Energy consumption and stocks of energy-converting artefacts

International Nuclear Information System (INIS)

Bladh, Mats

2012-01-01

The development of total energy consumption is important in a world with limited resources. It is the result of two basic tendencies working in opposite directions: growth in number and in use (such as more cars and driving more) and improvements in energy efficiency (such as more fuel-efficient engines). Since the 1970s growth of energy consumption has slowed down in Sweden. This means that increasing supply has been counteracted by measures improving overall energy efficiency to a larger degree than before. How can long-term development in energy consumption be analysed? This paper proposes a focus on stocks of energy-converting artefacts as a tool for such analyses. In order to show the fruitfulness of this approach, historical data on cars, dwellings and lamps in Sweden are used. Results from the cases in this paper show considerable gains of efficiency in fuel consumption in private cars and heating efficiency in multi-dwelling houses. Demographic factors are important for the outcome. The approach seems to promise a way to analyse energy efficiency that captures both promoting and counteracting factors at both the micro and macro level. - Highlights: ► Growth of energy consumption slowed down in the 1970s, a break in the long-run trend. ► Balance between growth and efficiency factors changes over time and areas of use. ► Savings in heating were not taken back, while those for cars were. ► Focus on stocks of artefacts is a promising tool for analyses. ► Incremental changes within existing stocks can be as big as radical changes.

Multiple height calibration artefact for 3D microscopy

DEFF Research Database (Denmark)

De Chiffre, Leonardo; Carli, Lorenzo; Eriksen, Rasmus Solmer

2011-01-01

A novel artefact for calibration of the height in 3D microscopy is presented. The artefact comprises three steps having a common vertical axis, which allows z-coordinate calibration at different magnifications without requiring repositioning. The artefact is suitable for transferring traceability...... to 3D techniques at the micrometer and nanometer scale, e.g. 3D SEM, confocal microscopes etc. Two different series of samples were fabricated using EDM with three steps of 2–5–7μm, and 20–50–70μm, respectively, from a 3mm diameter carbide wire. The artefact steps were calibrated on a stylus instrument...

Neutron activation analysis of artefacts

International Nuclear Information System (INIS)

Mohd Suhaimi Hamzah; Shamsiah Abd Rahman

2004-01-01

The paper discussed the utilization of neutron activation analysis in this field. NAA, an analytical technique which analyzing the elements in the sample without any chemical treatment. It is sensitive and accurate. Archaeological objects i.e. ceramics, historical building materials, metals, etc can be analyze with this technique. The analysis results were presented in form of characterization of the artefacts in chemical profiles, which can present the information of the origin of the artefacts as well as it originality. (Author)

Experiential Role of Artefacts in Cooperative Design

NARCIS (Netherlands)

Vyas, Dhaval; Heylen, Dirk K.J.; Nijholt, Antinus; van der Veer, Gerrit C.; Caroll, J.M.

2009-01-01

The role of material artefacts in supporting distributed and co-located work practices has been well acknowledged within the HCI and CSCW research. In this paper, we show that in addition to their ecological, coordinative and organizational support, artefacts also play an ‘experiential’ role. In

Replica calibration artefacts for optical 3D scanning of micro parts

DEFF Research Database (Denmark)

De Chiffre, Leonardo; Carmignato, S.; Cantatore, Angela

2009-01-01

This work deals with development of calibration artefacts produced by using hard replica materials, achieving high quality geometrical reproduction of suitable reference artefacts, high stability, and high surface cooperativeness. An investigation was carried out using a replica material for dental...... applications to reproduce the geometry of a step artefact, a miniature step gauge, and a curve standard for optical measuring machines. The replica artefacts were calibrated using a tactile coordinate measuring machine and measured on two different optical scanners. Replication quality and applicability...... of the artefacts to verify the accuracy of optical measurements as well as thermal expansion coefficient and stability of the replica artefacts over time were documented....

Leadership identity : using artefacts (and storytelling) to discover new insights.

OpenAIRE

Watton, Emma Louisa; Parry, Ken

2016-01-01

Artefacts are used in management education to reflect upon the experiences of participants. Story-telling has a leadership influence that is long recognised in the leadership literature. However, artefacts and story-telling have not been used concurrently in leadership and management development programmes. We used artefacts combined with story-telling to help participants understand their leadership identity. Louisa’s story and artefact are the basis of this research. We found that the story...

Investigating effects of different artefact types on motor imagery BCI

DEFF Research Database (Denmark)

Frølich, Laura; Winkler, Irene; Muller, Klaus-Robert

2015-01-01

Artefacts in recordings of the electroencephalogram (EEG) are a common problem in Brain-Computer Interfaces (BCIs). Artefacts make it difficult to calibrate from training sessions, resulting in low test performance, or lead to artificially high performance when unintentionally used for BCI control...... that muscle, but not ocular, artefacts adversely affect BCI performance when all 119 EEG channels are used. Artefacts have little influence when using 48 centrally located EEG channels in a configuration previously found to be optimal....

Indigenous african artefacts: Can they serve as tangible programming objects?

CSIR Research Space (South Africa)

Smith, Andrew C

2010-05-01

Full Text Available , African artefacts, Interaction design. 1. Introduction The aim of our research is to investigate the possible use of physical artefacts as tangible programming objects with the purpose of instilling an interest in programming amongst regional tribes... in Africa. Physical artefacts are hand-crafted objects made by community members. We envisage a simple computing system that derives its input from the manipulation of artefacts as opposed to the use of a keyboard and mouse. In order to do so...

Organisational learning is crystallised into artefacts

DEFF Research Database (Denmark)

Bertelsen, Olav Wedege

1996-01-01

In this note I understand organisational learning in terms of manifest crystallisation of collective experience into artefacts, and I attempt to integrate an engineering and an emancipatory perspective. A Danish music festival serves as an example.......In this note I understand organisational learning in terms of manifest crystallisation of collective experience into artefacts, and I attempt to integrate an engineering and an emancipatory perspective. A Danish music festival serves as an example....

Assessing MRI susceptibility artefact through an indicator of image distortion

Directory of Open Access Journals (Sweden)

Illanes Alfredo

2016-09-01

Full Text Available Susceptibility artefacts in magnetic resonance imaging (MRI caused by medical devices can result in a severe degradation of the MR image quality. The quantification of susceptibility artefacts is regulated by the ASTM standard which defines a manual method to assess the size of an artefact. This means that the estimated artefact size can be user dependent. To cope with this problem, we propose an algorithm to automatically quantify the size of such susceptibility artefacts. The algorithm is based on the analysis of a 3D surface generated from the 2D MR images. The results obtained by the automatic algorithm were compared to the manual measurements performed by study participants. The results show that the automatic and manual measurements follow the same trend. The clear advantage of the automated algorithm is the absence of the inter- and intra-observer variability. In addition, the algorithm also detects the slice containing the largest artefact which was not the case for the manual measurements.

Artefacts that talk

DEFF Research Database (Denmark)

Hasse, Cathrine

2013-01-01

The article takes up the notion of artefacts as tools and signs and discusses how socially assistive robots impact professional work life and professional identities as multistable active change agents. It argues for a multistable understanding of tools as signs, building on a combination of post...

The materiality of materials and artefacts used in science classrooms

DEFF Research Database (Denmark)

Cowie, Bronwen; Otrel-Cass, Kathrin; Moreland, Judy

Material objects and artefacts receive limited attention in science education (Roehl, 2012) though they shape emerging interactions. This is surprising given science has material and a social dimensions (Pickering, 1995) whereby new knowledge develops as a consensus explanation of natural phenomena...... that is mediated significantly through materials and instruments used. Here we outline the ways teachers deployed material objects and artefacts by identifying their materiality to provide scenarios and resources (Roth, 2005) for interactions. Theoretical framework We use Ingold's (2011) distinction between...... materials as natural objects in this world and artefacts as manmade objects. We are aware that in a classroom material objects and artefacts shape, and are shaped by classroom practice through the way they selectively present scientific explanations. However, materials and artefacts have no intrinsic...

3D artefact for concurrent scale calibration in Computed Tomography

DEFF Research Database (Denmark)

Stolfi, Alessandro; De Chiffre, Leonardo

2016-01-01

A novel artefact for calibration of the scale in 3D X-ray Computed Tomography (CT) is presented. The artefact comprises a carbon fibre tubular structure on which a number of reference ruby spheres are glued. The artefact is positioned and scanned together with the workpiece inside the CT scanner...

Possible artefacts in thin layer chromatography of tritium-labelled hydrocortisone

International Nuclear Information System (INIS)

Sofronie, E.

1982-12-01

Artefacts appearing in thin layer chromatography of tritium labelled hydrocortisone are reported. Evidences are presented that these artefacts cause misleading results concerning radiocheemical purity determiniation. Finally, it is reported a rapid and efficient chromatographic technique allowing the elimination of these artefacts and obtaining of an accurate value for radiochemical purity. (author)

Reducing the effects of metal artefact using high keV monoenergetic reconstruction of dual energy CT (DECT) in hip replacements

Energy Technology Data Exchange (ETDEWEB)

Lewis, Mark [Norfolk and Norwich University Hospital, Norwich (United Kingdom); Norwich Radiology Academy, Norwich (United Kingdom); Reid, Karen [Norfolk and Norwich University Hospital, Norwich (United Kingdom); Toms, Andoni P. [Norfolk and Norwich University Hospital and University of East Anglia, Norwich (United Kingdom)

2013-02-15

The aim of this study was to determine whether high keV monoenergetic reconstruction of dual energy computed tomography (DECT) could be used to overcome the effects of beam hardening artefact that arise from preferential deflection of low energy photons. Two phantoms were used: a Charnley total hip replacement set in gelatine and a Catphan 500. DECT datasets were acquired at 100, 200 and 400 mA (Siemens Definition Flash, 100 and 140 kVp) and reconstructed using a standard combined algorithm (1:1) and then as monoenergetic reconstructions at 10 keV intervals from 40 to 190 keV. Semi-automated segmentation with threshold inpainting was used to obtain the attenuation values and standard deviation (SD) of the streak artefact. High contrast line pair resolution and background noise were assessed using the Catphan 500. Streak artefact is progressively reduced with increasing keV monoenergetic reconstructions. Reconstruction of a 400 mA acquisition at 150 keV results in reduction in the volume of streak artefact from 65 cm{sup 3} to 17 cm{sup 3} (74 %). There was a decrease in the contrast to noise ratio (CNR) at higher tube voltages, with the peak CNR seen at 70-80 keV. High contrast spatial resolution was maintained at high keV values. Monoenergetic reconstruction of dual energy CT at increasing theoretical kilovoltages reduces the streak artefact produced by beam hardening from orthopaedic prostheses, accompanied by a modest increase in heterogeneity of background image attenuation, and decrease in contrast to noise ratio, but no deterioration in high contrast line pair resolution. (orig.)

Artefact specification, design, and production as a process of communication

DEFF Research Database (Denmark)

Galle, Per

1999-01-01

about communication as literal ‘transmission’ or ‘sharing’ of ideas. It is then explained how the initial artefact specification, the design representation, and ultimately the artefact itself can all be seen as symbolic expressions of ideas that are communicated, and it is shown how the conditions...... for the success of communication carry over to the artefact production process. The purpose of the analysis is to provide a conceptual background for the study of various aspects of artefact production, such as design, or the development of computer-based tools for collaborative design, product modelling...

Metal artefact reduction in MRI at both 1.5 and 3.0 T using slice encoding for metal artefact correction and view angle tilting

Science.gov (United States)

Reichert, M; Morelli, J N; Nittka, M; Attenberger, U; Runge, V M

2015-01-01

Objective: To compare metal artefact reduction in MRI at both 3.0 T and 1.5 T using different sequence strategies. Methods: Metal implants of stainless steel screw and plate within agarose phantoms and tissue specimens as well as three patients with implants were imaged at both 1.5 T and 3.0 T, using view angle tilting (VAT), slice encoding for metal artefact correction with VAT (SEMAC-VAT) and conventional sequence. Artefact reduction in agarose phantoms was quantitatively assessed by artefact volume measurements. Blinded reads were conducted in tissue specimen and human imaging, with respect to artefact size, distortion, blurring and overall image quality. Wilcoxon and Friedman tests for multiple comparisons and intraclass correlation coefficient (ICC) for interobserver agreement were performed with a significant level of p 3.0 T (p 3.0 T. Advances in knowledge: The feasibility of metal artefact reduction with SEMAC-VAT was demonstrated at 3.0-T MR. SEMAC-VAT significantly reduced metal artefacts at both 1.5 and 3.0 T. SEMAC-VAT allowed for better visualization of the tissue structures adjacent to the metal implants. SEMAC-VAT produced consistently better image quality in both tissue specimen and human imaging. PMID:25613398

Reduction of ring artefacts in high resolution micro-CT reconstructions

International Nuclear Information System (INIS)

Sijbers, Jan; Postnov, Andrei

2004-01-01

High resolution micro-CT images are often corrupted by ring artefacts, prohibiting quantitative analysis and hampering post processing. Removing or at least significantly reducing such artefacts is indispensable. However, since micro-CT systems are pushed to the extremes in the quest for the ultimate spatial resolution, ring artefacts can hardly be avoided. Moreover, as opposed to clinical CT systems, conventional correction schemes such as flat-field correction do not lead to satisfactory results. Therefore, in this note a simple but efficient and fast post processing method is proposed that effectively reduces ring artefacts in reconstructed μ-CT images. (note)

Dosimetric Evaluation of Metal Artefact Reduction using Metal Artefact Reduction (MAR) Algorithm and Dual-energy Computed Tomography (CT) Method

Science.gov (United States)

Laguda, Edcer Jerecho

Purpose: Computed Tomography (CT) is one of the standard diagnostic imaging modalities for the evaluation of a patient's medical condition. In comparison to other imaging modalities such as Magnetic Resonance Imaging (MRI), CT is a fast acquisition imaging device with higher spatial resolution and higher contrast-to-noise ratio (CNR) for bony structures. CT images are presented through a gray scale of independent values in Hounsfield units (HU). High HU-valued materials represent higher density. High density materials, such as metal, tend to erroneously increase the HU values around it due to reconstruction software limitations. This problem of increased HU values due to metal presence is referred to as metal artefacts. Hip prostheses, dental fillings, aneurysm clips, and spinal clips are a few examples of metal objects that are of clinical relevance. These implants create artefacts such as beam hardening and photon starvation that distort CT images and degrade image quality. This is of great significance because the distortions may cause improper evaluation of images and inaccurate dose calculation in the treatment planning system. Different algorithms are being developed to reduce these artefacts for better image quality for both diagnostic and therapeutic purposes. However, very limited information is available about the effect of artefact correction on dose calculation accuracy. This research study evaluates the dosimetric effect of metal artefact reduction algorithms on severe artefacts on CT images. This study uses Gemstone Spectral Imaging (GSI)-based MAR algorithm, projection-based Metal Artefact Reduction (MAR) algorithm, and the Dual-Energy method. Materials and Methods: The Gemstone Spectral Imaging (GSI)-based and SMART Metal Artefact Reduction (MAR) algorithms are metal artefact reduction protocols embedded in two different CT scanner models by General Electric (GE), and the Dual-Energy Imaging Method was developed at Duke University. All three

Ringing Artefact Reduction By An Efficient Likelihood Improvement Method

Science.gov (United States)

Fuderer, Miha

1989-10-01

In MR imaging, the extent of the acquired spatial frequencies of the object is necessarily finite. The resulting image shows artefacts caused by "truncation" of its Fourier components. These are known as Gibbs artefacts or ringing artefacts. These artefacts are particularly. visible when the time-saving reduced acquisition method is used, say, when scanning only the lowest 70% of the 256 data lines. Filtering the data results in loss of resolution. A method is described that estimates the high frequency data from the low-frequency data lines, with the likelihood of the image as criterion. It is a computationally very efficient method, since it requires practically only two extra Fourier transforms, in addition to the normal. reconstruction. The results of this method on MR images of human subjects are promising. Evaluations on a 70% acquisition image show about 20% decrease of the error energy after processing. "Error energy" is defined as the total power of the difference to a 256-data-lines reference image. The elimination of ringing artefacts then appears almost complete..

Reduction of artefacts due to missing projections using OSEM

International Nuclear Information System (INIS)

Hutton, B.F.; Kyme, A.; Choong, K.

2002-01-01

Full text: It is well recognised that missing or corrupted projections can result in artefacts. This occasionally occurs due to errors in data transfer from acquisition memory to disk. A possible approach for reducing these artefacts was investigated, Using ordered subsets expectation maximization (OSEM) the iterative reconstruction proceeds by progressively including additional projections until a single iteration is complete. Clinically useful results can be obtained using a small subset size in a single iteration. Stopping prior to the complete iteration so as to avoid inclusion of missing or corrupted data should provide a 'partial' reconstruction with minimal artefacts. To test this hypothesis projections were selectively removed from a complete data set (2, 4, 8, 12 adjacent projections) and reconstructions were performed using both filtered back projection (FBP) and OSEM. To maintain a constant number of sub-iterations in OSEM an equal number of duplicate projections were substituted for the missing projections. Both 180 and 360 degrees reconstructions with missing data were compared with reconstruction for the complete data using sum of absolute differences. Results indicate that missing data causes artefacts for both FBP and OSEM however the severity of artefacts is significantly reduced using OSEM. The effect of missing data is generally greater for 180 degrees acquisition. OSEM is recommended for minimising reconstruction artefacts due to missing projections. Copyright (2002) The Australian and New Zealand Society of Nuclear Medicine Inc

Basic artefacts of diagnostic imaging by the magnetic resonance method

International Nuclear Information System (INIS)

Vitak, T.; Seidl, Z.; Obenberger, J.; Vaneckova, M.; Danes, J.; Krasensky, J.; Peterkova, V

2000-01-01

Artefacts in diagnostic imaging are defined as a geometric or anatomic misrepresentation of the reality by the image formed. The article deals with artefacts due to field and frequency shifts, in particular due to the water-fat chemical shift and due to magnetic susceptibility. The physical nature of the artefacts is explained and their diagnostic significance is discussed. (P.A.)

GIS as an Artefact in Geography Education: Some Future Challenges

DEFF Research Database (Denmark)

Madsen, Lene Møller; Winsløw, Carl

2007-01-01

Geographers have always used a variety of physical artefacts e.g. a pluviometer, a map, or a globe as tools to perform their profession. Each of these artefacts has in different ways shaped our ways of being and becoming geographers. Not only have they shaped how we learn but also what we learn. ...... this artefact offers to education and teaching....

On what is made : instruments, products and natural kinds of artefacts

NARCIS (Netherlands)

Houkes, W.N.; Vermaas, P.E.; Franssen, M.; Kroes, P.; Reydon, T.A.C.; Vermaas, P.E.

2014-01-01

Debates in the metaphysics of artefacts typically start from the observation that technical artefacts result from intentional production and then focus immediately on the issue whether this ‘mind-dependence’ undermines claims that artefacts exist or come in natural or real kinds. We aim to add

Emergent Artefacts of Ethnography and Processual Engagements of design

DEFF Research Database (Denmark)

Wallace, Jamie

2012-01-01

Relating to processes of design and creativity, the use of artefacts are contrasted between two different disciplines. Pointing to possible challenges, the study considers how collaborative innovation depends upon the interplay between entwined and emergent artefact worlds and their related skill...

Artefacts and Troubleshooting. Appendix I

Energy Technology Data Exchange (ETDEWEB)

Busemann Sokole, E. [Department of Nuclear Medicine, Academic Medical Center, Amsterdam (Netherlands); Forwood, N. J. [Department of Nuclear Medicine, Royal North Shore Hospital, Sydney (Australia)

2014-12-15

Troubleshooting refers to the process of recognizing and identifying the cause of an artefact, a malfunction or a problem in an instrument. The problem could be immediately obvious, for example, the instrument does not work at all or a particular component stops working (such as the computer, the mechanism for whole body scanning or the automatic mechanism for collimator exchange). The malfunction could also be less obvious, and be recognized only by an abnormality in the expected result (such as the pattern formed by a defective photomultiplier tube (PMT) in the gamma camera clinical or quality control (QC) image or an unexpected calibration result in a radionuclide dose calibrator). Such an abnormality is generally referred to as an artefact, in particular, when observed in images.

Explicating the Sustainable Design of Technical Artefacts

DEFF Research Database (Denmark)

Vissonova, Karina

2016-01-01

afforded by the properties of artefacts. The study is a conceptual analysis and as such belongs to the field of epistemology of design. It offers three contributions to the design discipline: (1) a proposition of the definition of the sustainable design kind; (2) a proposition of the concept of technical......Sustainable design of technical artefacts is referred to as if it were a kind of design with some specific characteristics. However, in design research and practice alike, there appears to be a lack of shared conceptions of what such a design might entail. Furthermore, we have no clear grounds...... for evaluating what makes the sustainable design solutions permissible. The lack of shared conceptions is largely due to ambiguities associated with the notion of sustainability. In response to these challenges, the aim of my study is to offer a definition of sustainable design of technical artefacts. I argue...

Radiocarbon dating of iron artefacts

Energy Technology Data Exchange (ETDEWEB)

Cresswell, R. [Australian National Univ., Canberra, ACT (Australia). Dept. of Nuclear Physics

1997-12-31

Iron artefacts are generally dated by association or on stylistic grounds. This may not give a true indication of the date of manufacture, or may not be possible if the piece is out of context, ambiguous in style, or a copy. Obtaining a direct date on the artefact would be preferable. During the processes of manufacture, carbon is incorporated into the iron from the fuel source. If the fuel is of a material containing contemporaneous carbon, i.e. has an ambient radiocarbon signature, e.g. charcoal, then we may reliably radiocarbon date the artefact by extracting this carbon. Care must be taken, however, to ensure that re-working has not introduced multiple sources of carbon that would give an erroneous date. Detailed chemical analysis must precede radiocarbon analysis. Sample size is determined by carbon content, and before the advent of accelerator mass spectrometry, several tens of grams of carbon were required for radiocarbon dating (van der Merwe, 1969), prohibiting this method except for high-carbon cast-irons and bulk samples, e.g. caches of nails. AMS permits the analysis of sub-gram pieces of iron (Cresswell, 1991), thereby permitting the analysis of museum pieces with only minimal loss of material, and small fragments of iron recovered from archaeological sites. A few examples are given to illustrate these points. Paper no. 41; Extended abstract. 6 refs.

Radiocarbon dating of iron artefacts

International Nuclear Information System (INIS)

Cresswell, R.

1997-01-01

Iron artefacts are generally dated by association or on stylistic grounds. This may not give a true indication of the date of manufacture, or may not be possible if the piece is out of context, ambiguous in style, or a copy. Obtaining a direct date on the artefact would be preferable. During the processes of manufacture, carbon is incorporated into the iron from the fuel source. If the fuel is of a material containing contemporaneous carbon, i.e. has an ambient radiocarbon signature, e.g. charcoal, then we may reliably radiocarbon date the artefact by extracting this carbon. Care must be taken, however, to ensure that re-working has not introduced multiple sources of carbon that would give an erroneous date. Detailed chemical analysis must precede radiocarbon analysis. Sample size is determined by carbon content, and before the advent of accelerator mass spectrometry, several tens of grams of carbon were required for radiocarbon dating (van der Merwe, 1969), prohibiting this method except for high-carbon cast-irons and bulk samples, e.g. caches of nails. AMS permits the analysis of sub-gram pieces of iron (Cresswell, 1991), thereby permitting the analysis of museum pieces with only minimal loss of material, and small fragments of iron recovered from archaeological sites. A few examples are given to illustrate these points

The effects of misinterpretation of an artefact on multidetector row CT scans in children

Energy Technology Data Exchange (ETDEWEB)

Du Plessis, Anne-Marie; Theron, Salomine; Andronikou, Savvas [University of Stellenbosch, Radiology Department, Tygerberg Hospital, Cape Town (South Africa)

2009-02-15

Artefacts reflect problems with radiographic technique rather than true pathology. These may be misinterpreted as pathology with serious consequences. An artefact caused such problems in one paediatric imaging department. To determine the incidence, and consequences of misinterpretation, of a CT artefact in a paediatric imaging department. A retrospective review of images and reports of paediatric CT scans over a set period with a known artefact was performed. Reports were correlated with reviewers' evaluation of the presence of artefact and reviewed for correct identification of artefact, misinterpretation as pathology, and action taken as a result. A total of 74 CT scans had been performed over the study period and an artefact detected by reviewers on 32 (43%). Six (18.75%) of these were misinterpreted as pathology, of which three (9.4%) were reported as tuberculous granulomas, two (6.2%) as haemorrhages and one (3.1%) as an unknown hyperdensity. Two patients (6.2%) had subsequent MRI studies performed, and treatment for tuberculosis was continued in one patient (3.1%). No initial report identified the artefact. One-fifth of the scans with the artefact were misinterpreted as pathology and half of these misinterpretations led to further action. Artefacts result in false diagnoses and unnecessary investigations; vigilance is needed. (orig.)

Partial volume and aliasing artefacts in helical cone-beam CT

International Nuclear Information System (INIS)

Zou Yu; Sidky, Emil Y; Pan, Xiaochuan

2004-01-01

A generalization of the quasi-exact algorithms of Kudo et al (2000 IEEE Trans. Med. Imaging 19 902-21) is developed that allows for data acquisition in a 'practical' frame for clinical diagnostic helical, cone-beam computed tomography (CT). The algorithm is investigated using data that model nonlinear partial volume averaging. This investigation leads to an understanding of aliasing artefacts in helical, cone-beam CT image reconstruction. An ad hoc scheme is proposed to mitigate artefacts due to the nonlinear partial volume and aliasing artefacts

The role of action knowledge in the comprehension of artefacts - a PET study

DEFF Research Database (Denmark)

Gerlach, Christian; Law, Ian; Gade, Anders

2002-01-01

and two naming tasks divided by category (natural objects vs artefacts). The left PMv (BA 6/44) was more activated by the categorization task for artefacts than by the categorization task for natural objects and the naming task for artefacts. However, the left PMv was not associated with the contrast......Activation of the left ventral premotor cortex (PMv) has in previous imaging studies been associated with the processing of visually presented artefacts. It has been suggested that this activation reflects processing of action knowledge and that action knowledge contributes to the comprehension...... of artefacts. The purpose of the present study was to test whether activation of the left PMv is common for all tasks involving the comprehension of artefacts or whether it is task specific. This was done by comparing performance and regional cerebral blood flow (rCBF) associated with two categorization tasks...

