Search results for "Positron"

showing 10 items of 1346 documents

Effect of Vacancies on Positron Annihilation and Hyperfine Interactions in Fe-Al Alloys - <i>Ab Initio</i> Study

2012

Vacancies occupying different sub-lattices of D03 structure of Fe3Al alloy were investigated by the full potential linearized augmented plane wave method. The calculations basing on the super-cell approach have been performed for the vacancy concentrations of 1.6 and 3 at.%. For both concentrations the sub-lattice preference for vacancy location was determined. The dependence of vacancy formation energy on magnetic state of structure has been found. The positron lifetimes for the annihilation in the bulk (Fe3Al) and in vacancies have been investigated basing on the ab initio results for the electron density. The effect of vacancies on spin magnetic moment and hy-perfine parameters of Fe ato…

Electron densityMaterials scienceAnnihilationCondensed matter physicsAlloyAb initioengineering.materialCondensed Matter PhysicsAtomic and Molecular Physics and OpticsSpin magnetic momentCondensed Matter::Materials SciencePositronVacancy defectPhysics::Atomic and Molecular ClustersengineeringGeneral Materials ScienceHyperfine structureSolid State Phenomena
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A case of disseminated BCG infection in a daughter of Italian immigrants in Switzerland

2022

Bacillus Calmette-Guérin (BCG) is a vaccine against tuberculosis and contains a live, attenuated strain of Mycobacterium bovis as its essential constituent. Being a live, attenuated strain with potential pathogenicity, BCG can cause different complications, both near the inoculation site and through blood dissemination, especially in patients with immunodeficiency. IFN-γR1 deficiency is an autosomal recessively inherited immunodeficiency characterized by predisposition to infections with intracellular pathogens, in particular mycobacteria.
 We report a rare case of chronic osteomyelitis lasting 30 years due to BCG in a woman with IFN-γR1 deficiency who had previous clinical history of …

Emigrants and ImmigrantsDisseminated BCG infectionEmigrants and ImmigrantGeneral MedicinedeficiencyMicrobiologyNuclear FamilyInfectious DiseasesIFN-γR1VirologyPositron Emission Tomography Computed TomographyBCG VaccineHumansTuberculosisParasitologyFemaleChildTuberculosis.SwitzerlandHuman
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Observation of e + e − → ηψ(2S) at center-of-mass energies from 4.236 to 4.600 GeV

2021

Journal of high energy physics 2021(10), 177 (2021). doi:10.1007/JHEP10(2021)177

ExoticsNuclear and High Energy Physicsmeasured [channel cross section]e+-e− ExperimentsQuarkoniumannihilation [electron positron]QC770-798electron positron: annihilationetaParticle and resonance productionMeasure (mathematics)530Standard deviationNONuclear physicsSubatomär fysikCross section (physics)e+-e��� Experimentsenergy dependence: measured [cross section]Astronomi astrofysik och kosmologiNuclear and particle physics. Atomic energy. RadioactivitySubatomic PhysicsAstronomy Astrophysics and Cosmologyddc:530e+-e− Experiments Exotics Particle and resonance production Quarkoniumpsi(3685)PhysicsBESe(+)-e(-) ExperimentsDetectorstatistical [error]electron positron --> eta psi(3685)e +-e − Experimentselectron positron: colliding beamsBeijing Stor4.236-4.600 GeV-cmsCollisionerror: statisticalYield (chemistry)e-e Experimentselectron positron --> eta psi(3685)colliding beams [electron positron]High Energy Physics::ExperimentCenter of masscross section: energy dependence: measuredchannel cross section: measuredStorage ringexperimental results
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Fast PET Scan Tumor Segmentation Using Superpixels, Principal Component Analysis and K-Means Clustering

2018

Positron Emission Tomography scan images are extensively used in radiotherapy planning, clinical diagnosis, assessment of growth and treatment of a tumor. These all rely on fidelity and speed of detection and delineation algorithm. Despite intensive research, segmentation remained a challenging problem due to the diverse image content, resolution, shape, and noise. This paper presents a fast positron emission tomography tumor segmentation method in which superpixels are extracted first from the input image. Principal component analysis is then applied on the superpixels and also on their average. Distance vector of each superpixel from the average is computed in principal components coordin…

