Search results for "likelihood"

showing 10 items of 264 documents

Multiple overseas dispersal in amphibians

2003

Amphibians are thought to be unable to disperse over ocean barriers because they do not tolerate the osmotic stress of salt water. Their distribution patterns have therefore generally been explained by vicariance biogeography. Here, we present compelling evidence for overseas dispersal of frogs in the Indian Ocean region based on the discovery of two endemic species on Mayotte. This island belongs to the Comoro archipelago, which is entirely volcanic and surrounded by sea depths of more than 3500 m. This constitutes the first observation of endemic amphibians on oceanic islands that did not have any past physical contact to other land masses. The two species of frogs had previously been tho…

MovementBiogeographyMolecular Sequence DataMantellidaeBiologyphylogenyDNA MitochondrialComorosGeneral Biochemistry Genetics and Molecular BiologyEvolution MolecularAmphibiaddc:570MadagascarVicarianceAnimalsIndian OceanPhylogenybiogeographyDNA PrimersGeneral Environmental ScienceLikelihood FunctionsBase SequenceGeographyModels GeneticGeneral Immunology and MicrobiologyEcologySequence Analysis DNAGeneral MedicineSalt waterBiological dispersalAnuraGeneral Agricultural and Biological SciencesResearch Article
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Penalized inference in multivariate ordered logistic models: theory and applications

2011

Multivariate Logistic Model Penalized LikelihoodSettore SECS-S/01 - Statistica
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Association between climate and new daily diagnoses of COVID-19

2020

AbstractBackgroundAlthough evidence is accumulating that climate conditions may positively or negatively influence the scale of coronavirus disease 2019 (COVID-19) outbreaks, uncertainty remains concerning the real impact of climate factors on viral transmission. Methods. The number of new daily cases of COVID-19 diagnosed in Verona (Italy) was retrieved from the official website of Veneto Region, while information on daily weather parameters in the same area was downloaded from IlMeteo website, a renowned Italian technological company specialized in weather forecasts. The search period ranged between March 1 to November 11, 2020. The number of new daily COVID-19 cases and meteorological da…

Multivariate analysisCoronavirus disease 2019 (COVID-19)Leadership and ManagementStrategy and Management2020. The number of new daily COVID-19 cases and meteorological data in Verona were correlated using both univariate and multivariate analysis. Results: The number of daily COVID-19 diagnoses in Verona was positively associated with the number of days in lockdown and humidity1% decrease in humidityWind speedmin and max temperatureand influence the likelihood or course of local COVID-19 outbreaks. Preventive measuresHealth Information Managementa renowned Italian technological company specialized in weather forecasts. The search period ranged between March 1 and November 11mean air temperature1.2% and 5.4% reduction in new COVID-19 daily diagnoses. A significant difference was observed in values of all-weather parameters recorded in Verona between days with &ltHealth Policy1 km/h increase in wind speed and day with rainfall were independently associated with 1.0%Significant differencehumidityUnivariateOutbreakHumidityand inversely correlated with meanmean wind speed and number of days with rainfall. Days of lockdownwhile information on daily weather parameters in the same area was downloaded from IlMeteo websitetesting policies and hospital preparedness should be reinforced during periods of higher meteorological risk and in local environments with adverse climate conditions.Background: Although evidence is accumulating that climate conditions may positively or negatively influence the scale of coronavirus disease 2019 (COVID-19) outbreaks0.3%uncertainty remains concerning the real impact of climate factors on viral transmission. Methods: The number of new daily cases of COVID-19 diagnosed in Verona (Italy) was retrieved from the official website of Veneto RegionGeography100 or ≥100 new daily COVID-19 diagnoses. Conclusions: Climate conditions may play an essential role in conditions of viral transmissionAir temperaturemean wind speed and number of days with rainfall remained significantly associated in multivariate analysis. The four weather parameters contributed to explaining 61% of variance in new daily COVID-19 diagnoses. Each 1% increase in air temperatureBackground: Although evidence is accumulating that climate conditions may positively or negatively influence the scale of coronavirus disease 2019 (COVID-19) outbreaks uncertainty remains concerning the real impact of climate factors on viral transmission. Methods: The number of new daily cases of COVID-19 diagnosed in Verona (Italy) was retrieved from the official website of Veneto Region while information on daily weather parameters in the same area was downloaded from IlMeteo website a renowned Italian technological company specialized in weather forecasts. The search period ranged between March 1 and November 11 2020. The number of new daily COVID-19 cases and meteorological data in Verona were correlated using both univariate and multivariate analysis. Results: The number of daily COVID-19 diagnoses in Verona was positively associated with the number of days in lockdown and humidity and inversely correlated with mean min and max temperature mean wind speed and number of days with rainfall. Days of lockdown mean air temperature humidity mean wind speed and number of days with rainfall remained significantly associated in multivariate analysis. The four weather parameters contributed to explaining 61% of variance in new daily COVID-19 diagnoses. Each 1% increase in air temperature 1% decrease in humidity 1 km/h increase in wind speed and day with rainfall were independently associated with 1.0% 0.3% 1.2% and 5.4% reduction in new COVID-19 daily diagnoses. A significant difference was observed in values of all-weather parameters recorded in Verona between days with <100 or ≥100 new daily COVID-19 diagnoses. Conclusions: Climate conditions may play an essential role in conditions of viral transmission and influence the likelihood or course of local COVID-19 outbreaks. Preventive measures testing policies and hospital preparedness should be reinforced during periods of higher meteorological risk and in local environments with adverse climate conditions.DemographyJournal of Hospital Management and Health Policy
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Testing Equality of Multiple Power Spectral Density Matrices

