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Sample records for lines useless artifacts

  1. Lung cancer cell lines: Useless artifacts or invaluable tools for medical science?

    Science.gov (United States)

    Gazdar, Adi F; Gao, Boning; Minna, John D

    2010-06-01

    Multiple cell lines (estimated at 300-400) have been established from human small cell (SCLC) and non-small cell lung cancers (NSCLC). These cell lines have been widely dispersed to and used by the scientific community worldwide, with over 8000 citations resulting from their study. However, there remains considerable skepticism on the part of the scientific community as to the validity of research resulting from their use. These questions center around the genomic instability of cultured cells, lack of differentiation of cultured cells and absence of stromal-vascular-inflammatory cell compartments. In this report we discuss the advantages and disadvantages of the use of cell lines, address the issues of instability and lack of differentiation. Perhaps the most important finding is that every important, recurrent genetic and epigenetic change including gene mutations, deletions, amplifications, translocations and methylation-induced gene silencing found in tumors has been identified in cell lines and vice versa. These "driver mutations" represented in cell lines offer opportunities for biological characterization and application to translational research. Another potential shortcoming of cell lines is the difficulty of studying multistage pathogenesis in vitro. To overcome this problem, we have developed cultures from central and peripheral airways that serve as models for the multistage pathogenesis of tumors arising in these two very different compartments. Finally the issue of cell line contamination must be addressed and safeguarded against. A full understanding of the advantages and shortcomings of cell lines is required for the investigator to derive the maximum benefit from their use. Copyright 2010 Elsevier Ireland Ltd. All rights reserved.

  2. Artifacts

    Science.gov (United States)

    Harris, Samantha

    2009-01-01

    NASA Headquarters sent a list of items to KSC that were deemed potential artifacts. These items played arole in the Shuttle Program's development and maintenance. Because these items are national assets, many are of interest to museums, schools, other government entities, etc. upon the Space Shuttle's retirement. The list contains over 500 items. All of these items need to be located, photographed, and catalogued with accompanying specific data that needs to be gathered. Initial research suggests that this is a time, labor, and cost intensive project. The purpose of my project was to focus on 20-60 of these 500 items, gather the necessary data, and compile them in a way that can be added to by other users when/if the project goes into full effect.

  3. Removal of line artifacts on mesh boundary in computer generated hologram by mesh phase matching.

    Science.gov (United States)

    Park, Jae-Hyeung; Yeom, Han-Ju; Kim, Hee-Jae; Zhang, HuiJun; Li, BoNi; Ji, Yeong-Min; Kim, Sang-Hoo

    2015-03-23

    Mesh-based computer generated hologram enables realistic and efficient representation of three-dimensional scene. However, the dark line artifacts on the boundary between neighboring meshes are frequently observed, degrading the quality of the reconstruction. In this paper, we propose a simple technique to remove the dark line artifacts by matching the phase on the boundary of neighboring meshes. The feasibility of the proposed method is confirmed by the numerical and optical reconstruction of the generated hologram.

  4. The usefulness of useless knowledge

    CERN Document Server

    Flexner, Abraham

    2017-01-01

    A short, provocative book about why "useless" science often leads to humanity's greatest technological breakthroughs. A forty-year tightening of funding for scientific research has meant that resources are increasingly directed toward applied or practical outcomes, with the intent of creating products of immediate value. In such a scenario, it makes sense to focus on the most identifiable and urgent problems, right? Actually, it doesn't. In his classic essay "The Usefulness of Useless Knowledge," Abraham Flexner, the founding director of the Institute for Advanced Study in Princeton and the man who helped bring Albert Einstein to the United States, describes a great paradox of scientific research. The search for answers to deep questions, motivated solely by curiosity and without concern for applications, often leads not only to the greatest scientific discoveries but also to the most revolutionary technological breakthroughs. In short, no quantum mechanics, no computer chips. This brief book includes Flexn...

  5. Novel Automatic Detection of Pleura and B-lines (Comet-Tail Artifacts) on In-Vivo Lung Ultrasound Scans

    DEFF Research Database (Denmark)

    Moshavegh, Ramin; Hansen, Kristoffer Lindskov; Møller-Sørensen, Hasse

    2016-01-01

    This paper presents a novel automatic method for detection of B-lines (comet-tail artifacts) in lung ultrasound scans. B-lines are the most commonly used artifacts for analyzing the pulmonary edema. They appear as laser-like vertical beams, which arise from the pleural line and spread down without...... images. The pleural line is first segmented on each image and then the B-line artifacts spreading down from the pleural line are detected and overlayed on the image. The resulting 300 images showed that the mean lateral distance between B-lines detected on images acquired from patients decreased by 20...

  6. The art of useless suffering.

    Science.gov (United States)

    Edgar, Andrew

    2007-12-01

    The purpose of this paper is to explore the role that modernism in the arts might have in articulating the uselessness and incomprehensibility of physical and mental suffering. It is argued that the experience of illness is frequently resistant to interpretation, and as such, it will be suggested, to conventional forms of artistic expression and communication. Conventional narratives, and other beautiful or conventionally expressive aesthetic structures, that presuppose the possibility and desirability of an harmonious and meaningful resolution to conflicts and tensions, may fundamentally misrepresent the patient's experience. By drawing on the work of Emmanuel Levinas (on useless suffering) and the aesthetic theories of Nietzsche and T. W. Adorno, it will be argued first that a faith in the possibility of harmonious resolution of suffering is misplaced and does violence to the experience of suffering. Second, it will be argued that the expression of suffering lies not in finding words, images or sounds that communicate the experience of that suffering to others, but rather in the persistent and radical disruption of any illusion of meaning and coherence that might be imposed upon the experience, so that the very possibility of communication is also disrupted.

  7. Towards the semantic characterization of digital representations of architectural artifacts: programmatic lines of research

    Directory of Open Access Journals (Sweden)

    Livio De Luca

    2011-12-01

    Full Text Available These programmatic lines of research, at the intersection between the disciplinary fields of the built heritage documentation and the information and communication technologies, aims to define a set of technical elements concerning the development of information systems at an architectural scale integrating it into methodological reflections related to scientific issues concerning the study of historic buildings. Three main aspects are integrated in a cross approach. First, the definition of protocols for acquisition, processing and semantic structuring of digital representations of architectural artifacts. Secondly, the identification of solutions for interconnecting multiple representation systems at various scales. Finally, the definition of new way for the comparative analysis of architectural artifacts based on dimensional, morphological and semantic criteria.

  8. WE-G-204-06: Grid-Line Artifact Minimization for High Resolution Detectors Using Iterative Residual Scatter Correction

    Energy Technology Data Exchange (ETDEWEB)

    Rana, R; Bednarek, D; Rudin, S [Toshiba Stroke & Vascular Research Center, University at Buffalo, Buffalo, NY (United States)

    2015-06-15

    Purpose: Anti-scatter grid-line artifacts are more prominent for high-resolution x-ray detectors since the fraction of a pixel blocked by the grid septa is large. Direct logarithmic subtraction of the artifact pattern is limited by residual scattered radiation and we investigate an iterative method for scatter correction. Methods: A stationary Smit-Rοntgen anti-scatter grid was used with a high resolution Dexela 1207 CMOS X-ray detector (75 µm pixel size) to image an artery block (Nuclear Associates, Model 76-705) placed within a uniform head equivalent phantom as the scattering source. The image of the phantom was divided by a flat-field image obtained without scatter but with the grid to eliminate grid-line artifacts. Constant scatter values were subtracted from the phantom image before dividing by the averaged flat-field-with-grid image. The standard deviation of pixel values for a fixed region of the resultant images with different subtracted scatter values provided a measure of the remaining grid-line artifacts. Results: A plot of the standard deviation of image pixel values versus the subtracted scatter value shows that the image structure noise reaches a minimum before going up again as the scatter value is increased. This minimum corresponds to a minimization of the grid-line artifacts as demonstrated in line profile plots obtained through each of the images perpendicular to the grid lines. Artifact-free images of the artery block were obtained with the optimal scatter value obtained by this iterative approach. Conclusion: Residual scatter subtraction can provide improved grid-line artifact elimination when using the flat-field with grid “subtraction” technique. The standard deviation of image pixel values can be used to determine the optimal scatter value to subtract to obtain a minimization of grid line artifacts with high resolution x-ray imaging detectors. This study was supported by NIH Grant R01EB002873 and an equipment grant from Toshiba

  9. Artifacts in digital radiography

    Energy Technology Data Exchange (ETDEWEB)

    Min, Jung Whan [Dept. of Radiological Technology, Shin Gu University, Sungnam (Korea, Republic of); Kim, Jung Min [Dept. of Radiological Technology, Korea University, Seoul (Korea, Republic of); Jeong, Hoi Woun [Dept. of Radiological Technology, Beakseok Culture University, Cheonan (Korea, Republic of)

    2015-12-15

    Digital Radiography is a big part of diagnostic radiology. Because uncorrected digital radiography image supported false effect of Patient’s health care. We must be manage the correct digital radiography image. Thus, the artifact images can have effect to make a wrong diagnosis. We report types of occurrence by analyzing the artifacts that occurs in digital radiography system. We had collected the artifacts occurred in digital radiography system of general hospital from 2007 to 2014. The collected data had analyzed and then had categorize as the occurred causes. The artifacts could be categorized by hardware artifacts, software artifacts, operating errors, system artifacts, and others. Hardware artifact from a Ghost artifact that is caused by lag effect occurred most frequently. The others cases are the artifacts caused by RF noise and foreign body in equipments. Software artifacts are many different types of reasons. The uncorrected processing artifacts and the image processing error artifacts occurred most frequently. Exposure data recognize (EDR) error artifacts, the processing error of commissural line, and etc., the software artifacts were caused by various reasons. Operating artifacts were caused when the user did not have the full understanding of the digital medical image system. System artifacts had appeared the error due to DICOM header information and the compression algorithm. The obvious artifacts should be re-examined, and it could result in increasing the exposure dose of the patient. The unclear artifact leads to a wrong diagnosis and added examination. The ability to correctly determine artifact are required. We have to reduce the artifact occurrences by understanding its characteristic and providing sustainable education as well as the maintenance of the equipments.

  10. Quantitative methods in psychology: inevitable and useless

    Directory of Open Access Journals (Sweden)

    Aaro Toomela

    2010-07-01

    Full Text Available Science begins with the question, what do I want to know? Science becomes science, however, only when this question is justified and the appropriate methodology is chosen for answering the research question. Research question should precede the other questions; methods should be chosen according to the research question and not vice versa. Modern quantitative psychology has accepted method as primary; research questions are adjusted to the methods. For understanding thinking in modern quantitative psychology, two epistemologies should be distinguished: structural-systemic that is based on Aristotelian thinking, and associative-quantitative that is based on Cartesian-Humean thinking. The first aims at understanding the structure that underlies the studied processes; the second looks for identification of cause-effect relationships between the events with no possible access to the understanding of the structures that underlie the processes. Quantitative methodology in particular as well as mathematical psychology in general, is useless for answering questions about structures and processes that underlie observed behaviors. Nevertheless, quantitative science is almost inevitable in a situation where the systemic-structural basis of behavior is not well understood; all sorts of applied decisions can be made on the basis of quantitative studies. In order to proceed, psychology should study structures; methodologically, constructive experiments should be added to observations and analytic experiments.

  11. MRI Artifacts

    Directory of Open Access Journals (Sweden)

    Abed Al Nasser Assi

    2009-12-01

    Full Text Available   "nMagnetic resonance imaging (MRI has become more and more frequently used in medical imaging diagnostic in recent years. Radiologists and technicians working at these systems are relatively often confronted with image artifacts related to the radiowave with strong magnetic in the scanner. Many artifacts may be corrected or modulated through an understanding of their cause. This requires familiarity with scanner design; theory of operation; and image acquisition. The purpose of this review article is to present the most relevant artifacts that arise in MRI scanner, to provide some physical background on the formation of artifacts, and to suggest strategies to reduce or avoid these artifacts. The most frequent artifacts that can occur during MRI scanning are Motion related artifacts; Para-magnetic artifacts; Phase Wrap artifacts; Frequency artifacts; Susceptibility artifacts; Clipping artefact; Chemical Shift artifact and "Zebra" artefact .    "n  

  12. Scatter estimation and removal of anti-scatter grid-line artifacts from anthropomorphic head phantom images taken with a high resolution image detector

    Science.gov (United States)

    Rana, R.; Jain, A.; Shankar, A.; Bednarek, D. R.; Rudin, S.

    2016-03-01

    In radiography, one of the best methods to eliminate image-degrading scatter radiation is the use of anti-scatter grids. However, with high-resolution dynamic imaging detectors, stationary anti-scatter grids can leave grid-line shadows and moiré patterns on the image, depending upon the line density of the grid and the sampling frequency of the x-ray detector. Such artifacts degrade the image quality and may mask small but important details such as small vessels and interventional device features. Appearance of these artifacts becomes increasingly severe as the detector spatial resolution is improved. We have previously demonstrated that, to remove these artifacts by dividing out a reference grid image, one must first subtract the residual scatter that penetrates the grid; however, for objects with anatomic structure, scatter varies throughout the FOV and a spatially differing amount of scatter must be subtracted. In this study, a standard stationary Smit-Rontgen X-ray grid (line density - 70 lines/cm, grid ratio - 13:1) was used with a high-resolution CMOS detector, the Dexela 1207 (pixel size - 75 micron) to image anthropomorphic head phantoms. For a 15 x 15cm FOV, scatter profiles of the anthropomorphic head phantoms were estimated then iteratively modified to minimize the structured noise due to the varying grid-line artifacts across the FOV. Images of the anthropomorphic head phantoms taken with the grid, before and after the corrections, were compared demonstrating almost total elimination of the artifact over the full FOV. Hence, with proper computational tools, antiscatter grid artifacts can be corrected, even during dynamic sequences.

  13. Artifacts in field free line magnetic particle imaging in the presence of inhomogeneous and nonlinear magnetic fields

    Directory of Open Access Journals (Sweden)

    Medimagh Hanne

    2015-09-01

    Full Text Available Introduction: Magnetic Particle Imaging (MPI is an emerging medical imaging modality that detects super-paramagnetic particles exploiting their nonlinear magnetization response. Spatial encoding can be realized using a Field Free Line (FFL, which is generated, rotated and translated through the Field of View (FOV using a combination of magnetic gradient fields and homogeneous excitation fields. When scaling up systems and/or enlarging the FOV in comparison to the scanner bore, ensuring homogeneity and linearity of the magnetic fields becomes challenging. The present contribution describes the first comprehensive, systematic study on the influence of magnetic field imperfections in FFL MPI. Methods: In a simulation study, 14 different FFL scanner setups have been examined. Starting from an ideal scanner using perfect magnetic fields, defined imperfections have been introduced in a range of configurations (nonlinear gradient fields, inhomogeneous excitation fields, or inhomogeneous receive fields, or a combination thereof. In the first part of the study, the voltage induced in the receive channels parallel and perpendicular to the FFL translation have been studied for discrete FFL angles. In the second part, an imaging process has been simulated comparing different image reconstruction approaches. Results: The induced voltage signals demonstrate illustratively the effect of the magnetic field imperfections. In images reconstructed using a Radon-based approach, the magnetic field imperfections lead to pronounced artifacts, especially if a deconvolution using the point spread function is performed. In images reconstructed using a system function based approach, variations in local image quality become visible. Conclusion: For Radon-based image reconstruction in FFL MPI in the presence of inhomogeneous and nonlinear magnetic fields, artifact correction methods will have to be developed. In this regard, a first approach has recently been presented by

  14. Camera artifacts in IUE spectra

    Science.gov (United States)

    Bruegman, O. W.; Crenshaw, D. M.

    1994-01-01

    This study of emission line mimicking features in the IUE cameras has produced an atlas of artifiacts in high-dispersion images with an accompanying table of prominent artifacts and a table of prominent artifacts in the raw images along with a medium image of the sky background for each IUE camera.

  15. Cleaning MEG artifacts using external cues.

    Science.gov (United States)

    Tal, I; Abeles, M

    2013-07-15

    Using EEG, ECoG, MEG, and microelectrodes to record brain activity is prone to multiple artifacts. The main power line (mains line), video equipment, mechanical vibrations and activities outside the brain are the most common sources of artifacts. MEG amplitudes are low, and even small artifacts distort recordings. In this study, we show how these artifacts can be efficiently removed by recording external cues during MEG recordings. These external cues are subsequently used to register the precise times or spectra of the artifacts. The results indicate that these procedures preserve both the spectra and the time domain wave-shapes of the neuromagnetic signal, while successfully reducing the contribution of the artifacts to the target signals without reducing the rank of the data.

  16. Artifacts as Conventional Objects

    Science.gov (United States)

    Siegel, Deborah R.; Callanan, Maureen A.

    2007-01-01

    What underlies children's understanding of artifacts? Studies suggest that beginning around age 7, people reason about artifacts in terms of the inventor's purpose--termed "the design stance." Our two studies emphasize another component of artifact understanding--the cultural nature of artifacts--by demonstrating people's sensitivity to an…

  17. Ultrasound Artifacts - Part 1.

    Science.gov (United States)

    Bönhof, J A

    2016-04-01

    Knowledge of artifacts is essential for the competent use of ultrasound. Artifacts are method-based and should be differentiated from image errors of another genesis. They are logical and occur because the conditions required for image generation do not fully correspond to the reality. Artifacts occur due to disregard of the true dimensions of sound lobes (slice-thickness artifacts and bow artifacts, range ambiguities) and due to different types of mirroring with different appearances. There are also comet-tail-like artifacts such as comet-tail and ring-down artifacts.

  18. PET/CT Artifacts

    OpenAIRE

    Blodgett, Todd M.; Mehta, Ajeet S.; Mehta, Amar S.; Laymon, Charles M; Carney, Jonathan; Townsend, David W.

    2011-01-01

    There are several artifacts encountered in PET/CT imaging, including attenuation correction (AC) artifacts associated with using CT for attenuation correction. Several artifacts can mimic a 2-deoxy-2-[18F] fluoro-D-glucose (FDG) avid malignant lesions and therefore recognition of these artifacts is clinically relevant. Our goal was to identify and characterize these artifacts and also discuss some protocol variables that may affect image quality in PET/CT.

  19. Dynamics in artifact ecologies

    DEFF Research Database (Denmark)

    Bødker, Susanne; Klokmose, Clemens Nylandsted

    2012-01-01

    We increasingly interact with multiple interactive artifacts with overlapping capabilities during our daily activities. It has previously been shown that the use of an interactive artifact cannot be understood in isolation, but artifacts must be understood as part of an artifact ecology, where ar...... in artifact ecologies cannot be understood as static, instead they evolve dynamically over time. We provide activity theory-based concepts to explain these dynamics....

  20. Mesoscale hybrid calibration artifact

    Science.gov (United States)

    Tran, Hy D.; Claudet, Andre A.; Oliver, Andrew D.

    2010-09-07

    A mesoscale calibration artifact, also called a hybrid artifact, suitable for hybrid dimensional measurement and the method for make the artifact. The hybrid artifact has structural characteristics that make it suitable for dimensional measurement in both vision-based systems and touch-probe-based systems. The hybrid artifact employs the intersection of bulk-micromachined planes to fabricate edges that are sharp to the nanometer level and intersecting planes with crystal-lattice-defined angles.

  1. Breast Imaging Artifacts.

    Science.gov (United States)

    Odle, Teresa G

    2015-01-01

    Artifacts appear on breast images for a number of reasons. Radiologic technologists play an important role in identifying artifacts that can help or hinder breast cancer diagnosis and in minimizing artifacts that degrade image quality. This article describes various artifacts that occur in breast imaging, along with their causes. The article focuses on artifacts in mammography, with a heavy emphasis on digital mammography, and on magnetic resonance imaging of the breast. Artifacts in ultrasonography of the breast, digital breast tomosynthesis, and positron emission mammography also are discussed.

  2. Artifact removal in physiological signals--practices and possibilities.

    Science.gov (United States)

    Sweeney, Kevin T; Ward, Tomás E; McLoone, Seán F

    2012-05-01

    The combination of reducing birth rate and increasing life expectancy continues to drive the demographic shift toward an aging population. This, in turn, places an ever-increasing burden on healthcare due to the increasing prevalence of patients with chronic illnesses and the reducing income-generating population base needed to sustain them. The need to urgently address this healthcare "time bomb" has accelerated the growth in ubiquitous, pervasive, distributed healthcare technologies. The current move from hospital-centric healthcare toward in-home health assessment is aimed at alleviating the burden on healthcare professionals, the health care system and caregivers. This shift will also further increase the comfort for the patient. Advances in signal acquisition, data storage and communication provide for the collection of reliable and useful in-home physiological data. Artifacts, arising from environmental, experimental and physiological factors, degrade signal quality and render the affected part of the signal useless. The magnitude and frequency of these artifacts significantly increases when data collection is moved from the clinic into the home. Signal processing advances have brought about significant improvement in artifact removal over the past few years. This paper reviews the physiological signals most likely to be recorded in the home, documenting the artifacts which occur most frequently and which have the largest degrading effect. A detailed analysis of current artifact removal techniques will then be presented. An evaluation of the advantages and disadvantages of each of the proposed artifact detection and removal techniques, with particular application to the personal healthcare domain, is provided.

  3. Mammographic artifacts on full-field digital mammography.

    Science.gov (United States)

    Choi, Jae Jeong; Kim, Sung Hun; Kang, Bong Joo; Choi, Byung Gil; Song, ByungJoo; Jung, Haijo

    2014-04-01

    This study investigates the incidence of full-field digital mammographic (FFDM) artifacts with three systems at two institutions and compares the artifacts between two detector types and two grid types. A total of 4,440 direct and 4,142 indirect FFDM images were reviewed by two radiologists, and artifacts were classified as patient related, hardware related, and software processing. The overall incidence of FFDM artifacts was 3.4% (292/8,582). Patient related artifacts (motion artifacts and skin line artifacts) were the most commonly detected types (1.7%). Underexposure among hardware related artifacts and high-density artifacts among software processing artifacts also were common (0.7 and 0.5%, respectively). These artifacts, specific to digital mammography, were more common with the direct detector type and the crossed air grid type than with the indirect type and linear grid type (p artifacts on FFDM were patient related, which might be controlled by the instruction of a patient and technologist. Underexposure and high-density artifacts were more common with direct detector and crossed air type of grid.

  4. Artifacts in musculoskeletal ultrasonography.

    Science.gov (United States)

    Taljanovic, Mihra S; Melville, David M; Scalcione, Luke R; Gimber, Lana H; Lorenz, Eileen J; Witte, Russell S

    2014-02-01

    During the past 2 decades, high-resolution ultrasonography (US) has been increasingly utilized in the diagnosis of musculoskeletal trauma and diseases with results comparable with MR imaging. US has an advantage over other cross-sectional modalities in many circumstances due to its superior spatial resolution and ability to allow dynamic assessment. When performing musculoskeletal US, the examiner has to be knowledgeable in the complex anatomy of the musculoskeletal system and US imaging technique. Additionally, he or she must be familiar with several common imaging artifacts in musculoskeletal US that may be mistaken for pathology, as well as several artifacts that frequently accompany pathologic conditions. These artifacts may occur with both B-mode gray-scale and Doppler imaging. In this article, we discuss common artifacts seen in musculoskeletal US and techniques to avoid or minimize these artifacts during clinical US examinations.

  5. Acute bilateral useless hand syndrome: a rare presenting manifestation of vitamin B12 deficiency.

    Science.gov (United States)

    Biyani, Sumant; Jha, Sneh Kumar; Pandey, Suchit; Shukla, Rakesh

    2015-10-16

    We report a case of bilateral useless hand syndrome, a rare presenting manifestation of vitamin B12 deficiency. A 38-year-old man, a strict vegetarian and a teacher by occupation, presented with acute onset clumsiness of both hands while performing fine movements. Detailed history-taking, examination of the patient and relevant investigations (complete blood count, serum vitamin B12 and MRI of the cervical spinal cord) were carried out. Laboratory analysis was suggestive of vitamin B12 deficiency and MRI demonstrated a lesion involving the posterior columns of the cervical cord. The patient was diagnosed as a case of non-compressive cervical myelopathy predominantly involving the posterior column due to vitamin B12 deficiency. Acute bilateral useless hand syndrome can be a rare presenting feature of vitamin B12 deficiency.

  6. Artifacts and essentialism.

    Science.gov (United States)

    Gelman, Susan A

    2013-09-01

    Psychological essentialism is an intuitive folk belief positing that certain categories have a non-obvious inner "essence" that gives rise to observable features. Although this belief most commonly characterizes natural kind categories, I argue that psychological essentialism can also be extended in important ways to artifact concepts. Specifically, concepts of individual artifacts include the non-obvious feature of object history, which is evident when making judgments regarding authenticity and ownership. Classic examples include famous works of art (e.g., the Mona Lisa is authentic because of its provenance), but ordinary artifacts likewise receive value from their history (e.g., a worn and tattered blanket may have special value if it was one's childhood possession). Moreover, in some cases, object history may be thought to have causal effects on individual artifacts, much as an animal essence has causal effects. I review empirical support for these claims and consider the implications for both artifact concepts and essentialism. This perspective suggests that artifact concepts cannot be contained in a theoretical framework that focuses exclusively on similarity or even function. Furthermore, although there are significant differences between essentialism of natural kinds and essentialism of artifact individuals, the commonalities suggest that psychological essentialism may not derive from folk biology but instead may reflect more domain-general perspectives on the world.

  7. PROPELLER (periodically rotated overlapping parallel lines with enhanced reconstruction) and EPI diffusion-weighted MR imaging at 3.0 T: pontine magnetic susceptibility artifacts depend on pneumatization of the sphenoid sinus

    Energy Technology Data Exchange (ETDEWEB)

    Sohn, Chul Ho; Kim, In Soo [College of Medicine, Keimyung University, Daegu (Korea, Republic of)

    2006-10-15

    In the case of well pneumatized sphenoid sinus, magnetic susceptibility artifact can be visualized at the brainstem and especially at the pons on echo-planar imaging (EPI) diffusion-weighted imaging. Fast spin-echo periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) is a novel imaging method that can reduce these artifacts. In 3.0 T MR, we first evaluate the degree of the relationship of pneumatization of the sphenoid sinus with the occurrence of magnetic susceptibility artifacts (MSA) on the echo planar imaging (EPI) diffusion-weighted imaging (DWI), and we evaluated using PROPELLER-DWI for cancellation of MSAs of the pons in the patients who had MSAs on the EPI-DWI. Sixty subjects (mean age: 58 years old and there were 30 men) who were classified according to the two types of sphenoid sinus underwent EPI-DWI. The two types of sphenoid sinus were classified by the degree of pneumatization on the sagittal T2-weighted image. The type-1 sphenoid sinus was 0% to less than 50% aeration of the bony sellar floor, and type-2 was 50% or more aeration of the boney sellar floor. Each of 10 subjects (n = 20/60, mean age: 53) of the two types had PROPELLER and EPI-DWI performed simultaneously. We first evaluated the absence or presence of MSAs at the pons in the two types, and we compared EPI and PROPELLER-DWI in the subjects who underwent the two MR sequences simultaneously. We used 3.0 T MR (Signa VHi, GE, MW, U.S.A.) with a standard head coil. All the MR images were interpreted by one neuroradiologiest. For the type-1, two (6.7%) cases had MSAs and 28 (93.7%) cases did not have MSAs on the EPI-DWI. For the type-2, twenty-seven (90%) cases had MSAs and 3 (10%) cases did not have MSAs on the EPI-DWI. The degree of pneumatization of the sphenoid sinus was related with the occurrence of MSAs of the pons, according to the chi-square test ({rho} = 0.000). All twenty cases who had PROPELLER-DWI performed had no MASs at the pons regardless of

  8. Artifacts in diagnostic ultrasound

    OpenAIRE

    Hindi A; Peterson C; Barr RG

    2013-01-01

    Ammar Hindi,1 Cynthia Peterson,2 Richard G Barr3,41Department of Radiology, University Hospitals of Cleveland, Cleveland, Ohio, USA; 2Department of Allied Health, Kent State University, Salem, OH, USA; 3Department of Radiology, Northeastern Ohio Medical University, Rootstown, OH, USA; 4Radiology Consultants, Youngstown, OH, USAAbstract: Ultrasound artifacts are encountered daily in clinical practice and may be a source of confusion on interpretation. Some artifacts arise secondary to improper...

  9. Facts in artifacts

    Directory of Open Access Journals (Sweden)

    P R Bindhu

    2013-01-01

    Full Text Available Examination of microscopic sections of animal tissues reveals facts which are not always related to its normal histology or pathology. Processing of tissue specimens consists of lengthy procedures from the stage of surgical removal to the stained and mounted microscopic sections. Defects are common in tissue sections as a result of faulty procedures. These defects are referred to as artifacts. They lead to misinterpretation of histopathological diagnosis but at times they throw limelight into diagnosis. This paper attempts to put together all the facts regarding the various artifacts that are encountered in histopathology.

  10. Controlling Modelling Artifacts

    DEFF Research Database (Denmark)

    Smith, Michael James Andrew; Nielson, Flemming; Nielson, Hanne Riis

    2011-01-01

    as the high-level model, so that they can be directly compared. There are two key ideas in our approach — a temporal abstraction, where we only look at the state of the system at certain observable points in time, and a spatial abstraction, where we project onto a smaller state space that summarises...... artifacts that were inadvertently introduced. In this paper, we propose a novel methodology to reason about modelling artifacts, given a detailed model and a highlevel (more abstract) model of the same system. By a series of automated abstraction steps, we lift the detailed model to the same state space...

  11. Search for continuous gravitational waves: improving robustness versus instrumental artifacts

    CERN Document Server

    Keitel, David; Papa, Maria Alessandra; Leaci, Paola; Siddiqi, Maham

    2013-01-01

    The standard multi-detector F-statistic for continuous gravitational waves is susceptible to false alarms from instrumental artifacts, for example monochromatic sinusoidal disturbances (lines). This vulnerability to line artifacts arises because the F-statistic compares the signal hypothesis to a Gaussian-noise hypothesis, and hence is triggered by anything that resembles the signal hypothesis more than Gaussian noise. Various ad-hoc veto methods to deal with such line artifacts have been proposed and used in the past. Here we develop a Bayesian framework that includes an explicit alternative hypothesis to model disturbed data. We introduce a simple line model that defines lines as signal candidates appearing only in one detector. This allows us to explicitly compute the odds between the signal hypothesis and an extended noise hypothesis, resulting in a new detection statistic that is more robust to instrumental artifacts. We present and discuss results from Monte-Carlo tests on both simulated data and on det...

  12. The Information Systems Artifact

    DEFF Research Database (Denmark)

    Chatterjee, Surtirtha; Xiao, Xiao; Elbanna, Amany

    2017-01-01

    Passionate debates regarding the defining characteristic of the “IT artifact” continue. Such debates, and also the lack of explicit consideration of the “information” element in the IT artifact, motivate us to propose a revised conception, drawing upon concepts from General Systems Theory (GST...

  13. The Information Systems Artifact

    DEFF Research Database (Denmark)

    Chatterjee, Surtirtha; Xiao, Xiao; Elbanna, Amany

    2017-01-01

    Passionate debates regarding the defining characteristic of the “IT artifact” continue. Such debates, and also the lack of explicit consideration of the “information” element in the IT artifact, motivate us to propose a revised conception, drawing upon concepts from General Systems Theory (GST...

  14. Controlling Modelling Artifacts

    DEFF Research Database (Denmark)

    Smith, Michael James Andrew; Nielson, Flemming; Nielson, Hanne Riis

    2011-01-01

    the possible configurations of the system (for example, by counting the number of components in a certain state). We motivate our methodology with a case study of the LMAC protocol for wireless sensor networks. In particular, we investigate the accuracy of a recently proposed high-level model of LMAC......When analysing the performance of a complex system, we typically build abstract models that are small enough to analyse, but still capture the relevant details of the system. But it is difficult to know whether the model accurately describes the real system, or if its behaviour is due to modelling...... artifacts that were inadvertently introduced. In this paper, we propose a novel methodology to reason about modelling artifacts, given a detailed model and a highlevel (more abstract) model of the same system. By a series of automated abstraction steps, we lift the detailed model to the same state space...

  15. Small Artifacts - Big Technologies

    DEFF Research Database (Denmark)

    Kreiner, Kristian

    2005-01-01

    The computer IC is the heart of the information and telecommunication technology. It is a tiny artifact, but with incredible organizing powers. We use this physical artifact as the location for studying central problems of the knowledge economy. First, the paper describes the history of chip design...... and the emergence of the technological community involved in designing and manufacturing computer chips. The community is structured in a way that reflects the underlying physical nature silicon and the numerous other materials and chemicals involved. But it also reflects the human agency of defining new projects...... instrument. It is found that technological progress is not hindered, but rather aided by the use of imperfect principles, abstractions and representations of reality. The power of such imperfections is discussed and generalized....

  16. Detection of artifacts from high energy bursts in neonatal EEG.

    Science.gov (United States)

    Bhattacharyya, Sourya; Biswas, Arunava; Mukherjee, Jayanta; Majumdar, Arun Kumar; Majumdar, Bandana; Mukherjee, Suchandra; Singh, Arun Kumar

    2013-11-01

    Detection of non-cerebral activities or artifacts, intermixed within the background EEG, is essential to discard them from subsequent pattern analysis. The problem is much harder in neonatal EEG, where the background EEG contains spikes, waves, and rapid fluctuations in amplitude and frequency. Existing artifact detection methods are mostly limited to detect only a subset of artifacts such as ocular, muscle or power line artifacts. Few methods integrate different modules, each for detection of one specific category of artifact. Furthermore, most of the reference approaches are implemented and tested on adult EEG recordings. Direct application of those methods on neonatal EEG causes performance deterioration, due to greater pattern variation and inherent complexity. A method for detection of a wide range of artifact categories in neonatal EEG is thus required. At the same time, the method should be specific enough to preserve the background EEG information. The current study describes a feature based classification approach to detect both repetitive (generated from ECG, EMG, pulse, respiration, etc.) and transient (generated from eye blinking, eye movement, patient movement, etc.) artifacts. It focuses on artifact detection within high energy burst patterns, instead of detecting artifacts within the complete background EEG with wide pattern variation. The objective is to find true burst patterns, which can later be used to identify the Burst-Suppression (BS) pattern, which is commonly observed during newborn seizure. Such selective artifact detection is proven to be more sensitive to artifacts and specific to bursts, compared to the existing artifact detection approaches applied on the complete background EEG. Several time domain, frequency domain, statistical features, and features generated by wavelet decomposition are analyzed to model the proposed bi-classification between burst and artifact segments. A feature selection method is also applied to select the

  17. Metrological multispherical freeform artifact

    Science.gov (United States)

    Blobel, Gernot; Wiegmann, Axel; Siepmann, Jens; Schulz, Michael

    2016-07-01

    Precisely known artifacts are required to characterize the accuracy of asphere and freeform measuring instruments. To this end the best knowledge of the surface characteristics in conjunction with a low measurement uncertainty are necessary. Because this is a challenging task for typical freeform surfaces used in optical systems, the concept of "metrological" artifacts is introduced. We have developed a multispherical freeform artifact for performance tests of tactile touch probe and contact-free optical measuring systems. The measurement accuracy of the complete form and the deviation from calibrated spherical sections can thus be determined. The radius calibration of multiple spherical sections is performed with an extended radius measuring procedure by interferometry. Evaluated surface forms of different measuring methods and the radii determined can be compared to each other. In this study, a multispherical freeform specimen made of copper, with two differing radii, has been measured by two optical measuring methods, a full field measuring tilted-wave interferometer and a high accuracy cylinder coordinate measuring machine with an optical probe. The surface form measurements are evaluated and compared, and the radii determined are compared to the results of a radius measurement bench.

  18. An Additive Manufacturing Test Artifact

    Science.gov (United States)

    Moylan, Shawn; Slotwinski, John; Cooke, April; Jurrens, Kevin; Donmez, M Alkan

    2014-01-01

    A test artifact, intended for standardization, is proposed for the purpose of evaluating the performance of additive manufacturing (AM) systems. A thorough analysis of previously proposed AM test artifacts as well as experience with machining test artifacts have inspired the design of the proposed test artifact. This new artifact is designed to provide a characterization of the capabilities and limitations of an AM system, as well as to allow system improvement by linking specific errors measured in the test artifact to specific sources in the AM system. The proposed test artifact has been built in multiple materials using multiple AM technologies. The results of several of the builds are discussed, demonstrating how the measurement results can be used to characterize and improve a specific AM system. PMID:26601039

  19. An Additive Manufacturing Test Artifact.

    Science.gov (United States)

    Moylan, Shawn; Slotwinski, John; Cooke, April; Jurrens, Kevin; Donmez, M Alkan

    2014-01-01

    A test artifact, intended for standardization, is proposed for the purpose of evaluating the performance of additive manufacturing (AM) systems. A thorough analysis of previously proposed AM test artifacts as well as experience with machining test artifacts have inspired the design of the proposed test artifact. This new artifact is designed to provide a characterization of the capabilities and limitations of an AM system, as well as to allow system improvement by linking specific errors measured in the test artifact to specific sources in the AM system. The proposed test artifact has been built in multiple materials using multiple AM technologies. The results of several of the builds are discussed, demonstrating how the measurement results can be used to characterize and improve a specific AM system.

  20. The Human-Artifact Model

    DEFF Research Database (Denmark)

    Bødker, Susanne; Klokmose, Clemens Nylandsted

    2011-01-01

    Although devices of all shapes and sizes currently dominate the technological landscape, human–computer interaction (HCI) as a field is not yet theoretically equipped to match this reality. In this article we develop the human–artifact model, which has its roots in activity theoretical HCI....... By reinterpreting the activity theoretical foundation, we present a framework that helps addressing the analysis of individual interactive artifacts while embracing that they are part of a larger ecology of artifacts. We show how the human–artifact model helps structuring the understanding of an artifact's action......-possibilities in relation to the artifact ecology surrounding it. Essential to the model is that it provides four interconnected levels of analysis and addresses the possibilities and problems at these four levels. Artifacts and their use are constantly developing, and we address development in, and of, use. The framework...

  1. New Blocking Artifacts Reduction Method Based on Wavelet Transform

    Institute of Scientific and Technical Information of China (English)

    SHI Min; YI Qing-ming

    2007-01-01

    It is well known that a block discrete cosine transform compressed image exhibits visually annoying blocking artifacts at low-bit-rate. A new post-processing deblocking algorithm in wavelet domain is proposed. The algorithm exploits blocking-artifact features shown in wavelet domain. The energy of blocking artifacts is concentrated into some lines to form annoying visual effects after wavelet transform. The aim of reducing blocking artifacts is to capture excessive energy on the block boundary effectively and reduce it below the visual scope. Adaptive operators for different subbands are computed based on the wavelet coefficients. The operators are made adaptive to different images and characteristics of blocking artifacts. Experimental results show that the proposed method can significantly improve the visual quality and also increase the peak signal-noise-ratio(PSNR) in the output image.

  2. Search for continuous gravitational waves: Improving robustness versus instrumental artifacts

    Science.gov (United States)

    Keitel, David; Prix, Reinhard; Papa, Maria Alessandra; Leaci, Paola; Siddiqi, Maham

    2014-03-01

    The standard multidetector F-statistic for continuous gravitational waves is susceptible to false alarms from instrumental artifacts, for example monochromatic sinusoidal disturbances ("lines"). This vulnerability to line artifacts arises because the F-statistic compares the signal hypothesis to a Gaussian-noise hypothesis, and hence is triggered by anything that resembles the signal hypothesis more than Gaussian noise. Various ad-hoc veto methods to deal with such line artifacts have been proposed and used in the past. Here we develop a Bayesian framework that includes an explicit alternative hypothesis to model disturbed data. We introduce a simple line model that defines lines as signal candidates appearing only in one detector. This allows us to explicitly compute the odds between the signal hypothesis and an extended noise hypothesis, resulting in a new detection statistic that is more robust to instrumental artifacts. We present and discuss results from Monte-Carlo tests on both simulated data and on detector data from the fifth LIGO science run. We find that the line-robust statistic retains the detection power of the standard F-statistic in Gaussian noise. In the presence of line artifacts it is more sensitive, even compared to the popular F-statistic consistency veto, over which it improves by as much as a factor of two in detectable signal strength.

  3. A particle accelerator probes artifacts

    CERN Document Server

    Dran, J C; Salomon, J

    2002-01-01

    The AGLAE system is made up of a 2 mega volts electrostatic accelerator and of 3 irradiation lines: one leads to a vacuum enclosure in which targets are irradiated and the 2 others lines are designed to irradiate targets under an air or helium atmosphere. The AGLAE system is located in the premises of the Louvre museum in Paris and is devoted to the study of cultural objects through ion beam analysis (IBA). 4 techniques are used: -) proton-induced X-ray emission (PIXE) -) proton-induced gamma ray (PIGE) -) Rutherford backscattering spectrometry (NRS) and -) nuclear reaction analysis (NRA). A decisive progress has permitted the direct analysis of artifacts without sampling. The object itself is set just a few millimeters away from the exit window of the beam in an air or helium atmosphere. The exit window must be resistant enough to bear the atmospheric pressure and the damages caused by the proton beam but must be thin enough to not deteriorate the quality of the beam. By using a 10 sup - sup 7 m thick exit w...

  4. From Ecological Sounding Artifacts Towards Sonic Artifact Ecologies

    DEFF Research Database (Denmark)

    Erkut, Cumhur; Serafin, Stefania

    2016-01-01

    The discipline of sonic interaction design has been focused on the interaction between a single user and an artifact. This strongly limits one of the fundamental aspects of music as a social and interactive experience. In this paper we propose sonic artifact ecologies as a mean to examine...

  5. Spherical artifacts on ferrograms

    Science.gov (United States)

    Jones, W. R., Jr.

    1976-01-01

    In the past, hollow spheres detected on ferrograms have been interpreted as being due to fretting, abrasion, cavitation erosion, and fatigue-related processes. Here it is reported that such spheres were found to result from the fact that a routine grinding operation on a steel plate was carried out about 20 feet away from the ferrograph. A similar grinding operation was performed on a piece of low carbon steel a few feet from the ferrograph, and after a few minutes of grinding, the resulting ferrogram contained thousands of particles of which more than 90% were spherical. Because of the widespread occurrence of ordinary grinding operations, it seems prudent that those utilizing the ferrograph be cognizant of this type of artifact.

  6. Artifacts in digital images

    Science.gov (United States)

    Lorre, J. J.; Gillespie, A. R.

    1980-01-01

    Three kinds of artifacts unique to digital images are illustrated, namely aliasing caused by undersampling, interference phenomena caused by improper display of images, and harmonic overtones caused by quantization of amplitudes. Special attention is given to undersampling when the sample size and interval are the same. It is noted that this situation is important because it is typical of solid-state cameras. Quantization of image data of necessity introduces energy at harmonic overtones of the image spectrum. This energy is aliased if the frequency of the overtones is greater than 0.5 cycle/pixel. It cannot be selectively removed from the image through filtering, and the best way to suppress it is to maximize the amplification of the sensor before digital encoding.

  7. Archaeology, Artifacts, and Cosmochemistry

    Science.gov (United States)

    Martel, L. M. V.

    2017-06-01

    PSRD covers research that ascertains the content, formation, and evolution of our Solar System and planetary systems in general. Our archives are full of sample-based studies of extraterrestrial materials that relate to the building of planets, moons, and minor bodies. Rarely do we cover the cosmochemistry of artifacts, but the importance of cosmochemistry is abundantly clear in this story of artisan iron beads of archaeological significance and the quest to find the source meteorite. Twenty-two meteoritic iron beads, recovered from mounds in Havana, Illinois of the Hopewell people and culture, have been identified as pieces of the Anoka iron meteorite, according to work by Timothy McCoy (National Museum of Natural History, Smithsonian Institution), Amy Marquardt (undergraduate intern at the NMNH/SI and now at the University of Colorado at Boulder), John Wasson (UCLA), Richard Ash (University of Maryland), and Edward Vicenzi (SI).

  8. Sound as artifact

    Science.gov (United States)

    Benjamin, Jeffrey L.

    A distinguishing feature of the discipline of archaeology is its reliance upon sensory dependant investigation. As perceived by all of the senses, the felt environment is a unique area of archaeological knowledge. It is generally accepted that the emergence of industrial processes in the recent past has been accompanied by unprecedented sonic extremes. The work of environmental historians has provided ample evidence that the introduction of much of this unwanted sound, or "noise" was an area of contestation. More recent research in the history of sound has called for more nuanced distinctions than the noisy/quiet dichotomy. Acoustic archaeology tends to focus upon a reconstruction of sound producing instruments and spaces with a primary goal of ascertaining intentionality. Most archaeoacoustic research is focused on learning more about the sonic world of people within prehistoric timeframes while some research has been done on historic sites. In this thesis, by way of a meditation on industrial sound and the physical remains of the Quincy Mining Company blacksmith shop (Hancock, MI) in particular, I argue for an acceptance and inclusion of sound as artifact in and of itself. I am introducing the concept of an individual sound-form, or sonifact , as a reproducible, repeatable, representable physical entity, created by tangible, perhaps even visible, host-artifacts. A sonifact is a sound that endures through time, with negligible variability. Through the piecing together of historical and archaeological evidence, in this thesis I present a plausible sonifactual assemblage at the blacksmith shop in April 1916 as it may have been experienced by an individual traversing the vicinity on foot: an 'historic soundwalk.' The sensory apprehension of abandoned industrial sites is multi-faceted. In this thesis I hope to make the case for an acceptance of sound as a primary heritage value when thinking about the industrial past, and also for an increased awareness and acceptance

  9. Artifacts in musculoskeletal MR imaging.

    Science.gov (United States)

    Singh, Dinesh R; Chin, Michael S M; Peh, Wilfred C G

    2014-02-01

    MR imaging has become an important diagnostic tool in the evaluation of a vast number of pathologies and is of foremost importance in the evaluation of spine, joints, and soft tissue structures of the musculoskeletal system. MR imaging is susceptible to various artifacts that may affect the image quality or even simulate pathologies. Some of these artifacts have gained special importance with the use of higher field strength magnets and with the increasing need for MR imaging in postoperative patients, especially those with previous joint replacements or metallic implants. Artifacts may arise from patient motion or could be due to periodic motion, such as vascular and cardiac pulsation. Artifacts could also arise from various protocol errors including saturation, wraparound, truncation, shading, partial volume averaging, and radiofrequency interference artifacts. Susceptibility artifact occurs at interfaces with different magnetic susceptibilities and is of special importance with increasing use of metallic joint replacement prostheses. Magic angle phenomenon is a special type of artifact that occurs in musculoskeletal MR imaging. It is essential to recognize these artifacts and to correct them because they may produce pitfalls in image interpretation.

  10. Teaching World Cultures through Artifacts

    Science.gov (United States)

    Hauf, James E.

    2010-01-01

    Teaching world cultures in the middle-level geography classroom presents challenges both because of the complexity of culture and because of the characteristics of students of this age. One effective way to teach about a culture is through the use of cultural artifacts. This article discusses how to collect and use cultural artifacts in the…

  11. Intention, History, and Artifact Concepts.

    Science.gov (United States)

    Bloom, Paul

    1996-01-01

    Claims that people determine whether something is a member of a given artifact kind by inferring that it was successfully created with the intention that it belong to that kind. Discusses function-based and intentional-historical accounts of artifact concepts. Concludes that a rich set of inferential capacities is needed to constitute a theory of…

  12. Turquoise Artifact from Teotihuacan

    Energy Technology Data Exchange (ETDEWEB)

    Spence, Michael W.; Harbottle, Garman; Weigand, Phil C.

    1999-07-01

    Turquoise artifacts appeared sporadically in Mesoamerica as early as the Formative period (Merry de Morales 1987:100, Figure 8.4; Weigand 1989:43). Most occurrences, however, postdate the collapse of Teotihuacan. In the Late Classic and Postclassic periods increasing quantities are found, often in the form of elaborate mosaics, in a wide variety of contexts in central, west and northwest Mexico. Neutron activation analysis has determined that much of this turquoise derives from sources in the southwestern United States (Weigand et al. 1977; Harbottle and Weigand 1992; Weigand and Harbottle 1993). Teotihuacan played a major role in Mesoamerica during the Terminal Formative and Early-Middle Classic periods. It was the dominant power in central Mexico from about the time of Christ to its collapse at about A.D. 650 (Millon 1988, 1992; Cowgill 1996). Throughout this period goods flowed into Teotihuacan from many parts of the Mesoamerican world. Despite this widespread economic interaction, only two pieces of turquoise have been recovered in the city. In the following pages, the context and implications of one of these finds will be examined.

  13. Investigating media artifacts with children

    DEFF Research Database (Denmark)

    Chimirri, Niklas Alexander

    The dissertation’s aim is to explore the everyday relevance media artifacts have for young children. It discusses and further develops analytical concepts that are committed to taking the children’s perspectives on possibilities and limitations of such artifacts seriously. These conceptual...... developments are rooted in the author’s participation in a daycare practice in Berlin, Germany. The daycare’s situational approach precisely attempted to draw on the children’s everyday life experiences so as to engage in problem-oriented learning projects, on media artifacts and beyond....

  14. Sampling Artifacts from Conductive Silicone Tubing

    Energy Technology Data Exchange (ETDEWEB)

    Timko, Michael T.; Yu, Zhenhong; Kroll, Jesse; Jayne, John T.; Worsnop, Douglas R.; Miake-Lye, Richard C.; Onasch, Timothy B.; Liscinsky, David; Kirchstetter, Thomas W.; Destaillats, Hugo; Holder, Amara L.; Smith, Jared D.; Wilson, Kevin R.

    2009-05-15

    We report evidence that carbon impregnated conductive silicone tubing used in aerosol sampling systems can introduce two types of experimental artifacts: 1) silicon tubing dynamically absorbs carbon dioxide gas, requiring greater than 5 minutes to reach equilibrium and 2) silicone tubing emits organic contaminants containing siloxane that adsorb onto particles traveling through it and onto downstream quartz fiber filters. The consequence can be substantial for engine exhaust measurements as both artifacts directly impact calculations of particulate mass-based emission indices. The emission of contaminants from the silicone tubing can result in overestimation of organic particle mass concentrations based on real-time aerosol mass spectrometry and the off-line thermal analysis of quartz filters. The adsorption of siloxane contaminants can affect the surface properties of aerosol particles; we observed a marked reduction in the water-affinity of soot particles passed through conductive silicone tubing. These combined observations suggest that the silicone tubing artifacts may have wide consequence for the aerosol community and should, therefore, be used with caution. Gentle heating, physical and chemical properties of the particle carriers, exposure to solvents, and tubing age may influence siloxane uptake. The amount of contamination is expected to increase as the tubing surface area increases and as the particle surface area increases. The effect is observed at ambient temperature and enhanced by mild heating (<100 oC). Further evaluation is warranted.

  15. Cytological artifacts masquerading interpretation

    Science.gov (United States)

    Sahay, Khushboo; Mehendiratta, Monica; Rehani, Shweta; Kumra, Madhumani; Sharma, Rashi; Kardam, Priyanka

    2013-01-01

    Background: Cytological artifacts are important to learn because an error in routine laboratory practice can bring out an erroneous result. Aims: The aim of this study was to analyze the effects of delayed fixation and morphological discrepancies created by deliberate addition of extraneous factors on the interpretation and/or diagnosis of an oral cytosmear. Materials and Methods: A prospective study was carried out using papanicolaou and hematoxylin and eosin-stained oral smears, 6 each from 66 volunteer dental students with deliberate variation in fixation delay timings, with and without changes in temperature, undue pressure while smear making and intentional addition of contaminants. The fixation delay at room temperature was carried out at an interval of every 30 minutes, 1 day and 1 week and was continued till the end of 1 day, 1 week, and 1 month, respectively. The temperature variations included 60 to 70°C and 3 to 4°C. Results: Light microscopically, the effect of delayed fixation at room temperature appeared first on cytoplasm followed by nucleus within the first 2 hours and on the 4th day, respectively, till complete cytoplasmic degeneration on the 23rd day. However, delayed fixation at variable temperature brought faster degenerative changes at higher temperature than lower temperature. Effect of extraneous factors revealed some interesting facts. Conclusions: In order to justify a cytosmear interpretation, a cytologist must be well acquainted with delayed fixation-induced cellular changes and microscopic appearances of common contaminants so as to implicate better prognosis and therapy. PMID:24648667

  16. Reclaiming space for learning in liturgical contexts: Cracks in the maxim of the uselessness of liturgical ritual

    Directory of Open Access Journals (Sweden)

    Marcel Barnard

    2012-02-01

    Full Text Available The problem addressed in this article is, that empirical and theoretical research appears to demonstrate that liturgy often aims at certain results. This, however, puts the widely accepted notion in Liturgical Studies of the so-called uselessness of liturgical ritual under pressure. Against this background in Liturgical Studies the aim of this article is to reclaim space in academic discourses on liturgy for learning in liturgical contexts. The latter is done by presenting several liturgical models, revisiting arguments regarding the (non functionality of ritual or religion and also by reflecting on ritual-liturgical data that the authors personally collected as part of two research projects.

  17. Evaluation of Audio Compression Artifacts

    Directory of Open Access Journals (Sweden)

    M. Herrera Martinez

    2007-01-01

    Full Text Available This paper deals with subjective evaluation of audio-coding systems. From this evaluation, it is found that, depending on the type of signal and the algorithm of the audio-coding system, different types of audible errors arise. These errors are called coding artifacts. Although three kinds of artifacts are perceivable in the auditory domain, the author proposes that in the coding domain there is only one common cause for the appearance of the artifact, inefficient tracking of transient-stochastic signals. For this purpose, state-of-the art audio coding systems use a wide range of signal processing techniques, including application of the wavelet transform, which is described here. 

  18. Potential uselessness and futility of left atrial appendage occlusion and patent foramen ovale closure in cardioembolic stroke.

    Science.gov (United States)

    Nicolosi, Gian L

    2017-02-16

    International guidelines indicate that interventional closure of left atrial appendage and patent foramen ovale may be considered in selected patients for stroke prevention. These procedures appear, however, from the published literature, at high risk of uselessness and futility in the single case, if not even capable to induce harm and adverse events. In fact, all reported systematic reviews and meta-analyses have not shown in a convincing manner the superiority of these procedures in stroke prevention, taking into account the occurrence of possible complications also, as compared with alternative medical treatment. On the basis of these considerations, it becomes very difficult to define always and unequivocally how adequate and complete was the information when given to each single candidate patient before the procedure by the Heart Team, the left atrial appendage occlusion Team or patent foramen ovale closure Team, potentially involved in conflict of interest. Before indicating these procedures, a complete diagnostic work-up should then be planned for each single patient to identify and treat not only one, but all concomitant risk factors and potential different cardioembolic sources. It could also be suggested to have, for each single candidate patient, a second independent opinion from physicians not involved in the procedure and possibly not operating in the same institution. This prudential approach could reduce in each single case the risk of uselessness, futility and even potential harm and adverse events of those procedures.

  19. Text Signals Influence Team Artifacts

    Science.gov (United States)

    Clariana, Roy B.; Rysavy, Monica D.; Taricani, Ellen

    2015-01-01

    This exploratory quasi-experimental investigation describes the influence of text signals on team visual map artifacts. In two course sections, four-member teams were given one of two print-based text passage versions on the course-related topic "Social influence in groups" downloaded from Wikipedia; this text had two paragraphs, each…

  20. Toddlers View Artifact Function Normatively

    Science.gov (United States)

    Casler, Krista; Terziyan, Treysi; Greene, Kimberly

    2009-01-01

    When children use objects like adults, are they simply tracking regularities in others' object use, or are they demonstrating a normatively defined awareness that there are right and wrong ways to act? This study provides the first evidence for the latter possibility. Young 2- and 3-year-olds (n = 32) learned functions of 6 artifacts, both…

  1. Technical artifacts: An integrated perspective

    NARCIS (Netherlands)

    Borgo, S.; Franssen, M.P.M.; Garbacz, P.; Kitamura, Y.; Mizoguchi, R.; Vermaas, P.E.

    2014-01-01

    Humans are always interested in distinguishing natural and artificial entities although there is no sharp demarcation between the two categories. Surprisingly, things do not improve when the second type of entities is restricted to the arguably more constrained realm of physical technical artifacts.

  2. Modeling Software Processes and Artifacts

    NARCIS (Netherlands)

    van den Berg, Klaas; Bosch, Jan; Mitchell, Stuart

    1997-01-01

    The workshop on Modeling Software Processes and Artifacts explored the application of object technology in process modeling. After the introduction and the invited lecture, a number of participants presented their position papers. First, an overview is given on some background work, and the aims, as

  3. Withanolide artifacts formed in methanol.

    Science.gov (United States)

    Cao, Cong-Mei; Zhang, Huaping; Gallagher, Robert J; Timmermann, Barbara N

    2013-11-22

    Methanol solutions of the main withanolides (6-8) naturally present in Physalis longifolia yielded five artificial withanolides (1-5), including three new compounds (1-3). Withanolides 1 and 2 were identified as intramolecular Michael addition derivatives, while withanolides 3-5 were the result of intermolecular Michael addition. A comprehensive literature investigation was conducted to identify potential withanolide Michael addition artifacts isolated from Solanaceous species to date.

  4. [Quantitative Evaluation of Metal Artifacts on CT Images on the Basis of Statistics of Extremes].

    Science.gov (United States)

    Kitaguchi, Shigetoshi; Imai, Kuniharu; Ueda, Suguru; Hashimoto, Naomi; Hattori, Shouta; Saika, Takahiro; Ono, Yoshifumi

    2016-05-01

    It is well-known that metal artifacts have a harmful effect on the image quality of computed tomography (CT) images. However, the physical property remains still unknown. In this study, we investigated the relationship between metal artifacts and tube currents using statistics of extremes. A commercially available phantom for measuring CT dose index 160 mm in diameter was prepared and a brass rod 13 mm in diameter was placed at the centerline of the phantom. This phantom was used as a target object to evaluate metal artifacts and was scanned using an area detector CT scanner with various tube currents under a constant tube voltage of 120 kV. Sixty parallel line segments with a length of 100 pixels were placed to cross metal artifacts on CT images and the largest difference between two adjacent CT values in each of 60 CT value profiles of these line segments was employed as a feature variable for measuring metal artifacts; these feature variables were analyzed on the basis of extreme value theory. The CT value variation induced by metal artifacts was statistically characterized by Gumbel distribution, which was one of the extreme value distributions; namely, metal artifacts have the same statistical characteristic as streak artifacts. Therefore, Gumbel evaluation method makes it possible to analyze not only streak artifacts but also metal artifacts. Furthermore, the location parameter in Gumbel distribution was shown to be in inverse proportion to the square root of a tube current. This result suggested that metal artifacts have the same dose dependence as image noises.

  5. Automatic Artifact Removal from Electroencephalogram Data Based on A Priori Artifact Information

    Directory of Open Access Journals (Sweden)

    Chi Zhang

    2015-01-01

    Full Text Available Electroencephalogram (EEG is susceptible to various nonneural physiological artifacts. Automatic artifact removal from EEG data remains a key challenge for extracting relevant information from brain activities. To adapt to variable subjects and EEG acquisition environments, this paper presents an automatic online artifact removal method based on a priori artifact information. The combination of discrete wavelet transform and independent component analysis (ICA, wavelet-ICA, was utilized to separate artifact components. The artifact components were then automatically identified using a priori artifact information, which was acquired in advance. Subsequently, signal reconstruction without artifact components was performed to obtain artifact-free signals. The results showed that, using this automatic online artifact removal method, there were statistical significant improvements of the classification accuracies in both two experiments, namely, motor imagery and emotion recognition.

  6. Artifacts in three-dimensional transesophageal echocardiography.

    Science.gov (United States)

    Faletra, Francesco Fulvio; Ramamurthi, Alamelu; Dequarti, Maria Cristina; Leo, Laura Anna; Moccetti, Tiziano; Pandian, Natesa

    2014-05-01

    Three-dimensional (3D) transesophageal echocardiography (TEE) is subject to the same types of artifacts encountered on two-dimensional TEE. However, when displayed in a 3D format, some of the artifacts appear more "realistic," whereas others are unique to image acquisition and postprocessing. Three-dimensional TEE is increasingly used in the setting of percutaneous catheter-based interventions and ablation procedures, and 3D artifacts caused by the metallic components of catheters and devices are particularly frequent. Knowledge of these artifacts is of paramount relevance to avoid misinterpretation of 3D images. Although artifacts and pitfalls on two-dimensional echocardiography are well described and classified, a systematic description of artifacts in 3D transesophageal echocardiographic images and how they affect 3D imaging is still absent. The aim of this review is to describe the most relevant artifacts on 3D TEE, with particular emphasis on those occurring during percutaneous interventions for structural heart disease and ablation procedures.

  7. LINES

    Directory of Open Access Journals (Sweden)

    Minas Bakalchev

    2015-10-01

    Full Text Available The perception of elements in a system often creates their interdependence, interconditionality, and suppression. The lines from a basic geometrical element have become the model of a reductive world based on isolation according to certain criteria such as function, structure, and social organization. Their traces are experienced in the contemporary world as fragments or ruins of a system of domination of an assumed hierarchical unity. How can one release oneself from such dependence or determinism? How can the lines become less “systematic” and forms more autonomous, and less reductive? How is a form released from modernistic determinism on the new controversial ground? How can these elements or forms of representation become forms of action in the present complex world? In this paper, the meaning of lines through the ideas of Le Corbusier, Leonidov, Picasso, and Hitchcock is presented. Spatial research was made through a series of examples arising from the projects of the architectural studio “Residential Transformations”, which was a backbone for mapping the possibilities ranging from playfulness to exactness, as tactics of transformation in the different contexts of the contemporary world.

  8. First aid training in driving schools - uselessness or relevant measure with considerable potential?

    Directory of Open Access Journals (Sweden)

    Petr Zámečník

    2014-12-01

    Full Text Available Despite various traffic safety measures traffic accidents still happen. In the Czech Republic, 57 serious accidents happen every day. In situation of accident, immediate help of the bystanders can save lives and reduce damage. Providers of the first aid can also significantly shorten the time before the professional medical assistance arrives by performing the correct procedure of calling emergency line. Czech Red Cross estimates that approximately 10% of the traffic accidents victims should be saved if the bystanders were more able or willing to give them a first aid. In the Czech Republic the system of dispatcher-assisted resuscitation is very well elaborated. After calling the emergency numbers operators are ready to provide the help and advice. Therefore there are no high requirements to the medical knowledge of the first aid providers. That is why the mandatory first aid courses in driving school are only four hours long, what is from expert point of view very unsufficient. Therefore aim of this research was to carry out screening study of effectiveness of the first aid courses in driving schools. In frame of this study was done questionnaire survey among trainees in driving schools focused on willingness and ability to provide first aid and subjective evaluation of these competences. We used adapted Adelborg's first aid questionnaire (Sp?rgeskema om f?rdselsrelateret f?rstehj?lp og genoplivning. The questionnaire was consisted of four parts. The first part affects the socio-demographic data, the second part affects the subjective evaluation of their own competencies, the third part focuses on the evaluation of the course itself and the fourth part takes the form of a test of actual knowledge of first aid. In the fourth part were respondents asked four most important questions in line with the European Resuscitation Council Guidelines for Resuscitation and with International first aid and resuscitation guidelines of International Federation

  9. Automatic probe artifact detection in MRI-guided cryoablation

    Science.gov (United States)

    Liu, Xinyang; Tuncali, Kemal; Wells, William M.; Zientara, Gary P.

