Distressed geometry

An exhibition that examines the legacy and future of Constructivist and Geometric art

Qualitative tools & experimental philosophy

Experimental philosophy brings empirical methods to philosophy. These methods are used to probe how people think about philosophically interesting things such as knowledge, morality, freedom, etc. This paper explores the contribution that qualitative methods have to make in this enterprise. I argue that qualitative methods have the potential to make a much greater contribution than they have so far. Along the way, I acknowledge a few types of resistance that proponents of qualitative methods in experimental philosophy might encounter, and provide reasons to think they are ill-founded.

Experimental philosophy of language

Experimental philosophy of language uses experimental methods developed in the cognitive sciences to investigate topics of interest to philosophers of language. This article describes the methodological background for the development of experimental approaches to topics in philosophy of language, distinguishes negative and positive projects in experimental philosophy of language, and evaluates experimental work on the reference of proper names and natural kind terms. The reliability of expert judgments vs. the judgments of ordinary speakers, the role that ambiguity plays in influencing responses to experiments, and the reliability of meta-linguistic judgments are also assessed.

SIMULATIONS OF WINDS OF WEAK-LINED T TAURI STARS: THE MAGNETIC FIELD GEOMETRY AND THE INFLUENCE OF THE WIND ON GIANT PLANET MIGRATION

By means of numerical simulations, we investigate magnetized stellar winds of pre-main-sequence stars. In particular, we analyze under which circumstances these stars will present elongated magnetic features (e.g., helmet streamers, slingshot prominences, etc). We focus on weak-lined T Tauri stars, as the presence of the tenuous accretion disk is not expected to have strong influence on the structure of the stellar wind. We show that the plasma-beta parameter (the ratio of thermal to magnetic energy densities) is a decisive factor in defining the magnetic configuration of the stellar wind. Using initial parameters within the observed range for these stars, we show that the coronal magnetic field configuration can vary between a dipole-like configuration and a configuration with strong collimated polar lines and closed streamers at the equator (multicomponent configuration for the magnetic field). We show that elongated magnetic features will only be present if the plasma-beta parameter at the coronal base is beta(0) << 1. Using our self-consistent three-dimensional magnetohydrodynamics model, we estimate for these stellar winds the timescale of planet migration due to drag forces exerted by the stellar wind on a hot-Jupiter. In contrast to the findings of Lovelace et al., who estimated such timescales using the Weber and Davis model, our model suggests that the stellar wind of these multicomponent coronae are not expected to have significant influence on hot-Jupiters migration. Further simulations are necessary to investigate this result under more intense surface magnetic field strengths (similar to 2-3 kG) and higher coronal base densities, as well as in a tilted stellar magnetosphere.

Shot Noise in a Spin-Diode Geometry

We apply the master equation technique to calculate shot noise in a system composed of single level quantum dot attached to a normal metal lead and to a ferromagnetic lead (NM-QD-FM). It is known that this system operates as a spin-diode, giving unpolarized currents for forward bias and polarized current for reverse bias. This effect is observed when only one electron can tunnel at a time through the dot, due to the strong intradot Coulomb interaction. We find that the shot noise also presents a signature of this spin-diode effect, with a super-Poissonian shot noise for forward and a sub-Poissonian shot noise for reverse bias voltages. The shot noise thus can provide further experimental evidence of the spin-rectification in the NM-QD-FM geometry.

Why Implementing History and Philosophy in School Science Education is a Challenge: An Analysis of Obstacles

Teaching and learning with history and philosophy of science (HPS) has been, and continues to be, supported by science educators. While science education standards documents in many countries also stress the importance of teaching and learning with HPS, the approach still suffers from ineffective implementation in school science teaching. In order to better understand this problem, an analysis of the obstacles of implementing HPS into classrooms was undertaken. The obstacles taken into account were structured in four groups: 1. culture of teaching physics, 2. teachers` skills, epistemological and didactical attitudes and beliefs, 3. institutional framework of science teaching, and 4. textbooks as fundamental didactical support. Implications for more effective implementation of HPS are presented, taking the social nature of educational systems into account.

