| 1. |
- Baresel, Christian, et al.
(författare)
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Uncertainty-Accounting Environmental Policy and Management of Water Systems
- 2007
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Ingår i: Environmental Science & Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 41:10, s. 3653–3659-
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Tidskriftsartikel (refereegranskat)abstract
- Environmental policies for water quality and ecosystemmanagement do not commonly require explicit stochasticaccounts of uncertainty and risk associated with thequantification and prediction of waterborne pollutant loadsand abatement effects. In this study, we formulate andinvestigate a possible environmental policy that does requirean explicit stochastic uncertainty account. We compareboth the environmental and economic resource allocationperformance of such an uncertainty-accounting environmentalpolicy with that of deterministic, risk-prone and riskaverseenvironmental policies under a range of differenthypothetical, yet still possible, scenarios. The comparisonindicates that a stochastic uncertainty-accountingpolicy may perform better than deterministic policies overa range of different scenarios. Even in the absence ofreliable site-specific data, reported literature values appearto be useful for such a stochastic account of uncertainty.
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| 2. |
- Pavlenko, Tatjana
(författare)
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Feature Informativeness, Curse-of-Dimensionality and Error Probability in Discriminant Analysis
- 2001
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis is based on four papers on high-dimensional discriminant analysis. Throughout, the curse-of-dimensionality effect on the precision of the discrimination performance is emphasized. A growing dimension asymptotic approach is used for assessing this effect and the limiting error probability are taken as the performance criteria. A combined effect of a high dimensionality and feature informativeness on the discrimination performance is evaluated.
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| 3. |
- Pihlsgård, Mats
(författare)
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Two-Barrier Problems in Applied Probability: Algorithms and Analysis
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis consists of five papers (A-E). In Paper A, we study transient properties of the queue length process in various queueing settings. We focus on computing the mean and the Laplace transform of the time required for the queue length starting at $x0. We define the loss rate due to the reflection. The main result is sharp asymptotics for the loss rate as $K$ tends to infinity. As a major example, we consider the case where the increments of the random walk may be written as the difference between two phase-type distributed random variables. In this example we perform an explicit comparison between asymptotic and exact results for the loss rate. Paper C deals with queues and insurance risk processes where a generic service time, respectively generic claim, has a truncated heavy-tailed distribution. We study the compound Poisson ruin probability (or, equivalently, the tail of the M/G/1 steady-state waiting time) numerically. Furthermore, we investigate the asymptotics of the asymptotic exponential decay rate as the truncation level tends to infinity in a more general truncated Lévy process set-up. Paper D is a sequel of Paper B. We consider a Lévy process reflected at 0 and $K$>0 and define the loss rate. The first step is to identify the loss rate, which is non-trivial in the Lévy process case. The technique we use is based on optional stopping of the Kella-Whitt martingale for the reflected process. Once the identification is performed, we derive asymptotics for the loss rate in the case of a light-tailed Lévy measure. Paper E is also a sequel of Paper B. We present an algorithm for simulating the loss rate for a reflected random walk. The algorithm is efficient in the sense of bounded relative error. Key words: many-server queues, quasi birth-death processes, Kella-Whitt martingale, optional stopping, heterogeneous servers, reflected random walks, loss rate, Lundberg's equation, Cramér-Lundberg approximation, Wiener-Hopf factorization, asymptotics, phase-type distributions, reflected Lévy processes, light tails, efficient simulation.
