Rf Coil
Mostrando 1-12 de 14 artigos, teses e dissertações.
-
1. Desenvolvimento de bobinas de RF transmissoras e receptoras do tipo phased arrays para experimentos de imagens por ressonância magnética em ratos / Development of RF transmitter coils and receivers NMR phased arrays for magnetic resonance imaging experiments on rats
Experimentos de Imagens por Ressonância Magnética (IRM) em pequenos animais, assim como em humanos, exigem um conjunto especifico de bobinas de Radiofrequência (RF) para maximizar ambos a homogeneidade de campo durante a transmissão e a Relação Sinal Ruído (RSR) durante a recepção. As geometrias mais comuns de bobinas transmissoras utilizadas em sis
Publicado em: 2011
-
2. Shielded transceiver RF coil array for simultaneous PET-MRI
The complementary information provided by combined MRI-PET modalities promises to facilitate metabolic investigations of complex physiological processes. We developed a radio frequency (RF) coil array that can operate in close proximity (2-mm radial distance) to a miniaturized PET camera insert for simultaneous PET-MRI of a rat brain at high magnetic fields
Brazilian Journal of Physics. Publicado em: 2008-06
-
3. Cerebral perfusion quantification using arterial spin labeling: applications in vascular territories measurement and functional imaging / Quantificação da perfusão sanguínea cerebral utilizando arterial spin labeling: aplicações em medidas de territórios vasculares e em imagens funcionais
Arterial spin labeling techniques allow to obtain quantitative maps of perfusion non-invasively. Along with other MRI techniques, it has proven useful for diagnosis of a variety of cerebrovascular diseases. Amongst the available basic implementations, the continuous approach employing a dedicated labeling RF coil has the advantages of presenting high signal-
Publicado em: 2008
-
4. Determination fo the configuration of excited Alfvén waves in tokamak TCABR / Determinação da configuração de ondas de alfvén excitadas no tokamak TCABR
In order to enhance the efficiency of the TCABRs Alfvén waves heating system, called AWES - Alfvén Waves Excitement System a diagnostics for determining the radio-frequency power applied to the plasma and a processing circuit for the magnetic coil system was built, characterized, installed and put into operation. The RF diagnostics system was designed to d
Publicado em: 2007
-
5. Transdutores de RF para experimento de imagens em pequenos animais / RF coils for MRI experiments on small animals
O objetivo deste projeto é o desenvolvimento de transdutores de RF tipo gaiola (birdcage coil) e sela (saddle coil), com desenho especial inovador, que mantém elementos com comprimento elétrico constante, para um campo magnético de 2 Tesla. Este transdutor deve permitir o estudo e também o desenvolvimento de novas metodologias em imagens e espectroscopi
Publicado em: 2006
-
6. "Development and clinical applications of a high performance radio-frequency/gradient coil integrated system for Magnetic Resonance Imaging in 0.5 Tesla" / "Desenvolvimento e aplicações clínicas de um sistema integrado transdutor/bobinas de gradientes de alto desempenho para obtenção de imagens por ressonância magnética em 0.5 TESLA"
Este trabalho descreve o desenvolvimento de um sistema integrado transdutor/bobinas de gradientes de alto desempenho para Imagens por Ressonância Magnética. Este sistema é composto por um transdutor de radiofreqüência tipo sela e um conjunto de 3 bobinas locais assimétricas. No desenho do transdutor foram otimizados os parâmetros: relação sinal ruí
Publicado em: 2005
-
7. Mri coil design and receiver system for ultra low field magnetic resonance imaging / Projeto de transdutores e otimização do sistema de recepção do tomógrafo de RMN de campo magnético ultrabaixo
O objetivo deste trabalho foi melhorar a relação sinal-ruído de um sistema de imagens por ressonância magnética nuclear (TORM 005), através do desenvolvimento de bobinas de recepção mais eficientes, de circuitos de sintonia balanceados, circuitos de desacoplamento de potência para as bobinas receptoras e da melhoria do ambiente eletromagnético no q
Publicado em: 1995
-
8. Aquecimento do plasma por radio frequencia na maquina linear lisa
We show in this work the characteristics of an experimental device assembled in the Instituto de Física, Universidade Federal Flurninense (Linear Mirror Type Machine LISA) to produce Helium plasma by RF and to study its behavior when confined by a magnetic field with mirrors. The plasma was produced by a micro-wave generator of, fRF = 2.45 GHz, PRF = 800 Wa
Publicado em: 1986
-
9. Radiofrequency hyperthermia with successive monitoring of its effects on tumors using NMR spectroscopy.
Radiofrequency (rf) hyperthermia was generated on rat glioma inoculated s.c. in CD Fisher rats by applying the rf pulse using the surface coil in the NMR spectrometer, and the effect was monitored successively in the same spectrometer by measuring 31P NMR spectra and 1H NMR images. In the 31P NMR spectrum at the preirradiation stage, nucleoside triphosphate
-
10. Replication of Bacteriophage Ribonucleic Acid: Analysis of the Ultrastructure of the Replicative Form and the Replicative Intermediate of Bacteriophage R17
A detailed qualitative and quantitative comparison was made of the ultrastructure of single-stranded ribonucleic acid (RNA) from bacteriophage R17 and double-stranded replicative form (RF) and replicative intermediate (RI) from cells infected with this bacteriophage. The nucleic acids were prepared for electron microscopy by the protein monolayer spreading t
-
11. Termination of translation in bacteria may be modulated via specific interaction between peptide chain release factor 2 and the last peptidyl-tRNA(Ser/Phe).
The 5' context of 671 Escherichia coli stop codons UGA and UAA has been compared with the context of stop-like codons (UAC, UAU and CAA for UAA; UGG, UGC, UGU and CGA for UGA). We have observed highly significant deviations from the expected nucleotide distribution: adenine is over-represented whereas pyrimidines are under-represented in position -2 upstream
-
12. Introduction of short-range restrictions in a protein-folding algorithm involving a long-range geometrical restriction and short-, medium-, and long-range interactions
A protein-folding algorithm, based on short-range and geometrical long-range restrictions, is applied to bovine pancreatic trypsin inhibitor (BPTI). These restrictions are used to define a starting conformation, SI, by means of a space-filling model of the protein, whose energy is then minimized. The long-range restriction is the imposition of the native spa