Search results for "Mirror"
showing 10 items of 202 documents
Reversing arrows: Duality
2021
What do you get reversing all arrows? The drawing ‘Duality’ is an homage to mirrors, classical art themes, and abstract mathematics.I’m looking for beauty in the arts and beauty in science. It’s a ...
Temporal multiplexing with adaptive optics for simultaneous vision.
2016
We present and test a methodology for generating simultaneous vision with a deformable mirror that changed shape at 50 Hz between two vergences: 0 D (far vision) and −2.5 D (near vision). Different bifocal designs, including toric and combinations of spherical aberration, were simulated and assessed objectively. We found that typical corneal aberrations of a 60-year-old subject changes the shape of objective through-focus curves of a perfect bifocal lens. This methodology can be used to investigate subjective visual performance for different multifocal contact or intraocular lens designs.
Issues Related to the Restoration of Mirrors of the Wooden paliotto della chiesa del Santissimo Crocifisso all’Albergheria, Sicily (Italy)
2017
ABSTRACTIn this work, the decision-making process involved in the restoration of the eighteenth century paliotto ligneo (wooden altar frontal) della chiesa del Santissimo Crocifisso all’Albergheria of Palermo is presented. Earlier research concerning mirror restoration was based on only a few case studies and the proposed techniques were not suitable for the artwork here. As a consequence, it was necessary to re-examine theories and protocols of modern restoration to plan an appropriate intervention of the altar frontal. Since in this artwork the role of mirrors is not to give back images, as usual, but rather to create special light effects and play of lights, this work aims to find an app…
Modulation of cortical motor outputs by the symbolic meaning of visual stimuli
2010
The observation of an action modulates motor cortical outputs in specific ways, in part through mediation of the mirror neuron system. Sometimes we infer a meaning to an observed action based on integration of the actual percept with memories. Here, we conducted a series of experiments in healthy adults to investigate whether such inferred meanings can also modulate motor cortical outputs in specific ways. We show that brief observation of a neutral stimulus mimicking a hand does not significantly modulate motor cortical excitability (Study 1) although, after prolonged exposure, it can lead to a relatively nonspecific modulation (Study 2). However, when such a neutral stimulus is preceded b…
Does the brain know who is at the origin of what in an imitative interaction?
2012
International audience; Brain correlates of the sense of agency have recently received increased attention. However, the explorations remain largely restricted to the study of brains in isolation. The prototypical paradigm used so far consists of manipulating visual perception of own action while asking the subject to draw a distinction between self- versus externally caused action. However, the recent definition of agency as a multifactorial phenomenon combining bottom-up and top-down processes suggests the exploration of more complex situations. Notably there is a need of accounting for the dynamics of agency in a two-body context where we often experience the double faceted question of w…
Real-time acquisition of complex optical fields by binary amplitude modulation
2017
We describe, through simulations and experiments, a real-time wavefront acquisition technique using random binary amplitude masks and an iterative phase retrieval algorithm based on the Fresnel propagator. By using a digital micromirror device, it is possible to recover an unknown complex object by illuminating with this set of masks and simultaneously recording the resulting intensity patterns with a high-speed camera, making this technique suitable for dynamic applications.
Drifts in real-time partial wavefront correction and how to avoid them
2017
In visual experiments that require real-time partial correction of wavefront aberrations, small errors occur that accumulate over time and lead to drifts in Zernike coefficients of the uncorrected aberrations. A simple algorithm that does not require the inclusion of an additional optical path to obtain independent measurements of the eye's aberrations is described here, and its effectiveness in preventing these drifts is demonstrated.
Astronomical soft x-ray mirrors reflectivity enhancement by multilayer coatings with carbon overcoating
2004
A number of X-ray astronomical missions of near future will make use of hard X-ray optics with broad-band multilayer coatings. However multilayer mirrors can be also useful to enhance the effective area of a given X-ray telescope in the "classical" low energy X-ray band (0.1 – 10 keV), the window where X-ray spectroscopy provides very useful plasma diagnostics) with a consistent gain with respect to usual single-layer reflectors. Multilayers for soft X-rays are based on stacks with constant d-spacing (in order to minimize the loss due to the photoelectric effect). A further gain in reflectivity (however only restricted to the energy range between 0.5 and 4 keV) can be achieved by using a lo…
Combination of simple mirrors – childish game or useful tool?
2015
International audience; The Scottish inventor of the kaleidoscope, Sir David Brewster (1781-1868), examined references to previous combinations of mirrors in his defense of his own invention, The Kaleidoscope, Its History, Theory and Construction (1858). Sir David Brewster who was eager to prove that his invention, dating back to 1816, was genuinely innovative, dismissed the use of what he called “combinations of plane mirrors” as productive of “poor effect”. His examination of the mirror devices described in the works of Gianbattista della Porta (1535-1615) Athanasius Kircher (1601-1680) and Richard Bradley (1688-1732), led him to the conclusion that they could hardly have been the result …
L'iconicité phonologique dans les neurosciences cognitives et dans la tradition linguistique française
2014
A significant part of the recent research in language neuropsychology and neurophysiology seems to revive the long-standing hypothesis of an originally motivated relations hip between phonetics and semantics. Even if phonological iconicity is a long neglected subject in linguistics, particularly in French linguistics of the second half of the XXth century, a long tradition of researches does exist. It can be traced back to Plato in the old age and to Leibniz in modern age, and it has important manifestations in France too. This article aims to illustrate critically the theories of phonological iconicity developed by Charles de Brosses at the age of Enlightenment (1765), by Maurice Grammont …