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| 4. |
- Kurbasic, Azra
(författare)
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Topics in Human Gene Mapping
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis is interdisciplinary between Mathematical Statistics, Genetics, and Medicine. It mainly consists of topics in mathematical modelling of the correlation of inheritance of genes and disease in a family, a method called linkage analysis. It is organized as follows. First, a short introduction with the relevant background is given and then four papers are included. The first paper discusses hypothesis testing of linkage of a disease gene to a certain position on the chromosome. The focus is on the choice of lod scores and its relation to p-values. The second paper is a result of collaboration with the research groups in Lund and Denmark in the effort to localize the gene responsible for a malignant melanoma. Here, the theory presented in the first paper is used. The third paper concerns modelling of complex diseases, i.e. diseases governed by genetic contribution from at least two loci. We have studied the contribution of a particular locus to increased risk of relatives compared with population prevalence. Relative risk is modelled as the product of the relative risk at the main locus and the relative risk due to genetic contribution from other loci and shared environmental effects. Additionally, we show how this relative risk is related to probabilities of allele sharing identical by descent at the main locus and the power to detect linkage. The last paper contributes to the development of the algorithms used in the linkage and family based association analysis. One of the most demanding issues in these analyses is how to calculate the inheritance distribution at a certain position on the chromosome. The well established algorithms are based on the assumption that the markers used in the studies are in linkage equilibrium (LE). However, today's marker data have markers in linkage disequilibrium (LD). We develop a novel hidden Markov model algorithm for association and linkage analysis when markers are in LD.
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| 5. |
- Wiktorsson, Magnus
(författare)
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Approximation of Infinitely Divisible Random Variables with Application to the Simulation of Stochastic Processes
- 2001
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis consists of four papers A, B, C and D. Paper A and B treats the simulation of stochastic differential equations (SDEs). The research presented therein was triggered by the fact that there were not any efficient implementations of the higher order methods for simulating SDEs. So in practice the higher order methods required at least the same amount of work as the Euler method to obtain a given mean square error. The faster convergence rate of the higher order methods requires the simulation of the so called iterated Itô integrals. In (A) we use a shot-noise type series representation of one iterated Itô integral. We split the series representation into a sum of n terms and a remainder term and show that the remainder term is asymptotically Gaussian as n goes to infinity. We provide an explicit coupling of the remainder a Gaussian random variable and show that this improves the mean square error by a factor n^½. In (B) we provide a multi-dimensional extension of the results in (A) as well as the not previously known simultaneous characteristic function of all iterated Itô integrals obtained the n pairing m independent Wiener processes. In (C) we study the simulation of type G Lévy processes. Recall that random variable is said to be of type G if it is a Gaussian variance mixture. We note that type G Lévy processes are subordinated Wiener processes. We use a series representation of the subordinator, a tail-sum approximation and obtain an explicit coupling between type G Lévy processes and the sum of a compound Poisson process and a scaled Wiener process. We calculate the mean integrated square error for this approximation. We examine the convergence of the scaled tail-sum process to its mean value function and provide a sufficient condition for this convergence. In paper (D) we utilise the coupling results from paper (C) to obtain approximations of stochastic integrals with respect to type G Lévy processes. Depending on the properties of the integrator we obtain either point-wise mean square error results or mean integrated square error results for the approximation. We also show that a stochastic time change representation of stochastic integrals can be used to obtain useful approximations.
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| 6. |
- Andersson, Fredrik K., et al.
(författare)
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The mathematics of internet search engines
- 2008
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Ingår i: Acta Applicandae Mathematicae - An International Survey Journal on Applying Mathematics and Mathematical Applications. - : Springer. - 0167-8019 .- 1572-9036. ; 104:2, s. 211-242
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Tidskriftsartikel (refereegranskat)abstract
- This article presents a survey of techniques for ranking results in search engines, with emphasis on link-based ranking methods and the PageRank algorithm. The problem of selecting, in relation to a user search query, the most relevant documents from an unstructured source such as the WWW is discussed in detail. The need for extending classical information retrieval techniques such as boolean searching and vector space models with link-based ranking methods is demonstrated. The PageRank algorithm is introduced, and its numerical and spectral properties are discussed. The article concludes with an alternative means of computing PageRank, along with some example applications of this new method.
