Sökning: "covariance function"

Visar resultat 6 - 10 av 76 avhandlingar innehållade orden covariance function.

  1. 6. Aging Along the Hippocampal Axis : Structure, Function and Whole-brain Connections in Association with Memory

    Författare :Kristin Nordin; Hedvig Söderlund; Agneta Herlitz; Jessica Damoiseaux; Uppsala universitet; []
    Nyckelord :SAMHÄLLSVETENSKAP; SOCIAL SCIENCES; hippocampus; aging; longitudinal-axis; episodic memory; spatial memory; connectivity; fMRI; Psychology; Psykologi;

    Sammanfattning : Hippocampus-dependent functions display marked reductions in older age, an observation that has led to the extensive study of age effects on hippocampal properties. Even though research indicates that the hippocampus is structurally and functionally heterogeneous along its longitudinal axis, its anterior and posterior regions differentially supporting episodic and spatial memory representations, few studies explicitly consider age effects in relation to axis. LÄS MER

  2. 7. Carbon stocks and fluxes in a young Siberian larch (Larix sibirica) plantation in Iceland

    Författare :Brynhildur Bjarnadottir; Institutionen för naturgeografi och ekosystemvetenskap; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; interannual variability; carbon balance; Larix sibirica; afforestation; stock-change method; carbon sequestration; eddy covariance; biomass functions;

    Sammanfattning : The understanding of how forests function with respect to carbon (C) balance and its interaction with the climate system is a fundamental question in climate change research. Another important question is how large the sink for CO2 is in northern forests and how it varies with forest type, management, stand age and with external factors, such as climate variability. LÄS MER

  3. 8. On Estimation and Prediction in Linear Mixed Models : A new approach to studying equal BLUEs and BLUPs

    Författare :Azadeh Chizarifard; Tatjana von Rosen; Katarzyna Filipiak; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Best linear unbiased estimator; Best linear unbiased predictor; Linear zero function; Matrix equations; statistik; Statistics;

    Sammanfattning : Linear mixed models (LMMs) are widely used to analyze repeated, longitudinal, or clustered data in many disciplines, such as biology, medicine, psychology, sociology, economics, etc. One of the essential components of a linear mixed model is its covariance structure, i.e. LÄS MER

  4. 9. Local Polynomial Regression with Application on Lidar Measurements

    Författare :Torgny Lindström; Matematisk statistik; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Mathematics; Matematik; differential equations; Funktioner; differentialekvationer; variance-function estimation.; spatial dependence; nonparametric; local polynomial regression; local bandwidth selection; lidar; heteroscedasticity; Bivariate estimation; differential absorption; Functions;

    Sammanfattning : This thesis deals with the problem of estimating a function or one of its derivatives from a set of measurements, mainly of a bivariate or spatial nature which is so common in environmental applications. In this work particular attention has been on the lidar (light detection and ranging) application which is a versatile technique for measurement of among other things atmospheric trace gases. LÄS MER

  5. 10. Effect of Uncertainty of Rock Properties on Radionuclide Transport by Groundwater : Implications for Performance Assessments of the Repository of Spent Nuclear Fuel in Heterogeneous Bedrock

    Författare :Shulan Xu; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Earth sciences; Radionuclide migration; heterogeneous rock property; stochastic process spectral analysis; temporal moments; auto-covariance functions; sorption kinetics; performance assessment; Geovetenskap; Earth sciences; Geovetenskap; Sedimentology; sedimentologi;

    Sammanfattning : The overall objective of the current study is to develop a quantitative understanding of the effects of spatial variability in physical and geochemical properties of crystalline rock on the migration of radionuclides along a single fracture in bedrock. A stochastic model was developed to describe the transport of solutes in fractured rock. LÄS MER