    2013-03-01

    Probe or needle artifact detection in 3D scans gives an approximate location for the tools inserted, and is thus crucial in assisting many image-guided procedures. Conventional needle localization algorithms often start with cropped images, where unwanted parts of raw scans are cropped either manually or by applying pre-defined masks. In cryoablation, however, the number of probes used, the placement and direction of probe insertion, and the portions of abdomen scanned differs significantly from case to case, and probes are often constantly being adjusted during the Probe Placement Phase. These features greatly reduce the practicality of approaches based on image cropping. In this work, we present a fully Automatic Probe Artifact Detection method, APAD, that works directly on uncropped raw MRI images, taken during the Probe Placement Phase in 3Tesla MRI-guided cryoablation. The key idea of our method is to first locate an initial 2D line strip within a slice of the MR image which approximates the position and direction of the 3D probes bundle, noting that cryoprobes or biopsy needles create a signal void (black) artifact in MRI with a bright cylindrical border. With the initial 2D line, standard approaches to detect line structures such as the 3D Hough Transform can be applied to quickly detect each probe's axis. By comparing with manually labeled probes, the analysis of 5 patient treatment cases of kidney cryoablation with varying probe placements demonstrates that our algorithm combined with standard 3D line detection is an accurate and robust method to detect probe artifacts.

  10. Evaluation of artifact reduction in optical coherence tomography angiography with real-time tracking and motion correction technology.

    Science.gov (United States)

    Camino, Acner; Zhang, Miao; Gao, Simon S; Hwang, Thomas S; Sharma, Utkarsh; Wilson, David J; Huang, David; Jia, Yali

    2016-10-01

    Artifacts introduced by eye motion in optical coherence tomography angiography (OCTA) affect the interpretation of images and the quantification of parameters with clinical value. Eradication of such artifacts in OCTA remains a technical challenge. We developed an algorithm that recognizes five different types of motion artifacts and used it to evaluate the performance of three motion removal technologies. On en face maximum projection of flow images, the summed flow signal in each row and column and the correlation between neighboring rows and columns were calculated. Bright line artifacts were recognized by large summed flow signal. Drifts, distorted lines, and stretch artifacts exhibited abnormal correlation values. Residual lines were simultaneously a local maximum of summed flow and a local minimum of correlation. Tracking-assisted scanning integrated with motion correction technology (MCT) demonstrated higher performance than tracking or MCT alone in healthy and diabetic eyes.

  11. MADR: metal artifact detection and reduction

    Science.gov (United States)

    Jaiswal, Sunil Prasad; Ha, Sungsoo; Mueller, Klaus

    2016-04-01

    Metal in CT-imaged objects drastically reduces the quality of these images due to the severe artifacts it can cause. Most metal artifacts reduction (MAR) algorithms consider the metal-affected sinogram portions as the corrupted data and replace them via sophisticated interpolation methods. While these schemes are successful in removing the metal artifacts, they fail to recover some of the edge information. To address these problems, the frequency shift metal artifact reduction algorithm (FSMAR) was recently proposed. It exploits the information hidden in the uncorrected image and combines the high frequency (edge) components of the uncorrected image with the low frequency components of the corrected image. Although this can effectively transfer the edge information of the uncorrected image, it also introduces some unwanted artifacts. The essential problem of these algorithms is that they lack the capability of detecting the artifacts and as a result cannot discriminate between desired and undesired edges. We propose a scheme that does better in these respects. Our Metal Artifact Detection and Reduction (MADR) scheme constructs a weight map which stores whether a pixel in the uncorrected image belongs to an artifact region or a non-artifact region. This weight matrix is optimal in the Linear Minimum Mean Square Sense (LMMSE). Our results demonstrate that MADR outperforms the existing algorithms and ensures that the anatomical structures close to metal implants are better preserved.

  12. Encryption is Useless!?

    CERN Multimedia

    IT Department

    2011-01-01

    This week FTP (the file transfer protocol) celebrated its 40th birthday - and will hopefully retire soon! While a nice and simple means of transferring files, it is totally insecure: both the transferred contents and the authentication password are transfered unencrypted. FTP is not the only protocol that transfers data unencrypted: standard web traffic (“HTTP”) and e-mail (“SMTP”) are not encrypted either. Not an issue? Think again! Nowadays, we all use wireless Ethernet from our laptops and mobile phones. This means that your traffic can be intercepted by anyone*… What if I could your web browsing history, read your last e-mail to your boyfriend/girlfriend, or see which commands you’ve just executed? I could easily intercept your Facebook session… If this worries you, check for secrecy and encryption. Usually this is shown by an “S” in your communication protocol:   · “HTTPS&...

  13. 'Plans are useless'.

    Science.gov (United States)

    Bland, Michael

    2013-01-01

    An essential element in crisis recovery is the protection and/or recovery of reputation. This calls for a crisis communications function that is of more than passing interest to the business continuity specialist and which presents two major challenges in this era of process-driven management: (1) it is an inexact science, more about common sense, psychology, empathy and 'playing it by ear' than about box ticking; (2) it does not lend itself to detailed, rigid plans, although some degree of planning is essential. This paper outlines a flexible approach that will help the crisis team to develop a workable communications plan that strikes a balance between being too detailed and too sketchy. It argues that the whole management team should be involved in developing the plan and sets a number of questions, which, on being answered, will help a realistic, achievable and effective plan to evolve.

  14. Evaluating an artifact in design science research

    CSIR Research Space (South Africa)

    Herselman, M

    2015-09-01

    Full Text Available as the artifact which was evaluated. This example from practice can contribute towards an enhanced understanding of the evaluation of DSR artifacts and the contribution of program theory during both the ex ante and ex post part of the development....

  15. Conceptual Model of Artifacts for Design Science Research

    DEFF Research Database (Denmark)

    Bækgaard, Lars

    2015-01-01

    We present a conceptual model of design science research artifacts. The model views an artifact at three levels. At the artifact level a selected artifact is viewed as a combination of material and immaterial aspects and a set of representations hereof. At the design level the selected artifact...

  16. Dental material artifacts on MR images.

    Science.gov (United States)

    Hinshaw, D B; Holshouser, B A; Engstrom, H I; Tjan, A H; Christiansen, E L; Catelli, W F

    1988-03-01

    Magnetic resonance (MR) imaging of the head and neck is becoming an important aid in evaluating pathologic conditions of the brain, midface, and pharynx. Certain dental materials cause artifacts during MR imaging of the lower midface. These artifacts can obscure the normal anatomy. This study describes the degree of artifact production caused by various materials commonly used in dental restorations. Of the materials tested, those causing artifacts were made of stainless steel, such as orthodontic bands used for braces, and pins or posts that are commonly drilled into teeth to provide structure or stability before filling. Materials used as temporary or permanent fillings or crowns--such as amalgam, gold alloy, aluminum, microfilled resin, and polyvinyl acrylics--did not cause artifacts in the images.

  17. The Many Faces of Computational Artifacts

    DEFF Research Database (Denmark)

    Christensen, Lars Rune; Harper, Richard

    2016-01-01

    Building on data from fieldwork at a medical department, this paper focuses on the varied nature of computational artifacts in practice. It shows that medical practice relies on multiple heterogeneous computational artifacts that form complex constellations. In the hospital studied...... the computational artifacts are both coordinative, image-generating, and intended for the control of nuclear-physical and chemical processes. Furthermore, the paper entails a critique of the notion of ‘computer support’, for not capturing the diverse constitutive powers of computer technology; its types if you will....... The paper is a step towards establishing a lexicon of computational artifacts in practice. It is a call for a wider effort to systematically conceptualise the multiple and specifiable ways in which computational artifacts may be part of work activities. This is for the benefit of design and our...

  18. A method for quantitative assessment of artifacts in EEG, and an empirical study of artifacts.

    Science.gov (United States)

    Kappel, Simon L; Looney, David; Mandic, Danilo P; Kidmose, Preben

    2014-01-01

    Wearable EEG systems for continuous brain monitoring is an emergent technology that involves significant technical challenges. Some of these are related to the fact that these systems operate in conditions that are far less controllable with respect to interference and artifacts than is the case for conventional systems. Quantitative assessment of artifacts provides a mean for optimization with respect to electrode technology, electrode location, electronic instrumentation and system design. To this end, we propose an artifact assessment method and evaluate it over an empirical study of 3 subjects and 5 different types of artifacts. The study showed consistent results across subjects and artifacts.

  19. Silicon bulk micromachined hybrid dimensional artifact.

    Energy Technology Data Exchange (ETDEWEB)

    Claudet, Andre A.; Tran, Hy D.; Bauer, Todd Marks; Shilling, Katherine Meghan; Oliver, Andrew David

    2010-03-01

    A mesoscale dimensional artifact based on silicon bulk micromachining fabrication has been developed and manufactured with the intention of evaluating the artifact both on a high precision coordinate measuring machine (CMM) and video-probe based measuring systems. This hybrid artifact has features that can be located by both a touch probe and a video probe system with a k=2 uncertainty of 0.4 {micro}m, more than twice as good as a glass reference artifact. We also present evidence that this uncertainty could be lowered to as little as 50 nm (k=2). While video-probe based systems are commonly used to inspect mesoscale mechanical components, a video-probe system's certified accuracy is generally much worse than its repeatability. To solve this problem, an artifact has been developed which can be calibrated using a commercially available high-accuracy tactile system and then be used to calibrate typical production vision-based measurement systems. This allows for error mapping to a higher degree of accuracy than is possible with a glass reference artifact. Details of the designed features and manufacturing process of the hybrid dimensional artifact are given and a comparison of the designed features to the measured features of the manufactured artifact is presented and discussed. Measurement results from vision and touch probe systems are compared and evaluated to determine the capability of the manufactured artifact to serve as a calibration tool for video-probe systems. An uncertainty analysis for calibration of the artifact using a CMM is presented.

  20. Visual quality beyond artifact visibility

    Science.gov (United States)

    Redi, Judith A.

    2013-03-01

    The Electronic imaging community has devoted a lot of effort to the development of technologies that can predict the visual quality of images and videos, as a basis for the delivery of optimal visual quality to the user. These systems have been based for the most part on a visibility-centric approach, assuming the more artifacts are visible, the higher is the annoyance they provoke, the lower the visual quality. Despite the remarkable results achieved with this approach, recently a number of studies suggested that the visibility-centric approach to visual quality might have limitations, and that other factors might influence the overall quality impression of an image or video, depending on cognitive and affective mechanisms that work on top of perception. In particular, interest in the visual content, engagement and context of usage have been found to impact on the overall quality impression of the image/video. In this paper, we review these studies and explore the impact that affective and cognitive processes have on the visual quality. In addition, as a case study, we present the results of an experiment investigating on the impact of aesthetic appeal on visual quality, and we show that users tend to be more demanding in terms of visual quality judging beautiful images.

  1. Genetic Analysis on Useless Pod Rate of Summer Soybean%夏大豆瘪荚率的遗传分析

    Institute of Scientific and Technical Information of China (English)

    郭建秋; 张向召; 马雯; 雷全奎; 杨小兰; 李月霞

    2012-01-01

    大豆荚而不实在黄淮区大豆生产中频繁发生,为探讨不同大豆品种荚而不实的遗传差异,以瘪荚率为指标,对豫豆25号×中黄24、冀黄13×中黄13和冀黄13×开豆16等3个杂交组合P1、P2、F1、F2等4个世代瘪荚率进行联合分离分析.结果表明:在相同的种植条件下,5个亲本的瘪荚率存在显著差异(6.26%~90.96%).3个组合瘪荚率的变异主要由遗传因素引起,且均检测到主基因的存在,但主基因的遗传率均较低,分别为13.40%、29.17%和32.42%.说明大豆荚而不实现象的瘪荚率是典型的数量性状,育种上应以聚合回交及轮回选择等方法聚合有利基因.%The phenomenon of pods without peas is currently one of the major factors influencing summer soybean production in the Huanghuai Valleys. A joint segregation analysis was conducted to investigate hereditary differences of soybean varieties using the useless pod rate as an indicator. The analysis on the useless pod rate of soybean from four generations (P1,P2,F1 and F2) of three cross-combinations (Yudou 25×Zhonghuang 24,Jihuang 13× Zhonghuang 13 and Jihuang 13×Kaidou 16) showed that these five parent varieties differed significantly in the incidence of useless pod rates(6. 26% - 90. 96%). Variations of proportion of useless pod rates mainly caused by genetic factors in the three cross-combinations,and further controlled by major genes,but the major gene heritability was low, ranging from 13. 40% to 32. 42%. This study demonstrated the useless pod rate in pods without peas phenomenon was a typical quantitative hereditary trait,and the soybean breeding should converge beneficial genes through using the convergent backcross method and recurrent selection method.

  2. Mammographic Artifacts on Full-Field Digital Mammography

    OpenAIRE

    Choi, Jae Jeong; Kim, Sung Hun; Kang, Bong Joo; Choi, Byung Gil; Song, ByungJoo; Jung, Haijo

    2013-01-01

    This study investigates the incidence of full-field digital mammographic (FFDM) artifacts with three systems at two institutions and compares the artifacts between two detector types and two grid types. A total of 4,440 direct and 4,142 indirect FFDM images were reviewed by two radiologists, and artifacts were classified as patient related, hardware related, and software processing. The overall incidence of FFDM artifacts was 3.4 % (292/8,582). Patient related artifacts (motion artifacts and ...

  3. Automatic Identification of Artifact-Related Independent Components for Artifact Removal in EEG Recordings.

    Science.gov (United States)

    Zou, Yuan; Nathan, Viswam; Jafari, Roozbeh

    2016-01-01

    Electroencephalography (EEG) is the recording of electrical activity produced by the firing of neurons within the brain. These activities can be decoded by signal processing techniques. However, EEG recordings are always contaminated with artifacts which hinder the decoding process. Therefore, identifying and removing artifacts is an important step. Researchers often clean EEG recordings with assistance from independent component analysis (ICA), since it can decompose EEG recordings into a number of artifact-related and event-related potential (ERP)-related independent components. However, existing ICA-based artifact identification strategies mostly restrict themselves to a subset of artifacts, e.g., identifying eye movement artifacts only, and have not been shown to reliably identify artifacts caused by nonbiological origins like high-impedance electrodes. In this paper, we propose an automatic algorithm for the identification of general artifacts. The proposed algorithm consists of two parts: 1) an event-related feature-based clustering algorithm used to identify artifacts which have physiological origins; and 2) the electrode-scalp impedance information employed for identifying nonbiological artifacts. The results on EEG data collected from ten subjects show that our algorithm can effectively detect, separate, and remove both physiological and nonbiological artifacts. Qualitative evaluation of the reconstructed EEG signals demonstrates that our proposed method can effectively enhance the signal quality, especially the quality of ERPs, even for those that barely display ERPs in the raw EEG. The performance results also show that our proposed method can effectively identify artifacts and subsequently enhance the classification accuracies compared to four commonly used automatic artifact removal methods.

  4. The Ambivalent Ontology of Digital Artifacts

    DEFF Research Database (Denmark)

    Kallinikos, Jannis; Aaltonen, Aleksi; Marton, Attila

    2013-01-01

    Digital artifacts are embedded in wider and constantly shifting ecosystems such that they become increasingly editable, interactive, reprogrammable, and distributable. This state of flux and constant transfiguration renders the value and utility of these artifacts contingent on shifting webs...... of functional relations with other artifacts across specific contexts and organizations. By the same token, it apportions control over the development and use of these artifacts over a range of dispersed stakeholders and makes their management a complex technical and social undertaking. These ideas...... are illustrated with reference to (1) provenance and authenticity of digital documents within the overall context of archiving and social memory and (2) the content dynamics occasioned by the findability of content mediated by Internet search engines. We conclude that the steady change and transfiguration...

  5. Preliminary organizational culture scale focused on artifacts.

    Science.gov (United States)

    Bonavia, Tomas

    2006-12-01

    In this preliminary study, an Organizational Culture Scale was developed to assess cultural artifacts according to Schein's typology (1985). It includes a set of cultural artifacts to measure the extent to which an organization is more or less traditional. A total of 249 managers from a range of different companies responded to the items. Preliminary analysis yielded a one-dimensional scale with 14 items with high internal consistency and homogeneity.

  6. Preliminary organizational culture scale focused on artifacts

    OpenAIRE

    Bonavia, Tomas

    2006-01-01

    In this preliminary study, an organizational culture scale was developed to assess cultural artifacts according to Schein´s typology (1985). It includes a set of cultural artifacts to measure the extent to which an organization is more or less traditional. A total of 249 managers from a range of different companies responded to the items. Preliminary analysis yielded a one-dimensional scale with 14 items with high internal consistency and homogeneity.

  7. Gold-wire artifacts on diagnostic radiographs: A case report

    Energy Technology Data Exchange (ETDEWEB)

    Keestra, Johan Anton Jochum; Jacobs, Reinhilde; Quirynen, Marc [Dept. of Oral Health Sciences, KU Leuven and Dentistry, University Hospitals, KU Leuven, Leuven (Belgium)

    2014-03-15

    This report described a case in which diagnostic radiographs showed irregular dense radiopaque strings and curved lines in the head and neck area. These artifacts could lead to misinterpretation since they may obscure anatomical structures and/or mask critical structures/pathologies. A more detailed history of the patient indicated that these strings originated from a facelift procedure in which a gold-wire technique was used. Considering that such intervention may cause a radiodiagnostic burden, it should be included in the anamnesis prior to radiography.

  8. Analytic solutions of an unclassified artifact /

    Energy Technology Data Exchange (ETDEWEB)

    Trent, Bruce C.

    2012-03-01

    This report provides the technical detail for analytic solutions for the inner and outer profiles of the unclassified CMM Test Artifact (LANL Part Number 157Y-700373, 5/03/2001) in terms of radius and polar angle. Furthermore, analytic solutions are derived for the legacy Sheffield measurement hardware, also in terms of radius and polar angle, using part coordinates, i.e., relative to the analytic profile solutions obtained. The purpose of this work is to determine the exact solution for the “cosine correction” term inherent to measurement with the Sheffield hardware. The cosine correction is required in order to interpret the actual measurements taken by the hardware in terms of an actual part definition, or “knot-point spline definition,” that typically accompanies a component drawing. Specifically, there are two portions of the problem: first an analytic solution must be obtained for any point on the part, e.g., given the radii and the straight lines that define the part, it is required to find an exact solution for the inner and outer profile for any arbitrary polar angle. Next, the problem of the inspection of this part must be solved, i.e., given an arbitrary sphere (representing the inspection hardware) that comes in contact with the part (inner and outer profiles) at any arbitrary polar angle, it is required to determine the exact location of that intersection. This is trivial for the case of concentric circles. In the present case, however, the spherical portion of the profiles is offset from the defined center of the part, making the analysis nontrivial. Here, a simultaneous solution of the part profiles and the sphere was obtained.

  9. Needle-related ultrasound artifacts and their importance in anaesthetic practice.

    Science.gov (United States)

    Reusz, G; Sarkany, P; Gal, J; Csomos, A

    2014-05-01

    Real-time ultrasound guidance for any intervention relies on visualization of needle advancement towards a target. Unfortunately, correct identification of the needle tip is not straightforward, as artifacts always distort the image. The ultrasonic appearance of the needle is often degraded by reverberation, comet tail, side-lobe, beam-width, or bayonet artifacts, which can easily confuse an unprepared operator. Furthermore, the typical needle image, that is, a dot or a straight line (out-of-plane and in-plane approaches, respectively), is also a result of artifacts that hide the real dimensions of the needle. Knowledge and correct interpretation of these artifacts is important for safe practice and is paramount to success when precise needle manipulation is mandatory, for example, when the target is small. In this review, authors discuss the most important needle-related artifacts and provide a physical explanation focusing on implications for everyday practice. Recent advances that allow increased needle visualization and reduction of artifacts are also discussed.

  10. Reconstructing design, explaining artifacts: philosophical reflections on the design and explanation of technical artifacts

    NARCIS (Netherlands)

    De Ridder, G.J.

    2007-01-01

    Philosophers of science have by and large neglected technology. In this book, I have tried to do something about this lacuna by analyzing a few aspects of technical artifacts from a philosophical angle. The project was part of the research program "The Dual Nature of Technical Artifacts" based at De

  11. MPEG recompression detection based on block artifacts

    Science.gov (United States)

    Luo, Weiqi; Wu, Min; Huang, Jiwu

    2008-02-01

    With sophisticated video editing technologies, it is becoming increasingly easy to tamper digital video without leaving visual clues. One of the common tampering operations on video is to remove some frames and then re-encode the resulting video. In this paper, we propose a new method for detecting this type of tampering by exploring the temporal patterns of the block artifacts in video sequences. We show that MPEG compression introduces different block artifacts into various types of frames and that the strength of the block artifacts as a function over time has a regular pattern for a given group of pictures (GOP) structure. When some frames are removed from an MPEG video file and the file is then recompressed, the block artifacts introduced by the previous compression would remain and affect the average of block artifact strength of the recompressed one in such a way that depends on the number of deleted frames and the type of GOP used previously. We propose a feature curve to reveal the compression history of an MPEG video file with a given GOP structure, and use it as evidence to detect tampering. Experimental results evaluated on common video benchmark clips demonstrate the effectiveness of the proposed method.

  12. Mediating Artifact in Teacher Professional Development

    Science.gov (United States)

    Svendsen, Bodil

    2015-07-01

    This article focuses on teacher professional development (TPD) in natural science through the 5E model as mediating artifact. The study was conducted in an upper secondary school, grounded in a school-based intervention research project. My contribution to the field of research on TPD is founded on the hypothesis that teachers would be best facilitated to make their practice more inquiry based if they are provided with a mediating artifact. In this study the artifact is a model 5E, which is a conceptual way of thinking, to help teachers reflect on their practice. The aim is to encourage teachers to make changes themselves, by applying extended use of inquiry into their practice. This mediated artifact could thus be used across different national contexts. The main research question is; how can the 5E model as a mediating artifact enhance TPD? The article addresses the processes of the use of the 5E model and its influence on teachers' perception of the model. This is in order for teachers to conceptualize their goals related to inquiry and scientific thinking, and to solve the problems involved in achieving those goals in their own contexts. The study concludes that, after the intervention, the teachers' approaches and strategies demonstrate greater emphasis on learning.

  13. Artifact Removal from Biosignal using Fixed Point ICA Algorithm for Pre-processing in Biometric Recognition

    Science.gov (United States)

    Mishra, Puneet; Singla, Sunil Kumar

    2013-01-01

    In the modern world of automation, biological signals, especially Electroencephalogram (EEG) and Electrocardiogram (ECG), are gaining wide attention as a source of biometric information. Earlier studies have shown that EEG and ECG show versatility with individuals and every individual has distinct EEG and ECG spectrum. EEG (which can be recorded from the scalp due to the effect of millions of neurons) may contain noise signals such as eye blink, eye movement, muscular movement, line noise, etc. Similarly, ECG may contain artifact like line noise, tremor artifacts, baseline wandering, etc. These noise signals are required to be separated from the EEG and ECG signals to obtain the accurate results. This paper proposes a technique for the removal of eye blink artifact from EEG and ECG signal using fixed point or FastICA algorithm of Independent Component Analysis (ICA). For validation, FastICA algorithm has been applied to synthetic signal prepared by adding random noise to the Electrocardiogram (ECG) signal. FastICA algorithm separates the signal into two independent components, i.e. ECG pure and artifact signal. Similarly, the same algorithm has been applied to remove the artifacts (Electrooculogram or eye blink) from the EEG signal.

  14. A Language of Objects and Artifacts

    DEFF Research Database (Denmark)

    Svabo, Connie

    This is a conceptual inquiry about materiality. It gives an introductory overview to the vocabulary of materiality in a chosen selection of theories. The paper shows a language of artifacts and objects as it is used within practice-based approaches to organizational knowing. The examined intellec......This is a conceptual inquiry about materiality. It gives an introductory overview to the vocabulary of materiality in a chosen selection of theories. The paper shows a language of artifacts and objects as it is used within practice-based approaches to organizational knowing. The examined...... intellectual traditions are interpretive-cultural approaches; activity theory; and sociology of translation. Similarities and differences are presented in the way these three distinct intellectual traditions conceptualize the array of material objects and artifacts which are central in the tales of practice...

  15. Differentiating Pneumothorax from the Common Radiographic Skinfold Artifact.

    Science.gov (United States)

    Kattea, M Obadah; Lababede, Omar

    2015-06-01

    Pneumothorax can be a critical medical condition. The radiographic curvilinear appearance of pneumothorax can be mimicked by a skinfold artifact. Radiographic differentiation of the two entities is achieved in most cases by careful analysis of the characteristics of the linear shadow and its course. A thin, sharply defined opaque density representing the visceral pleura is the hallmark of pneumothorax. The added density of a skinfold presents as a broad opacity, which is outlined laterally by a sharply defined lucent line as a result of the Mach band effect and adjacent air. Unlike pneumothorax, a skinfold produces a line that does not follow the expected course of visceral pleura. Additional features, such as the absence of increased lucency laterally and the projection of lung markings across the curvilinear shadow, can help in the correct identification of skinfolds. Repeating the chest radiograph or using other imaging modalities can be considered in difficult cases.

  16. Studying the Creation of Design Artifacts

    DEFF Research Database (Denmark)

    Davis, Christopher J.; Hevner, Ala n R.; Weber, Barbara

    2016-01-01

    and information systems represents a highly interconnected locus in which both the generative processes of building design artifacts and articulating constructs used to evaluate their quality take place. We address this interconnectedness with an extended process-oriented research design enabling multi......-modal neurophysiological data analyses. We posit that our research will provide more comprehensive assessments of the efficacy of design processes and the evaluation of the qualities of the resulting design artifacts.......As software and information systems (IS) increase in functional sophistication, perceptions of IS quality are changing. Moving beyond issues of performance efficiency, essential qualities such as fitness for purpose, sustainability, and overall effectiveness become more complex. Creating software...

  17. Artifacts of Functional Electrical Stimulation on Electromyograph

    Institute of Scientific and Technical Information of China (English)

    DUAN Ren-quan; ZHANG Ding-guo

    2014-01-01

    The purpose of this study is to investigate different factors of the artifact in surface electromyography (EMG) signal caused by functional electrical stimulation (FES). The factors investigated include the size of stimulation electrode pads, the amplitude, frequency, and pulse width of the stimulation waveform and the detecting electrode points. We calculate the root mean square (RMS) of EMG signal to analyze the effect of these factors on the M-wave properties. The results indicate that the M-wave mainly depends on the stimulation amplitude and the distribution of detecting electrodes, but not on the other factors. This study can assist the reduction of artifact and the selection of detecting electrode points.

  18. [BODIES ARTIFACTS AND ANATOMICAL MODELS].

    Science.gov (United States)

    Aruta, Alessandro

    2015-01-01

    Through three different museological approaches, diachronically arranged, the essay intends to introduce some pertinent questions related to the topic of the conference "Bodies and Anatomy: the corpses in the museums from Ruysch to Von Hagens. The first item analyzes a recent line of British museological studies, treating mainly medical British museums of the XVIII and XIX century, with intriguing developments arriving up to nowadays. A second point illustrates several aspects with regards to the donation and the arrangement of the morbid specimina Luigi Gedda collection, coming from the CSS Mendel of Rome to the Museum of Pathological Anatomy of Sapienza University of Rome. Finally, in a crossover between the previous points, it will be presented some recent studies regarding the employment of new communication technologies in the scientific and medical museology.

  19. Mirror Image Video Artifact: An Under-Reported Digital Video-EEG Artifact.

    Science.gov (United States)

    Babcock, Michael A; Levis, William H; Bhatt, Amar B

    2017-01-01

    Synchronous video recording can be helpful in EEG recordings, especially in recognition of seizures and in rejection of artifacts. However, video recordings themselves are also subject to the risk of contamination by artifacts. We report a unique case in which a digital video artifact was identified, occurring during synchronous video-EEG recording, albeit independently of the EEG tracing itself. A synchronous digital video-EEG recording was performed on a 67-year-old male who presented in focal motor status epilepticus. During the initial review of the data, right-sided abnormalities on EEG apparently corresponded with (ipsilateral) right arm motor activity on video, suggesting a nonsensical anatomical localization. However, review of the patient's chart and discussion with the EEG technologist led to the recognition that the video data recorded a mirror image of the true findings of left arm motor activity. Review of the software settings led to the discovery that the video recording was inverted along the vertical axis, leading to mirror image video artifact. Recognition of this video artifact allowed for accurate interpretation of the study-that right hemispheric EEG abnormalities correlated appropriately with (contralateral) left arm twitching. Effective communication between the EEG reading physician, the treating team, and the EEG technologist is critical for recognition of such artifacts, for proper EEG interpretation, and for appropriate patient management. Mirror image video artifact affirms that bedside evaluation, astute technologists, and attentive EEG reading physicians remain important, even in the presence of video recording.

  20. PIXE Analysis of Ceramic Artifacts

    Science.gov (United States)

    High, Elizabeth; Lamm, Larry; Schurr, Mark; Stech, Edward; Wiescher, Michael

    2009-10-01

    Particle Induced X-ray Emissions, or PIXE, is a nuclear physics technique used as a non-destructive material analysis method which gives a detailed and comprehensive profile of the elemental composition of a target. Using the University of Notre Dame KN and FN accelerators in the ISNAP laboratory a beam of particles, here protons, is accelerated and used to knock out electrons from lower orbitals within the target resulting in characteristic X-rays. Under optimum operating conditions data from PIXE can not only give information about which elements are present in a sample but also their relative abundances in parts per million. In a previous run done in collaboration with the Anthropology Department at the University of Notre Dame pottery shards from the Collier Lodge, located in northwest Indiana, were analyzed and only relative abundances were able to be compared between samples. We are now implementing a new setup into the beam-line which will incorporate the ability to take Rutherford Back Scattering, or RBS, measurements of the beam during the PIXE runs, which will allow for a standard normalization for the runs and give the facility the ability to acquire a more absolute and quantitative analysis of the data. Initial results using the same pottery shards as a comparative data set will be presented.

  1. Conceptual Model of Artifacts for Design Science Research

    DEFF Research Database (Denmark)

    Bækgaard, Lars

    2015-01-01

    We present a conceptual model of design science research artifacts. The model views an artifact at three levels. At the artifact level a selected artifact is viewed as a combination of material and immaterial aspects and a set of representations hereof. At the design level the selected artifact...... is viewed through its design in terms of descriptions, models, prototypes etc. At the knowledge level the selected artifact is viewed through ontologies, categories and various types of relevant knowledge. The model is based on description...

  2. Conceptual Model of Artifacts for Design Science Research

    DEFF Research Database (Denmark)

    Bækgaard, Lars

    2015-01-01

    We present a conceptual model of design science research artifacts. The model views an artifact at three levels. At the artifact level a selected artifact is viewed as a combination of material and immaterial aspects and a set of representations hereof. At the design level the selected artifact...... is viewed through its design in terms of descriptions, models, prototypes etc. At the knowledge level the selected artifact is viewed through ontologies, categories and various types of relevant knowledge. The model is based on description...

  3. A Social Language of Objects and Artifacts

    DEFF Research Database (Denmark)

    Svabo, Connie

    2007-01-01

    This paper is an inquiry about design. It gives an introductory overview of the vocabulary of 'materiality', which is used by a chosen selection of social theories. The paper shows a language of artifacts and objjects as it is used within practice-based approaches to knowing in organization  ...

  4. On the reduction of hypercubic lattice artifacts

    CERN Document Server

    De Soto, F

    2007-01-01

    This note presents a comparative study of various options to reduce the errors coming from the discretization of a Quantum Field Theory in a lattice with hypercubic symmetry. We show that it is possible to perform an extrapolation towards the continuum which is able to eliminate systematically the artifacts which break the O(4) symmetry.

  5. Artifacts reduction in VIR/Dawn data

    Science.gov (United States)

    Carrozzo, F. G.; Raponi, A.; De Sanctis, M. C.; Ammannito, E.; Giardino, M.; D'Aversa, E.; Fonte, S.; Tosi, F.

    2016-12-01

    Remote sensing images are generally affected by different types of noise that degrade the quality of the spectral data (i.e., stripes and spikes). Hyperspectral images returned by a Visible and InfraRed (VIR) spectrometer onboard the NASA Dawn mission exhibit residual systematic artifacts. VIR is an imaging spectrometer coupling high spectral and spatial resolutions in the visible and infrared spectral domain (0.25-5.0 μm). VIR data present one type of noise that may mask or distort real features (i.e., spikes and stripes), which may lead to misinterpretation of the surface composition. This paper presents a technique for the minimization of artifacts in VIR data that include a new instrument response function combining ground and in-flight radiometric measurements, correction of spectral spikes, odd-even band effects, systematic vertical stripes, high-frequency noise, and comparison with ground telescopic spectra of Vesta and Ceres. We developed a correction of artifacts in a two steps process: creation of the artifacts matrix and application of the same matrix to the VIR dataset. In the approach presented here, a polynomial function is used to fit the high frequency variations. After applying these corrections, the resulting spectra show improvements of the quality of the data. The new calibrated data enhance the significance of results from the spectral analysis of Vesta and Ceres.

  6. Kinematic artifacts in prestack depth migration.

    NARCIS (Netherlands)

    Stolk, C.C.; Symes, W.W.

    2004-01-01

    Strong refraction of waves in the migration velocity model introduces kinematic artifacts¿coherent events not corresponding to actual reflectors¿into the image volumes produced by prestack depth migration applied to individual data bins. Because individual bins are migrated independently, the migrat

  7. A constructivist approach to artifact development

    DEFF Research Database (Denmark)

    Skytte, Hans

    2008-01-01

    . The main result of the study shows that the concepts used (identity, image, organizational field etc.) to analyze the companies construct of the concepts, are linked in recursive patterns. This means that a company's artifact development takes place in recursive patterns consisting of concepts, meanings...

  8. Information Design for Visualizing History Museum Artifacts

    Science.gov (United States)

    Chen, Yulin; Lai, Tingsheng; Yasuda, Takami; Yokoi, Shigeki

    2011-01-01

    In the past few years, museum visualization systems have become a hot topic that attracts many researchers' interests. Several systems provide Web services for browsing museum collections through the Web. In this paper, we proposed an intelligent museum system for history museum artifacts, and described a study in which we enable access to China…

  9. Model of Image Artifacts from Dust Particles

    Science.gov (United States)

    Willson, Reg

    2008-01-01

    A mathematical model of image artifacts produced by dust particles on lenses has been derived. Machine-vision systems often have to work with camera lenses that become dusty during use. Dust particles on the front surface of a lens produce image artifacts that can potentially affect the performance of a machine-vision algorithm. The present model satisfies a need for a means of synthesizing dust image artifacts for testing machine-vision algorithms for robustness (or the lack thereof) in the presence of dust on lenses. A dust particle can absorb light or scatter light out of some pixels, thereby giving rise to a dark dust artifact. It can also scatter light into other pixels, thereby giving rise to a bright dust artifact. For the sake of simplicity, this model deals only with dark dust artifacts. The model effectively represents dark dust artifacts as an attenuation image consisting of an array of diffuse darkened spots centered at image locations corresponding to the locations of dust particles. The dust artifacts are computationally incorporated into a given test image by simply multiplying the brightness value of each pixel by a transmission factor that incorporates the factor of attenuation, by dust particles, of the light incident on that pixel. With respect to computation of the attenuation and transmission factors, the model is based on a first-order geometric (ray)-optics treatment of the shadows cast by dust particles on the image detector. In this model, the light collected by a pixel is deemed to be confined to a pair of cones defined by the location of the pixel s image in object space, the entrance pupil of the lens, and the location of the pixel in the image plane (see Figure 1). For simplicity, it is assumed that the size of a dust particle is somewhat less than the diameter, at the front surface of the lens, of any collection cone containing all or part of that dust particle. Under this assumption, the shape of any individual dust particle artifact

  10. Artifacts for Calibration of Submicron Width Measurements

    Science.gov (United States)

    Grunthaner, Frank; Grunthaner, Paula; Bryson, Charles, III

    2003-01-01

    Artifacts that are fabricated with the help of molecular-beam epitaxy (MBE) are undergoing development for use as dimensional calibration standards with submicron widths. Such standards are needed for calibrating instruments (principally, scanning electron microscopes and scanning probe microscopes) for measuring the widths of features in advanced integrated circuits. Dimensional calibration standards fabricated by an older process that involves lithography and etching of trenches in (110) surfaces of single-crystal silicon are generally reproducible to within dimensional tolerances of about 15 nm. It is anticipated that when the artifacts of the present type are fully developed, their critical dimensions will be reproducible to within 1 nm. These artifacts are expected to find increasing use in the semiconductor-device and integrated- circuit industries as the width tolerances on semiconductor devices shrink to a few nanometers during the next few years. Unlike in the older process, one does not rely on lithography and etching to define the critical dimensions. Instead, one relies on the inherent smoothness and flatness of MBE layers deposited under controlled conditions and defines the critical dimensions as the thicknesses of such layers. An artifact of the present type is fabricated in two stages (see figure): In the first stage, a multilayer epitaxial wafer is grown on a very flat substrate. In the second stage, the wafer is cleaved to expose the layers, then the exposed layers are differentially etched (taking advantage of large differences between the etch rates of the different epitaxial layer materials). The resulting structure includes narrow and well-defined trenches and a shelf with thicknesses determined by the thicknesses of the epitaxial layers from which they were etched. Eventually, it should be possible to add a third fabrication stage in which durable, electronically inert artifacts could be replicated in diamondlike carbon from a master made by

  11. Social web artifacts for boosting recommenders theory and implementation

    CERN Document Server

    Ziegler, Cai-Nicolas

    2013-01-01

    Recommender systems, software programs that learn from human behavior and make predictions of what products we are expected to appreciate and purchase, have become an integral part of our everyday life. They proliferate across electronic commerce around the globe and exist for virtually all sorts of consumable goods, such as books, movies, music, or clothes. At the same time, a new evolution on the Web has started to take shape, commonly known as the “Web 2.0” or the “Social Web”: Consumer-generated media has become rife, social networks have emerged and are pulling significant shares of Web traffic. In line with these developments, novel information and knowledge artifacts have become readily available on the Web, created by the collective effort of millions of people. This textbook presents approaches to exploit the new Social Web fountain of knowledge, zeroing in first and foremost on two of those information artifacts, namely classification taxonomies and trust networks. These two are used to impr...

  12. Elimination of motion and pulsation artifacts using BLADE sequences in shoulder MR imaging

    Energy Technology Data Exchange (ETDEWEB)

    Lavdas, E.; Zaloni, E. [Technological Education Institute of Athens, Greece, Department of Medical Radiological Technologists, Athens (Greece); Vlychou, M.; Vassiou, K.; Fezoulidis, I. [University of Thessaly, Department of Radiology, Faculty of Medicine, Larissa (Greece); Tsagkalis, A. [IASO Hospital, Department of Orthopedics, Larissa (Greece); Dailiana, Z. [University of Thessaly, Department of Orthopedics, Faculty of Medicine, Larissa (Greece)

    2015-11-15

    To evaluate the ability of proton-density with fat-suppression BLADE (proprietary name for periodically rotated overlapping parallel lines with enhanced reconstruction in MR systems from Siemens Healthcare, PDFS BLADE) and turbo inversion recovery magnitude-BLADE (TIRM BLADE) sequences to reduce motion and pulsation artifacts in shoulder magnetic resonance examinations. Forty-one consecutive patients who had been routinely scanned for shoulder examination participated in the study. The following pairs of sequences with and without BLADE were compared: (a) Oblique coronal proton-density sequence with fat saturation of 25 patients and (b) oblique sagittal T2 TIRM-weighed sequence of 20 patients. Qualitative analysis was performed by two experienced radiologists. Image motion and pulsation artifacts were also evaluated. In oblique coronal PDFS BLADE sequences, motion artifacts have been significantly eliminated, even in five cases of non-diagnostic value with conventional imaging. Similarly, in oblique sagittal T2 TIRM BLADE sequences, image quality has been improved, even in six cases of non-diagnostic value with conventional imaging. Furthermore, flow artifacts have been improved in more than 80% of all the cases. The use of BLADE sequences is recommended in shoulder imaging, especially in uncooperative patients because it effectively eliminates motion and pulsation artifacts. (orig.)

  13. Smoking Artifacts as Indicators of Homophily, Attraction, and Credibility.

    Science.gov (United States)

    Hickson, Mark, III; And Others

    1979-01-01

    Describes a study of the influence of smoking artifacts on the perceptions of a source's homophily, interpersonal attraction, and credibility. Significant differences were found based upon the type of smoking artifact used and the sex of the subject. (JMF)

  14. Artifacts and pitfalls of high-resolution CT scans.

    Science.gov (United States)

    Hahn, F J; Chu, W K; Anderson, J C; Dobry, C A

    1985-01-01

    Artifacts on CT images have been observed since the introduction of CT scanners. Some artifacts have been corrected with the improvement of technology and better understanding of the image formation and reconstruction algorithms. Some artifacts, however, are still observable in state-of-the-art high-resolution scans. Many investigations on CT artifacts have been reported. Some artifacts are obvious and some are similar to patterns commonly associated with pathological conditions. The present report summarizes some of the causes of artifacts and presents some artifacts that mimic pathology on clinical scans of the head and spine. It is the intention of this report to bring these artifacts and potential pitfalls to the attention of the radiologists so that misinterpretation can be avoided.

  15. Teaching and Learning the Nature of Technical Artifacts

    Science.gov (United States)

    Frederik, Ineke; Sonneveld, Wim; de Vries, Marc J.

    2011-01-01

    Artifacts are probably our most obvious everyday encounter with technology. Therefore, a good understanding of the nature of technical artifacts is a relevant part of technological literacy. In this article we draw from the philosophy of technology to develop a conceptualization of technical artifacts that can be used for educational purposes.…

  16. Connecting Student and Subject Matter: The Cultural Artifact Discussion Assignment

    Science.gov (United States)

    Smith-Sanders, Alane K.

    2008-01-01

    This article presents a class activity where students work in dyads to select an artifact related to a course topic and, using this artifact, develop discussion questions to engage their classmates. This cultural artifact assignment is intended to, in part, answer John Dewey's call to cultivate connections between subject matter and life…

  17. Supporting Knowledge Transfer through Decomposable Reasoning Artifacts

    Energy Technology Data Exchange (ETDEWEB)

    Pike, William A.; May, Richard A.; Turner, Alan E.

    2007-01-03

    Technology to support knowledge transfer and cooperative inquiry must offer its users the ability to effectively interpret knowledge structures produced by collaborators. Communicating the reasoning processes that underlie a finding is one method for enhancing interpretation, and can result in more effective evaluation and application of shared knowledge. In knowledge management tools, interpretation is aided by creating knowledge artifacts that can expose their provenance to scrutiny and that can be transformed into diverse representations that suit their consumers’ perspectives and preferences. We outline the information management needs of inquiring communities characterized by hypothesis generation tasks, and propose a model for communication, based in theories of hermeneutics, semiotics, and abduction, in which knowledge structures can be decomposed into the lower-level reasoning artifacts that produced them. We then present a proof-of-concept implementation for an environment to support the capture and communication of analytic products, with emphasis on the domain of intelligence analysis.

  18. MORAL TECHNIQUES. FORENSIC ANTHROPOLOGY AND ITS ARTIFACTS FOR DOING GOOD

    Directory of Open Access Journals (Sweden)

    GABRIEL GATTI

    2013-01-01

    Full Text Available In many of its applications forensic anthropology is a singular discipline, midway between a bare techno-scientific exercise and a militant involvement in overcoming situations marked by human rights violations. Today, riding on an intense and transnational wave of humanitarian sensitivity, forensic anthropology has acquired a significant scientific, moral and media status, and has become a front line scientific-technical practice in the human rights field at the planetary level. This text, which analyzes some of the artifacts with which forensic anthropology represents and works on its object, aims to understand this discipline through the concept of moral technique, which, in my understanding, captures the particular tensions of this form of working for good.

  19. Artifacts Of Spectral Analysis Of Instrument Readings

    Science.gov (United States)

    Wise, James H.

    1995-01-01

    Report presents experimental and theoretical study of some of artifacts introduced by processing outputs of two nominally identical low-frequency-reading instruments; high-sensitivity servo-accelerometers mounted together and operating, in conjunction with signal-conditioning circuits, as seismometers. Processing involved analog-to-digital conversion with anti-aliasing filtering, followed by digital processing including frequency weighting and computation of different measures of power spectral density (PSD).

  20. [Hybrid interpolation for CT metal artifact reducing].

    Science.gov (United States)

    Yu, Xiao-e; Li, Chan-juan; Chen, Wu-fan

    2009-01-01

    Numerous interpolation-based methods have been described for reducing metal artifacts in CT images, but due to the limit of the interpolation methods, interpolation alone often fails to meet the clinical demands. In this paper, we describe the use of quartic polynomial interpolation in reconstruction of the images of the metal implant followed by linear interpolation to eliminate the streaks. The two interpolation methods are combined according to their given weights to achieve good results.

  1. Panning artifacts in digital pathology images

    Science.gov (United States)

    Avanaki, Ali R. N.; Lanciault, Christian; Espig, Kathryn S.; Xthona, Albert; Kimpe, Tom R. L.

    2017-03-01

    In making a pathologic diagnosis, a pathologist uses cognitive processes: perception, attention, memory, and search (Pena and Andrade-Filho, 2009). Typically, this involves focus while panning from one region of a slide to another, using either a microscope in a traditional workflow or software program and display in a digital pathology workflow (DICOM Standard Committee, 2010). We theorize that during panning operation, the pathologist receives information important to diagnosis efficiency and/or correctness. As compared to an optical microscope, panning in a digital pathology image involves some visual artifacts due to the following: (i) the frame rate is finite; (ii) time varying visual signals are reconstructed using imperfect zero-order hold. Specifically, after pixel's digital drive is changed, it takes time for a pixel to emit the expected amount of light. Previous work suggests that 49% of navigation is conducted in low-power/overview with digital pathology (Molin et al., 2015), but the influence of display factors has not been measured. We conducted a reader study to establish a relationship between display frame rate, panel response time, and threshold panning speed (above which the artifacts become noticeable). Our results suggest visual tasks that involve tissue structure are more impacted by the simulated panning artifacts than those that only involve color (e.g., staining intensity estimation), and that the panning artifacts versus normalized panning speed has a peak behavior which is surprising and may change for a diagnostic task. This is work in progress and our final findings should be considered in designing future digital pathology systems.

  2. Voting strategy for artifact reduction in digital breast tomosynthesis.

    Science.gov (United States)

    Wu, Tao; Moore, Richard H; Kopans, Daniel B

    2006-07-01

    Artifacts are observed in digital breast tomosynthesis (DBT) reconstructions due to the small number of projections and the narrow angular range that are typically employed in tomosynthesis imaging. In this work, we investigate the reconstruction artifacts that are caused by high-attenuation features in breast and develop several artifact reduction methods based on a "voting strategy." The voting strategy identifies the projection(s) that would introduce artifacts to a voxel and rejects the projection(s) when reconstructing the voxel. Four approaches to the voting strategy were compared, including projection segmentation, maximum contribution deduction, one-step classification, and iterative classification. The projection segmentation method, based on segmentation of high-attenuation features from the projections, effectively reduces artifacts caused by metal and large calcifications that can be reliably detected and segmented from projections. The other three methods are based on the observation that contributions from artifact-inducing projections have higher value than those from normal projections. These methods attempt to identify the projection(s) that would cause artifacts by comparing contributions from different projections. Among the three methods, the iterative classification method provides the best artifact reduction; however, it can generate many false positive classifications that degrade the image quality. The maximum contribution deduction method and one-step classification method both reduce artifacts well from small calcifications, although the performance of artifact reduction is slightly better with the one-step classification. The combination of one-step classification and projection segmentation removes artifacts from both large and small calcifications.

  3. Detection and Removal of Artifacts in Astronomical Images

    CERN Document Server

    Desai, Shantanu; Bertin, Emmanuel; Kummel, Martin; Wetzstein, Michael

    2016-01-01

    Astronomical images from optical photometric surveys are typically contaminated with transient artifacts such as cosmic rays, satellite trails and scattered light. We have developed and tested an algorithm that removes these artifacts using a deep, artifact free, static sky coadd image built up through the median combination of point spread function (PSF) homogenized, overlapping single epoch images. Transient artifacts are detected and masked in each single epoch image through comparison with an artifact free, PSF-matched simulated image that is constructed using the PSF-corrected, model fitting catalog from the artifact free coadd image together with the position variable PSF model of the single epoch image. This approach works well not only for cleaning single epoch images with worse seeing than the PSF homogenized coadd, but also the traditionally much more challenging problem of cleaning single epoch images with better seeing. In addition to masking transient artifacts, we have developed an interpolation...

  4. Is the Concept of "Dignity" Useless to Life Ethics?%“尊严”概念于生命伦理学无用吗?

    Institute of Scientific and Technical Information of China (English)

    韩跃红

    2012-01-01

    “尊严”于生命伦理学有用还是无用,是当前国际生命伦理学界的一个争论焦点。本文在回应“无用论”的同时,论证指出:第一,“尊严”不能被等同于“尊重”,它有超出“尊重”的内涵“盈余”;第二,在生命伦理学中,人的“尊严”不仅有用而且有大用,它是生命伦理学的基本价值观,其所内涵的“人的生命尊严”就是生命伦理学的核心价值。护卫生命的尊严就是生命伦理学的宗旨和使命。第三,“尊严”在实际应用时一般需要过渡和转化,即从价值观过渡和转化为根本伦理原则和若干基本原则;从价值转化为道德权利和法律权利。%Whether the concept of "human dignity" is useful or useless in the study of life ethics has be- come a main argument in the international academia of life ethics currently. This paper argues against the opin- ion that "Dignity is a useless concept in the study of life ethics". The paper holds that the concept of "dignity" cannot be viewed as an equivalent of "respect" because it has much broader and more profound surplus conno- tations than the latter. In the second place, the concept of "human dignity" in the study of life ethics is not merely being useful, but being of "great use" because it denotes the very basic values of life ethics and the con- notation of "human dignity of life" serves as one of its core values. Therefore, maintaining the dignity of life is the key purpose and mission of life ethics. Thirdly, the concept of "dignity" in practical ethics studies needs to be transmitted and transformed, in which life values are transmitted and transformed into the cardinal ethic prin- ciple and other basic principles and, in turn, into moral rights and legal rights.

  5. Metal artifact suppression in megavoltage computed tomography

    Science.gov (United States)

    Schreiner, L. John; Rogers, Myron; Salomons, Greg; Kerr, Andrew

    2005-04-01

    There has been considerable interest in megavoltage CT (MVCT) imaging associated with the development of image guided radiation therapy. It is clear that MVCT can provide good image quality for patient setup verification with soft tissue contrast much better than noted in conventional megavoltage portal imaging. In addition, it has been observed that MVCT images exhibit considerably reduced artifacts surrounding metal implants (e.g., surgical clips, hip implants, dental fillings) compared to conventional diagnostic CT images (kVCT). When encountered, these artifacts greatly limit the usefulness of kVCT images, and a variety of solutions have been proposed to remove the artifacts, but these have met with only partial success. In this paper, we investigate the potential for CT imaging in regions surrounding metal implants using high-energy photons from a Cobalt-60 source and from a 4 MV linear accelerator. MVCT and kVCT images of contrast phantoms and a phantom containing a hip prosthesis are compared and analysed. We show that MVCT scans provide good fidelity for CT number quantification in the high-density regions of the images, and in the regions immediately adjacent to the metal implants. They also provide structural details within the high-density inserts and implants. Calculations will show that practical clinical MVCT imaging, able to detect 3% contrast objects, should be achievable with doses of about 2.5cGy. This suggests that MVCT not only has a role in radiotherapy treatment planning and guidance, but may also be indicated for surgical guidance and follow-up in regions where metal implants cannot be avoided.

  6. Accessing Cultural Artifacts Through Digital Companions

    DEFF Research Database (Denmark)

    Rehm, Matthias; Jensen, Martin Lynge

    2016-01-01

    This paper presents a study that explores how the introduction of a digital companion agent for a museum exploration game changes children’s engagement with the presented artworks. To this end, a mobile application was developed featuring a monster agent that has eaten the artworks, which the chi...... the children had now to find in the museum. Results show that in comparison to the paper-based version of the exploration game, children engaged in more interactions with the actual cultural artifacts and showed a significantly higher retention rate for details of the involved artworks....

  7. Hair product artifact in magnetic resonance imaging.

    Science.gov (United States)

    Chenji, Sneha; Wilman, Alan H; Mah, Dennell; Seres, Peter; Genge, Angela; Kalra, Sanjay

    2017-01-01

    The presence of metallic compounds in facial cosmetics and permanent tattoos may affect the quality of magnetic resonance imaging. We report a case study describing a signal artifact due to the use of a leave-on powdered hair dye. On reviewing the ingredients of the product, it was found to contain several metallic compounds. In lieu of this observation, we suggest that MRI centers include the use of metal- or mineral-based facial cosmetics or hair products in their screening protocols. Copyright © 2016 Elsevier Inc. All rights reserved.

  8. Mathematical models frame environmental dispute [Review of the article Useless arithmetic: Ten points to ponder when using mathematical models in environmental decision making

    Science.gov (United States)

    Lamb, Berton Lee; Burkardt, Nina

    2008-01-01

    When Linda Pilkey- Jarvis and Orrin Pilkey state in their article, "Useless Arithmetic," that "mathematical models are simplified, generalized representations of a process or system," they probably do not mean to imply that these models are simple. Rather, the models are simpler than nature and that is the heart of the problem with predictive models. We have had a long professional association with the developers and users of one of these simplifications of nature in the form of a mathematical model known as Physical Habitat Simulation (PHABSIM), which is part of the Instream Flow Incremental Methodology (IFIM). The IFIM is a suite of techniques, including PHABSIM, that allows the analyst to incorporate hydrology , hydraulics, habitat, water quality, stream temperature, and other variables into a tradeoff analysis that decision makers can use to design a flow regime to meet management objectives (Stalnaker et al. 1995). Although we are not the developers of the IFIM, we have worked with those who did design it, and we have tried to understand how the IFIM and PHABSIM are actually used in decision making (King, Burkardt, and Clark 2006; Lamb 1989).

  9. Recognizing scientific artifacts in biomedical literature.

    Science.gov (United States)

    Groza, Tudor; Hassanzadeh, Hamed; Hunter, Jane

    2013-01-01

    Today's search engines and digital libraries offer little or no support for discovering those scientific artifacts (hypotheses, supporting/contradicting statements, or findings) that form the core of scientific written communication. Consequently, we currently have no means of identifying central themes within a domain or to detect gaps between accepted knowledge and newly emerging knowledge as a means for tracking the evolution of hypotheses from incipient phases to maturity or decline. We present a hybrid Machine Learning approach using an ensemble of four classifiers, for recognizing scientific artifacts (ie, hypotheses, background, motivation, objectives, and findings) within biomedical research publications, as a precursory step to the general goal of automatically creating argumentative discourse networks that span across multiple publications. The performance achieved by the classifiers ranges from 15.30% to 78.39%, subject to the target class. The set of features used for classification has led to promising results. Furthermore, their use strictly in a local, publication scope, ie, without aggregating corpus-wide statistics, increases the versatility of the ensemble of classifiers and enables its direct applicability without the necessity of re-training.

  10. Single authentication: exposing weighted splining artifacts

    Science.gov (United States)

    Ciptasari, Rimba W.

    2016-05-01

    A common form of manipulation is to combine parts of the image fragment into another different image either to remove or blend the objects. Inspired by this situation, we propose a single authentication technique for detecting traces of weighted average splining technique. In this paper, we assume that image composite could be created by joining two images so that the edge between them is imperceptible. The weighted average technique is constructed from overlapped images so that it is possible to compute the gray level value of points within a transition zone. This approach works on the assumption that although splining process leaves the transition zone smoothly. They may, nevertheless, alter the underlying statistics of an image. In other words, it introduces specific correlation into the image. The proposed idea dealing with identifying these correlations is to generate an original model of both weighting function, left and right functions, as references to their synthetic models. The overall process of the authentication is divided into two main stages, which are pixel predictive coding and weighting function estimation. In the former stage, the set of intensity pairs {Il,Ir} is computed by exploiting pixel extrapolation technique. The least-squares estimation method is then employed to yield the weighted coefficients. We show the efficacy of the proposed scheme on revealing the splining artifacts. We believe that this is the first work that exposes the image splining artifact as evidence of digital tampering.

  11. Ontological System for Context Artifacts and Resources

    Science.gov (United States)

    Huang, T.; Chung, N. T.; Mukherjee, R. M.

    2012-12-01

    The Adaptive Vehicle Make (AVM) program is a portfolio of programs, managed by the Defense Advanced Research Projects Agency (DARPA). It was established to revolutionize how DoD designs, verifies, and manufactures complex defense systems and vehicles. The Component, Context, and Manufacturing Model Library (C2M2L; pronounced "camel") seeks to develop domain-specific models needed to enable design, verification, and fabrication of the Fast Adaptable Next-Generation (FANG) infantry fighting vehicle using in its overall infrastructure. Terrain models are being developed to represent the surface/fluid that an amphibious infantry fighting vehicle would traverse, ranging from paved road surfaces to rocky, mountainous terrain, slope, discrete obstacles, mud, sand snow, and water fording. Context models are being developed to provide additional data for environmental factors, such as: humidity, wind speed, particulate presence and character, solar radiation, cloud cover, precipitation, and more. The Ontological System for Context Artifacts and Resources (OSCAR) designed and developed at the Jet Propulsion Laboratory is semantic web data system that enables context artifacts to be registered and searched according to their meaning, rather than indexed according to their syntactic structure alone (as in the case for traditional search engines). The system leverages heavily on the Semantic Web for Earth and Environmental Terminology (SWEET) ontologies to model physical terrain environment and context model characteristics. In this talk, we focus on the application of the SWEET ontologies and the design of the OSCAR system architecture.

  12. Anti-scatter grid artifact elimination for high resolution x-ray imaging CMOS detectors

    Science.gov (United States)

    Rana, R.; Singh, V.; Jain, A.; Bednarek, D. R.; Rudin, S.

    2015-03-01

    Higher resolution in dynamic radiological imaging such as angiography is increasingly being demanded by clinicians; however, when standard anti-scatter grids are used with such new high resolution detectors, grid-line artifacts become more apparent resulting in increased structured noise that may overcome the contrast signal improvement benefits of the scatter-reducing grid. Although grid-lines may in theory be eliminated by dividing the image of a patient taken with the grid by a flat-field image taken with the grid obtained prior to the clinical image, unless the remaining additive scatter contribution is subtracted in real-time from the dynamic clinical image sequence before the division by the reference image, severe grid-line artifacts may remain. To investigate grid-line elimination, a stationary Smit Röntgen X-ray grid (line density: 70 lines/cm, grid ratio 13:1) was used with both a 75 micron-pixel CMOS detector and a standard 194 micron-pixel flat panel detector (FPD) to image an artery block insert placed in a modified uniform frontal head phantom for a 20 x 20cm FOV (approximately). Contrast and contrast-to-noise ratio (CNR) were measured with and without scatter subtraction prior to grid-line correction. The fixed pattern noise caused by the grid was substantially higher for the CMOS detector compared to the FPD and caused a severe reduction of CNR. However, when the scatter subtraction corrective method was used, the removal of the fixed pattern noise (grid artifacts) became evident resulting in images with improved CNR.

  13. Contrast Reversal of Topography Artifacts in a Transmission SNOM

    Institute of Scientific and Technical Information of China (English)

    LI Zhi; WANG Shu-Feng; ZHANG Jia-Sen; GONG Qi-Huang

    2005-01-01

    @@ We demonstrate the contrast reversal behaviour of topography artifacts by changing the diameter of the collection diaphragm in a transmission scanning near-field optical microscopy (SNOM). This originates from the change of the approach curves. Such contrast reversal phenomenon is used to distinguish the artifact signal from the true optical signal of the SNOM image. We also show that continuously changing the diaphragm to a proper diameter can greatly reduce topography artifacts.

  14. Contrast artifacts in tapping tip atomic force microscopy

    DEFF Research Database (Denmark)

    Kyhle, Anders; Sørensen, Alexis Hammer; Zandbergen, Julie Bjerring;

    1998-01-01

    When recording images with an atomic force microscope using the resonant vibrating cantilever mode, surprising strange results are often achieved. Typical artifacts are strange contours, unexpected height shifts, and sudden changes of the apparent resolution in the acquired images. Such artifacts...... interaction. The oscillating cantilever will be in a specific swing mode according to which type of interaction is dominating, and it is the switching between these modes that is responsible for a range of artifacts observed during image acquisition. This includes the artifact often referred to as "contrast...

  15. Automatic identification of artifacts in electrodermal activity data.

    Science.gov (United States)

    Taylor, Sara; Jaques, Natasha; Chen, Weixuan; Fedor, Szymon; Sano, Akane; Picard, Rosalind

    2015-01-01

    Recently, wearable devices have allowed for long term, ambulatory measurement of electrodermal activity (EDA). Despite the fact that ambulatory recording can be noisy, and recording artifacts can easily be mistaken for a physiological response during analysis, to date there is no automatic method for detecting artifacts. This paper describes the development of a machine learning algorithm for automatically detecting EDA artifacts, and provides an empirical evaluation of classification performance. We have encoded our results into a freely available web-based tool for artifact and peak detection.

  16. Picking Up Artifacts: Storyboarding as a Gateway to Reuse

    Science.gov (United States)

    Wahid, Shahtab; Branham, Stacy M.; Cairco, Lauren; McCrickard, D. Scott; Harrison, Steve

    Storyboarding offers designers the opportunity to illustrate a visual narrative of use. Because designers often refer to past ideas, we argue storyboards can be constructed by reusing shared artifacts. We present a study in which we explore how designers reuse artifacts consisting of images and rationale during storyboard construction. We find images can aid in accessing rationale and that connections among features aid in deciding what to reuse, creating new artifacts, and constructing. Based on requirements derived from our findings, we present a storyboarding tool, PIC-UP, to facilitate artifact sharing and reuse and evaluate its use in an exploratory study. We conclude with remarks on facilitating reuse and future work.