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| 7. |
- Destouni, Georgia
(författare)
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Effects of water system uncertainties on effectiveness and efficiency of environmental policy and management
- 2007
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Ingår i: International Workshop on Uncertainty in Environmental Modelling, Earth Sciences Centre, Uppsala University, 28-30 March, 2007.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Increasing water pollution and deterioration of aquatic ecosystems are serious environmental problems. Modelling of pollutant transport, mass transfer, attenuation and downstream loading, from various pollutant sources, along different hydrological pathways, to water recipients, is needed for relevant decisions on effective allocation of pollution abatement measures. However, it is for various reasons (measurement and monitoring gaps; scientifically unresolved modelling disagreements; large, irregular and deterministically unquantifiable or unpredictable natural variability) both difficult and uncertain to quantify the real effects of upstream pollutant emission changes on downstream pollutant loads and concentrations. Furthermore, it may also be highly uncertain which pollutant load and concentration level reductions that are necessary and sufficient for achieving good water quality and ecosystem status in different water environments. These uncertainties may have large effects on pollution abatement that need to be recognized and handled in environmental policy. We discuss here how the water system uncertainty effects may be set in a wider decision making context, by quantifying their implications for both the probability of success and the economic performance of different environmental policies and management strategies.
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| 8. |
- Otani, Hiroki, et al.
(författare)
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Morphometric study on the characteristic external features of normal and abnormal human embryos
- 2008
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Ingår i: Congenit Anom Kyoto. - : Wiley. ; 48:1, s. 18-28
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Tidskriftsartikel (refereegranskat)abstract
- The embryonic period is characterized by organogenesis and accompanying dynamic changes in external features. The measurement of human embryos has been limited to whole body dimensions, such as crown-rump length. More detailed measurements would add quantitative information about these characteristic events and provide a better understanding of normal and abnormal embryonic development. In the present study, we defined axes, landmarks, and measurements for human embryos, and measured 250 externally normal human embryos at Carnegie stages 14-23 (6.5-29.3 mm in crown-rump length, approximately 5-8 weeks of estimated ovulation age) that were fixed in Bouin's solution and preserved in 10% formalin solution. The axes, landmarks, and measurements defined for human embryos are corresponding to those in human and primate fetuses. The whole body, head, face, and extremities were measured using a scale attached to a dissecting microscope. Axial length, head height plus ear-shoulder length plus trunk height, was designated as a new measurement of the whole body, which is comparable with crown-rump length. Approximate standards of these measurements were obtained. The ratios of some measurements to trunk height and between the different parts were also obtained, and several different developmental patterns were recognized. The reproducibility of each measurement was evaluated by measuring 50 specimens three times each at intervals of one or two months. As a pilot study for the application of the proposed measurements, 84 human embryos with external anomalies, including holoprosencephaly, anomalies of extremities, and pharyngeal arch anomalies, were measured using the same method, and a few tendencies characteristic to holoprosencephaly were noticed.
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| 9. |
- Johansson, Jan-Olof
(författare)
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Models of Surface Roughness with Applications in Paper Industry
- 2002
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis comprises general parametric models for surface roughness. The models can be used in several technical and natural applications but are here only applied to the micro-structure of paper. In that application, earlier models are generalized and new models introduced. The different models are related to the scale of the roughness and by using different approaches, different roughness properties are captured and put in a context, which is closely related to their practical use. The thesis consists of five papers. The first paper in the thesis treats a small scale roughness, which depends on the geometric properties of the cellulose fibers. In that paper, we formulate a parametric model whos parameters are connected to the fiber geomerty. We also introduce an estimator of the model parameters based on measurements in two orthogonal directions on the surface. The next paper aims to find a concise and, with repect to scale, generally applicable characterization of the surface roughness. We have found that the fractal dimension and the topothesy well meet these demands. Also based upon one-dimensional orthogonal measurement, we estimate these parameters and show that they can distinguish different paper qualities. Paper three describes a hierarchical model of the surface irregularities based on assumptions of Markov properties. In this model, two kind of scales are considered. A relative large scale comprising large clusters and a small scale close to the separate fibers. Descriptions and methods rely much on digital images analysis. Also this model distinguish different paper qualities but uses 8 parameters. In connection to this model, an investigation of different methods for finding global extremes is performed and reported in paper four. Newton's method and simulating annealing are compared and we found that simulated annealing sometimes can be used when Newton's method fails. However, Newton's method is generally the fastest one. Finally, we propose a measure of homogeneity in the last paper in the theses. We suggest here the two-dimensional kurtosis, which reflect the spatial homogeneity by using a single number.
