749 research outputs found
Anyone Can be a Fisherman in May
No full text(Statement of Responsibility) by Gabriel Esteban Rodriguez(Thesis) Thesis (B.A.) -- New College of Florida, 2010(Electronic Access) RESTRICTED TO NCF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE(Bibliography) Includes bibliographical references.(Source of Description) This bibliographic record is available under the Creative Commons CC0 public domain dedication. The New College of Florida, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.(Local) Faculty Sponsor: Coe, Richar
Proton double irradiation field-cycling nuclear magnetic resonance imaging: Testing new concepts and calibration methods
No full textDouble resonance experiments in field-cycling nuclear magnetic resonance (NMR) are powerful tools for the indirect detection of quadrupolar and electron resonances, dynamic nuclear polarization-induced signal amplification, within other possibilities. In the context of magnetic resonance imaging, double irradiation at high and low magnetic fields in field-cycling experiments can be conveniently used for instrumental calibration purposes and contrast manipulation. The basic goal of this article is to present a practical method for the measurement and calibration of the magnetic field in field-cycling magnetic resonance imaging instruments using proton resonances at high and low fields. We discuss an experimental protocol to adjust the optimal position of the gradient unit respect to the sample and the magnet system, and to measure the effective magnetic field gradient across the sample. A new modality of slice selection by irradiating the sample in the presence of a gradient field at low magnet-field conditions is also discussed. As a practical matter, we show how the sample irradiation at low fields can be used for contrast-enhancement, while handling the NMR signal intensity with spatial selectivity. To the best of our knowledge, this is the first calibration and adjustment package for a field-cycled magnetic resonance imaging instrument and the first example of double irradiation direct manipulation of contrasts in a proton image.Fil: Rodriguez, Gonzalo Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; Argentina. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; ArgentinaFil: Anoardo, Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; Argentina. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentin
A new social physic: The sociology of Gabriel Tarde and its legacy
No full textThis article aims to present a reconstruction of Gabriel Tarde’s micro-sociology in order to highlight its current relevance. The author of the article attempts to show that its distinction lies in taking the immense diversity of small social interactions as a starting point for the analysis of both face-to-face situations and large-scale institutions and social processes. Here the social field is described as made up of multiple propagations of desires and beliefs that spread from one individual to other, taking countless directions, interfering with each other, forming networks, and escaping them in search of new connections. The author attempts to show, also, that this point of view doesn’t deny the existence of social systems but understands them as open ensembles of immanent and partial relationships of collective beliefs and desires. This is why Tarde may be considered the founder of a molecular or micro-physical sociology.Fil: Tonkonoff, Sergio Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
Fast iron oxide-induced low-field magnetic resonance imaging
No full textDynamic images acquired by proton fast field-cycling magnetic resonance imaging are presented for the first time. Image contrast mediated by superparamagnetic iron oxide nanoparticles and weighted by the spin-lattice (T1) relaxation time, and both spin-lattice and spin-spin (T2) relaxation times, are discussed. Image acquisition and processing within 8 s is allowed for real-time recording of exemplary physical situations evolving in a compatible time-scale. Two simple examples are shown with the corresponding videos assembled by sequencing the acquired images. Fast iron oxide-induced low-field magnetic resonance imaging (MRI) constitutes the first step in the development of field-cycling functional MRI for biomedical and physical applications.Fil: Rodriguez, Gonzalo Gabriel. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomia y Física. Sección Física. Grupo de Resonancia Magnética Nuclear; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; ArgentinaFil: Erro, Eustaquio Martín. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomia y Física. Sección Física. Grupo de Resonancia Magnética Nuclear; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; ArgentinaFil: Anoardo, Esteban. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomia y Física. Sección Física. Grupo de Resonancia Magnética Nuclear; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; Argentin
Low-field MRI at high magnetic field instability and inhomogeneity conditions
No full textUnderstanding the effects of the magnetic field time instabilities in magnetic resonance imaging (MRI) is fundamental for the success of portable and low-cost MRI hardware based on electromagnets. In this work we propose a magnetic field model that considers the field instability in addition to the inhomogeneity. We have successfully validated the model on signals acquired with a commercial NMR instrument. It was used to simulate the image defects due to different types of instability for both the spin-echo and the gradient-echo sequences. We have considered both random field fluctuations, and an instability having a dominant harmonic component. Strategies are suggested to minimize the artifacts generated by these instabilities. Images were acquired using a home-made MRI relaxometer to show the consistency of the analysis.Fil: Rodriguez, Gonzalo Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; ArgentinaFil: Schürrer, Clemar A.. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; ArgentinaFil: Anoardo, Esteban. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; Argentin