  17. Discriminative Ocular Artifact Correction for Feature Learning in EEG Analysis.

    Science.gov (United States)

    Li, Xinyang; Guan, Cuntai; Zhang, Haihong; Ang, Kai Keng

    2016-11-16

    Electrooculogram (EOG) artifact contamination is a common critical issue in general electroencephalogram (EEG) studies as well as in brain computer interface (BCI) research. It is especially challenging when dedicated EOG channels are unavailable or when there are very few EEG channels available for ICA-based ocular artifact removal. It is even more challenging to avoid loss of the signal of interest during the artifact correction process, where the signal of interest can be multiple magnitudes weaker than the artifact. To address these issues, we propose a novel discriminative ocular artifact correction approach for feature learning in EEG analysis.Without extra ocular movement measurements, the artifact is extracted from raw EEG data, which is totally automatic and requires no visual inspection of artifacts. Then, artifact correction is optimized jointly with feature extraction by maximizing oscillatory correlations between trials from the same class and minimizing them between trials from different classes. We evaluate this approach on a real world EEG data set comprising 68 subjects performing cognitive tasks. The results showed that the approach is capable of not only suppressing the artifact components but also improving the discriminative power of a classifier with statistical significance. We also demonstrate that the proposed method addresses the confounding issues induced by ocular movements in cognitive EEG study.

  18. Artifact versus arrhythmia in pseudo-polymorphic tachycardia; case report

    Directory of Open Access Journals (Sweden)

    Ahmed V

    2015-04-01

    Full Text Available Vaseem Ahmed, Anish Patel, Abhishek Sharma, Dennis Bloomfield Department of Medicine, Richmond University Medical Center, Staten Island, NY, USA Abstract: We present the case of a young male patient in sinus rhythm whose electrocardiogram (ECG was initially misinterpreted as ventricular tachycardia. Electrocardiographic artifact appearing to be ventricular tachycardia commonly occurs and ECG criteria have been described to aid in the discrimination between artifact and true arrhythmia. There are many causes of artifacts and prompt recognition is important to prevent unnecessary interventions. Keywords: artifact, ventricular tachycardia, pseudo-ventricular tachycardia, notch sign, sinus sign

  19. CT metal artifact reduction by soft inequality constraints

    Science.gov (United States)

    Chukalina, Marina; Nikolaev, Dmitry; Sokolov, Valerii; Ingacheva, Anastasiya; Buzmakov, Alexey; Prun, Victor

    2015-12-01

    The artifacts (known as metal-like artifacts) arising from incorrect reconstruction may obscure or simulate pathology in medical applications, hide or mimic cracks and cavities in the scanned objects in industrial tomographic scans. One of the main reasons caused such artifacts is photon starvation on the rays which go through highly absorbing regions. We indroduce a way to suppress such artifacts in the reconstructions using soft penalty mimicing linear inequalities on the photon starved rays. An efficient algorithm to use such information is provided and the effect of those inequalities on the reconstruction quality is studied.

  20. Medical image of the week: polysomnogram artifact

    Directory of Open Access Journals (Sweden)

    Bartell J

    2015-02-01

    Full Text Available A 54 year-old man with a past medical history of attention deficit hyperactivity disorder (ADHD, low back pain, and paroxysmal supraventricular tachycardia presented to the sleep laboratory for evaluation of sleep disordered breathing. Pertinent medications include fluoxetine, ambien, and clonazepam. His Epworth sleepiness score was 18. He had a total sleep time of 12 min. On the night of his sleep study, the patient was restless and repeatedly changed positions in bed. Figures 1 and 2 show the artifact determined to be lead displacement of O1M2 after the patient shifted in bed, inadvertently removing one of his scalp electrodes. The sine waves are 60 Hz in frequency. Once the problem was identified, the lead was quickly replaced to its proper position.

  1. An extension to artifact-free projection overlaps

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Jianyu, E-mail: jianyulin@hotmail.com [Department of Electrical and Computer Engineering, Curtin University, GPO Box U1987, Perth, Western Australia 6845 (Australia)

    2015-05-15

    Purpose: In multipinhole single photon emission computed tomography, the overlapping of projections has been used to increase sensitivity. Avoiding artifacts in the reconstructed image associated with projection overlaps (multiplexing) is a critical issue. In our previous report, two types of artifact-free projection overlaps, i.e., projection overlaps that do not lead to artifacts in the reconstructed image, were formally defined and proved, and were validated via simulations. In this work, a new proposition is introduced to extend the previously defined type-II artifact-free projection overlaps so that a broader range of artifact-free overlaps is accommodated. One practical purpose of the new extension is to design a baffle window multipinhole system with artifact-free projection overlaps. Methods: First, the extended type-II artifact-free overlap was theoretically defined and proved. The new proposition accommodates the situation where the extended type-II artifact-free projection overlaps can be produced with incorrectly reconstructed portions in the reconstructed image. Next, to validate the theory, the extended-type-II artifact-free overlaps were employed in designing the multiplexing multipinhole spiral orbit imaging systems with a baffle window. Numerical validations were performed via simulations, where the corresponding 1-pinhole nonmultiplexing reconstruction results were used as the benchmark for artifact-free reconstructions. The mean square error (MSE) was the metric used for comparisons of noise-free reconstructed images. Noisy reconstructions were also performed as part of the validations. Results: Simulation results show that for noise-free reconstructions, the MSEs of the reconstructed images of the artifact-free multiplexing systems are very similar to those of the corresponding 1-pinhole systems. No artifacts were observed in the reconstructed images. Therefore, the testing results for artifact-free multiplexing systems designed using the

  2. Prior-based artifact correction (PBAC) in computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Heußer, Thorsten, E-mail: thorsten.heusser@dkfz-heidelberg.de; Brehm, Marcus [Medical Physics in Radiology, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg (Germany); Ritschl, Ludwig [Ziehm Imaging GmbH, Donaustraße 31, 90451 Nürnberg (Germany); Sawall, Stefan; Kachelrieß, Marc [Medical Physics in Radiology, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany and Institute of Medical Physics, Friedrich–Alexander–University (FAU) of Erlangen–Nürnberg, Henkestraße 91, 91052 Erlangen (Germany)

    2014-02-15

    Purpose: Image quality in computed tomography (CT) often suffers from artifacts which may reduce the diagnostic value of the image. In many cases, these artifacts result from missing or corrupt regions in the projection data, e.g., in the case of metal, truncation, and limited angle artifacts. The authors propose a generalized correction method for different kinds of artifacts resulting from missing or corrupt data by making use of available prior knowledge to perform data completion. Methods: The proposed prior-based artifact correction (PBAC) method requires prior knowledge in form of a planning CT of the same patient or in form of a CT scan of a different patient showing the same body region. In both cases, the prior image is registered to the patient image using a deformable transformation. The registered prior is forward projected and data completion of the patient projections is performed using smooth sinogram inpainting. The obtained projection data are used to reconstruct the corrected image. Results: The authors investigate metal and truncation artifacts in patient data sets acquired with a clinical CT and limited angle artifacts in an anthropomorphic head phantom data set acquired with a gantry-based flat detector CT device. In all cases, the corrected images obtained by PBAC are nearly artifact-free. Compared to conventional correction methods, PBAC achieves better artifact suppression while preserving the patient-specific anatomy at the same time. Further, the authors show that prominent anatomical details in the prior image seem to have only minor impact on the correction result. Conclusions: The results show that PBAC has the potential to effectively correct for metal, truncation, and limited angle artifacts if adequate prior data are available. Since the proposed method makes use of a generalized algorithm, PBAC may also be applicable to other artifacts resulting from missing or corrupt data.

  3. Why Critical design is useless

    DEFF Research Database (Denmark)

    Ebbesen, Toke Riis

    practical use, critical design may then become another echo chamber for designers, where they can safely repeat the slogans of design modernism without changing the world. The aim of this presentation will be to return to critical design in the light of the concept of use, and thus to critically examine...

  4. Necessary Smileys and Useless Periods

    DEFF Research Database (Denmark)

    Baron, Naomi; Ling, Richard

    2011-01-01

    . In fact, it is commonly assumed that punctuation on such platforms is either random or absent. This study explores the nature of punctuation (including emoticons) in electronically-mediated communication by analyzing sets of focus group data from adolescents discussing text messaging and by assessing......Communication is increasingly taking place through written messaging using online and mobile platforms such as email, instant messaging and text messaging. A number of scholars have considered whether these texts reflect spoken or written language, though less is known about the role of punctuation...

  5. Kindergarten Children's Perceptions of "Anthropomorphic Artifacts" with Adaptive Behavior

    Science.gov (United States)

    Kuperman, Asi; Mioduser, David

    2012-01-01

    In recent years, children from a kindergarten in central Israel have been exposed to learning experiences in technology as part of the implementation of a curriculum based on technological thinking, including topics related to behaving-adaptive-artifacts (e.g., robots). This study aims to unveil children's stance towards behaving artifacts:…

  6. 78 FR 4878 - Arts and Artifacts Indemnity Panel Advisory Committee

    Science.gov (United States)

    2013-01-23

    ... From the Federal Register Online via the Government Publishing Office NATIONAL FOUNDATION ON THE ARTS AND THE HUMANITIES Arts and Artifacts Indemnity Panel Advisory Committee AGENCY: Federal Council... Artifacts Domestic Indemnity Panel. The purpose of the meeting is for panel review, discussion,...

  7. 76 FR 25378 - Arts and Artifacts Indemnity Panel Advisory; Committee

    Science.gov (United States)

    2011-05-04

    ... From the Federal Register Online via the Government Publishing Office THE NATIONAL FOUNDATION ON THE ARTS AND THE HUMANITIES Federal Council on the Arts and the Humanities Arts and Artifacts...) notice is hereby given that a meeting of the Arts and Artifacts Indemnity Panel of the Federal Council...

  8. Implementing a Smart Method to Eliminate Artifacts of Vital Signals

    Directory of Open Access Journals (Sweden)

    Javadpour A.1

    2015-12-01

    Full Text Available Background: Electroencephalography (EEG has vital and significant applications in different medical fields and is used for the primary evaluation of neurological disorders. Hence, having easy access to suitable and useful signal is very important. Artifacts are undesirable confusions which are generally originated from inevitable human activities such as heartbeat, blinking of eyes and facial muscle activities while receiving EEG signal. It can bring about deformation in these waves though. Objective: The objective of this study was to find a suitable solution to eliminate the artifacts of Vital Signals. Methods: In this study, wavelet transform technique was used. This method is compared with threshold level. The threshold intensity is efficiently crucial because it should not remove the original signal instead of artifacts, and does not hold artifact signal instead of original ones. In this project, we seek to find and implement the algorithm with the ability to automatically remove the artifacts in EEG signals. For this purpose, the use of adaptive filtering methods such as wavelet analysis is appropriate. Finally, we observed that Functional Link Neural Network (FLN performance is better than ANFIS and RBFN to remove such artifacts. Results: We offer an intelligent method for removing artifacts from vital signals in neurological disorders. Conclusion: The proposed method can obtain more accurate results by removing artifacts of vital signals and can be useful in the early diagnosis of neurological and cardiovascular disorders

  9. Teaching and learning the nature of technical artifacts

    NARCIS (Netherlands)

    Frederik, I.; Sonneveld, W.; De Vries, M.J.

    2010-01-01

    Artifacts are probably our most obvious everyday encounter with technology. Therefore, a good understanding of the nature of technical artifacts is a relevant part of technological literacy. In this article we draw from the philosophy of technology to develop a conceptualization of technical artifac

  10. Incidental ferumoxytol artifacts in clinical brain MR imaging

    Energy Technology Data Exchange (ETDEWEB)

    Bowser, Bruce A.; Campeau, Norbert G.; Carr, Carrie M.; Diehn, Felix E.; McDonald, Jennifer S.; Miller, Gary M.; Kaufmann, Timothy J. [Mayo Clinic, Department of Radiology, Rochester, MN (United States)

    2016-11-15

    Ferumoxytol (Feraheme) is a parenteral therapy approved for treatment of iron deficiency anemia. The product insert for ferumoxytol states that it may affect the diagnostic ability of MRI for up to 3 months. However, the expected effects may not be commonly recognized among clinical neuroradiologists. Our purpose is to describe the artifacts we have seen at our institution during routine clinical practice. We reviewed the patients at our institution that had brain MRI performed within 90 days of receiving intravenous ferumoxytol. The imaging was reviewed for specific findings, including diffusion-weighted imaging vascular susceptibility artifact, gradient-echo echo-planar T2*-weighted vascular susceptibility artifact, SWI/SWAN vascular susceptibility artifact, hypointense vascular signal on T2-weighted images, pre-gadolinium contrast vascular enhancement on magnetization-prepared rapid acquisition gradient echo (MPRAGE) imaging, and effects on post-gadolinium contrast T1 imaging. Multiple artifacts were observed in patients having a brain MRI within 3 days of receiving intravenous ferumoxytol. These included susceptibility artifact on DWI, GRE, and SWAN/SWI imaging, pre-gadolinium contrast increased vascular signal on MPRAGE imaging, and decreased expected enhancement on post-gadolinium contrast T1-weighted imaging. Ferumoxytol can create imaging artifacts which complicate clinical interpretation when brain MRI is performed within 3 days of administration. Recognition of the constellation of artifacts produced by ferumoxytol is important in order to obviate additional unnecessary examinations and mitigate errors in interpretation. (orig.)

  11. Naturalistic Experience and the Early Use of Symbolic Artifacts

    Science.gov (United States)

    Troseth, Georgene L.; Casey, Amy M.; Lawver, Kelly A.; Walker, Joan M. T.; Cole, David A.

    2007-01-01

    Experience with a variety of symbolic artifacts has been proposed as a mechanism underlying symbolic development. In this study, the parents of 120 2-year-old children who participated in symbolic object retrieval tasks completed a questionnaire regarding their children's naturalistic experience with symbolic artifacts and activities. In separate…

  12. Magnetic resonance imaging susceptibility artifacts due to metallic foreign bodies.

    Science.gov (United States)

    Hecht, Silke; Adams, William H; Narak, Jill; Thomas, William B

    2011-01-01

    Susceptibility artifacts due to metallic foreign bodies may interfere with interpretation of magnetic resonance (MR) imaging studies. Additionally, migration of metallic objects may pose a risk to patients undergoing MR imaging. Our purpose was to investigate prevalence, underlying cause, and diagnostic implications of susceptibility artifacts in small animal MR imaging and report associated adverse effects. MR imaging studies performed in dogs and cats between April 2008 and March 2010 were evaluated retrospectively for the presence of susceptibility artifacts associated with metallic foreign bodies. Studies were performed using a 1.0 T scanner. Severity of artifacts was graded as 0 (no interference with area of interest), 1 (extension of artifact to area of interest without impairment of diagnostic quality), 2 (impairment of diagnostic quality but diagnosis still possible), or 3 (severe involvement of area of interest resulting in nondiagnostic study). Medical records were evaluated retrospectively to identify adverse effects. Susceptibility artifacts were present in 99/754 (13.1%) of MR imaging studies and were most common in examinations of the brachial plexus, thorax, and cervical spine. Artifacts were caused by identification microchips, ballistic fragments, skin staples/suture material, hemoclips, an ameroid constrictor, and surgical hardware. Three studies were nondiagnostic due to the susceptibility artifact. Adverse effects were not documented.

  13. Metal and calcification artifact reduction for digital breast tomosynthesis

    Science.gov (United States)

    Wicklein, Julia; Jerebko, Anna; Ritschl, Ludwig; Mertelmeier, Thomas

    2017-03-01

    Tomosynthesis images of the breast suffer from artifacts caused by the presence of highly absorbing materials. These can be either induced by metal objects like needles or clips inserted during biopsy devices, or larger calcifications inside the examined breast. Mainly two different kinds of artifacts appear after the filtered backprojection procedure. The first type is undershooting artifacts near edges of high-contrast objects caused by the filtering step. The second type is out-of-plane (ripple) artifacts that appear even in slices where the metal object or macrocalcifications does not exist. Due to the limited angular range of tomosynthesis systems, overlapping structures have high influence on neighboring regions. To overcome these problems, a segmentation of artifact introducing objects is performed on the projection images. Both projection versions, with and without high-contrast objects are filtered independently to avoid undershootings. During backprojection a decision is made for each reconstructed voxel, if it is artifact or high-contrast object. This is based on a mask image, gained from the segmentation of high-contrast objects. This procedure avoids undershooting artifacts and additionally reduces out-of-plane ripple. Results are demonstrated for different kinds of artifact inducing objects and calcifications.

  14. Distributed Cognition and Distributed Morality: Agency, Artifacts and Systems.

    Science.gov (United States)

    Heersmink, Richard

    2017-04-01

    There are various philosophical approaches and theories describing the intimate relation people have to artifacts. In this paper, I explore the relation between two such theories, namely distributed cognition and distributed morality theory. I point out a number of similarities and differences in these views regarding the ontological status they attribute to artifacts and the larger systems they are part of. Having evaluated and compared these views, I continue by focussing on the way cognitive artifacts are used in moral practice. I specifically conceptualise how such artifacts (a) scaffold and extend moral reasoning and decision-making processes, (b) have a certain moral status which is contingent on their cognitive status, and (c) whether responsibility can be attributed to distributed systems. This paper is primarily written for those interested in the intersection of cognitive and moral theory as it relates to artifacts, but also for those independently interested in philosophical debates in extended and distributed cognition and ethics of (cognitive) technology.

  15. Histologic artifacts in abdominal, vaginal, laparoscopic, and robotic hysterectomy specimens: a blinded, retrospective review.

    Science.gov (United States)

    Krizova, Adriana; Clarke, Blaise A; Bernardini, Marcus Q; James, Sarah; Kalloger, Steve E; Boerner, Scott L; Mulligan, Anna Marie

    2011-01-01

    Total laparoscopic hysterectomy (LH) is a minimally invasive technique, which results in comparable morbidity and better cosmesis compared with total abdominal hysterectomy. The literature is discrepant as to whether it is associated with a higher incidence of positive peritoneal cytology compared with total abdominal hysterectomy and recently, associated artifacts, including vascular pseudoinvasion (VPI), have been described. A retrospective histopathologic review of 266 hysterectomy specimens from 2 centers was performed. The observers, blinded to the surgical technique, assessed for the presence of artifactual changes including disruption of the endometrial lining, nuclear crush artifact, VPI, endomyometrial cleft artifact with or without epithelial displacement, inflammatory debris within vessels, serosal carryover, and intratubal contaminants. In addition, the rates of positive peritoneal washings over a 5-year period, and the use of immunohistochemistry (IHC) to aid in cell typing over a 3-year period, were compared between hysterectomies in which a uterine manipulator (UM) device had and had not (nonmanipulated hysterectomies) been used. The hysterectomies were performed for malignant (n=160) and benign (n=102) uterine disease or for ovarian or cervical disease (n=4), and included total abdominal (n=108), vaginal (n=17), laparoscopy-assisted vaginal (n=24), laparoscopy converted to laparotomy (n=10), nonrobotic laparoscopic (n=51), and robot-assisted laparoscopic (n=56) hysterectomies. One hundred and two (38%) of these hysterectomies involved the use of a UM. Artifactual changes of disruption of the endometrial lining, endomyometrial clefts, intratubal contaminants, nuclear crush artifact, intravascular inflammatory debris, and VPI were significantly more common with LH and with the use of a UM, independent of whether the endometrial pathology was benign or malignant. IHC to aid in endometrial cancer subtyping was more likely to be used in manipulated

  16. Body MR Imaging: Artifacts, k-Space, and Solutions.

    Science.gov (United States)

    Huang, Susie Y; Seethamraju, Ravi T; Patel, Pritesh; Hahn, Peter F; Kirsch, John E; Guimaraes, Alexander R

    2015-01-01

    Body magnetic resonance (MR) imaging is challenging because of the complex interaction of multiple factors, including motion arising from respiration and bowel peristalsis, susceptibility effects secondary to bowel gas, and the need to cover a large field of view. The combination of these factors makes body MR imaging more prone to artifacts, compared with imaging of other anatomic regions. Understanding the basic MR physics underlying artifacts is crucial to recognizing the trade-offs involved in mitigating artifacts and improving image quality. Artifacts can be classified into three main groups: (a) artifacts related to magnetic field imperfections, including the static magnetic field, the radiofrequency (RF) field, and gradient fields; (b) artifacts related to motion; and (c) artifacts arising from methods used to sample the MR signal. Static magnetic field homogeneity is essential for many MR techniques, such as fat saturation and balanced steady-state free precession. Susceptibility effects become more pronounced at higher field strengths and can be ameliorated by using spin-echo sequences when possible, increasing the receiver bandwidth, and aligning the phase-encoding gradient with the strongest susceptibility gradients, among other strategies. Nonuniformities in the RF transmit field, including dielectric effects, can be minimized by applying dielectric pads or imaging at lower field strength. Motion artifacts can be overcome through respiratory synchronization, alternative k-space sampling schemes, and parallel imaging. Aliasing and truncation artifacts derive from limitations in digital sampling of the MR signal and can be rectified by adjusting the sampling parameters. Understanding the causes of artifacts and their possible solutions will enable practitioners of body MR imaging to meet the challenges of novel pulse sequence design, parallel imaging, and increasing field strength.

  17. [Joint correction for motion artifacts and off-resonance artifacts in multi-shot diffusion magnetic resonance imaging].

    Science.gov (United States)

    Wu, Wenchuan; Fang, Sheng; Guo, Hua

    2014-06-01

    Aiming at motion artifacts and off-resonance artifacts in multi-shot diffusion magnetic resonance imaging (MRI), we proposed a joint correction method in this paper to correct the two kinds of artifacts simultaneously without additional acquisition of navigation data and field map. We utilized the proposed method using multi-shot variable density spiral sequence to acquire MRI data and used auto-focusing technique for image deblurring. We also used direct method or iterative method to correct motion induced phase errors in the process of deblurring. In vivo MRI experiments demonstrated that the proposed method could effectively suppress motion artifacts and off-resonance artifacts and achieve images with fine structures. In addition, the scan time was not increased in applying the proposed method.

  18. Colorectal Cancer "Methylator Phenotype": Fact or Artifact?

    Directory of Open Access Journals (Sweden)

    Charles Anacleto

    2005-04-01

    Full Text Available It has been proposed that human colorectal tumors can be classified into two groups: one in which methylation is rare, and another with methylation of several loci associated with a "CpG island methylated phenotype (CIMP," characterized by preferential proximal location in the colon, but otherwise poorly defined. There is considerable overlap between this putative methylator phenotype and the well-known mutator phenotype associated with microsatellite instability (MSI. We have examined hypermethylation of the promoter region of five genes (DAPK, MGMT, hMLH1, p16INK4a, and p14ARF in 106 primary colorectal cancers. A graph depicting the frequency of methylated loci in the series of tumors showed a continuous, monotonically decreasing distribution quite different from the previously claimed discontinuity. We observed a significant association between the presence of three or more methylated loci and the proximal location of the tumors. However, if we remove from analysis the tumors with hMLH1 methylation or those with MSI, the significance vanishes, suggesting that the association between multiple methylations and proximal location was indirect due to the correlation with MSI. Thus, our data do not support the independent existence of the so-called methylator phenotype and suggest that it rather may represent a statistical artifact caused by confounding of associations.

  19. Searching for alien artifacts on the moon

    Science.gov (United States)

    Davies, P. C. W.; Wagner, R. V.

    2013-08-01

    The Search for Extraterrestrial Intelligence (SETI) has a low probability of success, but it would have a high impact if successful. Therefore it makes sense to widen the search as much as possible within the confines of the modest budget and limited resources currently available. To date, SETI has been dominated by the paradigm of seeking deliberately beamed radio messages. However, indirect evidence for extraterrestrial intelligence could come from any incontrovertible signatures of non-human technology. Existing searchable databases from astronomy, biology, earth and planetary sciences all offer low-cost opportunities to seek a footprint of extraterrestrial technology. In this paper we take as a case study one particular new and rapidly-expanding database: the photographic mapping of the Moon's surface by the Lunar Reconnaissance Orbiter (LRO) to 0.5 m resolution. Although there is only a tiny probability that alien technology would have left traces on the moon in the form of an artifact or surface modification of lunar features, this location has the virtue of being close, and of preserving traces for an immense duration. Systematic scrutiny of the LRO photographic images is being routinely conducted anyway for planetary science purposes, and this program could readily be expanded and outsourced at little extra cost to accommodate SETI goals, after the fashion of the SETI@home and Galaxy Zoo projects.

  20. Method for eliminating artifacts in CCD imagers

    Science.gov (United States)

    Turko, B. T.; Yates, G. J.

    1990-06-01

    An electronic method for eliminating artifacts in a video camera employing a charge coupled device (CCD) as an image sensor is presented. The method comprises the step of initializing the camera prior to normal readout. The method includes a first dump cycle period for transferring radiation generated charge into the horizontal register. This occurs while the decaying image on the phosphor being imaged is being integrated in the photosites, and a second dump cycle period, occurring after the phosphor image has decayed, for rapidly dumping unwanted smear charge which has been generated in the vertical registers. Image charge is then transferred from the photosites and to the vertical registers and readout in conventional fashion. The inventive method allows the video camera to be used in environments having high ionizing radiation content, and to capture images of events of very short duration and occurring either within or outside the normal visual wavelength spectrum. Resultant images are free from ghost, smear, and smear phenomena caused by insufficient opacity of the registers, and are also free from random damage caused by ionization charges which exceed the charge limit capacity of the photosites.

  1. The specific contribution of object's origin on artifacts categorization

    Institute of Scientific and Technical Information of China (English)

    SUN Yuhao; WANG Zhe; FU Xiaolan

    2006-01-01

    Gelman and Bloom found that adults and children's object naming was sensitive to how an object was created (man-made or not), but they did not reveal on which specific level of conceptual system this effect was. Using a free-naming task and a force-choice task, two experiments were conducted to test a hypothesis that this effect was specifically on domain level ("artifact/non-artifact" distinction). In Experiment 1, participants were asked to name shortly-depicted objects, rate their confidence, and report their reasons for each naming response. Results showed that most of the naming responses in "man-made" condition were in artifact domain, and most in "natural" condition were in non-artifact domain, although in both conditions names were very divergent on basic level. In Experiment 2, another group of participants were asked to choose one from two names (one in artifact domain and the other in non-artifact domain) to match the same shortly-depicted objects presented in the first experiment. Results of Experiment 1 on domain level were replicated in Experiment 2. These convergent findings supported the hypothesis that the effect of object's origin is specifically on domain level of conceptual system of objects. Reasons explicitly reported for naming responses in Experiment 1 suggested that participants might automatically infer objects' functions in "man-made" condition but not in "natural" condition.Here the function-based hypothesis of artifacts classification is discussed.

  2. An observer model for quantifying panning artifacts in digital pathology

    Science.gov (United States)

    Avanaki, Ali R. N.; Espig, Kathryn S.; Xthona, Albert; Lanciault, Christian; Kimpe, Tom R. L.

    2017-03-01

    Typically, pathologists pan from one region of a slide to another, choosing areas of interest for closer inspection. Due to finite frame rate and imperfect zero-order hold reconstruction (i.e., the non-zero time to reach the target brightness after a change in pixel drive), panning in whole slide images (WSI) cause visual artifacts. It is important to study the impact of such artifacts since research suggests that 49% of navigation is conducted in low-power/overview with digital pathology (Molin et al., Histopathology 2015). In this paper, we explain what types of medical information may be harmed by panning artifacts, propose a method to simulate panning artifacts, and design an observer model to predict the impact of panning artifacts on typical human observers' performance in basic diagnostically relevant visual tasks. The proposed observer model is based on derivation of perceived object border maps from luminance and chrominance information and may be tuned to account for visual acuity of the human observer to be modeled. Our results suggest that increasing the contrast (e.g., using a wide gamut display) with a slow response panel may not mitigate the panning artifacts which mostly affect visual tasks involving spatial discrimination of objects (e.g., normal vs abnormal structure, cell type and spatial relationships between them, and low-power nuclear morphology), and that the panning artifacts worsen with increasing panning speed. The proposed methods may be used as building blocks in an automatic WSI quality assessment framework.

  3. Towards discrimination of infarcts from artifacts in DWI scans

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Varsha; Prakash, K.N.B.; Nowinski, Wieslaw L. [Technology and Research, Biomedical Imaging Lab, Agency for Science, Singapore (Singapore)

    2008-04-15

    Accurate and rapid quantification of infarcts from DWI scans is critical in acute ischemic stroke. Acquisition artifacts lead to hyperintense regions in DWI MR scans resulting in false positives. Discriminating infarcts and artifacts helps in reducing infarct segmentation errors. An algorithm based on two-dimensional symmetry of artifacts about the midsagittal plane and three-dimensional spatial coherence of infarct regions is proposed to characterize and separate infarcts from artifacts. The two dimensional symmetry is quantified by propagating Poisson errors in the intensity space of each pixel, and distant and spatially incoherent regions in a volume are considered as artifacts. The combination of two criteria enhances the confidence in the decision whether a hyperintense region is an infarct or artifact. The validity of the proposed algorithm is demonstrated using 51 cases. The improvement in results is demonstrated in three situations: (1) automatic infarct slice identification resulting in an average increase in (specificity, Dice Statistical Index (DSI)) by (15.2%, 6.9%) while the sensitivity decrease is by only 1.5% and (2) automatic infarct segmentation using two different algorithms: first resulting in an average DSI increase by 7.6% and second by 5.1%. On a matlab platform, the processing time is < 1 s. The proposed algorithm is useful as a fast post-processing tool to reduce artifacts in infarct processing applications. (orig.)

  4. Adiabatic Low-Pass J Filters for Artifact Suppression in Heteronuclear NMR

    DEFF Research Database (Denmark)

    Meier, Sebastian; Benie, Andrew J; Duus, Jens Øllgaard

    2009-01-01

    NMR artifact purging: Modern NMR experiments depend on efficient coherence transfer pathways for their sensitivity and on suppression of undesired pathways leading to artifacts for their spectral clarity. A novel robust adiabatic element suppresses hard-to-get-at artifacts.......NMR artifact purging: Modern NMR experiments depend on efficient coherence transfer pathways for their sensitivity and on suppression of undesired pathways leading to artifacts for their spectral clarity. A novel robust adiabatic element suppresses hard-to-get-at artifacts....

  5. A POCS-Based Algorithm for Blocking Artifacts Reduction

    Institute of Scientific and Technical Information of China (English)

    ZHAO Yi-hong; CHENG Guo-hua; YU Song-yu

    2006-01-01

    An algorithm for blocking artifacts reduction in DCT domain for block-based image coding was developed. The algorithm is based on the projection onto convex set (POCS) theory. Due to the fact that the DCT characteristics of shifted blocks are different caused by the blocking artifacts, a novel smoothness constraint set and the corresponding projection operator were proposed to reduce the blocking artifacts by discarding the undesired high frequency coefficients in the shifted DCT blocks. The experimental results show that the proposed algorithm outperforms the conventional algorithms in terms of objective quality, subjective quality, and convergence property.

  6. Artifacts interfering with interpretation of cone beam computed tomography images.

    Science.gov (United States)

    Makins, Scott R

    2014-07-01

    Artifacts in radiographic imaging are discrepancies between the reconstructed visual image and the content of the subject. In radiographic imaging, this means the grayscale values in the image do not accurately reflect the attenuation values of the subject. Structures may also appear that do not exist in the subject. Whatever the source or appearance of image artifacts, their presence degrades the accuracy of the image in relation to the true characteristics of the subject. One should therefore be aware of the presence of artifacts and be familiar with their characteristic appearances in order to enhance the extraction of diagnostic information.

  7. Towards a concept of community artifact ecology in HCI?

    DEFF Research Database (Denmark)

    Saad-Sulonen, Joanna; Korsgaard, Henrik

    or workplaces do. This has implications on understanding how to research and design HCI for communities but also on refining the ecological perspective in HCI. We look in particular at examples from preliminary research on a local self-organised urban community and discuss what existing concepts in the ecology......In this paper we introduce the concept of community artifact ecology. We argue that taking a community perspective on the concept of artifact ecologies is relevant in HCI because communities are also dealing with multitudes of artifacts, in ways di↵erent that individuals, organizations...... literature are relevant to consider and how they change with the community perspective....

  8. Comparative Evaluation of Adaptive Filter and Neuro-Fuzzy Filter in Artifacts Removal From Electroencephalogram Signal

    Directory of Open Access Journals (Sweden)

    Paulchamy Balaiah

    2012-01-01

    Full Text Available Problem statement: This study presents an effective method for removing mixed artifacts (EOG-Electro-ocular gram, ECG-Electrocardiogram, EMG-Electromyogram from the EEG-Electroencephalogram records. The noise sources increases the difficulty in analyzing the EEG and obtaining clinical information. EEG signals are multidimensional, non-stationary (i.e., statistical properties are not invariant in time, time domain biological signals, which are not reproducible. It is supposed to contain information about what is going on in the ensemble of excitatory pyramidal neuron level, at millisecond temporal resolution scale. Since scalp EEG contains considerable amount of noise and artifacts and exactly where it is coming from is poorly determined, extracting information from it is extremely challenging. For this reason it is necessary to design specific filters to decrease such artifacts in EEG records. Approach: Some of the other methods that are really appealing are artifact removal through Independent Component Analysis (ICA, Wavelet Transforms, Linear filtering and Artificial Neural Networks. ICA method could be used in situations, where large numbers of noises need to be distinguished, but it is not suitable for on-line real time application like Brain Computer Interface (BCI. Wavelet transforms are suitable for real-time application, but there all success lies in the selection of the threshold function. Linear filtering is best when; the frequency of noises does not interfere or overlap with each other. In this study we proposed adaptive filtering and neuro-fuzzy filtering method to remove artifacts from EEG. Adaptive filter performs linear filtering. Neuro-fuzzy approaches are very promising for non-linear filtering of noisy image. The multiple-output structure is based on recursive processing. It is able to adapt the filtering action to different kinds of corrupting noise. Fuzzy reasoning embedded into the network structure aims at reducing errors

  9. Artifact Diamond Its Allure And Significance

    Science.gov (United States)

    Yoder, Max N.

    1989-01-01

    While the preponderance of the mechanical, optical, and electronic properties of natural diamond have been known for over a decade, only recently has artifact diamond in technologically useful form factors become an exciting possibility. The advent of sacrificial, lattice matched crystalline substrates provides the basis not only for semiconducting applications of diamond, but for optical mirrors, lenses, and windows as well. As a semiconductor, diamond has the highest resistivity, the highest saturated electron velocity, the highest thermal conductivity, the lowest dielectric constant, the highest dielectric strength, the greatest hardness, the largest bandgap and the smallest lattice constant of any material. It also has electron and hole mobilities greater than those of silicon. Its figure of merit as a microwave power amplifier is unexcelled and exceeds that of silicon by a multiplier of 8200. For integrated circuit potential, its thermal conductivity, saturated velocity, and dielectric constant also place it in the premier position (32 times that of silicon, 46 times that of GaAs). Although not verified, its radiation hardness should also be unmatched. Aside from its brilliant sparkle as a gemstone, there has been little use of diamond in the field of optics. Processing of the diamond surface now appears to be as simple as that of any other material --albeit with different techniques. In fact, it may be possible to etch diamond far more controllably (at economically viable rates) than any other material as the product of the etch is gaseous and the etched trough is self-cleaning. Other properties of diamond make it an ideal optical material. Among them are its unmatched thermal conductivity, its extremely low absorption loss above 228 nanometers, and unmatched Young's modulus, Poisson's ratio, tensile strength, hardness, thermal shock, and modulus of elasticity. If the recently-found mechanisms by which erbium impurities in III-V junctions can be made to "lase

  10. How Do Artifact Models Help Direct SPI Projects?

    DEFF Research Database (Denmark)

    Kuhrmann, Marco; Richardson, Ita

    2015-01-01

    To overcome shortcomings associated with software process improvement (SPI), we previously recommended that process engineers focus on the artifacts to be developed in SPI projects. These artifacts should define desired outcomes, rather than specific methods. During this prior research, we...... developed a model for Artifact-based Software Process Improvement & Management (ArSPI). We are now carrying out studies to confirm our claims that ArSPI will provide benefits such as quality assurance. In this paper, we report on an experimental setting in which we developed and analyzed a strategy to use...... artifact models to direct process model improvement. We analyzed a process specification, the realized model, and the generated electronic process guide. We used ArSPI v0.9 as our process model and the Capability Maturity Model Integration (CMMI) as an external reference to provide a set of overall...

  11. Cultural Artifact Detection in Long Wave Infrared Imagery.

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Dylan Zachary [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Craven, Julia M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Ramon, Eric [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-01-01

    Detection of cultural artifacts from airborne remotely sensed data is an important task in the context of on-site inspections. Airborne artifact detection can reduce the size of the search area the ground based inspection team must visit, thereby improving the efficiency of the inspection process. This report details two algorithms for detection of cultural artifacts in aerial long wave infrared imagery. The first algorithm creates an explicit model for cultural artifacts, and finds data that fits the model. The second algorithm creates a model of the background and finds data that does not fit the model. Both algorithms are applied to orthomosaic imagery generated as part of the MSFE13 data collection campaign under the spectral technology evaluation project.

  12. Information Content Across Types of Nurse Cognitive Artifacts.

    Science.gov (United States)

    Blaz, Jacquelyn W; Doig, Alexa K; Cloyes, Kristin G; Staggers, Nancy

    2016-01-01

    Acute care nurses commonly use personalized cognitive artifacts to organize information during a shift. The purpose of this content analysis is to compare information content across three formats of cognitive artifacts used by acute care nurses in a medical oncology unit: hand-made free-form, preprinted skeleton, and EHR-generated. Information contained in free-form and skeleton artifacts is more tailored to specific patient context than the NSR. Free-form and skeleton artifacts provide a space for synthesizing information to construct a "story of the patient" that is missing in the NSR. Future design of standardized handoff tools will need to take these differences into account for successful adoption by acute care nurses, including tailoring of information by patient, not just unit type, and allowing a space for nurses to construct a narrative describing the patients "story."

  13. THE DISABLED AND ART: SELECTED ARTIFACTS OF GHANAIAN ...

    African Journals Online (AJOL)

    made into the artifacts of six (6) selected disabled artists in Ashanti Region. Description of ten ... 2010 Kwame Nkrumah University of Science and Technology (KNUST). Journal of Science and .... pation and women empowerment. There is no.

  14. Automatic correction of dental artifacts in PET/MRI

    DEFF Research Database (Denmark)

    Ladefoged, Claes N.; Andersen, Flemming L.; Keller, Sune;

    2015-01-01

    A challenge when using current magnetic resonance (MR)-based attenuation correction in positron emission tomography/MR imaging (PET/MRI) is that the MRIs can have a signal void around the dental fillings that is segmented as artificial air-regions in the attenuation map. For artifacts connected...... to the background, we propose an extension to an existing active contour algorithm to delineate the outer contour using the non-attenuation corrected PET image and the original attenuation map. We propose a combination of two different methods for differentiating the artifacts within the body from the anatomical...... air-regions by first using a template of artifact regions, and second, representing the artifact regions with a combination of active shape models and k-nearest-neighbors. The accuracy of the combined method has been evaluated using 25 18 F-fluorodeoxyglucose PET/MR patients. Results showed...

  15. Automatic correction of dental artifacts in PET/MRI

    DEFF Research Database (Denmark)

    Ladefoged, Claes N.; Andersen, Flemming L.; Keller, Sune

    2015-01-01

    A challenge when using current magnetic resonance (MR)-based attenuation correction in positron emission tomography/MR imaging (PET/MRI) is that the MRIs can have a signal void around the dental fillings that is segmented as artificial air-regions in the attenuation map. For artifacts connected...... to the background, we propose an extension to an existing active contour algorithm to delineate the outer contour using the non-attenuation corrected PET image and the original attenuation map. We propose a combination of two different methods for differentiating the artifacts within the body from the anatomical...... air-regions by first using a template of artifact regions, and second, representing the artifact regions with a combination of active shape models and k-nearest-neighbors. The accuracy of the combined method has been evaluated using 25 18 F-fluorodeoxyglucose PET/MR patients. Results showed...

  16. Metal artifact reduction based on the combined prior image

    CERN Document Server

    Zhang, Yanbo

    2014-01-01

    Metallic implants introduce severe artifacts in CT images, which degrades the image quality. It is an effective method to reduce metal artifacts by replacing the metal affected projection with the forward projection of a prior image. How to find a good prior image is the key of this class methods, and numerous algorithms have been proposed to address this issue recently. In this work, by using image mutual correlation, pixels in the original reconstructed image or linear interpolation corrected image, which are less affected by artifacts, are selected to build a combined image. Thereafter, a better prior image is generated from the combined image by using tissue classification. The results of three patients' CT images show that the proposed method can reduce metal artifacts remarkably.

  17. Avoiding Stair-Step Artifacts in Image Registration for GOES-R Navigation and Registration Assessment

    Science.gov (United States)

    Grycewicz, Thomas J.; Tan, Bin; Isaacson, Peter J.; De Luccia, Frank J.; Dellomo, John

    2016-01-01

    In developing software for independent verification and validation (IVV) of the Image Navigation and Registration (INR) capability for the Geostationary Operational Environmental Satellite R Series (GOES-R) Advanced Baseline Imager (ABI), we have encountered an image registration artifact which limits the accuracy of image offset estimation at the subpixel scale using image correlation. Where the two images to be registered have the same pixel size, subpixel image registration preferentially selects registration values where the image pixel boundaries are close to lined up. Because of the shape of a curve plotting input displacement to estimated offset, we call this a stair-step artifact. When one image is at a higher resolution than the other, the stair-step artifact is minimized by correlating at the higher resolution. For validating ABI image navigation, GOES-R images are correlated with Landsat-based ground truth maps. To create the ground truth map, the Landsat image is first transformed to the perspective seen from the GOES-R satellite, and then is scaled to an appropriate pixel size. Minimizing processing time motivates choosing the map pixels to be the same size as the GOES-R pixels. At this pixel size image processing of the shift estimate is efficient, but the stair-step artifact is present. If the map pixel is very small, stair-step is not a problem, but image correlation is computation-intensive. This paper describes simulation-based selection of the scale for truth maps for registering GOES-R ABI images.

  18. TRUNCATION ARTIFACT IN MAGNETIC RESONANCE IMAGES OF THE CANINE SPINAL CORD.

    Science.gov (United States)

    Gregori, Tommaso; Lam, Richard; Priestnall, Simon L; Lamb, Christopher R

    2016-11-01

    The truncation artifact in magnetic resonance (MR) images is a line of abnormal signal intensity that occurs parallel to an interface between tissues of markedly different signal intensity. In order to demonstrate the truncation artifact in sagittal images of the canine spinal cord and the effect of changing spatial resolution, we conducted an experimental in vitro study. A section of fixed canine spinal cord was imaged using a 1.5T magnet. Spatial resolution was increased by increasing the acquisition matrix and reconstruction matrix, producing series of T2-weighted (T2w) images with the following pixel sizes: A, 1.6 (vertical) × 2.2 mm(2) (horizontal); B, 1.2 × 1.7 mm(2) ; C, 0.8 × 1.1 mm(2) ; D, 0.4 × 0. 6 mm(2) . Plots of mean pixel value across the cord showed variations in signal intensity compatible with truncation artifact, which appeared as a single, wide central hyperintense zone in low-resolution images and as multiple narrower zones in high spatial resolution images. Even in images obtained using the highest spatial resolution available for the MR system, the edge of the spinal cord was not accurately defined and the central canal was not visible. The experiment was repeated using an unfixed spinal cord specimen with focal compression applied to mimic a pathologic lesion. Slight hyperintensity was observed within the spinal cord at the site of compression although the cord was normal histologically. Results of this study suggest that caution should be applied when interpreting hyperintensity affecting the spinal cord in T2w sagittal images of clinical patients because of the possibility that the abnormal signal could represent a truncation artifact.

  19. A new interpretation of distortion artifacts in sweep measurements

    DEFF Research Database (Denmark)

    Torras Rosell, Antoni; Jacobsen, Finn

    2011-01-01

    The characterization of acoustical spaces by means of impulse response measurements is often biased by the nonlinear behavior of the loudspeaker used to excite the system under test. In this context the distortion immunity provided by the sweep technique has been investigated. The results show th...... that the sweep method can reject a significant amount of distortion artifacts but, in contrast to what is claimed in the literature, it cannot exclude all distortion artifacts from the causal part of the estimated impulse response....

  20. Sonographic twinkling artifact for renal calculus detection: correlation with CT.

    Science.gov (United States)

    Dillman, Jonathan R; Kappil, Mariam; Weadock, William J; Rubin, Jonathan M; Platt, Joel F; DiPietro, Michael A; Bude, Ronald O

    2011-06-01

    To retrospectively correlate sonographic color Doppler twinkling artifact within the kidneys with unenhanced computed tomography (CT) in the detection of nephrolithiasis. Institutional review board approval was obtained for this retrospective HIPAA-complaint investigation, and the informed consent requirement was waived. Sonographic imaging reports describing the presence of renal twinkling artifact between January 2008 and September 2009 were identified. Subjects who did not undergo unenhanced abdominal CT within 2 weeks after sonography were excluded. Ultrasound examinations were reviewed by three radiologists working together, and presence, number, location, and size of renal twinkling artifacts were documented by consensus opinion. Sonographic findings were correlated with unenhanced CT (5-mm section width, no overlap) for nephrolithiasis and other causes of twinkling artifact. The number, location, and size of renal calculi at CT were documented. The presence of sonographic renal twinkling artifact, in general, had a 78% (95% confidence interval: 0.66, 0.90) positive predictive value for nephrolithiasis anywhere in the kidneys at CT. The true-positive rate of twinkling artifact for confirmed calculi at CT was 49% (73 of 148 twinkling foci), while the false-positive rate was 51% (75 of 148 twinkling foci). The overall sensitivity of twinkling artifact for the detection of specific individual renal calculi observed at CT was 55% (95% confidence interval: 0.47, 0.64). While renal twinkling artifact is commonly associated with nephrolithiasis, this finding is relatively insensitive in routine clinical practice and has a high false-positive rate when 5-mm unenhanced CT images are used as the reference standard. http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.11102128/-/DC1. RSNA, 2011

  1. Mitigation of artifacts in rtm with migration kernel decomposition

    KAUST Repository

    Zhan, Ge

    2012-01-01

    The migration kernel for reverse-time migration (RTM) can be decomposed into four component kernels using Born scattering and migration theory. Each component kernel has a unique physical interpretation and can be interpreted differently. In this paper, we present a generalized diffraction-stack migration approach for reducing RTM artifacts via decomposition of migration kernel. The decomposition leads to an improved understanding of migration artifacts and, therefore, presents us with opportunities for improving the quality of RTM images.

  2. Reduction of metal artifacts: beam hardening and photon starvation effects

    Science.gov (United States)

    Yadava, Girijesh K.; Pal, Debashish; Hsieh, Jiang

    2014-03-01

    The presence of metal-artifacts in CT imaging can obscure relevant anatomy and interfere with disease diagnosis. The cause and occurrence of metal-artifacts are primarily due to beam hardening, scatter, partial volume and photon starvation; however, the contribution to the artifacts from each of them depends on the type of hardware. A comparison of CT images obtained with different metallic hardware in various applications, along with acquisition and reconstruction parameters, helps understand methods for reducing or overcoming such artifacts. In this work, a metal beam hardening correction (BHC) and a projection-completion based metal artifact reduction (MAR) algorithms were developed, and applied on phantom and clinical CT scans with various metallic implants. Stainless-steel and Titanium were used to model and correct for metal beam hardening effect. In the MAR algorithm, the corrupted projection samples are replaced by the combination of original projections and in-painted data obtained by forward projecting a prior image. The data included spine fixation screws, hip-implants, dental-filling, and body extremity fixations, covering range of clinically used metal implants. Comparison of BHC and MAR on different metallic implants was used to characterize dominant source of the artifacts, and conceivable methods to overcome those. Results of the study indicate that beam hardening could be a dominant source of artifact in many spine and extremity fixations, whereas dental and hip implants could be dominant source of photon starvation. The BHC algorithm could significantly improve image quality in CT scans with metallic screws, whereas MAR algorithm could alleviate artifacts in hip-implants and dentalfillings.

  3. Situating Creative Artifacts in Art and Design Research

    Directory of Open Access Journals (Sweden)

    Nithikul Nimkulrat

    2013-09-01

    Full Text Available This article aims to discuss the position of art and design artifacts, and their creation, in a practice-led research process.  Two creative productions and exhibitions featuring my textile artifacts were intentionally carried out in order to tackle a specific research problem, and these will be examined here as case studies.  These cases cover the production and exhibition of two sets of artworks, named Seeing Paper and Paper World, that were created as part of my completed doctoral research entitled Paperness: Expressive Material inTextile Art from an Artist’s Viewpoint. The study examined the relationship between a physical material and artistic expression in textile art and design.  Both cases exemplify the roles of creative productions and artifacts situated in the process of inquiry.  Throughout a practice-led research process, art and design artifacts can serve as inputs into knowledge production and as outputs for knowledge communication.  As inputs, both art productions and artifacts can be the starting point of a research project from which the research question is formulated.  They can also provide data for analysis from which knowledge is constructed.  Asoutputs, artifacts can indicate whether the research problem requires reformulation, demonstrate the experiential knowledge of the creative process, and strengthen the findings articulated in the written output.  Creative practice in a research context can contribute to generating or enhancing the knowledge which is embedded in the practice and embodied by the practitioner.  This knowledge or insight can be obtained from the artist creating the artifact, the artifact created, the process of making it, and the culture in which it is produced and viewed or used, all taking place at different stages of a research process.

  4. A methodology for validating artifact removal techniques for physiological signals.

    Science.gov (United States)

    Sweeney, Kevin T; Ayaz, Hasan; Ward, Tomás E; Izzetoglu, Meltem; McLoone, Seán F; Onaral, Banu

    2012-09-01

    Artifact removal from physiological signals is an essential component of the biosignal processing pipeline. The need for powerful and robust methods for this process has become particularly acute as healthcare technology deployment undergoes transition from the current hospital-centric setting toward a wearable and ubiquitous monitoring environment. Currently, determining the relative efficacy and performance of the multiple artifact removal techniques available on real world data can be problematic, due to incomplete information on the uncorrupted desired signal. The majority of techniques are presently evaluated using simulated data, and therefore, the quality of the conclusions is contingent on the fidelity of the model used. Consequently, in the biomedical signal processing community, there is considerable focus on the generation and validation of appropriate signal models for use in artifact suppression. Most approaches rely on mathematical models which capture suitable approximations to the signal dynamics or underlying physiology and, therefore, introduce some uncertainty to subsequent predictions of algorithm performance. This paper describes a more empirical approach to the modeling of the desired signal that we demonstrate for functional brain monitoring tasks which allows for the procurement of a "ground truth" signal which is highly correlated to a true desired signal that has been contaminated with artifacts. The availability of this "ground truth," together with the corrupted signal, can then aid in determining the efficacy of selected artifact removal techniques. A number of commonly implemented artifact removal techniques were evaluated using the described methodology to validate the proposed novel test platform.

  5. A hybrid intelligence approach to artifact recognition in digital publishing

    Science.gov (United States)

    Vega-Riveros, J. Fernando; Santos Villalobos, Hector J.

    2006-02-01

    The system presented integrates rule-based and case-based reasoning for artifact recognition in Digital Publishing. In Variable Data Printing (VDP) human proofing could result prohibitive since a job could contain millions of different instances that may contain two types of artifacts: 1) evident defects, like a text overflow or overlapping 2) style-dependent artifacts, subtle defects that show as inconsistencies with regard to the original job design. We designed a Knowledge-Based Artifact Recognition tool for document segmentation, layout understanding, artifact detection, and document design quality assessment. Document evaluation is constrained by reference to one instance of the VDP job proofed by a human expert against the remaining instances. Fundamental rules of document design are used in the rule-based component for document segmentation and layout understanding. Ambiguities in the design principles not covered by the rule-based system are analyzed by case-based reasoning, using the Nearest Neighbor Algorithm, where features from previous jobs are used to detect artifacts and inconsistencies within the document layout. We used a subset of XSL-FO and assembled a set of 44 document samples. The system detected all the job layout changes, while obtaining an overall average accuracy of 84.56%, with the highest accuracy of 92.82%, for overlapping and the lowest, 66.7%, for the lack-of-white-space.

  6. Artifact reduction in HARP strain maps using anisotropic smoothing

    Science.gov (United States)

    Abd-Elmoniem, Khaled Z.; Parthasarathy, Vijay; Prince, Jerry L.

    2006-03-01

    Harmonic phase (HARP) MRI is used to measure myocardial motion and strain from tagged MR images. HARP MRI uses limited number of samples from the spectrum of the tagged images to reconstruct motion and strain. The HARP strain maps, however, suffer from artifacts that limit the accuracy of the computations and degrade the appearance of the strain maps. Causes of these, so called 'zebra', artifacts include image noise, Gibbs ringing, and interference from other Fourier spectral peaks. Computing derivatives of the HARP phase, which are needed to estimate strain, further accentuates these artifacts. Previous methods to reduce these artifacts include 1-D and 2-D nonlinear filtering of the HARP derivatives, and a 2-D linear filtering of unwrapped HARP phase. A common drawback among these methods is the lack of proper segmentation of the myocardium from the blood pool. Because of the lack of segmentation, the noisy phase values from the blood pool enter into the computation in the smoothed strain maps, which causes artifacts. In this work, we propose a smoothing method based on anisotropic diffusion that filters the HARP derivatives strictly within the myocardium without the need for prior segmentation. The information about tissue geometry and the strain distribution is used to restrict the smoothing to within the myocardium, thereby ensuring minimum distortion of the final strain map. Preliminary results demonstrate the ability of anisotropic diffusion for better artifact reduction and lesser strain distortion than the existing methods.

  7. Artifact-Based Transformation of IBM Global Financing

    Science.gov (United States)

    Chao, Tian; Cohn, David; Flatgard, Adrian; Hahn, Sandy; Linehan, Mark; Nandi, Prabir; Nigam, Anil; Pinel, Florian; Vergo, John; Wu, Frederick Y.

    IBM Global Financing (IGF) is transforming its business using the Business Artifact Method, an innovative business process modeling technique that identifies key business artifacts and traces their life cycles as they are processed by the business. IGF is a complex, global business operation with many business design challenges. The Business Artifact Method is a fundamental shift in how to conceptualize, design and implement business operations. The Business Artifact Method was extended to solve the problem of designing a global standard for a complex, end-to-end process while supporting local geographic variations. Prior to employing the Business Artifact method, process decomposition, Lean and Six Sigma methods were each employed on different parts of the financing operation. Although they provided critical input to the final operational model, they proved insufficient for designing a complete, integrated, standard operation. The artifact method resulted in a business operations model that was at the right level of granularity for the problem at hand. A fully functional rapid prototype was created early in the engagement, which facilitated an improved understanding of the redesigned operations model. The resulting business operations model is being used as the basis for all aspects of business transformation in IBM Global Financing.

  8. Inference and coherence in causal-based artifact categorization.

    Science.gov (United States)

    Puebla, Guillermo; Chaigneau, Sergio E

    2014-01-01

    In four experiments, we tested conditions under which artifact concepts support inference and coherence in causal categorization. In all four experiments, participants categorized scenarios in which we systematically varied information about artifacts' associated design history, physical structure, user intention, user action and functional outcome, and where each property could be specified as intact, compromised or not observed. Consistently across experiments, when participants received complete information (i.e., when all properties were observed), they categorized based on individual properties and did not show evidence of using coherence to categorize. In contrast, when the state of some property was not observed, participants gave evidence of using available information to infer the state of the unobserved property, which increased the value of the available information for categorization. Our data offers answers to longstanding questions regarding artifact categorization, such as whether there are underlying causal models for artifacts, which properties are part of them, whether design history is an artifact's causal essence, and whether physical appearance or functional outcome is the most central artifact property.

  9. Detection of eye blink artifacts from single prefrontal channel electroencephalogram.

    Science.gov (United States)

    Chang, Won-Du; Cha, Ho-Seung; Kim, Kiwoong; Im, Chang-Hwan

    2016-02-01

    Eye blinks are one of the most influential artifact sources in electroencephalogram (EEG) recorded from frontal channels, and thereby detecting and rejecting eye blink artifacts is regarded as an essential procedure for improving the quality of EEG data. In this paper, a novel method to detect eye blink artifacts from a single-channel frontal EEG signal was proposed by combining digital filters with a rule-based decision system, and its performance was validated using an EEG dataset recorded from 24 healthy participants. The proposed method has two main advantages over the conventional methods. First, it uses single-channel EEG data without the need for electrooculogram references. Therefore, this method could be particularly useful in brain-computer interface applications using headband-type wearable EEG devices with a few frontal EEG channels. Second, this method could estimate the ranges of eye blink artifacts accurately. Our experimental results demonstrated that the artifact range estimated using our method was more accurate than that from the conventional methods, and thus, the overall accuracy of detecting epochs contaminated by eye blink artifacts was markedly increased as compared to conventional methods. The MATLAB package of our library source codes and sample data, named Eyeblink Master, is open for free download.

  10. A simple method to reduce aliasing artifacts in color flow mode imaging

    DEFF Research Database (Denmark)

    Udesen, Jesper; Nikolov, Svetoslav; Jensen, Jørgen Arendt

    2005-01-01

    It is a well known limitation in conventional blood velocity estimation using a phase estimation approach, that aliasing artifacts are present, when the blood velocities exceed a value determined by half the pulse repetition frequency (the Nyquist frequency). This paper proposes a simple anti......-aliasing discriminator (AAD) method based on using two different pulse repetition frequencies to increase the aliasing limit to twice the Nyquist frequency. The method is evaluated in simulations using the Field II program. The axial velocity in a virtual blood vessel is found along one axial line, where N=10 emissions...

  11. Metal-related artifacts in instrumented spine. Techniques for reducing artifacts in CT and MRI: state of the art

    OpenAIRE

    Stradiotti, P.; Curti, A.; G. Castellazzi; Zerbi, A.

    2009-01-01

    The projectional nature of radiogram limits its amount of information about the instrumented spine. MRI and CT imaging can be more helpful, using cross-sectional view. However, the presence of metal-related artifacts at both conventional CT and MRI imaging can obscure relevant anatomy and disease. We reviewed the literature about overcoming artifacts from metallic orthopaedic implants at high-field strength MRI imaging and multi-detector CT. The evolution of multichannel CT has made available...

  12. Metal-related artifacts in instrumented spine. Techniques for reducing artifacts in CT and MRI: state of the art.

    Science.gov (United States)

    Stradiotti, P; Curti, A; Castellazzi, G; Zerbi, A

    2009-06-01

    The projectional nature of radiogram limits its amount of information about the instrumented spine. MRI and CT imaging can be more helpful, using cross-sectional view. However, the presence of metal-related artifacts at both conventional CT and MRI imaging can obscure relevant anatomy and disease. We reviewed the literature about overcoming artifacts from metallic orthopaedic implants at high-field strength MRI imaging and multi-detector CT. The evolution of multichannel CT has made available new techniques that can help minimizing the severe beam-hardening artifacts. The presence of artifacts at CT from metal hardware is related to image reconstruction algorithm (filter), tube current (in mA), X-ray kilovolt peak, pitch, hardware composition, geometry (shape), and location. MRI imaging has been used safely in patients with orthopaedic metallic implants because most of these implants do not have ferromagnetic properties and have been fixed into position. However, on MRI imaging metallic implants may produce geometric distortion, the so-called susceptibility artifact. In conclusion, although 140 kV and high milliamperage second exposures are recommended for imaging patients with hardware, caution should always be exercised, particularly in children, young adults, and patients undergoing multiple examinations. MRI artifacts can be minimized by positioning optimally and correctly the examined anatomy part with metallic implants in the magnet and by choosing fast spin-echo sequences, and in some cases also STIR sequences, with an anterior to posterior frequency-encoding direction and the smallest voxel size.

  13. Removing speech artifacts from electroencephalographic recordings during overt picture naming.

    Science.gov (United States)

    Porcaro, Camillo; Medaglia, Maria Teresa; Krott, Andrea

    2015-01-15

    A number of electroencephalography (EEG) studies have investigated the time course of brain activation during overt word production. The interpretation of their results is complicated by the fact that articulatory movements may mask the cognitive components of interest. The first aim of the present study was to investigate when speech artifacts occur during word production planning and what effects they have on the spatio-temporal neural activation pattern. The second aim was to propose a new method that strongly attenuates speech artifacts during overt picture naming and to compare it with existing methods. EEG and surface electromyograms (EMGs) of the lips were recorded while participants overtly named pictures in a picture-word interference paradigm. The comparison of the raw data with lip EMG and the comparison of source localizations of raw and corrected EEG data showed that speech artifacts occurred mainly from ~400 ms post-stimulus onset, but some earlier artifacts mean that they occur much earlier than hitherto assumed. We compared previously used methods of speech artifacts removal (SAR) with a new method, which is based on Independent Component Analysis (SAR-ICA). Our new method clearly outperformed other methods. In contrast to other methods, there was only a weak correlation between the lip EMG and the corrected data by SAR-ICA. Also, only the data corrected with our method showed activation of cerebral sources consistent with meta-analyses of word production.

  14. Artifact detection in electrodermal activity using sparse recovery

    Science.gov (United States)

    Kelsey, Malia; Palumbo, Richard Vincent; Urbaneja, Alberto; Akcakaya, Murat; Huang, Jeannie; Kleckner, Ian R.; Barrett, Lisa Feldman; Quigley, Karen S.; Sejdic, Ervin; Goodwin, Matthew S.

    2017-05-01

    Electrodermal Activity (EDA) - a peripheral index of sympathetic nervous system activity - is a primary measure used in psychophysiology. EDA is widely accepted as an indicator of physiological arousal, and it has been shown to reveal when psychologically novel events occur. Traditionally, EDA data is collected in controlled laboratory experiments. However, recent developments in wireless biosensing have led to an increase in out-of-lab studies. This transition to ambulatory data collection has introduced challenges. In particular, artifacts such as wearer motion, changes in temperature, and electrical interference can be misidentified as true EDA responses. The inability to distinguish artifact from signal hinders analyses of ambulatory EDA data. Though manual procedures for identifying and removing EDA artifacts exist, they are time consuming - which is problematic for the types of longitudinal data sets represented in modern ambulatory studies. This manuscript presents a novel technique to automatically identify and remove artifacts in EDA data using curve fitting and sparse recovery methods. Our method was evaluated using labeled data to determine the accuracy of artifact identification. Procedures, results, conclusions, and future directions are presented.

  15. Metal artifact reduction method using metal streaks image subtraction

    Energy Technology Data Exchange (ETDEWEB)

    Pua, Rizza D.; Cho, Seung Ryong [Dept. of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

    2014-04-15

    Many studies have been dedicated for metal artifact reduction (MAR); however, the methods are successful to varying degrees depending on situations. Sinogram in-painting, filtering, iterative method are some of the major categories of MAR. Each has its own merits and weaknesses. A combination of these methods or hybrid methods have also been developed to make use of the different benefits of two techniques and minimize the unfavorable results. Our method focuses on the in-paitning approach and a hybrid MAR described by Xia et al. Although in-painting scheme is an effective technique in reducing the primary metal artifacts, a major drawback is the reintroduction of new artifacts that can be caused by an inaccurate interpolation process. Furthermore, combining the segmented metal image to the corrected nonmetal image in the final step of a conventional inpainting approach causes an issue of incorrect metal pixel values. Our proposed method begins with a sinogram in-painting approach and ends with an image-based metal artifact reduction scheme. This work provides a simple, yet effective solution for reducing metal artifacts and acquiring the original metal pixel information. The proposed method demonstrated its effectiveness in a simulation setting. The proposed method showed image quality that is comparable to the standard MAR; however, quantitatively more accurate than the standard MAR.