Eye-lens bismuth shielding in paediatric head CT: artefact evaluation and reduction

International Nuclear Information System (INIS)

Raissaki, Maria; Perisinakis, Kostas; Damilakis, John; Gourtsoyiannis, Nicholas

2010-01-01

CT scans of the brain, sinuses and petrous bones performed as the initial imaging test for a variety of indications have the potential to expose the eye-lens, considered among the most radiosensitive human tissues, to a radiation dose. There are several studies in adults discussing the reduction of orbital dose resulting from the use of commercially available bismuth-impregnated latex shields during CT examinations of the head. To evaluate bismuth shielding-induced artefacts and to provide suggestions for optimal eye-lens shielding in paediatric head CT. A bismuth shield was placed over the eyelids of 60 consecutive children undergoing head CT. Images were assessed for the presence and severity of artefacts with regard to eye-shield distance and shield wrinkling. An anthropomorphic paediatric phantom and thermoluminescence dosimeters (TLDs) were used to study the effect of eye lens-to-shield distance on shielding efficiency. Shields were tolerated by 56/60 children. Artefacts were absent in 45% of scans. Artefacts on orbits, not affecting and affecting orbit evaluation were noted in 39% and 14% of scans, respectively. Diagnostically insignificant artefacts on intracranial structures were noted in 1 case (2%) with shield misplacement. Mean eye-lens-to-shield distance was 8.8 mm in scans without artefacts, and 4.3 mm and 2.2 mm in scans with unimportant and diagnostically important artefacts, respectively. Artefacts occurred in 8 out of 9 cases with shield wrinkling. Dose reduction remained unchanged for different shield-to-eye distances. Bismuth shielding-related artefacts occurring in paediatric head CT are frequent, superficial and diagnostically insignificant when brain pathology is assessed. Shields should be placed 1 cm above the eyes when orbital pathology is addressed. Shield wrinkling should be avoided. (orig.)

Exploring preferences and non-use values for hidden archaeological artefacts

DEFF Research Database (Denmark)

Lundhede, Thomas; Bille, Trine; Hasler, Berit

2013-01-01

This paper presents a choice experiment study of a proposed wetland restorationproject which aims to preserve archaeological artefacts from Stone Age villages which are presently buried within the topsoil. Wetland restoration can avoid destruction of the artefacts due to agricultural cultivation...

Evaluation method of lead measurement accuracy of gears using a wedge artefact

International Nuclear Information System (INIS)

Komori, Masaharu; Takeoka, Fumi; Kubo, Aizoh; Okamoto, Kazuhiko; Osawa, Sonko; Sato, Osamu; Takatsuji, Toshiyuki

2009-01-01

The reduction of the vibration and noise of gears is an important issue in mechanical devices such as vehicles and wind turbines. The characteristics of the vibration and noise of gears are markedly affected by deviations of the tooth flank form of micrometre order; therefore, a strict quality control of the tooth flank form is required. The accuracy of the lead measurement for a gear-measuring instrument is usually evaluated using a master gear or a lead master. However, it is difficult to manufacture masters with high accuracy because the helix is a complicated geometrical form. In this paper, we propose a method of evaluating a gear-measuring instrument using a wedge artefact, which includes a highly precise plane surface. The concept of the wedge artefact is described and a mathematical model of the measuring condition of the wedge artefact is constructed. Theoretical measurement results for the wedge artefact are calculated. The wedge artefact is designed and produced on the basis of the theoretical measurement results. A measurement experiment using the wedge artefact is carried out and its effectiveness is verified

X-ray CT high-density artefact suppression in cryosurgery

International Nuclear Information System (INIS)

Wei Jikun; Sandison, George A; Chen Laigao; Liang Yun; Xu, Lisa X

2002-01-01

Advantages of x-ray CT for imaging guidance of cryosurgery include 3D visualization of frozen and unfrozen tissue and calibration of temperature in the tissue water-ice interface (0-10 deg. C) to Hounsfield units. However, use of x-ray CT images and their thermal calibration can be compromised by the cryoprobes generating high-density streak artefacts. A new subtraction technique for artefact suppression is proposed and tested in prostate cryosurgery simulations. By subtracting the measured CT x-ray projection profile without cryoprobes from the profile with cryoprobes plus iceballs, one obtains the combined profile of the cryoprobes and a low value background. Polynomial interpolation to obtain the background profile allows its addition to the original profile without probes. The result may then be fed to a conventional filtered back-projection routine to reconstruct the probe-free image. Finally the cryoprobe pixels in the originally constructed image with probes and iceballs are added back to the probe-free image to get the final artefact-suppressed image. The major advantage of this subtraction technique is that it can successfully suppress the high-density artefacts in bone-abundant body regions such as the pelvis. X-ray CT images of cryoprobe arrays in a homogeneous gelatin phantom and the pelvic region of an anthropomorphic Rando phantom containing a human skeleton were generated. After suppression, cryoprobe metal artefact streaks are reduced and visualization of the positions and dimensions of the cryoprobes are well preserved. (note)

Mapping SOA Artefacts onto an Enterprise Reference Architecture Framework

Science.gov (United States)

Noran, Ovidiu

Currently, there is still no common agreement on the service-Oriented architecture (SOA) definition, or the types and meaning of the artefacts involved in the creation and maintenance of an SOA. Furthermore, the SOA image shift from an infrastructure solution to a business-wide change project may have promoted a perception that SOA is a parallel initiative, a competitor and perhaps a successor of enterprise architecture (EA). This chapter attempts to map several typical SOA artefacts onto an enterprise reference framework commonly used in EA. This is done in order to show that the EA framework can express and structure most of the SOA artefacts and therefore, a framework for SOA could in fact be derived from an EA framework with the ensuing SOA-EA integration benefits.

PETRA, MSVAT-SPACE and SEMAC sequences for metal artefact reduction in dental MR imaging

International Nuclear Information System (INIS)

Hilgenfeld, Tim; Heil, Alexander; Bendszus, Martin; Prager, Marcel; Heiland, Sabine; Schwindling, Franz Sebastian; Rammelsberg, Peter; Nittka, Mathias; Grodzki, David

2017-01-01

Dental MRI is often impaired by artefacts due to metallic dental materials. Several sequences were developed to reduce susceptibility artefacts. Here, we evaluated a set of sequences for artefact reduction for dental MRI for the first time. Artefact volume, signal-to-noise ratio (SNR) and image quality were assessed on a 3-T MRI for pointwise encoding time reduction with radial acquisition (PETRA), multiple-slab acquisition with view angle tilting gradient, based on a sampling perfection with application-optimised contrasts using different flip angle evolution (SPACE) sequence (MSVAT-SPACE), slice-encoding for metal-artefact correction (SEMAC) and compared to a standard SPACE and a standard turbo-spin-echo (TSE) sequence. Field-of-view and acquisition times were chosen to enable in vivo application. Two implant-supported prostheses were tested (porcelain fused to metal non-precious alloy and monolithic zirconia). Smallest artefact was measured for TSE sequences with no difference between the standard TSE and the SEMAC. MSVAT-SPACE reduced artefacts about 56% compared to the standard SPACE. Effect of the PETRA was dependent on sample used. Image quality and SNR were comparable for all sequences except PETRA, which yielded poor results. There is no benefit in terms of artefact reduction for SEMAC compared to standard TSE. Usage of MSVAT-SPACE is advantageous since artefacts are reduced and higher resolution is achieved. (orig.)

PETRA, MSVAT-SPACE and SEMAC sequences for metal artefact reduction in dental MR imaging

Energy Technology Data Exchange (ETDEWEB)

Hilgenfeld, Tim; Heil, Alexander; Bendszus, Martin [Heidelberg University Hospital, Department of Neuroradiology, Heidelberg (Germany); Prager, Marcel; Heiland, Sabine [Heidelberg University Hospital, Department of Neuroradiology, Heidelberg (Germany); Heidelberg University Hospital, Section of Experimental Radiology, Heidelberg (Germany); Schwindling, Franz Sebastian; Rammelsberg, Peter [Heidelberg University Hospital, Department of Prosthodontics, Heidelberg (Germany); Nittka, Mathias; Grodzki, David [Siemens Healthcare GmbH, Erlangen (Germany)

2017-12-15

Dental MRI is often impaired by artefacts due to metallic dental materials. Several sequences were developed to reduce susceptibility artefacts. Here, we evaluated a set of sequences for artefact reduction for dental MRI for the first time. Artefact volume, signal-to-noise ratio (SNR) and image quality were assessed on a 3-T MRI for pointwise encoding time reduction with radial acquisition (PETRA), multiple-slab acquisition with view angle tilting gradient, based on a sampling perfection with application-optimised contrasts using different flip angle evolution (SPACE) sequence (MSVAT-SPACE), slice-encoding for metal-artefact correction (SEMAC) and compared to a standard SPACE and a standard turbo-spin-echo (TSE) sequence. Field-of-view and acquisition times were chosen to enable in vivo application. Two implant-supported prostheses were tested (porcelain fused to metal non-precious alloy and monolithic zirconia). Smallest artefact was measured for TSE sequences with no difference between the standard TSE and the SEMAC. MSVAT-SPACE reduced artefacts about 56% compared to the standard SPACE. Effect of the PETRA was dependent on sample used. Image quality and SNR were comparable for all sequences except PETRA, which yielded poor results. There is no benefit in terms of artefact reduction for SEMAC compared to standard TSE. Usage of MSVAT-SPACE is advantageous since artefacts are reduced and higher resolution is achieved. (orig.)

Reduction of metal artefacts in musculoskeletal imaging

International Nuclear Information System (INIS)

Sutter, Reto; Dietrich, Tobias

2016-01-01

Joint replacement and other orthopaedic implants are utilized in many patients with musculoskeletal disorders. While these operations commonly show a good clinical result, a substantial number of patients need to undergo postoperative imaging during follow-up. The presence of orthopaedic implants induces severe metal artefacts at MRI and CT. We review several basic methods and advanced techniques for reducing metal artefacts at MRI and CT in order to enable a diagnostic examination in patients with metal implants. With the use of these techniques, MRI and CT are important and reliable modalities to examine patients with joint replacement and orthopaedic implants.

Technical functions : a drawbridge between the intentional and structural nature of technical artefacts

NARCIS (Netherlands)

Vermaas, P.E.; Houkes, W.N.

2006-01-01

In this paper we present an action-theoretic account of artefact using and designing and describe our ICE-theory of function ascriptions to technical artefacts. By means of this account and theory we analyse the thesis of the dual nature of technical artefacts according to which descriptions of

Some image artefacts in non-contact mode force microscopy

International Nuclear Information System (INIS)

Dinte, B.P.; Watson, G.S.; Dobson, J.F.; Myhra, S.

1996-01-01

Full text: Non-contact mode Atomic Force Microscopy (AFM), performed in air, of two-dimensional hexagonal close-packed (2DHCP) layers of 200 nm diameter polystyrene spheres yields images containing artefacts ('ghost spheres') at layer edges and vacancy sites. The origin of these artefacts is clearly not the simple convolution of the tip and sample geometries, but must be the interaction between them. A computer program was written to simulate the experimental contours, assuming that the only force between the tip and the sample is the van der Waals (dispersion) force, and that the contours traced by the AFM tip are those of constant force derivative. The energy was calculated by integrating R -6 over the volumes of the tip and the sample, with a (constant) arbitrary scaling factor. The experimental contours were reproduced by the simulations, except for the 'ghost' artefacts. The assumption that there is only a dispersion force is thus incorrect. The experiments were performed in air, so that all surfaces were coated by a layer of adsorbed moisture. It is proposed that meniscus forces may be the origin of the artefacts

How artefacts influence our actions

NARCIS (Netherlands)

Pols, A.J.K.

2013-01-01

Artefacts can influence our actions in several ways. They can be instruments, enabling and facilitating actions, where their presence affects the number and quality of the options for action available to us. They can also influence our actions in a morally more salient way, where their presence

Imaging of fullerene-like structures in CNx thin films by electron microscopy; sample preparation artefacts due to ion-beam milling

International Nuclear Information System (INIS)

Czigany, Zs.; Neidhardt, J.; Brunell, I.F.; Hultman, L.

2003-01-01

The microstructure of CN x thin films, deposited by reactive magnetron sputtering, was investigated by transmission electron microscopy (TEM) at 200 kV in plan-view and cross-sectional samples. Imaging artefacts arise in high-resolution TEM due to overlap of nm-sized fullerene-like features for specimen thickness above 5 nm. The thinnest and apparently artefact-free areas were obtained at the fracture edges of plan-view specimens floated-off from NaCl substrates. Cross-sectional samples were prepared by ion-beam milling at low energy to minimize sample preparation artefacts. The depth of the ion-bombardment-induced surface amorphization was determined by TEM cross sections of ion-milled fullerene-like CN x surfaces. The thickness of the damaged surface layer at 5 deg. grazing incidence was 13 and 10 nm at 3 and 0.8 keV, respectively, which is approximately three times larger than that observed on Si prepared under the same conditions. The shallowest damage depth, observed for 0.25 keV, was less than 1 nm. Chemical changes due to N loss and graphitization were also observed by X-ray photoelectron spectroscopy. As a consequence of chemical effects, sputtering rates of CN x films were similar to that of Si, which enables relatively fast ion-milling procedure compared to carbon compounds. No electron beam damage of fullerene-like CN x was observed at 200 kV

ARTEFACT MOBILE DATA MODEL TO SUPPORT CULTURAL HERITAGE DATA COLLECTION AND INTERPRETATION

Directory of Open Access Journals (Sweden)

Z. S. Mohamed-Ghouse

2012-07-01

Full Text Available This paper discusses the limitation of existing data structures in mobile mapping applications to support archaeologists to manage the artefact (any object made or modified by a human culture, and later recovered by an archaeological endeavor details excavated at a cultural heritage site. Current limitations of data structure in the mobile mapping application allow archeologist to record only one artefact per test pit location. In reality, more than one artefact can be excavated from the same test pit location. A spatial data model called Artefact Mobile Data Model (AMDM was developed applying existing Relational Data Base Management System (RDBMS technique to overcome the limitation. The data model was implemented in a mobile database environment called SprintDB Pro which was in turn connected to ArcPad 7.1 mobile mapping application through Open Data Base Connectivity (ODBC. In addition, the design of a user friendly application built on top of AMDM to interpret and record the technology associated with each artefact excavated in the field is also discussed in the paper. In summary, the paper discusses the design and implementation of a data model to facilitate the collection of artefacts in the field using integrated mobile mapping and database approach.

An atlas of artefacts: a teaching tool for scintillation camera quality control

International Nuclear Information System (INIS)

Busemann Sokole, E.; Graham, L.S.; Todd-Pokropek, A.; Wegst, A.; Robilotta, C.C.

2002-01-01

Aim: Evaluating results from quality control tests and recognizing possible artefacts in clinical images requires an insight into typical and atypical images and quantitative results. Learning to recognize what is acceptable requires access to different examples, and knowledge of underlying principles of image production. An atlas of image artefacts has been assembled to assist with interpreting quality control tests and recognizing artefacts in clinical images. The project was initiated and supported by the International Atomic Energy Agency (IAEA). Methods: The artefact atlas was developed and written by the first author of this abstract, based on images and information submitted by nuclear medicine users from around the world. Each image artefact example includes an accompanying descriptive text comprising a brief description of the data acquisition, radionuclide/radiopharmaceutical, circumstances under which the image was produced; results describing the images and subsequent conclusions; comments, as appropriate, giving guidelines for trouble shooting and follow-up; and, occasional literature references. The images supplied were mostly hardcopy results on film or paper. All images were digitized into JPEG format for inclusion into a digital document. Most examples were contained on one page. The atlas was reviewed by an international group of experts. Results: A total of about 250 examples from 26 centres in 16 countries were included. The examples are grouped into 6 sections: planar, SPECT, whole body, camera/computer interface, environment/radioactivity, and display/hardcopy. The atlas includes normal results, results from poor adjustment of the camera system, poor results obtained at acceptance testing, artefacts due to system malfunction, and artefacts due to environmental situations. Some image patterns are generic, others specific to system design. Results from different camera systems, as well as new and old generation systems have been included

Computer Simulation of Multidimensional Archaeological Artefacts

Directory of Open Access Journals (Sweden)

Vera Moitinho de Almeida

2013-11-01

Full Text Available The main purpose of this ongoing research is to understand possible function(s of archaeological artefacts through Reverse Engineering processes. In addition, we intend to provide new data, as well as possible explications of the archaeological record according to what it expects about social activities and working processes, by simulating the potentialities of such actions in terms of input-output relationships. Our project focuses on the Neolithic lakeside site of La Draga (Banyoles, Catalonia. In this presentation we will begin by providing a clear overview of the major guidelines used to capture and process 3D digital data of several wooden artefacts. Then, we shall present the use of semi-automated relevant feature extractions. Finally, we intend to share preliminary computer simulation issues.

Intergranular failure of roman silver artefacts

Czech Academy of Sciences Publication Activity Database

Vaníčková, J.; Děd, J.; Bartuška, Pavel; Lejček, Pavel

567-568, - (2007), s. 213-216 ISSN 0255-5476 Institutional research plan: CEZ:AV0Z10100520 Keywords : silver embrittlement * archaeological artefacts * XRD Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.399, year: 2005

Artefact biography 2.0 : the information value of corroded archaeological bronzes

NARCIS (Netherlands)

Nienhuis, J.

2017-01-01

The different phases in the life of archaeological objects can be described by artefact biography. This dissertation defines an updated version: artefact biography 2.0, and the life phases of Early Iron Age bronze studs from Oss-Zevenbergen, the Netherlands, are elaborated. Throughout the thesis,

The radiographic image: A cultural artefact?

International Nuclear Information System (INIS)

Strudwick, Ruth M.

2014-01-01

This article looks at the role of the radiographic images produced by diagnostic radiographers. An ethnographic study of the workplace culture in one diagnostic imaging department was undertaken using participant observation for four months and semi-structured interviews with ten key informants. One of the key themes; that of the radiographic image as a cultural artefact, is explored in this article. The radiographic image is a cultural artefact which radiographers are protective of and take ownership of. Radiographers are conscious of the quality of their images and the images are an important aspect of their work. Radiographers take criticism of their images personally. The radiographic image is a record of the interaction that occurs between the radiographer and the patient. The way in which radiographic images are viewed, used and judged is an important aspect of the role of diagnostic radiographer

Modelling of polysomnographic respiratory measurements for artefact detection and signal restoration

International Nuclear Information System (INIS)

Rathnayake, S I; Abeyratne, U R; Hukins, C; Duce, B

2008-01-01

Polysomnography (PSG), which incorporates measures of sleep with measures of EEG arousal, air flow, respiratory movement and oxygenation, is universally regarded as the reference standard in diagnosing sleep-related respiratory diseases such as obstructive sleep apnoea syndrome. Over 15 channels of physiological signals are measured from a subject undergoing a typical overnight PSG session. The signals often suffer from data losses, interferences and artefacts. In a typical sleep scoring session, artefact-corrupted signal segments are visually detected and removed from further consideration. This is a highly time-consuming process, and subjective judgement is required for the job. During typical sleep scoring sessions, the target is the detection of segments of diagnostic interest, and signal restoration is not utilized for distorted segments. In this paper, we propose a novel framework for artefact detection and signal restoration based on the redundancy among respiratory flow signals. We focus on the air flow (thermistor sensors) and nasal pressure signals which are clinically significant in detecting respiratory disturbances. The method treats the respiratory system and other organs that provide respiratory-related inputs/outputs to it (e.g., cardiovascular, brain) as a possibly nonlinear coupled-dynamical system, and uses the celebrated Takens embedding theorem as the theoretical basis for signal prediction. Nonlinear prediction across time (self-prediction) and signals (cross-prediction) provides us with a mechanism to detect artefacts as unexplained deviations. In addition to detection, the proposed method carries the potential to correct certain classes of artefacts and restore the signal. In this study, we categorize commonly occurring artefacts and distortions in air flow and nasal pressure measurements into several groups and explore the efficacy of the proposed technique in detecting/recovering them. The results we obtained from a database of clinical

THE A (H1N1 INFLUENZA. SYMBOLIC DIMENSIONS OF A PANDEMIC ARTEFACT

Directory of Open Access Journals (Sweden)

Andrés G. Seguel

2013-01-01

Full Text Available The aim of the present paper is to present the symbolic features that are exposed by the concept of artefact in the context of a pandemic alarm, such as the A (H1N1 influenza. The symbolic qualities entailed by the notion of artefact are well-known within the Social Sciences: Sociology, Anthropology, Archaeology, and Linguistics. The artefact is basically not an object, but an action aimed at designing, simulating or creating a simile by means of material, technological or linguistic structures. The purpose of the present work is to unveil the symbolic dimensions that are activated by the A (H1N1 influenza as a Pandemic Artefact: a the assumption of separating information from matter; b the need for a material support to enable the exchange; c the sociological reflexivity of the artefact and its agency; d the arbitrariness of its social use, that detaches it from the design as intention.

Novel artefact removal algorithms for co-registered EEG/fMRI based on selective averaging and subtraction.

Science.gov (United States)

de Munck, Jan C; van Houdt, Petra J; Gonçalves, Sónia I; van Wegen, Erwin; Ossenblok, Pauly P W

2013-01-01

Co-registered EEG and functional MRI (EEG/fMRI) is a potential clinical tool for planning invasive EEG in patients with epilepsy. In addition, the analysis of EEG/fMRI data provides a fundamental insight into the precise physiological meaning of both fMRI and EEG data. Routine application of EEG/fMRI for localization of epileptic sources is hampered by large artefacts in the EEG, caused by switching of scanner gradients and heartbeat effects. Residuals of the ballistocardiogram (BCG) artefacts are similarly shaped as epileptic spikes, and may therefore cause false identification of spikes. In this study, new ideas and methods are presented to remove gradient artefacts and to reduce BCG artefacts of different shapes that mutually overlap in time. Gradient artefacts can be removed efficiently by subtracting an average artefact template when the EEG sampling frequency and EEG low-pass filtering are sufficient in relation to MR gradient switching (Gonçalves et al., 2007). When this is not the case, the gradient artefacts repeat themselves at time intervals that depend on the remainder between the fMRI repetition time and the closest multiple of the EEG acquisition time. These repetitions are deterministic, but difficult to predict due to the limited precision by which these timings are known. Therefore, we propose to estimate gradient artefact repetitions using a clustering algorithm, combined with selective averaging. Clustering of the gradient artefacts yields cleaner EEG for data recorded during scanning of a 3T scanner when using a sampling frequency of 2048 Hz. It even gives clean EEG when the EEG is sampled with only 256 Hz. Current BCG artefacts-reduction algorithms based on average template subtraction have the intrinsic limitation that they fail to deal properly with artefacts that overlap in time. To eliminate this constraint, the precise timings of artefact overlaps were modelled and represented in a sparse matrix. Next, the artefacts were disentangled with

Prototype metal artefact reduction algorithm in flat panel computed tomography - evaluation in patients undergoing transarterial hepatic radioembolisation.

Science.gov (United States)

Hamie, Qeumars Mustafa; Kobe, Adrian Raoul; Mietzsch, Leif; Manhart, Michael; Puippe, Gilbert Dominique; Pfammatter, Thomas; Guggenberger, Roman

2018-01-01

To investigate the effect of an on-site prototype metal artefact reduction (MAR) algorithm in cone-beam CT-catheter-arteriography (CBCT-CA) in patients undergoing transarterial radioembolisation (RE) of hepatic masses. Ethical board approved retrospective study of 29 patients (mean 63.7±13.7 years, 11 female), including 16 patients with arterial metallic coils, undergoing CBCT-CA (8s scan, 200 degrees rotation, 397 projections). Image reconstructions with and without prototype MAR algorithm were evaluated quantitatively (streak-artefact attenuation changes) and qualitatively (visibility of hepatic parenchyma and vessels) in near- (3cm) of artefact sources (metallic coils and catheters). Quantitative and qualitative measurements of uncorrected and MAR corrected images and different artefact sources were compared RESULTS: Quantitative evaluation showed significant reduction of near- and far-field streak-artefacts with MAR for both artefact sources (p0.05). Inhomogeneities of attenuation values were significantly higher for metallic coils compared to catheters (pprototype MAR algorithm improves image quality in proximity of metallic coil and catheter artefacts. • Metal objects cause artefacts in cone-beam computed tomography (CBCT) imaging. • These artefacts can be corrected by metal artefact reduction (MAR) algorithms. • Corrected images show significantly better visibility of nearby hepatic vessels and tissue. • Better visibility may facilitate image interpretation, save time and radiation exposure.

Optimization of metal artefact reduction (MAR) sequences for MRI of total hip prostheses

Energy Technology Data Exchange (ETDEWEB)

Toms, A.P., E-mail: andoni.toms@nnuh.nhs.u [Department of Radiology, Norfolk and Norwich University Hospital Trust, Norwich, Norfolk NR4 7UY (United Kingdom); Smith-Bateman, C.; Malcolm, P.N.; Cahir, J. [Department of Radiology, Norfolk and Norwich University Hospital Trust, Norwich, Norfolk NR4 7UY (United Kingdom); Graves, M. [University Department of Radiology, Addenbrooke' s Hospital, Cambridge (United Kingdom)

2010-06-15

Aim: To describe the relative contribution of matrix size and bandwidth to artefact reduction in order to define optimal sequence parameters for metal artefact reduction (MAR) sequences for MRI of total hip prostheses. Methods and materials: A phantom was created using a Charnley total hip replacement. Mid-coronal T1-weighted (echo time 12 ms, repetition time 400 ms) images through the prosthesis were acquired with increasing bandwidths (150, 300, 454, 592, and 781 Hz/pixel) and increasing matrixes of 128, 256, 384, 512, 640, and 768 pixels square. Signal loss from the prosthesis and susceptibility artefact was segmented using an automated tool. Results: Over 90% of the achievable reduction in artefacts was obtained with matrixes of 256 x 256 or greater and a receiver bandwidth of approximately 400 Hz/pixel or greater. Thereafter increasing the receiver bandwidth or matrix had little impact on reducing susceptibility artefacts. Increasing the bandwidth produced a relative fall in the signal-to-noise ratio (SNR) of between 49 and 56% for a given matrix, but, in practice, the image quality was still satisfactory even with the highest bandwidth and largest matrix sizes. The acquisition time increased linearly with increasing matrix parameters. Conclusion: Over 90% of the achievable metal artefact reduction can be realized with mid-range matrices and receiver bandwidths on a clinical 1.5 T system. The loss of SNR from increasing receiver bandwidth, is preferable to long acquisition times, and therefore, should be the main tool for reducing metal artefact.

