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Mishin, A. "Biomagnetic signal analysis." Thesis, Swansea University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.638202.
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Most of this thesis is an account of the effort to develop new methods for biomagnetic data analysis. Variations of the heart rate reflect the neural heart control mechanisms which are performed via the electrical modulation of the sinoatrial node by the autonomic nervous system. This modulation involves the interaction of several physiological mechanisms that operate on differing time scales. Using SQUID (superconducting quantum interference device) instrumentation, the fetal cardiogram can be measured with great accuracy and a high temporal resolution, thereby providing the opportunity to assess the neural function in the fetus non-invasively by analysing heart rate variability (HRV). However, a quantitative analysis of HRV requires several other physiological parameters such as blood pressure, respiration etc. to be analysed simultaneously with HRV. These parameters are obviously inaccessible in the fetus although they are routinely recorded in premature neonates treated in the intensive care units. Using a time domain correlation method, the behaviour of different HRV components was quantitatively studied for both fetuses and premature neonates and a number of consistent features were found. The correlation between neonatal HRV, respiration and arterial blood pressure was studied with the ultimate goal of constructing a numerical model of HRV. It was also observed that different types of ventilation equipment used in neonatal intensive care cause different patterns of respiration/HRV correlation, which may be indicative of the efficacy of the ventilator. Investigation of the spontaneous activity of the human brain and in particular alpha rhythm is another area where SQUID-based biomagnetic techniques can make an important contribution. In the final chapter of this work the multichannel alpha magnetoencephalogram (MEG) is considered as a sequences of MEG maps. A neural-net based algorithm for segmentation of MEG records into words is presented. Using this method three recurring words were found in an eight-second magnetoecephalogram. This could be of value for active testing of the functional role of the cortex in neurological experiments.
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Chopin, Chloé. "Biomagnetic sensors based on spin electronics." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASP022.
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L’effet de magnétorésistance géante (GMR) permet de fabriquer des capteurs magnétiques avec une bonne sensibilité dont la résistance est proportionnelle au champ magnétique. De plus, ils sont sensibles à petite taille (quelques microns), à température ambiante et selon une direction de sensibilité unique. Ce sont donc des capteurs intéressants pour mesurer les champs magnétiques générés par l’activité électrique des neurones à l’échelle locale, comme les potentiels d’action, dont l’amplitude est attendue entre 10 et 100 pT à 1 kHz. Comme les capteurs GMR ont une limite de détection (LOD) de l‘ordre du nT à basse fréquence, plusieurs études ont été menées, notamment sur la taille et la composition du capteur GMR pour l’améliorer. La sonde qui implémente ces capteurs pour les mesures in-vivo, appelée magnétrode, a également été optimisée selon deux axes particuliers : sa pointe est affinée pour en limiter l’invasivité d’une part et intègre plusieurs capteurs GMR qui peuvent notamment réaliser des mesures en 2D d’autre part. Ces magnétrodes ont ainsi été appliquées à la mesure in-vivo sur des rongeurs. Les sondes ainsi développées et optimisées conservent une LOD de 1 nT autour de 1 kHz et ont gagné en stabilité ce qui a permis de réduire le niveau de bruit pendant les expériences in-vivo en moyennant sur un nombre important d’évènements. De plus, une magnétrode permettant de mesurer un champ magnétique en 2D a été développée. Enfin, les capteurs GMR sont à l’état de l’art sur une magnétrode dont la pointe a été affinée pour une épaisseur finale de 25 µm. Les sondes réalisées permettent de mesurer in-vivo des signaux magnétiques d’une amplitude de l’ordre de 250 pTMagnetic sensors based on the Giant Magnetoresistance (GMR) effect have a good sensitivity with a resistance which is proportional to the external magnetic field. In addition, they are sensitive at small scale (a few microns), at room temperature and along a unique axis of sensitivity. Thus, they are good candidates to measure the magnetic fields generated by the electrical activity of neurons at local scale like action potentials which have an amplitude expected between 10 and 100 pT at 1 kHz. As GMR sensors have a limit of detection (LOD) in the nT range at low frequency, several studies were conducted, including on the size and composition of the GMR sensor, to improve it. A probe that implements GMR sensors to conduct in-vivo experiments, called magnetrode, was also optimized in two ways. First, the tip thickness is reduced to decrease its invasiveness. Second, several GMR sensors are embedded on the magnetrode and in particular for 2D measurements. The optimized magnetrodes were then used for in-vivo recordings on rodents. They keep a limit of detection of 1 nT around 1 kHz for an increased stability which enables the reduction of the noise level of in-vivo experiments thanks to an averaging over a large number of events. In addition, a magnetrode for 2D measurements was developed. Finally, GMR sensors at the state of the art are implemented on a magnetrode with a tip thickness decreased down to 25 µm. Magnetrodes are able to detect in-vivo a magnetic signal with an amplitude around 250 pT
3
Thomas, Ian. "High resolution measurements of quasi-static biomagnetic fields." Thesis, Open University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.278302.
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Cameron, Seth Andrew 1967. "Novel Fourier methods for biomagnetic boundary value problems." Thesis, The University of Arizona, 1990. http://hdl.handle.net/10150/278738.
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A novel Fourier technique for solving a wide variety of boundary value problems is introduced. The technique, called Fourier projection, is based on the geometric properties of vector calculus operators in reciprocal space. Fourier projection decomposes arbitrary vector fields into collections of irrotational and/or divergenceless dipole subfields. For well-posed problems, Fourier projection algorithms can calculate unknown field values from a knowledge of primary sources and boundary conditions. Specifically, this technique is applied to several problems associated with biomagnetic imaging, including volume current calculations and equivalent surface current solutions. In addition, a low-cost magnetic field mapping system designed to aid reconstruction algorithm development is described.
5
Singh, Krishna Devi. "The development of biomagnetic systems : planar gradiometers and software tools." n.p, 1991. http://oro.open.ac.uk/19786/.
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Hrkac, Viktor [Verfasser]. "Nanocharacterization of materials for biomagnetic sensing using TEM / Viktor Hrkac." Kiel : Universitätsbibliothek Kiel, 2014. http://d-nb.info/1047578808/34.
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Singh, K. D. "The development of biomagnetic systems : planar gradiometers and software tools." Thesis, Open University, 1991. http://oro.open.ac.uk/19786/.
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This thesis is concerned with two aspects of the design and construction of biomagnetic systems. Firstly, it considers the optimum design of planar gradiometers. The modelling of gradiometers is discussed and an algorithm for optimising the sensitivity of a specific type of gradiometer is presented. A test thin-film procedure for the manufacture of a planar gradiometer is outlined. The performance of three different types of gradiometer in recovering test current distributions, using a distributed current analysis technique, is assessed. Secondly, four major software tools that are essential in the analysis of data from large multi-channel biomagnetic systems are presented. These tools are then used to analyze data from a visual evoked response experiment. The system used to collect data was the Helsinki multi-channel system which consists of 24 planar gradiometers. The results confirm the retinotopic mapping of visual field information, and suggest that the time evolution of activity in different parts of the visual cortex is similar for early latencies.
8
Moura, Matheus Sacilotto de. "Desenvolvimento em um biogradiômetro multicanal supercondutor com SQUIDs DC para registro de medidas de magnetocardiografia fetal." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/59/59135/tde-04042012-141710/.
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Neste projeto trabalhou-se no desenvolvimento de uma nova instrumentação para registrar medidas de campos magnéticos de origem biológica baseados em sensores SQUID e sistemas auxiliares, com o objetivo de usar este arranjo na aquisição de medidas de magnetocardiografia fetal (MCGf), que consiste no registro dos campos magnéticos gerados pela atividade cardíaca fetal, refletindo seus processos eletrofisiológicos. Esta técnica biomagnética além de ser bastante precisa para obter medidas de campo magnético originado do coração fetal, que é da ordem de dez picoteslas a poucos centímetros de distância do abdômen materno, também realiza medidas de forma não-invasiva, o que a torna bastante promissora. Contudo, não se conseguiu a sensibilidade desejada do sistema biogradiométrico, sendo alcançada uma sensibilidade capaz de detectar o sinal magneto-cardiográfico (MCG) de um sistema cardíaco desenvolvido, que é da ordem de 100 pT. Neste trabalho reuniu-se, ainda, toda a informação obtida pelo grupo de biomagnetismo no decorrer dos últimos anos referente ao sistema biogradiométrico multicanal.In this project we worked in the developing of a new instrumentation for mea- sure magnetic fields of biological source based in SQUID sensors and auxiliares systems, with aim of use this suite in measures of fetal magnetocardiography (fMCG), that is the recording of the magnetic fields generated by the fetal heart's activity, reflecting the electrophysiological processes that happen in it. This biomagnetic technique besides to be accurate enough to obtain measures of the magnetic field originated from the fetal heart, that is of the order of ten picoteslas at a few centimeters distance from the maternal abdomen, also realizes measures in outside sections at the mother's body turning it so promise. However, not obtained the desired sensitivity of the biogradiometer system, achieving just a sensitivity capable of detecting the magnetocardiography (MCG) signal of a developed cardiac system, which is about 100 pT. This work has met, yet, all information obtained by the biomagnetism group over the past years referent to the multichannel biogradiometer system.
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OTERO, JOHNNY ALEXANDER BASTIDAS. "GENETIC ALGORITHMS APPLIED TO THE SOLUTION OF THE BIOMAGNETIC INVERSE PROBLEM." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2016. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=28372@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE EXCELENCIA ACADEMICA
Sinais bioelétricos fornecem informações importantes sobre a função fisiológica de muitos organismos vivos. Em magnetismo, denomina-se problema direto aquele em que se determina o campo magnético a partir do conhecimento da fonte de corrente que o gerou. Por outro lado, existem situações em que se deseja determinar a fonte de corrente a partir de valores de campo magnético medidos. Esse tipo de problema é usual em Biomagnetismo e é denominado problema inverso. Por exemplo, com base em medições do campo magnético cardíaco é possível inferir sobre a atividade elétrica, no tecido cardíaco, que foi responsável por sua geração. Este trabalho propõe, apresenta e discute uma nova técnica destinada a resolver o problema biomagnético inverso, por meio de algoritmos genéticos. Objetiva-se estimar a posição, a orientação e a magnitude dos dipolos de corrente equivalentes, responsáveis pela geração de mapas de campos biomagnéticos obtidos experimentalmente por meio de medições realizadas em corações isolados de coelho utilizando um sistema SQUID de 16 canais. O algoritmo busca identificar a distribuição de dipolos que melhor se ajusta aos dados experimentais, objetivando minimizar o erro entre o mapa de campo magnético medido e o obtido por meio das soluções estimadas. O conhecimento dos parâmetros dos dipolos de corrente, em diferentes instantes de tempo, permite a correta interpretação e análise da informação médica obtida a partir dos campos biomagnéticos medidos experimentalmente, auxiliando na definição de diagnósticos e orientação de abordagens terapêuticas.
Bioelectric signals provide important information about the physiological function of many living organisms. In magnetism, the so-called direct problem deals with the determination of the magnetic field associated to well known current sources. On the other hand, there are situations where it is necessary to determine the current source responsible for the generation of a measured magnetic field. This type of problem is common in Biomagnetism and is called inverse problem. For example, based on cardiac magnetic field measurements it is possible to infer the electrical activity in the heart tissue, responsible for its generation. This work proposes, presents and discusses a new technique designed to solve the biomagnetic inverse problem by genetic algorithms. It is intended to estimate the position, orientation and magnitude of the equivalent current dipoles, responsible for the generation of biomagnetic field maps measured with a 16 channel SQUID system. The algorithm attempts to identify the distribution of dipoles that best fits the measured experimental data, aiming at minimizing the error between the experimental magnetic field maps and those obtained by the estimated solutions. The experimental data analyzed in this study were acquired by measurements in isolated rabbit hearts. The knowledge of parameters of current dipoles at different instants of time allows the correct interpretation and analysis of medical information obtained from the experimentally measured biomagnetic fields, providing diagnosis and guiding therapeutic procedures.