  16. Motion Artifact in the MR imaging of temporomandibular disorders

    Energy Technology Data Exchange (ETDEWEB)

    Tamamura, Kiyoharu; Miyajima, Hisashi; Nihei, Yoshinobu; Nemoto, Ryuichi; Ohno, Tomoya [Ohu Univ., Koriyama, Fukushima (Japan). School of Dentistry

    1997-09-01

    Recently, magnetic resonance imaging (MRI) is indispensable for the diagnosis of temporomandibular disorders (TMD). Motion Artifacts of MRI occur more frequently than in other conventional methods, because it takes a long time to obtain the images. This paper reported on Motion Artifacts on MRI. MRI studies of 232 temporomandibular joints were performed in 116 patients with TMD by using a 0.5-T magnetic resonance (MR) scanner, with spin echo sequence: protondensity-weighted. And we took MRI slices at opening phase and closing phase. So 232 slices were gathered and we evaluated clinically the incidence of Motion Artifacts, that is to say, double and multiple images and other factors. The 103 slices in 56 patients showed Motion Artifacts. There is no significant difference between sexes. By age group, those in their teens were most frequent, followed by those in their fifties, forties, thirties and twenties. Also the same results were obtained for double image and multiple image. Incidence of Motion Artifact was most frequent at the opening phase. There is no significant difference between double and multiple image. (author)

  17. Artifacts by dental materials on magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Hyun Sook; Choi, Deuk Lin; Kim, Ki Jung [Soonchunhyang University Hospital, Asan (Korea, Republic of); Suh, Won Hyuck [Korea University Hospital, Seoul (Korea, Republic of)

    1992-05-15

    Magnetic resonance imaging (MRI) has proved to be a valuable method for evaluation of the head and neck. Unfortunately, metallic devices associated with certain dental fillings and appliances often cause variable artifacts that can obscure normal or pathologic conditions on MR and computed tomography. In this work, we assessed the MR appearance of dental prosthetic materials in vitro and in vivo including precious alloys, nonprecions alloys, resin, amalgam and titanium alloy. For in vivo studies, these materials were placed in healthy volunteer's mouths and then images were assessed. Analysis of the appearance of shape and extent of artifact, and observed influence of these artifacts on the image interpretation at 0.2 Tesla permanent type MR scanner were valuated. Material used as temporary or permanent filling of crowns such as amalgam, precious alloy and, microfilled resin did not cause artifact on the image. The size of the artifact produced by the nonprecious alloys was influenced by the ferromagnetism of the object and the volume prosthesis, and was related to the scanning sequence. Nonprecious alloys produced minimal local signal distortion, where precious alloys, and dental resin had no effect on the MR images in vivo. These results were mainly from a low field strength MR scanner used in this study.

  18. Metal artifact reduction in CT via ray profile correction

    Science.gov (United States)

    Ha, Sungsoo; Mueller, Klaus

    2016-03-01

    In computed tomography (CT), metal implants increase the inconsistencies between the measured data and the linear assumption made by the analytical CT reconstruction algorithm. The inconsistencies appear in the form of dark and bright bands and streaks in the reconstructed image, collectively called metal artifacts. The standard method for metal artifact reduction (MAR) replaces the inconsistent data with the interpolated data. However, sinogram interpolation not only introduces new artifacts but it also suffers from the loss of detail near the implanted metals. With the help of a prior image that is usually estimated from the metal artifact-degraded image via computer vision techniques, improvements are feasible but still no MAR method exists that is widely accepted and utilized. We propose a technique that utilizes a prior image from a CT scan taken of the patient before implanting the metal objects. Hence there is a sufficient amount of structural similarity to cover the loss of detail around the metal implants. Using the prior scan and a segmentation or model of the metal implant our method then replaces sinogram interpolation with ray profile matching and estimation which yields much more reliable data estimates for the affected sinogram regions. As preliminary work, we built a new MAR framework on fan-beam geometry and tested it to remove simulated metal artifacts on a thorax phantom. The comparison with two representative sinogram correction based MAR methods shows very promising results.

  19. Image Degradation in Microscopic Images: Avoidance, Artifacts, and Solutions.

    Science.gov (United States)

    Roels, Joris; Aelterman, Jan; De Vylder, Jonas; Lippens, Saskia; Luong, Hiêp Q; Guérin, Christopher J; Philips, Wilfried

    2016-01-01

    The goal of modern microscopy is to acquire high-quality image based data sets. A typical microscopy workflow is set up in order to address a specific biological question and involves different steps. The first step is to precisely define the biological question, in order to properly come to an experimental design for sample preparation and image acquisition. A better object representation allows biological users to draw more reliable scientific conclusions. Image restoration can manipulate the acquired data in an effort to reduce the impact of artifacts (spurious results) due to physical and technical limitations, resulting in a better representation of the object of interest. However, precise usage of these algorithms is necessary so as to avoid further artifacts that might influence the data analysis and bias the conclusions. It is essential to understand image acquisition, and how it introduces artifacts and degradations in the acquired data, so that their effects on subsequent analysis can be minimized. This paper provides an overview of the fundamental artifacts and degradations that affect many micrographs. We describe why artifacts appear, in what sense they impact overall image quality, and how to mitigate them by first improving the acquisition parameters and then applying proper image restoration techniques.

  20. Dental artifacts in the head and neck region

    DEFF Research Database (Denmark)

    Ladefoged, Claes N; Hansen, Adam E; Keller, Sune H;

    2015-01-01

    substituted with soft tissue information. Our inpainting algorithm delineates the outer contour of signal voids breaching the anatomical volume using the non-attenuation-corrected PET image and classifies the inner air regions based on an aligned template of likely dental artifact areas. The reconstructed PET...... images were evaluated visually and quantitatively using regions of interests in reference regions. The volume of the artifacts and the computed relative differences in mean and max standardized uptake value (SUV) between the two PET images are reported. RESULTS: The MR-based volume of the susceptibility......% (± 11%), respectively, in the corrected region. SUV underestimation decreased with the distance to the signal void and correlated with the volume of the susceptibility artifact on the MR-AC attenuation map. CONCLUSIONS: Metallic dental work may cause severe MR signal voids. The resulting PET...

  1. Correction of ring artifacts in X-ray tomographic images

    DEFF Research Database (Denmark)

    Lyckegaard, Allan; Johnson, G.; Tafforeau, P.

    2011-01-01

    Ring artifacts are systematic intensity distortions located on concentric circles in reconstructed tomographic X-ray images. When using X-ray tomography to study for instance low-contrast grain boundaries in metals it is crucial to correct for the ring artifacts in the images as they may have...... the same intensity level as the grain boundaries and thus make it impossible to perform grain segmentation. This paper describes an implementation of a method for correcting the ring artifacts in tomographic X-ray images of simple objects such as metal samples where the object and the background...... are separable. The method is implemented in Matlab, it works with very little user interaction and may run in parallel on a cluster if applied to a whole stack of images. The strength and robustness of the method implemented will be demonstrated on three tomographic X-ray data sets: a mono-phase β...

  2. Medical image of the week: DBS polysomnogram artifact

    Directory of Open Access Journals (Sweden)

    Shetty S,

    2015-10-01

    Full Text Available A 79-year-old man with known Parkinson’s disease and status post deep brain stimulator (DBS implantation underwent an overnight polysomnogram for clinical suspicion of obstructive sleep apnea. Artifact was seen on the polysomnogram recording (Figures 1 & 2. Patient-related electrical artifacts may be seen from devices such as pacemakers, deep brain stimulators and vagal nerve simulators. Abrupt discontinuation of DBS is associated with a high likelihood of worsening of symptoms in patients with Parkinson’s disease (1. Patients with DBS are most commonly programmed in monopolar mode. Bipolar configuration, forms a short electrical dipole that affects a relatively smaller volume of tissue and generates far less artifact, suggesting that this may be an effective option in a Parkinsonian patient with indications for polysomnography (2.

  3. A patient-specific scatter artifacts correction method

    CERN Document Server

    Zhao, Wei; Niu, Kai; Schafer, Sebastian; Royalty, Kevin; Chen, Guang-Hong

    2015-01-01

    This paper provides a fast and patient-specific scatter artifact correction method for cone-beam computed tomography (CBCT) used in image-guided interventional procedures. Due to increased irradiated volume of interest in CBCT imaging, scatter radiation has increased dramatically compared to 2D imaging, leading to a degradation of image quality. In this study, we propose a scatter artifact correction strategy using an analytical convolution-based model whose free parameters are estimated using a rough estimation of scatter profiles from the acquired cone-beam projections. It was evaluated using Monte Carlo simulations with both monochromatic and polychromatic X-ray sources. The results demonstrated that the proposed method significantly reduced the scatter-induced shading artifacts and recovered CT numbers.

  4. Dental artifacts in the head and neck region:

    DEFF Research Database (Denmark)

    Ladefoged, Claes N.; Hansen, Adam E.; Keller, Sune

    2015-01-01

    substituted with soft tissue information. Our inpainting algorithm delineates the outer contour of signal voids breaching the anatomical volume using the non-attenuation-corrected PET image and classifies the inner air regions based on an aligned template of likely dental artifact areas. The reconstructed PET...... images were evaluated visually and quantitatively using regions of interests in reference regions. The volume of the artifacts and the computed relative differences in mean and max standardized uptake value (SUV) between the two PET images are reported. RESULTS: The MR-based volume of the susceptibility......% (± 11%), respectively, in the corrected region. SUV underestimation decreased with the distance to the signal void and correlated with the volume of the susceptibility artifact on the MR-AC attenuation map. CONCLUSIONS: Metallic dental work may cause severe MR signal voids. The resulting PET...

  5. EEG artifact removal—state-of-the-art and guidelines

    Science.gov (United States)

    Urigüen, Jose Antonio; Garcia-Zapirain, Begoña

    2015-06-01

    This paper presents an extensive review on the artifact removal algorithms used to remove the main sources of interference encountered in the electroencephalogram (EEG), specifically ocular, muscular and cardiac artifacts. We first introduce background knowledge on the characteristics of EEG activity, of the artifacts and of the EEG measurement model. Then, we present algorithms commonly employed in the literature and describe their key features. Lastly, principally on the basis of the results provided by various researchers, but also supported by our own experience, we compare the state-of-the-art methods in terms of reported performance, and provide guidelines on how to choose a suitable artifact removal algorithm for a given scenario. With this review we have concluded that, without prior knowledge of the recorded EEG signal or the contaminants, the safest approach is to correct the measured EEG using independent component analysis—to be precise, an algorithm based on second-order statistics such as second-order blind identification (SOBI). Other effective alternatives include extended information maximization (InfoMax) and an adaptive mixture of independent component analyzers (AMICA), based on higher order statistics. All of these algorithms have proved particularly effective with simulations and, more importantly, with data collected in controlled recording conditions. Moreover, whenever prior knowledge is available, then a constrained form of the chosen method should be used in order to incorporate such additional information. Finally, since which algorithm is the best performing is highly dependent on the type of the EEG signal, the artifacts and the signal to contaminant ratio, we believe that the optimal method for removing artifacts from the EEG consists in combining more than one algorithm to correct the signal using multiple processing stages, even though this is an option largely unexplored by researchers in the area.

  6. Ring artifacts correction in compressed sensing tomographic reconstruction

    CERN Document Server

    Paleo, Pierre

    2015-01-01

    We present a novel approach to handle ring artifacts correction in compressed sensing tomographic reconstruction. The correction is part of the reconstruction process, which differs from classical sinogram pre-processing and image post-processing techniques. The principle of compressed sensing tomographic reconstruction is presented. Then, we show that the ring artifacts correction can be integrated in the reconstruction problem formalism. We provide numerical results for both simulated and real data. This technique is included in the PyHST2 code which is used at the European Synchrotron Radiation Facility for tomographic reconstruction.

  7. Resources, co-evolution and artifacts theory in CSCW

    CERN Document Server

    Ackerman, Mark S; Erickson, Thomas; Kellogg, Wendy A

    2007-01-01

    A topic of significant interest to the CSCW, IT and IS communities is the issue of how software and other technical systems come to be adopted and used. We know from considerable research that people use systems in many ways, and that the process of incorporating them in their everyday activities can require a great deal of effort. One way of understanding adoption and use is by considering artifacts as resources in people's environments. ""Resources, Co-Evolution and Artifacts: Theory in CSCW"" looks at how resources get created, adopted, modified, and die, by using a number of theoretical an

  8. Inter-deriving Semantic Artifacts for Object-Oriented Programming

    DEFF Research Database (Denmark)

    Danvy, Olivier; Johannsen, Jacob

    2008-01-01

    We present a new abstract machine for Abadi and Cardelli's untyped calculus of objects. What is special about this semantic artifact (i.e., man-made construct) is that is mechanically corresponds to both the reduction semantics (i.e., small-step operational semantics) and the natural semantics (i...... actual substitutions, we then represent object methods as closures and in the same inter-derivational spirit, we present three new semantic artifacts: a reduction semantics for a version of Abadi and Cardelli's untyped calculus of objects with explicit substitutions, an environment-based abstract machine...

  9. EEG Artifact Removal Using a Wavelet Neural Network

    Science.gov (United States)

    Nguyen, Hoang-Anh T.; Musson, John; Li, Jiang; McKenzie, Frederick; Zhang, Guangfan; Xu, Roger; Richey, Carl; Schnell, Tom

    2011-01-01

    !n this paper we developed a wavelet neural network. (WNN) algorithm for Electroencephalogram (EEG) artifact removal without electrooculographic (EOG) recordings. The algorithm combines the universal approximation characteristics of neural network and the time/frequency property of wavelet. We. compared the WNN algorithm with .the ICA technique ,and a wavelet thresholding method, which was realized by using the Stein's unbiased risk estimate (SURE) with an adaptive gradient-based optimal threshold. Experimental results on a driving test data set show that WNN can remove EEG artifacts effectively without diminishing useful EEG information even for very noisy data.

  10. Towards the Paperless Office : Ecology of artifacts at work

    OpenAIRE

    2011-01-01

    Stepping one step closer to the paperless office by looking into existing technologies. Looking at the whole ecology of digital artifacts of users. Only by understanding how people use paper, how they relate to their digital ecology of artifacts, and what makes them adopt new products can we hope to get one step closer to the paperless office. There has been an extreme growth in mobile devices the last couple of year, and there have been a couple of new platforms emerging in the mobil...

  11. Elimination of artifacts in interline charge-coupled device imagers.

    Science.gov (United States)

    Turko, B. T.; Yates, G. J.

    1991-10-01

    Charge-coupled devices (CCDs) of interline transfer design are especially useful in imaging at high frame rates. However, their sensitivity to ionization radiation and the reduced effective opacity for vertical charge transfer registers cause undesired image artifacts. Random white spots from the radiation and "ghost" images (or smear) generated in the registers may severely impair the image quality. An electronic method of eliminating these artificats is described. Special sequences of pulses clock the CCD, quickly dumping the unwanted charge. The fast readout of images, cleared of artifacts, follows immediately.

  12. Metal artifacts in computed tomography for radiation therapy planning: dosimetric effects and impact of metal artifact reduction

    Science.gov (United States)

    Giantsoudi, Drosoula; De Man, Bruno; Verburg, Joost; Trofimov, Alexei; Jin, Yannan; Wang, Ge; Gjesteby, Lars; Paganetti, Harald

    2017-04-01

    A significant and increasing number of patients receiving radiation therapy present with metal objects close to, or even within, the treatment area, resulting in artifacts in computed tomography (CT) imaging, which is the most commonly used imaging method for treatment planning in radiation therapy. In the presence of metal implants, such as dental fillings in treatment of head-and-neck tumors, spinal stabilization implants in spinal or paraspinal treatment or hip replacements in prostate cancer treatments, the extreme photon absorption by the metal object leads to prominent image artifacts. Although current CT scanners include a series of correction steps for beam hardening, scattered radiation and noisy measurements, when metal implants exist within or close to the treatment area, these corrections do not suffice. CT metal artifacts affect negatively the treatment planning of radiation therapy either by causing difficulties to delineate the target volume or by reducing the dose calculation accuracy. Various metal artifact reduction (MAR) methods have been explored in terms of improvement of organ delineation and dose calculation in radiation therapy treatment planning, depending on the type of radiation treatment and location of the metal implant and treatment site. Including a brief description of the available CT MAR methods that have been applied in radiation therapy, this article attempts to provide a comprehensive review on the dosimetric effect of the presence of CT metal artifacts in treatment planning, as reported in the literature, and the potential improvement suggested by different MAR approaches. The impact of artifacts on the treatment planning and delivery accuracy is discussed in the context of different modalities, such as photon external beam, brachytherapy and particle therapy, as well as by type and location of metal implants.

  13. Communication in the Digital City and Artifact Lives

    Science.gov (United States)

    Kryssanov, Victor V.; Okabe, Masayuki; Kakusho, Koh; Minoh, Michihiko

    This paper proposes a theoretical basis for the design and analysis of distributed information systems. A quantitative criterion is defined to estimate the efficiency of computer-mediated communication, and to monitor artifact lives as well. The theoretical concepts are discussed in a context of an example related to car use and servicing.

  14. Artifacts as Stories: Understanding Families, Digital Literacies, and Storied Lives

    Science.gov (United States)

    Lewis Ellison, Tisha

    2016-01-01

    This column focuses on the interactions during family and group conversation circles that not only helped participants talk about personal, emotional, and social issues in their digital stories but also helped them make sense of artifacts and the meanings that stories carry in shared spaces and practices. This work adds to the bourgeoning…

  15. Tracing the Paths of Moving Artifacts in Youth Media Production

    Science.gov (United States)

    Gibbons, Damiana

    2010-01-01

    Using a theoretical grounding in social semiotics, chronotopes, and social spaces with youth, I will discuss how identities are made possible and expressed in the interplay between the different parts of the youth video production process as youth artifacts as they move through time and space. The majority of my data is what I have come to term…

  16. Science Teachers Sharing Artifacts from Practice like Students’ Tablet Productions

    DEFF Research Database (Denmark)

    Nielsen, Birgitte Lund

    2013-01-01

    to support the success of integrating technology. Experiences from a large-scale, long-term TPD project for primary and secondary science teachers supporting the teachers in trying out innovative practices and new ICT tools in own classes, and in sharing artifacts from these trials in teacher networks...

  17. Determination of the temperature artifact during ultrasound hyperthermia.

    Science.gov (United States)

    Waterman, F M

    1990-01-01

    Temperature artifacts produced by very small uncoated thermocouples during ultrasonic heating are evaluated by backward extrapolation of the linear portion of the temperature rise curve or by backward extrapolation of the exponential portion of the temperature decay curve. The accuracy of these techniques for larger clinically used thermocouples is investigated by use of a two-dimensional model of the bioheat equation which simulates the transfer of heat radially from a probe 1 mm in diameter. The accuracy of these techniques is found to depend upon the perfusion rate. In the absence of perfusion, both extrapolation techniques underestimate the artifact by nearly 40%. Extrapolation of the temperature rise curve is very sensitive to the perfusion rate and this technique results in errors exceeding 100% when the perfusion rate is high. Extrapolation of the temperature decay curve produces more consistent results. Over a blood flow range of 0-100 ml/100 g per min, the artifact is underestimated by an amount that varies from approximately 40% to 30% respectively. Thus, the artifact can be determined to within 5% by this technique by increasing the extrapolated value by 35%.

  18. Classification of independent components of EEG into multiple artifact classes

    DEFF Research Database (Denmark)

    Frølich, Laura; Andersen, Tobias; Mørup, Morten

    2015-01-01

    In this study, we aim to automatically identify multiple artifact types in EEG. We used multinomial regression to classify independent components of EEG data, selecting from 65 spatial, spectral, and temporal features of independent components using forward selection. The classifier identified...

  19. Ballistocardiogram artifacts in simultaneous EEG-fMRI acquisitions

    NARCIS (Netherlands)

    Vanderperren, K.; Ramautar, J.R.; Novitskiy, N.; de Vos, M.; Mennes, M.; Vanrumste, B.; Stiers, P.; van den Bergh, B.; Wagemans, J.; Lagae, L.; Sunaert, S.; Van Huffel, S.

    2007-01-01

    Vanderperren, K., Ramautar, J., Novitskiy, N., De Vos, M., Mennes, M., Vanrumste, B., Stiers, P., Van den Bergh, B., Wagemans, J., Lagae, L., Sunaert, S., Van Huffel, S. (2007). Ballistocardiogram artifacts in simultaneous EEG-fMRI acquisitions. International Journal of Bioelectromagnetism, 9 (3), 1

  20. 77 FR 40914 - Arts and Artifacts Indemnity Panel Advisory Committee

    Science.gov (United States)

    2012-07-11

    ... ARTS AND THE HUMANITIES Arts and Artifacts Indemnity Panel Advisory Committee AGENCY: Federal Council on the Arts and the Humanities, National Endowment for the Humanities, National Foundation on the Arts and the Humanities. ACTION: Notice of meeting. SUMMARY: Pursuant to section 10(a)(2) of...

  1. 77 FR 64146 - Arts and Artifacts Indemnity Panel Advisory Committee

    Science.gov (United States)

    2012-10-18

    ... ARTS AND THE HUMANITIES Arts and Artifacts Indemnity Panel Advisory Committee AGENCY: Federal Council on the Arts and the Humanities, National Endowment for the Humanities. ACTION: Notice of meeting... hereby given that the Federal Council on the Arts and the Humanities will hold a meeting of the Arts...

  2. Artifact suppression and analysis of brain activities with electroencephalography signals

    Institute of Scientific and Technical Information of China (English)

    Md. Rashed-Al-Mahfuz; Md. Rabiul Islam; Keikichi Hirose; Md. Khademul Islam Molla

    2013-01-01

    Brain-computer interface is a communication system that connects the brain with computer (or other devices) but is not dependent on the normal output of the brain (i.e., peripheral nerve and muscle). Electro-oculogram is a dominant artifact which has a significant negative influence on further analysis of real electroencephalography data. This paper presented a data adaptive technique for artifact suppression and brain wave extraction from electroencephalography signals to detect regional brain activities. Empirical mode decomposition based adaptive thresholding approach was employed here to suppress the electro-oculogram artifact. Fractional Gaussian noise was used to determine the threshold level derived from the analysis data without any training. The purified electroencephalography signal was composed of the brain waves also called rhythmic components which represent the brain activities. The rhythmic components were extracted from each electroencephalography channel using adaptive wiener filter with the original scale. The regional brain activities were mapped on the basis of the spatial distribution of rhythmic components, and the results showed that different regions of the brain are activated in response to different stimuli. This research analyzed the activities of a single rhythmic component, alpha with respect to different motor imaginations. The experimental results showed that the proposed method is very efficient in artifact suppression and identifying individual motor imagery based on the activities of alpha component.

  3. Design of educational artifacts as support to learning process.

    Science.gov (United States)

    Resende, Adson Eduardo; Vasconcelos, Flávio Henrique

    2012-01-01

    The aim of this paper is to identify utilization schemes developed by students and teachers in their interaction with educational workstations in the electronic measurement and instrumentation laboratory at the Department of Electrical Engineering in the Federal University of Minas Gerais (UFMG), Brazil. After that, these schemes were used to design a new workstation. For this, it was important to bear in mind that the mentioned artifacts contain two key characteristics: (1) one from the designers themselves, resulting from their experience and their technical knowledge of what they are designing and (2) the experience from users and the means through which they take advantage of and develop these artifacts, in turn rendering them appropriate to perform the proposed task - the utilization schemes developed in the process of mediation between the user and the artifact. The satisfactory fusion of these two points makes these artifacts a functional unit - the instruments. This research aims to demonstrate that identifying the utilization schemes by taking advantage of user experience and incorporating this within the design, facilitates its appropriation and, consequently, its efficiency as an instrument of learning.

  4. Is the New Item Priority Effect an Experimental Artifact?

    Science.gov (United States)

    Andre, Thomas

    This research was directed at determining whether the new item priority (NIP) effect in free recall was a result of an experimental artifact produced by the joint action of the serial position effect and the randomization of items over trials, or a consequence of a strategy of recalling newer items before older ones. In the experiment, subjects…

  5. Artifacts as Stories: Understanding Families, Digital Literacies, and Storied Lives

    Science.gov (United States)

    Lewis Ellison, Tisha

    2016-01-01

    This column focuses on the interactions during family and group conversation circles that not only helped participants talk about personal, emotional, and social issues in their digital stories but also helped them make sense of artifacts and the meanings that stories carry in shared spaces and practices. This work adds to the bourgeoning…

  6. Investigating 3d Reconstruction Methods for Small Artifacts

    Science.gov (United States)

    Evgenikou, V.; Georgopoulos, A.

    2015-02-01

    Small artifacts have always been a real challenge when it comes to 3D modelling. They usually present severe difficulties for their 3D reconstruction. Lately, the demand for the production of 3D models of small artifacts, especially in the cultural heritage domain, has dramatically increased. As with many cases, there are no specifications and standards for this task. This paper investigates the efficiency of several mainly low cost methods for 3D model production of such small artifacts. Moreover, the material, the color and the surface complexity of these objects id also investigated. Both image based and laser scanning methods have been considered as alternative data acquisition methods. The evaluation has been confined to the 3D meshes, as texture depends on the imaging properties, which are not investigated in this project. The resulting meshes have been compared to each other for their completeness, and accuracy. It is hoped that the outcomes of this investigation will be useful to researchers who are planning to embark into mass production of 3D models of small artifacts.

  7. INVESTIGATING 3D RECONSTRUCTION METHODS FOR SMALL ARTIFACTS

    Directory of Open Access Journals (Sweden)

    V. Evgenikou

    2015-02-01

    Full Text Available Small artifacts have always been a real challenge when it comes to 3D modelling. They usually present severe difficulties for their 3D reconstruction. Lately, the demand for the production of 3D models of small artifacts, especially in the cultural heritage domain, has dramatically increased. As with many cases, there are no specifications and standards for this task. This paper investigates the efficiency of several mainly low cost methods for 3D model production of such small artifacts. Moreover, the material, the color and the surface complexity of these objects id also investigated. Both image based and laser scanning methods have been considered as alternative data acquisition methods. The evaluation has been confined to the 3D meshes, as texture depends on the imaging properties, which are not investigated in this project. The resulting meshes have been compared to each other for their completeness, and accuracy. It is hoped that the outcomes of this investigation will be useful to researchers who are planning to embark into mass production of 3D models of small artifacts.

  8. Soft tissue artifact in canine kinematic gait analysis

    NARCIS (Netherlands)

    Schwencke, M.; Smolders, L.A.; Bergknut, N.; Gustas, P.; Meij, B.P.; Hazewinkel, H.A.W.

    2012-01-01

    Vet Surg. 2012 Oct;41(7):829-37. doi: 10.1111/j.1532-950X.2012.01021.x. Soft tissue artifact in canine kinematic gait analysis. Schwencke M, Smolders LA, Bergknut N, Gustås P, Meij BP, Hazewinkel HA. Source Department of Clinical Sciences of Companion Animals,, Faculty of Veterinary Medicine, Utrech

  9. Negligible motion artifacts in scalp electroencephalography (EEG during treadmill walking

    Directory of Open Access Journals (Sweden)

    Kevin eNathan

    2016-01-01

    Full Text Available Recent Mobile Brain/Body Imaging (MoBI techniques based on active electrode scalp electroencephalogram (EEG allow the acquisition and real-time analysis of brain dynamics during active unrestrained motor behavior involving whole body movements such as treadmill walking, over-ground walking and other locomotive and non-locomotive tasks. Unfortunately, MoBI protocols are prone to physiological and non-physiological artifacts, including motion artifacts that may contaminate the EEG recordings. A few attempts have been made to quantify these artifacts during locomotion tasks but with inconclusive results due in part to methodological pitfalls. In this paper, we investigate the potential contributions of motion artifacts in scalp EEG during treadmill walking at three different speeds (1.5, 3.0, and 4.5 km/h using a wireless 64 channel active EEG system and a wireless inertial sensor attached to the subject’s head. The experimental setup was designed according to good measurement practices using state-of-the-art commercially-available instruments, and the measurements were analyzed using Fourier analysis and wavelet coherence approaches. Contrary to prior claims, the subjects’ motion did not significantly affect their EEG during treadmill walking although precaution should be taken when gait speeds approach 4.5 km/h. Overall, these findings suggest how MoBI methods may be safely deployed in neural, cognitive, and rehabilitation engineering applications.

  10. Coevolution of variability models and related software artifacts

    DEFF Research Database (Denmark)

    Passos, Leonardo; Teixeira, Leopoldo; Dinztner, Nicolas

    2015-01-01

    models coevolve with other artifact types, we study a large and complex real-world variant-rich software system: the Linux kernel. Specifically, we extract variability-coevolution patterns capturing changes in the variability model of the Linux kernel with subsequent changes in Makefiles and C source...

  11. Artifacts as Theories: Convergence through User-Centered Design.

    Science.gov (United States)

    Dillon, Andrew

    1995-01-01

    Discussion of information system design proposes the artifact as theory perspective and suggests that information system design is best tackled by user-centered theories and methods. Topics include the software development process, human-computer interaction, and implications for information science. (LRW)

  12. Range Condition and ML-EM Checkerboard Artifacts.

    Science.gov (United States)

    You, Jiangsheng; Wang, Jing; Liang, Zhengrong

    2007-10-01

    The expectation maximization (EM) algorithm for the maximum likelihood (ML) image reconstruction criterion generates severe checkerboard artifacts in the presence of noise. A classical remedy is to impose an a priori constraint for a penalized ML or maximum a posteriori probability solution. The penalty reduces the checkerboard artifacts and also introduces uncertainty because a priori information is usually unknown in clinic. Recent theoretical investigation reveals that the noise can be divided into two components: one is called null-space noise and the other is range-space noise. The null-space noise can be numerically estimated using filtered backprojection (FBP) algorithm. By the FBP algorithm, the null-space noise annihilates in the reconstruction while the range-space noise propagates into the reconstructed image. The aim of this work is to investigate the relation between the null-space noise and the checkerboard artifacts in the ML-EM reconstruction from noisy projection data. Our study suggests that removing the null-space noise from the projection data could improve the signal-to-noise ratio of the projection data and, therefore, reduce the checkerboard artifacts in the ML-EM reconstructed images. This study reveals an in-depth understanding of the different noise propagations in analytical and iterative image reconstructions, which may be useful to single photon emission computed tomography, where the noise has been a major factor for image degradation. The reduction of the ML-EM checkerboard artifacts by removing the null-space noise avoids the uncertainty of using a priori penalty.

  13. Assessment of metal artifact reduction methods in pelvic CT

    Energy Technology Data Exchange (ETDEWEB)

    Abdoli, Mehrsima [Department of Radiation Oncology, The Netherlands Cancer Institute, Plesmanlaan 121, Amsterdam 1066 CX (Netherlands); Mehranian, Abolfazl [Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, Geneva CH-1211 (Switzerland); Ailianou, Angeliki; Becker, Minerva [Division of Radiology, Geneva University Hospital, Geneva CH-1211 (Switzerland); Zaidi, Habib, E-mail: habib.zaidi@hcuge.ch [Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, Geneva CH-1211 (Switzerland); Geneva Neuroscience Center, Geneva University, Geneva CH-1205 (Switzerland); Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Hanzeplein 1, Groningen 9700 RB (Netherlands)

    2016-04-15

    Purpose: Metal artifact reduction (MAR) produces images with improved quality potentially leading to confident and reliable clinical diagnosis and therapy planning. In this work, the authors evaluate the performance of five MAR techniques for the assessment of computed tomography images of patients with hip prostheses. Methods: Five MAR algorithms were evaluated using simulation and clinical studies. The algorithms included one-dimensional linear interpolation (LI) of the corrupted projection bins in the sinogram, two-dimensional interpolation (2D), a normalized metal artifact reduction (NMAR) technique, a metal deletion technique, and a maximum a posteriori completion (MAPC) approach. The algorithms were applied to ten simulated datasets as well as 30 clinical studies of patients with metallic hip implants. Qualitative evaluations were performed by two blinded experienced radiologists who ranked overall artifact severity and pelvic organ recognition for each algorithm by assigning scores from zero to five (zero indicating totally obscured organs with no structures identifiable and five indicating recognition with high confidence). Results: Simulation studies revealed that 2D, NMAR, and MAPC techniques performed almost equally well in all regions. LI falls behind the other approaches in terms of reducing dark streaking artifacts as well as preserving unaffected regions (p < 0.05). Visual assessment of clinical datasets revealed the superiority of NMAR and MAPC in the evaluated pelvic organs and in terms of overall image quality. Conclusions: Overall, all methods, except LI, performed equally well in artifact-free regions. Considering both clinical and simulation studies, 2D, NMAR, and MAPC seem to outperform the other techniques.

  14. A no-reference blocking artifact metric for B-DCT video

    Institute of Scientific and Technical Information of China (English)

    YANG Fu-zheng; WAN Shuai; CHANG Yi-lin; LUO Zhong

    2006-01-01

    A new no-reference blocking artifact metric for B-DCT compression video is presented in this paper. We first present a new definition of blocking artifact and a new method for measuring perceptive blocking artifact based on HVS taking into account the luminance masking and activity masking characteristic. Then, we propose a new concept of blocking artifact cluster and the algorithm for clustering blocking artifacts. Considering eye movement and fixation, we select several clusters with most serious blocking artifacts and utilize the average of their blocking artifacts to assess the total blocking artifact of B-DCT reconstructed video. Experimental results illustrating the performance of the proposed method are presented and evaluated.

  15. Keep Your Eye on the Ball: Investigating Artifacts-in-Use in Physical Education

    Science.gov (United States)

    Quennerstedt, Mikael; Almqvist, Jonas; Ohman, Marie

    2011-01-01

    The purpose of this article is to develop a method of approach that can be used to explore the meaning and use of artifacts in education by applying a socio-cultural perspective to learning and artifacts. An empirical material of video recorded physical education lessons in Sweden is used to illustrate the approach in terms of how artifacts in…

  16. Lithic Scatters that Blow: Wind as an Agent of Secondary Deposition of Lithic Artifacts

    Science.gov (United States)

    Artifact presence or absence is frequently the only criteria used to define the horizontal extent of archaeological sites. Artifact transport by natural agents such as water and gravity is known to move artifacts from their primary context, though experimental simulated wind conditions demonstrate t...

  17. Generic Language Use Reveals Domain Differences in Young Children's Expectations about Animal and Artifact Categories

    Science.gov (United States)

    Brandone, Amanda C.; Gelman, Susan A.

    2013-01-01

    The goal of the present study was to explore domain differences in young children's expectations about the structure of animal and artifact categories. We examined 5-year-olds' and adults' use of category-referring generic noun phrases (e.g., "Birds fly") about novel animals and artifacts. The same stimuli served as both animals and artifacts;…

  18. Quantitative Comparison of Commercial and Non-Commercial Metal Artifact Reduction Techniques in Computed Tomography

    NARCIS (Netherlands)

    Wagenaar, Dirk; van der Graaf, Emiel R.; van der Schaaf, Arjen; Greuter, Marcel J. W.

    2015-01-01

    Objectives Typical streak artifacts known as metal artifacts occur in the presence of strongly attenuating materials in computed tomography (CT). Recently, vendors have started offering metal artifact reduction (MAR) techniques. In addition, a MAR technique called the metal deletion technique (MDT)

  19. Adiabatic low-pass J filters for artifact suppression in heteronuclear NMR.

    Science.gov (United States)

    Meier, Sebastian; Benie, Andrew J; Duus, Jens Ø; Sørensen, Ole W

    2009-04-14

    NMR artifact purging: Modern NMR experiments depend on efficient coherence transfer pathways for their sensitivity and on suppression of undesired pathways leading to artifacts for their spectral clarity. A novel robust adiabatic element suppresses hard-to-get-at artifacts (see picture).

  20. Reduction of aneurysm clip artifacts on CT angiograms: a technical note.

    Science.gov (United States)

    Brown, J H; Lustrin, E S; Lev, M H; Ogilvy, C S; Taveras, J M

    1999-04-01

    We describe a head tilt technique for use with CT angiography that reduces beam-hardening artifacts in patients with aneurysm clips. This simple maneuver directs the artifacts away from pertinent anatomy, thus increasing the chances for diagnostic accuracy. No significant changes in the CT angiographic protocol are required, and the maneuver can easily be combined with other artifact-minimizing strategies.

  1. Digital Library Archaeology: A Conceptual Framework for Understanding Library Use through Artifact-Based Evaluation

    Science.gov (United States)

    Nicholson, Scott

    2005-01-01

    Archaeologists have used material artifacts found in a physical space to gain an understanding about the people who occupied that space. Likewise, as users wander through a digital library, they leave behind data-based artifacts of their activity in the virtual space. Digital library archaeologists can gather these artifacts and employ inductive…

  2. Improved lumen visualization in metallic vascular implants by reducing RF artifacts

    NARCIS (Netherlands)

    Bartels, LW; Bakker, CJG; Viergever, MA

    2002-01-01

    In this study, a method is proposed for MRI of the lumen of metallic vascular implants, like stents or vena cava filters. The method is based on the reduction of artifacts caused by flow, susceptibility, and RIF eddy currents. Whereas both flow artifacts and susceptibility artifacts are well underst

  3. TH-C-BRD-06: A Novel MRI Based CT Artifact Correction Method for Improving Proton Range Calculation in the Presence of Severe CT Artifacts

    Energy Technology Data Exchange (ETDEWEB)

    Park, P; Schreibmann, E; Fox, T; Roper, J; Elder, E; Tejani, M; Crocker, I; Curran, W; Dhabaan, A [Department of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, GA (United States)

    2014-06-15

    Purpose: Severe CT artifacts can impair our ability to accurately calculate proton range thereby resulting in a clinically unacceptable treatment plan. In this work, we investigated a novel CT artifact correction method based on a coregistered MRI and investigated its ability to estimate CT HU and proton range in the presence of severe CT artifacts. Methods: The proposed method corrects corrupted CT data using a coregistered MRI to guide the mapping of CT values from a nearby artifact-free region. First patient MRI and CT images were registered using 3D deformable image registration software based on B-spline and mutual information. The CT slice with severe artifacts was selected as well as a nearby slice free of artifacts (e.g. 1cm away from the artifact). The two sets of paired MRI and CT images at different slice locations were further registered by applying 2D deformable image registration. Based on the artifact free paired MRI and CT images, a comprehensive geospatial analysis was performed to predict the correct CT HU of the CT image with severe artifact. For a proof of concept, a known artifact was introduced that changed the ground truth CT HU value up to 30% and up to 5cm error in proton range. The ability of the proposed method to recover the ground truth was quantified using a selected head and neck case. Results: A significant improvement in image quality was observed visually. Our proof of concept study showed that 90% of area that had 30% errors in CT HU was corrected to 3% of its ground truth value. Furthermore, the maximum proton range error up to 5cm was reduced to 4mm error. Conclusion: MRI based CT artifact correction method can improve CT image quality and proton range calculation for patients with severe CT artifacts.

  4. Gibbs artifact reduction for POCS super-resolution image reconstruction

    Institute of Scientific and Technical Information of China (English)

    Chuangbai XIAO; Jing YU; Kaina SU

    2008-01-01

    The topic of super-resolution image reconstruc-tion has recently received considerable attention among the research community. Super-resolution image reconstruc-tion methods attempt to create a single high-resolution image from a number of low-resolution images (or a video sequence). The method of projections onto convex sets (POCS) for super-resolution image reconstruction attracts many researchers' attention. In this paper, we propose an improvement to reduce the amount of Gibbs artifacts pre-senting on the edges of the high-resolution image recon-structed by the POCS method. The proposed method weights the blur PSF centered at an edge pixel with an exponential function, and consequently decreases the coef-ficients of the PSF in the direction orthogonal to the edge. Experiment results show that the modification reduces effectively the visibility of Gibbs artifacts on edges and improves obviously the quality of the reconstructed high-resolution image.

  5. Coulomb Artifacts and Bottomonium Hyperfine Splitting in Lattice NRQCD

    CERN Document Server

    Liu, Tao; Rayyan, Ahmed

    2016-01-01

    We study the role of the lattice artifacts associated with the Coulomb binding effects in the analysis of the heavy quarkonium within lattice NRQCD. We find that a "na\\"ive" perturbative matching generates spurious linear Coulomb artifacts, which result in a large systematic error in the lattice predictions for the heavy quarkonium spectrum. This effect is responsible, in particular, for the discrepancy between the recent determinations of the bottomonium hyperfine splitting in the radiatively improved lattice NRQCD [1, 2]. We show that the correct matching procedure which provides full control over discretization errors is based on the asymptotic expansion of the lattice theory about the continuum limit, which gives $M_{\\Upsilon(1S)}-M_{\\eta_b(1S)}=52.9\\pm 5.5~{\\rm MeV}$ [1].

  6. Taxonomy development and knowledge representation of nurses' personal cognitive artifacts.

    Science.gov (United States)

    McLane, Sharon; Turley, James P

    2009-11-14

    Nurses prepare knowledge representations, or summaries of patient clinical data, each shift. These knowledge representations serve multiple purposes, including support of working memory, workload organization and prioritization, critical thinking, and reflection. This summary is integral to internal knowledge representations, working memory, and decision-making. Study of this nurse knowledge representation resulted in development of a taxonomy of knowledge representations necessary to nursing practice.This paper describes the methods used to elicit the knowledge representations and structures necessary for the work of clinical nurses, described the development of a taxonomy of this knowledge representation, and discusses translation of this methodology to the cognitive artifacts of other disciplines. Understanding the development and purpose of practitioner's knowledge representations provides important direction to informaticists seeking to create information technology alternatives. The outcome of this paper is to suggest a process template for transition of cognitive artifacts to an information system.

  7. Woodworm Disinfestation of Wooden Artifacts by Vacuum Techniques

    Directory of Open Access Journals (Sweden)

    Giuseppe Chidichimo

    2015-12-01

    Full Text Available Wooden artifacts are subject to being heavily damaged by the attack of worms which develop in the wood through the eggs deposited by adult pests before their final transformation into flying insects. Among the most dangerous species are xylophagous (wood-boring insects, whose larvae are responsible for one of the most efficient wood-destroying mechanisms in wooden cultural heritage. Their elimination has always been a huge problem for the conservation of wood. In this work, we present the experimentation of a simple vacuum technique to disinfest wood from the larval Hylotrupes bajolus. We will also introduce the possibility of treating large-sized wooden artifacts by means of a special vacuum chamber.

  8. Optical nano artifact metrics using silicon random nanostructures

    CERN Document Server

    Matsumoto, Tsutomu; Nishio, Shumpei; Hoga, Morihisa; Ohyagi, Yasuyuki; Tate, Naoya; Naruse, Makoto

    2016-01-01

    Nano artifact metrics exploit unique physical attributes of nanostructured matter for authentication and clone resistance, which is vitally important in the age of Internet-of-Things where securing identities is critical. However, high-cost and huge experimental apparatuses, such as scanning electron microscopy, have been required in the former studies. Herein, we demonstrate an optical approach to characterise the nanoscale-precision signatures of silicon random structures towards realising low-cost and high-value information security technology. Unique and versatile silicon nanostructures are generated via resist collapse phenomena, which contains dimensions that are well below the diffraction limit of light. We exploit the nanoscale precision ability of confocal laser microscopy in the height dimension, and our experimental results demonstrate that the vertical precision of measurement is essential in satisfying the performances required for artifact metrics. Furthermore, by using state-of-the-art nanostru...

  9. Coevolution of variability models and related software artifacts

    DEFF Research Database (Denmark)

    Passos, Leonardo; Teixeira, Leopoldo; Dinztner, Nicolas;

    2015-01-01

    to the evolution of different kinds of software artifacts, it is not surprising that industry reports existing tools and solutions ineffective, as they do not handle the complexity found in practice. Attempting to mitigate this overall lack of knowledge and to support tool builders with insights on how variability...... models coevolve with other artifact types, we study a large and complex real-world variant-rich software system: the Linux kernel. Specifically, we extract variability-coevolution patterns capturing changes in the variability model of the Linux kernel with subsequent changes in Makefiles and C source......Variant-rich software systems offer a large degree of customization, allowing users to configure the target system according to their preferences and needs. Facing high degrees of variability, these systems often employ variability models to explicitly capture user-configurable features (e...

  10. Santeria and Palo Mayombe: skulls, mercury, and artifacts.

    Science.gov (United States)

    Gill, James R; Rainwater, Christopher W; Adams, Bradley J

    2009-11-01

    Santeria and Palo Mayombe are syncretic religions created in the New World based upon African religious beliefs combined with Christianity. The main worship of Palo Mayombe involves religious receptacles that may contain earth, sticks, varied artifacts, and animal and human remains. Due to the use of human and nonhuman remains, discovery of these items often leads to involvement by the police due to a concern of homicide. We review in detail the medical examiner records of two of these ritualistic cases including the autopsy, anthropology, police, and investigators' reports. For the human remains, careful consideration of the context in which the remains were recovered, their state of preservation, and the associated artifacts (e.g., beads and mercury) are important in determining the appropriate level of forensic significance. Anthropological examination with particular attention to taphonomic characteristics also may help determine the origin and forensic significance.

  11. Regulator Artifacts in Uniform Matter for Chiral Interactions

    CERN Document Server

    Dyhdalo, A; Hebeler, K; Tews, I

    2016-01-01

    Regulator functions applied to two- and three-nucleon forces are a necessary ingredient in many-body calculations based on chiral effective field theory interactions. These interactions have been developed recently with a variety of different cutoff forms, including regulating both the momentum transfer (local) and the relative momentum (nonlocal). While in principle any regulator that suppresses high momentum modes can be employed, in practice artifacts are inevitable in current power counting schemes. Artifacts from particular regulators may cause significant distortions of the physics or may affect many-body convergence rates, so understanding their nature is important. Here we characterize the differences between cutoff effects using uniform matter at Hartree-Fock and second-order in the interaction as a testbed. This provides a clean laboratory to isolate phase-space effects of various regulators on both two- and three-nucleon interactions. We test the normal-ordering approximation for three-nucleon forc...

  12. Approaches to eliminate near field artifact of MURA

    Institute of Scientific and Technical Information of China (English)

    WANG Ren-Song; RONG Jun-Yan; WEI Long

    2008-01-01

    Since the coded aperture technique has been successfully applied on X-ray imaging space telescopes, attentions of its development have also been cast on the application in medical imaging, for it has a very tempting quality to greatly enhance the detection sensitivity without gravely lowering the spacial resolution. But when the coded aperture technique is applied to image a nearby object, the so called "near-field artifact"comes up, that is, the reconstructed image has a sort of distortion. Among types of coded apertures the MURA (Modified Uniformly Redundant Array) is one of the most discussed. Roberto Arrcosi came up with the solution to remove the artifacts utilizing mask and antimask. In this article we present two ways to eliminate the second order aberration based on his work.

  13. Development of tools and techniques for monitoring underwater artifacts

    Science.gov (United States)

    Lazar, Iulian; Ghilezan, Alin; Hnatiuc, Mihaela

    2016-12-01

    The different assessments provide information on the best methods to approach an artifact. The presence and extent of potential threats to archaeology must also be determined. In this paper we present an underwater robot, built in the laboratory, able to identify the artifact and to get it to the surface. It is an underwater remotely operated vehicle (ROV) which can be controlled remotely from the shore, a boat or a control station and communication is possible through an Ethernet cable with a maximum length of 100 m. The robot is equipped with an IP camera which sends real time images that can be accessed anywhere from within the network. The camera also has a microSD card to store the video. The methods developed for data communication between the robot and the user is present. A communication protocol between the client and server is developed to control the ROV.

  14. Dental artifacts in the head and neck region:

    DEFF Research Database (Denmark)

    Ladefoged, Claes N.; Hansen, Adam E.; Keller, Sune;

    2015-01-01

    images were evaluated visually and quantitatively using regions of interests in reference regions. The volume of the artifacts and the computed relative differences in mean and max standardized uptake value (SUV) between the two PET images are reported. RESULTS: The MR-based volume of the susceptibility......-induced signal voids on the MR-AC attenuation maps was between 1.6 and 520.8 mL. The corresponding/resulting bias of the reconstructed tracer distribution was localized mainly in the area of the signal void. The mean and maximum SUVs averaged across all patients increased after inpainting by 52% (± 11%) and 28......% (± 11%), respectively, in the corrected region. SUV underestimation decreased with the distance to the signal void and correlated with the volume of the susceptibility artifact on the MR-AC attenuation map. CONCLUSIONS: Metallic dental work may cause severe MR signal voids. The resulting PET...

  15. Interpolation strategies for reducing IFOV artifacts in microgrid polarimeter imagery.

    Science.gov (United States)

    Ratliff, Bradley M; LaCasse, Charles F; Tyo, J Scott

    2009-05-25

    Microgrid polarimeters are composed of an array of micro-polarizing elements overlaid upon an FPA sensor. In the past decade systems have been designed and built in all regions of the optical spectrum. These systems have rugged, compact designs and the ability to obtain a complete set of polarimetric measurements during a single image capture. However, these systems acquire the polarization measurements through spatial modulation and each measurement has a varying instantaneous field-of-view (IFOV). When these measurements are combined to estimate the polarization images, strong edge artifacts are present that severely degrade the estimated polarization imagery. These artifacts can be reduced when interpolation strategies are first applied to the intensity data prior to Stokes vector estimation. Here we formally study IFOV error and the performance of several bilinear interpolation strategies used for reducing it.

  16. 减少头部运动伪影及磁敏感伪影的propller技术应用价值评价%To Reduce the Head Motion Artifact and Magnetic Sensitive Artifacts Propller Technology Application Value Evaluation

    Institute of Scientific and Technical Information of China (English)

    刘海博

    2015-01-01

    目的:探讨 Propl er 技术对减少头部运动伪影及磁敏感伪影的应用价值。方法我院于2010年3月至2013年对55例磁共振头颅检查时躁动或难以自控的患者,进行常规 FRFSE T2WI 和 Propel er T2WI 轴位扫描;对33例磁敏感伪影明显者行常规扩散加权图像(DWI)和Propel er DWI 扫描。观察并对照分析 FRFSE T2WI 和 Propel er T2WI 以及 DWI 与 Propel er DWI 的图像质量状况。结果通过 T2WI 检查55例,对存在明显运动伪影的患者行 Propel er T2WI 扫描后明显减少或消除了运动伪影,与 T2WI 检查结果相比差异明显,具有统计学意义(P<0.05)。DWI 检查33例患者有显著磁敏感伪影,采用 ProDel er DWI 后,与 DWI 检查结果相比差异明显,具有统计学意义(P<0.05)。结论应用 Propel er 技术能够明显减少或消除 T2WI 及 DWI 上运动伪影及磁敏感伪影,值得推广应用。%Objective To study the Propl er technology to reduce the head motion artifact and the application value of the magnetic sensitive artifact. Methods Our hospital from March 2010 to 2013, 55 cases of MRI head check agitation or patients with difficult to control, for regular FRFSE T2WI and Propel er T2WI axial scanning; 33 cases of magnetic sensitive artifact obvious line of conventional diffusion weighted image (DWI) can and Propel er DWI scan can. Observation and contrast analysis FRFSE T2WI and Propel er T2WI and DWI and Propel er can DWI image quality can. Results Through T2WI check 55 cases of patients with obvious motion artifact line Propel er T2WI scan significantly reduce or eliminate the motion artifacts, clear difference compared with T2WI results, with statistical significance (P < 0.05). DWI examination can 33 patients had significant magnetic sensitive artifacts, adopting ProDeller DWI, can clear difference compared with DWI results can, with statistical significance (P < 0.05). Conclusion Application of Propel er technology

  17. A sign of the times: contemporary dental imaging artifacts.

    Science.gov (United States)

    Frommer, Herbert H; Stabulas-Savage, Jeanine J

    2008-11-01

    There have been new findings evident in dental imaging that reflect changes in society over time. Although we may interpret these findings as "artifacts," they could simply be images that we cannot readily identify. The following article is presented to notify dental professionals of the presence of these images, which are truly "signs of the times," and to assist clinicians in recognizing these images in dental radiography.

  18. The mineralogical and fabric analysis of ancient pottery artifacts

    OpenAIRE

    R. Palanivel; Rajesh Kumar,U.

    2011-01-01

    The present investigation is carried out to estimate the firing temperature and conditions of firing of ancient pottery shreds excavated recently from Sembiankandiyur, Tamil Nadu, India. FTIR and XRD studies have been attempted on these shreds to characterize the mineral composition of the pottery artifacts in respect of their different physical attributes. The firing temperature and conditions were inferred from the mineral phases of the samples exhibited by the infrared spectra and X-ray di...

  19. Carbon fiber intramedullary nails reduce artifact in postoperative advanced imaging

    Energy Technology Data Exchange (ETDEWEB)

    Zimel, Melissa N. [Memorial Sloan Kettering Cancer Center, Orthopaedic Surgery Service, Department of Surgery, New York, NY (United States); Hwang, Sinchun [Memorial Sloan Kettering Cancer Center, Department of Radiology, New York, NY (United States); Riedel, Elyn R. [Memorial Sloan Kettering Cancer Center, Department of Epidemiology and Biostatistics, New York, NY (United States); Healey, John H. [Memorial Sloan Kettering Cancer Center, Orthopaedic Surgery Service, Department of Surgery, New York, NY (United States); Weill Medical College of Cornell University, Department of Orthopaedic Surgery, New York, NY (United States)

    2015-09-15

    This study assessed whether radiolucent carbon fiber reinforced-polyetheretherketone (CFR-PEEK) intramedullary nails decreased hardware artifact on magnetic resonance imaging (MRI) and computed tomography (CT) in vitro and in an oncologic patient population. In vitro and clinical evaluations were done. A qualitative assessment of metal artifact was performed using CFR-PEEK and titanium nail MRI phantoms. Eight patients with a femoral or tibial prophylactic CFR-PEEK nail were retrospectively identified. All patients had postoperative surveillance imaging by MRI, CT, and were followed for a median 20 months (range, 12-28 months). CFR-PEEK images were compared to images from a comparative group of patients with titanium femoral intramedullary nails who had a postoperative MRI or CT. A musculoskeletal-trained radiologist graded visualization of the cortex, corticomedullary junction, and bone-muscle interface, on T1-weighted (T1W), STIR, and contrast-enhanced T1-weighted fat-saturated (T1W FS) sequences of both groups with a five-point scale, performing independent reviews 4 months apart. Statistical analysis used the Wilcoxon rank-sum test and a weighted kappa. Substantially less MRI signal loss occurred in the CFR-PEEK phantom than in the titanium phantom simulation, particularly as the angle increased with respect to direction of the static magnetic field. CFR-PEEK nails had less MRI artifact than titanium nails on scored T1W, STIR, and contrast-enhanced T1W FS MRI sequences (p ≤ 0.03). The mean weighted kappa was 0.64, showing excellent intraobserver reliability between readings. CFR-PEEK intramedullary nail fixation is a superior alternative to minimize implant artifact on MRI or CT imaging for patients requiring long bone fixation. (orig.)

  20. Buildings as Artifacts: Heritage, Patriotism, and the Constructed Landscape

    OpenAIRE

    Kristin Marie Barry

    2017-01-01

    Architectural collections or reconstructed villages are popular tourist attractions in Europe and the United States, often promoting architecture as a demonstration of national and regional heritages. At times, these sites betray the biases of their creators, perpetuated through methods of display and their public interpretation. The architecture can be used as artifact or backdrop to promote ethics, history, or industry at the hand of curators, particularly when removed from its original con...

  1. Methods of preparing polyimides and artifacts composed thereof

    Science.gov (United States)

    Gagliani, John (Inventor); Lee, Raymond (Inventor); Wilcoxson, Anthony L. (Inventor)

    1984-01-01

    Methods of converting essentially unpolymerized precursors into polyimides in which the precursors are exposed to microwave radiation. Preheating, thermal post-curing, and other techniques may be employed to promote the development of optimum properties; and reinforcements can be employed to impart strength and rigidity to the final product. Also disclosed are processes for making various composite artifacts in which non-polymeric precursors are converted to polyimides by using the techniques described above.

  2. Accelerated Edge-Preserving Image Restoration Without Boundary Artifacts

    OpenAIRE

    Matakos, Antonios; Ramani, Sathish; Fessler, Jeffrey A.

    2013-01-01

    To reduce blur in noisy images, regularized image restoration methods have been proposed that use non-quadratic regularizers (like l1 regularization or total-variation) that suppress noise while preserving edges in the image. Most of these methods assume a circulant blur (periodic convolution with a blurring kernel) that can lead to wraparound artifacts along the boundaries of the image due to the implied periodicity of the circulant model. Using a non-circulant model could prevent these arti...

  3. Mitigating artifacts via half-time reconstruction in thermoacoustic tomography

    Science.gov (United States)

    Anastasio, Mark A.; Zhang, Jin; Pan, Xiaochuan; Ku, Geng; Wang, Lihong V.

    2005-04-01

    Thermoacoustic tomography (TAT) is an ultrasound-mediated biophotonic imaging modality with great potential for a wide range of biomedical imaging applications. In this work, we demonstrate that half-time reconstruction approaches for TAT can mitigate image artifacts due to heterogeneous acoustic properties of an object. We also discuss how half-time reconstruction approaches permit explicit control of statistically complementary information in the measurement data, which can facilitate the reduction of image variances.

  4. A frequency domain based rigid motion artifact reduction algorithm

    Science.gov (United States)

    Luo, Hai; Huang, Xiaojie; Pan, Wenyu; Zhou, Heqin; Feng, Huanqing

    2009-10-01

    During a CT scan, patients' conscious or unconscious motions would result in motion artifacts which undermine the image quality and hamper doctors' accurate diagnosis and therapy. It is desirable to develop a precise motion estimation and artifact reduction method in order to produce high-resolution images. Rigid motion can be decomposed into two components: translational motion and rotational motion. Since considering the rotation and translation simultaneously is very difficult, most former studies on motion artifact reduction ignore rotation. The extended HLCC based method considering the rotation and translation simultaneously relies on a searching algorithm which leads to expensive computing cost. Therefore, a novel method which does not rely on searching is desirable. In this paper, we focus on parallel-beam CT. We first propose a frequency domain based method to estimate rotational motion, which is not affected by translational motion. It realizes the separation of rotation estimation and translation estimation. Then we combine this method with the HLCC based method to construct a new method for general rigid motion called separative estimation and collective correction method. Furthermore, we present numerical simulation results to show the accuracy and robustness of our approach.

  5. Dynamic Gate Product and Artifact Generation from System Models

    Science.gov (United States)

    Jackson, Maddalena

    2011-01-01

    Model Based Systems Engineering (MBSE) is gaining acceptance as a way to formalize systems engineering practice through the use of models. The traditional method of producing and managing a plethora of disjointed documents and presentations ("Power-Point Engineering") has proven both costly and limiting as a means to manage the complex and sophisticated specifications of modern space systems. We have developed a tool and method to produce sophisticated artifacts as views and by-products of integrated models, allowing us to minimize the practice of "Power-Point Engineering" from model-based projects and demonstrate the ability of MBSE to work within and supersede traditional engineering practices. This paper describes how we have created and successfully used model-based document generation techniques to extract paper artifacts from complex SysML and UML models in support of successful project reviews. Use of formal SysML and UML models for architecture and system design enables production of review documents, textual artifacts, and analyses that are consistent with one-another and require virtually no labor-intensive maintenance across small-scale design changes and multiple authors. This effort thus enables approaches that focus more on rigorous engineering work and less on "PowerPoint engineering" and production of paper-based documents or their "office-productivity" file equivalents.

  6. Ratiometric artifact reduction in low power reflective photoplethysmography.

    Science.gov (United States)

    Patterson, J A C; Guang-Zhong Yang

    2011-08-01

    This paper presents effective signal-processing techniques for the compensation of motion artifacts and ambient light offsets in a reflective photoplethysmography sensor suitable for wearable applications. A ratiometric comparison of infrared (IR) and red absorption characteristics cancels out noise that is multiplicative in nature and amplitude modulation of pulsatile absorption signals enables rejection of additive noise. A low-power, discrete-time pulse-oximeter platform is used to capture IR and red photoplethysmograms so that the data used for analysis have noise levels representative of what a true body sensor network device would experience. The proposed artifact rejection algorithm is designed for real-time implementation with a low-power microcontroller while being robust enough to compensate for varying levels in ambient light as well as reducing the effects of motion-induced artifacts. The performance of the system is illustrated by its ability to extract a typical plethysmogram heart-rate waveform since the sensor is subjected to a range of physical disturbances.

  7. Accelerated edge-preserving image restoration without boundary artifacts.

    Science.gov (United States)

    Matakos, Antonios; Ramani, Sathish; Fessler, Jeffrey A

    2013-05-01

    To reduce blur in noisy images, regularized image restoration methods have been proposed that use nonquadratic regularizers (like l1 regularization or total-variation) that suppress noise while preserving edges in the image. Most of these methods assume a circulant blur (periodic convolution with a blurring kernel) that can lead to wraparound artifacts along the boundaries of the image due to the implied periodicity of the circulant model. Using a noncirculant model could prevent these artifacts at the cost of increased computational complexity. In this paper, we propose to use a circulant blur model combined with a masking operator that prevents wraparound artifacts. The resulting model is noncirculant, so we propose an efficient algorithm using variable splitting and augmented Lagrangian (AL) strategies. Our variable splitting scheme, when combined with the AL framework and alternating minimization, leads to simple linear systems that can be solved noniteratively using fast Fourier transforms (FFTs), eliminating the need for more expensive conjugate gradient-type solvers. The proposed method can also efficiently tackle a variety of convex regularizers, including edge-preserving (e.g., total-variation) and sparsity promoting (e.g., l1-norm) regularizers. Simulation results show fast convergence of the proposed method, along with improved image quality at the boundaries where the circulant model is inaccurate.

  8. Accelerated Edge-Preserving Image Restoration Without Boundary Artifacts

    Science.gov (United States)

    Matakos, Antonios; Ramani, Sathish; Fessler, Jeffrey A.