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| 10. |
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| 11. |
- Tapani, Sofia, 1982, et al.
(författare)
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Three dimensional mathematical modelling of pronuclei migration for the mouse
- 2009
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Ingår i: Stereology and Image Analysis. Ecs10: Proceeding of the 10th European Conference of ISS., (V.Capasso et al. Ed.), The MIRIAM Project Series. - 9788874883103 ; 4, s. 1-6
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Konferensbidrag (refereegranskat)abstract
- It is still an open question when the orientation of the embryonic-abembryonic axis of the mouse embryo is laid down. The two most explicit symmetry breaking events for the egg are the extrusion of the second polar body and the sperm entry. The main question addressed in this paper is what happens between the sperm entering the egg and fusion of the two pronuclei. Orientation of the apposing pronuclei probably plays a decisive role in the polarity of the developing embryo. In order to shed some lights on this intriguing question, a mathematical model that describes the pronuclei dynamics have been constructed in the form of a stochastic differential equation. The model concerns pronuclei migration from the time of the sperm entry to the fusion and spatial orientation of this fusion. The methodology consists of using stacks of confocal microscopy time-lapse images of the pronuclei migration together with statistical methods to identify realistic parameters in the model. Given different angles between the sperm entry and the position of the second polar body, the final model is then used to produce distributions of orientations of the meeting positions between the pronuclei. However, the main result is the suggested model itself which describes the main features of the migration. The fitted model is based on two forces of attraction. Migration is directed towards the centre but also towards the other pronucleus. Parameter values corresponding to the size of these forces are estimated from data of both eggs treated with a microtubule inhibitor and untreated eggs. Simulations from the model with the different model parameters are accomplished and distributions of meeting positions are plotted. These simulated distributions could for instance be used as initial value distributions for future models of egg cleavage.
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| 12. |
- Lyrén, Per-Erik, 1976-
(författare)
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Prediction of academic performance by means of the Swedish scholastic assessment test
- 2008
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Ingår i: Scandinavian Journal of Educational Research. - : Taylor & Francis/Routledge. - 0031-3831 .- 1470-1170. ; 52:6, s. 565-581
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Tidskriftsartikel (refereegranskat)abstract
- This article reviews ten predictive validity studies of the Swedish Scholastic Assessment Test (SweSAT). A primary result is that the predictive validity of the SweSAT seems to be highly dependent upon the study programme being examined; that is, the predictive validity is better at some programmes than others. When compared with the upper-secondary school grade point average, the predictive validity of the SweSAT seems to be fairly good, but there are major differences between study programmes in this case as well. However, it is suggested that the validity of the results is to some extent threatened by methodological issues. A general conclusion is, therefore, that there is room for improving the test itself, as well as the way that predictive validity studies are carried out.
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| 13. |
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| 14. |
- Boqvist, Sofia, et al.
(författare)
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Sources of sporadic Yersinia enterocilitica infection in children in Sweden, 2004 : a case-control study
- 2009
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Ingår i: Epidemiology and Infection. - 0950-2688 .- 1469-4409. ; 137, s. 897-905
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Tidskriftsartikel (refereegranskat)abstract
- Young children account for a large proportion of reported Yersinia enterocolitica infections in Sweden with a high incidence compared with other gastrointestinal infections, such as salmonellosis and campylobacteriosis. A case-control study was conducted to investigate selected risk factors for domestic sporadic yersiniosis in children aged 0–6 years in Sweden. In total, 117 cases and 339 controls were included in the study. To minimize exclusion of observations due to missing data a multiple non-parametric imputation technique was used. The following risk factors were identified in the multivariate analysis : eating food prepared from raw pork products (OR 3.0, 95% CI 1.8–5.1) or treated sausage (OR 1.9, 95% CI 1.1–3.3), use of a baby’s dummy (OR 1.9, 95% CI 1.1–3.2) and contact with domestic animals (OR 2.0, 95% CI 1.2–3.4). We believe that the importance of Y. enterocolitica infection in children has been neglected and that results from this study can be used to develop preventive recommendations.
