3,959 research outputs found
Design and Topological Characterization of 2D Photonic Crystals
111 p.En esta tesis se describe la metodología necesaria para caracterizar la topología de cristales fotónicos bidimensionales. Se muestran diferentes métodos basados en invariantes topológicas y en teoría de grupos, así como la importancia de la posición de las funciones de Wannier. La posición predicha porsimetría de estas funciones en la celda unidad del cristal son comparadas con la posición de los máximosde densidad local de estados. Además, se muestran ejemplos de cristales con diferente topología,detallando las principales diferencias entre ellos. Incluyendo la descripción teórica del primer diseño decristal fotónico con topología frágil
Gestión sustentable del recurso hídrico en Bahía Blanca
El sudoeste bonaerense enfrenta actualmente un crisis hídrica generada por sus características hidrográficas y régimen de precipitaciones, así como también por la insuficiente inversión realizada en la infraestructura necesaria para la prestación del servicio de agua corriente. Esta situación se agrava dada la ausencia de conciencia social por parte de la población en cuanto al uso del recurso.Área: Ciencias Sociales y Humanas
Évora Studies in the Philosophy and History of Science Volume Two From Ontology To Structure
The structuralist approaches retake the war, characteristic of ancient Greek thought, between the partisans of matter
and the ‘friends of ideas’, although they
abandon the metaphysical and ontological issues,
thus favouring the methodological aspects of
knowledge, focusing on those functions which
constitute and build up the worlds of human
culture. The present volume contains the results of the seventh Évora International Symposium in Philosophy and History of Science and Technology, entitled “Structuralism: Roots, Plurality, and
Contemporary debates” (2016)
Optimization of Myocardial First- Pass Perfusion MR Imaging using Gadolinium and Differences in FiO2
The correct perfusion of the myocardium, the heart’s muscle, is a key parameter that has been
proven to be a powerful tool for the diagnosis of cardiovascular diseases. In general, perfusion
is defined as the delivery of oxygen and nutrients by the circulatory system to any tissue or
organ. When an organ like the heart receives insufficient blood supply, an ischemic disease is
likely to take place.
So far, several image techniques have been used for the study of myocardial perfusion such as
CT, PET, SPECT or MRI. Due to its high spatial resolution and the avoidance of limitations offered
by ionizing radiation the following project specifically addresses the MRI technique. The use of
MRI as diagnostic readouts in patients suffering from cardiovascular diseases is currently
growing in the clinics. Therefore, having this protocol optimize in a research lab will be of great
interest
This work was carried out using a 7 Tesla MRI scanner. This scanner is made for preclinical
research with small animal models which is the first step performed in every research project
before it can be translated into humans. For the study of perfusion in MRI a contrast agent
(commonly gadolinium-based) must be intravenously administered to the patient. However, this
approach offers many drawbacks regarding secondary effects with gadolinium posing health risk
in patients.
In this context, this project investigates the possibility of avoiding such contrast agent by using
intrinsic blood oxygenation level instead. This idea relies on the Blood Oxygenated Level
Dependent (BOLD) principle that describes the magnetic characteristics of oxyhemoglobin and
deoxyhemoglobin. To this end, the first step was the implementation of a first-pass perfusion in
rat’s myocardium using gadolinium as contrast agent. The change produced by the passage of
the gadolinium bolus can be screen with T1 weighted images. A Graphic User Interface was
developed using MATLAB so as to easily asses the results and furtherly compared both contrast
agents.
The paramagnetic characteristics of deoxyhemoglobin locally alters the main magnetic field of
the MRI scanner if its concentration is increased. For this purpose, a gas mixer with two different
mixtures, one with 100% Oxygen and the other with 100% Nitrogen, was used so as to produce
changes in the fractions of inspired oxygen (FiO2). Therefore, this method studies the
relationship between the MRI signal created by the deoxyhemoglobin bolus and the changes of
FiO2 recorded by a pulse-oximeter.
After several MRI sequence adjustments, the scanner was capable of recording the signal
produced by the deoxyhemoglobin bolus. Even though the gadolinium signal is more precise
and accurate, our new proposal is clearly a focal point for further research since it overcomes
health inconvenience offered by the contrasts in used.Ingeniería Biomédic
Guest editors’ introduction
Guest Editors’ introduction to the Monographic Section
Desarrollo de una taxonomía de las intervenciones farmacéuticas en pacientes VIH+ basados en el modelo CMO
Objective: To agree on a proposal for pharmaceutical interventions and establish their classification taxonomy according to the CMO-Pharmaceutical Care Model (Capacity-Motivation- Opportunity). Method: A study conducted between March and May, 2016. Two phases of development were defined. A literature review was initially conducted. Then, the DELPHI-Rand-UCLA methodology was used in order to reach a consensus about those interventions selected, and to define the taxonomy. Fifteen (15) experts, specialists in Pharmaceutical Care for HIV+ patients, were selected. This selection was explicitly conducted, following a protocol in order to avoid any bias. An initial proposal was developed according to the interventions extracted from Phase 1. These were tentatively classified according to the CMO Model, in a category based on their design and utility. Three issues were raised from the initial question: Do you agree with the proposed classification? If not, there was an option to re-categorize. Additionally, they were asked about the importance, priority and impact to achieve pharmacotherapeutic objectives that they would assign to it. Interventions were classified according to the degree of agreement. Once a consensus was reached, the final taxonomy was established. Results: Eighteen (18) articles were finally considered. The initial proposal included 20 pharmaceutical interventions with the following classification: seven in Capacity, eight in Motivation, and five in Opportunity. Those interventions considered to have greater importance and priority were: Review and Validation, Safety, and Adherence. The interventions with the greatest impact were: Review and Validation, Coordination, Adherence, and Motivation. On the other hand, the lowest scores for importance were for: Planning and Social Coordination; and in terms of impact: Social Coordination. Conclusions: The taxonomy reached by consensus will allow to classify pharmaceutical interventions with the new model, and therefore to conduct an improved research and patient care
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