Using Proton Nuclear Magnetic Resonance (NMR) as a calibrating reference for magnetic field measurement instruments: Sensitive volume and magnetic field homogeneity
No full textNuclear magnetic resonance can be conveniently used to set up reference values of magnetic flux densities for the calibration of measurement instrumentation. Two measurement procedures are proposed based on the Fourier analysis of the nuclear magnetic signal. Particularly, we consider the situation where the reference magnetic flux density may change its value across the sensor active area/volume due to spatial inhomogeneities. An explored potential solution uses an electronic compensation system in order to minimize the spatial inhomogeneities of the magnetic flux density within the calibrating volume. For this purpose, a previously designed device was added to the magnetic resonance apparatus. Both methods allow a performance better than 10 ppm in calibrating measurements by using a magnetic flux density source of the order of 100 ppm in spatial homogeneity within the calibrating volume. Examples of both methods are discussed.Fil: Rodriguez, Gonzalo Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; Argentina. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; ArgentinaFil: Forte, Guillermo Omar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; Argentina. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina. Trovintek Advanced Magnetic Systems; ArgentinaFil: Anoardo, Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; Argentina. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina. Trovintek Advanced Magnetic Systems; Argentin
Fidel and Gabo. A portrait of the legendary friendship between Fidel Castro and Gabriel García Márquez
No full textFew contemporary writers are more revered by Americans than Gabriel Garcia Marquez, the Nobel prize-winning author of Love in the Time of Cholera and One Hundred Years of Solitude. And few political leaders are more reviled than Fidel Castro. Yet these two seemingly disparate men are close friends. What could possibly unite these two men in friendship? In Fidel and Gabo, Marquez scholars Angel Esteban and Stephanie Panichelli examine this strange, intimate, and incredibly controversial friendship between the beloved author and Cuban dictator, exposing facets of their personalities never before revealed to the greater public. For years, Marquez, long fascinated with power, solicited and flattered Castro in hopes of a personal audience, for he viewed Castro's Cuba as the model on which Latin American would one day build its own brand of socialism. Upon their first meeting, Castro quickly came to regard Marquez as a genius and still calls him his closest friend and confidant. To this day, Marquez still gives Castro "first look" at all his manuscripts and craves his approval. Fidel and Gabo is a vivid and in-depth look at two of the most influential men of the modern era, their worlds, and the effect this friendship has had on their life and works
Conversaciones a cerca de las particularidades de la historia natural
No full textFecha probable de imp. tomada de la fe de erratas, 1753En frontis grab. calc.: "Is. a Peña sculp. Mti." y las [12] h. de grab. calc. pleg. de: "Joseph Andrade St., Peña scpt., Manl. Rodriguez sculps., Chozas sculp., Bus. á Scrivano sculp., Julian sculp.".El ej. A-003-453 (1), encuadernado por error tras la parte II del tomo IEnc. HolandesaSign.: [ ]1, ¶-¶¶¶¶4, ¶¶¶¶¶3, A-Z4, Aa-Mm
Conversaciones a cerca de las particularidades de la historia natural
No full textFecha de imp. tomada de la fe de erratasLa h. de grab. calc.: "Victe. Galcerán Scpt. Mti. 1752"Las h. de grab. calc.: "Mal. Rodriguez sculps.", "Vcte. Galcexan sculpt. Mti. 1752", "Gonzz. sculpt.", "Bus. a Eso S.", "Manul. de Chozas sculp."Enc. HolandesaSign.: [ ]2, A-Z4, Aa-Nn4, Oo
A fast field-cycling MRI relaxometer for physical contrasts design and pre-clinical studies in small animals
No full textWe present a fast field-cycling NMR relaxometer with added magnetic resonance imaging capabilities. The instrument operates at a maximum proton Larmor frequency of 5 MHz for a sample volume of 35 mL. The magnetic field homogeneity across the sample is 1400 ppm. The main field is generated with a notch-coil electromagnet of own design, fed with a current whose stability is 220 ppm. We show that images of reasonable quality can still be produced under such conditions. The machine is being designed for concept testing of the involved instrumentation and specific contrast agents aimed for field-cycling magnetic resonance imaging applications. The general performance of the prototype was tested through localized relaxometry experiments, T1-dispersion weighted images, temperature maps and T1-weighted images at different magnetic field intensities. We introduce the concept of positive and negative contrast depending on the use of pre-polarized or non-polarized sequences. The system is being improved for pre-clinical studies in small animals.Fil: Romero, Javier Agustin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; Argentina. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina. Universidad Nacional de Córdoba; Grupo de Resonancia Magnética Nuclear; Laboratorio de Relaxometría y Técnicas Especiales (LaRTE); ArgentinaFil: Rodriguez, Gonzalo Gabriel. Universidad Nacional de Córdoba; Grupo de Resonancia Magnética Nuclear; Laboratorio de Relaxometría y Técnicas Especiales (LaRTE); Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; Argentina. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; ArgentinaFil: Anoardo, Esteban. Universidad Nacional de Córdoba; Grupo de Resonancia Magnética Nuclear; Laboratorio de Relaxometría y Técnicas Especiales (LaRTE); Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; Argentina. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentin
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