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| 15. |
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| 16. |
- Arvastson, Lars
(författare)
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Stochastic Modeling and Operational Optimization in District Heating Systems
- 2001
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Operation of a district heating system is accomplished via a sequence of decisions by the operators controlling the system. These decisions are based on expectations of conditions in the system that are not known at decision time. The operators could be helped by a decision support system that computes predictions of future system variables and suggests appropriate control actions given the available information. This thesis presents a new model that gives a both physical and stochastic description of a district heating system. The model describes both technical and economical information of the system that are important for the control decisions. It is easy to calculate predictions based on this model as well as performing simulations. The ambient temperature is the single most important explanatory variable for the heat demand in a district heating network. A model that can be used to calculate reliable temperature predictions are presented where the full advantage of both local measurements and forecasts from a meteorological institute are utilized. A heuristic approach to the operational optimization problem is presented and it is shown in simulations to be superior to a traditional control, based on a priority scheme. The operational optimization problem is a complex stochastic optimization problem and the heuristic approach gives a solution that can be calculate instantly. An online computer program, EnerPlan, is developed where the described models are used to calculate predictions and simulate alternative future scenarios. The program is currently used in the control room at the Heleneholm power plant in Malmö, Sweden.
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| 17. |
- Bogsjö, Klas
(författare)
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Road profile statistics relevant for vehicle fatigue
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Road profiles are studied from a vehicle fatigue point of view. A wide range of roads have been measured: from smooth motorways to very rough gravel roads. It is observed that the road profiles consist of irregular sections, which makes the stationary Gaussian model unsuitable (Paper A). In Paper B, a method for automatic identification of such irregularities is presented. It is verified that the irregular sections cause the major part of the fatigue damage induced in vehicles. Based on this result, a new single track model is proposed, which includes randomly shaped and located irregularities. In Paper C, an evaluation method of single track models is proposed. This evaluation method is extended to models of parallel tracks in Paper D. A new "parallel tracks" model is proposed and evaluated accordingly. In Paper E, the coherence between the parallel road tracks is studied. A simple one-parametric model is proposed for the coherence. In Paper F a new theoretical method to compute the expected vehicle fatigue damage caused by road irregularities is presented.
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| 18. |
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| 19. |
- Hagberg, Oskar
(författare)
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Asymptotic Expansions of Crossing Rates of Stationary Random Processes
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The crossing rate of a stationary random process is a valuble tool when studying crest hight distributions and maxima of sea level elevation. This thesis considers two approximation techinques for cases when the crossing rate cannot be exactly computed. Both techniques use an asymptotic expansion, and the first and second order terms in these expansions are given explicitly. Paper A describes how the rate of crossings is used to study crest hight distributions and maxima of sea level elevation and serves as a motivation for the subsequent three papers. Paper B and C both study an approximation technique proposed by Breitung (1988); Paper B considers the special case of the quadratic form of a Gaussian random process, while Paper C considers the general case that Breitung studied. Papers D treats the so- called Saddle point approximation of the crossing rate, allready studied informally by Butler et al (2003).
