Reasoning with Frames and Spacetime Diagrams

Author(s):  
David M. Wittman

To prepare for the high‐speed world where Galilean relativity breaks down, we now practice the skill of thinking in different frames. Practicing this in our familiar lowspeed world will help us avoid cognitive overload when we enter the more counterintuitive high‐speed world. We examine two problems that illustrate the process of thinking in different frames. Te frst is a brain‐teaser that suddenly becomes easier in a particular frame; the second is a classic problem from introductory physics that we can solve in a new way using symmetry and frame‐based thinking tools alone. Along the way, we will learn how to use the spacetime diagram, a major tool that will appear throughout this book. Te chapter concludes with another look at accelerated vs. inertial frames, from the spacetime diagram point of view

Author(s):  
David M. Wittman

To prepare for the high‐speed world where Galilean relativity breaks down, we now practice the skill of thinking in different frames. Practicing this in our familiar lowspeed world will help us avoid cognitive overload when we enter the more counterintuitive high‐speed world. We examine two problems that illustrate the process of thinking in different frames. Te frst is a brain‐teaser that suddenly becomes easier in a particular frame; the second is a classic problem from introductory physics that we can solve in a new way using symmetry and frame-based thinking tools alone. Along the way, we will learn how to use the spacetime diagram, a major tool that will appear throughout this book. Te chapter concludes with another look at accelerated vs. inertial frames, from the spacetime diagram point of view.


2018 ◽  
pp. 145
Author(s):  
Juan Pablo Beca

ResumenEl trabajo analiza el curso Ética Profesional en la carrera de Derecho en la Universidad Católica de Temuco. Examina la forma como se abordaba la ética profesional antes de la creación del curso, y lo que ha ocurrido con él a través de sucesivos cambios curriculares y la introducción del modelo por competencias. El curso aporta al sello identitario, mediante un enfoque multidisciplinario. El curso ha vinculado teoría y práctica, desde que comenzó a implementarse, hasta llegar actualmente a comprenderlo en la lógica de competencias. Esta mirada implica formar a los estudiantes para resolver dilemas éticos, lo que se hace mediante la metodología del ver–juzgar–actuar. Esta metodología de discernimiento es propia de la tradicióncatólica, pero se usa en este contexto sin un cariz religioso. El método en cuestión permite ir educando la autonomía a fn de tomar decisiones. Se analiza la importancia de contextualizar la enseñanza ética y la forma como esto se ha hecho en el curso. Finalmente se aborda la relevancia de formar la conciencia ética de los estudiantes.Palabras clave: Experiencia de enseñanza – Ética profesional –Método de discernimient.ResumoO artigo analisa o curso de Ética Profssional na Escola de Direito na Universidade Católica de Temuco. Examina a forma de como abordar a ética profssional antes da criação do curso, e o que tem acontecido com ele através de sucessivas mudanças curriculares e a introdução do modelo de competências. O curso aporta ao selo de identidade, através de uma abordagem multidisciplinar. O curso tem ligado teoria e prática, desde que começou a se programar até chegar atualmente a compreendê-lo na lógica de competência. Este olhar implica formar aos estudantes para resolver dilemas éticos, o que é feito pela metodologia do ver-julgar-agir. Este método de discernimento é próprio da tradição Católica, mas é usado neste contexto, sem um aspecto religioso. O método em questão permite ir educando na autonomia com a fnalidade de tomar decisões. Analisa-se a importância de contextualizar o ensino da ética e a forma como isso tem sido feito no curso. Finalmente se aborda a relevância de formar consciência ética dos estudantes.Palavras-chave: Experiência de ensino - Ética Profssional - Método de discernimento.AbstractThis paper analyses the Professional Ethics course at the School of Law of Universidad Católica de Temuco. It reviews the way in which ethics was addressed before the course was created, and what has happened with it through the subsequent curricular changes and the implementation of a competency based model. The course contributes to the seal of identity through a multidisciplinary approach. Theory and practice have been progressively bound together since the course was introduced, to reach a point, nowadays, in which the course is understood within the logic of competencies. This point of view implies educating students for solving ethical dilemmas, which is done through the see–judge–act methodology. This discernment methodology belongs to the Roman Catholic tradition, but is used in this context without its religious complexion. This method allows educating autonomy in order to make decisions. It also analyses the importance of contextualizing ethics education and the way in which this has been done in the course. Finally, it addresses the relevance ofcreating an ethical consciousness of the students.Keywords: Teaching experience – Professional Ethics – Discernment method