Simultaneous EEG–fMRI: evaluating the effect of the cabling configuration on the gradient artefact

International Nuclear Information System (INIS)

Chowdhury, M E H; Mullinger, Karen J; Bowtell, Richard

2015-01-01

EEG recordings made in combined EEG–fMRI studies are corrupted by gradient artefacts (GAs) resulting from the interaction of the EEG system with the time-varying magnetic field gradients used in MRI. The dominant contribution to the GA arises from interaction with the leads of the EEG cap and the human head, but artefacts are also produced in the cables used to connect the EEG cap to the amplifier. The aim of this study is to measure the effects of the connecting cable configuration on the characteristics of the GA. We measured the GA produced on two different cable configurations (a ribbon cable and a cable consisting of wires that are twisted together to form a cylindrical bundle) by gradient pulses applied on three orthogonal axes and also characterized the effect of each cable configuration on the GA generated by a multi-slice echo planar imaging sequence, as employed in typical EEG–fMRI studies. The results demonstrate that the cabling that connects the EEG cap to the amplifier can make a significant contribution to the GA recorded during EEG–fMRI studies. In particular, we demonstrate that the GA generated by a ribbon cable is larger than that produced using a twisted cable arrangement and that changes in the GA resulting from variation in the cable position are also greater for the ribbon cable. (note)

Simultaneous EEG-fMRI: evaluating the effect of the cabling configuration on the gradient artefact

Science.gov (United States)

Chowdhury, M. E. H.; Mullinger, Karen J.; Bowtell, Richard

2015-06-01

EEG recordings made in combined EEG-fMRI studies are corrupted by gradient artefacts (GAs) resulting from the interaction of the EEG system with the time-varying magnetic field gradients used in MRI. The dominant contribution to the GA arises from interaction with the leads of the EEG cap and the human head, but artefacts are also produced in the cables used to connect the EEG cap to the amplifier. The aim of this study is to measure the effects of the connecting cable configuration on the characteristics of the GA. We measured the GA produced on two different cable configurations (a ribbon cable and a cable consisting of wires that are twisted together to form a cylindrical bundle) by gradient pulses applied on three orthogonal axes and also characterized the effect of each cable configuration on the GA generated by a multi-slice echo planar imaging sequence, as employed in typical EEG-fMRI studies. The results demonstrate that the cabling that connects the EEG cap to the amplifier can make a significant contribution to the GA recorded during EEG-fMRI studies. In particular, we demonstrate that the GA generated by a ribbon cable is larger than that produced using a twisted cable arrangement and that changes in the GA resulting from variation in the cable position are also greater for the ribbon cable.

Artefacts in geometric phase analysis of compound materials

Energy Technology Data Exchange (ETDEWEB)

Peters, Jonathan J.P., E-mail: j.j.p.peters@warwick.ac.uk [Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL (United Kingdom); Beanland, Richard; Alexe, Marin [Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL (United Kingdom); Cockburn, John W.; Revin, Dmitry G.; Zhang, Shiyong Y. [Department of Physics and Astronomy, University of Sheffield, Hounsfield Road, Sheffield S3 7RH (United Kingdom); Sanchez, Ana M., E-mail: a.m.sanchez@warwick.ac.uk [Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL (United Kingdom)

2015-10-15

The geometric phase analysis (GPA) algorithm is known as a robust and straightforward technique that can be used to measure lattice strains in high resolution transmission electron microscope (TEM) images. It is also attractive for analysis of aberration-corrected scanning TEM (ac-STEM) images that resolve every atom column, since it uses Fourier transforms and does not require real-space peak detection and assignment to appropriate sublattices. Here it is demonstrated that, in ac-STEM images of compound materials with compositionally distinct atom columns, an additional geometric phase is present in the Fourier transform. If the structure changes from one area to another in the image (e.g. across an interface), the change in this additional phase will appear as a strain in conventional GPA, even if there is no lattice strain. Strategies to avoid this pitfall are outlined. - Highlights: • GPA is shown to produce incorrect strains when applied to images of compound materials. • A mathematical description is laid out for why GPA can produce artefacts. • The artefact is demonstrated using experimental and simulated data. • A ‘rule’ is set to avoid this artefact in GPA.

Iterative metal artefact reduction (MAR) in postsurgical chest CT: comparison of three iMAR-algorithms.

Science.gov (United States)

Aissa, Joel; Boos, Johannes; Sawicki, Lino Morris; Heinzler, Niklas; Krzymyk, Karl; Sedlmair, Martin; Kröpil, Patric; Antoch, Gerald; Thomas, Christoph

2017-11-01

The purpose of this study was to evaluate the impact of three novel iterative metal artefact (iMAR) algorithms on image quality and artefact degree in chest CT of patients with a variety of thoracic metallic implants. 27 postsurgical patients with thoracic implants who underwent clinical chest CT between March and May 2015 in clinical routine were retrospectively included. Images were retrospectively reconstructed with standard weighted filtered back projection (WFBP) and with three iMAR algorithms (iMAR-Algo1 = Cardiac algorithm, iMAR-Algo2 = Pacemaker algorithm and iMAR-Algo3 = ThoracicCoils algorithm). The subjective and objective image quality was assessed. Averaged over all artefacts, artefact degree was significantly lower for the iMAR-Algo1 (58.9 ± 48.5 HU), iMAR-Algo2 (52.7 ± 46.8 HU) and the iMAR-Algo3 (51.9 ± 46.1 HU) compared with WFBP (91.6 ± 81.6 HU, p algorithms, respectively. iMAR-Algo2 and iMAR-Algo3 reconstructions decreased mild and moderate artefacts compared with WFBP and iMAR-Algo1 (p algorithms led to a significant reduction of metal artefacts and increase in overall image quality compared with WFBP in chest CT of patients with metallic implants in subjective and objective analysis. The iMARAlgo2 and iMARAlgo3 were best for mild artefacts. IMARAlgo1 was superior for severe artefacts. Advances in knowledge: Iterative MAR led to significant artefact reduction and increase image-quality compared with WFBP in CT after implementation of thoracic devices. Adjusting iMAR-algorithms to patients' metallic implants can help to improve image quality in CT.

Augmenting Everyday Artefacts to Support Social Interaction Among Senior Peers

DEFF Research Database (Denmark)

Nazzi, Elena; Sokoler, Tomas

2015-01-01

Novel technological possibilities emerge when tangible and social computing come together. This paper explores the potential of such technology when designing for seniors and their social interaction. Our research is guided by the concept of twitterIDo, which is to make seniors’ everyday activities...... and displays designed to start a dialogue with the seniors on how twitterIDo-technology may fit into their everyday situations. Our findings point out how augmented everyday artefacts can make a positive difference when designing technology in a domain such the one of seniors’ and their social interaction...... more visible by augmenting everyday artefacts to communicate the ongoing activity they are used for. We engaged a local community of seniors in a living lab to explore the possibilities of twitterIDo in real life situations. This paper presents a series of interactive prototypes of everyday artefacts...

Electrically evoked compound action potentials artefact rejection by independent component analysis: procedure automation.

Science.gov (United States)

Akhoun, Idrick; McKay, Colette; El-Deredy, Wael

2015-01-15

Independent-components-analysis (ICA) successfully separated electrically-evoked compound action potentials (ECAPs) from the stimulation artefact and noise (ECAP-ICA, Akhoun et al., 2013). This paper shows how to automate the ECAP-ICA artefact cancellation process. Raw-ECAPs without artefact rejection were consecutively recorded for each stimulation condition from at least 8 intra-cochlear electrodes. Firstly, amplifier-saturated recordings were discarded, and the data from different stimulus conditions (different current-levels) were concatenated temporally. The key aspect of the automation procedure was the sequential deductive source categorisation after ICA was applied with a restriction to 4 sources. The stereotypical aspect of the 4 sources enables their automatic classification as two artefact components, a noise and the sought ECAP based on theoretical and empirical considerations. The automatic procedure was tested using 8 cochlear implant (CI) users and one to four stimulus electrodes. The artefact and noise sources were successively identified and discarded, leaving the ECAP as the remaining source. The automated ECAP-ICA procedure successfully extracted the correct ECAPs compared to standard clinical forward masking paradigm in 22 out of 26 cases. ECAP-ICA does not require extracting the ECAP from a combination of distinct buffers as it is the case with regular methods. It is an alternative that does not have the possible bias of traditional artefact rejections such as alternate-polarity or forward-masking paradigms. The ECAP-ICA procedure bears clinical relevance, for example as the artefact rejection sub-module of automated ECAP-threshold detection techniques, which are common features of CI clinical fitting software. Copyright © 2014. Published by Elsevier B.V.

Fitts' law as a design artefact

DEFF Research Database (Denmark)

Bertelsen, Olav Wedege

1994-01-01

Fitts' law is described and discussed as an example of use of theory in human-computer interaction design. The dichotomy between academic theory and applied theory is rejected and replaced by a radical pragmatic notion of theories as design artefacts. Different roles of theory in design...

Reduction of dental metallic artefacts in CT: Value of a newly developed algorithm for metal artefact reduction (O-MAR)

International Nuclear Information System (INIS)

Kidoh, M.; Nakaura, T.; Nakamura, S.; Tokuyasu, S.; Osakabe, H.; Harada, K.; Yamashita, Y.

2014-01-01

Aim: To evaluate the image quality of O-MAR (Metal Artifact Reduction for Orthopedic Implants) for dental metal artefact reduction. Materials and methods: This prospective study received institutional review board approval and written informed consent was obtained. Thirty patients who had dental implants or dental fillings were included in this study. Computed tomography (CT) images were obtained through the oral cavity and neck during the portal venous phase. The system reconstructed the O-MAR-processed images in addition to the uncorrected images. CT attenuation and image noise of the soft tissue of the oral cavity were compared between the O-MAR and the uncorrected images. Qualitative analysis was undertaken between the two image groups. Results: The image noise of the O-MAR images was significantly lower than that of the uncorrected images (p < 0.01). O-MAR offered plausible attenuations of soft tissue compared with non-O-MAR. Better qualitative scores were obtained in the streaking artefacts and the degree of depiction of the oral cavity with O-MAR compared with non-O-MAR. Conclusion: O-MAR enables the depiction of structures in areas in which this was not previously possible due to dental metallic artefacts in qualitative image analysis. O-MAR images may have a supplementary role in addition to uncorrected images in oral diagnosis

EXPLOITING MIRRORS IN 3D RECONSTRUCTION OF SMALL ARTEFACTS

Directory of Open Access Journals (Sweden)

G. Kontogianni

2018-05-01

Full Text Available 3D reconstruction of small artefacts is very significant in order to capture the details of the whole object irrespective of the documentation method which is used (Ranged Based or Image Based. Sometimes it is very difficult to achieve it because of hidden parts, occlusions, and obstructions which the object has. Hence, more data are necessary in order to 3D digitise the whole of the artefact leading to increased time for collecting and consequently processing the data. A methodology is necessary in order to reduce the collection of the data and therefore their processing time especially in cases of mass digitisation. So in this paper, the use of mirrors in particular high-quality mirrors in the data acquisition phase for the 3D reconstruction of small artefacts is investigated. Two case studies of 3D reconstruction are presented: the first one concerns Range-Based modelling especially a Time of Flight laser scanner is utilised and in the second one Image-Based modelling technique is implemented.

Image recovery by removing stochastic artefacts identified as local asymmetries

International Nuclear Information System (INIS)

Osterloh, K; Zscherpel, U; Ewert, U; Bücherl, T

2012-01-01

Stochastic artefacts are frequently encountered in digital radiography and tomography with neutrons. Most obviously, they are caused by ubiquitous scattered radiation hitting the CCD-sensor. They appear as scattered dots and, at higher frequency of occurrence, they may obscure the image. Some of these dotted interferences vary with time, however, a large portion of them remains persistent so the problem cannot be resolved by collecting stacks of images and to merge them to a median image. The situation becomes even worse in computed tomography (CT) where each artefact causes a circular pattern in the reconstructed plane. Therefore, these stochastic artefacts have to be removed completely and automatically while leaving the original image content untouched. A simplified image acquisition and artefact removal tool was developed at BAM and is available to interested users. Furthermore, an algorithm complying with all the requirements mentioned above was developed that reliably removes artefacts that could even exceed the size of a single pixel without affecting other parts of the image. It consists of an iterative two-step algorithm adjusting pixel values within a 3 × 3 matrix inside of a 5 × 5 kernel and the centre pixel only within a 3 × 3 kernel, resp. It has been applied to thousands of images obtained from the NECTAR facility at the FRM II in Garching, Germany, without any need of a visual control. In essence, the procedure consists of identifying and tackling asymmetric intensity distributions locally with recording each treatment of a pixel. Searching for the local asymmetry with subsequent correction rather than replacing individually identified pixels constitutes the basic idea of the algorithm. The efficiency of the proposed algorithm is demonstrated with a severely spoiled example of neutron radiography and tomography as compared with median filtering, the most convenient alternative approach by visual check, histogram and power spectra analysis.

A short overview of MRI artefacts

African Journals Online (AJOL)

Enrique

sampling in the phase-encoding direction is the significant difference in the time of acquisition in the fre- ... Department of Medical Physics. University of the Free State. Bloemfontein. Fig. 1. Motion artefact (T1 ..... to image expansion for improved definition. IEEE Trans Med Imaging 1994; 3:233-242. 13. Holden M, Breeuwer ...

Removing Ocular Movement Artefacts by a Joint Smoothened Subspace Estimator

Directory of Open Access Journals (Sweden)

Ronald Phlypo

2007-01-01

Full Text Available To cope with the severe masking of background cerebral activity in the electroencephalogram (EEG by ocular movement artefacts, we present a method which combines lower-order, short-term and higher-order, long-term statistics. The joint smoothened subspace estimator (JSSE calculates the joint information in both statistical models, subject to the constraint that the resulting estimated source should be sufficiently smooth in the time domain (i.e., has a large autocorrelation or self predictive power. It is shown that the JSSE is able to estimate a component from simulated data that is superior with respect to methodological artefact suppression to those of FastICA, SOBI, pSVD, or JADE/COM1 algorithms used for blind source separation (BSS. Interference and distortion suppression are of comparable order when compared with the above-mentioned methods. Results on patient data demonstrate that the method is able to suppress blinking and saccade artefacts in a fully automated way.

The Role of Artefacts in Presence Mediation

NARCIS (Netherlands)

Vyas, Dhaval; Tzovaras, D

2007-01-01

Approaches to support computer mediated communication (CMC) have predominantly relied on the face-to-face communication paradigm. However, interaction and coordination can also be supported by different technological artefacts. In fact, most researches [1, 2, 3] related to ethnomethodology have

Ring down artefacts on abdominal sonography to predict pulmonary abnormalities in the emergency department.

Science.gov (United States)

Tsai, C-L; Wang, H-P; Lien, W-C; Chen, C-C; Lai, T-I; Chen, W-J

2005-10-01

Ring down artefacts are sometimes found when emergency physicians perform abdominal ultrasound to differentiate between various abdominal problems. We describe a patient who presented with right upper quadrant abdominal pain and whose ultrasound examination showed ring down artefacts posterior to the right hemidiaphragm, which led to the eventual diagnosis of pneumonia. Ring down artefacts on ultrasound may be used to predict pulmonary abnormalities. Awareness of this sonographic finding may assist in accurate diagnosis and administration of appropriate treatment without delay.

Head and neck imaging with PET and PET/CT: artefacts from dental metallic implants

International Nuclear Information System (INIS)

Goerres, Gerhard W.; Hany, Thomas F.; Kamel, Ehab; Schulthess von, Gustav K.; Buck, Alfred

2002-01-01

Germanium-68 based attenuation correction (PET Ge68 ) is performed in positron emission tomography (PET) imaging for quantitative measurements. With the recent introduction of combined in-line PET/CT scanners, CT data can be used for attenuation correction. Since dental implants can cause artefacts in CT images, CT-based attenuation correction (PET CT ) may induce artefacts in PET images. The purpose of this study was to evaluate the influence of dental metallic artwork on the quality of PET images by comparing non-corrected images and images attenuation corrected by PET Ge68 and PET CT . Imaging was performed on a novel in-line PET/CT system using a 40-mAs scan for PET CT in 41 consecutive patients with high suspicion of malignant or inflammatory disease. In 17 patients, additional PET Ge68 images were acquired in the same imaging session. Visual analysis of fluorine-18 fluorodeoxyglucose (FDG) distribution in several regions of the head and neck was scored on a 4-point scale in comparison with normal grey matter of the brain in the corresponding PET images. In addition, artefacts adjacent to dental metallic artwork were evaluated. A significant difference in image quality scoring was found only for the lips and the tip of the nose, which appeared darker on non-corrected than on corrected PET images. In 33 patients, artefacts were seen on CT, and in 28 of these patients, artefacts were also seen on PET imaging. In eight patients without implants, artefacts were seen neither on CT nor on PET images. Direct comparison of PET Ge68 and PET CT images showed a different appearance of artefacts in 3 of 17 patients. Malignant lesions were equally well visible using both transmission correction methods. Dental implants, non-removable bridgework etc. can cause artefacts in attenuation-corrected images using either a conventional 68 Ge transmission source or the CT scan obtained with a combined PET/CT camera. We recommend that the non-attenuation-corrected PET images also be

Dosimetric impact of a CT metal artefact suppression algorithm for proton, electron and photon therapies

International Nuclear Information System (INIS)

Wei Jikun; Sandison, George A; Hsi, W-C; Ringor, Michael; Lu Xiaoyi

2006-01-01

Accurate dose calculation is essential to precision radiation treatment planning and this accuracy depends upon anatomic and tissue electron density information. Modern treatment planning inhomogeneity corrections use x-ray CT images and calibrated scales of tissue CT number to electron density to provide this information. The presence of metal in the volume scanned by an x-ray CT scanner causes metal induced image artefacts that influence CT numbers and thereby introduce errors in the radiation dose distribution calculated. This paper investigates the dosimetric improvement achieved by a previously proposed x-ray CT metal artefact suppression technique when the suppressed images of a patient with bilateral hip prostheses are used in commercial treatment planning systems for proton, electron or photon therapies. For all these beam types, this clinical image and treatment planning study reveals that the target may be severely underdosed if a metal artefact-contaminated image is used for dose calculations instead of the artefact suppressed one. Of the three beam types studied, the metal artefact suppression is most important for proton therapy dose calculations, intermediate for electron therapy and least important for x-ray therapy but still significant. The study of a water phantom having a metal rod simulating a hip prosthesis indicates that CT numbers generated after image processing for metal artefact suppression are accurate and thus dose calculations based on the metal artefact suppressed images will be of high fidelity

A framework to evaluate the educational potential of a digital artefact for math learning

Directory of Open Access Journals (Sweden)

Chiappini Giampaolo

2015-12-01

Full Text Available This article provides a methodology with two potential applications: to prove useful to maths teachers for analysing and evaluating the educational potential of different digital artefacts and to help designers of maths learning artefacts to evaluate their design during the implementation phase. The educational potential of an artefact is considered as an entity determined by actions and representations structure available within the artefact, the interpretation and behaviour of who uses it and the features of the activity in which it is used. The proposed methodology is based on the notions of affordance, narrative and cycle of expansive learning. The methodology has been applied on AlNuSet, a system designed for supporting the teaching and learning of algebra by means of modalities of interaction that are of visual, spatial and motor nature.

ASPECTS OF BIODETERIORATION OF LAPIDEOUS SUBMERGED ARTEFACTS: 3D METHODOLOGIES APPLICATION

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S. Ricci

2015-04-01

Full Text Available Submerged stone archaeological artefacts are bioeroded by endolithic microbiota (cyanobacteria, algae and fungi and macroborers (Porifera, Bivalvia and Sipuncula. Optical microscope and SEM observations permit to analyse the bioerosion traces and to identify bioeroders. Data obtained with these techniques cannot be used to estimate volumes of material bioeroded. This aspect require the need to collect three-dimensional, close-range data from artefact. In this work we illustrate two 3D imaging techniques used to study bioerosion phenomena of underwater Cultural Heritage. In particular Digital Video Microscope permit the elaboration of 3D images, which are widely employed for close-range acquisitions. Underwater Laser Scanner documents the in situ degradation of submerged artefacts. This research aims to sensitize specialist figures in the study 3D offering a starting point for future collaborations that could lead to interesting results.

Prototype metal artefact reduction algorithm in flat panel computed tomography - evaluation in patients undergoing transarterial hepatic radioembolisation

International Nuclear Information System (INIS)

Hamie, Qeumars Mustafa; Kobe, Adrian Raoul; Mietzsch, Leif; Puippe, Gilbert Dominique; Pfammatter, Thomas; Guggenberger, Roman; Manhart, Michael

2018-01-01

To investigate the effect of an on-site prototype metal artefact reduction (MAR) algorithm in cone-beam CT-catheter-arteriography (CBCT-CA) in patients undergoing transarterial radioembolisation (RE) of hepatic masses. Ethical board approved retrospective study of 29 patients (mean 63.7±13.7 years, 11 female), including 16 patients with arterial metallic coils, undergoing CBCT-CA (8s scan, 200 degrees rotation, 397 projections). Image reconstructions with and without prototype MAR algorithm were evaluated quantitatively (streak-artefact attenuation changes) and qualitatively (visibility of hepatic parenchyma and vessels) in near- (<1cm) and far-field (>3cm) of artefact sources (metallic coils and catheters). Quantitative and qualitative measurements of uncorrected and MAR corrected images and different artefact sources were compared Quantitative evaluation showed significant reduction of near- and far-field streak-artefacts with MAR for both artefact sources (p<0.001), while remaining stable for unaffected organs (all p>0.05). Inhomogeneities of attenuation values were significantly higher for metallic coils compared to catheters (p<0.001) and decreased significantly for both after MAR (p<0.001). Qualitative image scores were significantly improved after MAR (all p<0.003) with by trend higher artefact degrees for metallic coils compared to catheters. In patients undergoing CBCT-CA for transarterial RE, prototype MAR algorithm improves image quality in proximity of metallic coil and catheter artefacts. (orig.)

Prototype metal artefact reduction algorithm in flat panel computed tomography - evaluation in patients undergoing transarterial hepatic radioembolisation

Energy Technology Data Exchange (ETDEWEB)

Hamie, Qeumars Mustafa; Kobe, Adrian Raoul; Mietzsch, Leif; Puippe, Gilbert Dominique; Pfammatter, Thomas; Guggenberger, Roman [University Hospital Zurich, Department of Radiology, Zurich (Switzerland); Manhart, Michael [Imaging Concepts, HC AT IN IMC, Siemens Healthcare GmbH, Advanced Therapies, Innovation, Forchheim (Germany)

2018-01-15

To investigate the effect of an on-site prototype metal artefact reduction (MAR) algorithm in cone-beam CT-catheter-arteriography (CBCT-CA) in patients undergoing transarterial radioembolisation (RE) of hepatic masses. Ethical board approved retrospective study of 29 patients (mean 63.7±13.7 years, 11 female), including 16 patients with arterial metallic coils, undergoing CBCT-CA (8s scan, 200 degrees rotation, 397 projections). Image reconstructions with and without prototype MAR algorithm were evaluated quantitatively (streak-artefact attenuation changes) and qualitatively (visibility of hepatic parenchyma and vessels) in near- (<1cm) and far-field (>3cm) of artefact sources (metallic coils and catheters). Quantitative and qualitative measurements of uncorrected and MAR corrected images and different artefact sources were compared Quantitative evaluation showed significant reduction of near- and far-field streak-artefacts with MAR for both artefact sources (p<0.001), while remaining stable for unaffected organs (all p>0.05). Inhomogeneities of attenuation values were significantly higher for metallic coils compared to catheters (p<0.001) and decreased significantly for both after MAR (p<0.001). Qualitative image scores were significantly improved after MAR (all p<0.003) with by trend higher artefact degrees for metallic coils compared to catheters. In patients undergoing CBCT-CA for transarterial RE, prototype MAR algorithm improves image quality in proximity of metallic coil and catheter artefacts. (orig.)

A knowledge-based method for reducing attenuation artefacts caused by cardiac appliances in myocardial PET/CT

International Nuclear Information System (INIS)

Hamill, James J; Brunken, Richard C; Bybel, Bohdan; DiFilippo, Frank P; Faul, David D

2006-01-01

Attenuation artefacts due to implanted cardiac defibrillator leads have previously been shown to adversely impact cardiac PET/CT imaging. In this study, the severity of the problem is characterized, and an image-based method is described which reduces the resulting artefact in PET. Automatic implantable cardioverter defibrillator (AICD) leads cause a moving-metal artefact in the CT sections from which the PET attenuation correction factors (ACFs) are derived. Fluoroscopic cine images were measured to demonstrate that the defibrillator's highly attenuating distal shocking coil moves rhythmically across distances on the order of 1 cm. Rhythmic motion of this magnitude was created in a phantom with a moving defibrillator lead. A CT study of the phantom showed that the artefact contained regions of incorrect, very high CT values and adjacent regions of incorrect, very low CT values. The study also showed that motion made the artefact more severe. A knowledge-based metal artefact reduction method (MAR) is described that reduces the magnitude of the error in the CT images, without use of the corrupted sinograms. The method modifies the corrupted image through a sequence of artefact detection procedures, morphological operations, adjustments of CT values and three-dimensional filtering. The method treats bone the same as metal. The artefact reduction method is shown to run in a few seconds, and is validated by applying it to a series of phantom studies in which reconstructed PET tracer distribution values are wrong by as much as 60% in regions near the CT artefact when MAR is not applied, but the errors are reduced to about 10% of expected values when MAR is applied. MAR changes PET image values by a few per cent in regions not close to the artefact. The changes can be larger in the vicinity of bone. In patient studies, the PET reconstruction without MAR sometimes results in anomalously high values in the infero-septal wall. Clinical performance of MAR is assessed by two

METHODOLOGY TO CREATE DIGITAL AND VIRTUAL 3D ARTEFACTS IN ARCHAEOLOGY

Directory of Open Access Journals (Sweden)

Calin Neamtu

2016-12-01

Full Text Available The paper presents a methodology to create 3D digital and virtual artefacts in the field of archaeology using CAD software solution. The methodology includes the following steps: the digitalization process, the digital restoration and the dissemination process within a virtual environment. The resulted 3D digital artefacts have to be created in files formats that are compatible with a large variety of operating systems and hardware configurations such as: computers, graphic tablets and smartphones. The compatibility and portability of these 3D file formats has led to a series of quality related compromises to the 3D models in order to integrate them on in a wide variety of application that are running on different hardware configurations. The paper illustrates multiple virtual reality and augmented reality application that make use of the virtual 3D artefacts that have been generated using this methodology.

Statistical iterative reconstruction for streak artefact reduction when using multidetector CT to image the dento-alveolar structures.

Science.gov (United States)

Dong, J; Hayakawa, Y; Kober, C

2014-01-01

When metallic prosthetic appliances and dental fillings exist in the oral cavity, the appearance of metal-induced streak artefacts is not avoidable in CT images. The aim of this study was to develop a method for artefact reduction using the statistical reconstruction on multidetector row CT images. Adjacent CT images often depict similar anatomical structures. Therefore, reconstructed images with weak artefacts were attempted using projection data of an artefact-free image in a neighbouring thin slice. Images with moderate and strong artefacts were continuously processed in sequence by successive iterative restoration where the projection data was generated from the adjacent reconstructed slice. First, the basic maximum likelihood-expectation maximization algorithm was applied. Next, the ordered subset-expectation maximization algorithm was examined. Alternatively, a small region of interest setting was designated. Finally, the general purpose graphic processing unit machine was applied in both situations. The algorithms reduced the metal-induced streak artefacts on multidetector row CT images when the sequential processing method was applied. The ordered subset-expectation maximization and small region of interest reduced the processing duration without apparent detriments. A general-purpose graphic processing unit realized the high performance. A statistical reconstruction method was applied for the streak artefact reduction. The alternative algorithms applied were effective. Both software and hardware tools, such as ordered subset-expectation maximization, small region of interest and general-purpose graphic processing unit achieved fast artefact correction.

