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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
Machine learning has recently become a promising technique in fluid mechanics, especially for active flow control (AFC) applications. A recent work [Rabault et al., J. Fluid Mech. 865, 281–302 (2019)] has demonstrated the ...
(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2021)
With the introduction of the exchange-traded German wind power futures, opportunities for German wind power producers to hedge their volumetric risk are present. We propose two continuous-time multivariate models for wind ...
(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2021)
Recently, Brannan and Vergnioux showed that the orthogonal free quantum group factors [Formula: see text] have Jung’s strong [Formula: see text]-boundedness property, and hence are not isomorphic to free group factors. We ...
(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2021)
This paper considers data-based real-time adaptive Fault Detection (FD) in Grid-connected PV (GPV) systems under Power Point Tracking (PPT) modes during large variations. Faults under PPT modes remain undetected for longer ...
(Doctoral thesis / Doktoravhandling, 2021)
Submarine mass movements are important sources for tsunamis with potential destructive consequences at coastlines. A famous example from historical records is, for instance, the 1929 Grand Banks tsunami in Canada. This ...
(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2021)
We introduce a mean counting function for Dirichlet series, which plays the same role in the function theory of Hardy spaces of Dirichlet series as the Nevanlinna counting function does in the classical theory. The existence ...
(Doctoral thesis / Doktoravhandling, 2021)
The polar oceans consist of open water, continuous ice covers and zones of broken ice floes of various sizes in the transition between water and ice. As the waves from the open ocean travel into the zone of ice floes, the ...
(Doctoral thesis / Doktoravhandling, 2021)
Landslides can generate large tsunamis when falling into lakes and the sea. In order to protect coastal areas and communities we need to predict these events. Mathematical models have become a popular method for this task. ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
Cardiac muscle cells can exhibit complex patterns including irregular behaviour such as chaos or (chaotic) early afterdepolarisations (EADs), which can lead to sudden cardiac death. Suitable mathematical models and their ...
(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2021)
The steric repulsion between proteins on biological membranes is one of the most generic mechanisms that cause membrane shape changes. We present a minimal model in which a spontaneous curvature is induced by asymmetric ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
Background
Gestational age is a useful proxy for assessing developmental maturity, but correct estimation of gestational age is difficult using clinical measures. DNA methylation at birth has proven to be ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
This study presents wave measurements in the Marginal Ice Zone (MIZ) obtained from ship mounted sensors. The system combines altimeter readings from the ship bow with ship motion correction data to provide estimated single ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
Many of the widely used models for description of nonlinear surface gravity waves, in deep or shallow water, such as High Order Spectral Method (HOSM) and Boussinesq-type equations, rely on the elimination of the vertical ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
108844
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
Background
Studies of mammalian CSF dynamics have been focused on three things: paravascular flow, pressure and pulsatility, and “bulk” flow; and three (respective) potential motive forces have been ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
A sharp version of a recent inequality of Kovalev and Yang on the ratio of the (H1)∗ and H4 norms for certain polynomials is obtained. The inequality is applied to establish a sharp and tractable sufficient condition for ...
(Doctoral thesis / Doktoravhandling, 2021)
Both in science and industry, the sizes of data sets are growing. It is not uncommon to encounter sets containing millions or even billions of measurements. Without appropriate tools for turning such enormous amounts of ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
System logs or log files containing textual messages with associated time stamps are generated by many technologies and systems. The clustering technique proposed in this paper provides a tool to discover and identify ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
We investigate the probabilistic and analytic properties of Volterra processes constructed as pathwise integrals of deterministic kernels with respect to the Hölder continuous trajectories of Hilbert-valued Gaussian ...
(Doctoral thesis / Doktoravhandling, 2021)
In our modern society, with the bourgeoning of e-commerce and online streaming platforms, customers are overwhelmed by the choices. One important approach to solve this problem is recommender systems. Recommender systems ...