2018

This paper studies the existence of optimal invariant detectors for determining whether P multivariate processes have the same power spectral density. This problem finds application in multiple fields, including physical layer security and cognitive radio. For Gaussian observations, we prove that the optimal invariant detector, i.e., the uniformly most powerful invariant test, does not exist. Additionally, we consider the challenging case of close hypotheses, where we study the existence of the locally most powerful invariant test (LMPIT). The LMPIT is obtained in the closed form only for univariate signals. In the multivariate case, it is shown that the LMPIT does not exist. However, the c…

Multivariate statisticsGaussian02 engineering and technologyGeneralized likelihood tatio test (GLRT)Toeplitz matrixUniformly most powerful invariant test (UMPIT)01 natural sciencesElectronic mail010104 statistics & probabilitysymbols.namesakePower spectral density (PSD)0202 electrical engineering electronic engineering information engineeringApplied mathematics0101 mathematicsElectrical and Electronic EngineeringGeneralized likelihood ratio test (GLRT)MathematicsTelecomunicaciones1299 Otras Especialidades MatemáticasDetectorUnivariateSpectral density020206 networking & telecommunicationsInvariant (physics)Toeplitz matrixSignal ProcessingsymbolsTime-SeriesLocally most powerful invariant test (LMPIT)
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Locally optimal invariant detector for testing equality of two power spectral densities

2018

This work addresses the problem of determining whether two multivariate random time series have the same power spectral density (PSD), which has applications, for instance, in physical-layer security and cognitive radio. Remarkably, existing detectors for this problem do not usually provide any kind of optimality. Thus, we study here the existence under the Gaussian assumption of optimal invariant detectors for this problem, proving that the uniformly most powerful invariant test (UMPIT) does not exist. Thus, focusing on close hypotheses, we show that the locally most powerful invariant test (LMPIT) only exists for univariate time series. In the multivariate case, we prove that the LMPIT do…

Multivariate statisticsSeries (mathematics)Computer scienceGaussianDetectorUnivariateSpectral density020206 networking & telecommunications02 engineering and technologyUniformly most powerful invariant test (UMPIT)01 natural sciencesMatrix decomposition010104 statistics & probabilitysymbols.namesakePower spectral density (PSD)0202 electrical engineering electronic engineering information engineeringsymbols0101 mathematicsInvariant (mathematics)Time seriesHypothesis testGeneralized likelihood ratio test (GLRT)AlgorithmLocally most powerful invariant test (LMPIT)Statistical hypothesis testing
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Adaptive independent vector analysis for multi-subject complex-valued fMRI data.