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Gyawali, Shashi Raj. "Design and construction of helmholtz coil for biomagnetic studies on soybean." Diss., Columbia, Mo. : University of Missouri-Columbia, 2008. http://hdl.handle.net/10355/5686.
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Thesis (M.S.)--University of Missouri-Columbia, 2008.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on August 12, 2009) Includes bibliographical references.
11
Janday, B. S. "Biomagnetic field measurements and their interpretation using the dipole in a sphere model." Thesis, Open University, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380062.
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Hansard, Ruth Claire. "Evaluation and application of biomagnetic monitoring of industry and vehicle-derived particulate pollution." Thesis, Lancaster University, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.654539.
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Clear association exists between exposure to even small concentrations of ambient atmospheric particles with an aerodynamic diameter < 10 Ilm (PMIO) and adverse health outcomes. However, determination of the strength of associations between exposure and illness is limited by low spatial-resolution of particulate concentration measurements. Conventional fixed monitoring stations provide high temporal-resolution data, but cannot capture fine-scale spatial variations. Biomagnetic monitoring of PMIO deposited on tree leaves may provide a means of obtaining exposure data at high spatial resolution. To calculate ambient PMIO concentrations from leaf magnetic values, the relationship between the magnetic signal and total PMIO mass and leaf exposure time must be quantified. This thesis uses magnetic remanence measurements of roadside tree leaves and co-located pumped air filters to examine levels of vehicle - and industry - derived PMIO at three locations within the UK. At the roadside, leaf saturation remanence (SIRM) values exhibit strong correlation with both the SIRM and particulate mass of co-located, pumped-air samples, indicating that these leaf magnetic values are an effective proxy for ambient PMIO concentrations. Two broadleaf deciduous species reach dynamic equilibrium between leaf magnetic remanence and ambient PMIO over a relatively short timescale (- 6 days), indicating that the leafcalculated PMIO reflects ambient PMIO concentrations. Multiple co-located species can be robustly inter-calibrated, enabling maximisation of the spatial resolution of this technique. A different but equally strong correlation also exists between leaf SIRM and ambient PMIO around a major industrial point source. To reduce ambient PMIO concentrations, it is often necessary to identify particulate sources, particularly in complex areas where multiple sources are present andlor in complex topography. To address this issue, I combine magnetic measurements of tree leaves, putative To address this issue, I combine magnetic measurements of tree leaves, putative 11 I J 'j 11 :1 :Ij, :1 :1 I 'I , , , a -------- ,-~-- --------- sources and road dusts to examine if magnetic differentiation can be made between the potential sources and sinks. Particulate assemblages emitted from vehicle fleets (e.g. diesel/petrol) and a range of industrial sources differ in their measured magnetic characteristics, indicating the value of magnetic techniques for particulate source attribution.
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Ni, Cheng. "Studies of magnetisation and active biomagnetic sources in human subjects by using SQUID magnetometers." Thesis, University of Southampton, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.238883.
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Hayes, Patrick [Verfasser], Eckhard [Akademischer Betreuer] Quandt, and Reinhard [Gutachter] Knöchel. "Converse Magnetoelectric Resonators for Biomagnetic Field Sensing / Patrick Hayes ; Gutachter: Reinhard Knöchel ; Betreuer: Eckhard Quandt." Kiel : Universitätsbibliothek Kiel, 2020. http://d-nb.info/1233679023/34.
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SILVA, EDUARDO COSTA DA. "DEVELOPMENT OF A TRANSDUCER BASED ON THE PHASE OF THE GIANT MAGNETOIMPEDANCE FOR THE MEASUREMENT OF BIOMAGNETIC FIELDS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2010. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=16687@1.
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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOREsta dissertação tem por objetivo o desenvolvimento de um transdutor magnético baseado no efeito da Magnetoimpedância Gigante (GMI – Giant Magnetoimpedance), destinado à medição de campos biomagnéticos. A motivação deste trabalho advém da inexistência de um sistema de baixo custo capaz de medir satisfatoriamente campos biomagnéticos, operando à temperatura ambiente e em plena conformidade com os princípios biometrológicos. Por sua vez, a metodologia experimental empregada iniciou-se pela medição e minuciosa análise das características de módulo e fase de sensores GMI em função do campo magnético, verificando-se suas dependências em relação ao comprimento das amostras e ao nível CC e frequência da corrente de excitação. Também, investigou-se a histerese e a homogeneidade das amostras GMI. Em seguida, foram idealizados circuitos eletrônicos para condicionamento e leitura das amostras GMI, destacando-se a estrutura desenvolvida que possibilita a leitura gradiométrica e algumas configurações inovadoras que permitem tanto a amplificação da sensibilidade de fase dos sensores GMI quanto a homogeneização das características de fase. Os resultados obtidos para o melhor transdutor magnético GMI desenvolvido, o qual é baseado na fase da impedância, apresentou uma elevada sensibilidade (250 mV/nT), indicando ganhos superiores a 1500 vezes quando comparado a protótipos baseados no módulo e, consequentemente, possibilitando alcançar novos patamares de resolução. Como conclusão ressaltase o grande potencial do magnetômetro GMI desenvolvido, caracterizado por seu baixo custo e elevada sensibilidade, quanto a sua aplicabilidade na medição de campos magnéticos ultra-fracos e, em especial, de campos biomagnéticos. Assim, o presente desenvolvimento contribui para a difusão das técnicas diagnósticas baseadas na medição de campos biomagnéticos, no ambiente clínico-hospitalar.
This M.Sc. dissertation aims at developing a magnetic field transducer based on the Giant Magnetoimpedance (GMI) effect to be applied on the measurement of biomagnetic fields. The motivation of this work stems from the lack of a low cost system capable of adequately measuring biomagnetic fields, operating at room temperature and in full conformity with the biometrological principles. On the other hand, the experimental methodology began by measuring and carefully analyzing the impedance magnitude and phase characteristics of GMI sensors as a function of the magnetic field, verifying their dependencies on the length of the samples and on the DC level and frequency of the excitation current. It was also investigated the hysteresis and the homogeneity of GMI samples. In turn, the electronic circuits for conditioning and reading of GMI samples were developed, highlighting the developed structure that enables a gradiometric reading and some innovative configurations that allow both the enhancement of the impedance phase sensitivity of GMI sensors and the homogenization of their impedance phase characteristics. The results obtained for the best GMI magnetic transducer developed, which is based on the impedance phase, showed a high sensitivity (250 mV/nT), indicating gains of more than 1500 times when compared to magnitude-based prototypes and, consequently, reaching much better resolution levels. In conclusion it is emphasized the great potential of the developed GMI magnetometer, characterized by its low cost and high sensitivity, as to its applicability in measuring ultra-weak magnetic fields and in particular biomagnetic fields. Thus, the present development contributes to the spread of diagnostic techniques based on the measurement of biomagnetic fields, in clinical and hospital environments.
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Wolff, Niklas [Verfasser], Lorenz [Akademischer Betreuer] Kienle, Rainer [Gutachter] Adelung, and David C. [Gutachter] Johnson. "Nanocharacterization of Functional Materials for Biomagnetic Sensing an Breath Analysis / Niklas Wolff ; Gutachter: Rainer Adelung, David C. Johnson ; Betreuer: Lorenz Kienle." Kiel : Universitätsbibliothek Kiel, 2020. http://d-nb.info/1213724287/34.
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Davies, Gareth. "Measurement methods in biomagnetism." Thesis, Imperial College London, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267283.
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Lang, Gillian. "SQUID gradiometers fo biomagnetism." Thesis, University of Strathclyde, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366811.
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Nantel, Normand P. "Biomagnetism, stimulating and recording muscle activity." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0003/NQ42756.pdf.
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Grimes, David. "Two methods of modelling electric current systems by analysis of magnetic field data, with particular reference to the quasi-dc magnetic field of the human leg." Thesis, Open University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329113.
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KUHNER, GUILHERME SESTO. "DIGITAL CONTROL OF A PNEUMATIC POSITIONING SYSTEM FOR BIOMAGNET MEASUREMENTS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1996. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=9376@1.
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Este trabalho apresenta uma solução para o problema de
posicionamento automático preciso de um corpo em um plano
horizontal, atendendo à restrição de não gerar campo
magnético significativo junto ao objeto a ser posicionado.
A motivação do trabalho reside na necessidade, por parte
do Laboratório de Supercondutividade Aplicada e Magnetismo
(LSAM) do Departamento de Física, de um posicionador para
experimentação em magnetocardiografia.
Inicialmente são discutidas as tecnologias de
automação aplicáveis ao problema, justificando-se a opção
por um sistema pneumático de atuação. O sistema posicionar
montado é então descrito em profundidade, abordando-se os
aspectos relacionados à geometria do problema em questão,
materiais, montagens mecânicas e o sistema de controle
digital.
A seguir é apresentada uma abordagem matemática
para o problema de controle de posição em malha fechada,
visando à definição de uma lei de controle aplicável ao
caso em estudo. Alguns resultados analíticos são obtidos
para controle de sistema caracterizados por atrito
Coulombiano, ao mesmo tempo em que se desenvolve um modelo
para simulação numérica da dinâmica de movimento do
posicionador. Com base nestas duas ferramentas, é
apresentada uma discussão sobre a aplicabilidade dos
controladores da família PID ao caso específico
considerado. Por fim, resultados reais obtidos com a lei
de controle proposta são comparadores aos resultados
simulados, mostrando-se a validade e a utilidade do modelo
teórico.This thesis presents a solution or the problem of automatic precise positioning of na object in the horizontal plane, not generating any significative magnetic field in the region close to the object to be positioned. The study presented was developed as part of an effort to fulfill a necessity for a positioning system for magnetocardiography experimentation in the Magnetism and Applied Supercondutivity Laboratory of the Departament of Physics of this University. A discussion over applicable automation option is presents, along with a justification for a choice of a pneumatic actuating system. The whole precise positioning assembly is described in detail, including subjects such as movement geometry, material, mechanical structures and the digital control system. A mathematical study of the closed of the closed loop position control problem is then developed, aiming to define a control algorithm applicable to the problem. Algebraic analysis is used to describe the influence of Coulomb friction over the equations of motion of a proportional position control system, while a model for simulations experiments of the assembly´s positioning dynamics is developed. These tools are used as the basis for a discussion over the applicability of the PID controlers in the case in study. Moreover, the behavior of the proposed algorithm is recorded and compared to the results of the simulations, showing the correctness and the utility of the theoretical analysis.
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Colbeck, H. "Magnetic field effects in model membrane systems." Thesis, University of Southampton, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382939.
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Zolj, Adnan. "Electrically Small Dipole Antenna Probe for Quasi-static Electric Field Measurements." Digital WPI, 2018. https://digitalcommons.wpi.edu/etd-theses/202.
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The thesis designs, constructs, and tests an electrically small dipole antenna probe for the measurement of electric field distributions induced by a transcranial magnetic stimulation (TMS) coil. Its unique features include high spatial resolution, large frequency band from 100 Hz to 300 kHz, efficient feedline isolation via a printed Dyson balun, and accurate mitigation of noise. Prior work in this area is thoroughly reviewed. The proposed probe design is realized in hardware; implementation details and design tradeoffs are described. Test data is presented for the measurement of a CW capacitor electric field, demonstrating the probe’s ability to properly measure conservative electric fields caused by a charge distribution. Test data is also presented for the measurement of a CW solenoidal electric field, demonstrating the probe’s ability to measure non-conservative solenoidal electric fields caused by Faraday’s law of induction. Those are the primary fields for the transcranial magnetic stimulation. Advantages and disadvantages of this probing system versus those of prior works are discussed. Further refinement steps necessary for the development of this probe as a valuable TMS instrument are discussed.
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Stelzer, Murilo [UNESP]. "Biosusceptometria de corrente alternada: tomografia, validação e avaliação da motilidade fúndica gástrica." Universidade Estadual Paulista (UNESP), 2011. http://hdl.handle.net/11449/100599.