(Doctoral thesis / Doktoravhandling, 2021)
The development of research and exploration in Arctic waters is very common nowadays. One of the environmental difficulties to carry out research in these regions is the icing of surfaces. After short periods of time, ice ...
(Master thesis / Masteroppgave, 2021)
Fraud data often includes a dichotomous response variable with class imbalance, covariates with various marginal distributions and complex dependencies. Our goal is to predict the probability of fraud given the covariates. ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
We study the dynamic wetting of a self-propelled viscous droplet using the time-dependent lubrication equation on a conical-shaped substrate for different cone radii, cone angles and slip lengths. The droplet velocity is ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
We study the stability of a unique weak solution to certain parabolic systems with nonstandard growth condition, which are additionally dependent on a cross-diffusion term. More precisely, we show that two unique weak ...
(Master thesis / Masteroppgave, 2021)
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
Two-phase oil and gas flow were simulated in an entirely eccentric annulus and compared with experimental data at horizontal, 4, 10, and 90° inclination. The gas-phase was sulphur hexafluoride and the liquid phase a mixture ...
(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2021)
The present study was originally motivated by some intriguing exact solutions for waves propagating in nonuniform media. In particular, for special depth profiles reflected waves did not appear and ray theory became exact. ...
(Doctoral thesis / Doktoravhandling, 2021)
Rogue waves are unexpected and unusually larger waves than their surrounding and can be dangerous to ship and offshore structures. In normally distributed wave fields also known as Gaussian sea, rogue waves actually exist, ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
Graph products of groups were introduced by Green in her thesis [32]. They have an operator algebraic counterpart introduced and explored in [14]. In this paper we prove Khintchine type inequalities for general C⁎-algebraic ...
(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2021)
Experimental and numerical evidence have shown that nonuniform bathymetry may alter significantly the statistical properties of surface elevation in irregular wave fields. The probability of “rogue” waves is increased near ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
Publication bias and p-hacking are two well-known phenomena that strongly affect the scientific literature and cause severe problems in meta-analyses. Due to these phenomena, the assumptions of meta-analyses are seriously ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
Operating in energy and commodity markets require a management of risk using derivative products such as forward and futures, as well as options on these. Many of the popular stochastic models for spot dynamics and weather ...
(Doctoral thesis / Doktoravhandling, 2021)
Many important results in mathematics deal with the question of figuring out what objects are ‘the same’. One way of rigorously dealing with this is through the notion of isomorphic objects. However, it is sometimes better ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
Plants and insects use slender conical structures to transport and collect small droplets, which are propelled along the conical structures due to capillary action. These droplets can deposit a fluid film during their ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
This work introduces the deconvolution as a technique to reconstruct missing information in data. While the method was originally developed for ocean waves, it will be useful in a wider range of applications where gaps in ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
Previous-30 treatments of multivariate non-causal time series have assumed stationarity. In this article, we consider integrated processes in a non-causal setting. We generalize the Johansen–Granger representation for ...
(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2021)
We propose a new class of rough stochastic volatility models obtained by modulating the power-law kernel defining the fractional Brownian motion (fBm) by a logarithmic term, such that the kernel retains square integrability ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
Across the field of education research there has been an increased focus on the development, critique, and evaluation of statistical methods and data usage due to recently created, very large datasets and machine learning ...
(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2021)
We relate the problem of best low-rank approximation in the spectral norm for a matrix $A$ to Kolmogorov $n$-widths and corresponding optimal spaces. We characterize all the optimal spaces for the image of the Euclidean ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
Battery systems are becoming an increasingly attractive alternative for powering ocean going ships, and the number of fully electric or hybrid ships relying on battery power for propulsion and manoeuvring is growing. In ...