2017

Abstract Background Complex-valued fMRI data can provide additional insights beyond magnitude-only data. However, independent vector analysis (IVA), which has exhibited great potential for group analysis of magnitude-only fMRI data, has rarely been applied to complex-valued fMRI data. The main challenges in this application include the extremely noisy nature and large variability of the source component vector (SCV) distribution. New method To address these challenges, we propose an adaptive fixed-point IVA algorithm for analyzing multiple-subject complex-valued fMRI data. We exploited a multivariate generalized Gaussian distribution (MGGD)- based nonlinear function to match varying SCV dis…

Multivariate statisticscomplex-valued fMRI dataComputer scienceSpeech recognitionRestModels Neurological02 engineering and technologyMotor Activityta3112Shape parameterFingers03 medical and health sciencesMatrix (mathematics)0302 clinical medicine0202 electrical engineering electronic engineering information engineeringHumansComputer SimulationGeneralized normal distributionDefault mode networkta217ta113shape parametersubspace de-noisingBrain MappingLikelihood Functionsbusiness.industryGeneral NeuroscienceBrain020206 networking & telecommunicationsPattern recognitionMagnetic Resonance ImagingNonlinear systemNonlinear Dynamicsindependent vector analysis (IVA)MGGDMultivariate AnalysisAuditory PerceptionnoncircularityArtificial intelligenceNoise (video)businessArtifactspost-IVA phase de-noising030217 neurology & neurosurgerySubspace topologyAlgorithmsJournal of neuroscience methods
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Respiratory proteins in Sipunculus nudus--implications for phylogeny and evolution of the hemerythrin family.

2009

Three major classes of respiratory proteins are known, hemoglobin, molluscan and arthropod hemocyanin, and hemerythrin (Hr). Similar to hemoglobin, respiratory Hr is packed into erythrocytes floating in the coelomic fluid and is only known from sipunculids, brachiopods, and priapulids. Owing to this scattered distribution, the presence of Hr is generally assumed to be the plesiomorphic condition without phylogenetic importance. By sequencing 2000 Expressed Sequence Tags (ESTs) from Sipunculus nudus, we found 75 Hr-coding ESTs assembled to 20 cDNA contigs classified as four distinct Hr isoforms: three polymeric Hrs (subunit A, A', and B) and the monomeric myo-hemerythrin (myoHr). Phylogeneti…

NematodaPhysiologymedicine.medical_treatmentBiochemistryHemerythrinEvolution MolecularPhylogeneticsSipunculus nudusmedicineAnimalsProtein IsoformsMolecular BiologyPhylogenySipunculaExpressed Sequence TagsExpressed sequence tagLikelihood FunctionsAnnelidPhylogenetic treebiologyRespirationHemocyaninBayes TheoremAnatomybiology.organism_classificationHemerythrinBiochemistryGene Expression RegulationMultigene FamilyComparative biochemistry and physiology. Part B, Biochemistrymolecular biology
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Emergence and Phylodynamics of Citrus tristeza virus in Sicily, Italy

2013

Citrus tristeza virus (CTV) outbreaks were detected in Sicily island, Italy for the first time in 2002. To gain insight into the evolutionary forces driving the emergence and phylogeography of these CTV populations, we determined and analyzed the nucleotide sequences of the p20 gene from 108 CTV isolates collected from 2002 to 2009. Bayesian phylogenetic analysis revealed that mild and severe CTV isolates belonging to five different clades (lineages) were introduced in Sicily in 2002. Phylogeographic analysis showed that four lineages co-circulated in the main citrus growing area located in Eastern Sicily. However, only one lineage (composed of mild isolates) spread to distant areas of Sici…