Minimizing EIT image artefacts from mesh variability in finite element models.

Science.gov (United States)

Adler, Andy; Lionheart, William R B

2011-07-01

Electrical impedance tomography (EIT) solves an inverse problem to estimate the conductivity distribution within a body from electrical simulation and measurements at the body surface, where the inverse problem is based on a solution of Laplace's equation in the body. Most commonly, a finite element model (FEM) is used, largely because of its ability to describe irregular body shapes. In this paper, we show that simulated variations in the positions of internal nodes within a FEM can result in serious image artefacts in the reconstructed images. Such variations occur when designing FEM meshes to conform to conductivity targets, but the effects may also be seen in other applications of absolute and difference EIT. We explore the hypothesis that these artefacts result from changes in the projection of the anisotropic conductivity tensor onto the FEM system matrix, which introduces anisotropic components into the simulated voltages, which cannot be reconstructed onto an isotropic image, and appear as artefacts. The magnitude of the anisotropic effect is analysed for a small regular FEM, and shown to be proportional to the relative node movement as a fraction of element size. In order to address this problem, we show that it is possible to incorporate a FEM node movement component into the formulation of the inverse problem. These results suggest that it is important to consider artefacts due to FEM mesh geometry in EIT image reconstruction.

Assessing ECG signal quality indices to discriminate ECGs with artefacts from pathologically different arrhythmic ECGs.

Science.gov (United States)

Daluwatte, C; Johannesen, L; Galeotti, L; Vicente, J; Strauss, D G; Scully, C G

2016-08-01

False and non-actionable alarms in critical care can be reduced by developing algorithms which assess the trueness of an arrhythmia alarm from a bedside monitor. Computational approaches that automatically identify artefacts in ECG signals are an important branch of physiological signal processing which tries to address this issue. Signal quality indices (SQIs) derived considering differences between artefacts which occur in ECG signals and normal QRS morphology have the potential to discriminate pathologically different arrhythmic ECG segments as artefacts. Using ECG signals from the PhysioNet/Computing in Cardiology Challenge 2015 training set, we studied previously reported ECG SQIs in the scientific literature to differentiate ECG segments with artefacts from arrhythmic ECG segments. We found that the ability of SQIs to discriminate between ECG artefacts and arrhythmic ECG varies based on arrhythmia type since the pathology of each arrhythmic ECG waveform is different. Therefore, to reduce the risk of SQIs classifying arrhythmic events as noise it is important to validate and test SQIs with databases that include arrhythmias. Arrhythmia specific SQIs may also minimize the risk of misclassifying arrhythmic events as noise.

Comparison of methods for suppressing edge and aliasing artefacts in iterative x-ray CT reconstruction

International Nuclear Information System (INIS)

Zbijewski, Wojciech; Beekman, Freek J

2006-01-01

X-ray CT images obtained with iterative reconstruction (IR) can be hampered by the so-called edge and aliasing artefacts, which appear as interference patterns and severe overshoots in the areas of sharp intensity transitions. Previously, we have demonstrated that these artefacts are caused by discretization errors during the projection simulation step in IR. Although these errors are inherent to IR, they can be adequately suppressed by reconstruction on an image grid that is finer than that typically used for analytical methods such as filtered back-projection. Two other methods that may prevent edge artefacts are: (i) smoothing the projections prior to reconstruction or (ii) using an image representation different from voxels; spherically symmetric Kaiser-Bessel functions are a frequently employed example of such a representation. In this paper, we compare reconstruction on a fine grid with the two above-mentioned alternative strategies for edge artefact reduction. We show that the use of a fine grid results in a more adequate suppression of artefacts than the smoothing of projections or using the Kaiser-Bessel image representation

A Philosophical Framework for Enhancing the Understanding of Artefacts in the Technology Classroom

Science.gov (United States)

Rauscher, Willem

2016-01-01

Technology teachers should have a sound understanding and knowledge of artefacts in order to assist learners in the designing, making and evaluating of artefacts. Unfortunately, technology teachers in South African schools seem to have a poor grasp of the complexity of this important part of knowledge that is specific to technology. As a result,…

A knowledge-based method for reducing attenuation artefacts caused by cardiac appliances in myocardial PET/CT

Energy Technology Data Exchange (ETDEWEB)

Hamill, James J [Siemens Medical Solutions, Molecular Imaging, 810 Innovation Dr., Knoxville, TN (United States); Brunken, Richard C [Department of Molecular and Functional Imaging, Cleveland Clinic Foundation, 9500 Euclid Ave., Cleveland, OH (United States); Bybel, Bohdan [Department of Molecular and Functional Imaging, Cleveland Clinic Foundation, 9500 Euclid Ave., Cleveland, OH (United States); DiFilippo, Frank P [Department of Molecular and Functional Imaging, Cleveland Clinic Foundation, 9500 Euclid Ave., Cleveland, OH (United States); Faul, David D [Siemens Medical Solutions, Molecular Imaging, 810 Innovation Dr., Knoxville, TN (United States)

2006-06-07

Attenuation artefacts due to implanted cardiac defibrillator leads have previously been shown to adversely impact cardiac PET/CT imaging. In this study, the severity of the problem is characterized, and an image-based method is described which reduces the resulting artefact in PET. Automatic implantable cardioverter defibrillator (AICD) leads cause a moving-metal artefact in the CT sections from which the PET attenuation correction factors (ACFs) are derived. Fluoroscopic cine images were measured to demonstrate that the defibrillator's highly attenuating distal shocking coil moves rhythmically across distances on the order of 1 cm. Rhythmic motion of this magnitude was created in a phantom with a moving defibrillator lead. A CT study of the phantom showed that the artefact contained regions of incorrect, very high CT values and adjacent regions of incorrect, very low CT values. The study also showed that motion made the artefact more severe. A knowledge-based metal artefact reduction method (MAR) is described that reduces the magnitude of the error in the CT images, without use of the corrupted sinograms. The method modifies the corrupted image through a sequence of artefact detection procedures, morphological operations, adjustments of CT values and three-dimensional filtering. The method treats bone the same as metal. The artefact reduction method is shown to run in a few seconds, and is validated by applying it to a series of phantom studies in which reconstructed PET tracer distribution values are wrong by as much as 60% in regions near the CT artefact when MAR is not applied, but the errors are reduced to about 10% of expected values when MAR is applied. MAR changes PET image values by a few per cent in regions not close to the artefact. The changes can be larger in the vicinity of bone. In patient studies, the PET reconstruction without MAR sometimes results in anomalously high values in the infero-septal wall. Clinical performance of MAR is assessed by

Matter(s) of interest: artefacts, spacing and timing

NARCIS (Netherlands)

Schwanen, T.

2007-01-01

This paper argues that time-geography can make a contribution to contemporary 'rematerialized' geographies, because the interconnections among social processes, human corporeality and inanimate material artefacts within the landscape were among Hägerstrand's central concerns. Time-geography needs

Designing the e-Participation Artefact

DEFF Research Database (Denmark)

Sanford, Clive Carlton; Rose, Jeremy

2008-01-01

When e-participation is considered in the context of applied research, researchers support government institutions by enabling technology for citizens who participate in policy-making. Governments' e-participation agendas involve a variety of different design activities; for example, designing new...... administrative procedures, computer literacy programs, or creating new laws. Design science aids the creation and evaluation of artefacts that are intended to find solutions to identified problems in a rigorous way. We therefore characterise three different types of e-participation design activities...

Computer Simulation of Multidimensional Archaeological Artefacts

Directory of Open Access Journals (Sweden)

Vera Moitinho de Almeida

2012-11-01

Our project focuses on the Neolithic lakeside site of La Draga (Banyoles, Catalonia. In this presentation we will begin by providing a clear overview of the major guidelines used to capture and process 3D digital data of several wooden artefacts. Then, we shall present the use of semi-automated relevant feature extractions. Finally, we intend to share preliminary computer simulation issues.

Preliminary Results of Ocular Artefacts Identification in EEC Series by Neural Network

Directory of Open Access Journals (Sweden)

M. Kofronova

1996-06-01

Full Text Available The human electroencephalogram (EEG, is record of the electrical activity of the brain and contains useful diagnostic information on a variety of neurological disorders. Normal EEG signal are usually registered from electrodes placed on the scalp, and are often very small in amplitude, of 20 µV. The EEG, like all biomedical signals, is very susceptible to a variety of large signal contamination or artefacts (signals of other than brain activity which reduce its clinical usefulness. For example, blinking or moving eyes produces large electrical potentials around the eyes called the electrooculogram (EOG. The EOG spreads across the scalp to contaminate the EEG, when it is referred to as an ocular artefact (OA. This paper includes method of identification portion of the EEG record where ocular artefact appears and classification its type by neural network.

ECG movement artefacts can be greatly reduced with the aid of a movement absorbing device

DEFF Research Database (Denmark)

Harrison, Adrian Paul; Wandall, Kirsten; Thorball, Jørgen

2007-01-01

Accurate ECG signal analysis can be confounded by electric lead, and/or electrode movements varying in origin from, for example, hiccups, tremor or patient restlessness. ECG signals recorded using either a conventional electrode holder or with the aid of an electrode holder capable of absorbing...... movement artefacts, were measured on a healthy human subject. Results show a greatly improved stability of the ECG signal recorded using an electrode holder capable of absorbing movement artefacts during periods of lead disturbance, and highlight the movement artefacts that develop when the recording lead...... of a conventional ECG electrode holder is tugged or pulled during theperiod of monitoring. It is concluded that the new design of ECG electrode holder will not only enable clearer signal recordings for clinical assessment, but will reduce the ECG artefacts associated with the transportation of patients, and may...

Problem Solving of Low Data Throughput on Mobile Devices by Artefacts Prebuffering

Directory of Open Access Journals (Sweden)

Krejcar Ondrej

2009-01-01

Full Text Available The paper deals with a problem of low data throughput on wirelessly connected mobile devices and a possibility to solve this problem by prebuffering of selected artefacts. The basics are in determining the problem parts of a mobile device and solve the problem by a model of data prebuffering-based system enhancement for locating and tracking users inside the buildings. The framework uses a WiFi network infrastructure to allow the mobile device determine its indoor position. User location is used for data prebuffering and for pushing information from a server to PDAs. All server data are saved as artefacts with its indoor position information. Accessing prebuffered data on a mobile device can significantly improve a response time needed to view large multimedia data. The solution was tested on a facility management information system built on purpose with a testing collection of about hundred large size artefacts.

Superiority of triple-detector single-photon emission tomography over single- and dual-detector systems in the minimization of motion artefacts

International Nuclear Information System (INIS)

Nakajima, Kenichi; Taki, Junichi; Michigishi, Takatoshi; Tonami, Norihisa

1998-01-01

A patient motion-related artefact is one of the most important artefacts in single-photon emission tomography (SPET) imaging. This study evaluated the effect of the number and configuration of SPET detectors on motion artefacts. The following acquisition conditions were simulated based on original 360 projection images: (1) single-detector 180 rotation (S180), (2) a dual-detector rectangular (L-shaped) 180 acquisition (D180L), (3) dual-detector cameras mounted opposite each other with 360 acquisition (D360) and (4) triple-detector 360 acquisition (T360). The motion artefacts were introduced using a syringe and a myocardial phantom. Clinical cases with technetium-99m methoxyisobutylisonitrile and thallium-201 studies were analysed to confirm the validity of this phantom simulation. The effect of continuous alternate rotation acquisition and summing the projections on the reduction of motion artefacts was investigated in each model. The effect of motion depended on the number and the configuration of the SPET detectors. A 1-pixel (6.4 mm) motion in the S180, D180L and D360 models generated only slight artefacts, and a 2-pixel motion led to an apparent decrease in activity or created hot areas in the myocardium. On the other hand, a T360 rotation created few artefacts even with a 2-pixel motion of the last quarter of the projections. Despite the difference in attenuation with 201 Tl and 99m Tc, similar artefact patterns were observed with both radionuclides in selected patient model studies. Continuous alternate rotation could reduce artefacts caused by less than a 2-pixel motion. In conclusion, calculating the average of the sum of the projections of triple-detector 360 rotations with alternate rotation is the best method to minimize motion artefacts. This ''averaging'' effect of motion artefacts is a key to this simulation. (orig.)

MRI with intraoral orthodontic appliance-a comparative in vitro and in vivo study of image artefacts at 1.5 T.

Science.gov (United States)

Zachriat, C; Asbach, P; Blankenstein, K I; Peroz, I; Blankenstein, F H

2015-01-01

We investigated artefacts caused from orthodontic appliances at 1.5-T MRI of the head and neck region and whether the image quality can be improved utilizing the artefact-minimizing sequence WARP. In vitro tests were performed by phantom measurements of different orthodontic devices applying different types of MR sequences [echoplanar imaging (EPI), turbo spin echo (TSE) and TSE-WARP, gradient echo (GRE)]. Two independent readers determined after calibration the level of artefacts. Subsequently, the interobserver agreement was calculated. The measurement of artefacts was based on the American Society for Testing Materials Standard F 2119-07. For in vivo imaging, one test person was scanned with an inserted multibracket appliance. The level of artefacts for 27 target regions was evaluated. In vitro: ceramic brackets and ferromagnetic steel brackets produced artefact radii up to 1.12 and 7.40 cm, respectively. WARP reduced these artefacts by an average of 32.7%. The Bland-Altman-Plot indicated that maximum measurement differences of 3 mm have to be expected with two calibrated observers. In vivo: the EPI sequence for brain imaging was not analysable. The TSE sequence of the brain did not demonstrate artefacts except for the nasal cavity. Conversely, the TSE sequence of the cervical spine revealed severe artefacts in the midface region. The GRE sequence appeared to be more susceptible to artefacts than did the TSE sequence. In vitro measurements allow an estimation of the in vivo artefact size. Orthodontic appliances may often remain intraorally when performing MRI. WARP showed a more significant effect in vitro than in vivo.

Understanding sudden environmental and societal change through coupled geochronological and artefact shape analyses

DEFF Research Database (Denmark)

Hoggard, Christian Steven; Sauer, Florian Rudolf; Zernack, Anke Verena

Over the last twenty years, advances in geometric morphometric methodologies have revolutionised how archaeologists understand changes in artefact shape and form (size plus shape) throughout the Quaternary period. Such methodologies provide a high resolution of artefact coverage, and allow...... a critical analysis of previous taxonomic classificatory schemas and human tool-use in the past. Despite this, methodologies into artefact shape through geometric morphometrics have not been integrated within extensive geochronological data to better understand periods of high environmental stress and......, with respect to archaeology, how past societies reacted to such stress. The Laacher See volcanic eruption (c. 13,000 BP) in western Germany is believed, given its hypothesised characteristics, to have had profound impact on the lifeways of hunter-gatherers towards the end of the Final Palaeolithic (Riede, 2017...

Non-invasive NMR stratigraphy of a multi-layered artefact: an ancient detached mural painting.

Science.gov (United States)

Di Tullio, Valeria; Capitani, Donatella; Presciutti, Federica; Gentile, Gennaro; Brunetti, Brunetto Giovanni; Proietti, Noemi

2013-10-01

NMR stratigraphy was used to investigate in situ, non-destructively and non-invasively, the stratigraphy of hydrogen-rich layers of an ancient Nubian detached mural painting. Because of the detachment procedure, a complex multi-layered artefact was obtained, where, besides layers of the original mural painting, also the materials used during the procedure all became constitutive parts of the artefact. NMR measurements in situ enabled monitoring of the state of conservation of the artefact and planning of minimum representative sampling to validate results obtained in situ by solid-state NMR analysis of the samples. This analysis enabled chemical characterization of all organic materials. Use of reference compounds and prepared specimens assisted data interpretation.

Stratigraphy, artefact industries and hominid associations for Sterkfontein, member 5.

Science.gov (United States)

Kuman, K; Clarke, R J

2000-06-01

A revised stratigraphy for the early hominid site of Sterkfontein (Gauteng Province, South Africa) reveals a complex distribution of infills in the main excavation area between 2.8 and 1.4 m.y.a, as well as deposits dating to the mid to late Pleistocene. New research now shows that the Member 4 australopithecine breccia (2.8-2.6 Ma) extends further west than was previously thought, while a late phase of Member 4 is recognized in a southern area. The artefact-bearing breccias were defined sedimentologically as Member 5, but one supposed part of these younger breccias, the StW 53 infill, lacks in situ stone tools, although it does appear to post-date 2.6 Ma when artefacts first appear in the archaeological record. The StW 53 hominid, previously referred to Homo habilis, is here argued to be Australopithecus. The first artefact-bearing breccia of Member 5 is the Oldowan Infill, estimated at 2-1.7 Ma. It occupies a restricted distribution in Member 5 east and contains an expedient, flake-based tool industry associated with a few fossils of Paranthropos robustus. An enlarged cave opening subsequently admitted one or more Early Acheulean infills associated in Member 5 west with Homo ergaster. The artefacts attest to a larger site accumulation between ca. 1.7 and 1.4 Ma, with more intensive use of quartzite over quartz and a subtle but important shift to large flakes and heavier-duty tools. The available information on palaeoenvironments is summarized, showing an overall change from tropical to sub-tropical gallery forest, forest fringe and woodland conditions in Member 4 to more open woodland and grassland habitats in the later units, but with suggestions of a wet localized topography in the Paranthropus -bearing Oldowan Infill. Copyright 2000 Academic Press.

3D Visualization of Cultural Heritage Artefacts with Virtual Reality devices

Science.gov (United States)

Gonizzi Barsanti, S.; Caruso, G.; Micoli, L. L.; Covarrubias Rodriguez, M.; Guidi, G.

2015-08-01

Although 3D models are useful to preserve the information about historical artefacts, the potential of these digital contents are not fully accomplished until they are not used to interactively communicate their significance to non-specialists. Starting from this consideration, a new way to provide museum visitors with more information was investigated. The research is aimed at valorising and making more accessible the Egyptian funeral objects exhibited in the Sforza Castle in Milan. The results of the research will be used for the renewal of the current exhibition, at the Archaeological Museum in Milan, by making it more attractive. A 3D virtual interactive scenario regarding the "path of the dead", an important ritual in ancient Egypt, was realized to augment the experience and the comprehension of the public through interactivity. Four important artefacts were considered for this scope: two ushabty, a wooden sarcophagus and a heart scarab. The scenario was realized by integrating low-cost Virtual Reality technologies, as the Oculus Rift DK2 and the Leap Motion controller, and implementing a specific software by using Unity. The 3D models were implemented by adding responsive points of interest in relation to important symbols or features of the artefact. This allows highlighting single parts of the artefact in order to better identify the hieroglyphs and provide their translation. The paper describes the process for optimizing the 3D models, the implementation of the interactive scenario and the results of some test that have been carried out in the lab.

3D Visualization of Cultural Heritage Artefacts with Virtual Reality devices

Directory of Open Access Journals (Sweden)

S. Gonizzi Barsanti

2015-08-01

Full Text Available Although 3D models are useful to preserve the information about historical artefacts, the potential of these digital contents are not fully accomplished until they are not used to interactively communicate their significance to non-specialists. Starting from this consideration, a new way to provide museum visitors with more information was investigated. The research is aimed at valorising and making more accessible the Egyptian funeral objects exhibited in the Sforza Castle in Milan. The results of the research will be used for the renewal of the current exhibition, at the Archaeological Museum in Milan, by making it more attractive. A 3D virtual interactive scenario regarding the “path of the dead”, an important ritual in ancient Egypt, was realized to augment the experience and the comprehension of the public through interactivity. Four important artefacts were considered for this scope: two ushabty, a wooden sarcophagus and a heart scarab. The scenario was realized by integrating low-cost Virtual Reality technologies, as the Oculus Rift DK2 and the Leap Motion controller, and implementing a specific software by using Unity. The 3D models were implemented by adding responsive points of interest in relation to important symbols or features of the artefact. This allows highlighting single parts of the artefact in order to better identify the hieroglyphs and provide their translation. The paper describes the process for optimizing the 3D models, the implementation of the interactive scenario and the results of some test that have been carried out in the lab.

Artefacts in multimodal imaging of titanium, zirconium and binary titanium-zirconium alloy dental implants: an in vitro study.

Science.gov (United States)

Smeets, Ralf; Schöllchen, Maximilian; Gauer, Tobias; Aarabi, Ghazal; Assaf, Alexandre T; Rendenbach, Carsten; Beck-Broichsitter, Benedicta; Semmusch, Jan; Sedlacik, Jan; Heiland, Max; Fiehler, Jens; Siemonsen, Susanne

2017-02-01

To analyze and evaluate imaging artefacts induced by zirconium, titanium and titanium-zirconium alloy dental implants. Zirconium, titanium and titanium-zirconium alloy implants were embedded in gelatin and MRI, CT and CBCT were performed. Standard protocols were used for each modality. For MRI, line-distance profiles were plotted to quantify the accuracy of size determination. For CT and CBCT, six shells surrounding the implant were defined every 0.5 cm from the implant surface and histogram parameters were determined for each shell. While titanium and titanium-zirconium alloy induced extensive signal voids in MRI owing to strong susceptibility, zirconium implants were clearly definable with only minor distortion artefacts. For titanium and titanium-zirconium alloy, the MR signal was attenuated up to 14.1 mm from the implant. In CT, titanium and titanium-zirconium alloy resulted in less streak artefacts in comparison with zirconium. In CBCT, titanium-zirconium alloy induced more severe artefacts than zirconium and titanium. MRI allows for an excellent image contrast and limited artefacts in patients with zirconium implants. CT and CBCT examinations are less affected by artefacts from titanium and titanium-zirconium alloy implants compared with MRI. The knowledge about differences of artefacts through different implant materials and image modalities might help support clinical decisions for the choice of implant material or imaging device in the clinical setting.

Artefacts in multimodal imaging of titanium, zirconium and binary titanium–zirconium alloy dental implants: an in vitro study

Science.gov (United States)

Schöllchen, Maximilian; Aarabi, Ghazal; Assaf, Alexandre T; Rendenbach, Carsten; Beck-Broichsitter, Benedicta; Semmusch, Jan; Sedlacik, Jan; Heiland, Max; Fiehler, Jens; Siemonsen, Susanne

2017-01-01

Objectives: To analyze and evaluate imaging artefacts induced by zirconium, titanium and titanium–zirconium alloy dental implants. Methods: Zirconium, titanium and titanium–zirconium alloy implants were embedded in gelatin and MRI, CT and CBCT were performed. Standard protocols were used for each modality. For MRI, line–distance profiles were plotted to quantify the accuracy of size determination. For CT and CBCT, six shells surrounding the implant were defined every 0.5 cm from the implant surface and histogram parameters were determined for each shell. Results: While titanium and titanium–zirconium alloy induced extensive signal voids in MRI owing to strong susceptibility, zirconium implants were clearly definable with only minor distortion artefacts. For titanium and titanium–zirconium alloy, the MR signal was attenuated up to 14.1 mm from the implant. In CT, titanium and titanium–zirconium alloy resulted in less streak artefacts in comparison with zirconium. In CBCT, titanium–zirconium alloy induced more severe artefacts than zirconium and titanium. Conclusions: MRI allows for an excellent image contrast and limited artefacts in patients with zirconium implants. CT and CBCT examinations are less affected by artefacts from titanium and titanium–zirconium alloy implants compared with MRI. The knowledge about differences of artefacts through different implant materials and image modalities might help support clinical decisions for the choice of implant material or imaging device in the clinical setting. PMID:27910719

MRI with intraoral orthodontic appliance—a comparative in vitro and in vivo study of image artefacts at 1.5 T

Science.gov (United States)

Zachriat, C; Asbach, P; Blankenstein, K I; Peroz, I

2015-01-01

Objectives: We investigated artefacts caused from orthodontic appliances at 1.5-T MRI of the head and neck region and whether the image quality can be improved utilizing the artefact-minimizing sequence WARP. Methods: In vitro tests were performed by phantom measurements of different orthodontic devices applying different types of MR sequences [echoplanar imaging (EPI), turbo spin echo (TSE) and TSE-WARP, gradient echo (GRE)]. Two independent readers determined after calibration the level of artefacts. Subsequently, the interobserver agreement was calculated. The measurement of artefacts was based on the American Society for Testing Materials Standard F 2119-07. For in vivo imaging, one test person was scanned with an inserted multibracket appliance. The level of artefacts for 27 target regions was evaluated. Results: In vitro: ceramic brackets and ferromagnetic steel brackets produced artefact radii up to 1.12 and 7.40 cm, respectively. WARP reduced these artefacts by an average of 32.7%. The Bland–Altman-Plot indicated that maximum measurement differences of 3 mm have to be expected with two calibrated observers. In vivo: the EPI sequence for brain imaging was not analysable. The TSE sequence of the brain did not demonstrate artefacts except for the nasal cavity. Conversely, the TSE sequence of the cervical spine revealed severe artefacts in the midface region. The GRE sequence appeared to be more susceptible to artefacts than did the TSE sequence. Conclusions: In vitro measurements allow an estimation of the in vivo artefact size. Orthodontic appliances may often remain intraorally when performing MRI. WARP showed a more significant effect in vitro than in vivo. PMID:25734243

Comparison of two ring artefact removal filters used for neutron tomography reconstruction

International Nuclear Information System (INIS)

Vontobel, P.

2007-01-01

Full text of publication follows: The reduction of ring artefacts in transmission tomography reconstruction, by filtering sino-grams, is a common practice for most radiation modalities. Using simulated and measured neutron transmission data, an analysis of two ring artefact suppression schemes is given. The choice of the ring filtering parameters has to take the noise characteristics of the measured raw projection data into account. Introduction The appearance of ring artefacts in transmission tomography data is quite common. They are due to deficiencies in the measured projections and show as vertical lines in the sinogram representation of all projections of a single slice. A vertical line in the sinogram is due to a single pixel or a group of n pixels on the detector, which is less or more sensitive than the average pixel and shows even after flat-field correction. Most annoying ring artefacts are due to partly dead pixels, which cannot be identified easily on the projection images. Their effect only show in the sinogram or later on the reconstructed slice images. Therefore ring artefact mitigation starts with the analysis of sinogram images or analysis of reconstructed slices. Analysis of two ring filtering algorithms: The first ring filtering method sums first sinogram rows (i.e. over all angles) and divides it by the number of rows (ave) and generate a smoothed version of this sum (smoothing width 3,5,7,9 pixels). The difference diff = ave - smooth(ave) is then subtracted from each row. This is a very simple and efficient correction scheme. The second method relies on morphological filtering the sinogram i.e. using a combination of a morphological 'Top hat' and a 'Bot hat' operation on the data. A filtering threshold is determined depending on the number of detected lines in the sinogram. Summary and conclusion: Using simulated an measured neutron transmission data two ring filtering algorithms are evaluated. A careful choice of filtering parameters is

Metal artefact reduction for a dental cone beam CT image using image segmentation and backprojection filters

International Nuclear Information System (INIS)

Mohammadi, Mahdi; Khotanlou, Hassan; Mohammadi, Mohammad

2011-01-01

Full text: Due to low dose delivery and fast scanning, the dental Cone Beam CT (CBCT) is the latest technology being implanted for a range of dental imaging. The presence of metallic objects including amalgam or gold fillings in the mouth produces an intuitive image for human jaws. The feasibility of a fast and accurate approach for metal artefact reduction for dental CBCT is investigated. The current study investigates the metal artefact reduction using image segmentation and modification of several sinigrams. In order to reduce metal effects such as beam hardening, streak artefact and intense noises, the application of several algorithms is evaluated. The proposed method includes three stages: preprocessing, reconstruction and post-processing. In the pre-processing stage, in order to reduce the noise level, several phase and frequency filters were applied. At the second stage, based on the specific sinogram achieved for each segment, spline interpolation and weighting backprojection filters were applied to reconstruct the original image. A three-dimensional filter was then applied on reconstructed images, to improve the image quality. Results showed that compared to other available filters, standard frequency filters have a significant influence in the preprocessing stage (ΔHU = 48 ± 6). In addition, with the streak artefact, the probability of beam hardening artefact increases. t e post-processing stage, the application of three-dimensional filters improves the quality of reconstructed images (See Fig. I). Conclusion The proposed method reduces metal artefacts especially where there are more than one metal implanted in the region of interest.