An algorithm for automatic checking of exercises in a dynamic geometry system: iGeom

One of the key issues in e-learning environments is the possibility of creating and evaluating exercises. However, the lack of tools supporting the authoring and automatic checking of exercises for specifics topics (e.g., geometry) drastically reduces advantages in the use of e-learning environments on a larger scale, as usually happens in Brazil. This paper describes an algorithm, and a tool based on it, designed for the authoring and automatic checking of geometry exercises. The algorithm dynamically compares the distances between the geometric objects of the student`s solution and the template`s solution, provided by the author of the exercise. Each solution is a geometric construction which is considered a function receiving geometric objects (input) and returning other geometric objects (output). Thus, for a given problem, if we know one function (construction) that solves the problem, we can compare it to any other function to check whether they are equivalent or not. Two functions are equivalent if, and only if, they have the same output when the same input is applied. If the student`s solution is equivalent to the template`s solution, then we consider the student`s solution as a correct solution. Our software utility provides both authoring and checking tools to work directly on the Internet, together with learning management systems. These tools are implemented using the dynamic geometry software, iGeom, which has been used in a geometry course since 2004 and has a successful track record in the classroom. Empowered with these new features, iGeom simplifies teachers` tasks, solves non-trivial problems in student solutions and helps to increase student motivation by providing feedback in real time. (c) 2008 Elsevier Ltd. All rights reserved.

Decay of geometry for Fibonacci critical covering maps of the circle

We study the growth of Df `` (f(c)) when f is a Fibonacci critical covering map of the circle with negative Schwarzian derivative, degree d >= 2 and critical point c of order l > 1. As an application we prove that f exhibits exponential decay of geometry if and only if l <= 2, and in this case it has an absolutely continuous invariant probability measure, although not satisfying the so-called Collet-Eckmann condition. (C) 2009 Elsevier Masson SAS. All rights reserved.

Periodic geodesics and geometry of compact Lorentzian manifolds with a Killing vector field

We study the geometry and the periodic geodesics of a compact Lorentzian manifold that has a Killing vector field which is timelike somewhere. Using a compactness argument for subgroups of the isometry group, we prove the existence of one timelike non self-intersecting periodic geodesic. If the Killing vector field is nowhere vanishing, then there are at least two distinct periodic geodesics; as a special case, compact stationary manifolds have at least two periodic timelike geodesics. We also discuss some properties of the topology of such manifolds. In particular, we show that a compact manifold M admits a Lorentzian metric with a nowhere vanishing Killing vector field which is timelike somewhere if and only if M admits a smooth circle action without fixed points.

COMPARISON RESULTS FOR CONJUGATE AND FOCAL POINTS IN SEMI-RIEMANNIAN GEOMETRY VIA MASLOV INDEX

We prove an estimate on the difference of Maslov indices relative to the choice of two distinct reference Lagrangians of a continuous path in the Lagrangian Grassmannian of a symplectic space. We discuss some applications to the study of conjugate and focal points along a geodesic in a semi-Riemannian manifold.

Understanding the Effect of Adsorption Geometry over Substrate Selectivity in the Surface-Enhanced Raman Scattering Spectra of Simazine and Atrazine

This paper studies the selectivity of Well-defined Au and Ag nanostructures as substrates for the SERS, (surface-enhanced Raman scattering) detection of simazine (6-chloro-N,N`-diethyl-1,3,5-triazine-2,4-diamine) and atrazine (6-chloro-N-ethyl-N`-isopropyl-1,3,5-triazine-2,4-diamine). Our data showed that simazine and atrazine displayed similar SERS spectra when the Au was employed as substrate. Conversely, distinct SERS signatures were obtained upon the utilization of Ag substrates. Density functional theory (DFT) calculations and vibrational assignments suggested that, while simazine and atrazine adsorbed on Au via the N3 position of the triazine ring, simazine adsorbed on Ag via N3 and atrazine via N5. The results presented herein demonstrated that the adsorption geometry of analyte molecules can play a central role over substrate selectivity in SERS, which is particularly important in applications involving ultrasensitive analysis of mixtures containing structurally similar molecules.