    2013-01-01

    To reduce blur in noisy images, regularized image restoration methods have been proposed that use non-quadratic regularizers (like l1 regularization or total-variation) that suppress noise while preserving edges in the image. Most of these methods assume a circulant blur (periodic convolution with a blurring kernel) that can lead to wraparound artifacts along the boundaries of the image due to the implied periodicity of the circulant model. Using a non-circulant model could prevent these artifacts at the cost of increased computational complexity. In this work we propose to use a circulant blur model combined with a masking operator that prevents wraparound artifacts. The resulting model is non-circulant, so we propose an efficient algorithm using variable splitting and augmented Lagrangian (AL) strategies. Our variable splitting scheme, when combined with the AL framework and alternating minimization, leads to simple linear systems that can be solved non-iteratively using FFTs, eliminating the need for more expensive CG-type solvers. The proposed method can also efficiently tackle a variety of convex regularizers including edge-preserving (e.g., total-variation) and sparsity promoting (e.g., l1 norm) regularizers. Simulation results show fast convergence of the proposed method, along with improved image quality at the boundaries where the circulant model is inaccurate. PMID:23372080

  9. Joint correction of Nyquist artifact and minuscule motion-induced aliasing artifact in interleaved diffusion weighted EPI data using a composite two-dimensional phase correction procedure.

    Science.gov (United States)

    Chang, Hing-Chiu; Chen, Nan-Kuei

    2016-09-01

    Diffusion-weighted imaging (DWI) obtained with interleaved echo-planar imaging (EPI) pulse sequence has great potential of characterizing brain tissue properties at high spatial-resolution. However, interleaved EPI based DWI data may be corrupted by various types of aliasing artifacts. First, inconsistencies in k-space data obtained with opposite readout gradient polarities result in Nyquist artifact, which is usually reduced with 1D phase correction in post-processing. When there exist eddy current cross terms (e.g., in oblique-plane EPI), 2D phase correction is needed to effectively reduce Nyquist artifact. Second, minuscule motion induced phase inconsistencies in interleaved DWI scans result in image-domain aliasing artifact, which can be removed with reconstruction procedures that take shot-to-shot phase variations into consideration. In existing interleaved DWI reconstruction procedures, Nyquist artifact and minuscule motion-induced aliasing artifact are typically removed subsequently in two stages. Although the two-stage phase correction generally performs well for non-oblique plane EPI data obtained from well-calibrated system, the residual artifacts may still be pronounced in oblique-plane EPI data or when there exist eddy current cross terms. To address this challenge, here we report a new composite 2D phase correction procedure, which effective removes Nyquist artifact and minuscule motion induced aliasing artifact jointly in a single step. Our experimental results demonstrate that the new 2D phase correction method can much more effectively reduce artifacts in interleaved EPI based DWI data as compared with the existing two-stage artifact correction procedures. The new method robustly enables high-resolution DWI, and should prove highly valuable for clinical uses and research studies of DWI.

  10. Isolating gait-related movement artifacts in electroencephalography during human walking

    Science.gov (United States)

    Kline, Julia E.; Huang, Helen J.; Snyder, Kristine L.; Ferris, Daniel P.

    2015-08-01

    Objective. High-density electroencephelography (EEG) can provide an insight into human brain function during real-world activities with walking. Some recent studies have used EEG to characterize brain activity during walking, but the relative contributions of movement artifact and electrocortical activity have been difficult to quantify. We aimed to characterize movement artifact recorded by EEG electrodes at a range of walking speeds and to test the efficacy of artifact removal methods. We also quantified the similarity between movement artifact recorded by EEG electrodes and a head-mounted accelerometer. Approach. We used a novel experimental method to isolate and record movement artifact with EEG electrodes during walking. We blocked electrophysiological signals using a nonconductive layer (silicone swim cap) and simulated an electrically conductive scalp on top of the swim cap using a wig coated with conductive gel. We recorded motion artifact EEG data from nine young human subjects walking on a treadmill at speeds from 0.4 to 1.6 m s-1. We then tested artifact removal methods including moving average and wavelet-based techniques. Main results. Movement artifact recorded with EEG electrodes varied considerably, across speed, subject, and electrode location. The movement artifact measured with EEG electrodes did not correlate well with head acceleration. All of the tested artifact removal methods attenuated low-frequency noise but did not completely remove movement artifact. The spectral power fluctuations in the movement artifact data resembled data from some previously published studies of EEG during walking. Significance. Our results suggest that EEG data recorded during walking likely contains substantial movement artifact that: cannot be explained by head accelerations; varies across speed, subject, and channel; and cannot be removed using traditional signal processing methods. Future studies should focus on more sophisticated methods for removal of EEG

  11. Iterative metal artifact reduction: Evaluation and optimization of technique

    Energy Technology Data Exchange (ETDEWEB)

    Subhas, Naveen; Gupta, Amit; Polster, Joshua M. [Imaging Institute, Cleveland Clinic, Cleveland, OH (United States); Primak, Andrew N. [Siemens Medical Solutions USA Inc., Malvern, PA (United States); Obuchowski, Nancy A. [Quantitative Health Sciences, Cleveland Clinic, Cleveland, OH (United States); Krauss, Andreas [Siemens Healthcare, Forchheim (Germany); Iannotti, Joseph P. [Orthopaedic and Rheumatologic Institute, Cleveland Clinic, Cleveland, OH (United States)

    2014-12-15

    Iterative metal artifact reduction (IMAR) is a sinogram inpainting technique that incorporates high-frequency data from standard weighted filtered back projection (WFBP) reconstructions to reduce metal artifact on computed tomography (CT). This study was designed to compare the image quality of IMAR and WFBP in total shoulder arthroplasties (TSA); determine the optimal amount of WFBP high-frequency data needed for IMAR; and compare image quality of the standard 3D technique with that of a faster 2D technique. Eight patients with nine TSA underwent CT with standardized parameters: 140 kVp, 300 mAs, 0.6 mm collimation and slice thickness, and B30 kernel. WFBP, three 3D IMAR algorithms with different amounts of WFBP high-frequency data (IMARlo, lowest; IMARmod, moderate; IMARhi, highest), and one 2D IMAR algorithm were reconstructed. Differences in attenuation near hardware and away from hardware were measured and compared using repeated measures ANOVA. Five readers independently graded image quality; scores were compared using Friedman's test. Attenuation differences were smaller with all 3D IMAR techniques than with WFBP (p < 0.0063). With increasing high-frequency data, the attenuation difference increased slightly (differences not statistically significant). All readers ranked IMARmod and IMARhi more favorably than WFBP (p < 0.05), with IMARmod ranked highest for most structures. The attenuation difference was slightly higher with 2D than with 3D IMAR, with no significant reader preference for 3D over 2D. IMAR significantly decreases metal artifact compared to WFBP both objectively and subjectively in TSA. The incorporation of a moderate amount of WFBP high-frequency data and use of a 2D reconstruction technique optimize image quality and allow for relatively short reconstruction times. (orig.)

  12. Reference-free removal of EEG-fMRI ballistocardiogram artifacts with harmonic regression.

    Science.gov (United States)

    Krishnaswamy, Pavitra; Bonmassar, Giorgio; Poulsen, Catherine; Pierce, Eric T; Purdon, Patrick L; Brown, Emery N

    2016-03-01

    Combining electroencephalogram (EEG) recording and functional magnetic resonance imaging (fMRI) offers the potential for imaging brain activity with high spatial and temporal resolution. This potential remains limited by the significant ballistocardiogram (BCG) artifacts induced in the EEG by cardiac pulsation-related head movement within the magnetic field. We model the BCG artifact using a harmonic basis, pose the artifact removal problem as a local harmonic regression analysis, and develop an efficient maximum likelihood algorithm to estimate and remove BCG artifacts. Our analysis paradigm accounts for time-frequency overlap between the BCG artifacts and neurophysiologic EEG signals, and tracks the spatiotemporal variations in both the artifact and the signal. We evaluate performance on: simulated oscillatory and evoked responses constructed with realistic artifacts; actual anesthesia-induced oscillatory recordings; and actual visual evoked potential recordings. In each case, the local harmonic regression analysis effectively removes the BCG artifacts, and recovers the neurophysiologic EEG signals. We further show that our algorithm outperforms commonly used reference-based and component analysis techniques, particularly in low SNR conditions, the presence of significant time-frequency overlap between the artifact and the signal, and/or large spatiotemporal variations in the BCG. Because our algorithm does not require reference signals and has low computational complexity, it offers a practical tool for removing BCG artifacts from EEG data recorded in combination with fMRI.

  13. Artifacts in magnetic resonance imaging and computed tomography caused by dental materials.

    Directory of Open Access Journals (Sweden)

    Thomas Klinke

    Full Text Available BACKGROUND: Artifacts caused by dental restorations, such as dental crowns, dental fillings and orthodontic appliances, are a common problem in MRI and CT scans of the head and neck. The aim of this in-vitro study was to identify and evaluate the artifacts produced by different dental restoration materials in CT and MRI images. METHODS: Test samples of 44 materials (Metal and Non-Metal commonly used in dental restorations were fabricated and embedded with reference specimens in gelatin moulds. MRI imaging of 1.5T and CT scan were performed on the samples and evaluated in two dimensions. Artifact size and distortions were measured using a digital image analysis software. RESULTS: In MRI, 13 out of 44 materials produced artifacts, while in CT 41 out of 44 materials showed artifacts. Artifacts produced in both MRI and CT images were categorized according to the size of the artifact. SIGNIFICANCE: Metal based restoration materials had strong influence on CT and less artifacts in MRI images. Rare earth elements such as Ytterbium trifluoride found in composites caused artifacts in both MRI and CT. Recognizing these findings would help dental materials manufacturers and developers to produce materials which can cause less artifacts in MRI and CT images.

  14. Ring artifacts removal via spatial sparse representation in cone beam CT

    Science.gov (United States)

    Li, Zhongyuan; Li, Guang; Sun, Yi; Luo, Shouhua

    2016-03-01

    This paper is about the ring artifacts removal method in cone beam CT. Cone beam CT images often suffer from disturbance of ring artifacts which caused by the non-uniform responses of the elements in detectors. Conventional ring artifacts removal methods focus on the correlation of the elements and the ring artifacts' structural characteristics in either sinogram domain or cross-section image. The challenge in the conventional methods is how to distinguish the artifacts from the intrinsic structures; hence they often give rise to the blurred image results due to over processing. In this paper, we investigate the characteristics of the ring artifacts in spatial space, different from the continuous essence of 3D texture feature of the scanned objects, the ring artifacts are displayed discontinuously in spatial space, specifically along z-axis. Thus we can easily recognize the ring artifacts in spatial space than in cross-section. As a result, we choose dictionary representation for ring artifacts removal due to its high sensitivity to structural information. We verified our theory both in spatial space and coronal-section, the experimental results demonstrate that our methods can remove the artifacts efficiently while maintaining image details.

  15. SU-E-I-38: Improved Metal Artifact Correction Using Adaptive Dual Energy Calibration

    Energy Technology Data Exchange (ETDEWEB)

    Dong, X; Elder, E; Roper, J; Dhabaan, A [Winship Cancer Institute of Emory University (United States)

    2015-06-15

    Purpose: The empirical dual energy calibration (EDEC) method corrects for beam-hardening artifacts, but shows limited performance on metal artifact correction. In this work, we propose an adaptive dual energy calibration (ADEC) method to correct for metal artifacts. Methods: The empirical dual energy calibration (EDEC) method corrects for beam-hardening artifacts, but shows limited performance on metal artifact correction. In this work, we propose an adaptive dual energy calibration (ADEC) method to correct for metal artifacts. Results: Highly attenuating copper rods cause severe streaking artifacts on standard CT images. EDEC improves the image quality, but cannot eliminate the streaking artifacts. Compared to EDEC, the proposed ADEC method further reduces the streaking resulting from metallic inserts and beam-hardening effects and obtains material decomposition images with significantly improved accuracy. Conclusion: We propose an adaptive dual energy calibration method to correct for metal artifacts. ADEC is evaluated with the Shepp-Logan phantom, and shows superior metal artifact correction performance. In the future, we will further evaluate the performance of the proposed method with phantom and patient data.

  16. Artifact free denuder method for sampling of carbonaceous aerosols

    Science.gov (United States)

    Mikuška, P.; Vecera, Z.; Broškovicová, A.

    2003-04-01

    Over the past decade, a growing attention has been focused on the carbonaceous aerosols. Although they may account for 30--60% of the total fine aerosol mass, their concentration and formation mechanisms are not well understood, particularly in comparison with major fine particle inorganic species. The deficiency in knowledge of carbonaceous aerosols results from their complexity and because of problems associated with their collection. Conventional sampling techniques of the carbonaceous aerosols, which utilize filters/backup adsorbents suffer from sampling artefacts. Positive artifacts are mainly due to adsorption of gas-phase organic compounds by the filter material or by the already collected particles, whereas negative artifacts arise from the volatilisation of already collected organic compounds from the filter. Furthermore, in the course of the sampling, the composition of the collected organic compounds may be modified by oxidants (O_3, NO_2, PAN, peroxides) that are present in the air passing through the sampler. It is clear that new, artifact free, method for sampling of carbonaceous aerosols is needed. A combination of a diffusion denuder and a filter in series is very promising in this respect. The denuder is expected to collect gaseous oxidants and gas-phase organic compounds from sample air stream prior to collection of aerosol particles on filters, and eliminate thus both positive and negative sampling artifacts for carbonaceous aerosols. This combination is subject of the presentation. Several designs of diffusion denuders (cylindrical, annular, parallel plate, multi-channel) in combination with various types of wall coatings (dry, liquid) were examined. Special attention was given to preservation of the long-term collection efficiency. Different adsorbents (activated charcoal, molecular sieve, porous polymers) and sorbents coated with various chemical reagents (KI, Na_2SO_3, MnO_2, ascorbic acid) or chromatographic stationary phases (silicon oils

  17. Flexible Capacitive Electrodes for Minimizing Motion Artifacts in Ambulatory Electrocardiograms

    Directory of Open Access Journals (Sweden)

    Jeong Su Lee

    2014-08-01

    Full Text Available This study proposes the use of flexible capacitive electrodes for reducing motion artifacts in a wearable electrocardiogram (ECG device. The capacitive electrodes have conductive foam on their surface, a shield, an optimal input bias resistor, and guarding feedback. The electrodes are integrated in a chest belt, and the acquired signals are transmitted wirelessly for ambulatory heart rate monitoring. We experimentally validated the electrode performance with subjects standing and walking on a treadmill at speeds of up to 7 km/h. The results confirmed the highly accurate heart rate detection capacity of the developed system and its feasibility for daily-life ECG monitoring.

  18. Quantification of motion artifact in ECG electrode design.

    Science.gov (United States)

    Kearney, Kenneth; Thomas, Chris; McAdams, Eric

    2007-01-01

    We have developed a more accurate and reproducible method of quantifying motion artifact in ECG (electrocardiogram) electrodes to assist in electrode assessment and design. It uses an algorithm developed by Sensor Technology & Devices Ltd. to reliably overcome the variation in results due to differing skin types and other causes of spurious readings such as reproducibility of movements used. The method combines a clear, concise experimental protocol with a software package and DSP algorithm to produce a transferable result for one pair of electrodes that can be used for comparison.

  19. Development of an artifact-free aneurysm clip

    Directory of Open Access Journals (Sweden)

    Brack Alexander

    2016-09-01

    Full Text Available For the treatment of intracranial aneurysms with aneurysm clips, usually a follow-up inspection in MRI is required. To avoid any artifacts, which can make a proper diagnosis difficult, a new approach for the manufacturing of an aneurysm clip entirely made from fiber-reinforced plastics has been developed. In this paper the concept for the design of the clip, the development of a new manufacturing technology for the fiber-reinforced components as well as first results from the examination of the components in phantom MRI testing is shown.

  20. Probabilistic expert systems for handling artifacts in complex DNA mixtures.

    Science.gov (United States)

    Cowell, R G; Lauritzen, S L; Mortera, J

    2011-06-01

    This paper presents a coherent probabilistic framework for taking account of allelic dropout, stutter bands and silent alleles when interpreting STR DNA profiles from a mixture sample using peak size information arising from a PCR analysis. This information can be exploited for evaluating the evidential strength for a hypothesis that DNA from a particular person is present in the mixture. It extends an earlier Bayesian network approach that ignored such artifacts. We illustrate the use of the extended network on a published casework example.

  1. Artifacts and pitfalls in shoulder magnetic resonance imaging.

    Science.gov (United States)

    Marcon, Gustavo Felix; Macedo, Tulio Augusto Alves

    2015-01-01

    Magnetic resonance imaging has revolutionized the diagnosis of shoulder lesions, in many cases becoming the method of choice. However, anatomical variations, artifacts and the particularity of the method may be a source of pitfalls, especially for less experienced radiologists. In order to avoid false-positive and false-negative results, the authors carried out a compilation of imaging findings that may simulate injury. It is the authors' intention to provide a useful, consistent and comprehensive reference for both beginner residents and skilled radiologists who work with musculoskeletal magnetic resonance imaging, allowing for them to develop more precise reports and helping them to avoid making mistakes.

  2. The measurement artifact in the Organizational Commitment Questionnaire.

    Science.gov (United States)

    Caught, K; Shadur, M A; Rodwell, J J

    2000-12-01

    This study empirically examined the debate in the literature regarding the dimensionality of the Organizational Commitment Questionnaire. The sample comprised 803 employees from organizations in the information technology and hospitality industries. Confirmatory factor analysis showed that the Organizational Commitment Questionnaire appears to have a two-factor structure, with one factor consisting of positively worded items and the other factor, negatively worded items. Scores on both factors correlated significantly with job satisfaction, suggesting that both factors appear to be measuring a similar aspect of organizational commitment and that they present as two factors given as measurement artifacts of the item wording.

  3. Repair and Reuse of Old and Useless Tubing Rod and Oil Well Pump%废旧油管杆、抽油泵的修复与再利用

    Institute of Scientific and Technical Information of China (English)

    徐旭龙; 马景萍; 李林; 罗琼; 刘学文

    2012-01-01

    According to the example of Zhaoan operation area in No.1 Oil Production Factory of Changqing Oilfield,it is analyzed why there are so large renewal number and high scrappage of tubing rods and oil well pumps in this factory,which account for 3% to 5% of production cost in the whole operation area.Then some suggestions and methods about how to increase the operation rate of old and useless tubing rods and oil well pumps and lower the cost of oil well production are proposed so as to promote the sustainable development of conservation-minded and friendly environmental enterprises construction.%以长庆油田采油一厂招安作业区为例,论述了占整个作业区生产成本费用3%~5%油管杆、抽油泵,更换数量多、报废率高的原因,提出了如何提高旧废油管杆、抽油泵的利用率,降低油井生产成本的建议和方法,从而促进节约型和环境友好型企业建设可持续发展。

  4. Terahertz Absorption by Cellulose: Application to Ancient Paper Artifacts

    Science.gov (United States)

    Peccianti, M.; Fastampa, R.; Mosca Conte, A.; Pulci, O.; Violante, C.; Łojewska, J.; Clerici, M.; Morandotti, R.; Missori, M.

    2017-06-01

    Artifacts made of cellulose, such as ancient documents, pose a significant experimental challenge in the terahertz transmission spectra interpretation due to their small optical thickness. In this paper, we describe a method to recover the complex refractive index of cellulose fibers from the terahertz transmission data obtained on single freely standing paper sheets in the (0.2-3.5)-THz range. By using our technique, we eliminate Fabry-Perot effects and recover the absorption coefficient of the cellulose fibers. The obtained terahertz absorption spectra are explained in terms of absorption peaks of the cellulose crystalline phase superimposed to a background contribution due to a disordered hydrogen-bond network. The comparison between the experimental spectra with terahertz vibrational properties simulated by density-functional-theory calculations confirms this interpretation. In addition, evident changes in the terahertz absorption spectra are produced by natural and artificial aging on paper samples, whose final stage is characterized by a spectral profile with only two peaks at about 2.1 and 3.1 THz. These results can be used to provide a quantitative assessment of the state of preservation of cellulose artifacts.

  5. Optical nano artifact metrics using silicon random nanostructures

    Science.gov (United States)

    Matsumoto, Tsutomu; Yoshida, Naoki; Nishio, Shumpei; Hoga, Morihisa; Ohyagi, Yasuyuki; Tate, Naoya; Naruse, Makoto

    2016-08-01

    Nano-artifact metrics exploit unique physical attributes of nanostructured matter for authentication and clone resistance, which is vitally important in the age of Internet-of-Things where securing identities is critical. However, expensive and huge experimental apparatuses, such as scanning electron microscopy, have been required in the former studies. Herein, we demonstrate an optical approach to characterise the nanoscale-precision signatures of silicon random structures towards realising low-cost and high-value information security technology. Unique and versatile silicon nanostructures are generated via resist collapse phenomena, which contains dimensions that are well below the diffraction limit of light. We exploit the nanoscale precision ability of confocal laser microscopy in the height dimension; our experimental results demonstrate that the vertical precision of measurement is essential in satisfying the performances required for artifact metrics. Furthermore, by using state-of-the-art nanostructuring technology, we experimentally fabricate clones from the genuine devices. We demonstrate that the statistical properties of the genuine and clone devices are successfully exploited, showing that the liveness-detection-type approach, which is widely deployed in biometrics, is valid in artificially-constructed solid-state nanostructures. These findings pave the way for reasonable and yet sufficiently secure novel principles for information security based on silicon random nanostructures and optical technologies.

  6. Effect of membrane filtration artifacts on dissolved trace element concentrations

    Science.gov (United States)

    Horowitz, Arthur J.; Elrick, Kent A.; Colberg, Mark R.

    1992-01-01

    Among environment scientists, the current and almost universally accepted definition of dissolved constituents is an operational one; only those materials which pass through a 0.45-??m membrane filter are considered to be dissolved. Detailed laboratory and field studies on Fe and Al indicate that a number of factors associated with filtration, other than just pore size, can substantially alter 'dissolved' trace element concentrations; these include: filter type, filter diameter, filtration method, volume of sample processed, suspended sediment concentration, suspended sediment grain-size distribution, concentration of colloids and colloidally associated trace elements and concentration of organic matter. As such, reported filtered-water concentrations employing the same pore size filter may not be equal. Filtration artifacts may lead to the production of chemical data that indicate seasonal or annual 'dissolved' chemical trends which do not reflect actual environmental conditions. Further, the development of worldwide averages for various dissolved chemical constituents, the quantification of geochemical cycles, and the determination of short- or long-term environmental chemical trends may be subject to substantial errors, due to filtration artifacts, when data from the same or multiple sources are combined. Finally, filtration effects could have a substantial impact on various regulatory requirements.

  7. Optical nano artifact metrics using silicon random nanostructures

    Science.gov (United States)

    Matsumoto, Tsutomu; Yoshida, Naoki; Nishio, Shumpei; Hoga, Morihisa; Ohyagi, Yasuyuki; Tate, Naoya; Naruse, Makoto

    2016-01-01

    Nano-artifact metrics exploit unique physical attributes of nanostructured matter for authentication and clone resistance, which is vitally important in the age of Internet-of-Things where securing identities is critical. However, expensive and huge experimental apparatuses, such as scanning electron microscopy, have been required in the former studies. Herein, we demonstrate an optical approach to characterise the nanoscale-precision signatures of silicon random structures towards realising low-cost and high-value information security technology. Unique and versatile silicon nanostructures are generated via resist collapse phenomena, which contains dimensions that are well below the diffraction limit of light. We exploit the nanoscale precision ability of confocal laser microscopy in the height dimension; our experimental results demonstrate that the vertical precision of measurement is essential in satisfying the performances required for artifact metrics. Furthermore, by using state-of-the-art nanostructuring technology, we experimentally fabricate clones from the genuine devices. We demonstrate that the statistical properties of the genuine and clone devices are successfully exploited, showing that the liveness-detection-type approach, which is widely deployed in biometrics, is valid in artificially-constructed solid-state nanostructures. These findings pave the way for reasonable and yet sufficiently secure novel principles for information security based on silicon random nanostructures and optical technologies. PMID:27578146

  8. Racial IQ Differences among Transracial Adoptees: Fact or Artifact?

    Directory of Open Access Journals (Sweden)

    Drew Thomas

    2016-12-01

    Full Text Available Some academic publications infer from studies of transracial adoptees’ IQs that East Asian adoptees raised in the West by Whites have higher IQs than Western Whites, and that White adoptees raised by Whites have higher IQs than Black adoptees raised by Whites. Those publications suggest that this is because genetic differences give East Asians a higher mean IQ than Whites, and Whites a higher mean IQ than Blacks. This paper proposes a parsimonious alternative explanation: the apparent IQ advantage of East Asian adoptees is an artifact caused by ignoring the Flynn effect and adoption’s beneficial effect on IQ, and most of the IQ disadvantage of Black adoptees disappears when one allows for attrition in the Minnesota Transracial Adoption Study, and acknowledges the results of other studies. Diagnosing these artifacts suggests a nil hypothesis: East Asian, White, and Black adoptees raised in the same environment would have similar IQs, hinting at a minimal role for genes in racial IQ differences.

  9. Prospectively ECG Gated CT pulmonary angiography versus helical ungated CT pulmonary angiography: Impact on cardiac related motion artifacts and patient radiation dose

    Energy Technology Data Exchange (ETDEWEB)

    Shuman, William P., E-mail: wshuman@u.washington.edu [Department of Radiology, 1959 NE Pacific Street, Box 357115, Seattle, WA 98195 (United States); Leipsic, Jonathon A., E-mail: JLeipsic@providencehealth.bc.ca [University of British Columbia and St. Paul' s Hospital, Department of Radiology, 1081 Burrard Street, Vancouver, BC, V6Z1Y6 (Canada); Busey, Janet M., E-mail: jbonny@u.washington.edu [Department of Radiology, 1959 NE Pacific Street, Box 357115, Seattle, WA 98195 (United States); Green, Douglas E., E-mail: dougreen@uw.edu [Department of Radiology, 1959 NE Pacific Street, Box 357115, Seattle, WA 98195 (United States); Pipavath, Sudhakar N., E-mail: snjp@u.wwashington.edu [Department of Radiology, 1959 NE Pacific Street, Box 357115, Seattle, WA 98195 (United States); Hague, Cameron J., E-mail: cjhague@interchange.ubc.ca [University of British Columbia and St. Paul' s Hospital, Department of Radiology, 1081 Burrard Street, Vancouver, BC, V6Z1Y6 (Canada); Koprowicz, Kent M., E-mail: kentk@u.washington.edu [Department of Radiology, 1959 NE Pacific Street, Box 357115, Seattle, WA 98195 (United States)

    2012-09-15

    Objective: To compare prospectively ECG gated CT pulmonary angiography (CTPA) with routine helical ungated CTPA for cardiac related motion artifacts and patient radiation dose. Subjects and methods: Twenty patients with signs and symptoms suspicious for pulmonary embolism and who had a heart rate below 85 were scanned with prospectively ECG gated CTPA. These gated exams were matched for several clinical parameters to exams from twenty similar clinical patients scanned with routine ungated helical CTPA. Three blinded independent reviewers subjectively evaluated all exams for overall pulmonary artery enhancement and for several cardiac motion related artifacts, including vessel blurring, intravascular shading, and double line. Reviewers also measured pulmonary artery intravascular density and image noise. Patient radiation dose for each technique was compared. Fourteen clinical prospectively ECG gated CTPA exams from a second institution were evaluated for the same parameters. Results: Prospectively ECG gated CTPA resulted in significantly decreased motion-related image artifact scores in lung segments adjacent to the heart compared to ungated CTPA. Measured image noise was not significantly different between the two types of CTPA exams. Effective dose was 28% less for prospectively ECG gated CTPA (4.9 mSv versus 6.8 mSv, p = 0.02). Similar results were found in the prospectively ECG gated exams from the second institution. Conclusion: Compared to routine helical ungated CTPA, prospectively ECG gated CTPA may result in less cardiac related motion artifact in lung segments adjacent to the heart and significantly less patient radiation dose.

  10. Classical realization of dispersion-canceled, artifact-free, and background-free optical coherence tomography

    CERN Document Server

    Ogawa, Kazuhisa

    2016-01-01

    Quantum-optical coherence tomography (Q-OCT) provides a dispersion-canceled axial-imaging method, but its practical use is limited by the weakness of the light source and by artifacts in the images. A recent study using chirped-pulse interferometry (CPI) has demonstrated dispersion-canceled and artifact-free OCT with a classical system; however, unwanted background signals still remain after removing the artifacts. Here, we propose a classical optical method that realizes dispersion-canceled, artifact-free, and background-free OCT. We employ a time-reversed system for Q-OCT with transform-limited input laser pulses to achieve dispersion-canceled OCT with a classical system. We have also introduced a subtraction method to remove artifacts and background signals. With these methods, we experimentally demonstrated dispersion-canceled, artifact-free, and background-free axial imaging of a coverglass and cross-sectional imaging of the surface of a coin.

  11. A dialectical take on artifact ecologies and the physical - digital divide

    DEFF Research Database (Denmark)

    Bødker, Susanne; Klokmose, Clemens Nylandsted

    In this position paper, we will present and discuss our understanding of artifact ecologies as we have developed it, rooted in activity theoretical HCI and dialectical thinking . Our basis is in the Human-Artifact Model, as well as well as cases where we have worked with artifact ecologies...... in analysis and design of computer mediated activity. The paper concludes with a positioning of our perspective vis-a-vis the notions of natural and blended interaction and the physical-digital divide...

  12. Political and socioeconomic implications of Classic Maya lithic artifacts from the Main Plaza of Aguateca, Guatemala

    OpenAIRE

    AOYAMA, Kazuo

    2014-01-01

    Political and socioeconomic implications of Classic Maya lithic artifacts from the Main Plaza of Aguateca, Guatemala. This article discusses the results of an analysis of 4,076 lithic artifacts collected in and around the Main Plaza of Aguateca, Guatemala, by the Aguateca Restoration Project Second Phase with the objective of examining Classic Maya political and socioeconomic organization. First, combined with the results of analysis of 10,845 lithic artifacts collected in the Palace Group, t...

  13. Physiologic artifacts in resting state oscillations in young children: methodological considerations for noisy data.

    Science.gov (United States)

    McEvoy, Kevin; Hasenstab, Kyle; Senturk, Damla; Sanders, Andrew; Jeste, Shafali S

    2015-03-01

    We quantified the potential effects of physiologic artifact on the estimation of EEG band power in a cohort of typically developing children in order to guide artifact rejection methods in quantitative EEG data analysis in developmental populations. High density EEG was recorded for 2 min while children, ages 2-6, watched a video of bubbles. Segments of data were categorized as blinks, saccades, EMG or artifact-free, and both absolute and relative power in the theta (4-7 Hz), alpha (8-12 Hz), beta (13-30 Hz) and gamma (35-45 Hz) bands were calculated in 9 regions for each category. Using a linear mixed model approach with artifact type, region and their interaction as predictors, we compared mean band power between clean data and each type of artifact. We found significant differences in mean relative and absolute power between artifacts and artifact-free segments in all frequency bands. The magnitude and direction of the differences varied based on power type, region, and frequency band. The most significant differences in mean band power were found in the gamma band for EMG artifact and the theta band for ocular artifacts. Artifact detection strategies need to be sensitive to the oscillations of interest for a given analysis, with the most conservative approach being the removal of all EMG and ocular artifact from EEG data. Quantitative EEG holds considerable promise as a clinical biomarker of both typical and atypical development. However, there needs to be transparency in the choice of power type, regions of interest, and frequency band, as each of these variables are differentially vulnerable to noise, and therefore, their interpretation depends on the methods used to identify and remove artifacts.

  14. Reduction of skin stretch induced motion artifacts in electrocardiogram monitoring using adaptive filtering.

    Science.gov (United States)

    Liu, Yan; Pecht, Michael G

    2006-01-01

    The effectiveness of electrocardiogram (ECG) monitors can be significantly impaired by motion artifacts which can cause misdiagnoses, lead to inappropriate treatment decisions, and trigger false alarms. Skin stretch associated with patient motion is a significant source of motion artifacts in current ECG monitoring. In this study, motion artifacts are adaptively filtered by using skin strain as the reference variable. Skin strain is measured non-invasively using a light emitting diode (LED) and an optical sensor incorporated in an ECG electrode. The results demonstrate that this device and method can significantly reduce skin strain induced ECG artifacts.

  15. Reduction of motion artifacts in electrocardiogram monitoring using an optical sensor.

    Science.gov (United States)

    Liu, Yan; Pecht, Michael G

    2011-01-01

    The effectiveness of electrocardiogram (ECG) monitors can be significantly impaired by motion artifacts, which can trigger false alarms, cause misdiagnoses, and lead to inappropriate treatment decisions. Skin stretch associated with patient motion is the most significant source of motion artifacts in current ECG monitoring. In this study, motion artifacts are adaptively filtered by using skin strain as the reference variable, measured noninvasively using an optical sensor incorporated into an ECG electrode. The results demonstrate that this new device and method can significantly reduce motion induced ECG artifacts in continuous ambulatory ECG monitoring.

  16. An Unusual Cause of the Ring Artifact on Transaxial CT Images.

    Science.gov (United States)

    Jha, Ashish Kumar; Purandare, Nilendu C; Rangarajan, Venkatesh

    2016-09-01

    Artifacts and image quality are two sides of the same coin. The ring artifact is scanner-based and caused mainly by either a miscalibrated element or a defective element of a detector row. We describe a rare cause of the ring artifact that appeared on a transaxial CT image because of a loose electronic contact. To our knowledge, this particular cause of the ring artifact has not been described in literature. © 2016 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

  17. A platform-independent method to reduce CT truncation artifacts using discriminative dictionary representations.

    Science.gov (United States)

    Chen, Yang; Budde, Adam; Li, Ke; Li, Yinsheng; Hsieh, Jiang; Chen, Guang-Hong

    2017-01-01

    When the scan field of view (SFOV) of a CT system is not large enough to enclose the entire cross-section of the patient, or the patient needs to be positioned partially outside the SFOV for certain clinical applications, truncation artifacts often appear in the reconstructed CT images. Many truncation artifact correction methods perform extrapolations of the truncated projection data based on certain a priori assumptions. The purpose of this work was to develop a novel CT truncation artifact reduction method that directly operates on DICOM images. The blooming of pixel values associated with truncation was modeled using exponential decay functions, and based on this model, a discriminative dictionary was constructed to represent truncation artifacts and nonartifact image information in a mutually exclusive way. The discriminative dictionary consists of a truncation artifact subdictionary and a nonartifact subdictionary. The truncation artifact subdictionary contains 1000 atoms with different decay parameters, while the nonartifact subdictionary contains 1000 independent realizations of Gaussian white noise that are exclusive with the artifact features. By sparsely representing an artifact-contaminated CT image with this discriminative dictionary, the image was separated into a truncation artifact-dominated image and a complementary image with reduced truncation artifacts. The artifact-dominated image was then subtracted from the original image with an appropriate weighting coefficient to generate the final image with reduced artifacts. This proposed method was validated via physical phantom studies and retrospective human subject studies. Quantitative image evaluation metrics including the relative root-mean-square error (rRMSE) and the universal image quality index (UQI) were used to quantify the performance of the algorithm. For both phantom and human subject studies, truncation artifacts at the peripheral region of the SFOV were effectively reduced, revealing

  18. Reduction of truncation artifacts in CT images via a discriminative dictionary representation method

    Science.gov (United States)

    Chen, Yang; Li, Ke; Li, Yinsheng; Hsieh, Jiang; Chen, Guang-Hong

    2016-04-01

    When the scan field of view (SFOV) of a CT system is not large enough to enclose the entire cross-section of a patient, or the patient needs to be intentionally positioned partially outside the SFOV for certain clinical CT scans, truncation artifacts are often observed in the reconstructed CT images. Conventional wisdom to reduce truncation artifacts is to complete the truncated projection data via data extrapolation with different a priori assumptions. This paper presents a novel truncation artifact reduction method that directly works in the CT image domain. Specifically, a discriminative dictionary that includes a sub-dictionary of truncation artifacts and a sub-dictionary of non-artifact image information was used to separate a truncation artifact-contaminated image into two sub-images, one with reduced truncation artifacts, and the other one containing only the truncation artifacts. Both experimental phantom and retrospective human subject studies have been performed to characterize the performance of the proposed truncation artifact reduction method.

  19. Brain-in-Brain Artifact (BIBA) in a Patient with Hydranencepaly: A Case Report

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Sang Young; Kim, You Me; Lee, Seung Ha; Lee, Young Seok [College of Medicine Dankook University Hospital, Cheonan (Korea, Republic of)

    2011-03-15

    Hydranencephaly is a condition that is characterized by an absent brain mantle along with the subadjacent white matter, with replacement of the cerebral hemispheres by a thin-walled membranous sac containing CSF. During brain sonograpy in a neonate with hydranencephaly, we have found a brain-in-brain appearance as an unusual sonographic artifact. We report here on this interesting sonographic artifact in a neonate with hydranencephaly, and this artifact was due to multipath reflection artifact of the ultrasound beam/wave, and we explain the underlying physics

  20. Beyond Relevance: In Praise of Useless Knowledge

    Science.gov (United States)

    Ikpe, I. B.

    2010-01-01

    The influence of positivism in education has been on the increase in the recent past, with academic departments increasingly being asked to justify the money spent on them and show some level of cost effectiveness. There is no other cluster of academic disciplines that is adversely affected by new wave of positivism as the Humanities which is…

  1. Impure placebo is a useless concept.

    Science.gov (United States)

    Louhiala, Pekka; Hemilä, Harri; Puustinen, Raimo

    2015-08-01

    Placebos are allegedly used widely in general practice. Surveys reporting high level usage, however, have combined two categories, 'pure' and 'impure' placebos. The wide use of placebos is explained by the high level usage of impure placebos. In contrast, the prevalence of the use of pure placebos has been low. Traditional pure placebos are clinically ineffective treatments, whereas impure placebos form an ambiguous group of diverse treatments that are not always ineffective. In this paper, we focus on the impure placebo concept and demonstrate problems related to it. We also show that the common examples of impure placebos are not meaningful from the point of view of clinical practice. We conclude that the impure placebo is a scientifically misleading concept and should not be used in scientific or medical literature. The issues behind the concept, however, deserve serious attention in future research.

  2. Resistance is useless the lure of superconductors

    CERN Multimedia

    Ingham, R

    2003-01-01

    The 2003 Nobel Physics Prize has been awarded to quantum researchers, Alexei A. Abrikosov and Vitaly L. Ginzburg for their work on superconductivity. The pair share the award with a British-born American, Anthony J. Leggett, for his research into superfluidity (1/2 page).

  3. 脊柱侧弯畸形MRI检查出现伪影的诊断及鉴别%Scoliosis MRI examination diagnosis and differential of artifacts

    Institute of Scientific and Technical Information of China (English)

    王宝春; 杨献峰; 周晓秋

    2015-01-01

    目的:探讨脊柱侧弯畸形患者MRI检查时横轴位T2WI相中出现的伪影与脊髓纵裂畸形的诊断及鉴别诊断。方法:回顾分析经手术证实的44例脊柱侧弯畸形患者横轴位T2WI相出现的伪影。结果:44例出现T2WI图像伪影的患者,均发生于脊柱侧弯处。其中,6例纵裂伪影均位于胸段脊髓;26例车轮状伪影中24例位于胸段脊髓,2例位于第1腰椎水平段;12例同时出现纵裂伪影及车轮状伪影。纵裂伪影T2WI部分高信号影形态欠规则。车轮状伪影T2WI相表现髓内及椎管内多个裂隙样辐射状高信号。结论:脊柱侧弯患者在MRI检查时T2WI相侧弯处易出现纵裂畸形伪影,应结合MRI多序列、多参数成像进行鉴别,减少误诊。%Objective:To investigate the artifacts on T2MI phase in MRI examination of patients of scoliosis and deformity of cleft and diagnosis and differential diagnosis of diastematomyelia malformation. Methods:To retrospec-tively analyze the artifacts on axial T2WI phase of 44 patients of scoliosis who were confirmed by operation. Results:All the artifacts occurred in the bend of spinal column side in all 44patients.In these patients,6 cases of diastematomyelia artifacts were located in the thoracic spinal cord, and 24 cases in 26 cases of the wheel shaped artifacts were located in the thoracic spinal cord,2 cases of which were located in the first lumbar vertebra level, and diastematomyelia artifacts and wheel shaped artifacts occurred in 12 cases at the same time. Diastematomyelia artifacts appeared as thready and high signals in spinal cord on T2WI phase, some lines of high signals of which appeared in irregular shape. The wheel shaped artifacts appeared as many stenopaic and radial artifacts on T 2W I phase in spinal cord and spinal canal. Conclusion:It is easy to appear diastematomyelia artifacts at the slide bend on T 2WI phase in MRI examination in pa-tients with scoliosis, so we should make

  4. L'utilità dell'apparentemente inutile. La casa per un uccello, un aquilone, un gioco / The usefulness of what seems useless. Project-Design for a bird house, a kite and a game

    Directory of Open Access Journals (Sweden)

    Gustavo Adolfo Carabajal

    2014-03-01

    Full Text Available The workshop experience becomes an occasion to address the theme of the usefulness of what seems useless: What is obtained in dealing with the design issues of building a bird house, a kite or a game? An investigation is set forth regarding the techniques of a project-design and its representation, with the objective of enhancing one’s knowledge about the essential aspects of the architect’s work: how to begin, how is the process of design developed, how and what information is to be obtained, the issue of scale, the role of structure, materials, the natural elements, and the environmental components that are specific to a place. These exercises become the place for a collection of materials that can make up an un-writable encyclopedia of inspired knowledge, imagination, and even the satisfactory decisions in the true story they tell. / L’esperienza dei workshop diventa occasione per frequentare l’argomento dell’utilità dell’apparentemente inutile: Cosa si ottiene affrontando i problemi del progetto di una casa per un uccello, un aquilone o un gioco? Si avvia un’indagine sulle tecniche del progetto e sulla sua rappresentazione, con l'obiettivo di approfondire gli aspetti essenziali del lavoro dell'architetto: come si inizia, come avviene il processo di ideazione, il modo di documentarsi, il tema della scala, il ruolo della struttura, i materiali, gli elementi naturali e le componenti ambientali specifiche di un luogo. Questi esercizi sono il luogo della collezione dei materiali per una enciclopedia non scrivibile dell'ispirazione, dell'immaginazione o addirittura delle decisioni felici delle quali parlano.

  5. Clinical evaluation of TOF versus non-TOF on PET artifacts in simultaneous PET/MR: a dual centre experience.

    Science.gov (United States)

    Ter Voert, Edwin E G W; Veit-Haibach, Patrick; Ahn, Sangtae; Wiesinger, Florian; Khalighi, M Mehdi; Levin, Craig S; Iagaru, Andrei H; Zaharchuk, Greg; Huellner, Martin; Delso, Gaspar

    2017-07-01

    Our objective was to determine clinically the value of time-of-flight (TOF) information in reducing PET artifacts and improving PET image quality and accuracy in simultaneous TOF PET/MR scanning. A total 65 patients who underwent a comparative scan in a simultaneous TOF PET/MR scanner were included. TOF and non-TOF PET images were reconstructed, clinically examined, compared and scored. PET imaging artifacts were categorized as large or small implant-related artifacts, as dental implant-related artifacts, and as implant-unrelated artifacts. Differences in image quality, especially those related to (implant) artifacts, were assessed using a scale ranging from 0 (no artifact) to 4 (severe artifact). A total of 87 image artifacts were found and evaluated. Four patients had large and eight patients small implant-related artifacts, 27 patients had dental implants/fillings, and 48 patients had implant-unrelated artifacts. The average score was 1.14 ± 0.82 for non-TOF PET images and 0.53 ± 0.66 for TOF images (p < 0.01) indicating that artifacts were less noticeable when TOF information was included. Our study indicates that PET image artifacts are significantly mitigated with integration of TOF information in simultaneous PET/MR. The impact is predominantly seen in patients with significant artifacts due to metal implants.

  6. Clinical evaluation of TOF versus non-TOF on PET artifacts in simultaneous PET/MR: a dual centre experience

    Energy Technology Data Exchange (ETDEWEB)

    Voert, Edwin E.G.W. ter [University Hospital Zurich, Department of Nuclear Medicine, Zurich (Switzerland); University of Zurich, Zurich (Switzerland); Veit-Haibach, Patrick [University Hospital Zurich, Department of Nuclear Medicine, Zurich (Switzerland); University of Zurich, Zurich (Switzerland); University Hospital Zurich, Department of Diagnostic and Interventional Radiology, Zurich (Switzerland); Ahn, Sangtae [GE Global Research, Niskayuna, NY (United States); Wiesinger, Florian [GE Global Research, Muenchen (Germany); Khalighi, M.M.; Delso, Gaspar [GE Healthcare, Waukesha, WI (United States); Levin, Craig S. [Stanford University, Department of Radiology, Molecular Imaging Program at Stanford, Stanford, CA (United States); Iagaru, Andrei H. [Stanford University, Department of Radiology, Division of Nuclear Medicine and Molecular Imaging, Stanford, CA (United States); Zaharchuk, Greg [Stanford University, Department of Radiology, Neuroradiology, Stanford, CA (United States); Huellner, Martin [University Hospital Zurich, Department of Nuclear Medicine, Zurich (Switzerland); University of Zurich, Zurich (Switzerland); University Hospital Zurich, Department of Neuroradiology, Zurich (Switzerland)

    2017-07-15

    Our objective was to determine clinically the value of time-of-flight (TOF) information in reducing PET artifacts and improving PET image quality and accuracy in simultaneous TOF PET/MR scanning. A total 65 patients who underwent a comparative scan in a simultaneous TOF PET/MR scanner were included. TOF and non-TOF PET images were reconstructed, clinically examined, compared and scored. PET imaging artifacts were categorized as large or small implant-related artifacts, as dental implant-related artifacts, and as implant-unrelated artifacts. Differences in image quality, especially those related to (implant) artifacts, were assessed using a scale ranging from 0 (no artifact) to 4 (severe artifact). A total of 87 image artifacts were found and evaluated. Four patients had large and eight patients small implant-related artifacts, 27 patients had dental implants/fillings, and 48 patients had implant-unrelated artifacts. The average score was 1.14 ± 0.82 for non-TOF PET images and 0.53 ± 0.66 for TOF images (p < 0.01) indicating that artifacts were less noticeable when TOF information was included. Our study indicates that PET image artifacts are significantly mitigated with integration of TOF information in simultaneous PET/MR. The impact is predominantly seen in patients with significant artifacts due to metal implants. (orig.)

  7. Big Data between audiovisual displays, artifacts, and aesthetic experience

    DEFF Research Database (Denmark)

    Bjørnsten, Thomas

    2016-01-01

    of large data sets – or Big Data – into the sphere of art and the aesthetic. Central to the discussion here is the analysis of how different structuring principles of data and the discourses that surround these principles shape our perception of data. This discussion involves considerations on various......This article discusses artistic practices and artifacts that are occupied with exploring data through visualization and sonification strategies as well as with translating data into materially solid formats and embodied processes. By means of these examples the overall aim of the article...... is to critically question how and whether such artistic practices can eventually lead to the experience and production of knowledge that could not otherwise be obtained via more traditional ways of data representation. The article, thus, addresses both the problems and possibilities entailed in extending the use...

  8. A Model for Geometry-Dependent Errors in Length Artifacts.

    Science.gov (United States)

    Sawyer, Daniel; Parry, Brian; Phillips, Steven; Blackburn, Chris; Muralikrishnan, Bala

    2012-01-01

    We present a detailed model of dimensional changes in long length artifacts, such as step gauges and ball bars, due to bending under gravity. The comprehensive model is based on evaluation of the gauge points relative to the neutral bending surface. It yields the errors observed when the gauge points are located off the neutral bending surface of a bar or rod but also reveals the significant error associated with out-of-straightness of a bar or rod even if the gauge points are located in the neutral bending surface. For example, one experimental result shows a length change of greater than 1.5 µm on a 1 m ball bar with an out-of-straightness of 0.4 mm. This and other results are in agreement with the model presented in this paper.

  9. Trail Trees: Living Artifacts (Vivifacts of Eastern North America

    Directory of Open Access Journals (Sweden)

    Nicholas C. Kawa

    2015-09-01

    Full Text Available Living trees historically modified by human populations, oftentimes referred to as “culturally modified trees” (CMTs, are found throughout the North American landscape. In eastern North America specifically, indigenous populations bent thousands of trees to mark trails, and some of these still exist in the region today. In this article, we present a synthesis of current knowledge on trail trees, including their speculated functions, formation, and selection. We also examine the theoretical implications of these living artifacts (or vivifacts and how they may open new avenues for investigation by archaeologists, environmental historians, and ethnobiologists. To conclude, we make a call for expanded public recognition and documentation of trail trees, discussing the need for their incorporation into forest and park management plans.

  10. Wireless Accelerometer for Neonatal MRI Motion Artifact Correction

    Directory of Open Access Journals (Sweden)

    Martyn Paley

    2017-01-01

    Full Text Available A wireless accelerometer has been used in conjunction with a dedicated 3T neonatal MRI system installed on a Neonatal Intensive Care Unit to measure in-plane rotation which is a common problem with neonatal MRI. Rotational data has been acquired in real-time from phantoms simultaneously with MR images which shows that the wireless accelerometer can be used in close proximity to the MR system. No artifacts were observed on the MR images from the accelerometer or from the MR system on the accelerometer output. Initial attempts to correct the raw data using the measured rotational angles have been performed, but further work will be required to make a robust correction algorithm.

  11. Big Data between audiovisual displays, artifacts, and aesthetic experience

    DEFF Research Database (Denmark)

    Bjørnsten, Thomas

    2016-01-01

    of large data sets – or Big Data – into the sphere of art and the aesthetic. Central to the discussion here is the analysis of how different structuring principles of data and the discourses that surround these principles shape our perception of data. This discussion involves considerations on various......This article discusses artistic practices and artifacts that are occupied with exploring data through visualization and sonification strategies as well as with translating data into materially solid formats and embodied processes. By means of these examples the overall aim of the article...... is to critically question how and whether such artistic practices can eventually lead to the experience and production of knowledge that could not otherwise be obtained via more traditional ways of data representation. The article, thus, addresses both the problems and possibilities entailed in extending the use...

  12. Crime scene ethics: souvenirs, teaching material, and artifacts.

    Science.gov (United States)

    Rogers, Tracy L

    2004-03-01

    Police and forensic specialists are ethically obliged to preserve the integrity of their investigations and their agencies' reputations. The American Academy of Forensic Sciences and the Canadian Society of Forensic Science provide no guidelines for crime scene ethics, or the retention of items from former crime scenes. Guidelines are necessary to define acceptable behavior relating to removing, keeping, or selling artifacts, souvenirs, or teaching specimens from former crime scenes, where such activities are not illegal, to prevent potential conflicts of interest and the appearance of impropriety. Proposed guidelines permit the retention of objects with educational value, provided they are not of significance to the case, they are not removed until the scene is released, permission has been obtained from the property owner and police investigator, and the item has no significant monetary value. Permission is necessary even if objects appear discarded, or are not typically regarded as property, e.g., animal bones.

  13. Artifacts in spectral-domain optical coherence tomography measurements in glaucoma.

    Science.gov (United States)

    Asrani, Sanjay; Essaid, Luma; Alder, Brian D; Santiago-Turla, Cecilia

    2014-04-01

    IMPORTANCE Spectral-domain optical coherence tomography (SD-OCT) has an integral role in the diagnosis and treatment of glaucoma. Understanding the types of artifacts commonly seen in the imaging of patients being evaluated for glaucoma will help physicians better implement these data in the care of patients. OBJECTIVES To determine the frequency and distribution of SD-OCT imaging artifacts in patients being evaluated for glaucoma and to provide examples of common artifacts. DESIGN, SETTING, AND PARTICIPANTS A retrospective cross-sectional study design was used to examine SD-OCT images (using Spectralis SD-OCT) of 277 consecutive patients who had a diagnosis of glaucoma of any stage or had suspected glaucoma. Retinal nerve fiber layer (RNFL) and macular thickness scans were included. For each scan, the final printout and the source images that generated the final printout were examined. If present, artifacts were classified as evident on the final printout or not and were categorized as to the primary source of the artifact (eg, ocular pathologic features or technician errors). Examples of common artifacts are provided. MAIN OUTCOMES AND MEASURES The presence of imaging artifacts. RESULTS In 277 consecutive patients, 131 macular thickness scans were obtained, and 277 RNFL scans were obtained. Of the macular thickness scans, 37 (28.2%; 95% CI, 20.8%-36.1%) had imaging artifacts. Six of these artifacts were not obvious on the final printout. Of the RNFL scans, 55 (19.9%; 95% CI, 15.2%-24.6%) contained artifacts. Seven of these artifacts were not evident on the final printout. The most common cause of artifacts for macular thickness and RNFL scans was ocular pathologic features, primarily the presence of an epiretinal membrane. CONCLUSIONS AND RELEVANCE It is likely that SD-OCT-related imaging artifacts occur in 15.2% to 36.1% of scans obtained in patients being evaluated for glaucoma. Some of these artifacts may not be evident on the final printout. Physicians should

  14. Thematic knowledge, artifact concepts, and the left posterior temporal lobe: Where action and object semantics converge.

    Science.gov (United States)

    Kalénine, Solène; Buxbaum, Laurel J

    2016-09-01

    Converging evidence supports the existence of functionally and neuroanatomically distinct taxonomic (similarity-based; e.g., hammer-screwdriver) and thematic (event-based; e.g., hammer-nail) semantic systems. Processing of thematic relations between objects has been shown to selectively recruit the left posterior temporoparietal cortex. Similar posterior regions have also been shown to be critical for knowledge of relationships between actions and manipulable human-made objects (artifacts). Based on the hypothesis that thematic relationships for artifacts rely, at least in part, on action relationships, we assessed the prediction that the same regions of the left posterior temporoparietal cortex would be critical for conceptual processing of artifact-related actions and thematic relations for artifacts. To test this hypothesis, we evaluated processing of taxonomic and thematic relations for artifacts and natural objects as well as artifact action knowledge (gesture recognition) abilities in a large sample of 48 stroke patients with a range of lesion foci in the left hemisphere. Like control participants, patients identified thematic relations faster than taxonomic relations for artifacts, whereas they identified taxonomic relations faster than thematic relations for natural objects. Moreover, response times (RTs) for identifying thematic relations for artifacts selectively predicted performance in gesture recognition. Whole brain Voxel-based Lesion-Symptom Mapping (VLSM) analyses and Region of Interest (ROI) regression analyses further demonstrated that lesions to the left posterior temporal cortex, overlapping with LTO and visual motion area hMT+, were associated both with relatively slower RTs in identifying thematic relations for artifacts and poorer artifact action knowledge in patients. These findings provide novel insights into the functional role of left posterior temporal cortex in thematic knowledge, and suggest that the close association between thematic

  15. Psycho-physiological effects of visual artifacts by stereoscopic display systems

    Science.gov (United States)

    Kim, Sanghyun; Yoshitake, Junki; Morikawa, Hiroyuki; Kawai, Takashi; Yamada, Osamu; Iguchi, Akihiko

    2011-03-01

    The methods available for delivering stereoscopic (3D) display using glasses can be classified as time-multiplexing and spatial-multiplexing. With both methods, intrinsic visual artifacts result from the generation of the 3D image pair on a flat panel display device. In the case of the time-multiplexing method, an observer perceives three artifacts: flicker, the Mach-Dvorak effect, and a phantom array. These only occur under certain conditions, with flicker appearing in any conditions, the Mach-Dvorak effect during smooth pursuit eye movements (SPM), and a phantom array during saccadic eye movements (saccade). With spatial-multiplexing, the artifacts are temporal-parallax (due to the interlaced video signal), binocular rivalry, and reduced spatial resolution. These artifacts are considered one of the major impediments to the safety and comfort of 3D display users. In this study, the implications of the artifacts for the safety and comfort are evaluated by examining the psychological changes they cause through subjective symptoms of fatigue and the depth sensation. Physiological changes are also measured as objective responses based on analysis of heart and brain activation by visual artifacts. Further, to understand the characteristics of each artifact and the combined effects of the artifacts, four experimental conditions are developed and tested. The results show that perception of artifacts differs according to the visual environment and the display method. Furthermore visual fatigue and the depth sensation are influenced by the individual characteristics of each artifact. Similarly, heart rate variability and regional cerebral oxygenation changes by perception of artifacts in conditions.

  16. Optimizing complexity measures for FMRI data: algorithm, artifact, and sensitivity.

    Directory of Open Access Journals (Sweden)

    Denis Rubin

    Full Text Available INTRODUCTION: Complexity in the brain has been well-documented at both neuronal and hemodynamic scales, with increasing evidence supporting its use in sensitively differentiating between mental states and disorders. However, application of complexity measures to fMRI time-series, which are short, sparse, and have low signal/noise, requires careful modality-specific optimization. METHODS: HERE WE USE BOTH SIMULATED AND REAL DATA TO ADDRESS TWO FUNDAMENTAL ISSUES: choice of algorithm and degree/type of signal processing. Methods were evaluated with regard to resilience to acquisition artifacts common to fMRI as well as detection sensitivity. Detection sensitivity was quantified in terms of grey-white matter contrast and overlap with activation. We additionally investigated the variation of complexity with activation and emotional content, optimal task length, and the degree to which results scaled with scanner using the same paradigm with two 3T magnets made by different manufacturers. Methods for evaluating complexity were: power spectrum, structure function, wavelet decomposition, second derivative, rescaled range, Higuchi's estimate of fractal dimension, aggregated variance, and detrended fluctuation analysis. To permit direct comparison across methods, all results were normalized to Hurst exponents. RESULTS: Power-spectrum, Higuchi's fractal dimension, and generalized Hurst exponent based estimates were most successful by all criteria; the poorest-performing measures were wavelet, detrended fluctuation analysis, aggregated variance, and rescaled range. CONCLUSIONS: Functional MRI data have artifacts that interact with complexity calculations in nontrivially distinct ways compared to other physiological data (such as EKG, EEG for which these measures are typically used. Our results clearly demonstrate that decisions regarding choice of algorithm, signal processing, time-series length, and scanner have a significant impact on the reliability and

  17. Investigation of a potential HCHO measurement artifact from ISOPOOH

    Science.gov (United States)

    St. Clair, Jason M.; Rivera-Rios, Jean C.; Crounse, John D.; Praske, Eric; Kim, Michelle J.; Wolfe, Glenn M.; Keutsch, Frank N.; Wennberg, Paul O.; Hanisco, Thomas F.

    2016-09-01

    Recent laboratory experiments have shown that a first generation isoprene oxidation product, ISOPOOH, can decompose to methyl vinyl ketone (MVK) and methacrolein (MACR) on instrument surfaces, leading to overestimates of MVK and MACR concentrations. Formaldehyde (HCHO) was suggested as a decomposition co-product, raising concern that in situ HCHO measurements may also be affected by an ISOPOOH interference. The HCHO measurement artifact from ISOPOOH for the NASA In Situ Airborne Formaldehyde instrument (ISAF) was investigated for the two major ISOPOOH isomers, (1,2)-ISOPOOH and (4,3)-ISOPOOH, under dry and humid conditions. The dry conversion of ISOPOOH to HCHO was 3 ± 2 % and 6 ± 4 % for (1,2)-ISOPOOH and (4,3)-ISOPOOH, respectively. Under humid (relative humidity of 40-60 %) conditions, conversion to HCHO was 6 ± 4 % for (1,2)-ISOPOOH and 10 ± 5 % for (4,3)-ISOPOOH. The measurement artifact caused by conversion of ISOPOOH to HCHO in the ISAF instrument was estimated for data obtained on the 6 September 2013 flight of the Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) campaign. Prompt ISOPOOH conversion to HCHO was the source of < 4 % of the observed HCHO, including in the high-isoprene boundary layer. Time-delayed conversion, where previous exposure to ISOPOOH affects measured HCHO later in the flight, was conservatively estimated to be < 10 % of observed HCHO, and is significant only when high ISOPOOH sampling periods immediately precede periods of low HCHO.

  18. Rapid protein global fold determination using ultrasparse sampling, high-dynamic range artifact suppression, and time-shared NOESY.

    Science.gov (United States)

    Coggins, Brian E; Werner-Allen, Jonathan W; Yan, Anthony; Zhou, Pei

    2012-11-14

    In structural studies of large proteins by NMR, global fold determination plays an increasingly important role in providing a first look at a target's topology and reducing assignment ambiguity in NOESY spectra of fully protonated samples. In this work, we demonstrate the use of ultrasparse sampling, a new data processing algorithm, and a 4-D time-shared NOESY experiment (1) to collect all NOEs in (2)H/(13)C/(15)N-labeled protein samples with selectively protonated amide and ILV methyl groups at high resolution in only four days, and (2) to calculate global folds from this data using fully automated resonance assignment. The new algorithm, SCRUB, incorporates the CLEAN method for iterative artifact removal but applies an additional level of iteration, permitting real signals to be distinguished from noise and allowing nearly all artifacts generated by real signals to be eliminated. In simulations with 1.2% of the data required by Nyquist sampling, SCRUB achieves a dynamic range over 10000:1 (250× better artifact suppression than CLEAN) and completely quantitative reproduction of signal intensities, volumes, and line shapes. Applied to 4-D time-shared NOESY data, SCRUB processing dramatically reduces aliasing noise from strong diagonal signals, enabling the identification of weak NOE crosspeaks with intensities 100× less than those of diagonal signals. Nearly all of the expected peaks for interproton distances under 5 Å were observed. The practical benefit of this method is demonstrated with structure calculations for 23 kDa and 29 kDa test proteins using the automated assignment protocol of CYANA, in which unassigned 4-D time-shared NOESY peak lists produce accurate and well-converged global fold ensembles, whereas 3-D peak lists either fail to converge or produce significantly less accurate folds. The approach presented here succeeds with an order of magnitude less sampling than required by alternative methods for processing sparse 4-D data.

  19. Reduction hybrid artifacts of EMG-EOG in electroencephalography evoked by prefrontal transcranial magnetic stimulation

    Science.gov (United States)

    Bai, Yang; Wan, Xiaohong; Zeng, Ke; Ni, Yinmei; Qiu, Lirong; Li, Xiaoli

    2016-12-01

    Objective. When prefrontal-transcranial magnetic stimulation (p-TMS) performed, it may evoke hybrid artifact mixed with muscle activity and blink activity in EEG recordings. Reducing this kind of hybrid artifact challenges the traditional preprocessing methods. We aim to explore method for the p-TMS evoked hybrid artifact removal. Approach. We propose a novel method used as independent component analysis (ICA) post processing to reduce the p-TMS evoked hybrid artifact. Ensemble empirical mode decomposition (EEMD) was used to decompose signal into multi-components, then the components were separated with artifact reduced by blind source separation (BSS) method. Three standard BSS methods, ICA, independent vector analysis, and canonical correlation analysis (CCA) were tested. Main results. Synthetic results showed that EEMD-CCA outperformed others as ICA post processing step in hybrid artifacts reduction. Its superiority was clearer when signal to noise ratio (SNR) was lower. In application to real experiment, SNR can be significantly increased and the p-TMS evoked potential could be recovered from hybrid artifact contaminated signal. Our proposed method can effectively reduce the p-TMS evoked hybrid artifacts. Significance. Our proposed method may facilitate future prefrontal TMS-EEG researches.