Influence of chest compression artefact on capnogram-based ventilation detection during out-of-hospital cardiopulmonary resuscitation.

Science.gov (United States)

Leturiondo, Mikel; Ruiz de Gauna, Sofía; Ruiz, Jesus M; Julio Gutiérrez, J; Leturiondo, Luis A; González-Otero, Digna M; Russell, James K; Zive, Dana; Daya, Mohamud

2018-03-01

Capnography has been proposed as a method for monitoring the ventilation rate during cardiopulmonary resuscitation (CPR). A high incidence (above 70%) of capnograms distorted by chest compression induced oscillations has been previously reported in out-of-hospital (OOH) CPR. The aim of the study was to better characterize the chest compression artefact and to evaluate its influence on the performance of a capnogram-based ventilation detector during OOH CPR. Data from the MRx monitor-defibrillator were extracted from OOH cardiac arrest episodes. For each episode, presence of chest compression artefact was annotated in the capnogram. Concurrent compression depth and transthoracic impedance signals were used to identify chest compressions and to annotate ventilations, respectively. We designed a capnogram-based ventilation detection algorithm and tested its performance with clean and distorted episodes. Data were collected from 232 episodes comprising 52 654 ventilations, with a mean (±SD) of 227 (±118) per episode. Overall, 42% of the capnograms were distorted. Presence of chest compression artefact degraded algorithm performance in terms of ventilation detection, estimation of ventilation rate, and the ability to detect hyperventilation. Capnogram-based ventilation detection during CPR using our algorithm was compromised by the presence of chest compression artefact. In particular, artefact spanning from the plateau to the baseline strongly degraded ventilation detection, and caused a high number of false hyperventilation alarms. Further research is needed to reduce the impact of chest compression artefact on capnographic ventilation monitoring. Copyright © 2017 Elsevier B.V. All rights reserved.

Thermal Effects That Arise upon Different Heat Treatments in Austenitic Steels Alloyed with Titanium and Phosphorus

Science.gov (United States)

Arbuzov, V. L.; Berger, I. F.; Bobrovskii, V. I.; Voronin, V. I.; Danilov, S. E.; Kazantsev, V. A.; Kataev, N. V.; Sagaradze, V. V.

2018-04-01

Structural and microstructural changes that arise in the course of the heat treatment of Cr-Ni-Mo austenitic stainless steels with different concentrations of titanium and phosphorus have been studied. It has been found that the alloying with phosphorus decreases the lattice parameter of these steels. The phosphorus contribution to this effect is 0.015 ± 0.002 Å/at %. Aging at a temperature of 670 K for about 20 h leads to the precipitation of dispersed needle-like particles, which are most likely to be iron phosphides. In the temperature range of 700-800 K, in austenitic steels, the atomic separation of the solid solution occurs, the intensity of which decreases upon alloying with titanium or phosphorus at concentrations of 1.0 and 0.1 wt %, respectively. At higher temperatures (about 950 K), the formed precipitates of the Ni3Ti (γ') phase increase in size to 7-10 nm.

Beyond tokenistic participation: using representational artefacts to enable meaningful public participation in health service design.

Science.gov (United States)

Morrison, Cecily; Dearden, Andy

2013-10-01

A number of recent policies promote public participation in health service design. Yet, a growing literature has articulated a gap between policy aims and actual practice resulting in public participation becoming tokenistic. Drawing on theory from participatory design, we argue that choosing appropriate artefacts to act as representations can structure discussions between public participants and health professionals in ways that both groups find meaningful and valid. Through a case study of a service improvement project in outpatient services for older people, we describe three representational artefacts: emotion maps, stories, and tracing paper, and explain how they helped to mediate interactions between public participants and health professionals. We suggest that using such representational artefacts can provide an alternative approach to participation that stands in contrast to the current focus on the professionalisation of public participants. We conclude that including participatory designers in projects, to chose or design appropriate representational artefacts, can help to address the policy-practice gap of including public participants in health service design. Copyright © 2013 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

Future heat stress arising from climate change on Iran's population health

Science.gov (United States)

Modarres, Reza; Ghadami, Mohammad; Naderi, Sohrab; Naderi, Mohammad

2018-04-01

Climate change-induced extreme heat events are becoming a major issue in different parts of the world, especially in developing countries. The assessment of regional and temporal past and future change in heat waves is a crucial task for public health strategies and managements. The historical and future heat index (HI) time series are investigated for temporal change across Iran to study the impact of global warming on public health. The heat index is calculated, and the nonparametric trend assessment is carried out for historical time series (1981-2010). The future change in heat index is also projected for 2020-2049 and 2070-2099 periods. A rise in the historical heat index and extreme caution conditions for summer and spring seasons for major parts of Iran are notable for historical (1981-2010) series in this study. Using different climate change scenarios shows that heat index will exceed the critical threshold for human adaptability in the future in the country. The impact of climate change on heat index risk in Iran is significant in the future. To cope with this crucial situation, developing early warning systems and health care strategies to deal with population growth and remarkable socio-economic features in future is essential.

An Evaluation View of an Ensemble Artefact for Decision Support using Action Design Research

Directory of Open Access Journals (Sweden)

Dale MacKrell

2016-11-01

Full Text Available This paper investigates the integration of content, context and process (CCP into the Action Design Research (ADR framework to account for the interplay of organisational issues in artefact design and development. The investigation is conducted through a case study in which successive ICT student teams incrementally build, over several semesters, a tailored, low cost business intelligence (BI system as an ensemble artefact for an organisation in the not-for-profit (NFP sector. During project development, CCP’s human-centred approach to evaluation complements ADR’s more prescribed technology-driven software testing. The integration of CCP into ADR as an evaluation view offers an holistic approach to assessing an ensemble artefact. The resultant conceptual framework is presented as a model with an explication of unexpected design and research outcomes.

Magnetic resonance angiography with ultrashort echo times reduces the artefact of aneurysm clips

International Nuclear Information System (INIS)

Goenner, F.; Heid, O.; Remonda, L.; Schroth, G.; Loevblad, K.O.; Guzman, R.; Barth, A.

2002-01-01

We evaluated the ability of an ultrashort echo time (TE) three-dimensional (3D) time-of-flight (TOF) magnetic resonance angiography (MRA) sequence to reduce the metal artefact of intracranial aneurysm clips and to display adjacent cerebral arteries. In five patients (aged 8-72 years) treated with Elgiloy or Phynox aneurysm clips we prospectively performed a conventional (TE 6.0 ms) and a new ultrashort TE (TE 2.4 ms) 3D TOF MRA. We compared the diameter of the clip-induced susceptibility artefact and the detectability of flow in adjacent vessels. The mean artefact diameter was 22.3±6.4 mm (range 14-38 mm) with the ultrashort TE and 27.7±6.4 mm (range 19-45 mm) with the conventional MRA (P<0.0001). This corresponded to a diameter reduction of 19.5±9.2%. More parts of adjacent vessels were detected, but with less intense flow signal. The aneurysm dome and neck remained within the area of signal loss and were therefore not displayed. Ultrashort TE MRA is a noninvasive and fast method for improving detection of vessels adjacent to clipped intracranial aneurysms, by reducing clip-induced susceptibility artefact. The method cannot, however, be used to show remnants of the aneurysm neck or sac as a result of imperfect clipping. (orig.)

Analysis artefacts of the INS-IGF2 fusion transcript

DEFF Research Database (Denmark)

Wernersson, Rasmus; Frogne, Thomas; Rescan, Claude

2015-01-01

Background: In gene expression analysis, overlapping genes, splice variants, and fusion transcripts are potential sources of data analysis artefacts, depending on how the observed intensity is assigned to one, or more genes. We here exemplify this by an in-depth analysis of the INS-IGF2 fusion...... transcript, which has recently been reported to be among the highest expressed transcripts in human pancreatic beta cells and its protein indicated as a novel autoantigen in Type 1 Diabetes. Results: Through RNA sequencing and variant specific qPCR analyses we demonstrate that the true abundance of INS-IGF2...... is >20,000 fold lower than INS in human beta cells, and we suggest an explanation to the nature of the artefacts which have previously led to overestimation of the gene expression level in selected studies. We reinvestigated the previous reported findings of detection of INS-IGF2 using antibodies both...

Influence of metallic dental implants and metal artefacts on dose calculation accuracy.

Science.gov (United States)

Maerz, Manuel; Koelbl, Oliver; Dobler, Barbara

2015-03-01

Metallic dental implants cause severe streaking artefacts in computed tomography (CT) data, which inhibit the correct representation of shape and density of the metal and the surrounding tissue. The aim of this study was to investigate the impact of dental implants on the accuracy of dose calculations in radiation therapy planning and the benefit of metal artefact reduction (MAR). A second aim was to determine the treatment technique which is less sensitive to the presence of metallic implants in terms of dose calculation accuracy. Phantoms consisting of homogeneous water equivalent material surrounding dental implants were designed. Artefact-containing CT data were corrected using the correct density information. Intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) plans were calculated on corrected and uncorrected CT data and compared to 2-dimensional dose measurements using GafChromic™ EBT2 films. For all plans the accuracy of dose calculations is significantly higher if performed on corrected CT data (p = 0.015). The agreement of calculated and measured dose distributions is significantly higher for VMAT than for IMRT plans for calculations on uncorrected CT data (p = 0.011) as well as on corrected CT data (p = 0.029). For IMRT and VMAT the application of metal artefact reduction significantly increases the agreement of dose calculations with film measurements. VMAT was found to provide the highest accuracy on corrected as well as on uncorrected CT data. VMAT is therefore preferable over IMRT for patients with metallic implants, if plan quality is comparable for the two techniques.

Influence of metallic dental implants and metal artefacts on dose calculation accuracy

International Nuclear Information System (INIS)

Maerz, Manuel; Koelbl, Oliver; Dobler, Barbara

2015-01-01

Metallic dental implants cause severe streaking artefacts in computed tomography (CT) data, which inhibit the correct representation of shape and density of the metal and the surrounding tissue. The aim of this study was to investigate the impact of dental implants on the accuracy of dose calculations in radiation therapy planning and the benefit of metal artefact reduction (MAR). A second aim was to determine the treatment technique which is less sensitive to the presence of metallic implants in terms of dose calculation accuracy. Phantoms consisting of homogeneous water equivalent material surrounding dental implants were designed. Artefact-containing CT data were corrected using the correct density information. Intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) plans were calculated on corrected and uncorrected CT data and compared to 2-dimensional dose measurements using GafChromic trademark EBT2 films. For all plans the accuracy of dose calculations is significantly higher if performed on corrected CT data (p = 0.015). The agreement of calculated and measured dose distributions is significantly higher for VMAT than for IMRT plans for calculations on uncorrected CT data (p = 0.011) as well as on corrected CT data (p = 0.029). For IMRT and VMAT the application of metal artefact reduction significantly increases the agreement of dose calculations with film measurements. VMAT was found to provide the highest accuracy on corrected as well as on uncorrected CT data. VMAT is therefore preferable over IMRT for patients with metallic implants, if plan quality is comparable for the two techniques. (orig.) [de

Is metal artefact reduction mandatory in cardiac PET/CT imaging in the presence of pacemaker and implantable cardioverter defibrillator leads?

Energy Technology Data Exchange (ETDEWEB)

Ghafarian, Pardis [Shahid Beheshti University, Department of Radiation Medicine, Tehran (Iran, Islamic Republic of); Geneva University Hospital, Division of Nuclear Medicine, Geneva 4 (Switzerland); Tehran University of Medical Sciences, Research Center for Science and Technology in Medicine, Tehran (Iran, Islamic Republic of); Aghamiri, S.M.R. [Shahid Beheshti University, Department of Radiation Medicine, Tehran (Iran, Islamic Republic of); Ay, Mohammad R. [Tehran University of Medical Sciences, Research Center for Science and Technology in Medicine, Tehran (Iran, Islamic Republic of); Tehran University of Medical Sciences, Department of Medical Physics and Biomedical Engineering, Tehran (Iran, Islamic Republic of); Tehran University of Medical Sciences, Research Institute for Nuclear Medicine, Tehran (Iran, Islamic Republic of); Rahmim, Arman [Johns Hopkins University, Department of Radiology, Baltimore, MD (United States); Schindler, Thomas H. [Geneva University, Cardiovascular Center, Nuclear Cardiology, Geneva (Switzerland); Ratib, Osman [Geneva University Hospital, Division of Nuclear Medicine, Geneva 4 (Switzerland); Zaidi, Habib [Geneva University Hospital, Division of Nuclear Medicine, Geneva 4 (Switzerland); Geneva University, Geneva Neuroscience Center, Geneva (Switzerland)

2011-02-15

Cardiac PET/CT imaging is often performed in patients with pacemakers and implantable cardioverter defibrillator (ICD) leads. However, metallic implants usually produce artefacts on CT images which might propagate to CT-based attenuation-corrected (CTAC) PET images. The impact of metal artefact reduction (MAR) for CTAC of cardiac PET/CT images in the presence of pacemaker, ICD and ECG leads was investigated using both qualitative and quantitative analysis in phantom and clinical studies. The study included 14 patients with various leads undergoing perfusion and viability examinations using dedicated cardiac PET/CT protocols. The PET data were corrected for attenuation using both artefactual CT images and CT images corrected using the MAR algorithm. The severity and magnitude of metallic artefacts arising from these leads were assessed on both linear attenuation coefficient maps ({mu}-maps) and attenuation-corrected PET images. CT and PET emission data were obtained using an anthropomorphic thorax phantom and a dedicated heart phantom made in-house incorporating pacemaker and ICD leads attached at the right ventricle of the heart. Volume of interest-based analysis and regression plots were performed for regions related to the lead locations. Bull's eye view analysis was also performed on PET images corrected for attenuation with and without the MAR algorithm. In clinical studies, the visual assessment of PET images by experienced physicians and quantitative analysis did not reveal erroneous interpretation of the tracer distribution or significant differences when PET images were corrected for attenuation with and without MAR. In phantom studies, the mean differences between tracer uptake obtained without and with MAR were 10.16{+-}2.1% and 6.86{+-}2.1% in the segments of the heart in the vicinity of metallic ICD or pacemaker leads, and were 4.43{+-}0.5% and 2.98{+-}0.5% in segments far from the leads. Although the MAR algorithm was able to effectively improve

What Then Happens When Interaction is Not Possible: The Virtuosic Interpretation of Ergodic Artefacts

Directory of Open Access Journals (Sweden)

Miguel Carvalhais

2015-11-01

Full Text Available Procedural systems allow unique modes of authorship and singular aesthetic experiences. As creators and users of these systems, we need to be aware that their aesthetic potential is not solely defined by interaction but that interpretation, and the capacity to understand and simulate the processes taking place within these artefacts is highly significant. This paper argues that although direct interaction is usually the most discernible component in the relationship between ergodic artefacts and their users, ergodicity does not necessarily imply interaction. Non-interactive procedural artefacts may allow the development of ergodic experiences through interpretation, and the probing of the system by its reader through simulations. We try to set the grounds for designing towards virtuosic interpretation, an activity that we may describe as the ergodic experience developed by means of mental simulation through the development of theories of systems.

Transforming Artefacts into Digital Heritage

DEFF Research Database (Denmark)

Otto, Ton; Hardy, Dianna

2016-01-01

a genuine transformation of the artefacts that opens up new possibilities of use. These include providing access to and facilitating the reappropriation of cultural knowledge stored elsewhere, maintaining and developing a living digital cultural heritage, and gathering, sharing and transferring knowledge...... that is available within Aboriginal communities. In this paper we examine different types of digital repositories and we assess their suitability for use by Aboriginal communities. We classify a number of institutional archiving systems and analyse in some detail two interactive systems that were specifically...... designed for use by Aboriginal communities. The paper ends with a set of recommendations for designing digital databases for Indigenous usage....

Triangular dislocation: an analytical, artefact-free solution

Science.gov (United States)

Nikkhoo, Mehdi; Walter, Thomas R.

2015-05-01

Displacements and stress-field changes associated with earthquakes, volcanoes, landslides and human activity are often simulated using numerical models in an attempt to understand the underlying processes and their governing physics. The application of elastic dislocation theory to these problems, however, may be biased because of numerical instabilities in the calculations. Here, we present a new method that is free of artefact singularities and numerical instabilities in analytical solutions for triangular dislocations (TDs) in both full-space and half-space. We apply the method to both the displacement and the stress fields. The entire 3-D Euclidean space {R}3 is divided into two complementary subspaces, in the sense that in each one, a particular analytical formulation fulfils the requirements for the ideal, artefact-free solution for a TD. The primary advantage of the presented method is that the development of our solutions involves neither numerical approximations nor series expansion methods. As a result, the final outputs are independent of the scale of the input parameters, including the size and position of the dislocation as well as its corresponding slip vector components. Our solutions are therefore well suited for application at various scales in geoscience, physics and engineering. We validate the solutions through comparison to other well-known analytical methods and provide the MATLAB codes.

Comparison of CT and MRI artefacts from coils and vascular plugs used for portal vein embolization

Energy Technology Data Exchange (ETDEWEB)

Geisel, Dominik, E-mail: dominik.geisel@charite.de [Department of Diagnostic and Interventional Radiology, Charité, Campus Virchow-Klinikum, Augustenburger Platz 1, 13353 Berlin (Germany); Gebauer, Bernhard [Department of Diagnostic and Interventional Radiology, Charité, Campus Virchow-Klinikum, Augustenburger Platz 1, 13353 Berlin (Germany); Malinowski, Maciej; Stockmann, Martin [Department of General, Visceral and Transplantation Surgery, Charité, Campus Virchow-Klinikum, Augustenburger Platz 1, 13353 Berlin (Germany); Denecke, Timm [Department of Diagnostic and Interventional Radiology, Charité, Campus Virchow-Klinikum, Augustenburger Platz 1, 13353 Berlin (Germany)

2014-04-15

Purpose: To retrospectively analyze the degree of artefacts in CT and MRI scans caused by coils and vascular plugs used for portal vein embolization (PVE). Materials and methods: All patients who underwent PVE between July 2011 and December 2012 and received either plug or coil embolization additional to particle embolization were retrospectively analyzed. Artefacts causes by embolization materials were measured in CT and MRI scans following PVE. Results: The sum of the artefact diameters caused from coils was significantly higher in CT (188.3 ± 26.1 mm) than in MRI T1 (50.5 ± 6.5 mm) or T2 imaging (39.5 ± 9.7 mm) (P < 0.05). In MRI, the diameter in T1 and T2 sequences did not differ significantly (P = 0.977). The sum of the artefact diameters from vascular plugs in MRI T1 sequences (62.5 ± 8.7 mm) was significantly higher than in CT (46.6 ± 4.8 mm; P < 0.05) and MRI T2 sequences (52.8 ± 3.8 mm; P < 0.05). Conclusion: PVE with particles and vascular plug causes significantly fewer artefacts than PVE with particles and coils on CT scans following embolization, which can be important in the event of vascular complications or in follow-up scans, should the patient become unresectable.

Reduced artefacts and improved assessment of hyperintense brain lesions with BLADE MR imaging in patients with neurofibromatosis type 1

Energy Technology Data Exchange (ETDEWEB)

Kalle, Thekla von; Fabig-Moritz, Claudia; Mueller-Abt, Peter; Zieger, Michael; Winkler, Peter [Department of Paediatric Radiology, Stuttgart (Germany); Blank, Bernd [Haematology and Immunology, Department of Paediatric Oncology, Stuttgart (Germany); Wohlfarth, Katrin [Siemens Healthcare Sector, Erlangen (Germany)

2009-11-15

Assessment of small brain lesions in children is often compromised by pulsation, flow or movement artefacts. MRI with a rotating blade-like k-space covering (BLADE, PROPELLER) can compensate for these artefacts. We compared T2-weighted FLAIR images that were acquired with different k-space trajectories (conventional Cartesian and BLADE) to evaluate the impact of BLADE technique on the delineation of small or low-contrast brain lesions. The subject group comprised 26 children with neurofibromatosis type 1 (NF 1), who had been routinely scanned at 1.5 T for optic pathway gliomas with both techniques and who had the typical hyperintense brain lesions seen in NF 1. Four experienced radiologists retrospectively compared unlabelled 4-mm axial images with respect to the presence of artefacts, visibility of lesions, quality of contour and contrast. Both techniques were comparable in depicting hyperintense lesions as small as 2 mm independent of contrast and edge definition. Pulsation and movement artefacts were significantly less common with BLADE k-space trajectory. In 7 of 26 patients (27%), lesions and artefacts were rated as indistinguishable in conventional FLAIR, but not in BLADE FLAIR images. BLADE imaging significantly improved the depiction of lesions in T2-W FLAIR images due to artefact reduction especially in the posterior fossa. (orig.)

Reduced artefacts and improved assessment of hyperintense brain lesions with BLADE MR imaging in patients with neurofibromatosis type 1

International Nuclear Information System (INIS)

Kalle, Thekla von; Fabig-Moritz, Claudia; Mueller-Abt, Peter; Zieger, Michael; Winkler, Peter; Blank, Bernd; Wohlfarth, Katrin

2009-01-01

Assessment of small brain lesions in children is often compromised by pulsation, flow or movement artefacts. MRI with a rotating blade-like k-space covering (BLADE, PROPELLER) can compensate for these artefacts. We compared T2-weighted FLAIR images that were acquired with different k-space trajectories (conventional Cartesian and BLADE) to evaluate the impact of BLADE technique on the delineation of small or low-contrast brain lesions. The subject group comprised 26 children with neurofibromatosis type 1 (NF 1), who had been routinely scanned at 1.5 T for optic pathway gliomas with both techniques and who had the typical hyperintense brain lesions seen in NF 1. Four experienced radiologists retrospectively compared unlabelled 4-mm axial images with respect to the presence of artefacts, visibility of lesions, quality of contour and contrast. Both techniques were comparable in depicting hyperintense lesions as small as 2 mm independent of contrast and edge definition. Pulsation and movement artefacts were significantly less common with BLADE k-space trajectory. In 7 of 26 patients (27%), lesions and artefacts were rated as indistinguishable in conventional FLAIR, but not in BLADE FLAIR images. BLADE imaging significantly improved the depiction of lesions in T2-W FLAIR images due to artefact reduction especially in the posterior fossa. (orig.)

FT-Raman and FT-Infrared investigations of archaeological artefacts from Foeni Neolithic site (Banat, Romania

Directory of Open Access Journals (Sweden)

Simona Cîntă Pînzaru

2008-08-01

Full Text Available An impressive collection of chert artefacts from the Foeni Neolithic archaeological site (Timiş County, Banat region, Romania is hosted by the Banat Museum in Timişoara. A representative set of seven specimens was non-destructively investigated using FT-Raman and ATR-FT-IR spectroscopy. The research was carried out for checking if these readily-available, non-destructive, fast, and cheap methods, which do not require preliminary sample preparation could provide significant information for characterizing the mineral composition of chert artefacts. Based on vibrational data, it was confirmed that the raw material was represented by microcrystalline quartz and moganite, with local concentrations of accessory minerals (calcite, dolomite, and clay minerals. In spite of their wide macroscopic heterogeneity (colour, transparency, based on single point FT-Raman measurements the chert artefacts could not be assigned to distinctive groups of raw silica materials, in order to provide specific arguments for provenance studies. However, the presence of specific accessory minerals (dolomite, illite pointed to distinctive genetic conditions in the case of one lithic material. Sets of measurements (mapping are required for statistically characterizing each artefact specimen. IR data were less significant, due to the rough surface texture of the specimens in contact with the ZnSe crystal of the ATR-FT-IR module. However, illite was identified based solely on its contribution to the IR spectrum. This pioneering study on chert artefacts from Romania based on optical spectroscopic methods shows that there are good premises for a systematic investigation of highly-valuable museum collections, in particular in terms of chert geology.

Persistent Artefacts in an Online Classroom: The Value of a Dynamic Learning Archive | Artefacts persistants dans une salle de classe en ligne : la valeur d’une archive dynamique de l’apprentissage

Directory of Open Access Journals (Sweden)

Stuart C. Berry

2016-04-01

Full Text Available This paper summarizes a multi-year research project that examines the use and value of visible and persistent artefacts within an online learning environment. This study is framed within elements of a business management theory. Changes to an online learning environment are documented as well as an examination of the impact of these changes on the learning process. The study also shows the impact of learner engagement with artefacts over the life of multiple iterations of a course within this socially networked online learning space. Two significant outcomes emerged: 1. How the use of a socially networked online learning environment can offer a rich and supportive place for teaching and learning; and 2. That students in this study support the inclusion of an archive containing artefacts from learners in prior iterations of a course. The connection between the inclusion of this archive and the impact of a socially networked online learning environment will be demonstrated throughout. Cet article résume un projet de recherche sur plusieurs années, examinant l’utilisation et la valeur des artefacts visibles et persistants au sein d’un environnement d’apprentissage en ligne. Cette étude a été structurée selon des éléments d’une théorie de la gestion des affaires. Les modifications à l’environnement d’apprentissage en ligne sont documentées, ainsi que l’examen de l’incidence de ces modifications sur le processus d’apprentissage. L’étude montre aussi l’impact de l’engagement de l’apprenant avec les artefacts sur plusieurs itérations d’un cours dans un espace d’apprentissage en ligne doté de réseaux sociaux. Deux résultats importants ont émergé : 1. un espace d’apprentissage en ligne doté de réseaux sociaux peut offrir un endroit riche et soutenant pour l’enseignement et l’apprentissage; et 2. les étudiants dans cette étude sont favorables à l’inclusion d’une archive rassemblant les

Metabolic cold adaptation of polar fish based on measurements of aerobic oxygen consumption: fact or artefact? Artefact!