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stelzer_m_dr_botib.pdf: 918862 bytes, checksum: bc6a3bc2154c49c9ab02546521651045 (MD5)O estudo da atividade do sistema digestório apresenta vários desafios, pois para termos medidas eficientes do seu funcionamentos as técnicas atualmente aplicadas ou são invasivas ou apresentam o uso de radiação ionizante, o que pode causar desconforto ou outros problemas ao individuo. ABiosusceptometria de Corrente Alternada (BAC), tem sido utilizada com sucesso no estudo da motilidade do trato gastrintestinal, sem a necessidade de radiação ionizante e sem ser invasiva.Essatese foi desenvolvida em três partes, com cada parte representando um trabalho, no primeiro foi estudado aOscilação Tônica no Estomago Proximal, no segundo foi feita a validação da BAC in vitro e in vivo como um método biomagnético para registrar contrações gástricas e finalmente no terceiro foi iniciado o desenvolvimento de uma nova instrumentação de modo a permitir a obtenção de imagens tomográficas utilizando a BAC. Desta forma, este trabalho apresenta estudos de validações da BAC para análise das atividades de contração tônica e fásica do estômago e de emprego como técnica tomográfica
The evaluation of gastric-intestinal activity presents a lot of challenges, because, the techniques to obtain efficient measures or is an invasive technique or it makes use of ionizing radiation, what could cause some discomfort or another problems related to the radiation. The Alternated Current Biosusceptometry (ACB) has been utilized with success, in the gastricintestinal activity studies, without the necessity of ionizing radiation and it isn´t a invasive method. This thesis has been developed in three parts, in the first part was studied the stomach proximal tonic oscillation, in the second was studied the validation of theACB method in vitro and in vivo as a biomagnetic method to register the gastric contractions, and finally the third, it was started the development of a new instrumentation capable of obtain tomography images by means of BAC
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Bruno, Antonio Carlos Oliveira. "Gradiômetros supercondutores acoplados a SQUIDs e sua aplicação em biomagnetismo." Universidade de São Paulo, 1990. http://www.teses.usp.br/teses/disponiveis/54/54132/tde-19052009-095436/.
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O objetivo desta tese foi o estudo da detecção de campos magnéticos fracos através da utilização de gradiômetros supercondutores acoplados à SQUIDs e sua aplicação ao biomagnetismo. Um novo modelo teórico para descrição do gradiômetro foi desenvolvido com a obtenção da sua função de transferência espacial. Através desta função de transferência a atuação do gradiômetro sobre os sinais detectados pode ser quantificada. Além disso, foi desenvolvido para a medida experimental da função de transferência, onde as imperfeições no processo de construção do sensor podem ser medidas e avaliadas. Foi proposta uma nova terminologia para descrição do gradiômetro ao invés de sua descrição física. Nesta terminologia, o gradiômetro ficará especificado pelo seu roll off, freqüência de corte espacial e ganho máximo. Também foi generalizado o método para projeto de gradiômetros onde novas configurações podem ser construídas e testadas. A partir da obtenção desta função de transferência um método para calibração tesla /volt do sistema foi desenvolvido, com uma precisão até então não alcançada por outros métodos e perfeitamente apropriado para utilização em sistemas multicanais. Finalmente foi desenvolvido um algorítimo de desconvolução para, a partir de sinais detectados com gradiômetros planares, recuperar o sinal original como ele tivesse sido detectado somente por uma bobina. Este algorítmo também pode ser utilizado para auxílio no projeto de arrays destes gradiômetros.The objective of this thesis was to study the detection of weak magnetic fields through the use of superconducting gradiometers coupled to SQUIDs and its application to biomagnetism. A new theoretical model for the specification of the gradiometer was developed by obtaining its spatial transfer function. Through the transfer function the signal detected by the gradiometer can be quantified. Besides, a procedure was developed to experimentally measure the spatial transfer, where the imperfections in the construction process of the sensor can be measured and evaluated. A new terminology was proposed for specification of the gradiometer instead of his physical description. Using this terminology, the gradiometer will be specified by its roll off, spatial cutoff frequency and maximum gain. Also the method was generalized for design of gradiometers where new configurations can be built and tested. From the transfer function a method for tesla/volt calibration of the system was developed. Finally a deconvolution algorithm was developed, that from signals detected by the gradiometer the original signal can be recovered. This algorithm also can be used in the design of gradiometer arrays.
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Stelzer, Murilo. "Biosusceptometria de corrente alternada : tomografia, validação e avaliação da motilidade fúndica gástrica /." Botucatu : [s.n.], 2011. http://hdl.handle.net/11449/100599.
Full textAbstract:
Orientador: José Ricardo de Arruda MirandaBanca: Andrés Vercik
Banca: Sérgio Paulo Amaral Souto
Banca: José Roberto Corrêa Saglietti
Banca: Eder Rezende Moraes
Resumo: O estudo da atividade do sistema digestório apresenta vários desafios, pois para termos medidas eficientes do seu funcionamentos as técnicas atualmente aplicadas ou são invasivas ou apresentam o uso de radiação ionizante, o que pode causar desconforto ou outros problemas ao individuo. ABiosusceptometria de Corrente Alternada (BAC), tem sido utilizada com sucesso no estudo da motilidade do trato gastrintestinal, sem a necessidade de radiação ionizante e sem ser invasiva.Essatese foi desenvolvida em três partes, com cada parte representando um trabalho, no primeiro foi estudado aOscilação Tônica no Estomago Proximal, no segundo foi feita a validação da BAC in vitro e in vivo como um método biomagnético para registrar contrações gástricas e finalmente no terceiro foi iniciado o desenvolvimento de uma nova instrumentação de modo a permitir a obtenção de imagens tomográficas utilizando a BAC. Desta forma, este trabalho apresenta estudos de validações da BAC para análise das atividades de contração tônica e fásica do estômago e de emprego como técnica tomográfica
Abstract: The evaluation of gastric-intestinal activity presents a lot of challenges, because, the techniques to obtain efficient measures or is an invasive technique or it makes use of ionizing radiation, what could cause some discomfort or another problems related to the radiation. The Alternated Current Biosusceptometry (ACB) has been utilized with success, in the gastricintestinal activity studies, without the necessity of ionizing radiation and it isn't a invasive method. This thesis has been developed in three parts, in the first part was studied the stomach proximal tonic oscillation, in the second was studied the validation of theACB method in vitro and in vivo as a biomagnetic method to register the gastric contractions, and finally the third, it was started the development of a new instrumentation capable of obtain tomography images by means of BAC
Doutor
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Agostinho, Marcelo Rodrigues [UNESP]. "Otimização e aperfeiçoamento BAC pra estudos envolvendo o trato gastrintestinal." Universidade Estadual Paulista (UNESP), 2011. http://hdl.handle.net/11449/91672.
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A utilização de técnicas não invasivas, de baixo custo e inócuas ao indi-víduo proporcionam um grande desafio para o estudo do trato gastrintestinal. Métodos biomagnéticos como a BAC trazem todas essas vantagens e incluem a possibilidade de expansão para novos estudos, arranjos instrumentais e mo-delos biológicos. A consolidação dessa técnica nos últimos anos permitiu a ampliação dos estudos na área farmacêutica, avaliações após alterações nas condições fisiológicas e mesmo após administração de drogas, fornecendo subsídios para uma melhor interpretação dos parâmetros motores do trato gas-trintestinal. As imagens de traçadores e marcadores magnéticos no trato gas-trintestinal proporcionadas pela BAC foi um importante aspecto explorado, no entanto, houve a necessidade de aperfeiçoar a instrumentação para obter me-lhores e também novos resultados. A proposta de implementação de algumas melhorias nesta instrumentação através de implementação de novo arranjo de bobina excitadora, cancelamento de ruído respiratório e nova eletrônica de de-tecção permitiram que os dados in vitro e in vivo refletiram numa melhor quali-dade de sinais e imagens obtidos por este técnica. A BAC multi-sensores é uma ferramenta valiosa com vasta aplicabilidade para aplicação em tecnologia farmacêutica e em fisiologia do trato gastrintestinal
The use of non-invasive techniques, at low cost and harmless to the indi-vidual, provides a great challenge for the study of the gastrointestinal tract. Biomagnetic methods such as the BAC have all these advantages and also include the possibility of expanding to new studies, to instrumental ar-rangements and to biological models. The consolidation of this technique in re-cent years allowed the extension of studies in the pharmaceutical field, after rating changes in physiological conditions and even after drug administration, supporting a better interpretation of the motor parameters of the gastrointestinal tract. The images of tracers and magnetic markers in the gastrointestinal tract offered by the BAC was an important aspect explored. However, there was a necessity of improving the equipment in order to obtain new and better re-sults. The proposal to implement some improvements in this equipment through implementation of the new exciter coil arrangement, the cancellation of the noise of breathing, and the new electronics of detection have allowed that the data in vitro and in vivo reflected a better quality of signals and images obtained by this technique. The BAC multi-sensors is a valuable tool with wide applica-bility to pharmaceutical technology and physiology of the gastrointestinal tract
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Andreis, Uilian de [UNESP]. "Farmacomagnetografia colônia: estudo in vitro da desintegração de comprimidos magnéticos revestidos." Universidade Estadual Paulista (UNESP), 2010. http://hdl.handle.net/11449/102442.
Full textAbstract:
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A avaliação dos parâmetros motores do trato gastrintestinal é condição necessária para caracterizar o comportamento de formas farmacêuticas sólidas administradas pela via oral. A função motora gastrintestinal pode ser alterada em detrimento de doenças, interações com medicamentos ou intervenções cirúrgicas. Essas alterações, por sua vez, podem influenciar diversos processos farmacêuticos e, consequentemente, a biodisponibilidade dos fármacos. Comprimidos são as formas farmacêuticas mais utilizadas na terapia. Para garantir a eficácia e segurança dessas preparações, são necessários testes in vitro que simulam o trato gastrintestinal. Entretanto, não é possível estimar com precisão a influencia dos parâmetros gastrintestinais na liberação do fármaco. Por essa razão, os ensaios in vivo realizados por técnicas não invasivas e inócuas ao indivíduo são necessários, pois permitem monitorar simultaneamente os parâmetros motores e suas interrelações com os processos de liberação e biodisponibilidade dos fármacos. O objetivo desse trabalho foi empregar a técnica de Biosusceptometria AC associada à farmacocinética para avaliar a influência da motilidade gastrintestinal, bem como das alterações induzidas nessa função pela administração prévia de um procinético (Domperidona) e um antimuscarínico (Butilbrometo de Escopolamina). Além disso, foram avaliadas as influências desses parâmetros no processo de liberação e biodisponibilidade de um fármaco modelo (Diclofenaco Sódico) adicionado a comprimidos revestidos
The evaluation of gastrointestinal motor parameters is necessary towards characterize the behavior of solid dosage forms orally administered. The gastrointestinal motor function may be altered by diseases, drugs or surgery. These alterations may influence a number of pharmaceutical processes and consequently the bioavailability of drugs. Tablets are the dosage forms most commonly used in therapy. To ensure the efficacy and safety of these formulations, in vitro tests in simulated gastrointestinal conditions are needed. However, such conditions as well as the influence of gastrointestinal parameters on drug release cannot be fully predicted. For these reasons, in vivo studies are realized by noninvasive and harmless techniques, since they allows monitoring gastrointestinal motor parameters and the relationships with drug delivery and bioavailability. The aim of this work was to employ the AC Biosusceptometry to evaluate the influence of gastrointestinal motility as well as the induced changes on this function by previous administration of a prokinetic drug (domperidone) and an antimuscarinic agent (scopolamine butilbromide). In addition, it have been evaluated how these alterations influenced the drug release and bioavailability of a model drug (sodium diclofenac) added to coated tablets
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Miranda, Jose Ricardo de Arruda. "Estudos biomagnéticos em fisiologia gástrica." Universidade de São Paulo, 1995. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-25032014-155116/.
