic gases and heat flux passing through the garments) and remotely transmitting useful information to the operation manager. This work presents an overview of the main features of the second prototype realized by ProeTEX with particular emphasis to the sensor's body network and the long distance transmission of signals
Bio-Inspired Controller for a Dexterous Prosthetic Hand Based on Principal Components Analysis
No full textControlling a dexterous myoelectric prosthetic hand with many degrees of freedom (DoFs) could be a very demanding task, which requires the amputee for high concentration and ability in modulating many different muscular contraction signals. In this work a new approach to multi-DoF control is proposed, which makes use of Principal Component Analysis (PCA) to reduce the DoFs space dimensionality and allow to drive a 15 DoFs hand by means of a 2 DoFs signal. This approach has been tested and properly adapted to work onto the underactuated robotic hand named CyberHand, using mouse cursor coordinates as input signals and a principal components (PCs) matrix taken from the literature. First trials show the feasibility of performing grasps using this method. Further tests with real EMG signals are foreseen
Indian Life in the 1930s as Portrayed in The Surrounded, a Novel by D’Arcy Mc Nickle
No full textA native American author from Montana, James Welch writes about two men suffering from partly desired amnesia. Human beings, animals and the thunder help the narrator of Winter in the Blood to undergo the initiation rites which dispel the mist clouding his memory. The schizophrenic half-breed in The Death of Jim Loney receives visions which he can only decipher thanks to an Indian friend. The merging of their individual memories into the collective memory of their people frees these two anti-heroes from their existential non-being by forcing them to accept their identity as Indians.Dans une analyse de « The Surrounded », premier roman de McNickle, Anna Secco étudie la structure du récit et suggère que l'auteur nous fait comprendre la juxtaposition et l'interaction de deux conceptions du monde. Le héros principal personnifie le besoin indien fondamental de redécouvrir les anciennes croyances.Secco Anna. Indian Life in the 1930s as Portrayed in The Surrounded, a Novel by D’Arcy Mc Nickle. In: Revue Française d'Etudes Américaines, N°38, novembre 1988. L'indianité : contextes et perspectives. pp. 366-368
Lito-poiesi: Per un’antropologia delle capanne in pietra a secco pugliesi
No full textHow to explain the morphological diversity of dry-stone corbelled huts found in Apulia region? Their diversity manifests itself mainly in the outer shell whereas the inner structure remains invariant (corbelling technique, dry-stone technology). In contrast with previous theories, the author indicates with litho-poiesis the fabrication process, not only functional but also symbolic and agentive, which has been carried out, with different degrees of know-how, by the dry-stone builders especially during the 19th century. The different choices and alternatives that the builders had to deal with during the building process, emphasize two ways in which litho-poiesis has manifested itself: 1. A “collective” process that implied the gradual emergence of local aesthetics and that sometimes has given rise to cases of hybridism; 2. A more individualized process within the local community, which implied the close collaboration between the future hut users on one hand and the specialized dry-stone builders on the other hand, in order to create a construction that has the capacity to stand out from the neighboring ones and therefore, thanks to the greater technical virtuosity that characterizes it, communicates to the viewer the higher social status of the respective owner.Come spiegare la diversità morfologica delle costruzioni in pietra a secco che si trovano nella regione Puglia? La loro diversità si manifesta principalmente nell’aspetto esteriore rispetto alla struttura che invece rimane invariante (tholos, tecnologia della pietra a secco). In polemica con le teorie precedenti, l’autore indica con lito-poiesi il processo di fabbricazione non solo funzionale ma anche simbolica e agentiva che ha visto impegnate, con gradi diversi di savoir-faire, le maestranze specie durante il XIX secolo. Le diverse scelte e alternative a cui sono andati incontro i costruttori pongono in evidenza due modalità attraverso cui si è manifestata la lito-poiesi: 1. Un processo “collettivo” che ha visto sorgere progressivamente delle estetiche locali e che a volte ha dato luogo a fenomeni di ibridismo; 2. Un processo interno alla collettività locale e maggiormente individualizzante che ha coinvolto in stretta sinergia i committenti-futuri utilizzatori degli edifici a secco da una parte, e le maestranze specializzate dall’altra, al fine di creare una costruzione che avesse la capacità di distinguersi da quelle limitrofe e che quindi, proprio grazie al maggiore virtuosismo tecnico che la caratterizza, comunicasse lo status sociale più elevato del rispettivo proprietario
Innovation and Knowledge in Agri-food and Environmental Systems
No full textAs noted in the LVIII SIDEA Conference call for paper, in the challenging scenario of deep transformations, uncertainties and turbolences that the European and Italian agri-food and environmental systems are currently facing, the strong links between technological innovation, multi-sectoral sustainability, adaptability and resilience cannot be disregarded. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2024
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