DEFF Research Database (Denmark)

Steffensen, John Fleng

2002-01-01

Whether metabolic cold adaptation in polar fish, based on measurements of aerobic standard metabolic rate, is a fact or an artefact has been a dispute since Holeton asked the question in 1974. So far polar fish had been considered to be metabolically cold adapted because they were reported to have...... a considerably elevated resting oxygen consumption, or standard metabolic rate, compared with oxygen consumption values of tropical or temperate fish extrapolated to similar low polar temperatures. Recent experiments on arctic and Antarctic fish, however, do not show elevated resting aerobic oxygen consumption...

Investigation of archaeological metal artefacts by laser-induced breakdown spectroscopy (LIBS)

Science.gov (United States)

Tankova, V.; Malcheva, G.; Blagoev, K.; Leshtakov, L.

2018-03-01

In this work, laser-induced breakdown spectroscopy was applied to determining the elemental composition of a set of ancient bronze artefacts dated from the Late Bronze Age and Early Iron Age (14th – 10th century BC). We used a Nd:YAG laser at 1064 nm with pulse duration of 10 ns and energy of 10 mJ and determined the elemental composition of the bronze alloy that was used in manufacturing the samples under study. The concentrations of tin and lead in the bulk of the examined materials was estimated after generating calibration curves for a set of four standard samples. The preliminary results of the analysis will provide information on the artefacts provenance and on the production process.

fMRI Artefact Rejection and Sleep Scoring Toolbox

Directory of Open Access Journals (Sweden)

Yves Leclercq

2011-01-01

Full Text Available We started writing the “fMRI artefact rejection and sleep scoring toolbox”, or “FAST”, to process our sleep EEG-fMRI data, that is, the simultaneous recording of electroencephalographic and functional magnetic resonance imaging data acquired while a subject is asleep. FAST tackles three crucial issues typical of this kind of data: (1 data manipulation (viewing, comparing, chunking, etc. of long continuous M/EEG recordings, (2 rejection of the fMRI-induced artefact in the EEG signal, and (3 manual sleep-scoring of the M/EEG recording. Currently, the toolbox can efficiently deal with these issues via a GUI, SPM8 batching system or hand-written script. The tools developed are, of course, also useful for other EEG applications, for example, involving simultaneous EEG-fMRI acquisition, continuous EEG eye-balling, and manipulation. Even though the toolbox was originally devised for EEG data, it will also gracefully handle MEG data without any problem. “FAST” is developed in Matlab as an add-on toolbox for SPM8 and, therefore, internally uses its SPM8-meeg data format. “FAST” is available for free, under the GNU-GPL.

Prospective ECG triggering reduces prosthetic heart valve-induced artefacts compared with retrospective ECG gating on 256-slice CT

NARCIS (Netherlands)

Symersky, P.; Habets, J.; Westers, P.; Mol, de B.A.J.M.; Prokop, M.; Budde, R.P.J.

2012-01-01

Objectives Multidetector computed tomography (MDCT) has diagnostic value for the evaluation of prosthetic heart valve (PHV) dysfunction but it is hampered by artefacts. We hypothesised that image acquisition using prospective triggering instead of retrospective gating would reduce artefacts related

On the feasibility of establishing the provenance of Australian Aboriginal artefacts using synchrotron radiation X-ray diffraction and proton-induced X-ray emission

International Nuclear Information System (INIS)

Creagh, D.C.; Kubik, M.E.; Sterns, M.

2007-01-01

Museums and galleries in Australia have extensive collections of Aboriginal artefacts in their custody. In particular, the National Museum of Australia and the National Gallery of Australia are custodians of works of very considerable significance, in both cultural and financial terms. Art fraud can occur, documentation relating to artefacts can be mislaid, or the artefacts can be incorrectly filed. Because of this, it has become essential to establish protocols for the objective determination of the provenance of artefacts through scientific tests. For the work reported here we are concerned with the comparison of very small quantities of materials, paint scrapings from artefacts. Scrapings from artefacts of unknown provenance are compared with those from artefacts of known provenance, and the database established using an extended set of analytical techniques by Kubik. We describe here our use of synchrotron radiation X-ray diffraction (SR-XRD) to determine the mineral phase compositions of very small amounts of pigment material (<50 μg), and the use of PIXE to give their atomic compositions to a threshold level of 1 ppm for similar masses of material

Influence of the in-plane artefact in chest tomosynthesis on pulmonary nodule size measurements

International Nuclear Information System (INIS)

Soederman, Christina; Allansdotter Johnsson, Aase; Vikgren, Jenny; Rossi Norrlund, Rauni; Molnar, David; Svalkvist, Angelica; Maansson, Lars Gunnar; Baath, Magnus

2016-01-01

The aim of the present study was to investigate how the in-plane artefact present in the scan direction around structures in tomosynthesis images should be managed when measuring the size of nodules in chest tomosynthesis images in order to achieve acceptable measurement accuracy. Data from measurements, performed by radiologists, of the longest diameter of artificial nodules inserted in chest tomosynthesis images were used. The association between the measurement error and the direction of the longest nodule diameter, relative to the scan direction, was evaluated using the Kendall rank correlation coefficient. All of the radiologists had chosen to not include the artefact in the measurements. Significant association between measurement error and the direction of the longest diameter was found for nodules larger than 12 mm, which indicates that, for these nodules, there is a risk of underestimating the nodule size if the in-plane artefact is omitted from manual diameter measurements. (authors)

Corrosion of archaeological iron artefacts compared to modern iron at the waterlogged site Nydam, Denmark

International Nuclear Information System (INIS)

Matthiesen, Henning; Gregory, David; Soerensen, Birgit; Hilbert, Rischel Lisbeth

2004-01-01

Since 1859 several archaeological excavations have been carried out in Nydam, Denmark revealing a wealth of military equipment sacrificed in the period 200 - 500 AD. During the 1990's more than 16000 artefacts of mainly wood and iron were excavated within an area of only 600 m 2 . Due to the volume of finds it was decided in 1997 to stop further excavations. At the same time a study program was initiated at the National Museum to evaluate the feasibility of preserving the remaining artefacts in situ for a prolonged period. The study comprises all materials present in Nydam, but this presentation focuses solely on the iron objects. A three-pronged approach has been used in the studies in Nydam: 1) Studies of the excavated artefacts, including the composition of corrosion products and a mapping of their exact state of preservation. 2) Use of modern iron samples placed in the soil for studies of weight loss, corrosion potential, electrochemical impedance spectroscopy and electrical resistivity. 3) Measurements of environmental parameters such as water level, redox potential, oxygen concentration, soil pH, and the concentration of a range of dissolved species in the pore water. This presentation shows some of the results obtained during the seven years of studies at the site. It is demonstrated how the three pronged approach is useful in understanding not only the current corrosion rate and threats against the artefacts but also the corrosion history, i.e. when were the deterioration patterns and corrosion products observed today actually formed. The corrosion rates for archaeological artefacts and modern analogues are compared and briefly discussed. (authors)

The role of movies in Norwegian textbooks. A study of film as artefact in religious education

Directory of Open Access Journals (Sweden)

Jon Magne Vestøl

2012-12-01

Full Text Available Drawing on perspectives on educational design, this article investigates the role of movies in Norwegian secondary school textbooks on religious education, including teachers’ handbooks and textbook websites. All passages containing references to films or movies have been included in the analysis. The distribution of references indicates that a film is an optional artefact and that movies are drawn mainly from a Western cinematic tradition and are related to topics such as Christianity and ethics. When textbook assignments introduce movies as artefacts mediating the understanding of religious issues, information about the message and the artistic role of the film seems to be downplayed. This indicates a need for reflection on how artefacts such as films are introduced into educational activity.

Quantifying metal artefact reduction using virtual monochromatic dual-layer detector spectral CT imaging in unilateral and bilateral total hip prostheses

Energy Technology Data Exchange (ETDEWEB)

Wellenberg, R.H.H., E-mail: r.h.wellenberg@amc.uva.nl [Department of Radiology, Academic Medical Centre, Amsterdam (Netherlands); Boomsma, M.F., E-mail: m.f.boomsma@isala.nl [Department of Radiology, Isala, Zwolle (Netherlands); Osch, J.A.C. van, E-mail: j.a.c.van.osch@isala.nl [Department of Radiology, Isala, Zwolle (Netherlands); Vlassenbroek, A., E-mail: alain.vlassenbroek@philips.com [Philips Medical Systems, Brussels (Belgium); Milles, J., E-mail: julien.milles@philips.com [Philips Medical Systems, Eindhoven (Netherlands); Edens, M.A., E-mail: m.a.edens@isala.nl [Department of Innovation and Science, Isala, Zwolle (Netherlands); Streekstra, G.J., E-mail: g.j.streekstra@amc.uva.nl [Department of Radiology, Academic Medical Centre, Amsterdam (Netherlands); Slump, C.H., E-mail: c.h.slump@utwente.nl [MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede (Netherlands); Maas, M., E-mail: m.maas@amc.uva.nl [Department of Radiology, Academic Medical Centre, Amsterdam (Netherlands)

2017-03-15

Highlights: • Dual-layer detector CT reduces metal artefacts at high monochromatic energies (keV). • 130 keV images were optimal based on quantitative analysis on CNRs. • Optimal keVs varied from 74 to 150 keV for different hip prostheses configurations. • The Titanium alloy resulted in less severe artefacts compared to the Cobalt alloy. • Severe metal artefacts, caused by extensive photon-starvation, were not reduced. - Abstract: Purpose: To quantify the impact of prosthesis material and design on the reduction of metal artefacts in total hip arthroplasties using virtual monochromatic dual-layer detector Spectral CT imaging. Methods: The water-filled total hip arthroplasty phantom was scanned on a novel 128-slice Philips IQon dual-layer detector Spectral CT scanner at 120-kVp and 140-kVp at a standard computed tomography dose index of 20.0 mGy. Several unilateral and bilateral hip prostheses consisting of different metal alloys were inserted and combined which were surrounded by 18 hydroxyapatite calcium carbonate pellets representing bone. Images were reconstructed with iterative reconstruction and analysed at monochromatic energies ranging from 40 to 200 keV. CT numbers in Hounsfield Units (HU), noise measured as the standard deviation in HU, signal-to-noise-ratios (SNRs) and contrast-to-noise-ratios (CNRs) were analysed within fixed regions-of-interests placed in and around the pellets. Results: In 70 and 74 keV virtual monochromatic images the CT numbers of the pellets were similar to 120-kVp and 140-kVp polychromatic results, therefore serving as reference. A separation into three categories of metal artefacts was made (no, mild/moderate and severe) where pellets were categorized based on HU deviations. At high keV values overall image contrast was reduced. For mild/moderate artefacts, the highest average CNRs were attained with virtual monochromatic 130 keV images, acquired at 140-kVp. Severe metal artefacts were not reduced. In 130 keV images

Quality Enhancement and Nerve Fibre Layer Artefacts Removal in Retina Fundus Images by Off Axis Imaging

Energy Technology Data Exchange (ETDEWEB)

Giancardo, Luca [ORNL; Meriaudeau, Fabrice [ORNL; Karnowski, Thomas Paul [ORNL; Li, Yaquin [University of Tennessee, Knoxville (UTK); Tobin Jr, Kenneth William [ORNL; Chaum, Edward [University of Tennessee, Knoxville (UTK)

2011-01-01

Retinal fundus images acquired with non-mydriatic digital fundus cameras are a versatile tool for the diagnosis of various retinal diseases. Because of the ease of use of newer camera models and their relative low cost, these cameras are employed worldwide by retina specialists to diagnose diabetic retinopathy and other degenerative diseases. Even with relative ease of use, the images produced by these systems sometimes suffer from reflectance artefacts mainly due to the nerve fibre layer (NFL) or other camera lens related reflections. We propose a technique that employs multiple fundus images acquired from the same patient to obtain a single higher quality image without these reflectance artefacts. The removal of bright artefacts, and particularly of NFL reflectance, can have great benefits for the reduction of false positives in the detection of retinal lesions such as exudate, drusens and cotton wool spots by automatic systems or manual inspection. If enough redundant information is provided by the multiple images, this technique also compensates for a suboptimal illumination. The fundus images are acquired in straightforward but unorthodox manner, i.e. the stare point of the patient is changed between each shot but the camera is kept fixed. Between each shot, the apparent shape and position of all the retinal structures that do not exhibit isotropic reflectance (e.g. bright artefacts) change. This physical effect is exploited by our algorithm in order to extract the pixels belonging to the inner layers of the retina, hence obtaining a single artefacts-free image.

Respiratory motion artefacts in dynamic liver MRI: a comparison using gadoxetate disodium and gadobutrol

Energy Technology Data Exchange (ETDEWEB)

Luetkens, Julian A.; Kupczyk, Patrick A.; Doerner, Jonas; Willinek, Winfried A.; Schild, Hans H.; Kukuk, Guido M. [University of Bonn, Department of Radiology, Bonn (Germany); Fimmers, Rolf [University of Bonn, Department of Medical Biometry, Informatics, and Epidemiology, Bonn (Germany)

2015-11-15

Our aim was to retrospectively evaluate the occurrence of respiratory motion artefacts in patients undergoing dynamic liver magnetic resonance (MR) either with gadoxetate disodium or gadobutrol. Two hundred and thirty liver MR studies (115 with gadobutrol, 115 with gadoxetate disodium) were analysed. Respiratory motion artefacts on dynamic 3D T1-weighted MR images (pre-contrast, arterial, venous, and late-dynamic phase) were assessed using a five-point rating scale. Severe motion was defined as a score ≥ 4. Mean motion scores were compared with the Mann-Whitney-U-test. The chi-squared-test was used for dichotomous comparisons. Mean motion scores for gadoxetate disodium and gadobutrol showed no relevant differences for each phase of the dynamic contrast series (pre-contrast: 1.85 ± 0.70 vs. 1.88 ± 0.57, arterial: 1.85 ± 0.81 vs. 1.87 ± 0.74, venous: 1.82 ± 0.67 vs. 1.74 ± 0.64, late-dynamic: 1.75 ± 0.62 vs. 1.79 ± 0.63; p = 0.469, 0.557, 0.382 and 0.843, respectively). Severe motion artefacts had a similar incidence using gadoxetate disodium and gadobutrol (11/460 [2.4 %] vs. 7/460 [1.5 %]; p = 0.341). Gadoxetate disodium is associated with equivalent motion scores compared to gadobutrol in dynamic liver MRI. In addition, both contrast agents demonstrated a comparable and acceptable rate of severe respiratory motion artefacts. (orig.)

Reconstruction artefacts in magnetic induction tomography due to patient's movement during data acquisition

International Nuclear Information System (INIS)

Gürsoy, D; Scharfetter, H

2009-01-01

Magnetic induction tomography (MIT) attempts to obtain the distribution of passive electrical properties inside the body. Eddy currents are induced in the body using an array of transmitter coils and the magnetic fields of these currents are measured by receiver coils. In clinical usage, the relative position of the coils to the body can change during data acquisition because of the expected/unexpected movements of the patient. Especially in respiration monitoring these movements will inevitably cause artefacts in the reconstructed images. In this paper, this effect was investigated for both state and frequency differential variants of MIT. It was found that a slight shift of the body in the transverse plane causes spurious perturbations on the surface. In reconstructions, this artefact on the surface propagates towards the centre in an oscillatory manner. It was observed that the movement can corrupt all the valuable information in state differential MIT, while frequency differential MIT seems more robust against movement effects. A filtering strategy is offered in order to decrease the movement artefacts in the images. To this end, monitoring of the patient's movement during data acquisition is required

The source of prehistoric obsidian artefacts from the Polynesian outlier of Taumako in the Solomon Islands

Energy Technology Data Exchange (ETDEWEB)

Leach, Foss [Otago Univ., Dunedin (New Zealand). Dept. of Anthropology

1985-01-01

Six obsidian artefacts from the Polynesian outlier of Taumako in the Solomon Islands dating to between 500 and 1000 B.C. were analysed for trace elements by the PIXE-PIGME method. Four are shown to derive from Vanuatu, but the remaining two artefacts do not match any of the known 66 sources in the Pacific region. Continuing difficulties with the methodology of Pacific obsidian sourcing are discussed. 14 refs; 2 tables.

Research into tin and arsenical copper artefacts using nuclear analytical techniques

International Nuclear Information System (INIS)

Grant, M.R.

1995-01-01

This study includes the chemical analysis, sourcing and historical metallurgy of tin and arsenical copper artefacts discovered at Rooiberg and elsewhere in the Northern Transvaal and at Great Zimbabwe. A complete chemical analysis method for tin and cassiterite is presented, based on INAA (instrumental neutron activation analysis) and supplemented by PIXE or AAS for elements such as lead, bismuth and niobium. This is apparently the first study in which tin artefacts were analysed by INAA without chemical processing of the samples. INAA and PIXE returned the same results when a homogenized tin alloy block was analysed, but the structure and distribution of hardhead phases appear to produce an iron quantification problem in ancient tin. Ores and slags were analysed for light matrix elements by XRF or PIXE and INAA for the heavy trace metals. 108 refs., 24 figs., 130 tabs

Artefacts induced by coiled intracranial aneurysms on 3.0-Tesla versus 1.5-Tesla MR angiography—An in vivo and in vitro study

Energy Technology Data Exchange (ETDEWEB)

Schaafsma, Joanna D., E-mail: j.d.schaafsma@umcutrecht.nl [Department of Neurology, Rudolf Magnus Institute of Neuroscience, University Medical Centre, PO Box 85500, 3508 GA Utrecht (Netherlands); Velthuis, Birgitta K., E-mail: b.k.velthuis@umcutrecht.nl [Imaging Division, University Medical Centre, PO Box 85500, 3508 GA Utrecht (Netherlands); Vincken, Koen L., E-mail: koen@isi.uu.nl [Image Sciences Institute, University Medical Centre, PO Box 85500, 3508 GA Utrecht (Netherlands); Kort, Gerard A.P. de, E-mail: g.a.p.dekort@umcutrecht.nl [Imaging Division, University Medical Centre, PO Box 85500, 3508 GA Utrecht (Netherlands); Rinkel, Gabriel J.E., E-mail: g.j.e.rinkel@umcutrecht.nl [Department of Neurology, Rudolf Magnus Institute of Neuroscience, University Medical Centre, PO Box 85500, 3508 GA Utrecht (Netherlands); Bartels, Lambertus W., E-mail: w.bartels@umcutrecht.nl [Image Sciences Institute, University Medical Centre, PO Box 85500, 3508 GA Utrecht (Netherlands)

2014-05-15

Objective: To compare metal-induced artefacts from coiled intracranial aneurysms on 3.0-Tesla and 1.5-Tesla magnetic resonance angiography (MRA), since concerns persist on artefact enlargement at 3.0 Tesla. Materials and methods: We scanned 19 patients (mean age 53; 16 women) with 20 saccular aneurysms treated with coils only, at 1.5 and 3.0 Tesla according to standard clinical 3D TOF-MRA protocols containing a shorter echo-time but weaker read-out gradient at 3.0 Tesla in addition to intra-arterial digital subtraction angiography (IA-DSA). Per modality two neuro-radiologists assessed the occlusion status, measured residual flow, and indicated whether coil artefacts disturbed this assessment on MRA. We assessed relative risks for disturbance by coil artefacts, weighted kappa's for agreement on occlusion levels, and we compared remnant sizes. For artefact measurements, a coil model was created and scanned with the same protocols followed by 2D MR scans with variation of echo-time and read-out gradient strength. Results: Coil artefacts disturbed assessments less frequently at 3.0 Tesla than at 1.5 Tesla (RR: 0.3; 95%CI: 0.1–0.8). On 3.0-Tesla MRA, remnants were larger than on 1.5-Tesla MRA (difference: 0.7 mm; 95%CI: 0.3–1.1) and larger than on IA-DSA (difference: 1.0 mm; 95%CI: 0.6–1.5) with similar agreement on occlusion levels with IA-DSA for both field strengths (κ 0.53; 95%CI: 0.23–0.84 for 1.5-Tesla MRA and IA-DSA; κ 0.47; 95%CI: 0.19–0.76 for 3.0-Tesla MRA and IA-DSA). Coil model artefacts were smaller at 3.0 Tesla than at 1.5 Tesla. The echo-time influenced artefact size more than the read-out gradient. Conclusions: Artefacts were not larger, but smaller at 3.0 Tesla because a shorter echo-time at 3.0 Tesla negated artefact enlargement. Despite smaller artefacts and larger remnants at 3.0 Tesla, occlusion levels were similar for both field strengths.

Artefacts induced by coiled intracranial aneurysms on 3.0-Tesla versus 1.5-Tesla MR angiography—An in vivo and in vitro study

International Nuclear Information System (INIS)

Schaafsma, Joanna D.; Velthuis, Birgitta K.; Vincken, Koen L.; Kort, Gerard A.P. de; Rinkel, Gabriel J.E.; Bartels, Lambertus W.

2014-01-01

Objective: To compare metal-induced artefacts from coiled intracranial aneurysms on 3.0-Tesla and 1.5-Tesla magnetic resonance angiography (MRA), since concerns persist on artefact enlargement at 3.0 Tesla. Materials and methods: We scanned 19 patients (mean age 53; 16 women) with 20 saccular aneurysms treated with coils only, at 1.5 and 3.0 Tesla according to standard clinical 3D TOF-MRA protocols containing a shorter echo-time but weaker read-out gradient at 3.0 Tesla in addition to intra-arterial digital subtraction angiography (IA-DSA). Per modality two neuro-radiologists assessed the occlusion status, measured residual flow, and indicated whether coil artefacts disturbed this assessment on MRA. We assessed relative risks for disturbance by coil artefacts, weighted kappa's for agreement on occlusion levels, and we compared remnant sizes. For artefact measurements, a coil model was created and scanned with the same protocols followed by 2D MR scans with variation of echo-time and read-out gradient strength. Results: Coil artefacts disturbed assessments less frequently at 3.0 Tesla than at 1.5 Tesla (RR: 0.3; 95%CI: 0.1–0.8). On 3.0-Tesla MRA, remnants were larger than on 1.5-Tesla MRA (difference: 0.7 mm; 95%CI: 0.3–1.1) and larger than on IA-DSA (difference: 1.0 mm; 95%CI: 0.6–1.5) with similar agreement on occlusion levels with IA-DSA for both field strengths (κ 0.53; 95%CI: 0.23–0.84 for 1.5-Tesla MRA and IA-DSA; κ 0.47; 95%CI: 0.19–0.76 for 3.0-Tesla MRA and IA-DSA). Coil model artefacts were smaller at 3.0 Tesla than at 1.5 Tesla. The echo-time influenced artefact size more than the read-out gradient. Conclusions: Artefacts were not larger, but smaller at 3.0 Tesla because a shorter echo-time at 3.0 Tesla negated artefact enlargement. Despite smaller artefacts and larger remnants at 3.0 Tesla, occlusion levels were similar for both field strengths

Artefacts induced by coiled intracranial aneurysms on 3.0-Tesla versus 1.5-Tesla MR angiography--An in vivo and in vitro study.

Science.gov (United States)

Schaafsma, Joanna D; Velthuis, Birgitta K; Vincken, Koen L; de Kort, Gerard A P; Rinkel, Gabriel J E; Bartels, Lambertus W

2014-05-01

To compare metal-induced artefacts from coiled intracranial aneurysms on 3.0-Tesla and 1.5-Tesla magnetic resonance angiography (MRA), since concerns persist on artefact enlargement at 3.0Tesla. We scanned 19 patients (mean age 53; 16 women) with 20 saccular aneurysms treated with coils only, at 1.5 and 3.0Tesla according to standard clinical 3D TOF-MRA protocols containing a shorter echo-time but weaker read-out gradient at 3.0Tesla in addition to intra-arterial digital subtraction angiography (IA-DSA). Per modality two neuro-radiologists assessed the occlusion status, measured residual flow, and indicated whether coil artefacts disturbed this assessment on MRA. We assessed relative risks for disturbance by coil artefacts, weighted kappa's for agreement on occlusion levels, and we compared remnant sizes. For artefact measurements, a coil model was created and scanned with the same protocols followed by 2D MR scans with variation of echo-time and read-out gradient strength. Coil artefacts disturbed assessments less frequently at 3.0Tesla than at 1.5Tesla (RR: 0.3; 95%CI: 0.1-0.8). On 3.0-Tesla MRA, remnants were larger than on 1.5-Tesla MRA (difference: 0.7mm; 95%CI: 0.3-1.1) and larger than on IA-DSA (difference: 1.0mm; 95%CI: 0.6-1.5) with similar agreement on occlusion levels with IA-DSA for both field strengths (κ 0.53; 95%CI: 0.23-0.84 for 1.5-Tesla MRA and IA-DSA; κ 0.47; 95%CI: 0.19-0.76 for 3.0-Tesla MRA and IA-DSA). Coil model artefacts were smaller at 3.0Tesla than at 1.5Tesla. The echo-time influenced artefact size more than the read-out gradient. Artefacts were not larger, but smaller at 3.0Tesla because a shorter echo-time at 3.0Tesla negated artefact enlargement. Despite smaller artefacts and larger remnants at 3.0Tesla, occlusion levels were similar for both field strengths. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

A previously undescribed organic residue sheds light on heat treatment in the Middle Stone Age.

Science.gov (United States)

Schmidt, Patrick; Porraz, Guillaume; Bellot-Gurlet, Ludovic; February, Edmund; Ligouis, Bertrand; Paris, Céline; Texier, Pierre-Jean; Parkington, John E; Miller, Christopher E; Nickel, Klaus G; Conard, Nicholas J

2015-08-01

South Africa has in recent years gained increasing importance for our understanding of the evolution of 'modern human behaviour' during the Middle Stone Age (MSA). A key element in the suite of behaviours linked with modern humans is heat treatment of materials such as ochre for ritual purposes and stone prior to tool production. Until now, there has been no direct archaeological evidence for the exact procedure used in the heat treatment of silcrete. Through the analysis of heat-treated artefacts from the Howiesons Poort of Diepkloof Rock Shelter, we identified a hitherto unknown type of organic residue - a tempering-residue - that sheds light on the processes used for heat treatment in the MSA. This black film on the silcrete surface is an organic tar that contains microscopic fragments of charcoal and formed as a residue during the direct contact of the artefacts with hot embers of green wood. Our results suggest that heat treatment of silcrete was conducted directly using an open fire, similar to those likely used for cooking. These findings add to the discussion about the complexity of MSA behaviour and appear to contradict previous studies that had suggested that heat treatment of silcrete was a complex (i.e., requiring a large number of steps for its realization) and resource-consuming procedure. Copyright © 2015 Elsevier Ltd. All rights reserved.

Computed Tomography Imaging of a Hip Prosthesis Using Iterative Model-Based Reconstruction and Orthopaedic Metal Artefact Reduction: A Quantitative Analysis.