  20. The Importance of Preserving Paper-Based Artifacts in a Digital Age

    Science.gov (United States)

    Bee, Robert

    2008-01-01

    The preservation of paper-based artifacts is an essential issue for collection management in academic libraries. In recent years, the library science profession has often favored reformatting through microfilm or digitization, assuming too quickly that information matters, whereas an artifact's medium does not. However, much recent humanities…

  1. Online Help-Seeking in Communities of Practice: Modeling the Acceptance of Conceptual Artifacts

    Science.gov (United States)

    Nistor, Nicolae; Schworm, Silke; Werner, Matthias

    2012-01-01

    Interactive online help systems are considered to be a fruitful supplement to traditional IT helpdesks, which are often overloaded. They often comprise user-generated FAQ collections playing the role of technology-based conceptual artifacts. Two main questions arise: how the conceptual artifacts should be used, and which factors influence their…

  2. Examining Student Digital Artifacts during a Year-Long Technology Integration Initiative

    Science.gov (United States)

    Rodriguez, Prisca M.; Frey, Chris; Dawson, Kara; Liu, Feng; Ritzhaupt, Albert D.

    2012-01-01

    This study was situated within a year-long, statewide technology integration initiative designed to support technology integration within science, technology, engineering, and math classrooms. It examined the elements used in student artifacts in an attempt to investigate trends in digital artifact creation. Among several conclusions, this…

  3. Presenting Cultural Artifacts in the Art Museum: A University-Museum Collaboration

    Science.gov (United States)

    Chung, Sheng Kuan

    2009-01-01

    With increasing emphasis on multicultural art education and integrative pedagogy, educators have incorporated community resources, such as cultural artifacts exhibited in art museums, to enrich their programs. Cultural artifacts are human-made objects which generally reveal historic information about cultural values, beliefs, and traditions.…

  4. 3D Prior Image Constrained Projection Completion for X-ray CT Metal Artifact Reduction

    NARCIS (Netherlands)

    Mehranian, Abolfazl; Ay, Mohammad Reza; Rahmim, Arman; Zaidi, Habib

    2013-01-01

    The presence of metallic implants in the body of patients undergoing X-ray computed tomography (CT) examinations often results insevere streaking artifacts that degrade image quality. In this work, we propose a new metal artifact reduction (MAR) algorithm for 2D fan-beam and 3D cone-beam CT based on

  5. The Designing Mind: Children's Reasoning about Intended Function and Artifact Structure

    Science.gov (United States)

    Kelemen, Deborah; Seston, Rebecca; Saint Georges, Laure

    2012-01-01

    There is currently debate about the emergence of children's ability to reason about artifacts by reference to their intended design. We present two studies demonstrating that, while 3-year-olds have emerging insights, 4-year-old children display an explicit, well-rounded, adult-like understanding of the way design constrains an artifact's physical…

  6. A standardized evaluation of artifacts from metallic compounds during fast MR imaging

    DEFF Research Database (Denmark)

    Murakami, Shumei; Verdonschot, Rinus G; Kataoka, Miyoshi

    2016-01-01

    OBJECTIVE: Metallic compounds present in the oral and maxillofacial regions (OMR) cause large artifacts during MR scanning. We quantitatively assessed these artifacts embedded within a phantom according to standards set by the American Society for Testing and Materials (ASTM). MATERIALS AND METHO...

  7. The Role of Classroom Artifacts in the Clinical Supervision of Science.

    Science.gov (United States)

    Pyle, Eric J.

    1998-01-01

    Classroom artifacts, physical objects produced by teachers or students for specific instructional purposes, have a special importance in science instruction. Article uses three examples of supervisory styles (directive, collaborative, and nondirective) to illustrate how a supervisor might approach the use of artifacts while assisting a science…

  8. Artifacts in research data obtained from an anesthesia information and management system

    NARCIS (Netherlands)

    Kool, Nathalie P.; van Waes, Judith A. R.; Bijker, Jilles B.; Peelen, Linda M.; van Wolfswinkel, Leo; de Graaff, Jurgen C.; van Klei, Wilton A.

    2012-01-01

    Artifacts in anesthesia information management system (AIMS) databases may influence research results. Filtering during data capturing can prevent artifacts from being stored. In this prospective study, we assessed the reliability of AIMS data by determining the incidence of artifactual values store

  9. Was It Designed to Do That? Children's Focus on Intended Function in Their Conceptualization of Artifacts

    Science.gov (United States)

    Asher, Yvonne M.; Kemler Nelson, Deborah G.

    2008-01-01

    Do young children who seek the conceptual kind of an artifact weigh the plausibility that a current function constitutes the function intended by the object designer? Three- and four-year-olds were encouraged to question adults about novel artifacts. After inquiring about what an object was, some children were shown a function that plausibly…

  10. Communicative Function Demonstration Induces Kind-Based Artifact Representation in Preverbal Infants

    Science.gov (United States)

    Futo, Judit; Teglas, Erno; Csibra, Gergely; Gergely, Gyorgy

    2010-01-01

    Human infants grow up in environments populated by artifacts. In order to acquire knowledge about different kinds of human-made objects, children have to be able to focus on the information that is most relevant for sorting artifacts into categories. Traditional theories emphasize the role of superficial, perceptual features in object…

  11. Reasoning about Artifacts at 24 Months: The Developing Teleo-Functional Stance

    Science.gov (United States)

    Casler, Krista; Kelemen, Deborah

    2007-01-01

    From the age of 2.5, children use social information to rapidly form enduring function-based artifact categories. The present study asked whether even younger children likewise constrain their use of objects according to teleo-functional beliefs that artifacts are "for" particular purposes, or whether they use objects as means to any desired end.…

  12. Evaluation of MRI artifacts at 3 Tesla for 38 commonly used cosmetics.

    Science.gov (United States)

    Escher, Kirin; Shellock, Frank G

    2013-06-01

    To evaluate MRI artifacts at 3-Tesla for 38 commonly used cosmetics. Thirty-eight cosmetics (16, nail polishes; 5, eyeliners; 3, mascaras; 10, eye shadows; 1, lip gloss; 1, body lotion; 1, body glitter, and 1, hair loss concealer) underwent evaluation for MRI artifacts at 3-Tesla. The cosmetics were applied a copper-sulfate-filled, phantom and initially assessed using a "screening" gradient echo (GRE) pulse sequence. Of the 38 different cosmetics, 14 (37%) exhibited artifacts. For these 14 cosmetics, additional characterization of artifacts was performed using a GRE pulse sequence. A qualitative scale was applied to characterize the artifact size. Artifacts were observed, as follows: 2, nail polishes; 5, eyeliners; 3, mascaras; 3, eye shadows; 1, hair loss concealer. Artifact size ranged from small (eye shadow) to very large (hair loss concealer) and tended to be associated with the presence of iron oxide or other metal-based ingredient. Commonly used cosmetics caused artifacts that may create issues if the area of interest is the same as where the cosmetic was applied or if its presence was unknown, thus, potentially causing it to be construed as pathology. Therefore, these findings have important implications for patients referred for MRI examinations. Copyright © 2013 Elsevier Inc. All rights reserved.

  13. Automated Classification and Removal of EEG Artifacts with SVM and Wavelet-ICA.

    Science.gov (United States)

    Sai, Chong Yeh; Mokhtar, Norrima; Arof, Hamzah; Cumming, Paul; Iwahashi, Masahiro

    2017-07-04

    Brain electrical activity recordings by electroencephalography (EEG) are often contaminated with signal artifacts. Procedures for automated removal of EEG artifacts are frequently sought for clinical diagnostics and brain computer interface (BCI) applications. In recent years, a combination of independent component analysis (ICA) and discrete wavelet transform (DWT) has been introduced as standard technique for EEG artifact removal. However, in performing the wavelet-ICA procedure, visual inspection or arbitrary thresholding may be required for identifying artifactual components in the EEG signal. We now propose a novel approach for identifying artifactual components separated by wavelet-ICA using a pre-trained support vector machine (SVM). Our method presents a robust and extendable system that enables fully automated identification and removal of artifacts from EEG signals, without applying any arbitrary thresholding. Using test data contaminated by eye blink artifacts, we show that our method performed better in identifying artifactual components than did existing thresholding methods. Furthermore, wavelet-ICA in conjunction with SVM successfully removed target artifacts, while largely retaining the EEG source signals of interest. We propose a set of features including kurtosis, variance, Shannon's entropy and range of amplitude as training and test data of SVM to identify eye blink artifacts in EEG signals. This combinatorial method is also extendable to accommodate multiple types of artifacts present in multi-channel EEG. We envision future research to explore other descriptive features corresponding to other types of artifactual components.

  14. An evaluation of three commercially available metal artifact reduction methods for CT imaging

    Science.gov (United States)

    Huang, Jessie Y.; Kerns, James R.; Nute, Jessica L.; Liu, Xinming; Balter, Peter A.; Stingo, Francesco C.; Followill, David S.; Mirkovic, Dragan; Howell, Rebecca M.; Kry, Stephen F.

    2015-02-01

    Three commercial metal artifact reduction methods were evaluated for use in computed tomography (CT) imaging in the presence of clinically realistic metal implants: Philips O-MAR, GE’s monochromatic gemstone spectral imaging (GSI) using dual-energy CT, and GSI monochromatic imaging with metal artifact reduction software applied (MARs). Each method was evaluated according to CT number accuracy, metal size accuracy, and streak artifact severity reduction by using several phantoms, including three anthropomorphic phantoms containing metal implants (hip prosthesis, dental fillings and spinal fixation rods). All three methods showed varying degrees of success for the hip prosthesis and spinal fixation rod cases, while none were particularly beneficial for dental artifacts. Limitations of the methods were also observed. MARs underestimated the size of metal implants and introduced new artifacts in imaging planes beyond the metal implant when applied to dental artifacts, and both the O-MAR and MARs algorithms induced artifacts for spinal fixation rods in a thoracic phantom. Our findings suggest that all three artifact mitigation methods may benefit patients with metal implants, though they should be used with caution in certain scenarios.

  15. A Review of the Performance of Artifact Filtering Algorithms for Cardiopulmonary Resuscitation

    Directory of Open Access Journals (Sweden)

    Yushun Gong

    2013-01-01

    Full Text Available Various filtering strategies have been adopted and investigated to suppress the cardiopulmonary resuscitation (CPR artifact. In this article, two types of artifact removal methods are reviewed: one is the method that removes CPR artifact using only ECG signals, and the other is the method with additional reference signals, such as acceleration, compression depth and transthoracic impedance. After filtering, the signal-to-noise ratio is improved from 0 dB to greater than 2.8 dB, the sensitivity is increased to > 90% as recommended by the American Heart Association, whereas the specificity was far from the recommended 95%, which is considered to be the major drawback of the available artifact removal methods. The overall performance of the adaptive filtering methods with additional reference signal outperforms the methods using only ECG signals. Further research should focus on the refinement of artifact filtering methods and the improvement of shock advice algorithms with the presence of CPR.

  16. Artifacts, intentions, and contraceptives: the problem with having a plan B for plan B.

    Science.gov (United States)

    Reed, Philip A

    2013-12-01

    It is commonly proposed that artifacts cannot be understood without reference to human intentions. This fact, I contend, has relevance to the use of artifacts in intentional action. I argue that because artifacts have intentions embedded into them antecedently, when we use artifacts we are sometimes compelled to intend descriptions of our actions that we might, for various reasons, be inclined to believe that we do not intend. I focus this argument to a specific set of artifacts, namely, medical devices, before considering an extended application to emergency contraceptive devices. Although there is some debate about whether emergency contraception has an abortifacient effect, I argue that if there is an abortifacient effect, then the effect cannot normally be a side effect of one's action.

  17. Using an injection signal to reduce motion artifacts in capacitive ECG measurements.

    Science.gov (United States)

    Serteyn, Aline; Vullings, Rik; Meftah, Mohammed; Bergmans, Jan

    2013-01-01

    Capacitive electrodes are a promising alternative to the conventional adhesive ECG electrodes. They provide more comfort to the patient when integrated in everyday objects (e.g. beds or seats) for long-term monitoring. However, the application of such electrodes is limited by their high sensitivity to motion artifacts. Artifacts caused by variation of the coupling capacitance are studied here. An injection signal is proposed to track these variations in real-time. An adaptive filter then estimates the motion artifact and cancels it from the recorded ECG. The amplitude of the motion artifact is reduced in average by 29 dB in simulation and by 20 dB in a lab environment. Our method has the advantages that it is able to reduce motion artifacts occurring in the frequency band of the ECG and that it does not require knowledge about the measurement system.

  18. Are Movement Artifacts in Magnetic Resonance Imaging a Real Problem?-A Narrative Review

    DEFF Research Database (Denmark)

    Havsteen, Inger; Ohlhues, Anders; Madsen, Kristoffer H

    2017-01-01

    Movement artifacts compromise image quality and may interfere with interpretation, especially in magnetic resonance imaging (MRI) applications with low signal-to-noise ratio such as functional MRI or diffusion tensor imaging, and when imaging small lesions. High image resolution has high sensitiv......Movement artifacts compromise image quality and may interfere with interpretation, especially in magnetic resonance imaging (MRI) applications with low signal-to-noise ratio such as functional MRI or diffusion tensor imaging, and when imaging small lesions. High image resolution has high...... sensitivity to motion artifacts and often prolongs scan time that again aggravates movement artifacts. During the scan fast imaging techniques and sequences, optimal receiver coils, careful patient positioning, and instruction may minimize movement artifacts. Physiological noise sources are motion from...

  19. Automatic detection and classification of artifacts in single-channel EEG

    DEFF Research Database (Denmark)

    Olund, Thomas; Duun-Henriksen, Jonas; Kjaer, Troels W.

    2014-01-01

    Ambulatory EEG monitoring can provide medical doctors important diagnostic information, without hospitalizing the patient. These recordings are however more exposed to noise and artifacts compared to clinically recorded EEG. An automatic artifact detection and classification algorithm for single......-channel EEG is proposed to help identifying these artifacts. Features are extracted from the EEG signal and wavelet subbands. Subsequently a selection algorithm is applied in order to identify the best discriminating features. A non-linear support vector machine is used to discriminate among different...... artifact classes using the selected features. Single-channel (Fp1-F7) EEG recordings are obtained from experiments with 12 healthy subjects performing artifact inducing movements. The dataset was used to construct and validate the model. Both subject-specific and generic implementation, are investigated...

  20. What Do Artifacts Do?-An Anthropological Approach to Materiality

    Institute of Scientific and Technical Information of China (English)

    Michael Rowlands; Tang Yun; Zhang Lisheng

    2015-01-01

    I rather deliberately use artifact and object in my title rather than thing and thingness. My aim is to emphasise the ars/artis element of making/fabricating and facts /objects as outcomes/realities. Bruno Latour has made an elegant pas-tiche of the terms fetish and fact to create hybrid factiches - which I am certainly taking advantage of. My focus is also Theodore Adorno’s use of the term object to characterise why it is so often used negatively as the decontextualised object. The quote I want to use is from the beginning of his article Valery Proust Museum in the collection Prisms –“The German word museal ( museum like ) has un-pleasant overtones. It describes objects to which the observer no longer has any vital relationship and which are in the process of dying. They owe their preservation more to historical respect than to the needs of the present.” Thankfully a little later he goes on to say:“One cannot be content,however, with the general recognition of a negative situation. An intellectual dispute like this must be fought out with specific arguments.” So I want to present one to retrieve the value of de-contextualised objects. In the back of my mind is that other dispute on this theme in archaeological dialogues. Tim In-gold takes materials seriously and accuses the ma-terial culture bunch at UCL ( University College London) of reducing materials to social relations or sociality. A seemingly unlikely hero for Tim Ingold is Henry Hodges who wrote a book Artifacts. Ingold advocates the autonomy of the object/ materials separately from peoples’ intentions towards them. In his response to Tim Ingold, Danny Miller accused him of primitivism - a desire to naturalise the world – see us all inhabiting it through natural processes of self-making - making things /doing things for ourselves. Instead of the Stone Age–he says –we live in a Plastic Age - we encounter the material world already made – and we re-sponds as consumers in acts of

  1. Metal artifact reduction in MRI-based cervical cancer intracavitary brachytherapy

    Science.gov (United States)

    Rao, Yuan James; Zoberi, Jacqueline E.; Kadbi, Mo; Grigsby, Perry W.; Cammin, Jochen; Mackey, Stacie L.; Garcia-Ramirez, Jose; Goddu, S. Murty; Schwarz, Julie K.; Gach, H. Michael

    2017-04-01

    Magnetic resonance imaging (MRI) plays an increasingly important role in brachytherapy planning for cervical cancer. Yet, metal tandem, ovoid intracavitary applicators, and fiducial markers used in brachytherapy cause magnetic susceptibility artifacts in standard MRI. These artifacts may impact the accuracy of brachytherapy treatment and the evaluation of tumor response by misrepresenting the size and location of the metal implant, and distorting the surrounding anatomy and tissue. Metal artifact reduction sequences (MARS) with high bandwidth RF selective excitations and turbo spin-echo readouts were developed for MRI of orthopedic implants. In this study, metal artifact reduction was applied to brachytherapy of cervical cancer using the orthopedic metal artifact reduction (O-MAR) sequence. O-MAR combined MARS features with view angle tilting and slice encoding for metal artifact correction (SEMAC) to minimize in-plane and through-plane susceptibility artifacts. O-MAR improved visualization of the tandem tip on T2 and proton density weighted (PDW) imaging in phantoms and accurately represented the diameter of the tandem. In a pilot group of cervical cancer patients (N  =  7), O-MAR significantly minimized the blooming artifact at the tip of the tandem in PDW MRI. There was no significant difference observed in artifact reduction between the weak (5 kHz, 7 z-phase encodes) and medium (10 kHz, 13 z-phase encodes) SEMAC settings. However, the weak setting allowed a significantly shorter acquisition time than the medium setting. O-MAR also reduced susceptibility artifacts associated with metal fiducial markers so that they appeared on MRI at their true dimensions.

  2. Two Methods for Antialiased Wireframe Drawing with Hidden Line Removal

    DEFF Research Database (Denmark)

    Bærentzen, Jakob Andreas; Munk-Lund, Steen; Gjøl, Mikkel

    2008-01-01

    Two novel and robust techniques for wireframe drawing are proposed. Neither suffer from the well-known artifacts associated with the standard two pass, offset based techniques for wireframe drawing. Both methods draw prefiltered lines and produce high-quality antialiased results without super...

  3. A systematic investigation of differential effects of cell culture substrates on the extent of artifacts in single-molecule tracking.

    Directory of Open Access Journals (Sweden)

    Laura C Zanetti-Domingues

    Full Text Available Single-molecule techniques are being increasingly applied to biomedical investigation, notwithstanding the numerous challenges they pose in terms of signal-to-noise ratio issues. Non-specific binding of probes to glass substrates, in particular, can produce experimental artifacts due to spurious molecules on glass, which can be particularly deleterious in live-cell tracking experiments. In order to resolve the issue of non-specific probe binding to substrates, we performed systematic testing of a range of available surface coatings, using three different proteins, and then extended our assessment to the ability of these coatings to foster cell growth and retain non-adhesive properties. Linear PEG, a passivating agent commonly used both in immobilized-molecule single-molecule techniques and in tissue engineering, is able to both successfully repel non-specific adhesion of fluorescent probes and to foster cell growth when functionalized with appropriate adhesive peptides. Linear PEG treatment results in a significant reduction of tracking artifacts in EGFR tracking with Affibody ligands on a cell line expressing EGFR-eGFP. The findings reported herein could be beneficial to a large number of experimental situations where single-molecule or single-particle precision is required.

  4. SAMPLING ARTIFACTS IN MEASUREMENT OF ELEMENTAL AND ORGANIC CARBON: LOW VOLUME SAMPLING IN INDOOR AND OUTDOOR ENVIRONMENTS

    Science.gov (United States)

    Experiments were completed to determine the extent of artifacts from sampling elemental carbon (EC) and organic carbon (OC) under sample conditions consistent with personal sampling. Two different types of experiments were completed; the first examined possible artifacts from oil...

  5. An illustrative review to understand and manage metal-induced artifacts in musculoskeletal MRI: a primer and updates

    Energy Technology Data Exchange (ETDEWEB)

    Dillenseger, J.P.; Choquet, P.; Goetz, C.; Bierry, G. [University Hospital of Strasbourg, Medical Imaging Department, Strasbourg (France); Icube, CNRS, University of Strasbourg, Strasbourg (France); University of Strasbourg, Translational Medicine Research Federation, Strasbourg Medical School, Strasbourg (France); Moliere, S. [University Hospital of Strasbourg, Medical Imaging Department, Strasbourg (France); Ehlinger, M. [Icube, CNRS, University of Strasbourg, Strasbourg (France); University of Strasbourg, Translational Medicine Research Federation, Strasbourg Medical School, Strasbourg (France); University Hospital of Strasbourg, Department of Orthopedic Surgery, Strasbourg (France)

    2016-05-15

    This article reviews and explains the basic physical principles of metal-induced MRI artifacts, describes simple ways to reduce them, and presents specific reduction solutions. Artifacts include signal loss, pile-up artifacts, geometric distortion, and failure of fat suppression. Their nature and origins are reviewed and explained though schematic representations that ease the understanding. Then, optimization of simple acquisition parameters is detailed. Lastly, dedicated sequences and options specifically developed to reduce metal artifacts (VAT, SEMAC, and MAVRIC) are explained. (orig.)

  6. Choice in experiential learning: True preferences or experimental artifacts?

    Science.gov (United States)

    Ashby, Nathaniel J S; Konstantinidis, Emmanouil; Yechiam, Eldad

    2017-02-09

    The rate of selecting different options in the decisions-from-feedback paradigm is commonly used to measure preferences resulting from experiential learning. While convergence to a single option increases with experience, some variance in choice remains even when options are static and offer fixed rewards. Employing a decisions-from-feedback paradigm followed by a policy-setting task, we examined whether the observed variance in choice is driven by factors related to the paradigm itself: Continued exploration (e.g., believing options are non-stationary) or exploitation of perceived outcome patterns (i.e., a belief that sequential choices are not independent). Across two studies, participants showed variance in their choices, which was related (i.e., proportional) to the policies they set. In addition, in Study 2, participants' reported under-confidence was associated with the amount of choice variance in later choices and policies. These results suggest that variance in choice is better explained by participants lacking confidence in knowing which option is better, rather than methodological artifacts (i.e., exploration or failures to recognize outcome independence). As such, the current studies provide evidence for the decisions-from-feedback paradigm's validity as a behavioral research method for assessing learned preferences.

  7. Diagnostic value of chemical shift artifact in distinguishing benign lymphadenopathy

    Energy Technology Data Exchange (ETDEWEB)

    Farshchian, Nazanin, E-mail: farshchian.n@gmail.com [Department of Radiology, Kermanshah University of Medical Sciences, Kermanshah (Iran, Islamic Republic of); Tamari, Saghar; Farshchian, Negin [Department of Radiology, Kermanshah University of Medical Sciences, Kermanshah (Iran, Islamic Republic of); Madani, Hamid [Department of Pathology, Imam-Reza Hospital, Kermanshah University of Medical Sciences, Kermanshah (Iran, Islamic Republic of); Rezaie, Mansour [Department of Biostatistics, Kermanshah University of Medical Sciences, Kermanshah (Iran, Islamic Republic of); Mohammadi-Motlagh, Hamid-Reza, E-mail: mohammadimotlagh@gmail.com [Medical Biology Research Center, Kermanshah University of Medical Sciences, Kermanshah (Iran, Islamic Republic of)

    2011-11-15

    Purpose: Today, distinguishing metastatic lymph nodes from secondary benign inflammatory ones via using non-invasive methods is increasingly favorable. In this study, the diagnostic value of chemical shift artifact (CSA) in magnetic resonance imaging (MRI) was evaluated to distinguish benign lymphadenopathy. Subjects and methods: A prospective intraindividual internal review board-approved study was carried out on 15 men and 15 women having lymphadenopathic lesions in different locations of the body who underwent contrast-enhanced dynamic MR imaging at 1.5 T. Then, the imaging findings were compared with pathology reports, using the statistics analyses. Results: Due to the findings of the CSA existence in MRI, a total of 56.7% of the studied lesions (17 of 30) were identified as benign lesions and the rest were malignant, whereas the pathology reports distinguished twelve malignant and eighteen benign cases. Furthermore, the CSA findings comparing the pathology reports indicated that CSA, with confidence of 79.5%, has a significant diagnostic value to differentiate benign lesions from malignant ones. Conclusion: Our study demonstrated that CSA in MR imaging has a suitable diagnostic potential nearing readiness for clinical trials. Furthermore, CSA seems to be a feasible tool to differentiate benign lymph nodes from malignant ones; however, further studies including larger numbers of patients are required to confirm our results.

  8. Accuracy and artifact: reexamining the intensity bias in affective forecasting.

    Science.gov (United States)

    Levine, Linda J; Lench, Heather C; Kaplan, Robin L; Safer, Martin A

    2012-10-01

    Research on affective forecasting shows that people have a robust tendency to overestimate the intensity of future emotion. We hypothesized that (a) people can accurately predict the intensity of their feelings about events and (b) a procedural artifact contributes to people's tendency to overestimate the intensity of their feelings in general. People may misinterpret the forecasting question as asking how they will feel about a focal event, but they are later asked to report their feelings in general without reference to that event. In the current investigation, participants predicted and reported both their feelings in general and their feelings about an election outcome (Study 1) and an exam grade (Study 3). We also assessed how participants interpreted forecasting questions (Studies 2 and 4) and conducted a meta-analysis of affective forecasting research (Study 5). The results showed that participants accurately predicted the intensity of their feelings about events. They overestimated only when asked to predict how they would feel in general and later report their feelings without reference to the focal event. Most participants, however, misinterpreted requests to predict their feelings in general as asking how they would feel when they were thinking about the focal event. Clarifying the meaning of the forecasting question significantly reduced overestimation. These findings reveal that people have more sophisticated self-knowledge than is commonly portrayed in the affective forecasting literature. Overestimation of future emotion is partly due to a procedure in which people predict one thing but are later asked to report another.

  9. Anticoagulant Effect of Sugammadex: Just an In Vitro Artifact.

    Science.gov (United States)

    Dirkmann, Daniel; Britten, Martin W; Pauling, Henning; Weidle, Juliane; Volbracht, Lothar; Görlinger, Klaus; Peters, Jürgen

    2016-06-01

    Sugammadex prolongs activated partial thromboplastin time (aPTT) and prothrombin time (PT) suggestive of anticoagulant effects. To pinpoint its presumed anticoagulant site of action, the authors assessed Sugammadex's impact on a panel of coagulation assays. Sugammadex, Rocuronium, Sugammadex and Rocuronium combined, or saline were added to blood samples from healthy volunteers and analyzed using plasmatic (i.e., aPTT, thrombin time, and fibrinogen concentration) (n = 8 each), PT (quick), activities of plasmatic coagulation factors, and whole blood (extrinsically and intrinsically activated thromboelastometry) assays (n = 18 each). Furthermore, dose-dependent effects of Sugammadex were also assessed (n = 18 each) in diluted Russel viper venom time (DRVVT) assays with low (DRVVT1) and high (DRVVT2) phospholipid concentrations and in a highly phospholipid-sensitive aPTT assay. Sugammadex increased PT (+9.1%; P Sugammadex dose-dependently prolonged both DRVVT1 and the highly phospholipid-sensitive aPTT assays, but additional phospholipids in the DRVVT2 assay almost abolished these prolongations. Thrombin time, a thromboelastometric thrombin generation assay, clot firmness, clot lysis, fibrinogen concentration, and activities of other coagulation factors were unaltered. Rocuronium, Sugammadex and Rocuronium combined, and saline exerted no effects. Sugammadex significantly affects various coagulation assays, but this is explainable by an apparent phospholipid-binding effect, suggesting that Sugammadex`s anticoagulant effects are likely an in vitro artifact.

  10. Protein purification and crystallization artifacts: The tale usually not told.

    Science.gov (United States)

    Niedzialkowska, Ewa; Gasiorowska, Olga; Handing, Katarzyna B; Majorek, Karolina A; Porebski, Przemyslaw J; Shabalin, Ivan G; Zasadzinska, Ewelina; Cymborowski, Marcin; Minor, Wladek

    2016-03-01

    The misidentification of a protein sample, or contamination of a sample with the wrong protein, may be a potential reason for the non-reproducibility of experiments. This problem may occur in the process of heterologous overexpression and purification of recombinant proteins, as well as purification of proteins from natural sources. If the contaminated or misidentified sample is used for crystallization, in many cases the problem may not be detected until structures are determined. In the case of functional studies, the problem may not be detected for years. Here several procedures that can be successfully used for the identification of crystallized protein contaminants, including: (i) a lattice parameter search against known structures, (ii) sequence or fold identification from partially built models, and (iii) molecular replacement with common contaminants as search templates have been presented. A list of common contaminant structures to be used as alternative search models was provided. These methods were used to identify four cases of purification and crystallization artifacts. This report provides troubleshooting pointers for researchers facing difficulties in phasing or model building.

  11. Buildings as Artifacts: Heritage, Patriotism, and the Constructed Landscape

    Directory of Open Access Journals (Sweden)

    Kristin Marie Barry

    2017-01-01

    Full Text Available Architectural collections or reconstructed villages are popular tourist attractions in Europe and the United States, often promoting architecture as a demonstration of national and regional heritages. At times, these sites betray the biases of their creators, perpetuated through methods of display and their public interpretation. The architecture can be used as artifact or backdrop to promote ethics, history, or industry at the hand of curators, particularly when removed from its original context and constructed in a new one. When viewed through the lens of tourism, the collections become a constructed landscape of architectural heritage, experienced by visitors through a narrow understanding of time and place, propagated by fabricated historical connections or purposeful nationalist arrangements. Often accessorizing ‘authentic’ architectural heritage with reconstructions and reproductions, these collections suggest a skewed heritage landscape to the non-specialized visitor, emphasizing tourism over truth and entertainment over education. Following 19th century examples in Scandinavia and the broader introduction of international architecture through the 1893 World’s Columbian Exposition, early 20th century American collections at Greenfield Village and the Manitou Cliff Dwellings underscore the intent to capitalize on architectural heritage tourism, and how a diluted history is interpreted through the eyes of the modern tourist.

  12. Are GRB Blackbodies an Artifact of Spectral Evolution?

    CERN Document Server

    Burgess, J Michael

    2014-01-01

    The analysis of gamma-ray burst (GRB) spectra with multi-component emission models has become an important part of the field. In particular, multi-component analysis where one component is a blackbody representing emission from a photosphere has enabled both a more detailed understanding of the energy content of the jet as well as the ability to examine the dynamic structure of the outflow. While the existence of a blackbody-like component has been shown to be significant and not a byproduct of background fluctuations, it is very possible that it can be an artifact of spectral evolution of a single component that is being poorly resolved in time. Herein, this possibility is tested by simulating a single component evolving in time and then folding the spectra through the $Fermi$ detector response to generate time-tagged event Gamma-ray Burst Monitor (GBM) data. We then fit both the time integrated and resolved generated spectral data with a multi-component model using standard tools. It is found that in {\\it t...

  13. Automatic detection of artifacts in converted S3D video

    Science.gov (United States)

    Bokov, Alexander; Vatolin, Dmitriy; Zachesov, Anton; Belous, Alexander; Erofeev, Mikhail

    2014-03-01

    In this paper we present algorithms for automatically detecting issues specific to converted S3D content. When a depth-image-based rendering approach produces a stereoscopic image, the quality of the result depends on both the depth maps and the warping algorithms. The most common problem with converted S3D video is edge-sharpness mismatch. This artifact may appear owing to depth-map blurriness at semitransparent edges: after warping, the object boundary becomes sharper in one view and blurrier in the other, yielding binocular rivalry. To detect this problem we estimate the disparity map, extract boundaries with noticeable differences, and analyze edge-sharpness correspondence between views. We pay additional attention to cases involving a complex background and large occlusions. Another problem is detection of scenes that lack depth volume: we present algorithms for detecting at scenes and scenes with at foreground objects. To identify these problems we analyze the features of the RGB image as well as uniform areas in the depth map. Testing of our algorithms involved examining 10 Blu-ray 3D releases with converted S3D content, including Clash of the Titans, The Avengers, and The Chronicles of Narnia: The Voyage of the Dawn Treader. The algorithms we present enable improved automatic quality assessment during the production stage.

  14. Skin artifact removal technique for breast cancer radar detection

    Science.gov (United States)

    Caorsi, S.; Lenzi, C.

    2016-06-01

    In this paper we propose a new model-based skin artifact cleaning technique with the aim to remove skin reflections with good effectiveness, without introducing significant signal distortions, and without assuming a priori information on the real structure of the breast. The reference cleaning model, constituted by a two-layer geometry skin-adipose tissue, is oriented to all the ultrawideband radar methods able to detect the tumor starting by the knowledge of each trace recorded around the breast. All the radar signal measurements were simulated by using realistic breast models derived from the University of Wisconsin computational electromagnetic laboratory database and the finite difference time domain (FDTD)-based open source software GprMax. First, we have searched for the best configuration for the reference cleaning model with the aim to minimize the distortions introduced on the radar signal. Second, the performance of the proposed cleaning technique has been assessed by using a breast cancer radar detection technique based on the use of artificial neural network (ANN). In order to minimize the signal distortions, we found that it was necessary to use the real skin thickness and the static Debye parameters of both skin and adipose tissue. In such a case the ANN-based radar approach was able to detect the tumor with an accuracy of 87%. By extending the performance assessment also to the case when only average standard values are used to characterize the reference cleaning model, the detection accuracy was of 84%.

  15. Closed-Loop Control of Myoelectric Prostheses With Electrotactile Feedback: Influence of Stimulation Artifact and Blanking.

    Science.gov (United States)

    Hartmann, Cornelia; Dosen, Strahinja; Amsuess, Sebastian; Farina, Dario

    2015-09-01

    Electrocutaneous stimulation is a promising approach to provide sensory feedback to amputees, and thus close the loop in upper limb prosthetic systems. However, the stimulation introduces artifacts in the recorded electromyographic (EMG) signals, which may be detrimental for the control of myoelectric prostheses. In this study, artifact blanking with three data segmentation approaches was investigated as a simple method to restore the performance of pattern recognition in prosthesis control (eight motions) when EMG signals are corrupted by stimulation artifacts. The methods were tested over a range of stimulation conditions and using four feature sets, comprising both time and frequency domain features. The results demonstrated that when stimulation artifacts were present, the classification performance improved with blanking in all tested conditions. In some cases, the classification performance with blanking was at the level of the benchmark (artifact-free data). The greatest pulse duration and frequency that allowed a full performance recovery were 400 μs and 150 Hz, respectively. These results show that artifact blanking can be used as a practical solution to eliminate the negative influence of the stimulation artifact on EMG pattern classification in a broad range of conditions, thus allowing to close the loop in myoelectric prostheses using electrotactile feedback.

  16. High-throughput ocular artifact reduction in multichannel electroencephalography (EEG) using component subspace projection.

    Science.gov (United States)

    Ma, Junshui; Bayram, Sevinç; Tao, Peining; Svetnik, Vladimir

    2011-03-15

    After a review of the ocular artifact reduction literature, a high-throughput method designed to reduce the ocular artifacts in multichannel continuous EEG recordings acquired at clinical EEG laboratories worldwide is proposed. The proposed method belongs to the category of component-based methods, and does not rely on any electrooculography (EOG) signals. Based on a concept that all ocular artifact components exist in a signal component subspace, the method can uniformly handle all types of ocular artifacts, including eye-blinks, saccades, and other eye movements, by automatically identifying ocular components from decomposed signal components. This study also proposes an improved strategy to objectively and quantitatively evaluate artifact reduction methods. The evaluation strategy uses real EEG signals to synthesize realistic simulated datasets with different amounts of ocular artifacts. The simulated datasets enable us to objectively demonstrate that the proposed method outperforms some existing methods when no high-quality EOG signals are available. Moreover, the results of the simulated datasets improve our understanding of the involved signal decomposition algorithms, and provide us with insights into the inconsistency regarding the performance of different methods in the literature. The proposed method was also applied to two independent clinical EEG datasets involving 28 volunteers and over 1000 EEG recordings. This effort further confirms that the proposed method can effectively reduce ocular artifacts in large clinical EEG datasets in a high-throughput fashion.

  17. A novel neural network with Non-Recursive IIR Filters on EEG Artifacts Elimination.

    Science.gov (United States)

    Miyazaki, Ryota; Ohshiro, Masakuni; Nishimura, Toshihiro; Tsubai, Masayoshi

    2005-01-01

    The artifacts caused by various factors, EOG (electrooculogram), blink and EMG (electromyogram), in EEG (Electroencephalogram) signals increase the difficulty in analyzing them. In addition, EEG signals containing artifacts often cannot be used in analyzing them. So, it is useful and indispensable to eliminate the artifacts from EEG signals. In this paper, a neural network with non-recursive IIR (Infinite Impulse Response) filters are used to eliminate the artifacts from EEG signals. The proposed method is a new approach that is respect to slotting a non-recursive IIR filter into individual neurons of a neural network. First of all, in order to investigate the usefulness of the proposed method in eliminating the artifacts from EEG signals, we apply it to the artificial EEG signals that are weakly stationary process. As the result, the artifacts can be eliminated from EEG signals almost exactly using the proposed method, and it is suggested the proposed method should be useful in eliminating the artifacts from EEG signals.

  18. Methods for artifact detection and removal from scalp EEG: A review.

    Science.gov (United States)

    Islam, Md Kafiul; Rastegarnia, Amir; Yang, Zhi

    2016-11-01

    Electroencephalography (EEG) is the most popular brain activity recording technique used in wide range of applications. One of the commonly faced problems in EEG recordings is the presence of artifacts that come from sources other than brain and contaminate the acquired signals significantly. Therefore, much research over the past 15 years has focused on identifying ways for handling such artifacts in the preprocessing stage. However, this is still an active area of research as no single existing artifact detection/removal method is complete or universal. This article presents an extensive review of the existing state-of-the-art artifact detection and removal methods from scalp EEG for all potential EEG-based applications and analyses the pros and cons of each method. First, a general overview of the different artifact types that are found in scalp EEG and their effect on particular applications are presented. In addition, the methods are compared based on their ability to remove certain types of artifacts and their suitability in relevant applications (only functional comparison is provided not performance evaluation of methods). Finally, the future direction and expected challenges of current research is discussed. Therefore, this review is expected to be helpful for interested researchers who will develop and/or apply artifact handling algorithm/technique in future for their applications as well as for those willing to improve the existing algorithms or propose a new solution in this particular area of research.

  19. Monoenergetic computed tomography reconstructions reduce beam hardening artifacts from dental restorations.

    Science.gov (United States)

    Stolzmann, Paul; Winklhofer, Sebastian; Schwendener, Nicole; Alkadhi, Hatem; Thali, Michael J; Ruder, Thomas D

    2013-09-01

    The aim of this study was to assess the potential of monoenergetic computed tomography (CT) images to reduce beam hardening artifacts in comparison to standard CT images of dental restoration on dental post-mortem CT (PMCT). Thirty human decedents (15 male, 58 ± 22 years) with dental restorations were examined using standard single-energy CT (SECT) and dual-energy CT (DECT). DECT data were used to generate monoenergetic CT images, reflecting the X-ray attenuation at energy levels of 64, 69, 88 keV, and at an individually adjusted optimal energy level called OPTkeV. Artifact reduction and image quality of SECT and monoenergetic CT were assessed objectively and subjectively by two blinded readers. Subjectively, beam artifacts decreased visibly in 28/30 cases after monoenergetic CT reconstruction. Inter- and intra-reader agreement was good (k = 0.72, and k = 0.73 respectively). Beam hardening artifacts decreased significantly with increasing monoenergies (repeated-measures ANOVA p < 0.001). Artifact reduction was greatest on monoenergetic CT images at OPTkeV. Mean OPTkeV was 108 ± 17 keV. OPTkeV yielded the lowest difference between CT numbers of streak artifacts and reference tissues (-163 HU). Monoenergetic CT reconstructions significantly reduce beam hardening artifacts from dental restorations and improve image quality of post-mortem dental CT.

  20. Image-based iterative compensation of motion artifacts in computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Schretter, Colas; Rose, Georg; Bertram, Matthias [Philips Research Europe, Weisshausstrasse 2, 52066 Aachen, Germany and Otto-von-Guericke University, Universitaetsplatz 2, 39016 Magdeburg (Germany); Otto-von-Guericke University, Universitaetsplatz 2, 39016 Magdeburg (Germany); Philips Research Europe, Weisshausstrasse 2, 52066 Aachen (Germany)

    2009-11-15

    Purpose: This article presents an iterative method for compensation of motion artifacts for slowly rotating computed tomography (CT) systems. Patient's motion introduces inconsistencies among projections and yields severe reconstruction artifacts for free-breathing acquisitions. Streaks and doubling of structures can appear and the resolution is limited by strong blurring. Methods: The rationale of the proposed motion compensation method is to iteratively correct the reconstructed image by first decomposing the perceived motion in projection space, then reconstructing the motion artifacts in image space, and finally subtracting the artifacts from an initial image. The initial image is reconstructed from the acquired data and might contain motion blur artifacts but, nevertheless, is considered as a reference for estimating the reconstruction artifacts. Results: Qualitative and quantitative figures are shown for experiments based on numerically simulated projections of a sequence of clinical images resulting from a respiratory-gated helical CT acquisition. The border of the diaphragm becomes progressively sharper and the contrast improves for small structures in the lungs. Conclusions: The originality of the technique stems from the fact that the patient motion is not explicitly estimated but the motion artifacts are reconstructed in image space. This approach could provide sharp static anatomical images on interventional C-arm systems or on slowly rotating X-ray equipments in radiotherapy.

  1. Automatic Removal of Artifacts from EEG Signal based on Spatially Constrained ICA using Daubechies Wavelet

    Directory of Open Access Journals (Sweden)

    Vandana Roy

    2014-07-01

    Full Text Available This paper presents a boon and amend technique for eradicating the artifacts from the Electroencephalogram (EEG signals. The abolition of artifacts from scalp EEGs is of considerable implication for both the computerized and visual investigation of fundamental brainwave activities. These noise sources increase the difficulty in analyzing the EEG and procurement clinical information related to pathology. Hence it is critical to design a procedure for diminution of such artifacts in EEG archives. This paper uses a blind extraction algorithm, appropriate for the generality of complex-valued sources and both complex noncircular and circular, is introduced. This is achieved based on higher order statistics of dormant sources, and using the de?ation approach Spatially-Constrained Independent Component Analysis (SCICA to separate the Independent Components (ICs from the initial EEG signal. As the next phase, level-4 daubechies wavelet db-4 is applied to extract the brain activity from purged artifacts, and lastly the artifacts are projected back and detracted from EEG signals to get clean EEG data. Here, thresholding plays an imperative role in delineating the artifacts and hence an improved thresholding technique called Otsu’s thresholding is applied. Experimental consequences show that the proposed technique results in better removal of artifacts.

  2. EEG artifact elimination by extraction of ICA-component features using image processing algorithms.

    Science.gov (United States)

    Radüntz, T; Scouten, J; Hochmuth, O; Meffert, B

    2015-03-30

    Artifact rejection is a central issue when dealing with electroencephalogram recordings. Although independent component analysis (ICA) separates data in linearly independent components (IC), the classification of these components as artifact or EEG signal still requires visual inspection by experts. In this paper, we achieve automated artifact elimination using linear discriminant analysis (LDA) for classification of feature vectors extracted from ICA components via image processing algorithms. We compare the performance of this automated classifier to visual classification by experts and identify range filtering as a feature extraction method with great potential for automated IC artifact recognition (accuracy rate 88%). We obtain almost the same level of recognition performance for geometric features and local binary pattern (LBP) features. Compared to the existing automated solutions the proposed method has two main advantages: First, it does not depend on direct recording of artifact signals, which then, e.g. have to be subtracted from the contaminated EEG. Second, it is not limited to a specific number or type of artifact. In summary, the present method is an automatic, reliable, real-time capable and practical tool that reduces the time intensive manual selection of ICs for artifact removal. The results are very promising despite the relatively small channel resolution of 25 electrodes.

  3. 78 FR 74175 - Federal Council on the Arts and the Humanities; Arts and Artifacts Indemnity Panel Advisory...

    Science.gov (United States)

    2013-12-10

    ... ARTS AND THE HUMANITIES Federal Council on the Arts and the Humanities; Arts and Artifacts Indemnity... for Arts and Artifacts Indemnity Panel Advisory Committee. SUMMARY: Pursuant to section 9(a)(2) of the... and Artifacts Indemnity Panel advisory committee was renewed for an additional two-year period...

  4. 15 CFR 270.321 - Entry and inspection of property where building components, materials, artifacts, and records...

    Science.gov (United States)

    2010-01-01

    ... building components, materials, artifacts, and records with respect to a building failure are located. 270... of property where building components, materials, artifacts, and records with respect to a building... building components, materials, artifacts and records with respect to a building failure are...

  5. 15 CFR 270.325 - Notice of authority to enter and inspect property where building components, materials, artifacts...

    Science.gov (United States)

    2010-01-01

    ... inspect property where building components, materials, artifacts, and records with respect to a building... Notice of authority to enter and inspect property where building components, materials, artifacts, and... investigated has occurred, or where building components, materials, and artifacts with respect to the...

  6. An automated method for comparing motion artifacts in cine four-dimensional computed tomography images.

    Science.gov (United States)

    Cui, Guoqiang; Jew, Brian; Hong, Julian C; Johnston, Eric W; Loo, Billy W; Maxim, Peter G

    2012-11-08

    The aim of this study is to develop an automated method to objectively compare motion artifacts in two four-dimensional computed tomography (4D CT) image sets, and identify the one that would appear to human observers with fewer or smaller artifacts. Our proposed method is based on the difference of the normalized correlation coefficients between edge slices at couch transitions, which we hypothesize may be a suitable metric to identify motion artifacts. We evaluated our method using ten pairs of 4D CT image sets that showed subtle differences in artifacts between images in a pair, which were identifiable by human observers. One set of 4D CT images was sorted using breathing traces in which our clinically implemented 4D CT sorting software miscalculated the respiratory phase, which expectedly led to artifacts in the images. The other set of images consisted of the same images; however, these were sorted using the same breathing traces but with corrected phases. Next we calculated the normalized correlation coefficients between edge slices at all couch transitions for all respiratory phases in both image sets to evaluate for motion artifacts. For nine image set pairs, our method identified the 4D CT sets sorted using the breathing traces with the corrected respiratory phase to result in images with fewer or smaller artifacts, whereas for one image pair, no difference was noted. Two observers independently assessed the accuracy of our method. Both observers identified 9 image sets that were sorted using the breathing traces with corrected respiratory phase as having fewer or smaller artifacts. In summary, using the 4D CT data of ten pairs of 4D CT image sets, we have demonstrated proof of principle that our method is able to replicate the results of two human observers in identifying the image set with fewer or smaller artifacts.

  7. MRI中运动伪影分析%Analysis of Motion Artifacts in MRI

    Institute of Scientific and Technical Information of China (English)

    王昭波; 李文华; 王立忠; 曹庆选

    2013-01-01

    Objective To eliminate the motion artifact in MRI imaging , and improve the image quality.Method Analysis and classification of the motion artifacts in 5986 cases with MRI imaging in the most recent year in our hospital .Results According to the causes and characteristics, the MRI motion artifacts can be divided into random independent motion artifacts, respiratory motion artifacts, heart beat artifacts, large vascular pulsation artifacts and flow effect artifacts .Conclusions To improve the quality of MRI image and the diagnostic accuracy , it is important to understand and eliminate these motion artifacts .%目的:消除MRI中的运动伪影,改善MRI图像质量。方法总结我院最近一年的5986例 MRI检查图像,把其中有运动伪影的病例归纳分类,进行伪影分析。结果按照MRI运动伪影的成因及特点,可分为:随机自主运动伪影、呼吸运动伪影、心脏搏动伪影、大血管搏动伪影及流动效应伪影五大类。结论正确认识各种运动伪影的特点,应用相应的校正方法,对改善MRI质量,提高诊断准确率有重要意义。

  8. Targeted principle component analysis: A new motion artifact correction approach for near-infrared spectroscopy

    Directory of Open Access Journals (Sweden)

    Meryem A. Yücel

    2014-03-01

    Full Text Available As near-infrared spectroscopy (NIRS broadens its application area to different age and disease groups, motion artifacts in the NIRS signal due to subject movement is becoming an important challenge. Motion artifacts generally produce signal fluctuations that are larger than physiological NIRS signals, thus it is crucial to correct for them before obtaining an estimate of stimulus evoked hemodynamic responses. There are various methods for correction such as principle component analysis (PCA, wavelet-based filtering and spline interpolation. Here, we introduce a new approach to motion artifact correction, targeted principle component analysis (tPCA, which incorporates a PCA filter only on the segments of data identified as motion artifacts. It is expected that this will overcome the issues of filtering desired signals that plagues standard PCA filtering of entire data sets. We compared the new approach with the most effective motion artifact correction algorithms on a set of data acquired simultaneously with a collodion-fixed probe (low motion artifact content and a standard Velcro probe (high motion artifact content. Our results show that tPCA gives statistically better results in recovering hemodynamic response function (HRF as compared to wavelet-based filtering and spline interpolation for the Velcro probe. It results in a significant reduction in mean-squared error (MSE and significant enhancement in Pearson's correlation coefficient to the true HRF. The collodion-fixed fiber probe with no motion correction performed better than the Velcro probe corrected for motion artifacts in terms of MSE and Pearson's correlation coefficient. Thus, if the experimental study permits, the use of a collodion-fixed fiber probe may be desirable. If the use of a collodion-fixed probe is not feasible, then we suggest the use of tPCA in the processing of motion artifact contaminated data.

  9. Independent component analysis of gait-related movement artifact recorded using EEG electrodes during treadmill walking.

    Directory of Open Access Journals (Sweden)

    Kristine Lynne Snyder

    2015-12-01

    Full Text Available There has been a recent surge in the use of electroencephalography (EEG as a tool for mobile brain imaging due to its portability and fine time resolution. When EEG is combined with independent component analysis (ICA and source localization techniques, it can model electrocortical activity as arising from temporally independent signals located in spatially distinct cortical areas. However, for mobile tasks, it is not clear how movement artifacts influence ICA and source localization. We devised a novel method to collect pure movement artifact data (devoid of any electrophysiological signals with a 256-channel EEG system. We first blocked true electrocortical activity using a silicone swim cap. Over the silicone layer, we placed a simulated scalp with electrical properties similar to real human scalp. We collected EEG movement artifact signals from ten healthy, young subjects wearing this setup as they walked on a treadmill at speeds from 0.4-1.6 m/s. We performed ICA and dipole fitting on the EEG movement artifact data to quantify how accurately these methods would identify the artifact signals as non-neural. ICA and dipole fitting accurately localized 99% of the independent components in non-neural locations or lacked dipolar characteristics. The remaining 1% of sources had locations within the brain volume and low residual variances, but had topographical maps, power spectra, time courses, and event related spectral perturbations typical of non-neural sources. Caution should be exercised when interpreting ICA for data that includes semi-periodic artifacts including artifact arising from human walking. Alternative methods are needed for the identification and separation of movement artifact in mobile EEG signals, especially methods that can be performed in real time. Separating true brain signals from motion artifact could clear the way for EEG brain computer interfaces for assistance during mobile activities, such as walking.

  10. Artifact associated with the use of strong iodine solution (Lugol's) in cone biopsies.

    Science.gov (United States)

    Benda, J A; Lamoreaux, J; Johnson, S R

    1987-05-01

    The preoperative application of strong iodine solution (USP), commonly referred to as Lugol's solution, induces a histologic artifact in epithelial cells of cone biopsy material, most pronounced in dysplastic cells. Cellular shrinkage, cytoplasmic eosinophilia and vacuolization, development of visible intercellular space, and nuclear pyknosis with loss of chromatin detail are the major findings. Since the use of strong iodine solution (USP) is a common practice for delineating the ectocervical extent of disease prior to cone biopsy, the pathologist should recognize the artifact since its presence can make histologic interpretation difficult. Because the artifact may lead to interpretation error, alternatives to strong iodine solution (USP) should be considered.

  11. Analyzing pictorial artifacts from psychotherapy and art therapy when overcoming stress and trauma

    DEFF Research Database (Denmark)

    Gerge, Anna; Pedersen, Inge Nygaard

    2017-01-01

    to look for in pictorial artifacts related overcome traumatization and dissociation. After an introduction to psychotraumatology and it’s adaptions to creative arts therapy and art therapy, a literature review on assessment tools in art therapy, which can be applicable for measuring overcome...... traumatization, will be addressed. The need of a multi-dimensional tool for analysis of pictorial artifacts done in therapy is asked for and the needed components are briefly sketched. Finally the value of pictorial artifacts, made by clients in psycho-social interventions, as valid “windows” of implicit change...

  12. Detection and Separation of Event-related Potentials from Multi-Artifacts Contaminated EEG by Means of Independent Component Analysis

    Institute of Scientific and Technical Information of China (English)

    WANGRong-chang; DUSi-dan; GAODun-tang

    2004-01-01

    Event-related potentials (ERP) is an important type of brain dynamics in human cognition research. However, ERP is often submerged by the spontaneous brain activity EEG, for its relatively tiny scale. Further more, the brain activities collected from scalp electrodes are often inevitably contaminated by several kinds of artifacts, such as blinks, eye movements, muscle noise and power line interference. A new approach to correct these disturbances is presented using independent component analysis (ICA). This technique can effectively detect and extract ERP components from the measured electrodes recordings even if they are heavily contaminated. The results compare favorably to those obtained by parametric modeling. Besides, auto--adaptive projection of decomposed results to ERP components was also given. Through experiments, ICA proves to be highly capable of ERP extraction and S/N ratio improving.

  13. Odd Harmonics in Exoplanet Photometry: Weather or Artifact?

    Science.gov (United States)

    Cowan, Nicolas B.; Chayes, Victoria; Bouffard, Élie; Meynig, Max; Haggard, Hal M.

    2017-01-01

    In addition to the transits of a planet in front of its star and the eclipses of the planet by its star, researchers have reported flux variations at the orbital frequency and its harmonics: planetary reflection and/or emission and Doppler beaming of starlight produce one peak per orbit, while ellipsoidal variations of a tidally distorted star and/or planet produce two maxima per orbit. Researchers have also reported significant photometric variability at three times the orbital frequency, as yet unexplained. Reflected phase variations of homogeneous planets only contain power at the orbital frequency and its even harmonics. We show that odd harmonics can, however, be produced by an edge-on planet with a time-variable map, or an inclined planet with a North-South (N-S) asymmetric map. For tidally-locked planets with thick atmospheres, either of these scenarios entail weather: planets with zero obliquity experience N-S symmetric stellar forcing. North-South asymmetry would therefore suggest stochastic localized features, i.e., weather. However, we find that previous claims of large-amplitude odd modes in Kepler photometry are artifacts of removing planetary transits rather than modeling them. The only reliable claims of odd harmonics remain HAT-P-7b and Kepler-13Ab, for which the third mode amplitude is 6-8% of the planetary flux. Although time-variable albedo maps could in principle explain these odd harmonics, upper-limits on the infrared variability of other hot Jupiters make this scenario unlikely. We recommend further studying the tidal effects of close-in planets on their host stars, as this remains the only plausible hypothesis.

  14. Reducing motion artifacts in photoplethysmograms by using relative sensor motion: phantom study

    NARCIS (Netherlands)

    Wijshoff, R.W.C.G.R.; Mischi, M.; Veen, J.; Van der Lee, A.M.; Aarts, R.M.

    2012-01-01

    Currently, photoplethysmograms (PPGs) are mostly used to determine apatient's blood oxygenation and pulse rate. However, PPG morphologyconveys more information about the patient's cardiovascular status.Extracting this information requires measuring clean PPG waveformsthat are free of artifacts. PPGs

  15. Clean HMBC: Suppression of strong-coupling induced artifacts in HMBC spectra

    DEFF Research Database (Denmark)

    Würtz, Peter; Permi, Perttu; Nielsen, Niels Chr.;

    2008-01-01

    A new experiment, clean HMBC, is introduced for suppression of strong-coupling induced artifacts in HMBC spectra. The culprits of these artifacts are an inherent shortcoming of low-pass J filters in the presence of strong coupling and the 1H p pulse in the middle of the evolution period aimed...... at suppressing evolution under heteronuclear J couplings and 1H chemical shifts. A p pulse causes coherence transfer in strongly coupled spin systems and, as is well known in e.g., homonuclear J spectra, this leads to peaks that would not be there in the absence of strong coupling. Similar artifacts occur...... protons, such as carbohydrates, and the new technique is demonstrated on D-mannose. Finally, a fundamental difference between HMBC and H2BC explains why strong-coupling artifacts are much less of a problem in the latter type of spectra....

  16. Automatic removal of eye movement artifacts from the EEG using ICA and the dipole model

    Institute of Scientific and Technical Information of China (English)

    Weidong Zhou; Jean Gotman

    2009-01-01

    12 patients were analyzed.The experimental results indicate that ICA with the dipole model is very efficient at automatically subtracting the eye movement artifacts,while retaining the EEG slow waves and making their interpretation easier.

  17. Archaeology Through Computational Linguistics: Inscription Statistics Predict Excavation Sites of Indus Valley Artifacts.

    Science.gov (United States)

    Recchia, Gabriel L; Louwerse, Max M

    2016-11-01

    Computational techniques comparing co-occurrences of city names in texts allow the relative longitudes and latitudes of cities to be estimated algorithmically. However, these techniques have not been applied to estimate the provenance of artifacts with unknown origins. Here, we estimate the geographic origin of artifacts from the Indus Valley Civilization, applying methods commonly used in cognitive science to the Indus script. We show that these methods can accurately predict the relative locations of archeological sites on the basis of artifacts of known provenance, and we further apply these techniques to determine the most probable excavation sites of four sealings of unknown provenance. These findings suggest that inscription statistics reflect historical interactions among locations in the Indus Valley region, and they illustrate how computational methods can help localize inscribed archeological artifacts of unknown origin. The success of this method offers opportunities for the cognitive sciences in general and for computational anthropology specifically.

  18. Using artifact methodology to compare learning assistants' and colleagues' classroom practices

    Science.gov (United States)

    Barr, Stephanie A.; Ross, Mike J.; Otero, Valerie

    2012-02-01

    The University of Colorado's LA-Test K-12 research team investigated the classroom practices of former Learning Assistants' who went on to become K-12 teachers. One of the tools used for this analysis of classroom practice was the Scoop Notebook, an instructional artifact package developed to assess teachers' use of reform-oriented practices. In this paper, the authors characterize differences in classroom practices between former Learning Assistants teaching at the secondary level and their colleagues through the collection and analysis of teaching artifacts. Analyses of these artifacts indicate significant differences between LA and non-LA groups. A description of the methodology and implications of using artifact packages to study classroom practice will be discussed, detailing the role of the LA experience in teacher preparation.

  19. An exploratory study on the user experience of foot reflexology therapy using reflexology artifacts

    Science.gov (United States)

    Okere, Hector Chimeremeze; Sulaiman, Suziah; Rambli, Dayang Rohaya Awang; Foong, Oi-Mean

    2015-07-01

    The reputation and significance of foot reflexology therapy has continuously been on the rise. It is currently widely used as a complementary therapy, for stress relief and a potential diagnostic tool. In the society nowadays, there exist a lot of reflexology artifacts that claim to be an alternative substitutes to the traditional foot reflexology practice since the practices promote relaxation and stress relief. However, there has been very little or no attention given towards the verification of such anecdote and the identification of the similarities, differences and opportunities these reflexology artifacts offer. This paper hence aims to address this issue through the exploration of the practices. The study examined the interactive nature of four different sets of common reflexology artifacts from both the patients' and the experts' perspective. Data were collected through audio recorded semi-structured interview. The study findings revealed answers to those anecdotes, highlighting the similarities, difference and opportunities these reflexology artifacts offer. Implications for future research were also discussed.

  20. Stripe and ring artifact removal with combined wavelet--Fourier filtering.

    Science.gov (United States)

    Münch, Beat; Trtik, Pavel; Marone, Federica; Stampanoni, Marco

    2009-05-11

    A fast, powerful and stable filter based on combined wavelet and Fourier analysis for the elimination of horizontal or vertical stripes in images is presented and compared with other types of destriping filters. Strict separation between artifacts and original features allowing both, suppression of the unwanted structures and high degree of preservation of the original image information is endeavoured. The results are validated by visual assessments, as well as by quantitative estimation of the image energy loss. The capabilities and the performance of the filter are tested on a number of case studies related to applications in tomographic imaging. The case studies include (i) suppression of waterfall artifacts in electron microscopy images based on focussed ion beam nanotomography, (ii) removal of different types of ring artifacts in synchrotron based X-ray microtomography and (iii) suppression of horizontal stripe artifacts from phase projections in grating interferometry.

  1. Modeling common dynamics in multichannel signals with applications to artifact and background removal in EEG recordings.

    Science.gov (United States)

    De Clercq, Wim; Vanrumste, Bart; Papy, Jean-Michel; Van Paesschen, Wim; Van Huffel, Sabine

    2005-12-01

    Removing artifacts and background electroencephaloraphy (EEG) from multichannel interictal and ictal EEG has become a major research topic in EEG signal processing in recent years. We applied for this purpose a recently developed subspace-based method for modeling the common dynamics in multichannel signals. When the epileptiform activity is common in the majority of channels and the artifacts appear only in a few channels the proposed method can be used to remove the latter. The performance of the method was tested on simulated data for different noise levels. For high noise levels the method was still able to identify the common dynamics. In addition, the method was applied to real life EEG recordings containing interictal and ictal activity contaminated with muscle artifact. The muscle artifacts were removed successfully. For both the synthetic data and the analyzed real life data the results were compared with the results obtained with principal component analysis (PCA). In both cases, the proposed method performed better than PCA.

  2. Noise-assisted correlation algorithm for suppressing noise-induced artifacts in ultrasonic Nakagami images.

    Science.gov (United States)

    Tsui, Po-Hsiang; Yeh, Chih-Kuang; Huang, Chih-Chung

    2012-05-01

    Ultrasonic Nakagami images can complement conventional B-mode images for scatterer characterization. White noise in anechoic areas leads to artifacts that affect the Nakagami image to characterize tissues. Artifact removal requires rejection of the white noise without deforming the backscattered waveform. This study proposes a noise-assisted correlation algorithm (NCA) and carries out simulations, phantom experiments, and clinical measurements to validate its feasibility and practicality. The simulation results show that the NCA can reject white noise in an anechoic area without any deformation of the backscattered waveforms. The results obtained from phantoms and tissues further demonstrate that the proposed NCA can suppress a Nakagami image artifact without changing the texture of the Nakagami image of the scattering background. The NCA is an essential algorithm to construct artifact-free Nakagami image for correctly reflecting scatterer properties of biological tissues.