Full textAbstract:
Este trabalho interdisciplinar apresenta três novas aplicações de diferentes métodos biomagnéticos para estudar características físicas da motilidade gástrica humana. Empregou-se um biosusceptômetro AC para medir a atividade mecânica de contração gástrica através do acompanhamento temporal dos traçadores magnéticos previamente ingeridos com um alimento teste (80 ml de iogurte e 3 g de ferrita em pó). Os registros gráficos foram obtidos de forma bastante satisfatória, mostrando ser esse método uma alternativa viável para a detecção e seguimento temporal dessa atividade, em condições normais e sob o efeito de drogas. Através do processo de relaxação de partículas previamente magnetizadas no interior do estômago e com o auxílio de um magnetômetro de saturação de fluxo, estudou-se o processo de mistura de um alimento teste no estômago. Um pulso de campo magnético de aproximadamente 600 G é aplicado sobre a região gástrica do voluntário contendo o alimento teste (80 ml de iogurte e 3 g de magnetita em pó), e o campo remanente é medido e acompanhado no tempo. Os resultados preliminares indicam que esse método apresenta um grande potencial para um maior entendimento das características físicas da função de mistura do estômago e também da atividade de contração do estômago. Novos estudos sob condições variadas de alimentação e drogas podem fornecer subsídios para uma melhor interpretação desse processo. Utilizando-se um magnetômetro supercondutor (SQUID-DC) mediu-se a atividade elétrica gástrica obtendo-se bons traçados temporais na maioria das medidas. Os registros indicam que através desse sistema podem-se realizar experimentos no intuito de diferenciar as atividades elétricas e também observar seu comportamento frente a diferentes condições clínicas. Os dados obtidos nesse trabalho mostram ser este enfoque um valioso instrumento que pode contribuir para um melhor entendimento das características físicas da motilidade gástrica e também possibilitar novos estudos sobre o sistema gastrointestinalThis interdisciplinary work presents three new applications of different biomagnetic methods to study physical characteristics of human gastric motility. A biosusceptometer was used to measure the mechanical activity of gastric contraction through a time to time checking of the magnetic tracers previously ingested by a volunteer along with a test food (80 ml of yogurt and 3g of ferrite in powder). Results in graphical recording were very satisfactory, indicating this method as a possible alternative to detect and also follow up that gastric activity, besides allowing the evaluation of related activity under the effect of drugs. Through the observation of the relaxation of previously magnetized particles in the stomach, measured with a fluxgate magnetometer, the process of mixing of the test food in stomach was studied. A strong pulse of magnetic field (600G) is applied externally to the stomach region of the volunteer who have already ingested the mentioned food test, whereas the remanent field is measured and followed up in time. Preliminary results indicate that this method provides a good understanding of the physical characteristics of the mixture of food and also of the stomach contraction activity. New studies of different types of food and drugs may provide further information on the process. A superconductor magnetometer (SQUID-DC) was used to measure the gastric electrical activity, and good temporal tracers were obtained for the majority of measurements. Recordings were of satisfactory quality, indicating that through that system, experiments can be carried out in order to differentiate the electrical activities and also to observe its behavior for different clinical conditions. Results obtained in this thesis to measure the gastric electromagnetic activity, indicate this to be a valuable tool to understand the physical characteristics of gastric motility, as well as to open new ways for studying the gastrointestinal system
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Corá, Luciana Aparecida [UNESP]. "A biosusceptometria AC aplicada à tecnologia farmacêutica." Universidade Estadual Paulista (UNESP), 2008. http://hdl.handle.net/11449/102448.
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A administração oral de drogas é uma prática comum na terapia e as formas farmacêuticas sólidas são amplamente utilizadas. A variação no perfil de absorção ao longo do trato gastrintestinal (TGI) humano e a possibilidade de liberar drogas em diferentes regiões são os maiores desafios para o desenvolvimento de novos produtos. Desse modo, avaliar formas farmacêuticas sólidas in vivo fornece um entendimento mais profundo quando um efeito sistêmico ou local é desejado. Geralmente, estes estudos são realizados por meio da cintilografia e técnicas biomagnéticas. A Biosusceptometria de Corrente Alternada (BAC) é uma técnica que merece destaque por suas características, acurácia dos resultados obtidos e versatilidade. A BAC propiciou imagens do processo de desintegração de comprimidos tanto in vitro quanto no estômago humano, introduzindo outra perspectiva na análise desse processo. Os resultados também foram correlacionados com sucesso com aqueles obtidos por metodologias específicas, garantindo uma análise mais acurada dos parâmetros físicos envolvidos com a desintegração de comprimidos. A utilização da BAC permitiu avaliar a motilidade gastrintestinal e o processo de desintegração de cápsulas de hidroxipropilmetilcelulose (HPMC) revestidas no cólon humano. Além disso, também foi possível investigar a influência do estado prandial no esvaziamento gástrico e no trânsito gastrintestinal de um sistema multiparticulado magnético. Todos esses trabalhos fortaleceram a BAC como um método alternativo na pesquisa farmacêutica demonstrando seu potencial para avaliar diferentes processos, apesar das suas limitações. Sintetizando, a BAC é uma ferramenta valiosa, com a vantagem de ser livre de radiação e inócua aos voluntários, e vasta aplicabilidade na pesquisa farmacêutica, farmacológica e fisiológica.
Oral administration is widely accepted route for drug delivery and solid dosage forms are commonly administered. The variation of absorption profiles along the human gastrointestinal tract (GIT) and the ability to target drugs by adequate dosage forms to distinct sites is the challenge in the pharmaceutical development of solid dosage forms. An understanding of the factors involved in drug absorption and how the gastrointestinal variables can interfere with this process is important to develop more reliable drug delivery systems. The performance of pharmaceutical dosage forms must be fully investigated in vivo to provide more reliable information when a local or systemic effect is desirable. Generally, in vivo investigation on the behavior of dosage forms has been made by using gamma‐scintigraphy and biomagnetic techniques. AC Biosusceptometry (ACB) deserves consideration due to its features, accuracy and versatility. By using ACB technique, it was possible to monitor the disintegration process through acquisition of magnetic images in vitro and in human stomach. The results also were successfully correlated with those obtained with standard methods which provided a more reliable analysis on the physical parameters involved in the disintegration process of tablets. ACB allowed evaluating the gastrointestinal motility and the disintegration of hydroxipropylmethylcellulose (HPMC) coated capsules in human colon. Moreover, it was possible to investigate the gastric emptying and gastrointestinal transit of a magnetic multiparticulate system under influence of prandial state. All these studies have contributed to establish the ACB as an alternative method for pharmaceutical research and, despite some limitations, it was feasible to evaluate different pharmaceutical processes. In summary, ACB is a radiation free and non‐invasive technique with wide applicability in pharmaceutical, physiological and pharmacological researches.
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Bolognesi, Leandro. "Avaliação do tempo de trânsito esofágico de formas farmacêuticas sólidas pela cintilografia e biosusceptometria AC /." Botucatu : [s.n.], 2008. http://hdl.handle.net/11449/87775.
Full textAbstract:
Orientador: José Ricardo de Arruda MirandaBanca: Luciana Aparecida Corá
Banca: Éder Rezende Moraes
Resumo: A administração oral de fármacos é uma prática comum na terapia e as formas farmacêuticas sólidas são amplamente utilizadas. O conhecimento sobre o trânsito de cápsulas e comprimidos no trato gastrointestinal é incompleto. Desse modo, avaliar o trânsito esofágico de farmacêuticas sólidas fornece um entendimento mais profundo sobre os mecanismos que desencadeiam a esofagite induzida por fármacos. Geralmente, os estudos de trânsito esofágico são realizados por meio da cintilografia, manometria e técnicas biomagnéticas, como o SQUID (Dispositivos Supercondutores de Interferência Quântica) e a Biosusceptometria de Corrente Alternada (BAC). A BAC é uma técnica que merece destaque por suas características, acurácia dos resultados obtidos e versatilidade. O objetivo do trabalho foi investigar a influência do tipo e peso da forma farmacêutica no tempo de trânsito esofágico e na velocidade de transporte no esôfago, além de estabelecer parâmetros comparativos entre os métodos cintilográfico e biomagnético empregados, para validar a BAC no estudo de trânsito esofágico de formas farmacêuticas sólidas. Cada um dos seis voluntários que participaram do estudo deglutiu com 50 ml de água cápsulas e comprimidos com 0,5, 0,8 e 1,0 gramas de ferrita, na cintilografia e na BAC. Para o estudo cintilográfico, a radiomarcação das formas farmacêuticas foi feita com 99mTc. Os resultados obtidos mostraram que o tipo e o peso da forma farmacêutica não influenciaram significativamente o tempo de trânsito esofágico e a velocidade de transporte no esôfago, embora os resultados estatísticos apontem para uma variação significativa para um número maior de voluntários. Além disso, uma comparação entre as técnicas permitiu validar a BAC como um método biomagnético para avaliar o trânsito... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Oral administration is a common practice in drug therapy and the solid dosage forms are widely used. Knowledge about esophageal transit of tablets and capsules is incomplete since it have been reported a number of injuries related to drug-induced esophageal damage. Esophageal transit time may be evaluated by employing gammascintigraphy, manometry, and biomagnetic techniques as SQUID and AC Biosusceptometry (ACB). ACB is a non-invasive and radiation free technique which enough versatility for a number of studies related to the gastrointestinal behavior of solid dosage forms. The aim of this work was to investigate the influence of different dosage forms (hard gelatin capsules and tablets) on the esophageal transit time and transport velocity in the esophagus upon to establish a comparison between the Scintigraphy and Biosusceptometry and to validate the ACB as a tool for esophageal transit studies. Six volunteers have participated in the study and they swallowed capsules and tablets with 0.5g, 0.8g and 1.0g of ferrite together 50 ml of water. For scintigraphic study, the dosage forms were labeled with 99mTc. The results showed that the parameters evaluated could not be significantly influenced by the different dosage forms administered. However, it could be observed that the results pointed out to a decrease in the transit time measured for dosage forms with lower weight. We have shown that ACB allowed investigating the influence of dosage forms parameters on the esophageal transit time in healthy volunteers with high spatiotemporal resolution. In summary, this study has allowed introducing the ACB as an alternative technique to investigate the esophageal transit of pharmaceutical dosage forms to understand the factors which could contribute to drug-induced esophageal damages.
Mestre
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Agostinho, Marcelo Rodrigues. "Otimização e aperfeiçoamento BAC pra estudos envolvendo o trato gastrintestinal /." Botucatu : [s.n.], 2011. http://hdl.handle.net/11449/91672.
Full textAbstract:
Orientador: José Ricardo de Arruda MirandaBanca: Eder Rezende
Banca: Fabiano Carlos Paixão
Resumo: A utilização de técnicas não invasivas, de baixo custo e inócuas ao indi-víduo proporcionam um grande desafio para o estudo do trato gastrintestinal. Métodos biomagnéticos como a BAC trazem todas essas vantagens e incluem a possibilidade de expansão para novos estudos, arranjos instrumentais e mo-delos biológicos. A consolidação dessa técnica nos últimos anos permitiu a ampliação dos estudos na área farmacêutica, avaliações após alterações nas condições fisiológicas e mesmo após administração de drogas, fornecendo subsídios para uma melhor interpretação dos parâmetros motores do trato gas-trintestinal. As imagens de traçadores e marcadores magnéticos no trato gas-trintestinal proporcionadas pela BAC foi um importante aspecto explorado, no entanto, houve a necessidade de aperfeiçoar a instrumentação para obter me-lhores e também novos resultados. A proposta de implementação de algumas melhorias nesta instrumentação através de implementação de novo arranjo de bobina excitadora, cancelamento de ruído respiratório e nova eletrônica de de-tecção permitiram que os dados in vitro e in vivo refletiram numa melhor quali-dade de sinais e imagens obtidos por este técnica. A BAC multi-sensores é uma ferramenta valiosa com vasta aplicabilidade para aplicação em tecnologia farmacêutica e em fisiologia do trato gastrintestinal
Abstract: The use of non-invasive techniques, at low cost and harmless to the indi-vidual, provides a great challenge for the study of the gastrointestinal tract. Biomagnetic methods such as the BAC have all these advantages and also include the possibility of expanding to new studies, to instrumental ar-rangements and to biological models. The consolidation of this technique in re-cent years allowed the extension of studies in the pharmaceutical field, after rating changes in physiological conditions and even after drug administration, supporting a better interpretation of the motor parameters of the gastrointestinal tract. The images of tracers and magnetic markers in the gastrointestinal tract offered by the BAC was an important aspect explored. However, there was a necessity of improving the equipment in order to obtain new and better re-sults. The proposal to implement some improvements in this equipment through implementation of the new exciter coil arrangement, the cancellation of the noise of breathing, and the new electronics of detection have allowed that the data in vitro and in vivo reflected a better quality of signals and images obtained by this technique. The BAC multi-sensors is a valuable tool with wide applica-bility to pharmaceutical technology and physiology of the gastrointestinal tract
Mestre
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Trubitsyn, Denis. "Magnetosome formation in marine vibrio MV-1." Thesis, University of Edinburgh, 2010. http://hdl.handle.net/1842/7589.
