1,583 research outputs found
Alan Litke, inventor of the device that records the neural activity of retinal cells
No full textAlan Litke is the inventor of a system that can record the neural activity of retinal cells. The system was inspired by the silicon microstrip detector technology employed in ATLAS
"Máster, ¿a qué hora termina el entrenamiento?"
No full textEn este capítulo reflexiono sobre el vínculo establecido con el grupo de futbolistas mujeres que son las interlocutoras de mi investigación. Indago en la forma en que, como antropólogo varón cis heterosexual, es posible construir conocimiento que sea considerado un aporte para las futbolistas feministas villeras, al mismo tiempo que muestro la forma en que ellas negocian mi posición como académico en el campo. Analizo las posibilidades de construcción de conocimiento en la relación con interlocutoras con las que comparto un proyecto político, a partir de la noción de reflexividad.Fil: Alvarez Litke, Martín. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Filosofía y Letras. Instituto Interdisciplinario de Estudios de Género; Argentin
Variational Methods in Surface Parameterization
No full textA surface parameterization is a function that maps coordinates in a 2-dimensional parameter space to points on a surface. This thesis investigates two kinds of parameterizations for surfaces that are disc-like in shape. The first is a map from a region of the plane to the surface. The second is a mapping from one surface to another, which defines a correspondence between them. The main challenge in both cases is the construction of a smooth map with low distortion. In this thesis we present a variational approach to surface parameterization that addresses these challenges.
The first contribution of this thesis is the development of a variational framework for parameterizations. This framework encompasses the mapping of a region of the plane to a surface that is isomorphic to a disc, and the mapping between such surfaces. It is based on the rich mathematical theory built up over decades in the study of rational mechanics. Because of its roots in mechanics, our parameterizations are guaranteed to be smooth and locally bijective, and optimal parameterizations which minimize a variational energy are known to exist. A proof of existence is given for the case of optimal parameterizations in the plane.
Our second contribution is a set of algorithms to construct parameterizations for surface triangulations. We describe in detail free-boundary methods that use standard numerical optimization algorithms for the computation of optimal parameterizations. A flexible set of parameters is offered to the user to formulate preferences for the trade-off between angle, area and length distortion in parameterizations in the plane. In the specification of a correspondence between surfaces, we provide user control through feature lines which are mapped as sets onto corresponding feature lines. Additionally we allow for a partial correspondence of the surfaces which is particularly important for correlating surfaces with boundaries.
Our third contribution is an analysis of the performance of the algorithms based on our implementations. Our testing focuses on parameterizations of physically-acquired triangle mesh data. The efficiency of our methods is measured by analyzing the rate of convergence of the energy minimization, and execution times are shown to be quite reasonable. Robustness is established in the presence of large deformations in the parameterizations and the stability of our parameterizations is demonstrated under different discretizations of the surfaces.
Our fourth contribution is a set of concrete, compelling applications of surface parameterization. Non-trivial examples which draw from texture mapping, morphing and facial animation provide further evidence and insight into the versatility of our parameterization framework.</p
Drawing the line: A Review of Research on Women's Football
No full textSi bien el género ha estado presente en los estudios sobre deporte en Argentina desde sus comienzos, aún son escasos los trabajos que analizan la participación de las mujeres en el deporte más importante del país: el fútbol. El presente artículo pretende ser una contribución en este aspecto, analizando la incipiente bibliografía local sobre el fútbol femenino, a la luz de la más amplia producción internacional sobre la temática, mostrando los principales hallazgos, silencios, y las preguntas que quedan pendientes. Recuperamos los aportes de las investigaciones en torno a la sexualidad y la corporalidad de las deportistas, atendiendo a las posibilidades de rearticulación del dispositivo sexo-género-deseo a partir de la práctica del fútbol, y proponemos la necesidad de realizar etnografías que atiendan a la construcción identitaria de las jugadoras y a los sentidos que adquiere su práctica.Although the subject of gender has been present in sports studies in Argentina from the start, there are still very few studies that analyze the participation of women in the most important sport in the country: football. This article aims to be a contribution in this aspect, analyzing the incipient local bibliography on women's football, in light of the more extended international production on the subject, showing the main findings, silences, and the questions that remain pending. We recover the contributions of research on the sexuality and corporality of the athletes, taking into account the possibilities of rearticulation of the sex-gender-desire order that derive from the practice of football, and propose the need to carry out ethnographic research on the identitary construction of the women players and the meanings their practice acquires.Fil: Alvarez Litke, Martín. CONICET/ Instituto Interdisciplinario de Estudios de Género. Universidad de Buenos Aires
Large-scale multielectrode recording and stimulation of neural activity