FOS: Computer and information sciencespositron emission tomographyprincipal component analysisComputer scienceComputer Vision and Pattern Recognition (cs.CV)k-meansCoordinate systemComputer Science - Computer Vision and Pattern RecognitionFOS: Physical sciences02 engineering and technologyBenchmarkQuantitative Biology - Quantitative MethodsBiochemistry Genetics and Molecular Biology (miscellaneous)030218 nuclear medicine & medical imagingsuperpixels03 medical and health sciences0302 clinical medicineStructural Biology0202 electrical engineering electronic engineering information engineeringmedicineSegmentationComputer visionTissues and Organs (q-bio.TO)Cluster analysisQuantitative Methods (q-bio.QM)Pixelmedicine.diagnostic_testbusiness.industrysegmentationk-means clusteringQuantitative Biology - Tissues and OrgansPattern recognitionPhysics - Medical PhysicsPositron emission tomographyFOS: Biological sciencesPhysics - Data Analysis Statistics and ProbabilityPrincipal component analysis020201 artificial intelligence & image processingMedical Physics (physics.med-ph)Artificial intelligenceNoise (video)businessData Analysis Statistics and Probability (physics.data-an)BiotechnologyMethods and Protocols
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Artificial Intelligence Applications on Restaging [18F]FDG PET/CT in Metastatic Colorectal Cancer: A Preliminary Report of Morpho-Functional Radiomic…

2022

Featured Application Based on results defined in this study, new investigations might propose morpho-functional-based radiomics algorithms for risk stratification with possible impact on treatment management in colorectal cancer. The aim of this study was to investigate the application of [F-18]FDG PET/CT images-based textural features analysis to propose radiomics models able to early predict disease progression (PD) and survival outcome in metastatic colorectal cancer (MCC) patients after first adjuvant therapy. For this purpose, 52 MCC patients who underwent [F-18]FDGPET/CT during the disease restaging process after the first adjuvant therapy were analyzed. Follow-up data were recorded f…

Fluid Flow and Transfer ProcessescolonradiomicsProcess Chemistry and TechnologyGeneral Engineeringpositron emission tomography-computed tomographycancercolon; cancer; radiomics; artificial intelligence; positron emission tomography-computed tomography; nuclear medicineGeneral Materials Sciencenuclear medicineartificial intelligenceInstrumentationComputer Science Applications
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Evaluation of P-glycoprotein (abcb1a/b) modulation of [18F]fallypride in MicroPET imaging studies

2012

[(18)F]Fallypride ([(18)F]FP) is an important and routinely used D2/D3 antagonist for quantitative imaging of dopaminergic neurotransmission in vivo. Recently it was shown that the brain uptake of the structurally related [(11)C]raclopride is modulated by P-glycoprotein (P-gp), an important efflux transporter at the blood-brain barrier. The purpose of this study was to determine whether the brain uptake of [(18)F]FP is influenced by P-gp. For examination of this possible modulation microPET studies were performed in a rat and a mouse model. Hence, [(18)F]FP was applied to Sprague Dawley rats, half of them being treated with the P-gp inhibitor cyclosporine A (CsA). In a second experimental s…

Fluorine RadioisotopesATP Binding Cassette Transporter Subfamily BStandardized uptake valueStriatumPharmacologyRats Sprague-DawleyMiceCellular and Molecular NeuroscienceCerebellummedicineAnimalsEnzyme InhibitorsReceptorP-glycoproteinMice KnockoutPharmacologyRaclopridebiologyChemistryWild typeAntagonistBrainCorpus StriatumFallypridePositron-Emission TomographyBenzamidesCyclosporinebiology.proteinRadiopharmaceuticalsmedicine.drugNeuropharmacology
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Synthesis and evaluation of (S)-2-(2-[18F]fluoroethoxy)-4-([3-methyl-1-(2-piperidin-1-yl-phenyl)-butyl-carbamoyl]-methyl)-benzoic acid ([18F]repaglin…

2004

18F-labeled non-sulfonylurea hypoglycemic agent (S)-2-(2-[(18)F]fluoroethoxy)-4-((3-methyl-1-(2-piperidin-1-yl-phenyl)-butylcarbamoyl)-methyl)-benzoic acid ([(18)F]repaglinide), a derivative of the sulfonylurea-receptor (SUR) ligand repaglinide, was synthesized as a potential tracer for the non-invasive investigation of the sulfonylurea 1 receptor status of pancreatic beta-cells by positron emission tomography (PET) in the context of type 1 and type 2 diabetes. [(18)F]Repaglinide could be obtained in an overall radiochemical yield (RCY) of 20% after 135 min with a radiochemical purity higher than 98% applying the secondary labeling precursor 2-[(18)F]fluoroethyltosylate. Specific activity w…