Full textAbstract:
Marine vibrio MV-1 is a magnetotactic bacterium capable of aligning its cell in response to the Earth’s magnetic field. This ability is due to the presence of chainlike structures comprising magnetosomes, magnetite particles enclosed in a lipid membrane with associated proteins. Strain MV-1 differs from other, bettercharacterized strains of magnetotactic bacteria as the cells produce higher amounts of biomagnetite per litre of culture and its magnetosomes are unique in shape. This study investigates the presence and organisation of a gene cluster termed a “magnetosome island” within the genome of MV-1. In other magnetotactic bacteria this genomic region has been shown to contain many of the genes associated with magnetosome formation but has not been previously investigated for MV-1. One of the conserved fragments of this region was amplified using degenerate primers followed by extension of the known sequence using inverse PCR based technique and constructing plasmid libraries. Sequencing of the genome of strain MV-1 was accomplished as a part of this study. Significant work was done on comparison of the sequence quality obtained from SOLEXA, 454 and Sanger sequencing technologies. A number of obtained contigs were joined manually and the resulting sequence was automatically annotated using RAST. The obtained genome sequence of 3.6 Mb with a G+C content of 54.3 % was preliminarily analysed and used to search for magnetosome related genes. This study also analysed proteins associated with the magnetosomes of strain MV-1 using MALDI-TOF, LC-MS and Orbitrap mass spectrometry. These approaches allowed the identification of a number of proteins in the isolated magnetosome membrane fraction. Some of these proteins have very low similarity with other characterized proteins (either in magnetotactic bacteria or in other organisms). Another significant point is that genes that code for proteins such as MamR, MamK and MmsF were found to be present in several homologous copies within the “magnetosome island” of MV-1. Interestingly, this study shows that all homologous copies of these proteins were identified in the magnetosome membrane fraction. Generation of knock-out mutants of several specific genes from the “magnetosome island” of strain MV-1 was attempted; constructs were made based on suicide plasmids carrying the cre-lox or I-SceI systems. Despite altering numerous experimental conditions it was not possible to obtain conclusive evidence of the isolation of MV-1 transconjugants containing the integrated constructs. In order to investigate the cell localization of the magnetosome associated protein CAV30779.1, an enhanced green fluorescent protein (EGFP) fusion based construct was generated and transferred into MV-1 cells. The EGFP fluorescent protein fusions within the cells were detected by microscopy. This study reveals novel information about magnetosome formation in marine vibrio MV-1. The obtained results provide an important foundation for further investigation of this organism and contribute towards broadening the knowledge of the complex process of magnetosome formation in bacteria.
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Andreis, Uilian de. "Farmacomagnetografia colônia : estudo in vitro da desintegração de comprimidos magnéticos revestidos /." Botucatu : [s.n.], 2010. http://hdl.handle.net/11449/102442.
Full textAbstract:
Orientador: José Ricardo de Arruda MirandaBanca: Luciana Aparecida Corá
Banca: Ricardo Brandit de Oliveira
Banca: Cristina Helena dos Reis Serra
Banca: José Ricardo Corrêa Saglietti
Resumo: A avaliação dos parâmetros motores do trato gastrintestinal é condição necessária para caracterizar o comportamento de formas farmacêuticas sólidas administradas pela via oral. A função motora gastrintestinal pode ser alterada em detrimento de doenças, interações com medicamentos ou intervenções cirúrgicas. Essas alterações, por sua vez, podem influenciar diversos processos farmacêuticos e, consequentemente, a biodisponibilidade dos fármacos. Comprimidos são as formas farmacêuticas mais utilizadas na terapia. Para garantir a eficácia e segurança dessas preparações, são necessários testes in vitro que simulam o trato gastrintestinal. Entretanto, não é possível estimar com precisão a influencia dos parâmetros gastrintestinais na liberação do fármaco. Por essa razão, os ensaios in vivo realizados por técnicas não invasivas e inócuas ao indivíduo são necessários, pois permitem monitorar simultaneamente os parâmetros motores e suas interrelações com os processos de liberação e biodisponibilidade dos fármacos. O objetivo desse trabalho foi empregar a técnica de Biosusceptometria AC associada à farmacocinética para avaliar a influência da motilidade gastrintestinal, bem como das alterações induzidas nessa função pela administração prévia de um procinético (Domperidona) e um antimuscarínico (Butilbrometo de Escopolamina). Além disso, foram avaliadas as influências desses parâmetros no processo de liberação e biodisponibilidade de um fármaco modelo (Diclofenaco Sódico) adicionado a comprimidos revestidos
Abstract: The evaluation of gastrointestinal motor parameters is necessary towards characterize the behavior of solid dosage forms orally administered. The gastrointestinal motor function may be altered by diseases, drugs or surgery. These alterations may influence a number of pharmaceutical processes and consequently the bioavailability of drugs. Tablets are the dosage forms most commonly used in therapy. To ensure the efficacy and safety of these formulations, in vitro tests in simulated gastrointestinal conditions are needed. However, such conditions as well as the influence of gastrointestinal parameters on drug release cannot be fully predicted. For these reasons, in vivo studies are realized by noninvasive and harmless techniques, since they allows monitoring gastrointestinal motor parameters and the relationships with drug delivery and bioavailability. The aim of this work was to employ the AC Biosusceptometry to evaluate the influence of gastrointestinal motility as well as the induced changes on this function by previous administration of a prokinetic drug (domperidone) and an antimuscarinic agent (scopolamine butilbromide). In addition, it have been evaluated how these alterations influenced the drug release and bioavailability of a model drug (sodium diclofenac) added to coated tablets
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Bolognesi, Leandro [UNESP]. "Avaliação do tempo de trânsito esofágico de formas farmacêuticas sólidas pela cintilografia e biosusceptometria AC." Universidade Estadual Paulista (UNESP), 2008. http://hdl.handle.net/11449/87775.
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bolognesi_l_me_botib.pdf: 259849 bytes, checksum: d7d575323f591bd0006aeb8a07bc7b2b (MD5)Universidade Estadual Paulista (UNESP)
A administração oral de fármacos é uma prática comum na terapia e as formas farmacêuticas sólidas são amplamente utilizadas. O conhecimento sobre o trânsito de cápsulas e comprimidos no trato gastrointestinal é incompleto. Desse modo, avaliar o trânsito esofágico de farmacêuticas sólidas fornece um entendimento mais profundo sobre os mecanismos que desencadeiam a esofagite induzida por fármacos. Geralmente, os estudos de trânsito esofágico são realizados por meio da cintilografia, manometria e técnicas biomagnéticas, como o SQUID (Dispositivos Supercondutores de Interferência Quântica) e a Biosusceptometria de Corrente Alternada (BAC). A BAC é uma técnica que merece destaque por suas características, acurácia dos resultados obtidos e versatilidade. O objetivo do trabalho foi investigar a influência do tipo e peso da forma farmacêutica no tempo de trânsito esofágico e na velocidade de transporte no esôfago, além de estabelecer parâmetros comparativos entre os métodos cintilográfico e biomagnético empregados, para validar a BAC no estudo de trânsito esofágico de formas farmacêuticas sólidas. Cada um dos seis voluntários que participaram do estudo deglutiu com 50 ml de água cápsulas e comprimidos com 0,5, 0,8 e 1,0 gramas de ferrita, na cintilografia e na BAC. Para o estudo cintilográfico, a radiomarcação das formas farmacêuticas foi feita com 99mTc. Os resultados obtidos mostraram que o tipo e o peso da forma farmacêutica não influenciaram significativamente o tempo de trânsito esofágico e a velocidade de transporte no esôfago, embora os resultados estatísticos apontem para uma variação significativa para um número maior de voluntários. Além disso, uma comparação entre as técnicas permitiu validar a BAC como um método biomagnético para avaliar o trânsito...
Oral administration is a common practice in drug therapy and the solid dosage forms are widely used. Knowledge about esophageal transit of tablets and capsules is incomplete since it have been reported a number of injuries related to drug-induced esophageal damage. Esophageal transit time may be evaluated by employing gammascintigraphy, manometry, and biomagnetic techniques as SQUID and AC Biosusceptometry (ACB). ACB is a non-invasive and radiation free technique which enough versatility for a number of studies related to the gastrointestinal behavior of solid dosage forms. The aim of this work was to investigate the influence of different dosage forms (hard gelatin capsules and tablets) on the esophageal transit time and transport velocity in the esophagus upon to establish a comparison between the Scintigraphy and Biosusceptometry and to validate the ACB as a tool for esophageal transit studies. Six volunteers have participated in the study and they swallowed capsules and tablets with 0.5g, 0.8g and 1.0g of ferrite together 50 ml of water. For scintigraphic study, the dosage forms were labeled with 99mTc. The results showed that the parameters evaluated could not be significantly influenced by the different dosage forms administered. However, it could be observed that the results pointed out to a decrease in the transit time measured for dosage forms with lower weight. We have shown that ACB allowed investigating the influence of dosage forms parameters on the esophageal transit time in healthy volunteers with high spatiotemporal resolution. In summary, this study has allowed introducing the ACB as an alternative technique to investigate the esophageal transit of pharmaceutical dosage forms to understand the factors which could contribute to drug-induced esophageal damages.
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Corá, Luciana Aparecida. "A biosusceptometria AC aplicada à tecnologia farmacêutica /." Botucatu : [s.n.], 2008. http://hdl.handle.net/11449/102448.
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Orientador: José Ricardo de Arruda MirandaBanca: Cristina Helena dos Reis Serra
Banca: Oswaldo Baffa Filho
Banca: Raul César Evangelista
Banca: Eryvaldo Sócrates Tabosa do Egyto
Resumo: A administração oral de drogas é uma prática comum na terapia e as formas farmacêuticas sólidas são amplamente utilizadas. A variação no perfil de absorção ao longo do trato gastrintestinal (TGI) humano e a possibilidade de liberar drogas em diferentes regiões são os maiores desafios para o desenvolvimento de novos produtos. Desse modo, avaliar formas farmacêuticas sólidas in vivo fornece um entendimento mais profundo quando um efeito sistêmico ou local é desejado. Geralmente, estes estudos são realizados por meio da cintilografia e técnicas biomagnéticas. A Biosusceptometria de Corrente Alternada (BAC) é uma técnica que merece destaque por suas características, acurácia dos resultados obtidos e versatilidade. A BAC propiciou imagens do processo de desintegração de comprimidos tanto in vitro quanto no estômago humano, introduzindo outra perspectiva na análise desse processo. Os resultados também foram correlacionados com sucesso com aqueles obtidos por metodologias específicas, garantindo uma análise mais acurada dos parâmetros físicos envolvidos com a desintegração de comprimidos. A utilização da BAC permitiu avaliar a motilidade gastrintestinal e o processo de desintegração de cápsulas de hidroxipropilmetilcelulose (HPMC) revestidas no cólon humano. Além disso, também foi possível investigar a influência do estado prandial no esvaziamento gástrico e no trânsito gastrintestinal de um sistema multiparticulado magnético. Todos esses trabalhos fortaleceram a BAC como um método alternativo na pesquisa farmacêutica demonstrando seu potencial para avaliar diferentes processos, apesar das suas limitações. Sintetizando, a BAC é uma ferramenta valiosa, com a vantagem de ser livre de radiação e inócua aos voluntários, e vasta aplicabilidade na pesquisa farmacêutica, farmacológica e fisiológica.