(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2021)
Given an ample groupoid, we construct a spectral sequence with groupoid homology with integer coefficients on the second sheet, converging to the K-groups of the (reduced) groupoid C∗-algebra, provided the groupoid has ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
Our society generates extensive amounts of municipal solid waste (MSW), which are mainly incinerated for volume reduction and energy recovery. Though, MSW incineration generates hazardous air pollution control (APC) residues ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
Recent works have presented promising results from the application of machine learning (ML) to the modeling of flow rates in oil and gas wells. Encouraging results and advantageous properties of ML models, such as ...
(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2021)
In this paper we provide explicit upper and lower bounds on certain L2n-widths, i.e., best constants in L2 approximation. We further describe a numerical method to compute these n-widths approximately and prove that this ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
We introduce and develop a general paradigm for combining information across diverse data sources. In broad terms, suppose 𝜑 is a parameter of interest, built up via components 𝜓1,…,𝜓𝑘 from data sources 1, … , k. The ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
Abstract Experimental results from a combined wind–wave tank are presented. Wind profiles and resulting wind–wave spectra are described, and an investigation of the airflow above breaking waves is presented. Monochromatic ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
Economic and technological development has increased the amount, density and complexity of maritime traffic, which has resulted in new challenges. One challenge is conforming to the distinct evasion manoeuvres required by ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
Abstract Due to rapid developments in machine learning, and in particular neural networks, a number of new methods for time-to-event predictions have been developed in the last few years. As neural networks are parametric ...
(Chapter / Bokkapittel / PublishedVersion; Peer reviewed, 2021)
Battery systems are becoming an increasingly attractive alternative for powering ocean going ships, and the number of fully electric or hybrid ships relying on battery power for propulsion and maneuvering is growing. In ...
(Master thesis / Masteroppgave, 2021)
Compressed sensing has roused great interest in research and many industries over the last few decades. This is because we can recover signals from vastly undersampled measurements, under certain assumptions: sparsity, ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
In recent years, Bayesianmeta-analysis expressed by a normal–normal hierarchical model (NNHM) has been widely used for combining evidence from multiple studies. Data provided for the NNHM are frequently based on a small ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
Abstract We establish a local theory, i.e., existence, uniqueness and blow-up criterion, for a general family of singular SDEs in Hilbert spaces. The key requirement relies on an approximation property that allows us to ...
(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2021)
This paper proposes a novel Improved Maximum Power Point Tracking (IMPPT) algorithm to extract the maximum available power from a direct-drive Permanent-Magnet Synchronous Generator (PMSG) based standalone Small-scale ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
This article is devoted to the extension of the theory of rough paths in the context of Volterra equations with possibly singular kernels. We begin to describe a class of two parameter functions defined on the simplex ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
Environmental contours are used to simplify the process of design response analysis. A wide variety of contour methods exist; however, there have been a very limited number of comparisons of these methods to date. This ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
Non-stationary Extreme Value Analysis (NEVA) allows to determine the probability of exceedance of extreme sea states taking into account trends in the time series of data at hand. In this work, we analyse the reliability ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
Environmental contours are widely used as a basis for e.g., ship design, especially in early design phases. The traditional approach to such contours is based on the well-known Rosenblatt transformation. Here we focus on ...
(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2021)
We study ordinary differential equations (ODEs) with vector fields given by general Schwartz distributions, and we show that if we perturb such an equation by adding an “infinitely regularizing” path, then it has a unique ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
In this work we investigate the long-time behavior for Markov processes obtained as the unique mild solution to stochastic partial differential equations in a Hilbert space. We analyze the existence and characterization ...
(Master thesis / Masteroppgave, 2021)
While neural networks have been demonstrated to be highly successful in mathematical and statistical modelling of a comprehensive selection of problems, their application to inverse problems is not without complications. ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
The incompressible μ(I)-rheology has been used to study subaerial granular flows with remarkable success. For subaquatic granular flows, drag between grains and the pore fluid is substantially higher and the physical ...