Nonsynonymous substitutionCitrusGenetic-variationLineage (evolution)Population Dynamicslcsh:MedicinePopulation geneticsPlant Sciencelcsh:SciencePhylogenetic analysesPhylogenyGeneticsMultidisciplinarybiologyPhylogenetic treeGeographyCitrus tristeza virusAgriculturePhylogeneticsItalyRNA ViralEvolutionary dynamicsCross-protectionSequence AnalysisResearch ArticleClosterovirusDNA ComplementaryMolecular Sequence DataPlant PathogensCropsMicrobiologyViral EvolutionFruitsGenetic driftSpecies SpecificityVirologyMosaic-virusGenetic variationCTV Phylodynamics SicilyEvolutionary SystematicsPopulation-structureHost passageBiologyPlant DiseasesEvolutionary BiologyMaximum-likelihoodlcsh:RSettore AGR/12 - Patologia VegetaleComputational BiologyGenetic VariationBayes TheoremSequence Analysis DNAPlant Pathologybiology.organism_classificationAgronomyViral phylodynamicsDNA polymorphismEvolutionary biologyMolecular evolutionlcsh:Q
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NATURAL SELECTION AND THE ORGAN-SPECIFIC DIFFERENTIATION OF HIV-1 V3 HYPERVARIABLE REGION

2004

The existence of organ-specific HIV-1 populations within infected hosts has been studied for many years; nonetheless results reported by different authors are somewhat discrepant. To tackle this problem, we used a population genetics approach to analyze previously published data from the V3 hypervariable region of the envelope env gene. Our results are compatible with a population subdivision by organs in 95% of individuals analyzed at autopsy. In addition, populations infecting the nervous system and testicles clearly appear as differentiated subsets of the so-called macrophage-tropic variants. Liver and kidney may harbor differentiated populations as well. Although it is widely accepted t…

Nonsynonymous substitutionPopulationPopulation geneticsHIV Envelope Protein gp120BiologyEvolution MolecularGeneticsCluster AnalysisHumansSelection GeneticeducationEcology Evolution Behavior and SystematicsGeneticsAnalysis of VarianceLikelihood Functionseducation.field_of_studyNatural selectionBase SequenceModels GeneticMechanism (biology)HIVPeptide FragmentsHypervariable regionGenetics PopulationOrgan SpecificityViral evolutionAdaptationDatabases Nucleic AcidGeneral Agricultural and Biological SciencesSequence AlignmentEvolution
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Comparative Sequence Analysis ofMycobacterium lepraeand the New Leprosy-CausingMycobacterium lepromatosis

2009

ABSTRACTMycobacterium lepromatosisis a newly discovered leprosy-causing organism. Preliminary phylogenetic analysis of its 16S rRNA gene and a few other gene segments revealed significant divergence fromMycobacterium leprae, a well-known cause of leprosy, that justifies the status ofM. lepromatosisas a new species. In this study we analyzed the sequences of 20 genes and pseudogenes (22,814 nucleotides). Overall, the level of matching of these sequences withM. lepraesequences was 90.9%, which substantiated the species-level difference; the levels of matching for the 16S rRNA genes and 14 protein-encoding genes were 98.0% and 93.1%, respectively, but the level of matching for five pseudogenes…

Nonsynonymous substitutionSequence analysisPseudogeneMolecular Sequence Datamedicine.disease_causePolymerase Chain ReactionMicrobiologyMycobacteriumBacterial ProteinsPhylogeneticsLeprosyRNA Ribosomal 16SmedicineMolecular BiologyMycobacterium lepraePhylogenyGeneticsMycobacterium lepromatosisBase CompositionLikelihood FunctionsbiologyPhylogenetic treeComputational BiologySequence Analysis DNAbiology.organism_classificationMycobacterium lepraePseudogenesMycobacteriumJournal of Bacteriology
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