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| 20. |
- Olsson, Jimmy
(författare)
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On Bounds and Asymptotics of Sequential Monte Carlo Methods for Filtering, Smoothing, and Maximum Likelihood Estimation in State Space Models
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis is based on four papers (A-D) treating filtering, smoothing, and maximum likelihood (ML) estimation in general state space models using stochastic particle filters (also referred to as sequential Monte Carlo (SMC) methods). The aim of Paper A is to study the bias of Monte Carlo integration estimates produced by the so-called bootstrap particle filter. A bound on this bias which is inversely proportional to the number N of particles of the system is established. In addition, we refine the analysis by deriving the asymptotic bias as N tends to infinity and, under suitable mixing assumptions on the latent Markov model, a time uniform bound. In Paper B we consider ML estimation based on EM (Expectation-Maximization) methods. In this context, the key ingredient is the computation of smoothed sum functionals of the hidden states for given values of the model parameters. It has been observed by several authors that using standard SMC methods for this smoothing assignment may be unreliable for larger observations sizes. Thus we study a simple variant, based on forgetting ideas of the state space model dynamics, of the basic sequential smoothing approach which is transparent in terms of computation time and reduces the variability of the sum functional approximation. Under suitable regularity assumptions, it is shown that this modification indeed allows a tighter control of the L_p error and the bias of the approximation. To perform ML estimation in state space models, the log-likelihood function must be approximated. In Paper C we study such approximations based on particle filters, and in particular conditions for consistency and asymptotic normality of the corresponding approximate ML estimators. Numerical results illustrate the theory. Paper D is devoted to the study asymptotic properties of weighted particle samples produced by the so called two-stage sampling (TSS) particle filter, which is a generalization of the auxiliary particle filter proposed by Pitt and Shephard (1999). Besides establishing a central limit theorem (CLT) for smoothed particle estimates, we also derive bounds on the L_p error and bias of the same for a finite particle sample size. Setting out from the recursive formula for the asymptotic varianc of the CLT, we discuss some possible improvements of the TSS algorithm.
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| 21. |
- Rydén, Jesper
(författare)
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Statistical Analysis of Crests and Maxima in Gaussian Seas
- 2002
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- An important problem in ocean engineering is to find distributions for characteristic wave parameters. For wind-generated water waves at deep water, a Gaussian distribution for the wave-surface elevation is considered a reasonable model. Within the Gaussian assumption, extensions of Rice's formula can be applied to formulate explicit expressions for the distributions in the ergodic, or Palm, sense. This framework also allows for modelling with (Gaussian) random fields, which is one of the topics in this thesis. The explicit expressions need to be evaluated numerically which is possible to do once the covariance structure of the probabilistic model is known. In the papers of this thesis, a main theme is the joint distribution of wavelength and amplitude; this distribution is not easily obtained from measured time records. Distributions are deduced for different representations of the sea state, e.g. including directionality of waves. Where possible, comparisons with empirical field data are made and demonstrate good agreement. The derived joint distribution is applied to compute the distribution of the hogging-bending moment midships of a floating vessel. The problem of finding the distribution for high wave crests is also addressed, and its relation to wave groups is investigated. Further, the topic of filtering records is discussed. The rainflow filter, a non-linear filter used in fatigue analysis is investigated. An approximation in the frequency domain of the filter is proposed; it is found by a computer-intensive method involving i.a. spectral simulation. For the distribution of high crests, this linear approximation works well.