Abstract: Oral administration is widely accepted route for drug delivery and solid dosage forms are commonly administered. The variation of absorption profiles along the human gastrointestinal tract (GIT) and the ability to target drugs by adequate dosage forms to distinct sites is the challenge in the pharmaceutical development of solid dosage forms. An understanding of the factors involved in drug absorption and how the gastrointestinal variables can interfere with this process is important to develop more reliable drug delivery systems. The performance of pharmaceutical dosage forms must be fully investigated in vivo to provide more reliable information when a local or systemic effect is desirable. Generally, in vivo investigation on the behavior of dosage forms has been made by using gamma‐scintigraphy and biomagnetic techniques. AC Biosusceptometry (ACB) deserves consideration due to its features, accuracy and versatility. By using ACB technique, it was possible to monitor the disintegration process through acquisition of magnetic images in vitro and in human stomach. The results also were successfully correlated with those obtained with standard methods which provided a more reliable analysis on the physical parameters involved in the disintegration process of tablets. ACB allowed evaluating the gastrointestinal motility and the disintegration of hydroxipropylmethylcellulose (HPMC) coated capsules in human colon. Moreover, it was possible to investigate the gastric emptying and gastrointestinal transit of a magnetic multiparticulate system under influence of prandial state. All these studies have contributed to establish the ACB as an alternative method for pharmaceutical research and, despite some limitations, it was feasible to evaluate different pharmaceutical processes. In summary, ACB is a radiation free and non‐invasive technique with wide applicability in pharmaceutical, physiological and pharmacological researches.
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Lima, Eliane Aparecida de Andrade. "Padronização do metodo de isolamento de celulas natural killer uterinas (NKu) de camundongos atraves de biomagnetos conjugados com lectina Dolichos biflorus agluttin (DBA)." [s.n.], 2002. http://repositorio.unicamp.br/jspui/handle/REPOSIP/316562.
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Orientador : Aureo Tatsumi YamadaDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia
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Mestrado
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Faria, João Victor Carneiro. "Estudo da biodistribuição e determinação da eliminação de nanopartículas magnéticas em tempos longos por biosusceptometria de corrente alternada." Botucatu, 2020. http://hdl.handle.net/11449/192214.
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Orientador: José Ricardo de Arruda MirandaResumo: Nanopartículas magnéticas (NPMs) têm sido alvo de vários estudos por conta de sua versatilidade, que se destaca quando comparadas a outros materiais. NPMs apresentam tamanho reduzido, alta susceptibilidade magnética e devido a possibilidade de alteração química de revestimento, apresentam um alto poder teranóstico. Entretanto, antes de aplicá-los clinicamente é de extrema importância conhecer seus destinos e possibilidades de interação no organismo. A quantificação da biodistribuição de NPMs por meio de suas características intrínsecas ainda se mostra como um desafio. A Biosusceptometria de corrente alternada (BAC) é uma técnica biomagnética que atua detectando a quantidade de materiais magnéticos em ambientes biológicos. Essa técnica, em relação às demais presentes no mercado, apresenta baixo custo e portabilidade. Baseado na problemática em torno da detecção e quantificação de NPMs, nesse estudo foi analisada a biodistribuição e eliminação de NPMs de ferrita de manganês revestidas com citrato e albumina via sistema BAC. Para isso, foram utilizados 100 ratos Wistar, separados em 2 grupos experimentais (NPMs revestidas com albumina e citrato) e 10 subgrupos, variando o tempo de eutanásia dos animais (1, 4, 12, 24 e 48 horas e 5, 10, 15, 30 e 60 dias após a administração). Para análise da biodistribuição, foram coletados 5 órgãos de interesse: fígado, pulmão, baço, rins e coração, além do sangue e, para análise da eliminação, foram coletadas as fezes dos animais. Foi possível ... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Magnetic nanoparticles (MNPs) have been widely used in several studies due to their high versatility compared to other materials. MNPs presents small size, high magnetic susceptibility and, due to the possibility of biochemical alteration of its surface, enables a high level of theranostics applications. However, before applying them clinically, it is of paramount importance understand its destinations and possibilities of interaction in the organism. The biodistribution quantification of NPMs through their intrinsic characteristics still is a challenge. Alternating current biosusceptometry (ACB) is a biomagnetic technique that acts detecting a quantity of magnetic materials in biological samples. In comparison with the other techniques, ACB presents low cost and portability. Based on the lack of accessible techniques to study biodistribution and elimination process of MNPs, this work aimed to analyze the biodistribution and determine the elimination of manganese ferrite magnetic nanoparticles coated with citrate and albumin via BAC system. For this work, we used 100 Wistar rats, separated into 2 experimental groups (MNPs coated with albumin and citrate) and 10 subgroups, changing the euthanasia time point (1, 4, 12, 24 and 48 hours and 5, 10, 15, 30 and 60 days after administration). For biodistribution analysis, we collected the blood and 5 organs of interest: liver, lung, spleen, kidneys and heart, and, for elimination analysis, we collected the animal’s feces. It was poss... (Complete abstract click electronic access below)
Mestre
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Pannetier-Lecoeur, Myriam. "Superconducting-magnetoresistive sensor: Reaching the femtotesla at 77 K." Habilitation à diriger des recherches, Université Pierre et Marie Curie - Paris VI, 2010. http://tel.archives-ouvertes.fr/tel-00453410.
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Afin de permettre la mesure de champs magnétiques extrêmement faibles, comme ceux produits par l'activité neuronale lors des taches cognitives, nous avons proposé et réalisé un capteur femtotesla (10-15T) associant l'électronique de spin et la supraconductivité offrant une alternative en technologie couches minces et à 77K aux capteurs les plus sensibles actuellement que sont les SQUIDs (Superconducting Quantum Interference Devices) à basse température critique (4K). Le principe de base de ces capteurs, appelés capteurs mixtes, repose sur l'association d'un transformateur flux-champ très performant, obtenu grâce à une large boucle supraconductrice comprenant une constriction, et d'un capteur magnétique de type GMR ou TMR métallique de grande sensibilité. Des niveaux de détectivité de quelques fT/√Hz dans le bruit thermique ont pu ainsi être atteints à l'azote liquide, ce qui est comparable aux performances des SQUIDs à l'hélium liquide. Il existe cependant un bruit en 1/f à basse fréquence, dû au faible volume de l'élément magnétorésistif, qui limite les performances du capteur en dessous de 1kHz. Des techniques de suppression de ce bruit basse fréquence par bascule sur des points de référence du capteur sont étudiées et permettent déjà de réduire ce bruit de plus d'un ordre de grandeur, ce qui permet d'atteindre 0.1pT/√Hz à 1Hz. Grâce à ces capteurs, il a été possible de réaliser des premières mesures de la composante magnétique du signal cardiaque (signal de quelques pT/√Hz). Le très faible niveau de bruit thermique a permis également de réaliser des mesures de résonance quadrupolaire nucléaire sur des composés azotés qui est une technique de détection sélective d'explosifs. Nous avons aussi montré la possibilité de mesurer la résonance magnétique nucléaire du proton à très faible champ. Cela nous a conduit à développer un dispositif d'imagerie par résonance magnétique pour réaliser des images 3D à très bas champ (<20mT), ce qui présente un très grand intérêt pour la réalisation de systèmes d'IRM portables, faible coût, qu'il serait aussi possible d'intégrer dans un système de magnétoencéphalographie.
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Santos, Ruberlan de Oliveira. "Desenvolvimento de comprimidos de liberação prolongada de nimesulida contendo ferrita para avaliação do trânsito gastrintestinal por meio de técnica biomagnética." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/9/9139/tde-14052018-153106/.
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As Formas Farmacêuticas de Liberação Prolongada (FFLP) têm sido uma alternativa eficaz na terapia, pois proporcionam maior adesão do paciente ao tratamento em função da redução da frequência de dosagem ao longo do dia, sendo sua principal característica, a modulação da liberação/dissolução do fármaco. Entretanto, esta etapa pode ser influenciada por diferentes fatores, dentre eles: os físico-químicos relacionados ao fármaco; os farmacêuticos, principalmente relacionados aos excipientes empregados e às técnicas de obtenção da forma farmacêutica (FF) e os fisiológicos do trato gastrintestinal (TGI), como por exemplo, o pH dos líquidos do TGI, o tempo de esvaziamento gástrico, a motilidade intestinal, entre outros. Desse modo, a avaliação do trânsito da FF no TGI, após a sua administração, permite uma melhor compreensão dos fatores que podem afetar as etapas de liberação/dissolução do fármaco in vivo. Dentre as técnicas empregadas com esse objetivo, destacam-se: a cintilografia e os métodos biomagnéticos. A Biosusceptometria de Corrente Alternada (BAC) é um método biomagnético que tem se mostrado promissor para este tipo de estudo, por ser não invasivo, portátil, livre de radiação ionizante, e por apresentar acurácia e versatilidade. Diante do exposto, o presente trabalho teve como objetivos, desenvolver e caracterizar sob o aspecto biofarmacotécnico in vitro, um sistema de liberação prolongada contendo nimesulida (fármaco-modelo) e marcador magnético (ferrita), visando obtenção de ferramenta para avaliação do trânsito gastrintestinal por meio de técnica biomagnética. Para isto foram desenvolvidas quatro formulações de comprimidos de liberação prolongada contendo nimesulida, ferrita e diferentes concentrações de hidroxipropilmetilcelulose (HPMC): NF1 (30% HPMC); NF2 (23% HPMC); NF3 (17% HPMC) e NF4 (10% HPMC). Essas foram avaliadas quanto ao comportamento de dissolução por meio de ensaios com aparato 4 e avaliação da cinética e da eficiência de dissolução (ED%). Posteriormente, estudos biomagnéticos, in vitro e in vivo, foram conduzidos com emprego da técnica de BAC para a formulação selecionada. Os resultados obtidos mostraram que as 04 formulações desenvolvidas apresentaram porcentagens de dissolução distintas em função das diferentes concentrações de HPMC (NF1 = 13,2%; NF2 = 40,1%; NF3 = 72,5% e NF4 = 91,5%). A formulação NF4, com menor concentração de HPMC, foi escolhida para os estudos por meio de BAC em função dos resultados de ED% (54,3%) e por apresentar comportamento mais próximo de uma formulação de liberação prolongada. Em relação aos resultados de BAC in vitro, destaca-se que a formulação NF4 (10%HPMC) apresentou aumento de área magnética de forma independente do pH do meio, sugerindo que a hidratação/intumescimento da HPMC independe do pH. Em relação à avaliação do trânsito intestinal (estudo in vivo) foram obtidos os seguintes dados: Tempo médio de Residência Gástrica (TTR) - 89 minutos; Tempo médio do Trânsito Orocecal (TTO) - 313 minutos e Tempo médio do Trânsito Intestinal (TTI) - 224 minutos. Os dados de BAC in vivo permitiram observar que o aumento de área magnética atingiu um platô em cerca de 80 minutos após a administração da formulação NF4. A comparação dos dados de BAC in vitro e BAC in vivo, relacionados ao trânsito gastrintestinal, indica que a formulação NF4, após apresentar o ápice de intumescimento, foi capaz de manter sua estrutura permanente ao longo do TGI, favorecendo assim a liberação modulada do fármaco. Os resultados obtidos demonstraram que a formulação desenvolvida foi eficiente para avaliar e caracterizar o trânsito no TGI por meio da técnica de BAC e também permitiram uma estimativa do comportamento do fármaco em relação a solubilidade em cada porção do TGI, proporcionando assim uma ferramenta adequada para avaliação do trânsito do TGI e desenvolvimento de FFLP.Extended Release (ER) dosage forms have been an effective alternative in therapy, since they provide greater patient adherence to treatment as a function of the reduction of the frequency of dosing throughout the day, its main characteristic being the release / dissolution modulation of the drug. However, this stage can be influenced by different factors, among them: the physical and chemical related to the drug; the pharmacists, mainly related to the excipients employed and the techniques of obtaining the form dosage and the physiological ones of the gastrointestinal tract (GI tract), as for example, the pH of the liquid of the GI tract, gastric emptying time, intestinal motility, among others. Thus, assessment of dosage forms transit in GI tract after its administration allows a better understanding of the factors that may affect the drug release / dissolution steps in vivo. Among the techniques used for this purpose, the following stand out: scintigraphy and biomagnetic methods. Alternating Current Biosensiometry (ACB) is a biomagnetic method that has shown promise for this type of study, since it is non-invasive, portable, free of ionizing radiation, and because of its accuracy and versatility. In view of the above, the aim of this work was to develop and characterize a sustained release system containing nimesulide (study drug) and magnetic marker (ferrite) under the in vitro biopharmaceutical aspect, aiming to obtain a tool to evaluate the GI tract transit through means of biomagnetic technique. For this, four formulations of extended release tablets containing nimesulide, ferrite and different concentrations of hydroxypropylmethylcellulose (HPMC): NF1 (30% HPMC) were developed; NF2 (23% HPMC); NF3 (17% HPMC) and NF4 (10% HPMC). These were evaluated for dissolution behavior by apparatus 4, assays and kinetics and dissolution efficiency (ED%). Subsequently, biomagnetic studies, in vitro and in vivo, were conducted using the ACB technique for the selected formulation. The results showed that the formulations developed showed different percentages of dissolution as a function of the different concentrations of HPMC (NF1 = 13.2%, NF2 = 40.1%, NF3 = 72.5% and NF4 = 91.5%). The NF4 formulation, with a lower concentration of HPMC, was chosen for the ACB studies as a function of ED% results (54,3%) and because of the behavior of a sustained release formulation. In relation to the in vitro ACB results, the NF4 formulation (10% HPMC) showed an increase in magnetic area independently of the pH of the medium, suggesting that the HPMC hydration / swelling is independent of pH. In relation to intestinal transit evaluation (in vivo study) the following data were obtained: Mean Time of Gastric Residency (TTR) - 89 minutes; Mean Time of Orocecal Transit (OCTT) - 313 minutes and Mean Time of lntestinal Transit (TTI) - 224 minutes. ACB data in vivo showed that the increase in magnetic area reached a plateau in about 80 minutes after administration of the NF4 formulation. Comparison of in vitro ACB and ACB data in vivo, related to gastrointestinal transit, indicates that the NF4 formulation, after showing the swelling apex, was able to maintain its permanent structure throughout the GI tract, thus favoring the modulated release of the drug. The obtained results demonstrated that the developed formulation was efficient to evaluate and characterize the transit in the GI tract by means of the ACB technique and allowed a prediction of the behavior of the drug in relation to the solubility in each portion of the GI tract, thus providing a suitable tool for evaluation of the GI tract transit and the development of sustained release formulation.
