1,721,064 research outputs found
Ergodicity of a class of truncated elliptical billiards
Full text linkWe consider a class of billiard tables obtained by intersecting elliptical domains x2/a2 + y2 ≤ 1, a > 1 with horizontal strips |y| ≤ h < 1. The boundary of these tables consists of two elliptical arcs connected by two parallel straight segments. We prove that the billiards in these tables have non-vanishing Lyapunov exponents for h < min(1/a, 1/√2), and are ergodic for h < 1/√1 +a2
A local ergodic theorem for non-uniformly hyperbolic symplectic maps with singularities
Full text linkIn this paper, we prove a criterion for the local ergodicity of non-uniformly hyperbolic symplectic maps with singularities. Our result is an extension of a theorem of Liverani and Wojtkowski
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Semi-focusing billiards: ergodicity
Full text linkIn Bunimovich and Del Magno [Semi-focusing billiards: hyperbolicity. Comm. Math. Phys. 262 (2006), 1732], we proved that billiards in certain three-dimensional convex domains are hyperbolic. In this paper, we continue the study of these systems, and prove that they enjoy the Bernoulli property. This result answers affirmatively a long-standing question on the existence of ergodic billiards in convex domains in dimensions greater than two. Besides, it shows that the chaotic components of the first rigorously investigated three-dimensional billiards with mixed phase space (mushroom billiards), introduced in Bunimovich and Del Magno, are in fact Bernoulli
Augusto Bonome and his revolutionary studies on leprosy in the early 20th century
Full text linkBackground: Augusto Bonome (1857-1922), professor at the University of Padua until 1922, was involved in a study about a particular kind of pulmonary leprosy, being the first to testify the lepromatous alterations also in the deepest parts of the respiratory tract, even though the same Gerhard Hansen (1841-1912) had denied the possibility that lungs could host Mycobacterium leprae. Objectives: It is necessary to reevaluate the research done by Bonome to also demonstrate how it can still be relevant today in further comprehension of leprosy. Methods: Bonome's advances in leprosy studies are testified by some specimens from the Morgagni Museum of Pathological Anatomy of the University of Padua. Among the specimens, there is a peculiar case of advanced tuberous leprosy in an adolescent, who died in 1908, of which the face, the larynx, the hands and genitals are still preserved today in the Museum. Results: Through autoptic and histological analysis of this specimen, Bonome succeeded in identifying a peculiar case of bone toxoid-infectious dystrophy besides characteristic leprous laryngitis, which caused the death of the young leprosy patient. Conclusions: The results confirmed the innovative research carried on by Bonome during his medical career, being among the first to offer an important contribution to improving and revolutionary knowledge on leprosy which could still be useful today
Lodovico Brunetti, the Unknown Father of Modern Crematorium
No full textThe cremation has been documented since prehistoric times and it was a common funerary custom until the advent of Catholicism. Falling into disuse, during XVII–XVIII centuries there were new movements to bring it back according to modern criteria, mainly due to hygienic reasons and cemeteries overcrowding. This also led to the prototyping of new crematory ovens to improve the ancient open-air pyre. Lodovico Brunetti was the first to carry out a crematory experimental research in the modern countries. Since Brunetti's studies were based on the study of ancient cremations, a comparison with a modern experience of reconstruction of archaeological cremation is presented to evaluate the validity of his crematorium oven. Furthermore, the social and religious aspects related to Brunetti's inventions and the revitalization of cremation shows how tools and technologies and also the cultural environment have evolved over the years, effectively accepting the cremation practice as an alternative to inhumation
Semi-focusing billiards: Hyperbolicity
Full text linkIn this paper we answer affirmatively the question concerning the existence of hyperbolic billiards in convex domains of R3. We also prove that a related class of semi-focusing billiards has mixed dynamics, i.e., their phase space is an union of two invariant sets of positive measure such that the dynamics is integrable on one set and is hyperbolic on the other. These billiards are the first rigorous examples of billiards in domains of R3 with divided phase space
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