Physics ◽  
2021 ◽  
Vol 3 (2) ◽  
pp. 352-366
Author(s):  
Thomas Berry ◽  
Matt Visser

In this paper, Lorentz boosts and Wigner rotations are considered from a (complexified) quaternionic point of view. It is demonstrated that, for a suitably defined self-adjoint complex quaternionic 4-velocity, pure Lorentz boosts can be phrased in terms of the quaternion square root of the relative 4-velocity connecting the two inertial frames. Straightforward computations then lead to quite explicit and relatively simple algebraic formulae for the composition of 4-velocities and the Wigner angle. The Wigner rotation is subsequently related to the generic non-associativity of the composition of three 4-velocities, and a necessary and sufficient condition is developed for the associativity to hold. Finally, the authors relate the composition of 4-velocities to a specific implementation of the Baker–Campbell–Hausdorff theorem. As compared to ordinary 4×4 Lorentz transformations, the use of self-adjoint complexified quaternions leads, from a computational view, to storage savings and more rapid computations, and from a pedagogical view to to relatively simple and explicit formulae.


1980 ◽  
Vol 10 (4) ◽  
pp. 405-420 ◽  
Author(s):  
Olav Irgens-Jensen ◽  
Mons George Rud

In order to provide information on the way in which use of drugs - and of alcohol and tobacco -among young people changes over a period of time, the Norwegian National Institute for Alcohol Research has each spring, since 1968, conducted a survey of the youth of Oslo to determine their use of these drugs. The results are of significance not only from a scientific point of view but also from the point of view of practical policy-making. For instance, since 1974 there does not seem to have been any increase in alcohol consumption among the youth of Oslo, a fact which may reflect the measures which were introduced at that time in order to curb alcohol consumption among young people in Norway.


Author(s):  
Marcin Lefik ◽  
Krzysztof Komeza ◽  
Ewa Napieralska-Juszczak ◽  
Daniel Roger ◽  
Piotr Andrzej Napieralski

Purpose The purpose of this paper is to present a comparison between reluctance synchronous machine-enabling work at high internal temperature (HT° machine) with laminated and solid rotor. Design/methodology/approach To obtain heat sources for the thermal model, calculations of the electromagnetic field were made using the Opera 3D program including effect of rotation and the resulting eddy current losses. To analyse the thermal phenomenon, the 3D coupled thermal-fluid (CFD) model is used. Findings The presented results show clearly that laminated construction is much better from a point of view of efficiency and temperature. However, solid construction can be interesting for high speed machines due to their mechanical robustness. Research limitations/implications The main problem, despite the use of parallel calculations, is the long calculation time. Practical implications The obtained simulation and experimental results show the possibility of building a machine operating at a much higher ambient temperature than it was previously produced for example in the vicinity of the aircraft turbines. Originality/value The paper presents the application of fully three-dimensional coupled electromagnetic and thermal analysis of new machine constructions designed for elevated temperature.


Author(s):  
Abby S. Waysdorf

What is remix today? No longer a controversy, no longer a buzzword, remix is both everywhere and nowhere in contemporary media. This article examines this situation, looking at what remix now means when it is, for the most part, just an accepted part of the media landscape. I argue that remix should be looked at from an ethnographic point of view, focused on how and why remixes are used. To that end, this article identifies three ways of conceptualizing remix, based on intention rather than content: the aesthetic, communicative, and conceptual forms. It explores the history of (talking about) remix, looking at the tension between seeing remix as a form of art and remix as a mode of ‘talking back’ to the media, and how those tensions can be resolved in looking at the different ways remix originated. Finally, it addresses what ubiquitous remix might mean for the way we think about archival material, and the challenges this brings for archives themselves. In this way, this article updates the study of remix for a time when remix is everywhere.