Science.gov (United States)

Wellenberg, Ruud H H; Boomsma, Martijn F; van Osch, Jochen A C; Vlassenbroek, Alain; Milles, Julien; Edens, Mireille A; Streekstra, Geert J; Slump, Cornelis H; Maas, Mario

To quantify the combined use of iterative model-based reconstruction (IMR) and orthopaedic metal artefact reduction (O-MAR) in reducing metal artefacts and improving image quality in a total hip arthroplasty phantom. Scans acquired at several dose levels and kVps were reconstructed with filtered back-projection (FBP), iterative reconstruction (iDose) and IMR, with and without O-MAR. Computed tomography (CT) numbers, noise levels, signal-to-noise-ratios and contrast-to-noise-ratios were analysed. Iterative model-based reconstruction results in overall improved image quality compared to iDose and FBP (P < 0.001). Orthopaedic metal artefact reduction is most effective in reducing severe metal artefacts improving CT number accuracy by 50%, 60%, and 63% (P < 0.05) and reducing noise by 1%, 62%, and 85% (P < 0.001) whereas improving signal-to-noise-ratios by 27%, 47%, and 46% (P < 0.001) and contrast-to-noise-ratios by 16%, 25%, and 19% (P < 0.001) with FBP, iDose, and IMR, respectively. The combined use of IMR and O-MAR strongly improves overall image quality and strongly reduces metal artefacts in the CT imaging of a total hip arthroplasty phantom.

Evidence of metallic plating on archaeological artefacts by voltammetry of microparticles

Czech Academy of Sciences Publication Activity Database

Ottenwelter, Estelle; Costa, V.

2015-01-01

Roč. 57, č. 3 (2015), s. 497-504 ISSN 0003-813X Institutional support: RVO:67985912 Keywords : metallic plating * voltammetry of microparticles * non-invasive analysis * medieval period * archaeological artefacts Subject RIV: AC - Archeology, Anthropology, Ethnology Impact factor: 1.364, year: 2015

A simple solution for reducing artefacts due to conductive and dielectric effects in clinical magnetic resonance imaging at 3 T

International Nuclear Information System (INIS)

Sreenivas, M.; Lowry, M.; Gibbs, P.; Pickles, M.; Turnbull, L.W.

2007-01-01

The quality of imaging obtained at high magnetic field strengths can be degraded by various artefacts due to conductive and dielectric effects, which leads to loss of signal. Various methods have been described and used to improve the quality of the image affected by such artefacts. In this article, we describe the construction and use of a simple solution that can be used to diminish artefacts due to conductive and dielectric effects in clinical imaging at 3 T field strength and thereby improve the diagnostic quality of the images obtained

A simple solution for reducing artefacts due to conductive and dielectric effects in clinical magnetic resonance imaging at 3 T

Energy Technology Data Exchange (ETDEWEB)

Sreenivas, M. [Department of Radiology (Yorkshire Deanery-East), Hull Royal Infirmary, Anlaby Road, Hull HU3 2JZ (United Kingdom)]. E-mail: aprilsreenivas@hotmail.com; Lowry, M. [Centre for Magnetic Resonance Investigations, University of Hull, Hull Royal Infirmary, Anlaby Road, 1PR, Hull HU3 2JZ (United Kingdom); Gibbs, P. [Centre for Magnetic Resonance Investigations, University of Hull, Hull Royal Infirmary, Anlaby Road, 1PR, Hull HU3 2JZ (United Kingdom); Pickles, M. [Centre for Magnetic Resonance Investigations, University of Hull, Hull Royal Infirmary, Anlaby Road, 1PR, Hull HU3 2JZ (United Kingdom); Turnbull, L.W. [Centre for Magnetic Resonance Investigations, University of Hull, Hull Royal Infirmary, Anlaby Road, 1PR, Hull HU3 2JZ (United Kingdom)

2007-04-15

The quality of imaging obtained at high magnetic field strengths can be degraded by various artefacts due to conductive and dielectric effects, which leads to loss of signal. Various methods have been described and used to improve the quality of the image affected by such artefacts. In this article, we describe the construction and use of a simple solution that can be used to diminish artefacts due to conductive and dielectric effects in clinical imaging at 3 T field strength and thereby improve the diagnostic quality of the images obtained.

Suppression of high-density artefacts in x-ray CT images using temporal digital subtraction with application to cryotherapy

Energy Technology Data Exchange (ETDEWEB)

Baissalov, R.; Sandison, G.A.; Rewcastle, J.C. [Department of Medical Physics, Tom Baker Cancer Center, Calgary, Canada, T2N 4N2 2 Department of Physics and Astronomy, University of Calgary, Calgary T2N 2N4 (Canada); Donnelly, B.J. [Department of Surgery, Tom Baker Cancer Center, Calgary, Canada, T2N 4N2 4 Department of Surgery, Foothills Hospital, Calgary T2N 2T7 (Canada); Saliken, J.C. [Department of Surgery, Tom Baker Cancer Center, Calgary T2N 4N2 (Canada); Department of Diagnostic Imaging, Foothills Hospital, Calgary T2N 2T7 (Canada); McKinnon, J.G. [Department of Surgery, Foothills Hospital, Calgary T2N 2T7 (Canada); Muldrew, K. [Department of Surgery, Faculty of Medicine, University of Calgary, Calgary T2N 2T7 (Canada)

2000-05-01

Image guidance in cryotherapy is usually performed using ultrasound. Although not currently in routine clinical use, x-ray CT imaging is an alternative means of guidance that can display the full 3D structure of the iceball, including frozen and unfrozen regions. However, the quality of x-ray CT images is compromised by the presence of high-density streak artefacts. To suppress these artefacts we applied temporal digital subtraction (TDS). This TDS method has the added advantage of improving the grey-scale contrast between frozen and unfrozen tissue in the CT images. Two sets of CT images were taken of a phantom material, cryoprobes and a urethral warmer (UW) before and during the cryoprobe freeze cycle. The high-density artefacts persisted in both image sets. TDS was performed on these two image sets using the corresponding mask image of unfrozen material and the same geometrical configuration of the cryoprobes and the UW. The resultant difference image had a significantly reduced artefact content. Thus TDS can be used to significantly suppress or eliminate high-density CT streak artefacts without reducing the metallic content of the cryoprobes. In vivo study needs to be conducted to establish the utility of this TDS procedure for CT assisted prostate or liver cryotherapy. Applying TDS in x-ray CT guided cryotherapy will facilitate estimation of the number and location of all frozen and unfrozen regions, potentially making cryotherapy safer and less operator dependent. (author)

Suppression of high-density artefacts in x-ray CT images using temporal digital subtraction with application to cryotherapy

International Nuclear Information System (INIS)

Baissalov, R.; Sandison, G.A.; Rewcastle, J.C.; Donnelly, B.J.; Saliken, J.C.; McKinnon, J.G.; Muldrew, K.

2000-01-01

Image guidance in cryotherapy is usually performed using ultrasound. Although not currently in routine clinical use, x-ray CT imaging is an alternative means of guidance that can display the full 3D structure of the iceball, including frozen and unfrozen regions. However, the quality of x-ray CT images is compromised by the presence of high-density streak artefacts. To suppress these artefacts we applied temporal digital subtraction (TDS). This TDS method has the added advantage of improving the grey-scale contrast between frozen and unfrozen tissue in the CT images. Two sets of CT images were taken of a phantom material, cryoprobes and a urethral warmer (UW) before and during the cryoprobe freeze cycle. The high-density artefacts persisted in both image sets. TDS was performed on these two image sets using the corresponding mask image of unfrozen material and the same geometrical configuration of the cryoprobes and the UW. The resultant difference image had a significantly reduced artefact content. Thus TDS can be used to significantly suppress or eliminate high-density CT streak artefacts without reducing the metallic content of the cryoprobes. In vivo study needs to be conducted to establish the utility of this TDS procedure for CT assisted prostate or liver cryotherapy. Applying TDS in x-ray CT guided cryotherapy will facilitate estimation of the number and location of all frozen and unfrozen regions, potentially making cryotherapy safer and less operator dependent. (author)

Clinical learning environments: place, artefacts and rhythm.

Science.gov (United States)

Sheehan, Dale; Jowsey, Tanisha; Parwaiz, Mariam; Birch, Mark; Seaton, Philippa; Shaw, Susan; Duggan, Alison; Wilkinson, Tim

2017-10-01

Health care practitioners learn through experience in clinical environments in which supervision is a key component, but how that learning occurs outside the supervision relationship remains largely unknown. This study explores the environmental factors that inform and support workplace learning within a clinical environment. An observational study drawing on ethnographic methods was undertaken in a general medicine ward. Observers paid attention to interactions among staff members that involved potential teaching and learning moments that occurred and were visible in the course of routine work. General purpose thematic analysis of field notes was undertaken. A total of 376 observations were undertaken and documented. The findings suggest that place (location of interaction), rhythm (regularity of activities occurring in the ward) and artefacts (objects and equipment) were strong influences on the interactions and exchanges that occurred. Each of these themes had inherent tensions that could promote or inhibit engagement and therefore learning opportunities. Although many learning opportunities were available, not all were taken up or recognised by the participants. We describe and make explicit how the natural environment of a medical ward and flow of work through patient care contribute to the learning architecture, and how this creates or inhibits opportunities for learning. Awareness of learning opportunities was often tacit and not explicit for either supervisor or learner. We identify strategies through which tensions inherent within space, artefacts and the rhythms of work can be resolved and learning opportunities maximised. © 2017 John Wiley & Sons Ltd and The Association for the Study of Medical Education.

The use of radiation in the study of cultural heritage artefacts

International Nuclear Information System (INIS)

Creagh, Dudley; Otieno-Alego, Vincent; Treasure, Alana; Kubik, Maria; Hallam, David

2017-01-01

Patrons of art galleries and museums, tourists visiting historic buildings, and sightseers viewing archaeological sites are generally unaware of the extent to which science and technology has contributed to the value of what they see. Many countries rely on cultural tourism to generate national wealth. The use of radiation of many kinds to assist in the conservation/restoration of cultural heritage artefacts is described in this paper. In particular, the paper will describe studies of the pigments used in historic Australian Indigenous art, the degradation of manuscripts written using iron-gall inks, the protection of statues against corrosion and the selection of lubricants for use in old machinery. - Highlights: • We describe a diverse range of techniques used to study cultural heritage artefacts. • IR X-ray and particle beam techniques were used to study: • The structure and composition of Australian Indigenous bark paintings. • The effects of iron-gall inks on parchment. • The results of corrosion and corrosion protection in machinery and vehicles.

Lab-based x-ray tomography of a cochlear implant using energy discriminating detectors for metal artefact reduction

Science.gov (United States)

Yokhana, Viona S. K.; Arhatari, Benedicta D.; Gureyev, Timur E.; Abbey, Brian

2018-01-01

X-ray computed tomography (XCT) is an important clinical diagnostic tool which is also used in a range of biological imaging applications in research. The increasing prevalence of metallic implants in medical and dental radiography and tomography has driven the demand for new approaches to solving the issue of metal artefacts in XCT. Metal artefacts occur when a highly absorbing material is imaged which is in boundary contact with one or more weakly absorbing components, such as soft-tissue. The resulting `streaking' in the reconstructed images creates significant challenges for X-ray analysis due to the non-linear dependence on the absorption properties of the sample. In this paper we introduce a new approach to removing metal artefacts which exploits the capabilities of the recently available, photon-counting PiXirad detector. Our approach works for standard lab-based polychromatic X-ray tubes and does not rely on any postprocessing of the data. The method is demonstrated using both simulated data from a test phantom and experimental data collected from a cochlear implant. The results show that by combining the individual images, which are simultaneously generated for each different energy threshold, artefact -free segmentation of the implant from the surrounding biological tissue is achieved.

Evaluation of a prototype correction algorithm to reduce metal artefacts in flat detector computed tomography of scaphoid fixation screws.

Science.gov (United States)

Filli, Lukas; Marcon, Magda; Scholz, Bernhard; Calcagni, Maurizio; Finkenstädt, Tim; Andreisek, Gustav; Guggenberger, Roman

2014-12-01

The aim of this study was to evaluate a prototype correction algorithm to reduce metal artefacts in flat detector computed tomography (FDCT) of scaphoid fixation screws. FDCT has gained interest in imaging small anatomic structures of the appendicular skeleton. Angiographic C-arm systems with flat detectors allow fluoroscopy and FDCT imaging in a one-stop procedure emphasizing their role as an ideal intraoperative imaging tool. However, FDCT imaging can be significantly impaired by artefacts induced by fixation screws. Following ethical board approval, commercially available scaphoid fixation screws were inserted into six cadaveric specimens in order to fix artificially induced scaphoid fractures. FDCT images corrected with the algorithm were compared to uncorrected images both quantitatively and qualitatively by two independent radiologists in terms of artefacts, screw contour, fracture line visibility, bone visibility, and soft tissue definition. Normal distribution of variables was evaluated using the Kolmogorov-Smirnov test. In case of normal distribution, quantitative variables were compared using paired Student's t tests. The Wilcoxon signed-rank test was used for quantitative variables without normal distribution and all qualitative variables. A p value of < 0.05 was considered to indicate statistically significant differences. Metal artefacts were significantly reduced by the correction algorithm (p < 0.001), and the fracture line was more clearly defined (p < 0.01). The inter-observer reliability was "almost perfect" (intra-class correlation coefficient 0.85, p < 0.001). The prototype correction algorithm in FDCT for metal artefacts induced by scaphoid fixation screws may facilitate intra- and postoperative follow-up imaging. Flat detector computed tomography (FDCT) is a helpful imaging tool for scaphoid fixation. The correction algorithm significantly reduces artefacts in FDCT induced by scaphoid fixation screws. This may facilitate intra

Are osseous artefacts a window to perishable material culture? Implications of an unusually complex bone tool from the Late Pleistocene of East Timor.

Science.gov (United States)

O'Connor, S; Robertson, G; Aplin, K P

2014-02-01

We report the discovery of an unusually complex and regionally unique bone artefact in a Late Pleistocene archaeological assemblage (c. 35 ka [thousands of years ago]) from the site of Matja Kuru 2 on the island of Timor, in Wallacea. The artefact is interpreted as the broken butt of a formerly hafted projectile point, and it preserves evidence of a complex hafting mechanism including insertion into a shaped or split shaft, a complex pattern of binding including lateral stabilization of the cordage within a bilateral series of notches, and the application of mastic at several stages in the hafting process. The artefact provides the earliest direct evidence for the use of this combination of hafting technologies in the wider region of Southeast Asia, Wallacea, Melanesia and Australasia, and is morphologically unparallelled in deposits of any age. By contrast, it bears a close morphological resemblance to certain bone artefacts from the Middle Stone Age of Africa and South Asia. Examination of ethnographic projectile technology from the region of Melanesia and Australasia shows that all of the technological elements observed in the Matja Kuru 2 artefact were in use historically in the region, including the unusual feature of bilateral notching to stabilize a hafted point. This artefact challenges the notion that complex bone-working and hafting technologies were a relatively late innovation in this part of the world. Moreover, its regional uniqueness encourages us to abandon the perception of bone artefacts as a discrete class of material culture, and to adopt a new interpretative framework in which they are treated as manifestations of a more general class of artefacts that more typically were produced on perishable raw materials including wood. Crown Copyright © 2014. Published by Elsevier Ltd. All rights reserved.

Planning Uncertainty: Creating an Artefact Density Index for North Yorkshire, England

Directory of Open Access Journals (Sweden)

Nick Boldrini

2007-04-01

Full Text Available Portable antiquities (sometimes known as small finds or chance finds are often recorded within most Historic Environment Records to a spurious level of precision. For example, finds located only within a parish, or general area, are often mapped within GIS systems to exact points. Similarly, finds known only to the nearest kilometre square are usually mapped in the bottom left-hand corner of the square in GIS. While such mappings can be taken into account to some extent when trying to assess the archaeological potential of an area, the degree to which the records may give distorted views of the archaeological potential of an area may not be fully appreciated. This may mean that the full archaeological impacts of development may not be taken into account during development control decision making. This article looks at an alternative method for mapping such finds in order to produce an Artefact Density Index for areas, which more usefully reflects the pattern of activities across the landscape. The Artefact Density Index (ADI was divided to reflect broad archaeological periods (e.g. Roman, medieval etc., as well as broad artefact types (e.g. weapons, tools etc.. The ADI was based on combining weighted values for finds types, with the weight reflecting the precision of the location of the finds (i.e. finds recorded only at parish level will be given less weight than those recorded more precisely. An ADI was developed for a sub-area of the North Yorkshire County Council HER area, and also incorporated data from the Portable Antiquities scheme as a case study for the project.

Implications of Artefacts Reduction in the Planning CT Originating from Implanted Fiducial Markers

International Nuclear Information System (INIS)

Kassim, Iskandar; Joosten, Hans; Barnhoorn, Jaco C.; Heijmen, Ben J.M.; Dirkx, Maarten L.P.

2011-01-01

The efficacy of metal artefact reduction (MAR) software to suppress artefacts in reconstructed computed tomography (CT) images originating from small metal objects, like tumor markers and surgical clips, was evaluated. In addition, possible implications of using digital reconstructed radiographs (DRRs), based on the MAR CT images, for setup verification were analyzed. A phantom and 15 patients with different tumor sites and implanted markers were imaged with a multislice CT scanner. The raw image data was reconstructed both with the clinically used filtered-backprojection (FBP) and with the MAR software. Using the MAR software, improvements in image quality were often observed in CT slices with markers or clips. Especially when several markers were located near to each other, fewer streak artefacts were observed than with the FBP algorithm. In addition, the shape and size of markers could be identified more accurately, reducing the contoured marker volumes by a factor of 2. For the phantom study, the CT numbers measured near to the markers corresponded more closely to the expected values. However, the MAR images were slightly more smoothed compared with the images reconstructed with FBP. For 8 prostate cancer patients in this study, the interobserver variation in 3D marker definition was similar (<0.4 mm) when using DRRs based on either FBP or MAR CT scans. Automatic marker matches also showed a similar success rate. However, differences in automatic match results up to 1 mm, caused by differences in the marker definition, were observed, which turned out to be (borderline) statistically significant (p = 0.06) for 2 patients. In conclusion, the MAR software might improve image quality by suppressing metal artefacts, probably allowing for a more reliable delineation of structures. When implanted markers or clips are used for setup verification, the accuracy may slightly be improved as well, which is relevant when using very tight clinical target volume (CTV) to

fiReproxies: A computational model providing insight into heat-affected archaeological lithic assemblages.

Science.gov (United States)

Sorensen, Andrew C; Scherjon, Fulco

2018-01-01

Evidence for fire use becomes increasingly sparse the further back in time one looks. This is especially true for Palaeolithic assemblages. Primary evidence of fire use in the form of hearth features tends to give way to clusters or sparse scatters of more durable heated stone fragments. In the absence of intact fireplaces, these thermally altered lithic remains have been used as a proxy for discerning relative degrees of fire use between archaeological layers and deposits. While previous experimental studies have demonstrated the physical effects of heat on stony artefacts, the mechanisms influencing the proportion of fire proxy evidence within archaeological layers remain understudied. This fundamental study is the first to apply a computer-based model (fiReproxies) in an attempt to simulate and quantify the complex interplay of factors that ultimately determine when and in what proportions lithic artefacts are heated by (anthropogenic) fires. As an illustrative example, we apply our model to two hypothetical archaeological layers that reflect glacial and interglacial conditions during the late Middle Palaeolithic within a generic simulated cave site to demonstrate how different environmental, behavioural and depositional factors like site surface area, sedimentation rate, occupation frequency, and fire size and intensity can, independently or together, significantly influence the visibility of archaeological fire signals.

Angiographic and artefact-free computed tomography imaging of experimental aneurysms embolised with hydrogel filaments

Energy Technology Data Exchange (ETDEWEB)

McCoy, Mark R. [Paracelsus Medical University, Department of Radiology and Magnetic Resonance Tomography, Christian Doppler Clinic, Salzburg (Austria); Cruise, Gregory M. [MicroVention Terumo, Aliso Viejo, CA (United States); Killer, Monika [Paracelsus Medical University, Department of Neurology/Neuroscience Institute, Christian Doppler Clinic, Salzburg (Austria)

2010-04-15

We compared experimental rabbit carotid bifurcation aneurysms embolised with platinum coils or hydrogel filaments by using digital subtraction angiography (DSA) and computed tomography angiography (CTA). Embolisation was performed using platinum coils (n = 2), hydrogel filaments loaded with iodine (n = 3) and hydrogel filaments loaded with barium sulphate (n = 3). In one case, a stent was deployed in the parent vessel to determine the effect of hydrogel filaments on stent visualisation. DSA evaluations occurred immediately post-treatment. CTA evaluations occurred at 0-13 weeks post-treatment. The DSA and CTA images were evaluated for the lack of artefacts and the visibilities of the embolic mass, individual coils and residual flow in the aneurysm sac and neck. The DSA results were largely concordant among the three groups. The embolic masses were readily evident with some individual coils being distinguished. In the aneurysms embolised with hydrogel filaments, visualisation of the individual coils, residual flow and stent with minor or no artefacts was possible using CTA. On the other hand, the beam hardening artefacts precluded analysis of aneurysms embolised with platinum coils. CTA-compatible embolic devices could have wide applications in diverse locations throughout the vasculature, particularly in combination with stents or stent grafts. (orig.)

Risk Identification in a Smart Monitoring System Used to Preserve Artefacts Based on Textile Materials

Science.gov (United States)

Diaconescu, V. D.; Scripcariu, L.; Mătăsaru, P. D.; Diaconescu, M. R.; Ignat, C. A.

2018-06-01

Exhibited textile-materials-based artefacts can be affected by the environmental conditions. A smart monitoring system that commands an adaptive automatic environment control system is proposed for indoor exhibition spaces containing various textile artefacts. All exhibited objects are monitored by many multi-sensor nodes containing temperature, relative humidity and light sensors. Data collected periodically from the entire sensor network is stored in a database and statistically processed in order to identify and classify the environment risk. Risk consequences are analyzed depending on the risk class and the smart system commands different control measures in order to stabilize the indoor environment conditions to the recommended values and prevent material degradation.

Evaluation of a prototype correction algorithm to reduce metal artefacts in flat detector computed tomography of scaphoid fixation screws

Energy Technology Data Exchange (ETDEWEB)

Filli, Lukas; Finkenstaedt, Tim; Andreisek, Gustav; Guggenberger, Roman [University Hospital of Zurich, Department of Diagnostic and Interventional Radiology, Zurich (Switzerland); Marcon, Magda [University Hospital of Zurich, Department of Diagnostic and Interventional Radiology, Zurich (Switzerland); University of Udine, Institute of Diagnostic Radiology, Department of Medical and Biological Sciences, Udine (Italy); Scholz, Bernhard [Imaging and Therapy Division, Siemens AG, Healthcare Sector, Forchheim (Germany); Calcagni, Maurizio [University Hospital of Zurich, Division of Plastic Surgery and Hand Surgery, Zurich (Switzerland)

2014-12-15

The aim of this study was to evaluate a prototype correction algorithm to reduce metal artefacts in flat detector computed tomography (FDCT) of scaphoid fixation screws. FDCT has gained interest in imaging small anatomic structures of the appendicular skeleton. Angiographic C-arm systems with flat detectors allow fluoroscopy and FDCT imaging in a one-stop procedure emphasizing their role as an ideal intraoperative imaging tool. However, FDCT imaging can be significantly impaired by artefacts induced by fixation screws. Following ethical board approval, commercially available scaphoid fixation screws were inserted into six cadaveric specimens in order to fix artificially induced scaphoid fractures. FDCT images corrected with the algorithm were compared to uncorrected images both quantitatively and qualitatively by two independent radiologists in terms of artefacts, screw contour, fracture line visibility, bone visibility, and soft tissue definition. Normal distribution of variables was evaluated using the Kolmogorov-Smirnov test. In case of normal distribution, quantitative variables were compared using paired Student's t tests. The Wilcoxon signed-rank test was used for quantitative variables without normal distribution and all qualitative variables. A p value of < 0.05 was considered to indicate statistically significant differences. Metal artefacts were significantly reduced by the correction algorithm (p < 0.001), and the fracture line was more clearly defined (p < 0.01). The inter-observer reliability was ''almost perfect'' (intra-class correlation coefficient 0.85, p < 0.001). The prototype correction algorithm in FDCT for metal artefacts induced by scaphoid fixation screws may facilitate intra- and postoperative follow-up imaging. (orig.)

Evaluation of a prototype correction algorithm to reduce metal artefacts in flat detector computed tomography of scaphoid fixation screws

International Nuclear Information System (INIS)

Filli, Lukas; Finkenstaedt, Tim; Andreisek, Gustav; Guggenberger, Roman; Marcon, Magda; Scholz, Bernhard; Calcagni, Maurizio

2014-01-01

The aim of this study was to evaluate a prototype correction algorithm to reduce metal artefacts in flat detector computed tomography (FDCT) of scaphoid fixation screws. FDCT has gained interest in imaging small anatomic structures of the appendicular skeleton. Angiographic C-arm systems with flat detectors allow fluoroscopy and FDCT imaging in a one-stop procedure emphasizing their role as an ideal intraoperative imaging tool. However, FDCT imaging can be significantly impaired by artefacts induced by fixation screws. Following ethical board approval, commercially available scaphoid fixation screws were inserted into six cadaveric specimens in order to fix artificially induced scaphoid fractures. FDCT images corrected with the algorithm were compared to uncorrected images both quantitatively and qualitatively by two independent radiologists in terms of artefacts, screw contour, fracture line visibility, bone visibility, and soft tissue definition. Normal distribution of variables was evaluated using the Kolmogorov-Smirnov test. In case of normal distribution, quantitative variables were compared using paired Student's t tests. The Wilcoxon signed-rank test was used for quantitative variables without normal distribution and all qualitative variables. A p value of < 0.05 was considered to indicate statistically significant differences. Metal artefacts were significantly reduced by the correction algorithm (p < 0.001), and the fracture line was more clearly defined (p < 0.01). The inter-observer reliability was ''almost perfect'' (intra-class correlation coefficient 0.85, p < 0.001). The prototype correction algorithm in FDCT for metal artefacts induced by scaphoid fixation screws may facilitate intra- and postoperative follow-up imaging. (orig.)

PET/CT Atlas on Quality Control and Image Artefacts

International Nuclear Information System (INIS)

2014-01-01

Combined positron emission tomography (PET)/computed tomography (CT) imaging has become a routine procedure in diagnostic radiology and nuclear medicine. The clinical review of both PET and PET/CT images requires a thorough understanding of the basics of image formation as well as an appreciation of variations of inter-patient and intra-patient image appearance. Such variations may be caused by variations in tracer accumulation and metabolism, and, perhaps more importantly, by image artefacts related to methodological pitfalls of the two modalities. This atlas on quality control (QC) and PET/CT artefacts provides guidance on typical image distortions in clinical PET/CT usage scenarios. A number of cases are presented to provide nuclear medicine and radiology professionals with an assortment of examples of possible image distortions and errors in order to support the correct interpretation of images. About 70 typical PET and PET/CT cases, comprised of image sets and cases, have been collected in this book, and all have been catalogued and have explanations as to the causes of and solutions to each individual image problem. This atlas is intended to be used as a guide on how to take proper QC measures, on performing situation and problem analysis, and on problem prevention. This book will be especially useful to medical physicists, physicians, technologists and service engineers in the clinical field

Evaluation of the impact of dental artefacts on intensity-modulated radiotherapy planning for the head and neck

International Nuclear Information System (INIS)

Webster, Gareth J.; Rowbottom, Carl G.; Mackay, Ranald I.