No full textLarge circuits of neurons are employed by the brain to encode and process information. How this encoding and processing is carried out is one of the central questions in neuroscience. Since individual neurons communicate with each other through electrical signals (action potentials), the recording of neural activity with arrays of extracellular electrodes is uniquely suited for the investigation of this question. Such recordings provide the combination of the best spatial (individual neurons) and temporal (individual action-potentials) resolutions compared to other large-scale imaging methods. Electrical stimulation of neural activity in turn has two very important applications: it enhances our understanding of neural circuits by allowing active interactions with them, and it is a basis for a large variety of neural prosthetic devices. Until recently, the state-of-the-art in neural activity recording systems consisted of several dozen electrodes with inter-electrode spacing ranging from tens to hundreds of microns. Using silicon microstrip detector expertise acquired in the field of high-energy physics, we created a unique neural activity readout and stimulation framework that consists of high-density electrode arrays, multi-channel custom-designed integrated circuits, a data acquisition system, and data-processing software. Using this framework we developed a number of neural readout and stimulation systems: (1) a 512-electrode system for recording the simultaneous activity of as many as hundreds of neurons, (2) a 61-electrode system for electrical stimulation and readout of neural activity in retinas and brain-tissue slices, and (3) a system with telemetry capabilities for recording neural activity in the intact brain of awake, naturally behaving animals. We will report on these systems, their various applications to the field of neurobiology, and novel scientific results obtained with some of them. We will also outline future directions
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The Interstellar Medium in Gravitationally Lensed Dusty Star-Forming Galaxies
No full textIn this dissertation, I characterize the interstellar medium (ISM) in two gravitationally lensed dusty star-forming galaxies (DSFGs) from the South Pole Telescope (SPT) survey using observations from the Atacama Large Millimeter/submillimeter Array (ALMA), the most intensely star-forming galaxy and the most distant galaxy from this sample.In Chapter 1, I provide context and background about galaxies, gravitational lensing, and the ISM.
In Chapter 2, I use high-resolution observations of [CII]158 and continuum dust emission to study SPT0346-52, a gravitationally lensed system at z=5.7.I use a pixelated, interferometric lens modeling code to ``de-lens'' the emission from SPT0346-52 and reconstruct its source-plane structure.
With these reconstructions, I study the ``[CII]-deficit'', an observed phenomenon where the [CII]58/L_FIR ratio falls as Sigma_FIR increases.
I then explore the kinematics of \cii 158 in SPT0346-52 in detail using position-velocity diagrams and the Toomre Q stability parameter.
This work was published in Litke, et al. (2019).
In Chapter 3, I follow up on SPT0346-52 with ALMA observations of [NII]205, [CII]158, [OI]146, [NII]122, [OI]63, and dust continuum in order to study the multi-phase ISM in this system.As in Chapter 2, I reconstruct the source-plane emission.
I use the photoionization code Cloudy to model the conditions of the ISM.
I explore deficits in all of the lines observed.
I study the neutral phase of the ISM, the electron density in the diffuse ionized phase, and I discuss the implications of the non-detection of [OI]63.
This work was published in Litke, et al. (2022).
In Chapter 4, I discuss on-going work using ALMA observations of [CII]158, [OI]146, [NII]122, [OIII]88, and dust continuum to study the multi-phase ISM in the z=6.9 interacting galaxies of SPT0311-58.I use different line and continuum ratios to determine the ionization parameter and metallicity, and constrain the density of the neutral gas phase.
In Chapter 5, I summarize the results of my work and the properties of these two systems, and discuss follow-up observations
The Retinal Readout System: a status report: A Status Report
No full textThe 'Retinal Readout System' is being developed to study the language the eye uses to send information about the visual world to the brain. Its architecture is based on that of silicon microstrip detectors. An array of 512 microscopic electrodes picks up the signals generated by the output neurons of live retinal tissue in response to a dynamic image focused on the input neurons. These signals are amplified, filtered and multiplexed by a set of eight custom-designed VLSI readout chips, and digitized and recorded by a data acquisition system. This report describes the goals, design, and status of the system. (author
Theorizing Fundamental Music/Dance Interactions in Salsa
No full textCommunication between music and dance can take many forms. In salsa, this communication begins with and builds upon two simple but crucial criteria: for music, a metric-rhythmic foundation based on clave and other essential performance strata, and for dance, the flow and metric orientation of one of three basic footwork patterns. Most of the rich complexity of music, dance, and their interaction stems from these fundamental gestures. In this article we analyze the basic structures of salsa music and dance, theorize how they interact, and investigate three scenarios where dancers have to make decisions about how to attend to musical features via their footwork orientations.No Full Tex
Agronomy Career Influence Survey
No full textA survey instrument to assess assess perceptions of women in agronomy careers.
The 2015 "Perceptions of women in agronomy careers" by Litke, Graham Ross (M.S., Tarleton State University, 2015, 28; ProQuest UMI Pub. No. 1589553; ISBN: 9781321773545) reports a dataset utilizing this instrument. Creation of this instrument was made possible in part by the United States Department of Agriculture (USDA) through the National Institute of Food and Agriculture (NIFA) grant 2012-38503-20278.Peer-review publication of data collected with this instrument is in submission
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