(Master thesis / Masteroppgave, 2021)
Hovedmålet for denne oppgaven er å undersøke og sammenlikne to symmetriske krypteringsalgoritmer, AES og Kalyna. I oppgaven presenteres AES og Kalynas funksjoner og sammenlikner AES og Kalynas forskjellige funksjoner i ...
(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2021)
Fault detection, diagnosis, identification and location are crucial to improve the sensitivity and reliability of system protection. This maintains power systems continuous proper operation; however, it is challenging in ...
(Master thesis / Masteroppgave, 2021)
Building upon recent work by Binda, Park, and Østvær we construct a theory of motives with compact support in the setting of logarithmic algebraic geometry. Starting from the notion of finite logarithmic correspondences ...
(Master thesis / Masteroppgave, 2021)
In this master's thesis we derive a connection between filtration shifts and differentials in a spectral sequence. We assume that the spectral sequence comes from a Cartan-Eilenberg system, and we develop a framework to ...
(Master thesis / Masteroppgave, 2021)
Deep Learning (DL) has already begun to find its way into the computational scientist's toolkit, yet the amount of material on numerical analysis of these techniques is somewhat lacking. In recent years, an instability ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
The process of recombination between variable (V), diversity (D), and joining (J) immunoglobulin (Ig) gene segments determines an individual's naive Ig repertoire and, consequently, (auto)antigen recognition. VDJ recombination ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
Abstract We show that the pseudoeffective cone of k -cycles on a complete complexity-one T -variety is rational polyhedral for any k , generated by classes of T -invariant subvarieties. When X is also rational, we give a ...
(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2021)
A novel Dynamic Kernel PCA (DKPCA) method is developed for process monitoring in nonlinear dynamical systems. Classical DKPCA approaches still exhibit vague linearity assumptions to determine the number of principal ...
(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2021)
We derive a series expansion by Hermite polynomials for the price of an arithmetic Asian option. This requires the computation of moments and correlators of the underlying asset price which for a polynomial jump–diffusion ...
(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2021)
Detailed water kinematics are important for understanding atmosphere–ice–ocean energy transfer processes in the Arctic. There are few in situ observations of 2D velocity fields in the marginal ice zone. Particle tracking ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
An experimental investigation of flexural-gravity waves was performed in the Hamburg Ship Model Basin HSVA ice tank. Physical characteristics of the water-ice system were measured in several locations of the tank with a ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
Abstract We revisit the construction of wavelets on the interval with various degrees of polynomial exactness, and explain how existing schemes for orthogonal- and Spline wavelets can be extended to compactly supported ...
(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2021)
We introduce the notion of one-sided mapping cones of positive linear maps between matrix algebras. These are convex cones of maps that are invariant under compositions by completely positive maps from either the left or ...
(Chapter / Bokkapittel / PublishedVersion; Peer reviewed, 2021)
Several different approaches to modelling stochastic deterioration for optimising maintenance have been suggested in the reliability literature. These include component lifetime distributions, which have the disadvantage ...
(Master thesis / Masteroppgave, 2021)
In this master, we are going to generate period internal waves with two immiscible fluids and investigate the drift using PTV. The motivation is to compare to Weber and Christensen's theory on how spatial damping transfers ...
(Master thesis / Masteroppgave, 2021)
(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2021)
Turing’s famous ‘machine’ model constitutes the first intuitively convincing framework for computing with real numbers. Kleene’s computation schemes S1–S9 extend Turing’s approach and provide a framework for computing with ...
(Master thesis / Masteroppgave, 2021)
Forsikringsselskaper rundt om i verden tilbyr mange ulike typer forsikringskontrakter. Disse skal gi erstatning dersom spesifikke hendelser som er spesifisert i kontraktene inntreffer. En type forsikring som er lite utbredt ...
(Master thesis / Masteroppgave, 2021)
This master thesis reviews and discusses the literature on discrete choice methods. Discrete choice modelling is an effective tool for predicting choice behavior, analyzing consumer preferences, and determining consumption ...
