Search results for "Methods"

Multicenter stability of diffusion tensor imaging measures: a European clinical and physical phantom study.

2011

Diffusion tensor imaging (DTI) detects white matter damage in neuro-psychiatric disorders, but data on reliability of DTI measures across more than two scanners are still missing. In this study we assessed multicenter reproducibility of DTI acquisitions based on a physical phantom as well as brain scans across 16 scanners. In addition, we performed DTI scans in a group of 26 patients with clinically probable Alzheimer's disease (AD) and 12 healthy elderly controls at one single center. We determined the variability of fractional anisotropy (FA) measures using manually placed regions of interest as well as automated tract based spatial statistics and deformation based analysis. The coefficie…

Reflections on Connectionist Modeling

2018

International audience

The Psychology of Thinking in Creating AI

2021

The broad-scale emergence of AI in industry calls forth basic questions in terms of the knowledge bases and approaches relevant for its design. Engineering design has been mainly developed for electromechanical artifacts. In practice, this has meant that the scientific knowledge required for creating technical artifacts such as engines, cars, ships, cranes, telephones, radios, TVs, and simple data processing units has been natural science. However, one cannot find intelligent processes by means of physics and chemistry. Natural scientific phenomena follow their deterministic laws, but intelligence is based on selection and decision processes. The conceptual landscape of natural science is o…

Teaching types with a cognitively effective worked example format

2015

AbstractTeaching functional programming as a second programming paradigm is often difficult as students can have strong preconceptions about programming. When most of these preconceived ideas fail to be confirmed, functional programming may be seen as an unnecessarily difficult topic. A typical topic that causes such difficulties is the language of types employed by many modern functional languages. In this paper, we focus on addressing this difficulty through the use of step-by-step calculations of type expressions. The outcome of the study is an elaboration of a worked example format and a methodical approach for teaching types to beginner functional programmers.

Effect of inter-crystal scatter on estimation methods for random coincidences and subsequent correction.

2008

Random coincidences can contribute substantially to the background in positron emission tomography (PET). Several estimation methods are being used for correcting them. The goal of this study was to investigate the validity of techniques for random coincidence estimation, with various low-energy thresholds (LETs). Simulated singles list-mode data of the MADPET-II small animal PET scanner were used as input. The simulations have been performed using the GATE simulation toolkit. Several sources with different geometries have been employed. We evaluated the number of random events using three methods: delayed window (DW), singles rate (SR) and time histogram fitting (TH). Since the GATE simula…

A Generalised RBF Finite Difference Approach to Solve Nonlinear Heat Conduction Problems on Unstructured Datasets

2011

Radial Basis Functions have traditionally been used to provide a continuous interpolation of scattered data sets. However, this interpolation also allows for the reconstruction of partial derivatives throughout the solution field, which can then be used to drive the solution of a partial differential equation. Since the interpolation takes place on a scattered dataset with no local connectivity, the solution is essentially meshless. RBF-based methods have been successfully used to solve a wide variety of PDEs in this fashion. Such full-domain RBF methods are highly flexible and can exhibit spectral convergence rates Madych & Nelson (1990). However, in their traditional implementation the fu…

Probing dynamics of dense suspensions: three-dimensional cross-correlation technique

1997

We describe the realization of a novel three-dimensional (3D) cross-correlation scheme, which provides the possibility to measure dynamic structure factors of highly concentrated colloidal samples without contributions of multiply scattered light. The apparatus is easier to align and more compact than the two-colour cross-correlation apparatus, which is commercially available. This should make the 3D cross-correlation set-up more convenient for routine applications, for example in industrial laboratories. We describe the set-up and discuss some special features of the optical components.

Light scattering - diagnostic methods for colloidal dispersions

1993

Abstract The increasing demand from the colloid research community for quick and noninvasive experimental techniques as well as the rapid progress of modern optics and electronics have led to a considerable expansion in the field of light scattering. This review introduces the basic concepts with some emphasis on novel approaches like the study of interacting particle systems, multiple scattering techniques, and non ergodic samples. Particular attention is then devoted to recent experimental progress towards more compact and rugged instruments.

Patterns of rapid weight loss in elite wrestlers

The aim of this study was to examine the methodology used for RWL and to compare different methods and source of influence practiced by various wrestling styles. The obtained results suggest that 67% of athletes had previously lost weight to compete. The wrestling coach represents the most influential person in terms of RWL strategies. The most frequently used methods were increased exercise, gradual dieting, training in heated room and sauna, for all competitors. The education of wrestling coaches is necessary in order to control and decrease the negative impact of RWL.

Pattern Matching and Pattern Discovery Algorithms for Protein Topologies

2001

We describe algorithms for pattern-matching and pattern-learning in TOPS diagrams (formal descriptions of protein topologies). These problems can be reduced to checking for subgraph isomorphism and finding maximal common subgraphs in a restricted class of ordered graphs. We have developed a subgraph isomorphism algorithm for ordered graphs, which performs well on the given set of data. The maximal common subgraph problem then is solved by repeated subgraph extension and checking for isomorphisms. Despite its apparent inefficiency, this approach yields an algorithm with time complexity proportional to the number of graphs in the input set and is still practical on the given set of data. As a…