  3. Robust Filtering of Artifacts in Difference Imaging for Rapid Transients Detection

    CERN Document Server

    Klencki, Jakub; Kostrzewa-Rutkowska, Zuzanna; Udalski, Andrzej

    2016-01-01

    Real-time analysis and classification of observational data collected within synoptic sky surveys is a huge challenge due to constant growth of data volumes. Machine learning techniques are often applied in order to perform this task automatically. The current bottleneck of transients detection in most surveys is the process of filtering numerous artifacts from candidate detection. We present a new method for automated artifact filtering based on hierarchical unsupervised classifier employing Self-Organizing Maps (SOMs). The system accepts 97 % of real transients and removes 97.5 % of artifacts when tested on the OGLE-IV Transient Detection System. The improvement of the artifacts filtering allowed for single-frame based rapid detections of transients within OGLE-IV, which now alerts on transient discoveries in less than 15 minutes from the image acquisition.

  4. Mitigation of Selected Hanford Site Manhattan Project and Cold War Era Artifacts

    Energy Technology Data Exchange (ETDEWEB)

    Kennedy, Ellen P.; Harvey, David W.

    2006-09-08

    This document is the first time that Manhattan Project and Cold War era artifacts from the Hanford Site have been assembled within a publication. The publication presents photographic and written documentation of a number of Manhattan Project and Cold War era artifacts that were identified and tagged during assessment walk throughs of historic buildings on the Hanford Site but which could not be curated within the Hanford collection because they were too large for long-term storage and/or exhibit purposes or were radiologically contaminated. The significance of the artifacts in this publication and a proposed future appendix is based not on the individual significance of any single artifact but on their collective contribution to the science and engineering of creating plutonium and advancing nuclear technology in nuclear fuel and power.

  5. Reasoning about artifacts at 24 months: the developing teleo-functional stance.

    Science.gov (United States)

    Casler, Krista; Kelemen, Deborah

    2007-04-01

    From the age of 2.5, children use social information to rapidly form enduring function-based artifact categories. The present study asked whether even younger children likewise constrain their use of objects according to teleo-functional beliefs that artifacts are "for" particular purposes, or whether they use objects as means to any desired end. Twenty-four-month-old toddlers learned about two novel tools that were physically equivalent but perceptually distinct; one tool was assigned implicit function information through a short demonstration. At test, toddlers returned to the demonstrated tool when asked to repeat the task, but, unlike older children, also used it for another task. Results imply that at 24 months, toddlers expect artifacts to have functions and proficiently use a model's intentional use to inform tool choices, suggesting cognition that differs from that of tool-using monkeys. However, their artifact representations are not yet specified enough to support exclusive patterns of tool use.

  6. Quantifying the vestibulo-ocular reflex with video-oculography: nature and frequency of artifacts.

    Science.gov (United States)

    Mantokoudis, Georgios; Saber Tehrani, Ali S; Kattah, Jorge C; Eibenberger, Karin; Guede, Cynthia I; Zee, David S; Newman-Toker, David E

    2015-01-01

    Video-oculography devices are now used to quantify the vestibulo-ocular reflex (VOR) at the bedside using the head impulse test (HIT). Little is known about the impact of disruptive phenomena (e.g. corrective saccades, nystagmus, fixation losses, eye-blink artifacts) on quantitative VOR assessment in acute vertigo. This study systematically characterized the frequency, nature, and impact of artifacts on HIT VOR measures. From a prospective study of 26 patients with acute vestibular syndrome (16 vestibular neuritis, 10 stroke), we classified findings using a structured coding manual. Of 1,358 individual HIT traces, 72% had abnormal disruptive saccades, 44% had at least one artifact, and 42% were uninterpretable. Physicians using quantitative recording devices to measure head impulse VOR responses for clinical diagnosis should be aware of the potential impact of disruptive eye movements and measurement artifacts.

  7. A Socio-Cultural Interpretation of Bahamian Urban Architecture and Artifact

    OpenAIRE

    2016-01-01

    This is the author accepted manuscript. The final version is available in ARC Magazine (30 September 2016) via http://arcthemagazine.com/arc/2016/09/a-socio-cultural-interpretation-of-bahamian-urban-architecture-and-artifact/

  8. Measure Lines

    Science.gov (United States)

    Crissman, Sally

    2011-01-01

    One tool for enhancing students' work with data in the science classroom is the measure line. As a coteacher and curriculum developer for The Inquiry Project, the author has seen how measure lines--a number line in which the numbers refer to units of measure--help students not only represent data but also analyze it in ways that generate…

  9. TU-F-CAMPUS-J-04: Evaluation of Metal Artifact Reduction Technique for the Radiation Therapy Planning

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, K; Kuo, H; Ritter, J; Shen, J; Basavatia, A; Yaparpalvi, R; Kalnicki, S [Montefiore Medical Center, Bronx, NY (United States); Tome, W [Montefiore Medical Center, ALBERT EINSTEIN COLLEGE OF MEDICINE, Bronx, NY (United States)

    2015-06-15

    Purpose: To evaluate the feasibility of using a metal artifact reduction technique in depleting metal artifact and its application in improving dose calculation in External Radiation Therapy Planning. Methods: CIRS electron density phantom was scanned with and without steel drill bits placed in some plug holes. Meta artifact reduction software with Metal Deletion Technique (MDT) was used to remove metal artifacts for scanned image with metal. Hounsfield units of electron density plugs from artifact free reference image and MDT processed images were compared. To test the dose calculation improvement after the MDT processed images, clinically approved head and neck plan with manual dental artifact correction was tested. Patient images were exported and processed with MDT and plan was recalculated with new MDT image without manual correction. Dose profiles near the metal artifacts were compared. Results: The MDT used in this study effectively reduced the metal artifact caused by beam hardening and scatter. The windmill around the metal drill was greatly improved with smooth rounded view. Difference of the mean HU in each density plug between reference and MDT images were less than 10 HU in most of the plugs. Dose difference between original plan and MDT images were minimal. Conclusion: Most metal artifact reduction methods were developed for diagnostic improvement purpose. Hence Hounsfield unit accuracy was not rigorously tested before. In our test, MDT effectively eliminated metal artifacts with good HU reproduciblity. However, it can introduce new mild artifacts so the MDT images should be checked with original images.

  10. A robust adaptive denoising framework for real-time artifact removal in scalp EEG measurements

    Science.gov (United States)

    Kilicarslan, Atilla; Grossman, Robert G.; Contreras-Vidal, Jose Luis

    2016-04-01

    Objective. Non-invasive measurement of human neural activity based on the scalp electroencephalogram (EEG) allows for the development of biomedical devices that interface with the nervous system for scientific, diagnostic, therapeutic, or restorative purposes. However, EEG recordings are often considered as prone to physiological and non-physiological artifacts of different types and frequency characteristics. Among them, ocular artifacts and signal drifts represent major sources of EEG contamination, particularly in real-time closed-loop brain-machine interface (BMI) applications, which require effective handling of these artifacts across sessions and in natural settings. Approach. We extend the usage of a robust adaptive noise cancelling (ANC) scheme ({H}∞ filtering) for removal of eye blinks, eye motions, amplitude drifts and recording biases simultaneously. We also characterize the volume conduction, by estimating the signal propagation levels across all EEG scalp recording areas due to ocular artifact generators. We find that the amplitude and spatial distribution of ocular artifacts vary greatly depending on the electrode location. Therefore, fixed filtering parameters for all recording areas would naturally hinder the true overall performance of an ANC scheme for artifact removal. We treat each electrode as a separate sub-system to be filtered, and without the loss of generality, they are assumed to be uncorrelated and uncoupled. Main results. Our results show over 95-99.9% correlation between the raw and processed signals at non-ocular artifact regions, and depending on the contamination profile, 40-70% correlation when ocular artifacts are dominant. We also compare our results with the offline independent component analysis and artifact subspace reconstruction methods, and show that some local quantities are handled better by our sample-adaptive real-time framework. Decoding performance is also compared with multi-day experimental data from 2 subjects

  11. Ultrasound-guided probe-generated artifacts stimulating ventricular tachycardia: A rare phenomenon

    Directory of Open Access Journals (Sweden)

    Rafat Shamim

    2017-01-01

    Full Text Available Electrocardiographic (ECG artifacts may arise due to interference, faulty earthing, and current leakages in biomedical equipment which might create clinical dilemmas in the perioperative settings. Piezoelectric signals generated by ultrasonography probe are another uncommon source which might be sensed by the ECG electrodes and produce tracings similar to pathological arrhythmias triggering false alarms and avoidable therapies. Anesthesiologists should be familiar with these uncommon sources which might produce these artifacts and they should be identified swiftly.

  12. Comparison of ring artifact removal methods using flat panel detector based CT images

    OpenAIRE

    2011-01-01

    Abstract Background Ring artifacts are the concentric rings superimposed on the tomographic images often caused by the defective and insufficient calibrated detector elements as well as by the damaged scintillator crystals of the flat panel detector. It may be also generated by objects attenuating X-rays very differently in different projection direction. Ring artifact reduction techniques so far reported in the literature can be broadly classified into two groups. One category of the approac...

  13. Computer Science Approach to Information-Like Artifacts as Exemplified by Memes

    OpenAIRE

    Sabah Al-Fedaghi

    2015-01-01

    Providing information can be expanded to include systems that deliver information-like artifacts. They provide such “things” as advertisements, propaganda pieces, and meme artifacts. Memes are the subject of extensive intellectual debate in science and popular culture because it is claimed that parallels can be drawn between theories of cultural evolution manifested in memes, and theories of biological evolution. Memes are described as self-reproducing mental structures, intangible entities t...

  14. A Cross-Device Spatial Workspace Supporting Artifact-Mediated Collaboration in Interaction Design

    OpenAIRE

    Geyer, Florian; Reiterer, Harald

    2010-01-01

    In this paper we present our approach to support artifact-mediated collaboration in interaction design. We argue that the extensive number and the diversity of artifacts created and reflected upon during collaborative design activities as well as transitions between physical and digital representations impose both a challenge and opportunity for supporting interaction design practice. The design principles for our experimental tool that we introduce within this paper are based on a cross-devi...

  15. The Tromsø Study: artifacts in forearm bone densitometry--prevalence and effect.

    Science.gov (United States)

    Berntsen, G K; Tollan, A; Magnus, J H; Søgaard, A J; Ringberg, T; Fønnebø, V

    1999-01-01

    Suboptimal performance of bone densitometer, operator and/or subject may cause artifacts of consequence both for individual patient management and research. The prevalence and effects of such artifacts are largely unknown in densitometry. A cross-sectional population-based study was carried out of artifacts in forearm bone densitometry with single X-ray Absorptiometry (SXA) of the nondominant hand (distal and ultradistal site). After the screening, all scans were reviewed for artifact detection and reanalysis. The effect on the bone mineral density (BMD) result was found by comparing artifactual scans with a reanalyzed version or with normal repeat scans. All women aged 50-74 years, all men aged 55-74 years and 5-10% samples of other age groups aged >/=25 years attending the fourth Tromso health study were invited to have bone densitometry. The response rate from the background population was 80% (n = 7948). Fourteen percent of subjects had a movement artifact at either the distal or ultradistal site. The individual BMD variation was twice as large in scans with a movement artifact (0.94%) compared with normal scans (0.58%) (p = 0.0027). The radial endplate was inaccurately detected in 74% of the scans. Reanalysis of these scans led to a mean 3.8% decrease in the BMD value and an increase in the prevalence of osteoporosis of 10%. Artifacts were thus common, and their effects were clinically relevant in forearm bone densitometry. Artifacts and their effects need to be characterized in other bone densitometry settings also.

  16. The effects of side-artifacts on the elastic modulus of trabecular bone.

    Science.gov (United States)

    Un, Kerem; Bevill, Grant; Keaveny, Tony M

    2006-01-01

    Determining accurate density-mechanical property relationships for trabecular bone is critical for correct characterization of this important structure-function relation. When testing any excised specimen of trabecular bone, an unavoidable experimental artifact originates from the sides of the specimen where peripheral trabeculae lose their vertical load-bearing capacity due to interruption of connectivity, a phenomenon denoted here as the 'side-artifact'. We sought in this study to quantify the magnitude of such side-artifact errors in modulus measurement and to do so as a function of the trabecular architecture and specimen size. Using parametric computational analysis of high-resolution micro-CT-based finite-element models of cores of elderly human vertebral trabecular bone, a specimen-specific correction factor for the side-artifact was quantified as the ratio of the side-artifact-free apparent modulus (Etrue) to the apparent modulus that would be measured in a typical experiment (Emeasured). We found that the width over which the peripheral trabeculae were mostly unloaded was between 0.19 and 0.58 mm. The side-artifact led to an underestimation error in Etrue of over 50% in some specimens, having a mean (+/-SD) of 27+/-11%. There was a trend for the correction factor to linearly increase as volume fraction decreased (p=0.001) and as mean trabecular separation increased (perror increased substantially as specimen size decreased. Two methods used for correcting for the side-artifact were both successful in bringing Emeasured into statistical agreement with Etrue. These findings have important implications for the interpretation of almost all literature data on trabecular bone mechanical properties since they indicate that such properties need to be adjusted to eliminate the substantial effects of side-artifacts in order to provide more accurate estimates of in situ behavior.

  17. Ultrasound-guided probe-generated artifacts stimulating ventricular tachycardia: A rare phenomenon

    Science.gov (United States)

    Shamim, Rafat; Haldar, Rudrashish; Kaushal, Ashutosh

    2017-01-01

    Electrocardiographic (ECG) artifacts may arise due to interference, faulty earthing, and current leakages in biomedical equipment which might create clinical dilemmas in the perioperative settings. Piezoelectric signals generated by ultrasonography probe are another uncommon source which might be sensed by the ECG electrodes and produce tracings similar to pathological arrhythmias triggering false alarms and avoidable therapies. Anesthesiologists should be familiar with these uncommon sources which might produce these artifacts and they should be identified swiftly. PMID:28217063

  18. Computer Science Approach to Information-Like Artifacts as Exemplified by Memes

    OpenAIRE

    Sabah Al-Fedaghi

    2015-01-01

    Providing information can be expanded to include systems that deliver information-like artifacts. They provide such “things” as advertisements, propaganda pieces, and meme artifacts. Memes are the subject of extensive intellectual debate in science and popular culture because it is claimed that parallels can be drawn between theories of cultural evolution manifested in memes, and theories of biological evolution. Memes are described as self-reproducing mental structures, intangible entities t...

  19. MRI-Based Computed Tomography Metal Artifact Correction Method for Improving Proton Range Calculation Accuracy

    Energy Technology Data Exchange (ETDEWEB)

    Park, Peter C. [Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Schreibmann, Eduard; Roper, Justin; Elder, Eric; Crocker, Ian [Department of Radiation Oncology, Winship Cancer Institute of Emory University, Atlanta, Georgia (United States); Fox, Tim [Varian Medical Systems, Palo Alto, California (United States); Zhu, X. Ronald [Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Dong, Lei [Scripps Proton Therapy Center, San Diego, California (United States); Dhabaan, Anees, E-mail: anees.dhabaan@emory.edu [Department of Radiation Oncology, Winship Cancer Institute of Emory University, Atlanta, Georgia (United States)

    2015-03-15

    Purpose: Computed tomography (CT) artifacts can severely degrade dose calculation accuracy in proton therapy. Prompted by the recently increased popularity of magnetic resonance imaging (MRI) in the radiation therapy clinic, we developed an MRI-based CT artifact correction method for improving the accuracy of proton range calculations. Methods and Materials: The proposed method replaces corrupted CT data by mapping CT Hounsfield units (HU number) from a nearby artifact-free slice, using a coregistered MRI. MRI and CT volumetric images were registered with use of 3-dimensional (3D) deformable image registration (DIR). The registration was fine-tuned on a slice-by-slice basis by using 2D DIR. Based on the intensity of paired MRI pixel values and HU from an artifact-free slice, we performed a comprehensive analysis to predict the correct HU for the corrupted region. For a proof-of-concept validation, metal artifacts were simulated on a reference data set. Proton range was calculated using reference, artifactual, and corrected images to quantify the reduction in proton range error. The correction method was applied to 4 unique clinical cases. Results: The correction method resulted in substantial artifact reduction, both quantitatively and qualitatively. On respective simulated brain and head and neck CT images, the mean error was reduced from 495 and 370 HU to 108 and 92 HU after correction. Correspondingly, the absolute mean proton range errors of 2.4 cm and 1.7 cm were reduced to less than 2 mm in both cases. Conclusions: Our MRI-based CT artifact correction method can improve CT image quality and proton range calculation accuracy for patients with severe CT artifacts.

  20. To Help Rural Students Achieve"University Dream":Interpreting"Uselessness of Study Theory"from the Perspective of Labor Economics"%拨云散雾,助农村学生圆“大学梦”--从劳动经济学视角解读当代大学生“读书无用论”

    Institute of Scientific and Technical Information of China (English)

    杜鸣

    2014-01-01

    本文将从劳动经济学视角,应用人力资源价值计量及人力成本理论对大学生“读书无用论”的影响进行科学分析,寻求产生此观念的根源,并提出解决策略。%This paper scientifically analyzes the influence of human resources value measurement and labor cost theory on"Uselessness of Study Theory", and tries to find the origin of this concept, then proposes the solution strategy.

  1. MR imaging artifacts and parallel imaging techniques with calibration scanning: a new twist on old problems.

    Science.gov (United States)

    Yanasak, Nathan E; Kelly, Michael J

    2014-01-01

    The application of parallel magnetic resonance (MR) imaging is increasing as clinicians continue to strive for improved spatial and temporal resolution, benefits that arise from the use of fewer phase encodings during imaging. To reconstruct images, extra information is needed to map the spatial sensitivity of each coil element, which may be accomplished by acquiring a calibration image in one common implementation of parallel MR imaging. Although obtaining a quick calibration image is an efficient method for gathering this information, corruption of the image or disharmony with subsequent images may lead to errors in reconstruction. Although conventional MR imaging sequences may be employed with parallel MR imaging, the altered image reconstruction introduces several new artifacts and changes the appearance of conventional artifacts. The altered appearance of traditional artifacts may obscure the source of the problem, and, in some cases, the severity of artifacts associated with parallel MR imaging may be exacerbated, hindering image interpretation. Several artifacts arise in the context of parallel MR imaging, including both traditional artifacts and those associated with parallel MR imaging.

  2. How measurement artifacts affect cerebral autoregulation outcomes: A technical note on transfer function analysis.

    Science.gov (United States)

    Meel-van den Abeelen, Aisha S S; de Jong, Daan L K; Lagro, Joep; Panerai, Ronney B; Claassen, Jurgen A H R

    2016-05-01

    Cerebral autoregulation (CA) is the mechanism that aims to maintain adequate cerebral perfusion during changes in blood pressure (BP). Transfer function analysis (TFA), the most reported method in literature to quantify CA, shows large between-study variability in outcomes. The aim of this study is to investigate the role of measurement artifacts in this variation. Specifically, the role of distortion in the BP and/or CBFV measurementon TFA outcomes was investigated. The influence of three types of artifacts on TFA outcomes was studied: loss of signal, motion artifacts, and baseline drifts. TFA metrics of signals without the simulated artifacts were compared with those of signals with artifacts. TFA outcomes scattered highly when more than 10% of BP signal or over 8% of the CBFV signal was lost, or when measurements contained one or more artifacts resulting from head movement. Furthermore, baseline drift affected interpretation of TFA outcomes when the power in the BP signal was 5 times the power in the LF band. In conclusion, loss of signal in BP and loss in CBFV, affects interpretation of TFA outcomes. Therefore, it is vital to validate signal quality to the defined standards before interpreting TFA outcomes.

  3. MARSAME Radiological Release Report for Archaeological Artifacts Excavated from Area L

    Energy Technology Data Exchange (ETDEWEB)

    Ruedig, Elizabeth [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Whicker, Jeffrey Jay [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Gillis, Jessica Mcdonnel [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-06-03

    In 1991 Los Alamos National Laboratory’s (LANL’s) cultural resources team excavated archaeological site LA 4618 located at Technical Area 54, within Material Disposal Area L (MDA L). MDA L received non-radioactive chemical waste from the early 1960s until 1985. Further development of the MDA required excavation of several cultural sites under National Historic Preservation Act requirements; artifacts from these sites have been subsequently stored at LANL. The LANL cultural resources group would now like to release these artifacts to the Museum of Indian Arts and Culture in Santa Fe for curation. The history of disposal at Area L suggests that the artifact pool is unlikely to be chemically contaminated and LANL staff washed each artifact at least once following excavation. Thus, it is unlikely that the artifacts present a chemical hazard. LANL’s Environmental Stewardship group (EPC-ES) has evaluated the radiological survey results for the Area L artifact pool and found that the items described in this report meet the criteria for unrestricted radiological release under Department of Energy (DOE) Order 458.1 Radiation Protection of the Public and the Environment and are candidates for release without restriction from LANL control. This conclusion is based on the known history of MDA L and on radiation survey data.

  4. Automated EEG artifact elimination by applying machine learning algorithms to ICA-based features

    Science.gov (United States)

    Radüntz, Thea; Scouten, Jon; Hochmuth, Olaf; Meffert, Beate

    2017-08-01

    Objective. Biological and non-biological artifacts cause severe problems when dealing with electroencephalogram (EEG) recordings. Independent component analysis (ICA) is a widely used method for eliminating various artifacts from recordings. However, evaluating and classifying the calculated independent components (IC) as artifact or EEG is not fully automated at present. Approach. In this study, we propose a new approach for automated artifact elimination, which applies machine learning algorithms to ICA-based features. Main results. We compared the performance of our classifiers with the visual classification results given by experts. The best result with an accuracy rate of 95% was achieved using features obtained by range filtering of the topoplots and IC power spectra combined with an artificial neural network. Significance. Compared with the existing automated solutions, our proposed method is not limited to specific types of artifacts, electrode configurations, or number of EEG channels. The main advantages of the proposed method is that it provides an automatic, reliable, real-time capable, and practical tool, which avoids the need for the time-consuming manual selection of ICs during artifact removal.

  5. Computed tomography of kidney with diuretics. A method for avoiding artifact due to nonionic contrast medium

    Energy Technology Data Exchange (ETDEWEB)

    Hiromura, Tadao; Terae, Satoshi; Takamura, Akio; Mizoe, Junetsu (Obihiro Kosei Hospital, Hokkaido (Japan)); Morita, Yutaka; Irie, Goro

    1989-07-01

    We devised a method for avoiding beam-hardening artifacts, which interfere with enhanced CT images of kidney due to nonionic contrast medium. The radiographic effect and the frequency of beam-hardening artifacts on enhanced CT of kidney were studied by prospective comparison among three groups: a group of 20 patients examined with furosemide (f-d.CT), a group of 20 patients examined without diuretics (non-d.CT) and a group of 20 patients examined after water intake (w-d.CT). In all patients of f-d.CT group, the renal parenchyma from the cortex to the papilla was almost evently enhanced, free from artifacts. The density of the renal papilla and pelvis in non-d.CT and w-d.CT groups was significantly higher than that in f-d.CT group, and artifacts were also observed in 14 (70%) of non-d.CT group and 12 (60%) of w.d.CT group, respectively. Satisfactory CT of kidney free from artifacts was obtained by f-d.CT, providing easy evaluation of renal pelvic or peripelvic lesions. In conclusion, this technique can be used in those pathologic cases of renal pelvis or peripelvic region, that are not clear on routine CT because of artifacts. (author).

  6. Correct block artifacts by differential projection for a dynamic computed tomography system

    Science.gov (United States)

    Xiao, Yongshun; Han, Fangda; Chen, Zhiqiang

    2017-09-01

    In the aero-engine industry, it is important to carry out regular and effective tests on engines in service. However, current detection methods often have problems such as a limitation on materials characteristics or geometry structures. Recently, a novel dynamic computed tomography (CT) system was proposed to provide highly efficient CT inspection for rotating parts, in particular the blades of aero-engines in operation. However, one problem exists in the proposed system in that some components remain static when the engine is in operation. These static parts will appear as strip artifacts in projection and ultimately as ring artifacts in the reconstructed image, which are called block artifacts. In this paper, we put forward a differential projection correction method to correct block artifacts and reconstruct the blades of the aero-engine. The method makes use of the distribution of the blades and the static parts to remove the artifacts. The experiment results show that the proposed method can effectively remove the block artifacts while maintaining the grayscale and geometry structure of the blades, furthermore, we also verify its ability to detect defects using numerical experiments. The differential projection correction method makes the system more practicable for in situ inspection of aero-engines.

  7. Metal artifact reduction using a patch-based reconstruction for digital breast tomosynthesis

    Science.gov (United States)

    Borges, Lucas R.; Bakic, Predrag R.; Maidment, Andrew D. A.; Vieira, Marcelo A. C.

    2017-03-01

    Digital breast tomosynthesis (DBT) is rapidly emerging as the main clinical tool for breast cancer screening. Although several reconstruction methods for DBT are described by the literature, one common issue is the interplane artifacts caused by out-of-focus features. For breasts containing highly attenuating features, such as surgical clips and large calcifications, the artifacts are even more apparent and can limit the detection and characterization of lesions by the radiologist. In this work, we propose a novel method of combining backprojected data into tomographic slices using a patch-based approach, commonly used in denoising. Preliminary tests were performed on a geometry phantom and on an anthropomorphic phantom containing metal inserts. The reconstructed images were compared to a commercial reconstruction solution. Qualitative assessment of the reconstructed images provides evidence that the proposed method reduces artifacts while maintaining low noise levels. Objective assessment supports the visual findings. The artifact spread function shows that the proposed method is capable of suppressing artifacts generated by highly attenuating features. The signal difference to noise ratio shows that the noise levels of the proposed and commercial methods are comparable, even though the commercial method applies post-processing filtering steps, which were not implemented on the proposed method. Thus, the proposed method can produce tomosynthesis reconstructions with reduced artifacts and low noise levels.

  8. Dual energy CT: How well can pseudo-monochromatic imaging reduce metal artifacts?

    Energy Technology Data Exchange (ETDEWEB)

    Kuchenbecker, Stefan, E-mail: stefan.kuchenbecker@dkfz.de; Faby, Sebastian; Sawall, Stefan; Kachelrieß, Marc [German Cancer Research Center (DKFZ), Heidelberg 69120 (Germany); Lell, Michael [Friedrich-Alexander-University (FAU), Erlangen 91054 (Germany)

    2015-02-15

    Purpose: Dual Energy CT (DECT) provides so-called monoenergetic images based on a linear combination of the original polychromatic images. At certain patient-specific energy levels, corresponding to certain patient- and slice-dependent linear combination weights, e.g., E = 160 keV corresponds to α = 1.57, a significant reduction of metal artifacts may be observed. The authors aimed at analyzing the method for its artifact reduction capabilities to identify its limitations. The results are compared with raw data-based processing. Methods: Clinical DECT uses a simplified version of monochromatic imaging by linearly combining the low and the high kV images and by assigning an energy to that linear combination. Those pseudo-monochromatic images can be used by radiologists to obtain images with reduced metal artifacts. The authors analyzed the underlying physics and carried out a series expansion of the polychromatic attenuation equations. The resulting nonlinear terms are responsible for the artifacts, but they are not linearly related between the low and the high kV scan: A linear combination of both images cannot eliminate the nonlinearities, it can only reduce their impact. Scattered radiation yields additional noncanceling nonlinearities. This method is compared to raw data-based artifact correction methods. To quantify the artifact reduction potential of pseudo-monochromatic images, they simulated the FORBILD abdomen phantom with metal implants, and they assessed patient data sets of a clinical dual source CT system (100, 140 kV Sn) containing artifacts induced by a highly concentrated contrast agent bolus and by metal. In each case, they manually selected an optimal α and compared it to a raw data-based material decomposition in case of simulation, to raw data-based material decomposition of inconsistent rays in case of the patient data set containing contrast agent, and to the frequency split normalized metal artifact reduction in case of the metal

  9. Phylogenetic mixture models can reduce node-density artifacts.

    Science.gov (United States)

    Venditti, Chris; Meade, Andrew; Pagel, Mark

    2008-04-01

    We investigate the performance of phylogenetic mixture models in reducing a well-known and pervasive artifact of phylogenetic inference known as the node-density effect, comparing them to partitioned analyses of the same data. The node-density effect refers to the tendency for the amount of evolutionary change in longer branches of phylogenies to be underestimated compared to that in regions of the tree where there are more nodes and thus branches are typically shorter. Mixture models allow more than one model of sequence evolution to describe the sites in an alignment without prior knowledge of the evolutionary processes that characterize the data or how they correspond to different sites. If multiple evolutionary patterns are common in sequence evolution, mixture models may be capable of reducing node-density effects by characterizing the evolutionary processes more accurately. In gene-sequence alignments simulated to have heterogeneous patterns of evolution, we find that mixture models can reduce node-density effects to negligible levels or remove them altogether, performing as well as partitioned analyses based on the known simulated patterns. The mixture models achieve this without knowledge of the patterns that generated the data and even in some cases without specifying the full or true model of sequence evolution known to underlie the data. The latter result is especially important in real applications, as the true model of evolution is seldom known. We find the same patterns of results for two real data sets with evidence of complex patterns of sequence evolution: mixture models substantially reduced node-density effects and returned better likelihoods compared to partitioning models specifically fitted to these data. We suggest that the presence of more than one pattern of evolution in the data is a common source of error in phylogenetic inference and that mixture models can often detect these patterns even without prior knowledge of their presence in the

  10. Artifact-based reflective interviews for identifying pragmatic epistemological resources

    Science.gov (United States)

    Shubert, Christopher Walden

    Physics Education Research studies the science of teaching and learning physics. The process of student learning is complex, and the factors that affect it are numerous. Describing students' understanding of physics knowledge and reasoning is the basis for much productive research; however, such research fails to account for certain types of student learning difficulties. In this dissertation, I explore one source of student difficulty: personal epistemology, students' ideas about knowledge and knowing. Epistemology traditionally answers three questions: What is knowledge? How is knowledge created? And, how do we know what we know? An individual's responses to these questions can affect learning in terms of how they approach tasks involving the construction and application of knowledge. The key issue addressed in this dissertation is the effect of methodological choices on the validity and reliability of claims concerning personal epistemology. My central concern is contextual validity, how what is said about one's epistemology is not identical to how one behaves epistemologically. In response to these issues, I present here a new methodology for research on student epistemology: video artifact-based reflective interview protocols. These protocols begin with video taping students in their natural classroom activities, and then asking the participants epistemological questions immediately after watching selected scenes from their activity, contextually anchoring them in their actual learning experience. The data from these interviews is viewed in the framework of Epistemological Resource Theory, a framework of small bits of knowledge whose coordination in a given context is used to describe personal epistemology. I claim that the privileged data from these interviews allows detailed epistemological resources to be identified, and that these resources can provide greater insight into how student epistemologies are applied in learning activities. This research

  11. Using Internet Artifacts to Profile a Child Pornography Suspect

    Directory of Open Access Journals (Sweden)

    Marcus K. Rogers

    2014-03-01

    behavioral analysis process described, but the ability to infer the predilection for being a consumer of child pornography based on Internet artifacts may prove to be a powerful tool for investigators.

  12. Hydrophobic fluorescent probes introduce artifacts into single molecule tracking experiments due to non-specific binding.

    Science.gov (United States)

    Zanetti-Domingues, Laura C; Tynan, Christopher J; Rolfe, Daniel J; Clarke, David T; Martin-Fernandez, Marisa

    2013-01-01

    Single-molecule techniques are powerful tools to investigate the structure and dynamics of macromolecular complexes; however, data quality can suffer because of weak specific signal, background noise and dye bleaching and blinking. It is less well-known, but equally important, that non-specific binding of probe to substrates results in a large number of immobile fluorescent molecules, introducing significant artifacts in live cell experiments. Following from our previous work in which we investigated glass coating substrates and demonstrated that the main contribution to this non-specific probe adhesion comes from the dye, we carried out a systematic investigation of how different dye chemistries influence the behaviour of spectrally similar fluorescent probes. Single-molecule brightness, bleaching and probe mobility on the surface of live breast cancer cells cultured on a non-adhesive substrate were assessed for anti-EGFR affibody conjugates with 14 different dyes from 5 different manufacturers, belonging to 3 spectrally homogeneous bands (491 nm, 561 nm and 638 nm laser lines excitation). Our results indicate that, as well as influencing their photophysical properties, dye chemistry has a strong influence on the propensity of dye-protein conjugates to adhere non-specifically to the substrate. In particular, hydrophobicity has a strong influence on interactions with the substrate, with hydrophobic dyes showing much greater levels of binding. Crucially, high levels of non-specific substrate binding result in calculated diffusion coefficients significantly lower than the true values. We conclude that the physic-chemical properties of the dyes should be considered carefully when planning single-molecule experiments. Favourable dye characteristics such as photostability and brightness can be offset by the propensity of a conjugate for non-specific adhesion.

  13. Hydrophobic fluorescent probes introduce artifacts into single molecule tracking experiments due to non-specific binding.

    Directory of Open Access Journals (Sweden)

    Laura C Zanetti-Domingues

    Full Text Available Single-molecule techniques are powerful tools to investigate the structure and dynamics of macromolecular complexes; however, data quality can suffer because of weak specific signal, background noise and dye bleaching and blinking. It is less well-known, but equally important, that non-specific binding of probe to substrates results in a large number of immobile fluorescent molecules, introducing significant artifacts in live cell experiments. Following from our previous work in which we investigated glass coating substrates and demonstrated that the main contribution to this non-specific probe adhesion comes from the dye, we carried out a systematic investigation of how different dye chemistries influence the behaviour of spectrally similar fluorescent probes. Single-molecule brightness, bleaching and probe mobility on the surface of live breast cancer cells cultured on a non-adhesive substrate were assessed for anti-EGFR affibody conjugates with 14 different dyes from 5 different manufacturers, belonging to 3 spectrally homogeneous bands (491 nm, 561 nm and 638 nm laser lines excitation. Our results indicate that, as well as influencing their photophysical properties, dye chemistry has a strong influence on the propensity of dye-protein conjugates to adhere non-specifically to the substrate. In particular, hydrophobicity has a strong influence on interactions with the substrate, with hydrophobic dyes showing much greater levels of binding. Crucially, high levels of non-specific substrate binding result in calculated diffusion coefficients significantly lower than the true values. We conclude that the physic-chemical properties of the dyes should be considered carefully when planning single-molecule experiments. Favourable dye characteristics such as photostability and brightness can be offset by the propensity of a conjugate for non-specific adhesion.

  14. Combining EEG and eye tracking: Identification, characterization and correction of eye movement artifacts in electroencephalographic data

    Directory of Open Access Journals (Sweden)

    Michael ePlöchl

    2012-10-01

    Full Text Available Eye movements introduce large artifacts to electroencephalographic recordings (EEG and thus render data analysis difficult or even impossible. Trials contaminated by eye movement and blink artifacts have to be discarded, hence in standard EEG-paradigms subjects are required to fixate on the screen. To overcome this restriction, several correction methods including regression and blind source separation have been proposed. Yet, there is no automated standard procedure established. By simultaneously recording eye movements and 64-channel-EEG during a guided eye movement paradigm, we show that eye movement artifacts consist of several components, which arise from different sources. These include corneo-retinal dipole changes, saccadic spike potentials and eyelid movements. Moreover, we demonstrate that depending on electrode site, gaze direction and choice of reference these components contribute differently to the measured signal. Therefore they cannot be removed by regression-based correction methods, as these inevitably over- or under-correct individual artifact components. Finally we propose a correction procedure based on Independent Component Analysis (ICA. This procedure uses eye tracker information to reliably and objectively identify eye-artifact related ICA-components in an automated manner. We demonstrate that this approach allows removing or substantially reducing ocular artifacts including microsaccades without affecting the signal originating from brain sources. In conclusion the proposed method does not only provide a tool for detecting and correcting eye artifacts in standard EEG-paradigms but it also permits to study EEG-activity during eye tracking experiments and thus to investigate neural mechanisms of eye movement control and visual attention under natural conditions.

  15. Reference layer adaptive filtering (RLAF) for EEG artifact reduction in simultaneous EEG-fMRI

    Science.gov (United States)

    Steyrl, David; Krausz, Gunther; Koschutnig, Karl; Edlinger, Günter; Müller-Putz, Gernot R.

    2017-04-01

    Objective. Simultaneous electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) combines advantages of both methods, namely high temporal resolution of EEG and high spatial resolution of fMRI. However, EEG quality is limited due to severe artifacts caused by fMRI scanners. Approach. To improve EEG data quality substantially, we introduce methods that use a reusable reference layer EEG cap prototype in combination with adaptive filtering. The first method, reference layer adaptive filtering (RLAF), uses adaptive filtering with reference layer artifact data to optimize artifact subtraction from EEG. In the second method, multi band reference layer adaptive filtering (MBRLAF), adaptive filtering is performed on bandwidth limited sub-bands of the EEG and the reference channels. Main results. The results suggests that RLAF outperforms the baseline method, average artifact subtraction, in all settings and also its direct predecessor, reference layer artifact subtraction (RLAS), in lower (mean-square voltage reduction and power reduction of EEG provided that physiological EEG components such as occipital EEG alpha power and visual evoked potentials (VEP) are preserved. We demonstrate that both, RLAF and MBRLAF, improve VEP quality. For that, we calculate the mean-squared-distance of single trial VEP to the mean VEP and estimate single trial VEP classification accuracies. We found that the average mean-squared-distance is lowest and the average classification accuracy is highest after MBLAF. RLAF was second best. Significance. In conclusion, the results suggests that RLAF and MBRLAF are potentially very effective in improving EEG quality of simultaneous EEG-fMRI. Highlights We present a new and reusable reference layer cap prototype for simultaneous EEG-fMRI We introduce new algorithms for reducing EEG artifacts due to simultaneous fMRI The algorithms combine a reference layer and adaptive filtering Several evaluation criteria suggest superior

  16. Stimulation artifact correction method for estimation of early cortico-cortical evoked potentials.

    Science.gov (United States)

    Trebaul, Lena; Rudrauf, David; Job, Anne-Sophie; Mălîia, Mihai Dragos; Popa, Irina; Barborica, Andrei; Minotti, Lorella; Mîndruţă, Ioana; Kahane, Philippe; David, Olivier

    2016-05-01

    Effective connectivity can be explored using direct electrical stimulations in patients suffering from drug-resistant focal epilepsies and investigated with intracranial electrodes. Responses to brief electrical pulses mimic the physiological propagation of signals and manifest as cortico-cortical evoked potentials (CCEP). The first CCEP component is believed to reflect direct connectivity with the stimulated region but the stimulation artifact, a sharp deflection occurring during a few milliseconds, frequently contaminates it. In order to recover the characteristics of early CCEP responses, we developed an artifact correction method based on electrical modeling of the electrode-tissue interface. The biophysically motivated artifact templates are then regressed out of the recorded data as in any classical template-matching removal artifact methods. Our approach is able to make the distinction between the physiological responses time-locked to the stimulation pulses and the non-physiological component. We tested the correction on simulated CCEP data in order to quantify its efficiency for different stimulation and recording parameters. We demonstrated the efficiency of the new correction method on simulations of single trial recordings for early responses contaminated with the stimulation artifact. The results highlight the importance of sampling frequency for an accurate analysis of CCEP. We then applied the approach to experimental data. The model-based template removal was compared to a correction based on the subtraction of the averaged artifact. This new correction method of stimulation artifact will enable investigators to better analyze early CCEP components and infer direct effective connectivity in future CCEP studies. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  17. Correction of motion artifacts in OCT-AFI data collected in airways (Conference Presentation)

    Science.gov (United States)

    Abouei, Elham; Lane, Pierre M.; Pahlevaninezhad, Hamid; Lee, Anthony; Lam, Stephen; MacAulay, Calum E.

    2016-03-01

    Abstract: Optical coherence tomography (OCT) provides in vivo imaging with near-histologic resolution of tissue morphology. OCT has been successfully employed in clinical practice in non-pulmonary fields of medicine such as ophthalmology and cardiology. Studies suggest that OCT has the potential to be a powerful tool for the detection and localization of malignant and non-malignant pulmonary diseases. The combination of OCT with autofluorescence imaging (AFI) provides valuable information about the structural and metabolic state of tissues. Successful application of OCT or OCT-AFI to the field of pulmonary medicine requires overcoming several challenges. This work address those associated with motion: cardiac cycle, breathing and non-uniform rotation distortion (NURD) artifacts. Mechanically rotated endoscopic probes often suffer from image degradation due to NURD. In addition cardiac and breathing motion artifacts may be present in-vivo that are not seen ex-vivo. These motion artifacts can be problematic in OCT-AFI systems with slower acquisition rates and have been observed to generate identifiable prominent artifacts which make confident interpretation of observed structures (blood vessels, etc) difficult. Understanding and correcting motion artifact could improve the image quality and interpretation. In this work, the motion artifacts in pulmonary OCT-AFI data sets are estimated in both AFI and OCT images using a locally adaptive registration algorithm that can be used to correct/reduce such artifacts. Performance of the algorithm is evaluated on images of a NURD phantom and on in-vivo OCT-AFI datasets of peripheral lung airways.

  18. Beam hardening and motion artifacts in cardiac CT: evaluation and iterative correction method

    Science.gov (United States)

    Shen, Zeyang; Lee, Okkyun; Taguchi, Katsuyuki

    2016-03-01

    For myocardial perfusion CT exams, beam hardening (BH) artifacts may degrade the accuracy of myocardial perfusion defect detection. Meanwhile, cardiac motion may make BH process inconsistent, which makes conventional BH correction (BHC) methods ineffective. The aims of this study were to assess the severity of BH artifacts and motion artifacts and propose a projection-based iterative BHC method which has a potential to handle the motion-induced inconsistency better than conventional methods. In this study, four sets of forward projection data were first acquired using both cylindrical phantoms and cardiac images as objects: (1) with monochromatic x-rays without motion; (2) with polychromatic x-rays without motion; (3) with monochromatic x-rays with motion; and (4) with polychromatic x-rays with motion. From each dataset, images were reconstructed using filtered back projection; for datasets 2 and 4, one of the following BHC methods was also performed: (A) no BHC; (B) BHC that concerns water only; and (C) BHC that takes both water and iodine into account, which is an iterative method we developed in this work. Biases of images were quantified by the mean absolute difference (MAD). The MAD of images with BH artifacts alone (dataset 2, without BHC) was comparable or larger than that of images with motion artifacts alone (dataset 3): In the study of cardiac image, BH artifacts account for over 80% of the total artifacts. The use of BHC was effective: with dataset 4, MAD values were 170 HU with no BHC, 54 HU with water BHC, and 42 HU with the proposed BHC. Qualitative improvements in image quality were also noticeable in reconstructed images.

  19. The effects of transducer geometry on artifacts common to diagnostic bone imaging with conventional medical ultrasound.

    Science.gov (United States)

    Mauldin, F William; Owen, Kevin; Tiouririne, Mohamed; Hossack, John A

    2012-06-01

    The portability, low cost, and non-ionizing radiation associated with medical ultrasound suggest that it has potential as a superior alternative to X-ray for bone imaging. However, when conventional ultrasound imaging systems are used for bone imaging, clinical acceptance is frequently limited by artifacts derived from reflections occurring away from the main axis of the acoustic beam. In this paper, the physical source of off-axis artifacts and the effect of transducer geometry on these artifacts are investigated in simulation and experimental studies. In agreement with diffraction theory, the sampled linear-array geometry possessed increased off-axis energy compared with single-element piston geometry, and therefore, exhibited greater levels of artifact signal. Simulation and experimental results demonstrated that the linear-array geometry exhibited increased artifact signal when the center frequency increased, when energy off-axis to the main acoustic beam (i.e., grating lobes) was perpendicularly incident upon off-axis surfaces, and when off-axis surfaces were specular rather than diffusive. The simulation model used to simulate specular reflections was validated experimentally and a correlation coefficient of 0.97 between experimental and simulated peak reflection contrast was observed. In ex vivo experiments, the piston geometry yielded 4 and 6.2 dB average contrast improvement compared with the linear array when imaging the spinous process and interlaminar space of an animal spine, respectively. This work indicates that off-axis reflections are a major source of ultrasound image artifacts, particularly in environments comprising specular reflecting (i.e., bone or bone-like) objects. Transducer geometries with reduced sensitivity to off-axis surface reflections, such as a piston transducer geometry, yield significant reductions in image artifact.

  20. Body MRI artifacts in clinical practice: a physicist's and radiologist's perspective.

    Science.gov (United States)

    Graves, Martin J; Mitchell, Donald G

    2013-08-01

    The high information content of MRI exams brings with it unintended effects, which we call artifacts. The purpose of this review is to promote understanding of these artifacts, so they can be prevented or properly interpreted to optimize diagnostic effectiveness. We begin by addressing static magnetic field uniformity, which is essential for many techniques, such as fat saturation. Eddy currents, resulting from imperfect gradient pulses, are especially problematic for new techniques that depend on high performance gradient switching. Nonuniformity of the transmit radiofrequency system constitutes another source of artifacts, which are increasingly important as magnetic field strength increases. Defects in the receive portion of the radiofrequency system have become a more complex source of problems as the number of radiofrequency coils, and the sophistication of the analysis of their received signals, has increased. Unwanted signals and noise spikes have many causes, often manifesting as zipper or banding artifacts. These image alterations become particularly severe and complex when they are combined with aliasing effects. Aliasing is one of several phenomena addressed in our final section, on artifacts that derive from encoding the MR signals to produce images, also including those related to parallel imaging, chemical shift, motion, and image subtraction.

  1. Motion artifacts in MRI: A complex problem with many partial solutions.

    Science.gov (United States)

    Zaitsev, Maxim; Maclaren, Julian; Herbst, Michael

    2015-10-01

    Subject motion during magnetic resonance imaging (MRI) has been problematic since its introduction as a clinical imaging modality. While sensitivity to particle motion or blood flow can be used to provide useful image contrast, bulk motion presents a considerable problem in the majority of clinical applications. It is one of the most frequent sources of artifacts. Over 30 years of research have produced numerous methods to mitigate or correct for motion artifacts, but no single method can be applied in all imaging situations. Instead, a "toolbox" of methods exists, where each tool is suitable for some tasks, but not for others. This article reviews the origins of motion artifacts and presents current mitigation and correction methods. In some imaging situations, the currently available motion correction tools are highly effective; in other cases, appropriate tools still need to be developed. It seems likely that this multifaceted approach will be what eventually solves the motion sensitivity problem in MRI, rather than a single solution that is effective in all situations. This review places a strong emphasis on explaining the physics behind the occurrence of such artifacts, with the aim of aiding artifact detection and mitigation in particular clinical situations.

  2. Neural networks improve brain cancer detection with Raman spectroscopy in the presence of light artifacts

    Science.gov (United States)

    Jermyn, Michael; Desroches, Joannie; Mercier, Jeanne; St-Arnaud, Karl; Guiot, Marie-Christine; Petrecca, Kevin; Leblond, Frederic

    2016-03-01

    It is often difficult to identify cancer tissue during brain cancer (glioma) surgery. Gliomas invade into areas of normal brain, and this cancer invasion is frequently not detected using standard preoperative magnetic resonance imaging (MRI). This results in enduring invasive cancer following surgery and leads to recurrence. A hand-held Raman spectroscopy is able to rapidly detect cancer invasion in patients with grade 2-4 gliomas. However, ambient light sources can produce spectral artifacts which inhibit the ability to distinguish between cancer and normal tissue using the spectral information available. To address this issue, we have demonstrated that artificial neural networks (ANN) can accurately classify invasive cancer versus normal brain tissue, even when including measurements with significant spectral artifacts from external light sources. The non-parametric and adaptive model used by ANN makes it suitable for detecting complex non-linear spectral characteristics associated with different tissues and the confounding presence of light artifacts. The use of ANN for brain cancer detection with Raman spectroscopy, in the presence of light artifacts, improves the robustness and clinical translation potential for intraoperative use. Integration with the neurosurgical workflow is facilitated by accounting for the effect of light artifacts which may occur, due to operating room lights, neuronavigation systems, windows, or other light sources. The ability to rapidly detect invasive brain cancer under these conditions may reduce residual cancer remaining after surgery, and thereby improve patient survival.

  3. Automatic Identification of Motion Artifacts in EHG Recording for Robust Analysis of Uterine Contractions

    Directory of Open Access Journals (Sweden)

    Yiyao Ye-Lin

    2014-01-01

    Full Text Available Electrohysterography (EHG is a noninvasive technique for monitoring uterine electrical activity. However, the presence of artifacts in the EHG signal may give rise to erroneous interpretations and make it difficult to extract useful information from these recordings. The aim of this work was to develop an automatic system of segmenting EHG recordings that distinguishes between uterine contractions and artifacts. Firstly, the segmentation is performed using an algorithm that generates the TOCO-like signal derived from the EHG and detects windows with significant changes in amplitude. After that, these segments are classified in two groups: artifacted and nonartifacted signals. To develop a classifier, a total of eleven spectral, temporal, and nonlinear features were calculated from EHG signal windows from 12 women in the first stage of labor that had previously been classified by experts. The combination of characteristics that led to the highest degree of accuracy in detecting artifacts was then determined. The results showed that it is possible to obtain automatic detection of motion artifacts in segmented EHG recordings with a precision of 92.2% using only seven features. The proposed algorithm and classifier together compose a useful tool for analyzing EHG signals and would help to promote clinical applications of this technique.

  4. The Smoothing Artifact of Spatially Constrained Canonical Correlation Analysis in Functional MRI

    Directory of Open Access Journals (Sweden)

    Dietmar Cordes

    2012-01-01

    Full Text Available A wide range of studies show the capacity of multivariate statistical methods for fMRI to improve mapping of brain activations in a noisy environment. An advanced method uses local canonical correlation analysis (CCA to encompass a group of neighboring voxels instead of looking at the single voxel time course. The value of a suitable test statistic is used as a measure of activation. It is customary to assign the value to the center voxel; however, this is a choice of convenience and without constraints introduces artifacts, especially in regions of strong localized activation. To compensate for these deficiencies, different spatial constraints in CCA have been introduced to enforce dominance of the center voxel. However, even if the dominance condition for the center voxel is satisfied, constrained CCA can still lead to a smoothing artifact, often called the “bleeding artifact of CCA”, in fMRI activation patterns. In this paper a new method is introduced to measure and correct for the smoothing artifact for constrained CCA methods. It is shown that constrained CCA methods corrected for the smoothing artifact lead to more plausible activation patterns in fMRI as shown using data from a motor task and a memory task.

  5. Artifact removal algorithms for stroke detection using a multistatic MIST beamforming algorithm.

    Science.gov (United States)

    Ricci, E; Di Domenico, S; Cianca, E; Rossi, T

    2015-01-01

    Microwave imaging (MWI) has been recently proved as a promising imaging modality for low-complexity, low-cost and fast brain imaging tools, which could play a fundamental role to efficiently manage emergencies related to stroke and hemorrhages. This paper focuses on the UWB radar imaging approach and in particular on the processing algorithms of the backscattered signals. Assuming the use of the multistatic version of the MIST (Microwave Imaging Space-Time) beamforming algorithm, developed by Hagness et al. for the early detection of breast cancer, the paper proposes and compares two artifact removal algorithms. Artifacts removal is an essential step of any UWB radar imaging system and currently considered artifact removal algorithms have been shown not to be effective in the specific scenario of brain imaging. First of all, the paper proposes modifications of a known artifact removal algorithm. These modifications are shown to be effective to achieve good localization accuracy and lower false positives. However, the main contribution is the proposal of an artifact removal algorithm based on statistical methods, which allows to achieve even better performance but with much lower computational complexity.

  6. An Approach for Multi-Artifact Testing Through an Ontological Perspective for Behavior-Driven Development

    Directory of Open Access Journals (Sweden)

    Thiago Rocha Silva

    2016-07-01

    Full Text Available In a user-centered development process, artifacts evolve in iterative cycles until they meet users’ requirements and then become the final product. Every cycle gives the opportunity to revise the design and to introduce new requirements which might affect the specification of artifacts that have been set in former development phases. Testing the consistency of multiple artifacts used to develop interactive systems every time that new requirements are introduced is a cumbersome activity, especially if it is done manually. This paper proposes an approach based on Behavior-Driven Development (BDD to support the automated assessment of artifacts along the development process of interactive systems. The paper uses an ontology for specifying tests that can run over multiple artifacts sharing similar concepts. A case study testing Task Models, Prototypes, and Final User Interfaces is presented to demonstrate the feasibility of this approach from the early phases of the design process, providing a continuous quality assurance of requirements, and helping clients and development teams to identify potential problems and inconsistencies before commitments with software implementation are made.

  7. Artifacts and collaborative work in healthcare: methodological, theoretical, and technological implications of the tangible.

    Science.gov (United States)

    Xiao, Yan

    2005-02-01

    Although modeled as knowledge work with emphasis on data flow and decision making, healthcare is delivered in the context of a highly structured physical environment, with much effort and emphasis placed on physical and spatial arrangement and re-arrangement of workers, patients, and materials. The tangible aspects of highly collaborative healthcare work have profound implications for research and development of information and communication technology (ICT) despite the tendency to model work as flow of abstract data items. This article reviews field studies in healthcare and other domains on the role of artifacts in collaborative work and draws implications in three areas: methodological, theoretical, and technological. In regard to methodologies, assessment of new ICT and development of user requirements should take into account how artifacts are used and exploited to facilitate collaborative work. In regard to theories, the framework of distributed cognition provides a starting point for modeling the contribution and exploitation of physical artifacts in supporting collaborative work. In regard to technology, design and deployment of new technology should support the functions provided by physical artifacts replaced or disrupted by new technology, and profitable ways for new technology to support collaborative work by embedding ICT into existing infrastructure of physical artifacts.

  8. Accounting for microsaccadic artifacts in the EEG using independent component analysis and beamforming.

    Science.gov (United States)

    Craddock, Matt; Martinovic, Jasna; Müller, Matthias M

    2016-04-01

    Neuronal activity in the gamma-band range was long considered a marker of object representation. However, scalp-recorded EEG activity in this range is contaminated by a miniature saccade-related muscle artifact. Independent component analysis (ICA) has been proposed as a method of removal of such artifacts. Alternatively, beamforming, a source analysis method in which potential sources of activity across the whole brain are scanned independently through the use of adaptive spatial filters, offers a promising method of accounting for the artifact without relying on its explicit removal. We present here the application of ICA-based correction to a previously published dataset. Then, using beamforming, we examine the effect of ICA correction on the scalp-recorded EEG signal and the extent to which genuine activity is recoverable before and after ICA correction. We find that beamforming attributes much of the scalp-recorded gamma-band signal before correction to deep frontal sources, likely the eye muscles, which generate the artifact related to each miniature saccade. Beamforming confirms that what is removed by ICA is predominantly this artifactual signal, and that what remains after correction plausibly originates in the visual cortex. Thus, beamforming allows researchers to confirm whether their removal procedures successfully removed the artifact. Our results demonstrate that ICA-based correction brings about general improvements in signal-to-noise ratio suggesting it should be used along with, rather than be replaced by, beamforming.

  9. Aliasing of 60-Hz Artifact as a Result of Compressed Time Base.

    Science.gov (United States)

    Bolen, Robert D; Edwards, Jonathan C; Halford, Jonathan J

    2017-09-01

    Digital EEG has brought about greater flexibility in data interpretation but has also resulted in new and unique artifacts. As digital EEG has evolved, an increase in intensive care unit monitoring has occurred, bringing more sources of artifact to light. Aliasing as a result of a combination of compressed time base and display monitor resolution can result in appearance of spurious waveforms that can potentially skew interpretation. A portion of a digital EEG from an intensive care unit patient acquired at a sample rate of 1,024 Hz was reviewed at a time base of 15 mm/second on a monitor with a resolution of 1,920 × 1,080. At a time base of 15 mm/second, a 60-Hz artifact resulted in the appearance of a 4-Hz delta artifact that resolved when the time base was changed to a more standard 30 mm/second. A software malfunction of the digital antialiasing filter for display resulted in the appearance of a novel 4-Hz artifact.

  10. A method for estimating and removing streaking artifacts in quantitative susceptibility mapping.

    Science.gov (United States)

    Li, Wei; Wang, Nian; Yu, Fang; Han, Hui; Cao, Wei; Romero, Rebecca; Tantiwongkosi, Bundhit; Duong, Timothy Q; Liu, Chunlei

    2015-03-01

    Quantitative susceptibility mapping (QSM) is a novel MRI method for quantifying tissue magnetic property. In the brain, it reflects the molecular composition and microstructure of the local tissue. However, susceptibility maps reconstructed from single-orientation data still suffer from streaking artifacts which obscure structural details and small lesions. We propose and have developed a general method for estimating streaking artifacts and subtracting them from susceptibility maps. Specifically, this method uses a sparse linear equation and least-squares (LSQR)-algorithm-based method to derive an initial estimation of magnetic susceptibility, a fast quantitative susceptibility mapping method to estimate the susceptibility boundaries, and an iterative approach to estimate the susceptibility artifact from ill-conditioned k-space regions only. With a fixed set of parameters for the initial susceptibility estimation and subsequent streaking artifact estimation and removal, the method provides an unbiased estimate of tissue susceptibility with negligible streaking artifacts, as compared to multi-orientation QSM reconstruction. This method allows for improved delineation of white matter lesions in patients with multiple sclerosis and small structures of the human brain with excellent anatomical details. The proposed methodology can be extended to other existing QSM algorithms.

  11. Home-Explorer: Ontology-Based Physical Artifact Search and Hidden Object Detection System

    Directory of Open Access Journals (Sweden)

    Bin Guo

    2008-01-01

    Full Text Available A new system named Home-Explorer that searches and finds physical artifacts in a smart indoor environment is proposed. The view on which it is based is artifact-centered and uses sensors attached to the everyday artifacts (called smart objects in the real world. This paper makes two main contributions: First, it addresses, the robustness of the embedded sensors, which is seldom discussed in previous smart artifact research. Because sensors may sometimes be broken or fail to work under certain conditions, smart objects become hidden ones. However, current systems provide no mechanism to detect and manage objects when this problem occurs. Second, there is no common context infrastructure for building smart artifact systems, which makes it difficult for separately developed applications to interact with each other and uneasy for them to share and reuse knowledge. Unlike previous systems, Home-Explorer builds on an ontology-based knowledge infrastructure named Sixth-Sense, which makes it easy for the system to interact with other applications or agents also based on this ontology. The hidden object problem is also reflected in our ontology, which enables Home-Explorer to deal with both smart objects and hidden objects. A set of rules for deducing an object's status or location information and for locating hidden objects are described and evaluated.

  12. Pedogenesis, geochemical forms of heavy metals, and artifact weathering in an urban soil chronosequence, Detroit, Michigan

    Energy Technology Data Exchange (ETDEWEB)

    Howard, Jeffrey L., E-mail: jhoward@wayne.edu [Department of Geology, Wayne State University, Detroit, MI 48202 (United States); Olszewska, Dorota [Department of Geology, Wayne State University, Detroit, MI 48202 (United States)

    2011-03-15

    An urban soil chronosequence in downtown Detroit, MI was studied to determine the effects of time on pedogenesis and heavy metal sequestration. The soils developed in fill derived from mixed sandy and clayey diamicton parent materials on a level late Pleistocene lakebed plain under grass vegetation in a humid-temperate (mesic) climate. The chronosequence is comprised of soils in vacant lots (12 and 44 years old) and parks (96 and 120 years old), all located within 100 m of a roadway. An A-horizon 16 cm thick with 2% organic matter has developed after only 12 years of pedogenesis. The 12 year-old soil shows accelerated weathering of iron (e.g. nails) and cement artifacts attributed to corrosion by excess soluble salts of uncertain origin. Carbonate and Fe-oxide are immobilizing agents for heavy metals, hence it is recommended that drywall, plaster, cement and iron artifacts be left in soils at brownfield sites for their ameliorating effects. - Research highlights: > An A horizon has developed in these urban soils after only 12 years of pedogenesis. > Iron and cement artifacts have undergone accelerated weathering due to deicing salts. > One soil is contaminated by lead derived from weathered paint. > Artifact weathering can have ameliorating effects on urban soils contaminated by heavy metals. - Weathering of artifacts can have ameliorating effects on heavy metal-polluted soils at brownfield sites.

  13. Dual Adaptive Filtering by Optimal Projection Applied to Filter Muscle Artifacts on EEG and Comparative Study

    Directory of Open Access Journals (Sweden)

    Samuel Boudet

    2014-01-01

    Full Text Available Muscle artifacts constitute one of the major problems in electroencephalogram (EEG examinations, particularly for the diagnosis of epilepsy, where pathological rhythms occur within the same frequency bands as those of artifacts. This paper proposes to use the method dual adaptive filtering by optimal projection (DAFOP to automatically remove artifacts while preserving true cerebral signals. DAFOP is a two-step method. The first step consists in applying the common spatial pattern (CSP method to two frequency windows to identify the slowest components which will be considered as cerebral sources. The two frequency windows are defined by optimizing convolutional filters. The second step consists in using a regression method to reconstruct the signal independently within various frequency windows. This method was evaluated by two neurologists on a selection of 114 pages with muscle artifacts, from 20 clinical recordings of awake and sleeping adults, subject to pathological signals and epileptic seizures. A blind comparison was then conducted with the canonical correlation analysis (CCA method and conventional low-pass filtering at 30 Hz. The filtering rate was 84.3% for muscle artifacts with a 6.4% reduction of cerebral signals even for the fastest waves. DAFOP was found to be significantly more efficient than CCA and 30 Hz filters. The DAFOP method is fast and automatic and can be easily used in clinical EEG recordings.

  14. The morphology of fecal and regurgitation artifacts deposited by the blow fly Lucilia cuprina fed a diet of human blood.

    Science.gov (United States)

    Durdle, Annalisa; van Oorschot, Roland A H; Mitchell, R John

    2013-07-01

    Fly feces and regurgitation deposits may be mistaken for bloodstain patterns at a crime scene, potentially compromising event reconstruction and/or misdirecting police resources. In some instances, these artifacts contain sufficient human biological material to generate a full DNA profile, sometimes 2 years after deposition. Clearly, it is important that investigators can make the distinction between artifacts and bloodstains. This study examined 6645 artifacts deposited on a smooth, nonporous surface after Lucilia cuprina were fed human blood. Artifacts were also compared with bloodstains on a variety of other surfaces. Both similarities and differences were found between artifacts and bloodstains, highlighting the need for an identification system to assist personnel with little training in bloodstain pattern analysis. The morphology of the artifacts has been described so that these deposits may be more clearly distinguished from bloodstains, targeted by crime scene personnel as potential sources of human DNA, and/or identified as potential evidence contaminants. Flowcharts have been devised to facilitate the analysis.

  15. CT Image Artifacts with Corresponding Elimination Methods%CT图像伪影及其解决方案

    Institute of Scientific and Technical Information of China (English)

    赵传军; 王烈伟

    2014-01-01

    本文列举了常见的几种CT图像伪影,分析了其产生的原因及解决方案,旨在为临床科室提供避免伪影以得到高质量CT图像的有效方法。%This paper introduces several kinds of CT image artifacts and analyzes the causes of these artifacts. Then this paper gives corresponding elimination methods of these artifacts in order to provide effective methods for clinical departments to avoid artifacts and then get CT images with high quality.