Dissonant Voices : Philosophy, Children's Literature, and Perfectionist Education

Dissonant Voices has a twofold aspiration. First, it is a philosophical treatment of everyday pedagogical interactions between children and their elders, between teachers and pupils. More specifically it is an exploration of the possibilities to go on with dissonant voices that interrupt established practices – our attunement – in behaviour, practice and thinking. Voices that are incomprehensible or expressions that are unacceptable, morally or otherwise. The text works on a tension between two inclinations: an inclination to wave off, discourage, or change an expression that is unacceptable or unintelligible; and an inclination to be tolerant and accept the dissonant expression as doing something worthwhile, but different. The second aspiration is a philosophical engagement with children’s literature. Reading children’s literature becomes a form of philosophising, a way to explore the complexity of a range of philosophical issues. This turn to literature marks a dissatisfaction with what philosophy can accomplish through argumentation and what philosophy can do with a particular and limited set of concepts for a subject, such as ethics. It is a way to go beyond philosophising as the founding of theories that justify particular responses. The philosophy of dissonance and children’s literature becomes a way to destabilise justifications of our established practices and ways of interacting. The philosophical investigations of dissonance are meant to make manifest the possibilities and risks of engaging in interactions beyond established agreement or attunements. Thinking of the dissonant voice as an expression beyond established practices calls for improvisation. Such improvisations become a perfectionist education where both the child and the elder, the teacher and the student, search for as yet unattained forms of interaction and take responsibility for every word and action of the interaction. The investigation goes through a number of picture books and novels for children such as Harry Potter, Garmann’s Summer, and books by Shaun Tan, Astrid Lindgren and Dr. Seuss as well narratives by J.R.R. Tolkien, Henrik Ibsen, Jane Austen and Henry David Thoreau. These works of fiction are read in conversation with philosophical works of, and inspired by, Ludwig Wittgenstein and Stanley Cavell, their moral perfectionism and ordinary language philosophy.

Perfectionist Philosophy as a (an Untaken) Way of Life

I am honored to respond to Paul Guyer’s elaboration on the role of examples of perfectionism in Cavell’s and Kant’s philosophies. Guyer’s appeal to Kant’s notion of freedom opens the way for suggestive readings of Cavell’s work on moral perfectionism but also, as I will show, for controversy. There are salient aspects of both Kant’s and Cavell’s philosophy that are crucial to understanding perfectionism and, let me call it, perfectionist education, that I wish to emphasize in response to Guyer. In responding to Guyer’s text, I shall do three things. First, I shall explain why I think it is misleading to speak of Cavell’s view that moral perfectionism is involved in a struggle to make oneself intelligible to oneself and others in terms of necessary and sufficient conditions for moral perfection. Rather, I will suggest that the constant work on oneself that is at the core of Cavell’s moral perfectionism is a constant work for intelligibility. Second, I shall recall a feature of Cavell’s perfectionism that Guyer does not explicitly speak of: the idea that perfectionism is a theme, “outlook or dimension of thought embodied and developed in a set of texts.” Or, as Cavell goes on to say, “there is a place in mind where good books are in conversation. … [W]hat they often talk about … is how they can be, or sound, so much better than the people that compose them.” This involves what I would call a perfectionist conception of the history of philosophy and the kinds of texts we take to belong to such history. Third, I shall sketch out how the struggle for intelligibility and a perfectionist view of engagement with texts and philosophy can lead to a view of philosophy as a form of education in itself. In concluding these three “criticisms,” I reach a position that I think is quite close to Guyer’s, but with a slightly shifted emphasis on what it means to read Kant and Cavell from a perfectionist point of view.

'In Charge of the Truffula Seeds' : On Children's Literature, Rationality and Children's Voices in Philosophy

In this paper I investigate how philosophy can speak for children and how children can have a voice in philosophy and speak for philosophy. I argue that we should understand children as responsible rational individuals who are involved in their own philosophical inquiries and who can be involved in our own philosophical investigations-not because of their rational abilities, but because we acknowledge them as conversational partners, acknowledge their reasons as reasons, and speak for them as well as let them speak for us and our rational community. In order to argue this I turn, first, to Gareth Matthews' philosophy of childhood and suggest a reconstruction of some of his concepts in line with the philosophy of Stanley Cavell. Second, in order to examine more closely our conceptions of rationality and our pictures of children, I consider the children's books, The Lorax and Where is My Sister? and Henrik Ibsen's play, The Wild Duck.