Search results for "algorithm."

World as Numbers : Living in an Algorithmic Culture

2016

There is a long tradition of trying to grasp the world around us in mathematical terms. From early man perceiving the motion of celestial bodies, to Pythagoras’ ‘celestial harmony’ and to Kepler’s and Newton’s laws of motion, calculations have provided ways to reduce the messy world of instances to a handful of mathematical formulae. Einstein’s Relativity Theory, and even more the quantum physics, complicated the situation, but still, even with random elements involved, the statistics could provide a model to understand the processes of the universe. When calculations grew ever more complex, and computers became necessary tools to deal with them, this lead to the idea of seeing the whole of…

2020

Introduction Adolescents’ physical activity (PA) behavior can be driven by several psychosocial determinants at the same time. Most analyses use a variable-based approach that examines relations between PA-related determinants and PA behavior on the between-person level. Using this approach, possible coexistences of different psychosocial determinants within one person cannot be examined. Therefore, by applying a person-oriented approach, this study examined a) which profiles regarding PA-related psychosocial variables typically occur in female sixth-graders, b) if these profiles deliver a self-consistent picture according to theoretical assumptions, and c) if the profiles contribute to the…

Sex-specific selection on energy metabolism - selection coefficients for winter survival

2010

Selection for different fitness optima between sexes is supposed to operate on several traits. As fitness-related traits are often energetically costly, selection should also act directly on the energetics of individuals. However, efforts to examine the relationship between fitness and components of the energy budget are surprisingly scarce. We investigated the effects of basal metabolic rate (BMR, the minimum energy required for basic life functions) and body condition on long-term survival (8 winter months) with manipulated densities in enclosed populations of bank voles (Myodes glareolus). Here, we show that survival selection on BMR was clearly sex-specific but density-independent. Both…

Awareness and partitional information structures

1994

This is the first of two papers where we present a formal model of unawareness. We contrast unawareness with certainty and uncertainty. A subject is certain of something when he knows that thing; he is uncertain when he does not know it, but he knows he does not: he is consciously uncertain. On the other hand, he is unaware of something when he does not know it, and he does not know he does not know, and so on ad infinitum: he does not perceive, does not have in mind, the object of knowledge. The opposite of unawareness is awareness, which includes certainty and uncertainty. This paper has three main purposes. First, we formalize the concept of awareness, and introduce a symmetry axiom whic…

Spurious source generation in mapping from noisy phase-self-calibrated data

2008

Phase self-calibration (or selfcal) is an algorithm often used in the calibration of interferometric observations in astronomy. Although a powerful tool, this algorithm presents strong limitations when applied to data with a low signal-to-noise ratio. We analyze the artifacts that the phase selfcal algorithm produces when applied to extremely noisy data. We show how the phase selfcal may generate a spurious source in the sky from a distribution of completely random visibilities. This spurious source is indistinguishable from a real one. We numerically and analytically compute the relationship between the maximum spurious flux density generated by selfcal from noise and the particulars of th…

Personality and musical preference using social-tagging in excerpt-selection.

2017

Music preference has been related to individual differences like social identity, cognitive style, and personality, but quantifying music preference can be a challenge. Self-report measures may be too presumptive of shared genre definitions between listeners, while listener ratings of expert-selected music may fail to reflect typical listeners’ genre boundaries. The current study aims to address this by using a social-tagging approach to select music for studying preference. In this study, 2,407 tracks were collected and subsampled from the Last.fm social-tagging service and the EchoNest platform based on attributes such as genre, tempo, and danceability. The set was further subsampled acco…

Global Chronic Total Occlusion Crossing Algorithm

2021

© 2021 The Authors. Published by Elsevier on behalf of the American College of Cardiology Foundation. This is an open access article under the CC By-NC-ND License (http://creativecommons.org/licenses/by-nc-nd/4)

A fourier-based algorithm for micro-calcification enhancement in mammographic images

2008

Breast cancer is the most widespread cancer in women in the world; it manifests mostly in two forms: microcalcifications and massive lesions. These two forms differ in density, size, shape and number. Consequently, there are two different kinds of mammographic CAD algorithms: those for microcalcifications detection, and those for massive lesions detection. The microcalcifications detection is a hard task, since they are quite small and often poorly contrasted against the background, especially in images affected by digitization noise. In a CAD system the ROI Hunter plays an important role, because missed microcalcifications at this level are definitely lost. For this reason, highlighting me…

Kinetic analysis of functional images: The case for a practical approach to performance prediction

1999

We present the first parallel medical application for the analysis of dynamic positron emission tomography (PET) images together with a practical performance model. The parallel application may improve the diagnosis for a patient (e. g. in epilepsy surgery) because it enables the fast computation of parametric images on a pixed level as opposed to the traditionally used region of interest (ROI) approach which is applied to determine an average parametric value for a particular anatomic region of the brain. We derive the performance model from the application context and show its relation to abstract machine models. We demonstrate the accuracy of the model to predict the runtime of the appli…

Towards data-driven medical imaging using natural language processing in patients with suspected urolithiasis.

2020

Abstract Objective The majority of radiological reports are still written as free text and lack structure. Further evaluation of free-text reports is difficult to achieve without a great deal of manual effort, and is not possible in everyday clinical practice. This study aims to automatically capture clinical information and positive hit rates from narrative radiological reports of suspected urolithiasis using natural language processing (NLP). Methods Narrative reports of low dose computed tomography (CT) of the retroperitoneum from April 2016 to July 2018 (n = 1714) were analyzed using NLP. These free-text reports were automatically structured based on RadLex concepts. Manual feedback was…