  16. Artifact reduction in multichannel pervasive EEG using hybrid WPT-ICA and WPT-EMD signal decomposition techniques

    CERN Document Server

    Bono, Valentina; Das, Saptarshi; Maharatna, Koushik

    2014-01-01

    In order to reduce the muscle artifacts in multi-channel pervasive Electroencephalogram (EEG) signals, we here propose and compare two hybrid algorithms by combining the concept of wavelet packet transform (WPT), empirical mode decomposition (EMD) and Independent Component Analysis (ICA). The signal cleaning performances of WPT-EMD and WPT-ICA algorithms have been compared using a signal-to-noise ratio (SNR)-like criterion for artifacts. The algorithms have been tested on multiple trials of four different artifact cases viz. eye-blinking and muscle artifacts including left and right hand movement and head-shaking.

  17. Image quality analysis to reduce dental artifacts in head and neck imaging with dual-source computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Ketelsen, D.; Werner, M.K.; Thomas, C.; Tsiflikas, I.; Reimann, A.; Claussen, C.D.; Heuschmid, M. [Tuebingen Univ. (Germany). Abt. fuer Diagnostische und Interventionelle Radiologie; Koitschev, A. [Tuebingen Univ. (Germany). Abt. fuer Hals-Nasen-Ohrenheilkunde

    2009-01-15

    Purpose: Important oropharyngeal structures can be superimposed by metallic artifacts due to dental implants. The aim of this study was to compare the image quality of multiplanar reconstructions and an angulated spiral in dual-source computed tomography (DSCT) of the neck. Materials and Methods: Sixty-two patients were included for neck imaging with DSCT. MPRs from an axial dataset and an additional short spiral parallel to the mouth floor were acquired. Leading anatomical structures were then evaluated with respect to the extent to which they were affected by dental artifacts using a visual scale, ranging from 1 (least artifacts) to 4 (most artifacts). Results: In MPR, 87.1 % of anatomical structures had significant artifacts (3.12 {+-} 0.86), while in angulated slices leading anatomical structures of the oropharynx showed negligible artifacts (1.28 {+-} 0.46). The diagnostic growth due to primarily angulated slices concerning artifact severity was significant (p < 0.01). Conclusion: MPRs are not capable of reducing dental artifacts sufficiently. In patients with dental artifacts overlying the anatomical structures of the oropharynx, an additional short angulated spiral parallel to the floor of the mouth is recommended and should be applied for daily routine. As a result of the static gantry design of DSCT, the use of a flexible head holder is essential. (orig.)

  18. Weighted phase lag index stability as an artifact resistant measure to detect cognitive EEG activity during locomotion

    National Research Council Canada - National Science Library

    Lau, Troy M; Gwin, Joseph T; McDowell, Kaleb G; Ferris, Daniel P

    2012-01-01

    High-density electroencephalography (EEG) with active electrodes allows for monitoring of electrocortical dynamics during human walking but movement artifacts have the potential to dominate the signal...

  19. Novel technique for addressing streak artifact in gated dual-source MDCT angiography utilizing ECG-editing

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, Laura T.; Boll, Daniel T. [Duke University Medical Center, Department of Radiology, Box 3808, Durham, NC (United States)

    2008-11-15

    Streak artifact is an important source of image degradation in computed tomographic imaging. In coronary MDCT angiography, streak artifact from pacemaker leads in the SVC can render segments of the right coronary artery uninterpretable. With current technology in clinical practice, there is no effective way to eliminate streak artifact in coronary MDCT angiography entirely. We propose a technique to minimize the impact of streak artifact in retrospectively gated coronary MDCT angiography by utilizing small shifts in the reconstruction window. In our experience, previously degraded portions of the coronary vasculature were able to be well evaluated using this technique. (orig.)

  20. Multidetector CT imaging of mechanical prosthetic heart valves: quantification of artifacts with a pulsatile in-vitro model

    Energy Technology Data Exchange (ETDEWEB)

    Symersky, Petr [Onze Lieve Vrouwe Gasthuis, Department of Cardiothoracic Surgery, Oosterpark 9, P.O box 95500, Amsterdam (Netherlands); Academic Medical Center, Department of Cardiothoracic Surgery, Amsterdam (Netherlands); Budde, Ricardo P.J. [University Medical Center, Department of Radiology, Utrecht (Netherlands); Westers, Paul [Julius Center for Health Sciences and Primary Care, Department of Biostatistics, Utrecht (Netherlands); Mol, Bas A.J.M. de [Academic Medical Center, Department of Cardiothoracic Surgery, Amsterdam (Netherlands); University of Technology Eindhoven, Department of Biomedical Engineering, Eindhoven (Netherlands); Prokop, Mathias [Radboud University Nijmegen Medical Center, Department of Radiology, Nijmegen (Netherlands)

    2011-10-15

    Multidetector computed tomography (MDCT) can detect the cause of prosthetic heart valve (PHV) dysfunction but is hampered by valve-induced artifacts. We quantified artifacts of four PHV using a pulsatile in-vitro model and assessed the relation to leaflet motion and valve design. A Medtronic Hall tilting disc (MH), and Carbomedics (CM), St Jude (SJM), and ON-X bileaflet valves underwent CT in an in-vitro model using retrospective gating with a 64 detector CT system in stationary and pulsatile conditions. Artifacts and radiopaque component volumes were quantified with thresholds based on surrounding structures and valvular components. Hypodense artifacts volumes (mm{sup 3}) were 1,029 {+-} 147, 535 {+-} 53, 371 {+-} 16, and 366 {+-} 18 for the SJM, MH, CM and ON-X valves (p < 0.001 except for the latter two valves p = 0.43). Hyperdense artifact volumes were 3,546 {+-} 141, 2,387 {+-} 103, 2,003 {+-} 102, and 3,033 {+-} 31 for the SJM, MH, CM and ON-X valve, respectively (all differences p < 0.001). Leaflet motion affected hypodense (F = 41.5, p < 0.001) and hyperdense artifacts (F = 53.7, p < 0.001). Closed and moving leaflets were associated with the least and the most artifacts respectively (p < 0.001, both artifact types). Both valve design and leaflet motion affect PHV-induced artifacts. Best imaging results may be expected for the CM valve during phases in which the leaflets are closed. (orig.)

  1. Reducing of gradient induced artifacts on the ECG signal during MRI examinations using Wilcoxon filter

    Directory of Open Access Journals (Sweden)

    Schmidt Marcus

    2016-09-01

    Full Text Available The electrocardiogramm (ECG is the state-of-the-art signal for gating in cardiovascular magnetic resonance imaging and patient monitoring. Using the ECG for gating and monitoring during the magnetic resonance imaging examination is a high challenging task due to the superimposition of the magnetohydrodynamic effect, radio-frequency (RF pulses and fast switching gradient magnetic fields. The gradient induced artifacts hamper the correct QRS detection which is needed for correct gating and heart rate calculation and ECG displaying for patient monitoring. To suppress the gradient artifacts from the ECG signal acquired during MRI, a technique based on the Wilcoxon filter was developed. It was evaluated using ECG signals of 14 different subjects acquired in a 3 T MRI scanner. It could be shown reliable results for reducing gradient induced artifacts in the ECG signal in real-time.

  2. An adaptive fuzzy filter for coding artifacts removal in video and image

    Institute of Scientific and Technical Information of China (English)

    WU Jing; YE Xiu-qing; GU Wei-kang

    2007-01-01

    This paper proposes a new adaptive post-filtering algorithm to remove coding artifacts in block-based video coder. The proposed method concentrates on blocking and ringing artifacts removal. For de-blocking, the blocking strength is identified to determine the filtering range, and the maximum quantization parameter of the image is used to adapt the 1D fuzzy filter. For de-ringing, besides the edge detection, a complementary ringing detection method is proposed to locate the neglected ringing blocks, and the gradient threshold is adopted to adjust the parameter of 2D fuzzy filter. Experiments are performed on the MPEG-4 sequences. Compared with other methods, the proposed one achieves better detail preservation and artifacts removal performance with lower computational cost.

  3. On artifacts in limited data spherical Radon transform: curved observation surface

    DEFF Research Database (Denmark)

    Barannyk, Lyudmyla L.; Frikel, Jürgen; Nguyen, Linh V.

    2015-01-01

    We study the limited data problem of the spherical Radon transform in two and three-dimensional spaces with general acquisition surfaces. In such situations, it is known that the application of filtered-backprojection reconstruction formulas might generate added artifacts and degrade the quality...... of reconstructions. In this article, we explicitly analyze a family of such inversion formulas, depending on a smoothing function that vanishes to order k on the boundary of the acquisition surfaces. We show that the artifacts are k orders smoother than their generating singularity. Moreover, in two......-dimensional space, if the generating singularity is conormal satisfying a generic condition then the artifacts are even orders smoother than the generating singularity. Our analysis for three-dimensional space contains an important idea of lifting up space. We also explore the theoretical findings in a series...

  4. Storing and managing information artifacts collected by information analysts using a computing device

    Science.gov (United States)

    Pike, William A; Riensche, Roderick M; Best, Daniel M; Roberts, Ian E; Whyatt, Marie V; Hart, Michelle L; Carr, Norman J; Thomas, James J

    2012-09-18

    Systems and computer-implemented processes for storage and management of information artifacts collected by information analysts using a computing device. The processes and systems can capture a sequence of interactive operation elements that are performed by the information analyst, who is collecting an information artifact from at least one of the plurality of software applications. The information artifact can then be stored together with the interactive operation elements as a snippet on a memory device, which is operably connected to the processor. The snippet comprises a view from an analysis application, data contained in the view, and the sequence of interactive operation elements stored as a provenance representation comprising operation element class, timestamp, and data object attributes for each interactive operation element in the sequence.

  5. A Practical Ontology for the Large-Scale Modeling of Scholarly Artifacts and their Usage

    CERN Document Server

    Rodriguez, Marko A; Van de Sompel, Herbert

    2007-01-01

    The large-scale analysis of scholarly artifact usage is constrained primarily by current practices in usage data archiving, privacy issues concerned with the dissemination of usage data, and the lack of a practical ontology for modeling the usage domain. As a remedy to the third constraint, this article presents a scholarly ontology that was engineered to represent those classes for which large-scale bibliographic and usage data exists, supports usage research, and whose instantiation is scalable to the order of 50 million articles along with their associated artifacts (e.g. authors and journals) and an accompanying 1 billion usage events. The real world instantiation of the presented abstract ontology is a semantic network model of the scholarly community which lends the scholarly process to statistical analysis and computational support. We present the ontology, discuss its instantiation, and provide some example inference rules for calculating various scholarly artifact metrics.

  6. Dispersing artifacts in FT-STS: a comparison of set point effects across acquisition modes

    Science.gov (United States)

    Macdonald, A. J.; Tremblay-Johnston, Y.-S.; Grothe, S.; Chi, S.; Dosanjh, P.; Johnston, S.; Burke, S. A.

    2016-10-01

    Fourier-transform scanning tunnelling spectroscopy (FT-STS), or quasiparticle interference, has become an influential tool for the study of a wide range of important materials in condensed matter physics. However, FT-STS in complex materials is often challenging to interpret, requiring significant theoretical input in many cases, making it crucial to understand potential artifacts of the measurement. Here, we compare the most common modes of acquiring FT-STS data and show through both experiment and simulations that artifact features can arise that depend on how the tip height is stabilized throughout the course of the measurement. The most dramatic effect occurs when a series of dI/dV maps at different energies are acquired with simultaneous constant current feedback; here a feature that disperses in energy appears that is not observed in other measurement modes. Such artifact features are similar to those arising from real physical processes in the sample and are susceptible to misinterpretation.

  7. Substance and artifact in the higher-order factors of the Big Five.

    Science.gov (United States)

    McCrae, Robert R; Yamagata, Shinji; Jang, Kerry L; Riemann, Rainer; Ando, Juko; Ono, Yutaka; Angleitner, Alois; Spinath, Frank M

    2008-08-01

    J. M. Digman (1997) proposed that the Big Five personality traits showed a higher-order structure with 2 factors he labeled alpha and beta. These factors have been alternatively interpreted as heritable components of personality or as artifacts of evaluative bias. Using structural equation modeling, the authors reanalyzed data from a cross-national twin study and from American cross-observer studies and analyzed new multimethod data from a German twin study. In all analyses, artifact models outperformed substance models by root-mean-square error of approximation criteria, but models combining both artifact and substance were slightly better. These findings suggest that the search for the biological basis of personality traits may be more profitably focused on the 5 factors themselves and their specific facets, especially in monomethod studies. (c) 2008 APA, all rights reserved

  8. Analyzing Pictorial Artifacts from Psychotherapy and Art Therapy Oelated to overcoming Stress and Trauma

    DEFF Research Database (Denmark)

    Gerge, Anna; Pedersen, Inge Nygaard

    2017-01-01

    Abstract This process based article tries to zoom into the need for assessment tools from a wider perspective to come to a preliminary understanding of what to analyze in relation to overcome traumatization and dissociation. The article wants to discuss and build understanding on what we ought...... to look for in pictorial artifacts related overcome traumatization and dissociation. After an introduction to psychotraumatology and it’s adaptions to creative arts therapy and art therapy, a literature review on assessment tools in art therapy, which can be applicable for measuring overcome...... traumatization, will be addressed. The need of a multi-dimensional tool for analysis of pictorial artifacts done in therapy is asked for and the needed components are briefly sketched. Finally the value of pictorial artifacts, made by clients in psycho-social interventions, as valid “windows” of implicit change...

  9. Forming Mechanism and Correction of CT Image Artifacts Caused by the Errors of Three System Parameters

    Directory of Open Access Journals (Sweden)

    Ming Chen

    2013-01-01

    Full Text Available We know that three system parameters, a center of X-ray source, an isocenter, and a center of linear detectors, are very difficult to be calibrated in industrial CT system. So there are often the offset of an isocenter and the deflection of linear detectors. When still using the FBP (filtered backprojection algorithm under this condition, CT image artifacts will happen and then can seriously affect test results. In this paper, we give the appearances and forming mechanism of these artifacts and propose the reconstruction algorithm including a deflection angle of linear detectors. The numerical experiments with simulated data have validated that our propose algorithm can correct CT images artifacts without data rebinning.

  10. Detection and removal of ocular artifacts from EEG signals for an automated REM sleep analysis.

    Science.gov (United States)

    Betta, Monica; Gemignani, Angelo; Landi, Alberto; Laurino, Marco; Piaggi, Paolo; Menicucci, Danilo

    2013-01-01

    Rapid eye movements (REMs) are a prominent feature of REM sleep, and their distribution and time density over the night represent important physiological and clinical parameters. At the same time, REMs produce substantial distortions on the electroencephalographic (EEG) signals, which strongly affect the significance of normal REM sleep quantitative study. In this work a new procedure for a complete and automated analysis of REM sleep is proposed, which includes both a REMs detection algorithm and an ocular artifact removal system. The two steps, based respectively on Wavelet Transform and adaptive filtering, are fully integrated and their performance is evaluated using REM simulated signals. Thanks to the integration with the detection algorithm, the proposed artifact removal system shows an enhanced accuracy in the recovering of the true EEG signal, compared to a system based on the adaptive filtering only. Finally the artifact removal system is applied to physiological data and an estimation of the actual distortion induced by REMs on EEG signals is supplied.

  11. Photoacoustic-guided focused ultrasound (PAFUSion for identifying reflection artifacts in photoacoustic imaging

    Directory of Open Access Journals (Sweden)

    Mithun Kuniyil Ajith Singh

    2015-12-01

    Full Text Available Influence of acoustic inhomogeneities and resulting reflection artifacts is an important problem in reflection-mode photoacoustic imaging. Absorption of light by skin and superficial optical absorbers will generate photoacoustic transients, which traverse into the tissue and get reflected from structures having different acoustic impedance. These reflected photoacoustic signals, when reconstructed, may appear in the region of interest, which causes difficulties in image interpretation. We propose a novel method to identify and potentially eliminate reflection artifacts in photoacoustic images using photoacoustic-guided focused ultrasound [PAFUSion]. Our method uses focused ultrasound pulses to mimic the wave field produced by photoacoustic sources and thus provides a way to identify reflection artifacts in clinical combined photoacoustic and pulse-echo ultrasound. Simulation and phantom results are presented to demonstrate the validity and impact of this method. Results show that PAFUSion can identify reflections in photoacoustic images and thus envisages potential for improving photoacoustic imaging of acoustically inhomogeneous tissue.

  12. Motion artifact reduction using hybrid Fourier transform with phase-shifting methods

    Science.gov (United States)

    Li, Beiwen; Liu, Ziping; Zhang, Song

    2016-08-01

    We propose to combine the Fourier transform profilometry (FTP) and phase-shifting profilometry (PSP) to reduce motion induced artifacts. The proposed method can be divided into three steps: Step 1 is to obtain a temporarily unwrapped absolute phase map of the entire scene using the FTP method, albeit the absolute phase map has motion introduced artifacts; Step 2 is to generate continuous relative phase maps without motion artifacts for each isolated object by spatially unwrapping each isolated phase map retrieved from the FTP method; and Step 3 is to determine the absolute phase map for each isolate region by referring to the temporally unwrapped phase using PSP method. Experimental results demonstrated success of the proposed method for measuring rapidly moving multiple isolated objects.

  13. Removing artifacts and background activity in multichannel electroencephalograms by enhancing common activity.

    Science.gov (United States)

    De Clercq, Wim; Van Paesschen, Wim; Vanrumste, Bart; Papy, J-M; Vergult, Anneleen; Van Huffel, Sabine

    2005-01-01

    Removing artifacts and background EEG from multichannel interictal and ictal EEG has become a major research topic in EEG signal processing in recent years. We applied for this purpose a recently developed subspace-based method for modelling the common dynamics in multichannel signals. When the epileptiform activity is common in the majority of channels and the artifacts appear only in a few channels the proposed method can be used to remove the latter. The performance of the method was tested on simulated data for different noise levels. For high noise levels the method was still able to identify the common dynamics. In addition, the method was applied to a real life EEG recording. Also in this case the muscle artifacts were removed successfully. For both the synthetic data and the analyzed real life data the results were compared with the results obtained with principal component analysis (PCA). In both cases the proposed method performed better than PCA.

  14. Automated motion artifact removal for intravital microscopy, without a priori information

    Science.gov (United States)

    Lee, Sungon; Vinegoni, Claudio; Sebas, Matthew; Weissleder, Ralph

    2014-03-01

    Intravital fluorescence microscopy, through extended penetration depth and imaging resolution, provides the ability to image at cellular and subcellular resolution in live animals, presenting an opportunity for new insights into in vivo biology. Unfortunately, physiological induced motion components due to respiration and cardiac activity are major sources of image artifacts and impose severe limitations on the effective imaging resolution that can be ultimately achieved in vivo. Here we present a novel imaging methodology capable of automatically removing motion artifacts during intravital microscopy imaging of organs and orthotopic tumors. The method is universally applicable to different laser scanning modalities including confocal and multiphoton microscopy, and offers artifact free reconstructions independent of the physiological motion source and imaged organ. The methodology, which is based on raw data acquisition followed by image processing, is here demonstrated for both cardiac and respiratory motion compensation in mice heart, kidney, liver, pancreas and dorsal window chamber.

  15. Neutron measurements of stresses in a test artifact produced by laser-based additive manufacturing

    Science.gov (United States)

    Gnäupel-Herold, Thomas; Slotwinski, John; Moylan, Shawn

    2014-02-01

    A stainless steel test artifact produced by Direct Metal Laser Sintering and similar to a proposed standardized test artifact was examined using neutron diffraction. The artifact contained a number of structures with different aspect ratios pertaining to wall thickness, height above base plate, and side length. Through spatial resolutions of the order of one millimeter the volumetric distribution of stresses in several was measured. It was found that the stresses peak in the tensile region around 500 MPa near the top surface, with balancing compressive stresses in the interior. The presence of a support structure (a one millimeter high, thin walled, hence weaker, lattice structure deposited on the base plate, followed by a fully dense AM structure) has only minor effects on the stresses.

  16. Fullerenes in asphaltenes and other carbonaceous materials: natural constituents or laser artifacts.

    Science.gov (United States)

    Santos, Vanessa G; Fasciotti, Maíra; Pudenzi, Marcos A; Klitzke, Clécio F; Nascimento, Heliara L; Pereira, Rosana C L; Bastos, Wagner L; Eberlin, Marcos N

    2016-04-25

    The presence of fullerenes as natural constituents of carbonaceous materials or their formation as laser artifacts during laser desorption ionization (LDI) mass spectrometry (MS) analysis is reinvestigated and reviewed. The results using asphaltene samples with varying composition as well as standard polycyclic aromatic hydrocarbons (PAH) and fullerene samples as models have demonstrated that indeed Cn ring fullerenes are not natural constituents but they are formed as common and often as predominant artifacts upon laser radiation, and a series of incorrect assignments based on LDI-MS data of several carbonaceous materials seems unfortunately to have been made. When the present results are evaluated also in the light of the vast literature on LDI-MS of carbonaceous materials, the formation of fullerene artifacts seems particularly common for LDI-MS analysis of asphaltenes and other carbonaceous samples with considerably high levels of PAH and varies according to the type of laser used, and the intensity of the laser beam.

  17. Artifact removal for GLS map makers by means of post-processing.

    Science.gov (United States)

    Piazzo, Lorenzo; Ikhenaode, David; Natoli, Paolo; Pestalozzi, Michele; Piacentini, Francesco; Traficante, Alessio

    2012-08-01

    The quality of astrophysical images produced by means of the Generalised Least Square (GLS) approach may be degraded by the presence of artificial structures, obviously not present in the sky. This problem affects in different degrees all images produced by the instruments onboard the European Space Agency (ESA) Herschel satellite. In this paper we analyse these artifacts and introduce a method to remove them. The method is based on a post-processing of GLS image that estimates and removes the artifacts subtracting them from the original image. We find that the only drawback of this method is a slight increase of the background noise which, however, can be mitigated by detecting the artifacts and by performing the subtraction only where they are detected. The efficiency of the approach is demonstrated and quantified using simulated and real data.

  18. Was it designed to do that? Children's focus on intended function in their conceptualization of artifacts.

    Science.gov (United States)

    Asher, Yvonne M; Kemler Nelson, Deborah G

    2008-01-01

    Do young children who seek the conceptual kind of an artifact weigh the plausibility that a current function constitutes the function intended by the object designer? Three- and four-year-olds were encouraged to question adults about novel artifacts. After inquiring about what an object was, some children were shown a function that plausibly accounted for the structural features of the object; others were shown a possible, but implausible function. Children given implausible functions were less satisfied with these responses than those given plausible functions, as shown by their more persistent attempts to ask follow-up questions about function. Accordingly, preschoolers appear to take into account matters of intentional design when assigning artifacts to conceptual kinds.

  19. A PRACTICAL ONTOLOGY FOR THE LARGE-SCALE MODELING OF SCHOLARLY ARTIFACTS AND THEIR USAGE

    Energy Technology Data Exchange (ETDEWEB)

    RODRIGUEZ, MARKO A. [Los Alamos National Laboratory; BOLLEN, JOHAN [Los Alamos National Laboratory; VAN DE SOMPEL, HERBERT [Los Alamos National Laboratory

    2007-01-30

    The large-scale analysis of scholarly artifact usage is constrained primarily by current practices in usage data archiving, privacy issues concerned with the dissemination of usage data, and the lack of a practical ontology for modeling the usage domain. As a remedy to the third constraint, this article presents a scholarly ontology that was engineered to represent those classes for which large-scale bibliographic and usage data exists, supports usage research, and whose instantiation is scalable to the order of 50 million articles along with their associated artifacts (e.g. authors and journals) and an accompanying 1 billion usage events. The real world instantiation of the presented abstract ontology is a semantic network model of the scholarly community which lends the scholarly process to statistical analysis and computational support. They present the ontology, discuss its instantiation, and provide some example inference rules for calculating various scholarly artifact metrics.

  20. Development of neck filters for reducing artifact in cervical bone SPECT

    Energy Technology Data Exchange (ETDEWEB)

    Kikkawa, Nobutada; Kimura, Shigeo [Kyoto Minami Hospital (Japan)

    2001-01-01

    In cervical bone scintillation SPECT studies using triple energy window (TEW) and ordered subject-expection maximization (OS-EM) methods, we have observed an artifact that may interfere with evaluation of the image; higher accumulation in cervical vertebra compared with in the head and thoracic vertebra. As the neck is smaller in diameter than in the thorax and head, gamma ray absorption is lower. In addition, as the distance between the neck and the detector is greater, scattered gamma rays are increased, interfering with imaging and causing artifact. To overcome these problems, we have developed special absorbers (neck filter) to make the relative absorption level of the neck comparable to that of the head and thorax and have employed these cervical filters in bone scintillation SPECT studies in combination with TEW scatter correction and OS-EM method. Our results showed that artifacts were significantly reduced and satisfactory images were obtained. (author)

  1. Gibbs-Ringing Artifact Removal Based on Local Subvoxel-shifts

    CERN Document Server

    Kellner, Elias; Reisert, Marco

    2015-01-01

    Gibbs-ringing is a well known artifact which manifests itself as spurious oscillations in the vicinity of sharp image transients, e.g. at tissue boundaries. The origin can be seen in the truncation of k-space during MRI data-acquisition. Consequently, correction techniques like Gegenbauer reconstruction or extrapolation methods aim at recovering these missing data. Here, we present a simple and robust method which exploits a different view on the Gibbs-phenomena. The truncation in k-space can be interpreted as a convolution with a sinc-function in image space. Hence, the severity of the artifacts depends on how the sinc-function is sampled. We propose to re-interpolate the image based on local, subvoxel shifts to sample the ringing pattern at the zero-crossings of the oscillating sinc-function. With this, the artifact can effectively and robustly be removed with a minimal amount of smoothing.

  2. Factored Facade Acquisition using Symmetric Line Arrangements

    KAUST Repository

    Ceylan, Duygu

    2012-05-01

    We introduce a novel framework for image-based 3D reconstruction of urban buildings based on symmetry priors. Starting from image-level edges, we generate a sparse and approximate set of consistent 3D lines. These lines are then used to simultaneously detect symmetric line arrangements while refining the estimated 3D model. Operating both on 2D image data and intermediate 3D feature representations, we perform iterative feature consolidation and effective outlier pruning, thus eliminating reconstruction artifacts arising from ambiguous or wrong stereo matches. We exploit non-local coherence of symmetric elements to generate precise model reconstructions, even in the presence of a significant amount of outlier image-edges arising from reflections, shadows, outlier objects, etc. We evaluate our algorithm on several challenging test scenarios, both synthetic and real. Beyond reconstruction, the extracted symmetry patterns are useful towards interactive and intuitive model manipulations.

  3. Removal of ring artifacts in CT imaging through detection and correction of stripes in the sinogram

    Science.gov (United States)

    Abu Anas, Emran Mohammad; Lee, Soo Yeol; Kamrul Hasan, Md.

    2010-11-01

    Due to malfunctioning and mis-calibration of cells in digital x-ray detectors as well as impurities on the scintillator screens, stripe artifacts arise in the sinogram which in turn generate ring artifacts in the reconstructed x-ray computed tomography images. In this paper, a novel technique is proposed for the detection and removal of stripe artifacts in a sinogram with a view to suppress the ring artifacts from the tomographic images. To accurately detect the stripe creating pixels using a derivative-based algorithm, at first the sinogram is windowed to create a sub-sinogram by keeping the pixel of examination at the center position in the sub-sinogram. The other pixels in the sub-sinogram are selected from a polyphase component of the sinogram. A new mathematical index is proposed here to isolate the strong and weak ring-generating stripes from the good ones. For the correction of strong ring artifacts resulting from the defective detector elements and dusty scintillator crystals, 2D variable window moving average and weighted moving average filters are proposed in this work. On the other hand, a conventionally trusted constant bias correction scheme is adopted to correct the responses of the mis-calibrated detector elements. To evaluate and compare the performance of the proposed algorithm, real micro-CT images acquired from two flat panel detectors under different operating conditions are used. Experimental results show that the proposed method can remove ring artifacts more effectively without imparting noticeable distortion in the image as compared to a recently reported technique in the literature.

  4. Language and other artifacts: socio-cultural dynamics of niche construction.

    Science.gov (United States)

    Sinha, Chris

    2015-01-01

    Niche construction theory is a relatively new approach in evolutionary biology that seeks to integrate an ecological dimension into the Darwinian theory of evolution by natural selection. It is regarded by many evolutionary biologists as providing a significant revision of the Neo-Darwinian modern synthesis that unified Darwin's theory of natural and sexual selection with 20th century population genetics. Niche construction theory has been invoked as a processual mediator of social cognitive evolution and of the emergence and evolution of language. I argue that language itself can be considered as a biocultural niche and evolutionary artifact. I provide both a general analysis of the cognitive and semiotic status of artifacts, and a formal analysis of language as a social and semiotic institution, based upon a distinction between the fundamental semiotic relations of "counting as" and "standing for." I explore the consequences for theories of language and language learning of viewing language as a biocultural niche. I suggest that not only do niches mediate organism-organism interactions, but also that organisms mediate niche-niche interactions in ways that affect evolutionary processes, with the evolution of human infancy and childhood as a key example. I argue that language as a social and semiotic system is not only grounded in embodied engagements with the material and social-interactional world, but also grounds a sub-class of artifacts of particular significance in the cultural history of human cognition. Symbolic cognitive artifacts materially and semiotically mediate human cognition, and are not merely informational repositories, but co-agentively constitutive of culturally and historically emergent cognitive domains. I provide examples of the constitutive cognitive role of symbolic cognitive artifacts drawn from my research with my colleagues on cultural and linguistic conceptualizations of time, and their cultural variability. I conclude by reflecting on

  5. A Channel Rejection Method for Attenuating Motion-Related Artifacts in EEG Recordings during Walking.

    Science.gov (United States)

    Oliveira, Anderson S; Schlink, Bryan R; Hairston, W David; König, Peter; Ferris, Daniel P

    2017-01-01

    Recording scalp electroencephalography (EEG) during human motion can introduce motion artifacts. Repetitive head movements can generate artifact patterns across scalp EEG sensors. There are many methods for identifying and rejecting bad channels and independent components from EEG datasets, but there is a lack of methods dedicated to evaluate specific intra-channel amplitude patterns for identifying motion-related artifacts. In this study, we proposed a template correlation rejection (TCR) as a novel method for identifying and rejecting EEG channels and independent components carrying motion-related artifacts. We recorded EEG data from 10 subjects during treadmill walking. The template correlation rejection method consists of creating templates of amplitude patterns and determining the fraction of total epochs presenting relevant correlation to the template. For EEG channels, the template correlation rejection removed channels presenting the majority of epochs (>75%) correlated to the template, and presenting pronounced amplitude in comparison to all recorded channels. For independent components, the template correlation rejection removed components presenting the majority of epochs correlated to the template. Evaluation of scalp maps and power spectra confirmed low neural content for the rejected components. We found that channels identified for rejection contained ~60% higher delta power, and had spectral properties locked to the gait phases. After rejecting the identified channels and running independent component analysis on the EEG datasets, the proposed method identified 4.3 ± 1.8 independent components (out of 198 ± 12) with substantive motion-related artifacts. These results indicate that template correlation rejection is an effective method for rejecting EEG channels contaminated with motion-related artifact during human locomotion.

  6. A Channel Rejection Method for Attenuating Motion-Related Artifacts in EEG Recordings during Walking

    Directory of Open Access Journals (Sweden)

    Anderson S. Oliveira

    2017-04-01

    Full Text Available Recording scalp electroencephalography (EEG during human motion can introduce motion artifacts. Repetitive head movements can generate artifact patterns across scalp EEG sensors. There are many methods for identifying and rejecting bad channels and independent components from EEG datasets, but there is a lack of methods dedicated to evaluate specific intra-channel amplitude patterns for identifying motion-related artifacts. In this study, we proposed a template correlation rejection (TCR as a novel method for identifying and rejecting EEG channels and independent components carrying motion-related artifacts. We recorded EEG data from 10 subjects during treadmill walking. The template correlation rejection method consists of creating templates of amplitude patterns and determining the fraction of total epochs presenting relevant correlation to the template. For EEG channels, the template correlation rejection removed channels presenting the majority of epochs (>75% correlated to the template, and presenting pronounced amplitude in comparison to all recorded channels. For independent components, the template correlation rejection removed components presenting the majority of epochs correlated to the template. Evaluation of scalp maps and power spectra confirmed low neural content for the rejected components. We found that channels identified for rejection contained ~60% higher delta power, and had spectral properties locked to the gait phases. After rejecting the identified channels and running independent component analysis on the EEG datasets, the proposed method identified 4.3 ± 1.8 independent components (out of 198 ± 12 with substantive motion-related artifacts. These results indicate that template correlation rejection is an effective method for rejecting EEG channels contaminated with motion-related artifact during human locomotion.

  7. Language and other artifacts: socio-cultural dynamics of niche construction.

    Directory of Open Access Journals (Sweden)

    Chris eSinha

    2015-10-01

    Full Text Available Niche construction theory is a relatively new approach in evolutionary biology that seeks to integrate an ecological dimension into the Darwinian theory of evolution by natural selection. It is regarded by many evolutionary biologists as providing a significant revision of the Neo-Darwinian modern synthesis that unified Darwin’s theory of natural and sexual selection with 20th century population genetics. Niche construction theory has been invoked as a processual mediator of social cognitive evolution and of the emergence and evolution of language. I argue that language itself can be considered as a biocultural niche and evolutionary artifact. I provide both a general analysis of the cognitive and semiotic status of artifacts, and a formal analysis of language as a social and semiotic institution, based upon a distinction between the fundamental semiotic relations of counting as and standing for. I explore the consequences for theories of language and language learning of viewing language as a biocultural niche. I suggest that not only do niches mediate organism-organism interactions, but also that organisms mediate niche-niche interactions in ways that affect evolutionary processes, with the evolution of human infancy and childhood as a key example. I argue that language as a social and semiotic system is not only grounded in embodied engagements with the material and social-interactional world, but also grounds a sub-class of artifacts of particular significance in the cultural history of human cognition. Symbolic cognitive artifacts materially and semiotically mediate human cognition, and are not merely informational repositories, but co-agentively constitutive of culturally and historically emergent cognitive domains. I provide examples of the constitutive cognitive role of symbolic cognitive artifacts drawn from my research with my colleagues on cultural and linguistic conceptualizations of time, and their cultural variability. I conclude

  8. Digital tomosynthesis of the thorax - The influence of respiratory motion artifacts on lung nodule detection

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sung Mok; Chung, Myung Jin; Lee, Kyung Soo; Kang, Hee; Song, In-Young; Lee, Eun Joo; Hwang, Hye Sun [Dept. of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan Univ. School of Medicine, Seoul (Korea, Republic of)], e-mail: mj1.chung@samsung.com

    2013-07-15

    Background: Digital tomosynthesis considerably reduces problems created by overlapping anatomy compared with chest X-ray (CXR). However, digital tomosynthesis requires a longer scan time compared with CXR, and thus may be vulnerable to motion artifacts. Purpose: To compare the diagnostic performance of digital tomosynthesis in subjects with and without respiratory motion artifacts. Material and Methods: The institutional review board approved this retrospective study, and the requirement for written informed consent was waived. A total of 46 subjects with imaging containing respiratory motion artifacts were enrolled in this study, 18 of whom were positive and 28 of whom were negative for lung nodules on computed tomography (CT). The control group was comprised of 92 age-matched subjects with imaging devoid of motion artifacts. Of these, 36 were positive and 56 were negative for lung nodules on subsequent CT scan. The size criteria of nodules were 4-0 mm. Three chest radiologists independently evaluated the radiographs and digital tomosynthesis images for the presence of pulmonary nodules. Multireader multicase receiver-operating characteristic (ROC) analyses was used for statistical comparisons. Results: Within the control group, the areas under curve (AUC) for observer performances in detecting lung nodules on digital tomosynthesis was higher than that on CXR (P = 0.017). Within the study group, there were no significant differences in AUCs for observer performances (P = 0.576). Conclusion: When no motion artifacts are present, the detection performance of nodules (4-10 mm) on digital tomosynthesis is significantly better than that on CXR, whereas there is not a significant difference in cases with motion artifacts.

  9. The emergence of semantic categorization in early visual processing: ERP indices of animal vs. artifact recognition

    Directory of Open Access Journals (Sweden)

    Del Zotto Marzia

    2007-04-01

    Full Text Available Abstract Background Neuroimaging and neuropsychological literature show functional dissociations in brain activity during processing of stimuli belonging to different semantic categories (e.g., animals, tools, faces, places, but little information is available about the time course of object perceptual categorization. The aim of the study was to provide information about the timing of processing stimuli from different semantic domains, without using verbal or naming paradigms, in order to observe the emergence of non-linguistic conceptual knowledge in the ventral stream visual pathway. Event related potentials (ERPs were recorded in 18 healthy right-handed individuals as they performed a perceptual categorization task on 672 pairs of images of animals and man-made objects (i.e., artifacts. Results Behavioral responses to animal stimuli were ~50 ms faster and more accurate than those to artifacts. At early processing stages (120–180 ms the right occipital-temporal cortex was more activated in response to animals than to artifacts as indexed by posterior N1 response, while frontal/central N1 (130–160 showed the opposite pattern. In the next processing stage (200–260 the response was stronger to artifacts and usable items at anterior temporal sites. The P300 component was smaller, and the central/parietal N400 component was larger to artifacts than to animals. Conclusion The effect of animal and artifact categorization emerged at ~150 ms over the right occipital-temporal area as a stronger response of the ventral stream to animate, homomorphic, entities with faces and legs. The larger frontal/central N1 and the subsequent temporal activation for inanimate objects might reflect the prevalence of a functional rather than perceptual representation of manipulable tools compared to animals. Late ERP effects might reflect semantic integration and cognitive updating processes. Overall, the data are compatible with a modality-specific semantic memory

  10. Induction and separation of motion artifacts in EEG data using a mobile phantom head device

    Science.gov (United States)

    Oliveira, Anderson S.; Schlink, Bryan R.; Hairston, W. David; König, Peter; Ferris, Daniel P.

    2016-06-01

    Objective. Electroencephalography (EEG) can assess brain activity during whole-body motion in humans but head motion can induce artifacts that obfuscate electrocortical signals. Definitive solutions for removing motion artifact from EEG have yet to be found, so creating methods to assess signal processing routines for removing motion artifact are needed. We present a novel method for investigating the influence of head motion on EEG recordings as well as for assessing the efficacy of signal processing approaches intended to remove motion artifact. Approach. We used a phantom head device to mimic electrical properties of the human head with three controlled dipolar sources of electrical activity embedded in the phantom. We induced sinusoidal vertical motions on the phantom head using a custom-built platform and recorded EEG signals with three different acquisition systems while the head was both stationary and in varied motion conditions. Main results. Recordings showed up to 80% reductions in signal-to-noise ratio (SNR) and up to 3600% increases in the power spectrum as a function of motion amplitude and frequency. Independent component analysis (ICA) successfully isolated the three dipolar sources across all conditions and systems. There was a high correlation (r > 0.85) and marginal increase in the independent components’ (ICs) power spectrum (˜15%) when comparing stationary and motion parameters. The SNR of the IC activation was 400%-700% higher in comparison to the channel data SNR, attenuating the effects of motion on SNR. Significance. Our results suggest that the phantom head and motion platform can be used to assess motion artifact removal algorithms and compare different EEG systems for motion artifact sensitivity. In addition, ICA is effective in isolating target electrocortical events and marginally improving SNR in relation to stationary recordings.

  11. N3DFix: an Algorithm for Automatic Removal of Swelling Artifacts in Neuronal Reconstructions.

    Science.gov (United States)

    Conde-Sousa, Eduardo; Szücs, Peter; Peng, Hanchuan; Aguiar, Paulo

    2017-01-01

    It is well established that not only electrophysiology but also morphology plays an important role in shaping the functional properties of neurons. In order to properly quantify morphological features it is first necessary to translate observational histological data into 3-dimensional geometric reconstructions of the neuronal structures. This reconstruction process, independently of being manual or (semi-)automatic, requires several preparation steps (e.g. histological processing) before data acquisition using specialized software. Unfortunately these processing steps likely produce artifacts which are then carried to the reconstruction, such as tissue shrinkage and formation of swellings. If not accounted for and corrected, these artifacts can change significantly the results from morphometric analysis and computer simulations. Here we present N3DFix, an open-source software which uses a correction algorithm to automatically find and fix swelling artifacts in neuronal reconstructions. N3DFix works as a post-processing tool and therefore can be used in either manual or (semi-)automatic reconstructions. The algorithm's internal parameters have been defined using a "ground truth" dataset produced by a neuroanatomist, involving two complementary manual reconstruction procedures: in the first, neuronal topology was faithfully reconstructed, including all swelling artifacts; in the second procedure a meticulous correction of the artifacts was manually performed directly during neuronal tracing. The internal parameters of N3DFix were set to minimize the differences between manual amendments and the algorithm's corrections. It is shown that the performance of N3DFix is comparable to careful manual correction of the swelling artifacts. To promote easy access and wide adoption, N3DFix is available in NEURON, Vaa3D and Py3DN.

  12. High Line

    DEFF Research Database (Denmark)

    Kiib, Hans

    2015-01-01

    At just over 10 meters above street level, the High Line extends three kilometers through three districts of Southwestern Manhattan in New York. It consists of simple steel construction, and previously served as an elevated rail line connection between Penn Station on 34th Street and the many....... The High Line project has been carried out as part of an open conversion strategy. The result is a remarkable urban architectural project, which works as a catalyst for the urban development of Western Manhattan. The greater project includes the restoration and reuse of many old industrial buildings...... in close proximity to the park bridge and new projects being added to fit the context. The outcome is a conglomeration of non-contemporary urban activities along the High Line, where mechanical workshops, small wholesale stores. etc. mix with new exclusive residential buildings, eminent cafés...

  13. High Line

    DEFF Research Database (Denmark)

    Kiib, Hans

    2015-01-01

    in close proximity to the park bridge and new projects being added to fit the context. The outcome is a conglomeration of non-contemporary urban activities along the High Line, where mechanical workshops, small wholesale stores. etc. mix with new exclusive residential buildings, eminent cafés......At just over 10 meters above street level, the High Line extends three kilometers through three districts of Southwestern Manhattan in New York. It consists of simple steel construction, and previously served as an elevated rail line connection between Penn Station on 34th Street and the many...... factories and warehouses on Gansevoort Street. Today the High Line is a beautiful park covered with new tiles, viewing platforms and smaller recreational areas. The park bridge has simple, uniform, urban fittings and features a variety of flowering plants, grasses, shrubs and trees from around the world...

  14. K-space model of motion artifacts in synthetic transmit aperture ultrasound imaging

    DEFF Research Database (Denmark)

    Nikolov, Svetoslav; Jensen, Jørgen Arendt

    2003-01-01

    and leads to distortions in the image. In order to develop motion compensation and/or velocity estimation algorithms a thorough and intuitive understanding of the nature of motion artifacts is needed. This paper proposes a simple 2D broad band model for STA images, based on the acquisition procedure...... resolution image as a sum of rotated PSFs of a single LRI. The approximation is validated with a Field II simulation. The model predicts and explains the motion artifacts, and gives an intuitive feeling of what would happen for different velocities....

  15. Reduction of Artifacts in Images from MR Truncated Data Using Singularity Spectrum Analysis

    Institute of Scientific and Technical Information of China (English)

    骆建华; 庄天戈

    2000-01-01

    In this paper, the theory of signal singularity spectrum analysis (SSA) is proposed. Using SSA theory, a new method is presented to reduce truncation artifacts in magnetic resonance (MR) image due to truncated spectrum data. In the scheme, after detecting signal singularity locations using wavelet analysis in spectrum domain, SSA mathematic model is constructed, where weight coefficients are determined by known truncated spectrum data. Then, the remainder of the truncated spectrum can be obtained using SSA. Experiment and simulation results show that the SSA method will produce fewer artifacts in MR image from truncated spectrum than existing methods.

  16. Intrasite spatial variation of the Omo Kibish Middle Stone Age assemblages: artifact refitting and distribution patterns.

    Science.gov (United States)

    Sisk, Matthew L; Shea, John J

    2008-09-01

    The middle-late Pleistocene Kibish Formation of the Lower Omo Valley (Ethiopia) contains some of the oldest dated Homo sapiens fossils. Archaeological excavations at the Omo Kibish between 2002 and 2003 recovered numerous stone tools from extensive horizontal exposures of two sites, KHS (dated to 195+/-5 kyr) and BNS (dated to at least 104+/-7 kyr). Analysis of artifact distributions, lithic-debris densities, and refitting artifact sets sheds light on site-formation processes. Both localities reveal weak patterns of differentiation, and BNS seems to have a preferred refit orientation.

  17. Pitfalls and artifacts in the interpretation of oncologic PET/CT of the chest

    Science.gov (United States)

    Meirelles, Gustavo de Souza Portes; Capobianco, Julia; de Oliveira, Marco Antônio Condé

    2017-01-01

    PET/CT is widely used for the evaluation of patients with thoracic malignancies. Although the levels of 18F-fluorodeoxyglucose (FDG) uptake are usually high in neoplastic diseases, they can also be physiological, due to artifacts. In addition, FDG uptake can occur in benign conditions such as infectious, inflammatory, and iatrogenic lesions. Furthermore, some malignant tumors, such as adenocarcinoma in situ (formerly known as bronchoalveolar carcinoma) and carcinoid tumors, may not show FDG uptake. Here, we illustrate the main pitfalls and artifacts in the interpretation of the results of oncologic PET/CT of the chest, outlining strategies for avoiding misinterpretation. PMID:28298733

  18. Specimens with an Artifact Appearing as 'Three Spines' in Milnesium tardigradum var. trispinosa Rahm, 1931 (Tardigrada).

    Science.gov (United States)

    Suzuki, Atsushi C

    2016-08-01

    Milnesium tardigradum trispinosa Rahm, 1931 is characterized by its three spines at the posterior end of the animal, but has never been reported since its original description. Among mounted specimens of Milnesium sp. from Japan and M. tardigradum s. s. from France, several cases with these 'three spines' were observed. In these samples, the character was formed by an artifact of the fixation process. Images of these specimens show such a striking similarity to Milnesium tardigradum trispinosa that this taxon must be considered as having been erroneously established as a result of misinterpretation of an artifact and no longer valid.

  19. Light-scattering-induced artifacts in a complex polymer gel dosimetry phantom.

    Science.gov (United States)

    Bosi, Stephen G; Naseri, Pourandokht; Baldock, Clive

    2009-05-01

    Certain polymer gels become turbid on exposure to ionizing radiation, a property exploited in medical dosimetry to produce three-dimensional dose maps for radiotherapy. These maps can be read using optical computed tomography (CT). A test phantom of complex shape ("layered tube") was developed to investigate the optical properties of polymer gel dosimeters when read using optical CT. Extinction coefficient profiles from tomographically reconstructed slices of the phantom exhibited several artifacts. A simple model invoking scattered light in the gel was able to account for all artifacts, which in a real dosimeter may have been mistaken for other phenomena, resulting in incorrect readings of dose.

  20. The combined technique for detection of artifacts in clinical electroencephalograms of sleeping newborns.

    Science.gov (United States)

    Schetinin, Vitaly; Schult, Joachim

    2004-03-01

    In this paper, we describe a new method combining the polynomial neural network and decision tree techniques in order to derive comprehensible classification rules from clinical electroencephalograms (EEGs) recorded from sleeping newborns. These EEGs are heavily corrupted by cardiac, eye movement, muscle, and noise artifacts and, as a consequence, some EEG features are irrelevant to classification problems. Combining the polynomial network and decision tree techniques, we discover comprehensible classification rules while also attempting to keep their classification error down. This technique is shown to out-perform a number of commonly used machine learning technique applied to automatically recognize artifacts in the sleep EEGs.

  1. Pitfalls and artifacts in the interpretation of oncologic PET/CT of the chest

    Energy Technology Data Exchange (ETDEWEB)

    Meirelles, Gustavo de Souza Portes; Capobianco, Julia; Oliveira, Marco Antonio Conde de, E-mail: gustavo.meirelles@grupofleury.com.br [Grupo Fleury, Sao Paulo, SP (Brazil)

    2017-01-15

    PET/CT is widely used for the evaluation of patients with thoracic malignancies. Although the levels of {sup 18}F-fluorodeoxyglucose (FDG) uptake are usually high in neoplastic diseases, they can also be physiological, due to artifacts. In addition, FDG uptake can occur in benign conditions such as infectious, inflammatory, and iatrogenic lesions. Furthermore, some malignant tumors, such as adenocarcinoma in situ (formerly known as bronchoalveolar carcinoma) and carcinoid tumors, may not show FDG uptake. Here, we illustrate the main pitfalls and artifacts in the interpretation of the results of oncologic PET/CT of the chest, outlining strategies for avoiding misinterpretation. (author)

  2. Discovery of the Earliest Synthetic Carborundum (SiC in Neolithic Jade Artifacts in Eastern China

    Directory of Open Access Journals (Sweden)

    Su-Jung Chou

    2014-01-01

    Full Text Available Using Raman microscopy and scanning electron microscopy we have successfully identified, for the first time, synthetic silicon carbide (carborundum particles in 15 unearthed relics and assorted remains from five out of six Neolithic sites (~4000 - 7000 years b.p. in Eastern China. Because of its extreme hardness, silicon carbide was apparently employed in the manufacture of ancient jade artifacts presumably as an abrasive for polishing. We show that Neolithic people may have already used this synthetic material to carve and polish both jade and quartz artifacts, contributing to the blooming development of the jade culture throughout ancient China.

  3. Mastering the discrete Fourier transform in one, two or several dimensions pitfalls and artifacts

    CERN Document Server

    Amidror, Isaac

    2013-01-01

    The discrete Fourier transform (DFT) is an extremely useful tool that finds application in many different disciplines. However, its use requires caution. The aim of this book is to explain the DFT and its various artifacts and pitfalls and to show how to avoid these (whenever possible), or at least how to recognize them in order to avoid misinterpretations. This concentrated treatment of the DFT artifacts and pitfalls in a single volume is, indeed, new, and it makes this book a valuable source of information for the widest possible range of DFT users. Special attention is given to the one and

  4. Reduction of blooming artifacts in cardiac CT images by blind deconvolution and anisotropic diffusion filtering

    Science.gov (United States)

    Castillo-Amor, Angélica M.; Navarro-Navia, Cristian A.; Cadena-Bonfanti, Alberto J.; Contreras-Ortiz, Sonia H.

    2015-12-01

    Even though CT is an imaging technique that offers high quality images, limitations on its spatial resolution cause blurring in small objects with high contrast. This phenomenon is known as blooming artifact and affects cardiac images with small calcifications and stents. This paper describes an approach to reduce the blooming artifact and improve resolution in cardiac images using blind deconvolution and anisotropic diffusion filtering. Deconvolution increases resolution but reduces signal-to-noise ratio, and the anisotropic diffusion filter counteracts this effect without affecting the edges in the image.

  5. Online Artifact Removal for Brain-Computer Interfaces Using Support Vector Machines and Blind Source Separation

    Directory of Open Access Journals (Sweden)

    Sebastian Halder

    2007-01-01

    that are designed for online usage. In order to select a suitable BSS/ICA method, three ICA algorithms (JADE, Infomax, and FastICA and one BSS algorithm (AMUSE are evaluated to determine their ability to isolate electromyographic (EMG and electrooculographic (EOG artifacts into individual components. An implementation of the selected BSS/ICA method with SVMs trained to classify EMG and EOG artifacts, which enables the usage of the method as a filter in measurements with online feedback, is described. This filter is evaluated on three BCI datasets as a proof-of-concept of the method.

  6. Technical Note: On GAFChromic EBT-XD film and the lateral response artifact.

    Science.gov (United States)

    Lewis, David F; Chan, Maria F

    2016-02-01

    The new radiochromic film, GAFChromic EBT-XD, contains the same active material, lithium-10,12-pentacosadiynoate, as GAFChromic EBT3, but the crystalline form is different. This work investigates the effect of this change on the well-known lateral response artifact when EBT-XD film is digitized on a flatbed scanner. The dose response of a single production lot of EBT-XD was characterized by scanning an unexposed film plus a set of films exposed to doses between 2.5 and 50 Gy using 6 MV photons. To characterize the lateral response artifact, the authors used the unexposed film plus a subset of samples exposed to doses between 20 and 50 Gy. Digital images of these films were acquired at seven discrete lateral locations perpendicular to the scan direction on three Epson 10000XL scanners. Using measurements at the discrete lateral positions, the scanner responses were determined as a function of the lateral position of the film. From the data for each scanner, a set of coefficients were derived whereby measured response values could be corrected to remove the effects of the lateral response artifact. The EBT-XD data were analyzed as in their previous work and compared to results reported for EBT3 in that paper. For films scanned in the same orientation and having equal responses, the authors found that the lateral response artifact for EBT-XD and EBT3 films was remarkably similar. For both films, the artifact increases with increased net response. However, as EBT-XD is less sensitive than EBT3, a greater exposure dose is required to reach the same net response. On this basis, the lower sensitivity of EBT-XD relative to EBT3 results in less net response change for equal exposure and a reduction in the impact of the lateral response artifact. The shape of the crystalline active component in EBT-XD and EBT3 does not affect the fundamental existence of the lateral response artifact when the films are digitized on flatbed scanners. Owing its lower sensitivity, EBT-XD film

  7. Comparison of ring artifact removal methods using flat panel detector based CT images

    Directory of Open Access Journals (Sweden)

    Lee Soo Y

    2011-08-01

    Full Text Available Abstract Background Ring artifacts are the concentric rings superimposed on the tomographic images often caused by the defective and insufficient calibrated detector elements as well as by the damaged scintillator crystals of the flat panel detector. It may be also generated by objects attenuating X-rays very differently in different projection direction. Ring artifact reduction techniques so far reported in the literature can be broadly classified into two groups. One category of the approaches is based on the sinogram processing also known as the pre-processing techniques and the other category of techniques perform processing on the 2-D reconstructed images, recognized as the post-processing techniques in the literature. The strength and weakness of these categories of approaches are yet to be explored from a common platform. Method In this paper, a comparative study of the two categories of ring artifact reduction techniques basically designed for the multi-slice CT instruments is presented from a common platform. For comparison, two representative algorithms from each of the two categories are selected from the published literature. A very recently reported state-of-the-art sinogram domain ring artifact correction method that classifies the ring artifacts according to their strength and then corrects the artifacts using class adaptive correction schemes is also included in this comparative study. The first sinogram domain correction method uses a wavelet based technique to detect the corrupted pixels and then using a simple linear interpolation technique estimates the responses of the bad pixels. The second sinogram based correction method performs all the filtering operations in the transform domain, i.e., in the wavelet and Fourier domain. On the other hand, the two post-processing based correction techniques actually operate on the polar transform domain of the reconstructed CT images. The first method extracts the ring artifact template

  8. A line-based visualization of code evolution

    OpenAIRE

    Voinea, SL Lucian; Telea, AC Alexandru; Wijk, van, M.N.

    2005-01-01

    The source code of software systems changes many times during the system lifecycle. We study how developers can get insight in these changes in order to understand the project context and the product artifacts. For this we propose new techniques for code evolution representation and visualization interaction from a version-centric perspective. Central to our approach is a line-based display of the changing code, where each file version is shown as a column and the horizontal axis shows time. ...

  9. 75 FR 57825 - Culturally Significant Objects Imported for Exhibition Determinations: “Artifacts From Auschwitz...

    Science.gov (United States)

    2010-09-22

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF STATE Culturally Significant Objects Imported for Exhibition Determinations: ``Artifacts From Auschwitz-Birkenau... of August 28, 2000, I hereby determine that the objects to be included in the exhibition...

  10. Teachers Sharing Artifacts from Students’ High-level Use of ICT in Science

    DEFF Research Database (Denmark)

    Nielsen, Birgitte Lund

    to support the success of integrating technology. Experiences from a large-scale, long-term TPD project for primary and secondary science teachers supporting the teachers in trying out innovative practices and new ICT tools in own classes, and in sharing artifacts from these trials in teacher networks...

  11. Effect of motion artifacts and their correction on near-infrared spectroscopy oscillation data

    DEFF Research Database (Denmark)

    Selb, Juliette; Yücel, Meryem A; Phillip, Dorte;

    2015-01-01

    Functional near-infrared spectroscopy is prone to contamination by motion artifacts (MAs). Motion correction algorithms have previously been proposed and their respective performance compared for evoked rain activation studies. We study instead the effect of MAs on "oscillation" data which...

  12. Split-remerge method for eliminating processing window artifacts in recursive hierarchical segmentation

    Science.gov (United States)

    Tilton, James C. (Inventor)

    2010-01-01

    A method, computer readable storage, and apparatus for implementing recursive segmentation of data with spatial characteristics into regions including splitting-remerging of pixels with contagious region designations and a user controlled parameter for providing a preference for merging adjacent regions to eliminate window artifacts.

  13. Preparing Special Education Mentors Using Classroom Artifacts as a Vehicle for Learning about Teaching

    Science.gov (United States)

    Parker-Katz, Michelle; Hughes, Marie Tejero

    2008-01-01

    The authors examine a project that focuses on preparing special educators to mentor pre-service teachers throughout their preparation program, instead of mostly at the end of their program. Through use of classroom literacy artifacts, mentors are prepared in how to guide novices as they transition through coursework and into classroom practice.…

  14. Literacy Artifacts and the Semiotic Landscape of a Spanish Secondary School

    Science.gov (United States)

    Poveda, David

    2012-01-01

    In this article, I examine literacy artifacts placed by students in different locations of a state-run secondary school in the city of Madrid, Spain. The data were gathered as part of a two-year long multilevel ethnography focused on the social and academic trajectories of immigrant students in Spanish compulsory secondary education. The analysis…

  15. Connecting agents and artifacts in CSCL: Towards a rationale of mutual shaping

    NARCIS (Netherlands)

    Overdijk, Maarten; Van Diggelen, Wouter; Kirschner, Paul A.; Baker, Michael

    2012-01-01

    Overdijk, M., Van Diggelen, W., Kirschner, P. A., & Baker, M. (2012). Connecting agents and artifacts in CSCL: Towards a rationale of mutual shaping. International Journal of Computer-Supported Collaborative Learning, 7, 193-210. doi:10.1007/s11412-012-9143-2

  16. Connecting Agents and Artifacts in CSCL: Towards a Rationale of Mutual Shaping

    Science.gov (United States)

    Overdijk, Maarten; van Diggelen, Wouter; Kirschner, Paul A.; Baker, Michael

    2012-01-01

    Studying how collaborative activity takes shape interactionally in the context of technological settings is one of the main challenges in the field of Computer-Supported Collaborative Learning (CSCL). It requires us, amongst other things, to look into the "black box" of how technical artifacts are brought into use, or rather, how they are attuned…

  17. Image artifacts from MR-based attenuation correction in clinical, whole-body PET/MRI

    DEFF Research Database (Denmark)

    Keller, Sune H; Holm, Søren; Hansen, Adam E;

    2013-01-01

    Integrated whole-body PET/MRI tomographs have become available. PET/MR imaging has the potential to supplement, or even replace combined PET/CT imaging in selected clinical indications. However, this is true only if methodological pitfalls and image artifacts arising from novel MR-based attenuation...

  18. 3D Pseudocontinuous arterial spin labeling in routine clinical practice: A review of clinically significant artifacts.

    Science.gov (United States)

    Amukotuwa, Shalini A; Yu, Caroline; Zaharchuk, Gregory

    2016-01-01

    Arterial spin labeling (ASL) is a completely noninvasive magnetic resonance imaging (MRI) perfusion method for quantitatively measuring cerebral blood flow utilizing magnetically labeled arterial water. Advances in the technique have enabled the major MRI vendors to make the sequence available to the clinical neuroimaging community. Consequently, ASL is being increasingly incorporated into the routine neuroimaging protocol. Although a variety of ASL techniques are available, the ISMRM Perfusion Study Group and the European ASL in Dementia Consortium have released consensus guidelines recommending standardized implementation of 3D pseudocontinuous ASL with background suppression. The purpose of this review, aimed at the large number of neuroimaging clinicians who have either no or limited experience with this 3D pseudocontinuous ASL, is to discuss the common and clinically significant artifacts that may be encountered with this technique. While some of these artifacts hinder accurate interpretation of studies, either by degrading the images or mimicking pathology, there are other artifacts that are of clinical utility, because they increase the conspicuity of pathology. Cognizance of these artifacts will help the physician interpreting ASL to avoid potential diagnostic pitfalls, and increase their level of comfort with the technique.

  19. Temperature artifacts produced by thermocouples used in conjunction with 1 and 3 MHz ultrasound.

    Science.gov (United States)

    Waterman, F M; Leeper, J B

    1990-01-01

    The relative temperature artifacts produced by a selection of commercially available thermocouples and catheters were evaluated in radiation bolus and beef phantoms heated by 1 and 3 MHz continuous ultrasound. The thermocouples included a 23 gauge needle microprobe inserted directly into the phantoms, polyurethane-sheathed, Teflon-sheathed, and exposed-tip thermocouples, each inserted into a 19 gauge polyurethane closed-end catheter, a multisensor Teflon-sheathed probe inserted into a 16 gauge polyurethane catheter and a Teflon-sheathed single-sensor probe without a catheter. The needle microprobe and the polyurethane-sheathed thermocouple produce equivalent artifacts. The artifacts produced by the Teflon and exposed-tip thermocouples are 1.4 +/- 0.3 times greater, that produced by the multisensor Teflon-sheathed probe is 2.1 +/- 0.3 times greater, and that produced by the Teflon-sheathed thermocouple without a catheter is 2.3 +/- 0.4 times greater. The results in the beef phantom indicate that the needle microprobe and polyurethane-sheathed thermocouple both produce artifacts of 0.7 +/- 0.1 degree in tissue at an SAR of 100 W/kg.

  20. Removal of ring artifacts in computed tomographic imaging using iterative center weighted median filter.

    Science.gov (United States)

    Sadi, Fazle; Lee, Soo Yeol; Hasan, Md Kamrul

    2010-01-01

    A new iterative center weighted median filter (ICWMF) for ring artifact reduction from the micro-computed tomographic (micro-CT) image is proposed in this paper. The center weight of the median filter is computed based on the characteristic of the ring artifact in the mean curve of the projection data. The filter operates on the deviation of the mean curve to smooth the ring generating peaks and troughs iteratively while preserving the details due to image. A convergence criterion for the iterative algorithm is determined from the distribution of the local deviation computed from the mean curve deviation. The estimate of the mean curve obtained using the ICWMF is used to correct the ring corrupted projection data from which reconstruction gives the ring artifact suppressed micro-CT image. Test results on both the synthetic and real images demonstrate that the ring artifacts can be more effectively suppressed using our method as compared to other ring removal techniques reported in the literature. 2009 Elsevier Ltd. All rights reserved.