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| 22. |
- Ängquist, Lars
(författare)
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Pointwise and Genomewide Significance Calculations in Gene Mapping through Nonparametric Linkage Analysis: Theory, Algorithms and Applications
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In linkage analysis or, in a wider sense, gene mapping one searches for disease loci along a genome. This is done by observing so called marker genotypes (alleles) and phenotypes (affecteds/unaffecteds) of a pedigree set, i.e. a set of multigenerational families, in order to locate the loci corresponding to the underlying disease genes or, at least, to narrow down the interesting genome regions. In this context the key concept is the genetic inheritance of alleles with respect to the phenotype outcomes. A significant deviation from what is expected under random inheritance is taken as statistical evidence of existing genetic components suggested to be located at the loci giving significant results. In the thesis introduction we begin by outlining the needed genetical foundation of statistical genetics as well as some basic concepts, for instance, the process of allelic inheritance, the genetic disease model, the pedigree set, the inheritance vector and various types of genetic information. Next, we give an introduction to one-locus nonparametric linkage analysis focusing on significance calculations of nonparametric linkage (NPL) scores and, moreover, make some comments on the generalizations to two-locus procedures and the, related but contrasting, approach of parametric linkage analysis. In the third section we very briefly discuss some competing and complementary subfields within the context of statistical genetics and finally we put the papers included in this thesis into context by summarizing their content. Performing gene mapping-studies through whole, or substantial parts of, the genome gives rise to interpretational problems according to multiple testing. The theme of the thesis is how to calculate significance levels and powers in several contexts of such kind. In the first two papers one-locus NPL analysis, i.e. where one searches for one disease gene at a time, is considered. In Paper A existing analytical approximations of significance levels are improved and extended. The suggested formula is based on extreme-value theory for stochastic processes and a general link function between a continuous version of an arbitrary distribution function and the standard normal distribution function. In Paper B, in order to calculate significance levels, a new variant of weighted simulation for stochastic processes is developed. The method can handle complete as well as incomplete marker data and is very fast in relation to traditional methods of performing such simulations using Monte Carlo-based algorithms. The last two papers are directed towards two-locus NPL analysis, i.e. where one is interested in diseases with genetic components based on two distinct (nonsyntenic) disease genes. In Paper C significance levels and powers using unconditional two-locus analysis, i.e. where one simultaneously searches for two disease genes, are derived and discussed for homogeneous pedigree sets based on units of affected sib-pairs. Finally, in Paper D, a general approach for calculation of significance levels and powers in conditional two-locus analysis is developed. The conditional approach might be seen as a hybrid of one-locus and two-locus NPL analysis. Of central importance to this paper is the concept of noncentrality parameters, which basically is the expected value of the test statistic of interest, i.e. the NPL score, under a corresponding instance of the alternative hypotheses.
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| 23. |
- Häggkvist, Roland, et al.
(författare)
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Orthogonal Latin Rectangles
- 2008
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Ingår i: Combinatorics, probability & computing. - Cambridge : Cambridge University Press. - 0963-5483 .- 1469-2163. ; 17:4, s. 519-536
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Tidskriftsartikel (refereegranskat)abstract
- We use a greedy probabilistic method to prove that, for every ε > 0, every m × n Latin rectangle on n symbols has an orthogonal mate, where m = (1 − ε)n. That is, we show the existence of a second Latin rectangle such that no pair of the mn cells receives the same pair of symbols in the two rectangles.
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| 24. |
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Artificial Neural Networks in Medicine and Biology
- 2000
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Samlingsverk (redaktörskap) (övrigt vetenskapligt/konstnärligt)abstract
- This book contains the proceedings of ANNIMAB-1, the first international conference on artificial neural networks in medicine and biology. Comprising a selection of papers from leading researchers in the field, it summarises the state-of-the-art, analyses the relationship between ANN techniques and other available methods and points to possible future biomedical and medical uses of ANNs.
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| 25. |
- Almasri, Abdullah, 1965-, et al.
(författare)
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Wavelet Based Forecasting Approach, with Application
- 2009
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Ingår i: 2009 International Conference on Financial Theory and Engineering.
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Konferensbidrag (refereegranskat)abstract
- In this paper we outline a framework for forecasting using maximal overlap discrete wavelet transform (MODWT) based multiresoulution analysis (MRA). This framework has been applied for forecasting the tourism arrival series from Denmark to Norway. We compare forecasted values obtained from modeling the data in the time domain with the forecasted values from the wavelet domain using the traditional Box-Jenkins methodology. In both cases, diagnostic tests have been conducted to insure the specification of the model. The results have shown that the wavelet based forecasts outperforms the traditional Box-Jenkins approach in term of forecasts accuracy.
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