Search results for "artifacts"
showing 10 items of 105 documents
Automated detection of patient movement during a CBCT scan based on the projection data.
2015
Objectives To develop an automated procedure to detect patient motion on the projection images acquired during a cone beam computed tomography (CBCT) scan and to evaluate the method's feasibility on small real-world CBCT images in relation to visual assessment. Methods Based on optical flow theory, software was developed using the sequence of the projection images of a CBCT machine for automated detection of patient motion. Averaged acceleration vectors were used as measurement data and compared with visual assessment of the projection images displayed as video. Seventy-nine CBCT data sets (small field-of-view: 40 mm) from our patient database were selected in a sequential fashion and evalu…
Samtidskunst i skolen : En studie som inviterer elever til en konseptuell workshopspraksis
2019
Masteroppgave kunstfag KF500 - Universitetet i Agder 2019 Both from the elementary school education and the professional life, I have gained insight and an experience basis for commenting on the subject of arts and crafts. There are often techniques and crafts that are in focus. I miss howthe subject to a greater extentcanchallengestudent`s in critical thinking, playful exploration and reflection, especially with regards to visual art. This master thesis focuses on theseperspectives for teaching in the subject arts and crafts, and discuss contemporary art's place intheschool. The thesis can be viewed as a post in the discourse about the new curriculumforarts and crafts, scheduledtobe comple…
Length of endodontic files measured in digital radiographs with and without noise-suppression filters: an ex-vivo study
2011
The aim of this study is to evaluate if theoretically possible edge shifts induced by noise-suppression filters potentially occur on objects found in digital radiographs. Most manufacturers carry out noise-suppression filtering of their images before they are displayed to the user. It is not usually possible for the user to disrupt the function of the filters. The use of these filters can lead to deletion of small image structures.K-files (ISO size 06, 08, 10 and 15) were placed in the root canals of 6 human teeth located in cadaver jaw segments. File tip positions were measured on original and filtered digital images by three observers. The file position was marked on each filtered image a…
EMG artifacts removal during electrical stimulation, a CWT based technique
2014
International audience; A technique of artifacts removal based on the continuous wavelet transform is presented. It uses common mother wavelets to find the temporal localization of stimulation artifacts on electromyogram (EMG) signal during an electrically evoked contraction of a muscle. This method can be used with standard stimulation pulse waveforms like monophasics or biphasics ones. It uses a histogram representation to find the best threshold to apply on the CWT domain. The algotithm is presented with Haar wavelet and then it is used with common wavelet famillies such as Daubechies or Symlets.
Online Detection and Removal of Eye Blink Artifacts from Electroencephalogram
2020
The most prominent type of artifact contaminating electroencephalogram (EEG)signals are the eyeblink (EB) artifacts, which could potentially lead tomisinterpretation of the EEG signal. Online detection and removal of eyeblink artifacts from EEG signals are essential in applications such a Brain-Computer Interfaces (BCI), neurofeedback and epilepsy diagnosis. In this thesis, algorithms that combine unsupervised eyeblink artifact detection (eADA) with enhanced Empirical Mode Decomposition (FastEMD) and Canonical Correlation Analysis (CCA) are proposed,i.e. FastEMD-CCA2 and FastCCA, to automatically identify eyeblink artifacts andremove them in an online setting. FastEMD-CCA2 and FastCCA have …
Intracranial measurement of current densities induced by transcranial magnetic stimulation in the human brain
2003
Transcranial magnetic stimulation (TMS) is a non-invasive technique that uses the principle of electromagnetic induction to generate currents in the brain via pulsed magnetic fields. The magnitude of such induced currents is unknown. In this study we measured the TMS induced current densities in a patient with implanted depth electrodes for epilepsy monitoring. A maximum current density of 12 microA/cm2 was recorded at a depth of 1 cm from scalp surface with the optimum stimulation orientation used in the experiment and an intensity of 7% of the maximal stimulator output. During TMS we recorded relative current variations under different stimulating coil orientations and at different points…
Compensation of missing wedge effects with sequential statistical reconstruction in electron tomography.
2014
Electron tomography (ET) of biological samples is used to study the organization and the structure of the whole cell and subcellular complexes in great detail. However, projections cannot be acquired over full tilt angle range with biological samples in electron microscopy. ET image reconstruction can be considered an ill-posed problem because of this missing information. This results in artifacts, seen as the loss of three-dimensional (3D) resolution in the reconstructed images. The goal of this study was to achieve isotropic resolution with a statistical reconstruction method, sequential maximum a posteriori expectation maximization (sMAP-EM), using no prior morphological knowledge about …
Effect of Motion Artifact on Digital Camera Based Heart Rate Measurement
2017
International audience; Depression is one of the most prevalent mental disorders, burdening many people world-wide. A system with the potential of serving as a decision support system is proposed, based on novel features extracted from facial expression geometry and speech, by interpreting non-verbal manifestations of depression. The proposed system has been tested both in gender independent and gender based modes, and with different fusion methods. The algorithms were evaluated for several combinations of parameters and classification schemes, on the dataset provided by the Audio/Visual Emotion Challenge of 2013 and 2014. The proposed framework achieved a precision of 94.8% for detecting p…
Insight on bacteria communities in outdoor bronze and marble artefacts in a changing environment
2022
Epilithic bacteria play a fundamental role in the conservation of cultural heritage (CH) materials. On stones, bacterial communities cause both degradation and bioprotection actions. Bronze biocorrosion in non-burial conditions is rarely studied. Only few studies have examined the relationship between bacteria communities and the chemical composi- tion of patinas (surface degradation layers). A better comprehension of bacterial communities growing on our CH is fundamental not only to understand the related decay mechanisms but also to foresee possible shifts in their compo- sition due to climate change. The present study aims at (1) characterizing bacterial communities on bronze andmarble s…
Confidence-based Somatic Mutation Evaluation and Prioritization
2012
Next generation sequencing (NGS) has enabled high throughput discovery of somatic mutations. Detection depends on experimental design, lab platforms, parameters and analysis algorithms. However, NGS-based somatic mutation detection is prone to erroneous calls, with reported validation rates near 54% and congruence between algorithms less than 50%. Here, we developed an algorithm to assign a single statistic, a false discovery rate (FDR), to each somatic mutation identified by NGS. This FDR confidence value accurately discriminates true mutations from erroneous calls. Using sequencing data generated from triplicate exome profiling of C57BL/6 mice and B16-F10 melanoma cells, we used the exist…