University of Groningen

About: University of Groningen is a education organization based out in Groningen, Groningen, Netherlands. It is known for research contribution in the topics: Population & Poison control. The organization has 36346 authors who have published 69116 publications receiving 2940370 citations. The organization is also known as: Rijksuniversiteit Groningen & RUG.

Introduction to Mathematical Systems Theory: A Behavioral Approach

Abstract: This is a book about modelling, analysis, and control of linear time-invariant systems. The book uses what is called the behavioral approach towards mathematical modelling. Thus a system is viewed as a dynamical relation between manifest and latent variables. The emphasis is on dynamical systems that are represented by systems of linear constant coefficient differential equations. In the first part of the book the structure of the set of trajectories that such dynamical systems generate is analyzed. Conditions are obtained for two systems of differential equations to be equivalent in the sense that they define the same behavior. It is further shown that the trajectories of such linear differential systems can be partitioned in free inputs and bound outputs. In addition the memory structure of the system is analyzed through state space models. The second part of the book is devoted to a number of important system properties, notably controllability, observability, and stability. An essential feature of using the behavioral approach is that it allows these and similar concepts to be introduced in a representation free manner. In the third part control problems are considered, more specifically stabilization and pole placement questions. The book is a textbook for advanced undergraduate or beginning graduate students in mathematics and engineering. It contains numerous exercises, including simulation problems, and examples, notably of mechanical systems and electrical circuits.

Cortical projection patterns of the medial septum-diagonal band complex

Abstract: A detailed analysis of the cortical projechns of the medial septum-diagonal band (MS/DR) complex was carried out by means of anterograde transport of Phaseolus vrilgaris leucoagglutinin (PHA-L). The tracer was injected iontophoretically into cell groups of the medial sept,um (MS) and the vertical and horizontal limbs of the diagonal band of Broca (VDR and HDB), and sections were processed immunohistochemically for the intra-axonally transported PHA-L. The labeled efferents showed remarkable differences in regional distribution in the cortical mantle dependent on the position of the injection site in the MSiDB complex, revealing a topographic organization of‘ the MSIDB-cortical projection. In brief, the lateral and intermediate aspects of the HDR, also referred to as the magnoc:cllular preoptic area, predominant.ly project to the olfactory nuclei and the lateral entorhinal cortex. The medial part of the HDR and adjacent caudal (angular) part of the VDB are characterized by widespread, abundant projections to medial mesolimbic, occipital, and lateral entorhinal cortices, olfactory bulb, and dorsal aspects of the subicular and hippocampal areas. Projections from the rostromedial part of the VDB and from the MS are preponderantly aimed at the entire hippocampal and retrohippocampal regions and t,o a lesser degree at the medial mesolirnbic cortex. Furthermore, the MS projections are subject to a clear mediolateral topographic arrangement, such that the lateral MS predominantly projects t,o the ventral/temporal aspects of the subicular complex and hippocampus and to the medial portion ofthe entorhinal cortex, whereas more medially located cells in the MS innervate more septal/dorsal parts of the hippocampal and subicular areas and more lat,eral parts of the entorhinal cortex. PHA-L filled axons have been observed to course through a number of pathways, i.e., the fimbria-fornix system, supracallosal stria, olfactory peduncle, and lateral piriform route (the latter two mainly by the HDB and caudal VDB). Generally, labeled projections were distributed throughout all cortical layers, although clear patterns of lamination were present in several target areas. The richly branching fibers were abundantly provided with both “boutons en passant” and terminal boutons. Both distribution and morphology of the labeled basal forebrain efferents in the prefrontal, cingulate, and occipital cortices closely resemble the distribution and morphology of the cholinergic innervation as revealed by immunohistochemical demonstration of choline acetyltransferase. In contrast, the labeled projections to the olfactory, hippocampal, subicular, and entorhinal areas showed a heterogeneous morphology. Here: the distribution of only the thin varicose projections resembled the distribution of cholinergic fibers.

Bayes factor approaches for testing interval null hypotheses

Abstract: Psychological theories are statements of constraint. The role of hypothesis testing in psychology is to test whether specific theoretical constraints hold in data. Bayesian statistics is well suited to the task of finding supporting evidence for constraint, because it allows for comparing evidence for 2 hypotheses against each another. One issue in hypothesis testing is that constraints may hold only approximately rather than exactly, and the reason for small deviations may be trivial or uninteresting. In the large-sample limit, these uninteresting, small deviations lead to the rejection of a useful constraint. In this article, we develop several Bayes factor 1-sample tests for the assessment of approximate equality and ordinal constraints. In these tests, the null hypothesis covers a small interval of non-0 but negligible effect sizes around 0. These Bayes factors are alternatives to previously developed Bayes factors, which do not allow for interval null hypotheses, and may especially prove useful to researchers who use statistical equivalence testing. To facilitate adoption of these Bayes factor tests, we provide easy-to-use software.

Contour detection based on nonclassical receptive field inhibition

Abstract: We propose a biologically motivated method, called nonclassical receptive field (non-CRF) inhibition (more generally, surround inhibition or suppression), to improve contour detection in machine vision. Non-CRF inhibition is exhibited by 80% of the orientation-selective neurons in the primary visual cortex of monkeys and has been shown to influence human visual perception as well. Essentially, the response of an edge detector at a certain point is suppressed by the responses of the operator in the region outside the supported area. We combine classical edge detection with isotropic and anisotropic inhibition, both of which have counterparts in biology. We also use a biologically motivated method (the Gabor energy operator) for edge detection. The resulting operator responds strongly to isolated lines, edges, and contours, but exhibits weak or no response to edges that are part of texture. We use natural images with associated ground truth contour maps to assess the performance of the proposed operator for detecting contours while suppressing texture edges. Our method enhances contour detection in cluttered visual scenes more effectively than classical edge detectors used in machine vision (Canny edge detector). Therefore, the proposed operator is more useful for contour-based object recognition tasks, such as shape comparison, than traditional edge detectors, which do not distinguish between contour and texture edges. Traditional edge detection algorithms can, however, also be extended with surround suppression. This study contributes also to the understanding of inhibitory mechanisms in biology.

Quasi-atomic auger-spectra in narrow-band metals

Abstract: In this Letter it is shown that quasiatomiclike Auger spectra in narrow-band metals are a direct result of electron correlation effects. It is shown that if the "on-site" Coulomb interaction is much larger than the one-electron-band width, the Auger spectrum consists of an intense narrow atomiclike peak together with a weak broad bandlike peak at higher kinetic energy. On the other hand, if the Coulomb interaction is small the Auger spectrum will resemble the convolution of the band density of states convoluted with itself.