Fluorine RadioisotopesCancer ResearchBiodistributionMetabolic Clearance RateReceptors DrugContext (language use)Sulfonylurea ReceptorsRats Sprague-DawleyIslets of Langerhanschemistry.chemical_compoundPiperidinesmedicineRadioligandAnimalsTissue DistributionRadiology Nuclear Medicine and imagingPotassium Channels Inwardly RectifyingBenzoic acidChemistryBiological activityLigand (biochemistry)RepaglinideRatsDissociation constantBiochemistryOrgan SpecificityRats Inbred LewIsotope LabelingPositron-Emission TomographyFeasibility StudiesMolecular MedicineATP-Binding Cassette TransportersCarbamatesMultidrug Resistance-Associated ProteinsRadiopharmaceuticalsNuclear chemistrymedicine.drugNuclear Medicine and Biology
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Improved automated synthesis of [18F]fluoroethylcholine as a radiotracer for cancer imaging.

2007

[(18)F]Fluoroethylcholine has been recently introduced as a promising (18)F-labelled analogue of [(11)C]choline which had been previously described as a tracer for metabolic cancer imaging with positron emission tomography (PET). Due to the practical advantages of using the longer-lived radioisotope (18)F (t(1/2)=110 min), offering the opportunity of a more widespread clinical application, we established a reliable, fully automated synthesis for its production using a modified, commercially available module. [(18)F]Fluoroethylcholine was prepared from N,N-dimethylaminoethanol by iodide catalyzed alkylation with 1-[(18)F]fluoro-2-tosylethane as alkylating agent, resulting in a total radioche…

Fluorine RadioisotopesClinical BiochemistryIodidePharmaceutical ScienceCancer imagingAlkylationBiochemistryChemical synthesisSensitivity and SpecificityCholineNeoplasmsDrug DiscoverymedicineMolecular BiologyChromatography High Pressure LiquidFluoroethylcholinechemistry.chemical_classificationmedicine.diagnostic_test18F-FluoroethylcholineMolecular StructureChemistryOrganic ChemistryRadiochemistryBiochemistryFully automatedPositron emission tomographyMolecular MedicineBioorganicmedicinal chemistry
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The DAT ligand [(18)F]PR17.MZ mirrors the in vivo pharmacokinetic profile of [(11)C]cocaine with significantly improved monoamine transporter selecti…

2010

Fluorine RadioisotopesContrast MediaPharmacologyLigandsBiochemistryRats Sprague-DawleyPharmacokineticsCocaineIn vivoDrug DiscoverymedicineAnimalsBiogenic MonoaminesCarbon RadioisotopesGeneral Pharmacology Toxicology and PharmaceuticsDopamine transporterPharmacologyDopamine Plasma Membrane Transport ProteinsMonoamine transporterbiologymedicine.diagnostic_testChemistryOrganic ChemistryLigand (biochemistry)RatsBiochemistryPositron emission tomographyPositron-Emission Tomographybiology.proteinMolecular MedicineRadiopharmaceuticalsSelectivityChemMedChem
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P-Glycoprotein Influence on the Brain Uptake of a 5-HT2A Ligand: [18F]MH.MZ

2010

<i>Background/Aims:</i> The serotonergic system, especially the 5-HT<sub>2A</sub> receptor, is involved in various diseases and conditions. We have recently developed a new [<sup>18</sup>F]-5-HT<sub>2A</sub> receptor ligand using an analogue, MDL 100907, as a basis for molecular imaging with positron emission tomography. This tracer, [<sup>18</sup>F]MH.MZ, has been shown to be an adequate tool to visualize the 5-HT<sub>2A</sub> receptors in vivo. However, [<sup>18</sup>F]altanserin, similar in chemical structure, is a substrate of efflux transporters, such as P-glycoprotein (P-gp), of the blood-brain barrier…

Fluorine RadioisotopesPharmacologyBiologySerotonergicBlood–brain barrierMicePiperidinesPharmacokineticsCerebellummedicineAnimalsReceptor Serotonin 5-HT2AATP Binding Cassette Transporter Subfamily B Member 1ReceptorBiological PsychiatryP-glycoproteinMice KnockoutBrain uptakeBiological TransportLigand (biochemistry)Frontal LobeFluorobenzenesPsychiatry and Mental healthNeuropsychology and Physiological Psychologymedicine.anatomical_structureBlood-Brain BarrierPositron-Emission Tomographybiology.proteinNeuroscienceNeuropsychobiology
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