813 research outputs found
Correction to: Pediatric elbow arthroscopy: clinical outcomes and complications after long-term follow-up (Journal of Orthopaedics and Traumatology, (2021), 22, 1, (55), 10.1186/s10195-021-00619-2)
No full textFollowing publication of the original article [1], the authors identified an error in the author names. The given name and family name were erroneously transposed. The incorrect author names: Micheloni Gian Mario, Tarallo Luigi, Negri Alberto, Giorgini Andrea, Merolla Giovanni and Porcellini Giuseppe. The correct author names: Gian Mario Micheloni, Luigi Tarallo, Alberto Negri, Andrea Giorgini, Giovanni Merolla, Giuseppe Porcellini. The author group has been updated above and the original article [1] has been corrected
Human-Mechanical system interaction in Virtual Reality
No full textThe present work aims to show the great potential of Virtual Reality (VR) technologies in the field of Human-Robot Interaction (HRI).
Indeed, it is foreseeable that in not too distant future cooperating robots will be increasingly present in human environments.
Many authors actually believe that after the current information revolution, we will witness the so-called "robotics revolution", with the spread of increasingly intelligent and autonomous robots capable of moving into our own environments.
Since these machines must be able to interact with human beings in a safe way, new design tools for the study of Human-Robot Interaction (HRI) are needed. The author believes that VR is an ideal design tool for the study of the interaction between humans and automatic machines, since it allows the designers to interact in real-time with virtual robotic systems and to evaluate different control algorithms, without the need of physical prototypes. This also shields the user from any risk related to the physical experimentation.
However, VR technologies have also a more immediate application in the field of HRI, such as the study of usability of interfaces for real-time controlled robots. In fact, these robots, such as robots for microsurgery or even "teleoperated" robots working in a hostile environments, are already quite common. VR allows the designers to evaluate the usability of such interfaces by relating their physical input with a virtual output.
In particular, the author has developed a new software application aimed at simulating automatic robots and, more generally, mechanical systems in a virtual environment. The user can interact with one or more virtual manipulators and also control them in real-time by means of several input devices.
Finally, an innovative approach to the modeling and control of a humanoid robot with high degree of redundancy is discussed.
VR implementation of a virtual humanoid is useful for the study of both humanoid robots and human beings
Almost periodic equations and conditions of Ambrosetti-Prodi type
No full textWe discuss the exact number of almost periodic solutions of certain ordinary differential equations of the second order. The class of equations under consideration is inspired by a well-known result in the area of elliptic boundary value problems
Almost periodic linear differential equations with non-separated solutions
No full textAbstractA celebrated result by Favard states that, for certain almost periodic linear differential systems, the existence of a bounded solution implies the existence of an almost periodic solution. A key assumption in this result is the separation among bounded solutions. Here we prove a theorem of anti-Favard type: if there are bounded solutions which are non-separated (in a strong sense) sometimes almost periodic solutions do not exist. Strongly non-separated solutions appear when the associated homogeneous system has homoclinic solutions. This point of view unifies two fascinating examples by Zhikov–Levitan and Johnson for the scalar case. Our construction uses the ideas of Zhikov–Levitan together with the theory of characters in topological groups
Almost periodic upper and lower solutions
No full textAbstractThe method of upper and lower solutions is a classical tool in the theory of periodic differential equations of the second order. We show that this method does not have a direct extension to almost periodic equations. To do this we construct equations of this type without almost periodic solutions but having two constants as ordered upper and lower solutions
Por uma Sociolinguística Românica “Paramétrica” – relendo Tarallo 1987 e virando a página/ “‘For a ‘Parametric’ Romance Sociolinguistics” – revisiting Tarallo 1987 and turning the page
No full textResumo: Este trabalho revisita a proposta de Tarallo, feita em 1987, que observou os resultados de pesquisas variacionistas (WEINREICH; LABOV; HERZOG, 1968) à luz da Teoria de Princípios e Parâmetros (CHOMSKY, 1981), num momento em que esse modelo começava a se desenvolver. A proposta, tida como herética, já que a Teoria Gerativa não olhava, naquele momento, para a mudança linguística (e nem deveria olhar, visto que naquele momento buscava depreender os princípios invariáveis da Gramática Universal), acabou por se mostrar importante no estudo da mudança sintática no português brasileiro, uma vez que os dois modelos teóricos não estavam competindo, mas se complementando. Além de rever a proposta de Tarallo, que tem contribuído para o estudo da mudança sintática, mostramos como se desenvolve uma pesquisa em Sociolinguística utilizando como componente teórico a teoria de Princípios e Parâmetros. Mostramos ainda que os resultados dessa associação, posta em prática no Brasil a partir dos trabalhos de Tarallo e Kato e seus orientandos, e aqui ilustrados por uma análise contrastiva do português europeu e brasileiro contemporâneos, têm sido reconhecidos por eminentes gerativistas interessados no curso da mudança linguística de longa duração.Palavras-chave: variação e mudança linguística; teoria de princípios e parâmetros; sociolinguística românica paramétrica; Fernando Tarallo; sujeito nulo; análise contrastiva PB-PE.Abstract: This article revisits Tarallo´s (1987) proposal observing variationist results, using the Theory of Language Variation and Change (WEINREICH; LABOV; HERZOG, 1968) in the light of the emerging Principles and Parameters Theory (CHOMSKY, 1981). His proposal, then considered heretical, because generative theory was not concerned about language change then (and it should not have been, because its interest then was then to find invariable principles of Universal Grammar), ended up as an important tool to study syntactic change in Brazilian Portuguese. We would soon realize that the two models were not in competition; on the contrary, they were complementary: the Theory of Language Variation and Change had to be associated with a linguistic theory. As an example of such association, proposed by Tarallo and continued with his work with Mary Kato and their students, we present the advantages of this combination in a contemporary analysis of Brazilian and European Portuguese, recognized by eminent generativists as an important tool to pursue the syntactic change in the long term.Keywords: language variation and change; principles and parameters theory; parametric romance sociolinguistics; Fernando Tarallo; contrastive analysis BP-EP
Massera’s theorem for quasi-periodic differential equations
No full textAbstract. For a scalar, first order ordinary differential equation which depends periodically on time, Massera’s Theorem says that the existence of a bounded solution implies the existence of a periodic solution. Though the statement is false when periodicity is replaced by quasi-periodicity, solu-tions with some kind of recurrence are anyway expected when the equation is quasi-periodic in time. Indeed we first prove that the existence of a bounded solution implies the existence of a solution which is quasi-periodic in a weak sense. The partial differential equation, having our original equa-tion as its equation of characteristics, plays a key role in the introduction of this notion of weak quasi-periodicity. Then we compare our approach with others already known in the literature. Finally, we give an explicit example of the weak case, and an extension to higher dimension for a special class of equations. 1
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