Modulated Gradients
Mostrando 1-12 de 16 artigos, teses e dissertações.
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1. Assessment of radiotherapic treatments with thermoluminescent dosimetry / Verificação de tratamentos radioterápicos diversos com dosimetria termoluminescente
The last decades noticed a massive improvement in radiotherapy techniques and the use of segmented beams produced by multileaf collimators. However, the dose radiation therapy planning systems (TPS) in use are characterized by the restriction of access to the calculation algorithms. The aim of this work was to compare dose values measured in an anthropomorph
Publicado em: 2007
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2. Descrição analítica da magnetização induzida pela metodologia GMAX / Analytical description of the magnetization induced by the GMAX sequence
A metodologia GMAX, (Gradient-Modulated Adiabatic Excitation), caracteriza-se pelo uso de pulsos adiabáticos para localização de volumes em espectroscopia e seleção de fatias em MRI. A sua utilidade surge do interessante perfil de inversão da magnetização transversal induzido ao longo da amostra. Entretanto, a interpretação desse comportamento tem
Publicado em: 2003
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3. “Shim pulses” for NMR spectroscopy and imaging
A way to use adiabatic radiofrequency pulses and modulated magnetic-field gradient pulses, together constituting a “shim pulse,” for NMR spectroscopy and imaging is demonstrated. These pulses capitalize on phase shifts derived from probe gradient coils to compensate for nonlinear intrinsic main magnetic field homogeneity for spectroscopy, as well as for
National Academy of Sciences.
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4. Modulation by applied electric fields of Purkinje and stellate cell activity in the isolated turtle cerebellum.
Quasi steady-state electric fields were applied across the isolated turtle cerebellum to study the relationship between applied field, neuronal morphology and the modulation of the neuronal spike firing pattern. Spiking elements were identified electrophysiologically using extracellular recording methods and by subsequent horseradish peroxidase injection, wh
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5. Convexity of the Photosynthetic Light-Response Curve in Relation to Intensity and Direction of Light during Growth.
Photosynthesis in the intermediate light range is most efficient when the convexity of the photosynthetic light-response curve is high. Factors determining the convexity were examined for intact leaves using Salix sp. and for a plant cell culture using the green microalga Coccomyxa sp. It was found that the leaf had lower convexity than diluted plant cells b
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6. Ionic factors in release of 45Ca2+ from chicken cerebral tissue by electromagnetic fields.
Electrical stimulation with radiofrequency fields amplitude-modulated at brain wave frequencies increased 45Ca2+ efflux from isolated chicken cerebral tissue. The response was not sensitive to variations of the calcium concentration (0-4.16 mM) in the bathing solution but was enhanced by addition of H+ (0.108 mM HCl) and inhibited in the absence of normal bi
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7. Isolation and characterization of minichromosome particles that contain a glucocorticoid-modulated promoter.
A procedure for the enrichment of minichromosomes, composed of bovine papilloma virus and the long terminal repeat element of the mouse mammary tumor virus (MTV), from isolated nuclei is described. Up to 60% of the minichromosomes were extracted as nucleoprotein particles. These particles sediment in sucrose gradients as 160S complexes. Hormone-labeled gluco
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8. Two Seven-Transmembrane Domain MILDEW RESISTANCE LOCUS O Proteins Cofunction in Arabidopsis Root Thigmomorphogenesis[C][W]
Directional root expansion is governed by nutrient gradients, positive gravitropism and hydrotropism, negative phototropism and thigmotropism, as well as endogenous oscillations in the growth trajectory (circumnutation). Null mutations in phylogenetically related Arabidopsis thaliana genes MILDEW RESISTANCE LOCUS O 4 (MLO4) and MLO11, encoding heptahelical,
American Society of Plant Biologists.
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9. Growth factor signaling in lung morphogenetic centers: automaticity, stereotypy and symmetry
Lung morphogenesis is stereotypic, both for lobation and for the first several generations of airways, implying mechanistic control by a well conserved, genetically hardwired developmental program. This program is not only directed by transcriptional factors and peptide growth factor signaling, but also co-opts and is modulated by physical forces. Peptide gr
BioMed Central.
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10. Differential premature termination of transcription as a proposed mechanism for the regulation of coronavirus gene expression.
We propose that the different subgenomic mRNA levels of coronaviruses are controlled through differential premature termination of transcription, and are modulated by the relative strength of transcriptional initiation/blockage events. We present the complete set of sequences covering the leader encoding and intergenic regions of the MHV-A59 strain. A comput
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11. Nuclear Ca2+ concentration measured with specifically targeted recombinant aequorin.
Activation of nuclear transcription factors, breakdown of nuclear envelope and apoptosis represent a group of nuclear events thought to be modulated by changes in nucleoplasmic Ca2+ concentration, [Ca2+]n. Direct evidence for, or against, this possibility has been, however, difficult to obtain because measurements of [Ca2+]n are hampered by major technical p
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12. Aspergillus asexual reproduction and sexual reproduction are differentially affected by transcriptional and translational mechanisms regulating stunted gene expression.
The Stunted protein (StuAp) is a member of a family of transcription factors that regulate fungal development and cell cycle progression. Regulated stuA gene expression is required for correct cell pattern formation during asexual reproduction (conidiation) and for initiation of the sexual reproductive cycle in Aspergillus nidulans. Transcriptional initiatio