2018 ◽  
Vol 42 (3) ◽  
pp. 344-366 ◽  
Author(s):  
Juan José Bustamante ◽  
Eric Gamino

This article examines the use of a presumption of illegality by local police officers to enforce a deportation regime in the Northwest Arkansas region. We employed an integrated racialized legal violence model to understand the way officers and immigration authorities collaborate to screen immigrants’ legal status for deportation purposes. Rather than focusing on how collaborations operate from an institutional point of view, the article provided a detailed and rich experiential description of participants’ realities shaped by the interplay of migration policy and local police practices. We concluded that the screening tactics used by local police in the cases considered in this article reflect a form of racialized legal violence intended to enforce a deportation regime against unauthorized people of Latino origin from this Arkansas area.


1987 ◽  
Vol 13 (1) ◽  
Author(s):  
L. P. Pretorius ◽  
C. J. H. Blignaut

From a perceptual point of view it is not clear whether, and under what conditions, the presence of colour in television commercials aids the processing of information. In this study it was argued that the way in which colour is used, would have an effect on the comprehension and memory of children regarding television commercials. It was found that colour, when used in a "concrete" fashion, aids the comprehension process. The results of the study also show that the "concrete" as well as the "symbolic" use of colour have a positive effect on the memory of children for the content of television commercials. Opsomming Vanuit 'n perseptuele benadering is dit nie duidelik of, en onder watter omstandighede, die teenwoordigheid van kleur in televisie advertensies die prosessering van inligting positief bei'nvloed nie. In hierdie studie is daar van die standpunt uitgegaan dat die wyse van kleurgebruik 'n effek sal he op die begrip en geheue van kinders ten aansien van televisie advertensies. Daar is gevind dat kleur, wat op 'n "konkrete" manier gebruik word, die begripsproses bevorder. Die resultate van die studie toon ook dat sowel die "konkrete" as "simboliese" gebruik van kleur 'n positiewe effek op die geheue van kinders ten opsigte van televisie advertensie inhoud het.


2002 ◽  
Vol 80 (1) ◽  
pp. 99-118 ◽  
Author(s):  
Margaret Olin

IN CAMERA LUCIDA, ROLAND BARTHES'S subject is the significance of photography's defining characteristic: the photograph's inseparable relation to its subject, that which ''must have been'' in front of the camera's lens. Or so it would seem. The present reading of Camera Lucida argues that Barthes's essay actually shows photography's nature as dependent not only on the intimate relation to its object, commonly termed ''indexical,'' but in accord with its relation to its user, its beholder. An examination of Barthes's encounters with photographs in Camera Lucida reveals the way in which identification and misidentification figure into the viewing of images, and suggests that contact between the beholder and the photograph actually eclipses the relation between the photograph and its subject. Barthes's focus on the emotional response of the viewer disguises the fact that he misidentified key details in Camera Lucida's photographs, most significantly in a 1927 portrait by James Van Der Zee and in the ''Winter Garden Photograph.'' This latter photograph of Barthes's recently deceased mother as a small child is famously not illustrated in the book. This essay argues that it is fictional. These ''mistakes'' suggest that Camera Lucida undermines its ostensible basis in indexicality. The subject did not have to be in front of the camera after all. The present rereading of the text from this point of view articulates a notion of performativity according to which the nature of the contact that exists between the image and the viewer informs the way an image is understood. Barthes's desire to find his mother again through her photograph to a large extent acts out his desire to re(per)form and make permanent his relation to her, a desire that he elucidates in the process of describing his search for her picture and his reaction to it when he finds it. This performative element is charged with identification; the person the narrator (Barthes) seeks, in his mother, is himself. A close analysis of the ''Winter Garden Photograph,'' as described by Barthes, shows how performances of identification are inscribed with gender and familial configurations.


2008 ◽  
Vol 37 (2) ◽  
Author(s):  
Iris Yaron

AbstractModern poetry developed and transformed difficulty into a prominent aesthetic norm of poetry. The abundance of difficult poetic texts necessitates a study of the corpus. After differentiating between the way difficulty is perceived in poetry and in other communicative acts, I present the approach that I have adopted for the purpose of studying difficult poetry. In contrast to other studies which have examined difficulty from the author's perspective and, as a consequence, described factors that cause textual difficulty, I propose to examine the subject from the reader's point of view. The reader, after all, is the one who feels or does not feel the difficulty. The concept ‘difficult poem’ is necessarily interdisciplinary and the question of what is “difficult” involves cognitive psychology and its models of text comprehension. Following a discussion of these domains, I present the “definition” that I propose for the ‘difficult poem’.


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