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Rusczak, Jean Ricardo. "Desenvolvimento de um instrumento de análise de campos magnéticos." Universidade do Estado de Santa Catarina, 2013. http://tede.udesc.br/handle/handle/1868.
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This paper presents the study and development of a system for measuring magnetic field through search coils. The system consists of a magnetic shield, two Helmholtz coils to generate a magnetic field, inductive interchangeable sensors and a set of electronic boards which were used to evaluate the efficiency of the whole assembly by amplifying the sinals generated by the sensors and with a data acquisition system with LabVIEW. Several designs were developed in order to achieve the project objectives of B measures the range nT in a frequency range of 10 Hz to 10 kHz. Two types of input amplifiers were studied, one being based on the output voltage of the coils and another based on the magnetic flux passing through the coil. The instrumentation amplifier has a gain of 357,500 V / V and the transimpedance amplifier configuration has a gain of 47 000 V/I. The frequency performance is achieved in the range between 100 Hz to 10 kHz where is possible to estimate fields estimated 1 nT. The work includes the study of different materials for magnetic cores to allow miniaturization of the sensors.
Este trabalho apresenta o estudo e desenvolvimento de um sistema de medição de campo magnético através de ponteiras indutivas. O sistema é composto por uma blindagem magnética, duas bobinas de Helmholtz para a geração de campo magnético, sensores indutivos intercambiáveis e um conjunto de placas eletrônicas que serviram para avaliar a eficiência de toda a montagem ao amplificar os sinais e fazer a aquisição de dados com interface em LabVIEW. Foram desenvolvidas diversas formas construtivas a fim de se atingir os objetivos de projeto medidas na faixa de nT entre 10 Hz e 10 kHz. Dois tipos de amplificadores de entrada foram estudados, um sendo baseado na tensão de saída das espiras e outro no fluxo que passa pelas espiras. O amplificador de instrumentação possui um ganho de 357500 V/V e a configuração de fluxo possui um ganho 47000 I/V. A resposta em frequência apresentou uma performance aceitável entre 100Hz e 10 kHz onde possibilitou a leitura de campos estimados de 1 nT. Foram estudados, também, diferentes materiais para núcleos e que permitem a miniaturização dos sensores.
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GONÇALVES, Carlos Geraldo Barreto. "Efeitos do campo magnético artificial sobre o Camarão lLitopenaeus vannamei (Penaeidae) e sobre as capturas com covos de peixes e crustáceos no litoral sul de Pernambuco." Universidade Federal de Pernambuco, 2014. https://repositorio.ufpe.br/handle/123456789/18861.
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O campo magnético é uma fonte acessível de informação direcional passível de ser utilizada pelos seres vivos para orientação e navegação. Animais como mamíferos, aves, peixes, répteis marinhos, anfíbios, moluscos, insetos e crustáceos são sensíveis ao campo geomagnético. O presente estudo enfocou uma avaliação do efeito do campo magnético sobre peixes e crustáceos marinhos em condições naturais (área costeira) e sobre camarões Litopennaeus vannamei em condições controladas (laboratório). Os experimentos com peixes e crustáceos em condições naturais consistiram de sete a oito pescarias independentes, empregando-se armadilhas tipo covo distribuídos em cinco grupos de três a quatro unidades. Magnetos permanentes de 2000 Gauss em um raio de 2m foram fixados próximos à abertura de seis dos dezesete covos empregados. Ao final de cada pescaria os peixes e crustáceos capturados em cada covo foram identificados e contabilizados. Os níveis de capturas de peixes e crustáceos foram significativamente mais elevados nos covos com magneto. Dezessete espécies de crustáceos estiveram presentes nas capturas com os covos, dentre as quais as duas espécies mais frequentes foram Coryrhynchus riisei e Stenorhynchus seticornis. Trinta e duas espécies de peixes ocorreram nas capturas com os covos, com a espécie Haemulon aurolineatum (Xira branca) apresentando uma frequência de ocorrência uma a duas ordens de magnitude superior as demais espécies capturadas, principalmente nos covos com magneto. Ante este resultado, otólitos e tecidos da linha lateral, mancha ocelar, narina e área abdominal (controle) foram extraídos de cinco indivíduos jovens e de cinco indivíduos adultos de H. aurolineatum para investigar a presença de material magnético nessas estruturas. As amostras foram coletadas de indivíduos recém-capturados, secas em estufa e submetidas a medidas de ressonância ferromagnética (RFM) com uso de um espectrômetro Bruker ESP300E. Os espectros obtidos indicaram presença de material magnético nos otólitos, narinas e mancha ocelar e ausência de material magnético nos tecidos da área abdominal de todos os espécimes analisados. Nas amostras da linha lateral, a presença de material magnético pareceu estar relacionada ao desenvolvimento ontogenético, tendo sido detectado principalmente em espécimes adultos. Os experimentos em condições controladas foram realizados com camarões Litopenaeus vannamei considerando-se sexos e fases do seu ciclo ontogenético (machos e fêmeas adultos; machos e fêmeas juvenis e pós-larvas). Um par de bobinas circulares na configuração de Helmholtz, conectada a uma fonte regulável, foi empregado para a geração de diferentes intensidades (0, 25, 30, 35 e 40 μT) de campo magnético artificial uniforme. Os testes foram realizados de forma acumulativa e não acumulativa. No primeiro caso, um mesmo grupo de 15 camarões foi sequencialmente submetido aos cinco níveis de intensidade de campo magnético, com um intervalo de 24h entre exposições. No segundo caso, empregando- se novos grupos de 15 camarões para cada nível de exposição. Todos os testes foram realizados em triplicata. Os resultados evidenciaram a redução da atividade do L. vannamei quando expostos a campos de 35μT e 40 μT e sua paralisia total a campo de 40μT, assim como a preferência na ocupação do polo sul por fêmeas e machos adultos e juvenis e do polo norte por pós-larvas.
The magnetic field is a handy source of directional information that can be used by living things for orientation and navigation. Animals such as mammals, birds, fishes, marine reptiles, amphibians, molluscs, insects and crustaceans are sensitive to the geomagnetic field. The present study focused on an evaluation of the response of marine fishes and shellfishes subjected to an artificial magnetic field under natural conditions (coastal area) and under controlled conditions (laboratory). The experiments with fishes and crustaceans in natural conditions consisted of seven to eight independent fisheries employing creels traps distributed into five groups of three to four units. Permanent magnets of 2000 Gauss in a 2m radius were tied next to the opening of six of the seventeen creels employees. At the end of each fishery, fish and crustaceans caught in each trap were identified and accounted for. The levels of catches of fish and crustaceans were significantly higher in creels with magnet. Seventeen species of crustaceans were present in the catches with the creels, among which the two species most frequently were Coryrhynchus riisei and Stenorhynchus seticorni. Thirty-two species of fish were present in the catchs with the creels. The frequence of occurrence of the speciie Haemulon aurolineatum (Tomtate grunt) was one to two orders of magnitude higher than the other species caught, mainly in creels with magneto. Given this results, Otoliths and tissues of the lateral line, ocelar spot, nostril and abdomen (control) were extracted from five young individuals and five adult individuals of H. aurolineatum to investigate the presence of magnetic material in these structures. The samples were collected from newly captured individuals, oven-dried and subjected to measures of ferromagnetic resonance (RFM) using a Bruker ESP300E spectrometer. The spectra obtained indicated presence of magnetic material in otoliths, nostrils and ocelar spot and absence of magnetic material in the tissues of the abdominal area of all specimens examined. In the samples of the lateral line, the presence of magnetic material seems to be related to the ontogenetic development, having been detected mainly among adult specimens. The experiments under controlled conditions were performed with the shrimp Litopenaeus vannamei considering different sexes and stages of their ontogenetic cycle (adult males and females; juvenils males and females and post-larvae). A pair of circular coils in Helmholtz configuration, connected to an adjustable power source was used to generate different intensities (0, 25, 30, 35 and 40 μT) of uniform artificial magnetic field. The tests were carried out in accumulative and non accumulative manners. In the first case, a group of 15 shrimps was sequentially exposed to the five levels of magnetic field intensity, with a 24 hours interval between exposures. In the second case, using new groups of 15 shrimps for each level of exposure. All tests were performed in triplicate. The results showed a reduction in activity of L. vannamei when exposed to fields of 35 μT and higher and their total paralysis to levels of 40 μT, as well as the preference in the occupation of the South Pole by females and males juvenils and adults and of the North Pole by post-lavae.
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Popescu, Elena-Anda. "Source characterization using linear transformations of multichannel biomagnetic recordings." Thesis, 2008. http://hdl.handle.net/10889/8395.