(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2021)
Deep reinforcement learning (DRL) has recently been adopted in a wide range of physics and engineering domains for its ability to solve decision-making problems that were previously out of reach due to a combination of ...
(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2021)
This paper presents an effective strategy for controlling an Interleaved DC/DC Boost Converter (IBC) that is employed for reducing the current fluctuations in a 6 kW Proton Exchange Membrane Fuel Cell (PEMFC). The proposed ...
(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2021)
Deep Reinforcement Learning (DRL) has recently spread into a range of domains within physics and engineering, with multiple remarkable achievements. Still, much remains to be explored before the capabilities of these methods ...
(Journal article / Tidsskriftartikkel / SubmittedVersion, 2021)
(Master thesis / Masteroppgave, 2021)
Modeling time series and systems that exhibit an evolution in time is of interest in several fields, and one class of models that can be used for modeling such systems is state space models. One of the most common tools ...
(Journal article / Tidsskriftartikkel / PublishedVersion, 2021)
We investigate the space-time regularity of the local time associated with Volterra–Lévy processes, including Volterra processes driven by α-stable processes for α∈(0,2]. We show that the spatial regularity of the local ...
(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2021)
A cohomology class of a smooth complex variety of dimension n has coniveau at least c if it vanishes in the complement of a closed subvariety of codimension at least c, and it has strong coniveau at least c if it comes by ...
Merton’s portfolio problem: A Monte Carlo study Restricted Access
(Master thesis / Masteroppgave, 2021)
A classical problem in continuous time finance is Merton’s portfolio problem. The problem was formulated and solved in 1969 by economist and Nobel prize winner Robert C. Merton. At each instant of time, a risk averse ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
We introduce a rough perturbation of the Navier–Stokes system and justify its physical relevance from balance of momentum and conservation of circulation in the inviscid limit. We present a framework for a well-posedness ...
(Journal article / Tidsskriftartikkel / SubmittedVersion, 2021)
We analyse forward prices observed at the Fishpool market, and propose a two-factor continuous-time stochastic process for modelling the time dynamics. The data analysis reveals that the two factors can be assumed to be a ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
Background
Several central nervous system diseases are associated with disturbed cerebrospinal fluid (CSF) flow patterns and have typically been characterized in vivo by phase-contrast magnetic resonance ...
(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2021)
Rational quartic spectrahedra in 3-space are semialgebraic convex subsets in R3 of semidefinite, real symmetric (4×4)-matrices, whose boundary admits a rational parameterization. The Zariski closure in CP3 of the boundary ...
(Doctoral thesis / Doktoravhandling, 2021)
In this thesis, two-phase flow in an annular pipe geometry is studied using an open-source software known as OpenFOAM. The data collected through the simulations in this thesis are compared to experimental data collected ...
(Journal article / Tidsskriftartikkel / SubmittedVersion, 2021)
We propose a refined version of the stochastic SEIR model for epidemic of the new corona virus SARS-Cov-2, causing the COVID-19 disease, taking into account the spread of the virus due to the regular infected individuals ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
Abstract We study C*-algebras generated by left regular representations of right LCM one-relator monoids and Artin–Tits monoids of finite type. We obtain structural results concerning nuclearity, ideal structure and pure ...
(Master thesis / Masteroppgave, 2021)
With the advent of Industry 4.0, Predictive Maintenance (PdM) has garnered a lot of interest, both academically and in the industry. This thesis will be developing and using machine learning methods for PdM, using real ...
(Master thesis / Masteroppgave, 2021)
In regression problems, it is often of interest to assume that the relationship between a predictor variable and a response variable is monotone. In this thesis, we focus on general additive regression, in which each ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
Background
The overall aim of this study is to examine the effect of prenatal maternal anxiety on birthweight and gestational age, controlling for shared family confounding using a sibling comparison design.
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