Full textAbstract:
The biomagnetic measurements offer completely non-invasive and non-contact multichannel recordings with millisecond temporal resolution that provide the direct assessment of the functional dynamics of the brain, via magnetoencephalography (MEG), and heart, via magnetocardiography (MCG). Dense-array biomagnetometers have been recently designed for the investigation of the neurophysiological development of the fetus in utero. Fetal MCG offers accurate recordings of the fetal cardiac activity that allow to examine the effects of different maternal factors (such as smoking, exercise, fatty-acids diet supplements) on the fetal neurophysiological development using measures of heart rate and heart rate variability, and high-resolution measurement of the cardiac time intervals. However, the extraction of the fetal MCG signal relies on the identification and elimination of other signal contributions associated with the maternal cardiac activity or specific fetal behavioral patterns, such as fetal sucking and hiccup activity.
The results of the present thesis demonstrate the potential of the linear transformations to generate data representations that enable straightforward and effective extraction and characterization of the biomagnetic signal components, and the elimination of the interference. The independent component analysis has been proven as an efficient signal separation and filtering technique for fetal biomagnetic recordings. ICA has been shown to provide adequate interference elimination of the maternal and fetal cardiac activity for the separation of the signal associated with distinct fetal behavioral patterns. Specifically, ICA has been applied to the extraction of the non-nutritive sucking pattern in the fetus. The recorded biomagnetic signal was characterized by the distinctive rhythmic pattern of bursts documented in the fetus using Doppler ultrasonography. The signal characteristics were consistent with the pacifier-induced non-nutritive sucking recorded in the infant using measurements of the sucking pressure variation and electromyography (EMG)recordings. Additionally, the measurements in fetuses have been confirmed by the biomagnetic recordings of the pacifier-induced non-nutritive sucking in infants. Correspondingly, the signal pattern associated with the fetal hiccup activity has been recorded and characterized using biomagnetic measurements in the fetus. The signal waveform was consistent with the adult EMG data of the diaphragm motor response to electrical or magnetic stimulation of the phrenic nerve. Additionally, the simultaneous recording of the fetal cardiac activity allows the estimation of the fetal heart rate signal. Thus, it has been possible to assess the interaction between the fetal behavior and the fetal heart rhythm.
Although the linear transformations of the biomagnetic data, such as the signal subspace separation, beamforming or independent component analysis methods, do not provide direct information on the location of the sources, they generate data representations that enable the separation of the distinct signal components. The signal subspace separation method based on irreducible tensor representation approach may potentially allow to segregate and remove the contribution of the external interference sources, e.g. an active ultrasound device for real-time monitoring during fetal biomagnetic recording. The preliminary assessment indicates the ability of the irreducible tensor representation technique to provide an effective data transformation for the compensation of fetal movement during the recording that affects the accuracy of the averaged fetal cardiac signal. Additionally, the modified beamformers with suppression region that integrate a priori anatomical information in order to perform an adaptive suppression of the interferers may be proven more efficient for accurate signal estimation of the fetal spontaneous brain activity, and auditory and visual evoked responses.Σύγχρονες μή-επεμβατικές τεχνικές καταγραφής πολυκαναλικού σήματος προσφέρουν, χωρίς άμεση επαφή, βιομαγνητικές μετρήσεις με υψηλότατη χρονική ανάλυση και επιτρέπουν την άμεση εκτίμηση των δυναμικών λειτουργιών του εγκεφάλου και της καρδιάς, μέσω του μαγνητοεγκεφαλογραφήματος (ΜΕΓ) και του μαγνητοκαρδιογραφήματος (ΜΚΓ) αντίστοιχα. Η χρήση πυκνών διατάξεων μαγνητομέτρων στην ευρύτερη κοιλιακή χώρα για την καταγραφή μαγνητικών πεδίων από το έμβρυο επιτρέπει τη μελέτη της νευροφυσιολογικής ανάπτυξης του εμβρύου καθ’ όλη τη διάρκεια της κύησης. Ειδικά το εμβρυϊκό ΜΚΓ επιτρέπει την εκτίμηση της καρδιακής λειτουργίας και την εξέταση της επίδρασης διαφορετικών παραμέτρων όπως το κάπνισμα της μητέρας, η άσκησή της και η διατροφή της, χρησιμοποιώντας παράγωγα χαρακτηριστικά του εμβρυϊκού καρδιακού σήματος (π.χ. ο καρδιακός ρυθμός και η μεταβλητότητά του). Η ανάκτηση του συγκεκριμένου σήματος προϋποθέτει τον εντοπισμό και εξουδετέρωση παρασιτικών σημάτων που σχετίζονται με το καρδιακή δραστηριότητα της μητέρας ή συγκεκριμένες συμπεριφορές του εμβρύου όπως η αναρρόφηση και η κατάποση. Τα αποτελέσματα της παρούσης διατριβής επιδεικνύουν τη δυνατότητα των γραμμικών μετασχηματισμών για αναπαραστάσεις που επιτρέπουν την άμεση και αποτελεσματική εκμαίευση και περιγραφή των σημαντικών συνιστωσών του βιομαγνητικού σήματος καθώς και την αναίρεση των ανεπιθύμητων παρεμβολών. Η ανάλυση σε ανεξάρτητες συνιστώσες (ΑΑΣ) κρίθηκε ιδιαίτερα αποδοτική στην ανάδειξη της χρήσιμης πληροφορίας από εμβρυϊκές βιομαγνητικές καταγραφές και συνέβαλε στην εξουδετέρωση των σημάτων καρδιακής δραστηριότητας του εμβρύου και της μητέρας. Η κατάλληλη χρησιμοποίησή της ουσιαστικά εξασφάλισε το διαχωρισμό του σήματος που σχετίζεται με συγκεκριμένα πρότυπα συμπεριφοράς του εμβρύου. Ειδικότερα επέτρεψε την παρακολούθηση της συμπεριφοράς αυτόνομου θηλασμού (που είναιασυσχέτιστη με την διατροφική διαδικασία). Το ανακτημένο σήμα χαρακτηρίζεται από ιδιαίτερα ρυθμική δραστηριότητα που περιλαμβάνει ώσεις γνωστές και από τις απεικονίσεις μέσω του υπερηχογραφήματος Doppler. H συμπεριφορά που το σήμα αντικατοπτρίζει είναι εντελώς συμβατή με αυτή που εμφανίζεται αυτόματα στα νεογνά με την προσαρμογή πιπίλας στη στοματική τους κοιλότητα, και η οποία συνήθως μελετάται μέσω των μεταβολών πίεσης στο σχετικό ηλεκτρομυογράφημα. Η συγκεκριμένη συσχέτιση επιβεβαιώθηκε -και πειραματικά- με την καταγραφή βιομαγνητικών πεδίων από νεογνά κατά τη διάρκεια αυθόρμητου θηλασμού (δηλ. με πιπίλα). Αντίστοιχα, το ανακτημένο σήμα που σχετίζεται με τον εμβρυϊκό λόξυγκα βρίσκεται σε απόλυτη συνέπεια με τις κυματομορφές της ηλεκτρομυογραφικής απόκρισης από το διάφραγμα ενηλίκων σε ηλεκτρική ή μαγνητική διέγερση του φρενικού νεύρου. Επίσης η εξαγωγή του εμβρυϊκού καρδιακού σήματος επέτρεψε τον ακριβή υπολογισμό των μεταβολών του αντίστοιχου ρυθμού και τον συσχετισμό τους με τα διάφορα πρότυπα συμπεριφορά (θηλασμό, λόξυγκα κτλ.). Παρόλο που γραμμικοί μετασχηματισμοί των βιομαγνητικών δεδομένων (όπως τεχνικές υποχώρων, χωρικά φίλτρα επιλεκτικής κατεύθυνσης και ανάλυση σε ανεξάρτητες συνιστώσες) δεν παρέχουν άμεση πληροφορία για τον εντοπισμό των πηγών του σήματος, προσφέρουν αναπαραστάσεις των δεδομένων όπου η συνεισφορά των επιμέρους πηγών είναι καλά διαχωρισμένη. Η τεχνική διαχωρισμού υποχώρων (βασισμένη στην προσέγγιση αναπαράστασης μέσω μή αναγώγιμου τανυστή) δυνητικά μπορεί να επιτρέψει τη διάκριση και απομάκρυνση εξωγενών σημάτων όπως αυτά που προέρχονται από τις παρακείμενες συσκευές υπερηχογραφήματος που χρησιμοποιούνται για την παρακολούθηση του εμβρύου σε πραγματικό χρόνο. Η προκαταρκτική αξιολόγηση έδειξε την δυνατότητα της τεχνικής αυτής να μετασχηματίζει τα δεδομένα με τρόπο που να βελτιώνει την ακρίβεια του εμβρυϊκού συμψηφιστικού καρδιογραφήματος (κυρίως χάριν στην αντιστάθμιση της αναπόφευκτης μετακίνησης του εμβρύου σε σχέση με του αισθητήρες). Επιπρόσθετα η εναρμόνιση της τεχνικής αυτής με την ανατομία του προβλήματος ενέχει την δυνατότητα προσαρμοστικής επεξεργασίας σήματος και αναμένεται να συμβάλει στην εκτίμηση της αυθόρμητης εγκεφαλικής δραστηριότητας του εμβρύου καθώς και των αντίστοιχων εγκεφαλικών αποκρίσεων σε εξωτερικά ερεθίσματα.
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Bai, Hong-Yi, and 白宏益. "Detection of Biomagnetic Source by the Method of Maximum Entropy." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/42333064575228684044.
Full textAbstract:
碩士國立中興大學
物理學系
91
This thesis applied a novel approach to the detection of active sources in the cortex from magnetic field measurements on the scalp in magnetoencephalograph (MEG). In order to get the neurons’s activation, we have to solve an ill-posed inverse problem. Our approach to the solution is the framework of Maximum Entropy on the Mean. A reference probability measure on the random variables is our means of regularizing of the singular nature of the problem. The variables are the intensity of current sources on the cortical region which include all available prior information that help in the regularization. We also introduce a hidden Markov random variable as part of the prior information. The Maximum Entropy method is used again within this framework. Finally, we demonstrate how the method is applied in a practical detection of cerebral activity by analyzing simulated MEG data.
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Joseph, Jon P. "Biomagnetism and the biomagnetism laboratory." 1988. http://catalog.hathitrust.org/api/volumes/oclc/19568895.html.
Full textAbstract:
Thesis (Ph. D.)--University of Wisconsin--Madison, 1988.Vita. Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 140-145).
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Chiu-Hsien, Wu. "Fabrication and Characterization of High Sensitivity SQUID Magnetometers for Biomagnetism." 2005. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0001-2707200502175900.
Full text
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Wu, Chiu-Hsien, and 吳秋賢. "Fabrication and Characterization of High Sensitivity SQUID Magnetometers for Biomagnetism." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/64241442827228733336.
Full textAbstract:
博士國立臺灣大學
物理研究所
93
The fabrication and characterization of high-Tc sensitivity SQUID magnetometers for biomagnetism at 77 K were investigated. To pursue the high reproducibility and quality step edge for high-Tc SQUIDs, we have developed two-step procedures of fabricating very good step-edge substrates. We have characterized high-Tc step-edge SQUIDs connected in series. The flux-to-voltage transfer function increase with the number of SQUIDs. The flux noise, SΦ of the serial SQUID arrays scale as 1/N1/2. Second, we fabricated a serial low-noise direct-current superconducting quantum interference device (SQUID) magnetometer on a 10 mm × 10 mm SrTiO3 (100) bicrystal substrate. This field sensitivity around 30–80 fT/Hz1/2 has been obtained at 77 K in the white noise region. The latter noise has been avoided by optimizing the geometry of the pickup coil as well as by using the so-called flux dam. As a result, the 1/f noise of SQUIDs has been much improved. Finally, using atomic Force microscope (AFM) and scanning electric microscopy (SEM), we observe an inhomogeneous distribution and microstructural defects on YBCO grain-boundary Josephson junctions. SEM images show that these defects cause the grain boundary of YBCO thin film grown on the bicrystal to a few submicron depth of the groove in film. The existence of these defects is expected to affect the superconducting current and the motion of the magnetic flux in the films and hence generate noise in the devices.