2009-01-01

Background and purpose: High density materials create severe artefacts in the computed tomography (CT) scans used for radiotherapy dose calculations. Increased use of intensity-modulated radiotherapy (IMRT) to treat oropharyngeal cancers raises concerns over the accuracy of the resulting dose calculation. This work quantifies their impact and evaluates a simple corrective technique. Materials and methods: Fifteen oropharyngeal patients with severe artefacts were retrospectively planned with IMRT using two different CT/density look-up tables. Each plan was recalculated using a corrected CT dataset to evaluate the dose distribution delivered to the patient. Plan quality in the absence of dental artefacts was similarly assessed. A range of dosimetric and radiobiological parameters were compared pre- and post-correction. Results: Plans using a standard CT/density look-up table (density ≤1.8 g/cm 3 ) revealed inconsistent inter-patient errors, mostly within clinical acceptance, although potentially significantly reducing target coverage for individual patients. Using an extended CT/density look-up table (density ≤10.0 g/cm 3 ) greatly reduced the errors for 13/15 patients. In 2/15 patients with residual errors the CTV extended into the severely affected region and could be corrected by applying a simple manual correction. Conclusions: Use of an extended CT/density look-up table together with a simple manual bulk density correction reduces the impact of dental artefacts on head and neck IMRT planning to acceptable levels.

Evaluation of efficacy of metal artefact reduction technique using contrast media in Computed Tomography

Science.gov (United States)

Yusob, Diana; Zukhi, Jihan; Aziz Tajuddin, Abd; Zainon, Rafidah

2017-05-01

The aim of this study was to evaluate the efficacy of metal artefact reduction using contrasts media in Computed Tomography (CT) imaging. A water-based abdomen phantom of diameter 32 cm (adult body size) was fabricated using polymethyl methacrylate (PMMA) material. Three different contrast agents (iodine, barium and gadolinium) were filled in small PMMA tubes and placed inside a water-based PMMA adult abdomen phantom. The orthopedic metal screw was placed in each small PMMA tube separately. These two types of orthopedic metal screw (stainless steel and titanium alloy) were scanned separately. The orthopedic metal crews were scanned with single-energy CT at 120 kV and dual-energy CT at fast kV-switching between 80 kV and 140 kV. The scan modes were set automatically using the current modulation care4Dose setting and the scans were set at different pitch and slice thickness. The use of the contrast media technique on orthopedic metal screws were optimised by using pitch = 0.60 mm, and slice thickness = 5.0 mm. The use contrast media can reduce the metal streaking artefacts on CT image, enhance the CT images surrounding the implants, and it has potential use in improving diagnostic performance in patients with severe metallic artefacts. These results are valuable for imaging protocol optimisation in clinical applications.

The origin of emeralds embedded in archaeological artefacts in Slovenia

Directory of Open Access Journals (Sweden)

Albina Kržič

2013-06-01

Full Text Available Roman gold jewellery, which was excavated in Ptuj (Poetovio and consists of a necklace, earrings and a braceletwith embedded emeralds, is part of the Slovenian archaeological artefacts collections. Crystallographic characteristics,inclusions, luminous phenomena and geological characteristics were determined in order to establish theorigin of the emeralds. Chemical composition of the emeralds was determined non-destructively using the methodsof proton-induced X-rays and gamma rays (PIXE/PIGE. The results were compared with reference emeraldsfrom Habachtal in Austria and with green beryls from the Ural Mts. Literature data for emeralds from Egypt andmodern-day Afghanistan area were used to interpret the results. Specifically, these sites were known for emeraldsbeing mined for jewellery in Roman times. It was assumed that emeralds from archaeological artefacts originatedfrom Habachtal in Austria, given that this site was the nearest to the place where found. But the emeralds fromthe necklace and earrings in fact came from Egyptian deposits. The origin of emeralds from the bracelet could nothave been determined absolutely reliably due to the lack of comparative materials; they may originate from a site inmodern-day Afghanistan or from Egypt, but certainly not from the same site as the previously mentioned emeraldsin the necklace and earrings.

Primary flow meter for calibrating a sniffer test leak artefact by a pressure rise method

Science.gov (United States)

Arai, Kenta; Yoshida, Hajime

2014-10-01

Sniffer tests are used to locate leaks in equipment during operation. The sensitivity of a sniffer leak detector must be calibrated against a known gas flow to atmospheric pressure generated by a sniffer test leak artefact. We have developed a primary flow meter for calibrating gas flows to atmospheric pressure through the leak artefact. The flow meter is based on a pressure rise method and two chambers are used to measure the pressure rise with small uncertainty even at atmospheric pressure. The calibration range of the flow rate is 5 × 10-7 Pa m3 s-1 to 7 × 10-4 Pa m3 s-1 to atmospheric pressure at 23.0 °C with a minimum uncertainty of 1.4% (k = 2), as well as 4 × 10-8 Pa m3 s-1 to 5 × 10-4 Pa m3 s-1 to a vacuum at 23.0 °C. The long term stability of the flow meter was determined as 0.41% by repeated measurements of the conductance of the leak artefact. In case of the flow rate into a vacuum, the flow meter was successfully linked to the international reference value of CCM.P-K12 by a lab-internal comparison.

Persuasiveness, Personalization & Productive Workplace Practices with IT-Knowledge Artefacts

DEFF Research Database (Denmark)

Fischer, Louise Harder; Pries-Heje, Lene

2016-01-01

work. We see a possible way forward for improving workplace practices with IT-knowledge artefact based applications, by combining new insight of how different personality traits prefer different knowledge sharing processes with new insight on personalizing persuasive technology. We explore new research......The workplace is getting increasingly globalized, virtualized and networked. At the same time, work itself has become discrete, autonomous and complex. In a fast changing world, the individual knowledge worker and his interactions becomes the new locus of value creation. Management promote...

A flint artefact (Accession No. DONMG 2016.7.1 from Lindholme, South Yorkshire

Directory of Open Access Journals (Sweden)

Alan Saville

2016-09-01

Full Text Available One of the last papers which Alan was working on when he died was a short note on a flint artefact from the surface of a gravel scrape at Lindholme in South Yorkshire. This was found during fieldwork by Robert Friend, a postgraduate student in Geography at the University of Edinburgh, working on the limits of the last glaciation in the Vale of York (Friend 2011. The results of this have been published elsewhere (Bateman et al. 2015; Friend et al. 2016, but the context of the artefact is ambivalent and Alan’s appendix on the flint was judged too archaeological and site specific for inclusion in either paper. It is a find, however, worth placing on record as one of a number of scattered surface finds of Upper Palaeolithic affinity from the region (compare with Garton et al. 2016; Grassam & Weston 2015; Harding et al. 2014.

The effect of magnetisation transfer contrast on cerebrospinal fluid on motion artefacts on fluid-attenuated inversion-recovery images

International Nuclear Information System (INIS)

Aprile, I.; Principi, M.; Ottaviano, P.; Scapeccia, M.

2003-01-01

We assessed possible advantages of the use of fluid-attenuated inversion-recovery (FLAIR) sequences with magnetisation-transfer contrast (MTC) over conventional FLAIR images. We carried out cranial MRI at 1 tesla on 50 patients with both sequences. In nine patients with multiple sclerosis (MS) we performed a quantitative comparison of the two sequences, looking at the contrast-to-noise ratio between lesions and normal white matter and counting the number of lesions shown using each method. A qualitative comparison on all patients consisted of the analysis of the appearance of the normal parenchyma, of any lesions, and of artefacts, with particular reference to cerebrospinal fluid (CSF) motion artefacts. The quantitative analysis showed no meaningful difference between the two sequences. The cerebral parenchyma and lesions appeared substantially the same with both techniques. With FLAIR MTC there was a clear, and consistent reduction in CSF motion artefacts. FLAIR MTC sequences can usefully be used in place of the conventional sequence at 1 tesla. (orig.)

Reducing beam hardening effects and metal artefacts using Medipix3RX: With applications from biomaterial science

CERN Document Server

Rajendran, K; de Ruiter, N J A; Chernoglazov, A I; Panta, R K; Butler, A P H; Butler, P H; Bell, S T; Anderson, N G; Woodfield, T B F; Tredinnick, S J; Healy, J L; Bateman, C J; Aamir, R; Doesburg, R M N; Renaud, P F; Gieseg, S P; Smithies, D J; Mohr, J L; Mandalika, V B H; Opie, A M T; Cook, N J; Ronaldson, J P; Nik, S J; Atharifard, A; Clyne, M; Bones, P J; Bartneck, C; Grasset, R; Schleich, N; Billinghurst, M

2014-01-01

This paper discusses methods for reducing beam hardening effects using spectral data for biomaterial applications. A small-animal spectral scanner operating in the diagnostic energy range was used. We investigate the use of photon-processing features of the Medipix3RX ASIC in reducing beam hardening and associated artefacts. A fully operational charge summing mode was used during the imaging routine. We present spectral data collected for metal alloy samples, its analysis using algebraic 3D reconstruction software and volume visualisation using a custom volume rendering software. Narrow high energy acquisition using the photon-processing detector revealed substantial reduction in beam hardening effects and metal artefacts.

Colloids or artefacts? A TVO/SKB cooperation project in Olkiluoto, Finland

International Nuclear Information System (INIS)

Laaksoharju, M.; Vuorinen, U.; Snellman, M.; Helenius, J.; Allard, B.; Pettersson, C.; Hinkkanen, H.

1993-12-01

TVO (Teollisuuden Voima Oy, Finland) initiated a co-operative task with SKB (Swedish Nuclear Fuel and Waste Management Co.) to critically evaluate colloid sampling methods at the test site in Olkiluoto, SW Finland. Three different colloid sampling methods were compared when sampling borehole OL-KR1 at 613-618 m depth. One possible way to make a conservative in-situ colloid estimation is to omit the contribution from calcite precipitation which is considered to be the main artefact. When this is made the inorganic colloid content (size 1-1000 nm) in Olkiluoto is 184 ±177 ppb consisting of clay minerals, silica, pyrite, goethite and magnesium oxide; the concentration of organic substances are around 100 ppb. The in-situ colloid concentration seems to be low which is in good agreement with experiences from years of sampling in similar environment and depths. The exercise shows the many difficulties encountered when sampling colloids. Small error in the planning, pump rate selection, a lack of precautionary measures, artefact sensitivity of the method etc have a tendency to affect significantly the results on the measured ppb colliod level

Multi-secular corrosion behaviour of low carbon steel in anoxic soils: Characterisation of corrosion system on archaeological artefacts

International Nuclear Information System (INIS)

Saheb, M.; Neff, D.; Dillmann, P.; Foy, E.; Saheb, M.; Dillmann, P.; Matthiesen, H.; Bellot-Gurlet, L.

2009-01-01

In the context of the prediction of materials behaviour used in the nuclear waste storage, the understanding of iron corrosion mechanisms in anoxic environment is of great importance. Information can be obtained using complementary analytical tools. Interactions between burial soil and archaeological artefacts are studied by performing on site soil measurements. Moreover, archaeological artefacts are studied on transverse sections using a combination of microbeam techniques. The specific interest of this project lies in the study of ferrous thick corrosion layers formed in anoxic environment. (authors)

Spatial analysis of "crazy quilts", a class of potentially random aesthetic artefacts.

Directory of Open Access Journals (Sweden)

Gesche Westphal-Fitch

Full Text Available Human artefacts in general are highly structured and often display ordering principles such as translational, reflectional or rotational symmetry. In contrast, human artefacts that are intended to appear random and non symmetrical are very rare. Furthermore, many studies show that humans find it extremely difficult to recognize or reproduce truly random patterns or sequences. Here, we attempt to model two-dimensional decorative spatial patterns produced by humans that show no obvious order. "Crazy quilts" represent a historically important style of quilt making that became popular in the 1870s, and lasted about 50 years. Crazy quilts are unusual because unlike most human artefacts, they are specifically intended to appear haphazard and unstructured. We evaluate the degree to which this intention was achieved by using statistical techniques of spatial point pattern analysis to compare crazy quilts with regular quilts from the same region and era and to evaluate the fit of various random distributions to these two quilt classes. We found that the two quilt categories exhibit fundamentally different spatial characteristics: The patch areas of crazy quilts derive from a continuous random distribution, while area distributions of regular quilts consist of Gaussian mixtures. These Gaussian mixtures derive from regular pattern motifs that are repeated and we suggest that such a mixture is a distinctive signature of human-made visual patterns. In contrast, the distribution found in crazy quilts is shared with many other naturally occurring spatial patterns. Centroids of patches in the two quilt classes are spaced differently and in general, crazy quilts but not regular quilts are well-fitted by a random Strauss process. These results indicate that, within the constraints of the quilt format, Victorian quilters indeed achieved their goal of generating random structures.

Spatial analysis of "crazy quilts", a class of potentially random aesthetic artefacts.

Science.gov (United States)

Westphal-Fitch, Gesche; Fitch, W Tecumseh

2013-01-01

Human artefacts in general are highly structured and often display ordering principles such as translational, reflectional or rotational symmetry. In contrast, human artefacts that are intended to appear random and non symmetrical are very rare. Furthermore, many studies show that humans find it extremely difficult to recognize or reproduce truly random patterns or sequences. Here, we attempt to model two-dimensional decorative spatial patterns produced by humans that show no obvious order. "Crazy quilts" represent a historically important style of quilt making that became popular in the 1870s, and lasted about 50 years. Crazy quilts are unusual because unlike most human artefacts, they are specifically intended to appear haphazard and unstructured. We evaluate the degree to which this intention was achieved by using statistical techniques of spatial point pattern analysis to compare crazy quilts with regular quilts from the same region and era and to evaluate the fit of various random distributions to these two quilt classes. We found that the two quilt categories exhibit fundamentally different spatial characteristics: The patch areas of crazy quilts derive from a continuous random distribution, while area distributions of regular quilts consist of Gaussian mixtures. These Gaussian mixtures derive from regular pattern motifs that are repeated and we suggest that such a mixture is a distinctive signature of human-made visual patterns. In contrast, the distribution found in crazy quilts is shared with many other naturally occurring spatial patterns. Centroids of patches in the two quilt classes are spaced differently and in general, crazy quilts but not regular quilts are well-fitted by a random Strauss process. These results indicate that, within the constraints of the quilt format, Victorian quilters indeed achieved their goal of generating random structures.

Algorithms that eliminate the effects of calibration artefact and trial-imposed offsets of Masimo oximeter in BOOST-NZ trial.

Science.gov (United States)

Zahari, Marina; Lee, Dominic Savio; Darlow, Brian Alexander

2016-10-01

The displayed readings of Masimo pulse oximeters used in the Benefits Of Oxygen Saturation Targeting (BOOST) II and related trials in very preterm babies were influenced by trial-imposed offsets and an artefact in the calibration software. A study was undertaken to implement new algorithms that eliminate the effects of offsets and artefact. In the BOOST-New Zealand trial, oxygen saturations were averaged and stored every 10 s up to 36 weeks' post-menstrual age. Two-hundred and fifty-seven of 340 babies enrolled in the trial had at least two weeks of stored data. Oxygen saturation distribution patterns corresponding with a +3 % or -3 % offset in the 85-95 % range were identified together with that due to the calibration artefact. Algorithms involving linear and quadratic interpolations were developed, implemented on each baby of the dataset and validated using the data of a UK preterm baby, as recorded from Masimo oximeters with the original software and a non-offset Siemens oximeter. Saturation distributions obtained were compared for both groups. There were a flat region at saturations 85-87 % and a peak at 96 % from the lower saturation target oximeters, and at 93-95 and 84 % respectively from the higher saturation target oximeters. The algorithms lowered the peaks and redistributed the accumulated frequencies to the flat regions and artefact at 87-90 %. The resulting distributions were very close to those obtained from the Siemens oximeter. The artefact and offsets of the Masimo oximeter's software had been addressed to determine the true saturation readings through the use of novel algorithms. The implementation would enable New Zealand data be included in the meta-analysis of BOOST II trials, and be used in neonatal oxygen studies.

Pixeanalysis of some artefacts from the first Bulgarian capital pliska in 9th-11th centuries

International Nuclear Information System (INIS)

Georgiev, Pavel; Ilieva, Galina; Penev, Ilia; Tzekova, Galina; Pantelica, Dan; Pantelica, Ana; Ionescu, Paul; Gugiu, Marius; Fluerasu, Daniela; Calinescu, Ionut C.; Costache, Cristian

2014-01-01

Proton Induced X-ray Emission (PIXE) technique has been applied to determine major, minor and trace elements in 20 metallic and glass artefacts discovered in 2012 from the archaeological site Pliska, the old capital of Bulgaria in 9th-11th centuries. PIXE analysis was performed using a 3 MeV proton beam in vacuum at the 9 MeV Van de Graaff Tandem accelerator of IFIN-HH in Bucharest-Magurele, Romania. The GUPIX (Guelph PIXE) programme was employed to determine the quantities of around 30 elements (Z ≥ 14) in the investigated samples. The obtained results were compared with literature data for the medieval epoch in Bulgaria. Key words: PIXE, elemental content, artefacts, metal, glass, Pliska, Bulgaria

Image quality and artefact generation post-cerebral aneurysm clipping using a 64-row multislice computer tomography angiography (MSCTA) technology: A retrospective study and review of the literature.

Science.gov (United States)

Zachenhofer, Iris; Cejna, Manfred; Schuster, Antonius; Donat, Markus; Roessler, Karl

2010-06-01

Computed tomography angiography (CTA) is a time and cost saving investigation for postoperative evaluation of clipped cerebral aneurysm patients. A retrospective study was conducted to analyse image quality and artefact generation due to implanted aneurysm clips using a new technology. MSCTA was performed pre- and postoperatively using a Philips Brilliance 64-detector-row CT scanner. Altogether, 32 clipping sites were analysed in 27 patients (11 female and 16 male, mean ages 52a, from 24 to 72 years). Clip number per aneurysm was 2.3 mean (from 1 to 4), 54 clips were made of titanium alloy and 5 of cobalt alloy. Altogether, image quality was rated 1.8 mean, using a scale from 1 (very good) to 5 (unserviceable) and clip artefacts were rated 2.4 mean, using a 5 point rating scale (1 no artefacts, 5 unserviceable due to artefacts). A significant loss of image quality and rise of artefacts was found when using cobalt alloy clips (1.4 versus 4.2 and 2.1 versus 4.0). In 72% of all investigations, an excellent image quality was found. Excluding the cobalt clip group, 85% of scans showed excellent image quality. Artefacts were absent or minimal (grade 1 or 2) in 69% of all investigations and in 81% in the pure titanium clip group. In 64-row MSCTA of good image quality with low artefacts, it was possible to detect small aneurysm remnants of 2mm size in individual patients. By using titanium alloy clips, in our study up to 85% of postoperative CTA images were of excellent quality with absent or minimal artefacts in 81% and seem adequate to detect small aneurysm remnants. Copyright 2010 Elsevier B.V. All rights reserved.

Lesion concordance, image quality and artefacts in PET/CT. Results of a multicenter study

International Nuclear Information System (INIS)

Stergar, H.; Bockisch, A.; Krause, B.J.; Eschmann, S.M.; Juergens, K.U.; Kuehl, H.; Pfannenberg, A.C.; Stollfuss, J.; Weckesser, M.

2010-01-01

This study had three major objectives: (1.) to record the number of concordant (both in PET and CT) pathological lesions in different body regions/organs, (2.) to evaluate the image quality and (3.) to determine both, the quantity and the quality of artefacts in whole body FDG PET/CT scans. Routine whole body scans of 353 patients referred to FDG-PET/CT exams at 4 university hospitals were employed. All potentially malignant lesions in 13 different body regions/organs were classified as either concordant or suspicious in FDG-PET or CT only. In the latter case the diagnostic relevance of this disparity was judged. The image quality in PET and CT was rated as a whole and separately in 5 different body regions. Furthermore we investigated the frequency and site of artefacts caused by metal implants and oral or intravenous contrast media as well as the subjective co-registration quality (in 4 body regions) and the diagnostic impact of such artefacts or misalignment. In addition, the readers rated the diagnostic gain of adding the information from the other tomographic method. In total 1941 lesions (5.5 per patient) were identified, 1094 (56%) out of which were concordant. 602 (71%) out of the 847 remaining lesions were detected only with CT, 245 (29%) were only PET-positive. As expected, CT particularly depicted the majority of lesions in the lungs and abdominal organs. However, the diagnostic relevance was greater with PET-only positive lesions. Most of the PET/CT scans were performed with full diagnostic CT including administration of oral and intravenous contast media (> 80%). The image quality in PET and CT was rated excellent. Artefacts occurred in more than 60% of the scans and were mainly due to (dental) metal implants and contrast agent. Nevertheless there was almost no impact on diagnostic confidence if reading of the non attenuation corrected PET was included. The co-registration quality in general was also rated as excellent. Misalignment mostly occurred due

Heat conduction

International Nuclear Information System (INIS)

Grigull, U.; Sandner, H.

1984-01-01

Included are discussions of rates of heat transfer by conduction, the effects of varying and changing properties, thermal explosions, distributed heat sources, moving heat sources, and non-steady three-dimensional conduction processes. Throughout, the importance of thinking both numerically and symbolically is stressed, as this is essential to the development of the intuitive understanding of numerical values needed for successful designing. Extensive tables of thermophysical properties, including thermal conductivity and diffusivity, are presented. Also included are exact and approximate solutions to many of the problems that arise in practical situations

The development of equipment for the technical assessment of respiratory motion induced artefacts in MRI

International Nuclear Information System (INIS)

Jackson, P.C.; Davies, S.C.; Zananiri, F.V.; Follett, D.H.; Halliwell, M.; Wells, P.N.T.; Bean, J.P.

1993-01-01

A device and technique to study the effects of respiratory motion on the quality of magnetic resonance images is proposed. The construction of the device enables a variety of test objects to be mounted and used in the evaluation of imaging parameters that may be affected by motion. The equipment is constructed of cast acrylic and the movement is actuated and controlled pneumatically thus ensuring that there are no interactions with the magnetic field and radiofrequency detection system to cause further image artefacts. Separate studies have been performed, using ultrasound, to assess the degree and rate of movement of organs owing to respiration in order to derive the motion parameters for the apparatus. Preliminary results indicate that the technique produces motion induced artefacts simulating those which are the result of the effects of respiration. (author)

Metal artefact suppression at 3 T MRI: comparison of MAVRIC-SL with conventional fast spin echo sequences in patients with Hip joint arthroplasty

International Nuclear Information System (INIS)

Kretzschmar, Martin; Nardo, Lorenzo; Han, Misung M.; Heilmeier, Ursula; Sam, Craig; Joseph, Gabby B.; Krug, Roland; Link, Thomas M.; Koch, Kevin M.

2015-01-01

The aim of our study was to evaluate the clinical feasibility and diagnostic value of a new MRI metal artefact reduction pulse sequence called MAVRIC-SL in a 3 T MRI environment. Two MAVRIC-SL sequences obtained in 61 patients with symptomatic total hip replacement were compared with standard FSE-STIR sequences optimized for imaging around metal. Artefact size was measured on the slice of greatest extent. Image quality, fat saturation, image distortion, visibility of anatomical structures, and detectability of joint abnormalities were visually assessed and graded on qualitative scales. Differences between MAVRIC-SL and FSE sequences were tested with the Wilcoxon signed-rank test. MAVRIC-SL sequences at 3 T showed significantly smaller metal artefacts compared to FSE-STIR sequences (p < 0.0001). The general image quality of MAVRIC-SL sequences was reduced with regard to spatial resolution, noise and contrast (p = 0.001), and fat saturation (p < 0.0001). The reduction of artefact size and image distortion significantly improved visualization of joint anatomy (p < 0.0001) and diagnostic confidence regarding implant-associated abnormalities (p = 0.0075 to <0.0001). Although the image quality of MAVRIC-SL sequences is limited at 3 T, its clinical application is feasible and provides important additional diagnostic information for the workup of patients with symptomatic hip replacement through substantially reduced metal artefacts. (orig.)

Metal artefact suppression at 3 T MRI: comparison of MAVRIC-SL with conventional fast spin echo sequences in patients with Hip joint arthroplasty

Energy Technology Data Exchange (ETDEWEB)

Kretzschmar, Martin; Nardo, Lorenzo; Han, Misung M.; Heilmeier, Ursula; Sam, Craig; Joseph, Gabby B.; Krug, Roland; Link, Thomas M. [University of California San Francisco, Musculoskeletal Quantitative Imaging Research Group, Department of Radiology and Biomedical Imaging, San Francisco, CA (United States); Koch, Kevin M. [Medical Collage of Wisconsin, Departments of Biophysics and Radiology, Milwaukee, WI (United States)

2015-08-15

The aim of our study was to evaluate the clinical feasibility and diagnostic value of a new MRI metal artefact reduction pulse sequence called MAVRIC-SL in a 3 T MRI environment. Two MAVRIC-SL sequences obtained in 61 patients with symptomatic total hip replacement were compared with standard FSE-STIR sequences optimized for imaging around metal. Artefact size was measured on the slice of greatest extent. Image quality, fat saturation, image distortion, visibility of anatomical structures, and detectability of joint abnormalities were visually assessed and graded on qualitative scales. Differences between MAVRIC-SL and FSE sequences were tested with the Wilcoxon signed-rank test. MAVRIC-SL sequences at 3 T showed significantly smaller metal artefacts compared to FSE-STIR sequences (p < 0.0001). The general image quality of MAVRIC-SL sequences was reduced with regard to spatial resolution, noise and contrast (p = 0.001), and fat saturation (p < 0.0001). The reduction of artefact size and image distortion significantly improved visualization of joint anatomy (p < 0.0001) and diagnostic confidence regarding implant-associated abnormalities (p = 0.0075 to <0.0001). Although the image quality of MAVRIC-SL sequences is limited at 3 T, its clinical application is feasible and provides important additional diagnostic information for the workup of patients with symptomatic hip replacement through substantially reduced metal artefacts. (orig.)

The characterisation of Melanesian obsidian sources and artefacts using the proton induced gamma-ray emission (PIGME) technique

International Nuclear Information System (INIS)

Bird, J.R.; Ambrose, W.R.; Russell, L.H.; Scott, M.D.

1981-09-01

Proton induced gamma-ray emission (PIGME) has been used to determine F, Na and Al concentrations in obsidian from known locations in Melanesia and to relate artefacts from this region to such sources. The PIGME technique is a fast, non-destructive, and accurate method for determining these three elements with essentially no special sample preparation. The measuring technique is described and results are listed for sources, chiefly in the Papua New Guinea region. Their classification is discussed in terms of groups which are distinguishable by the PIGME method. Over 700 artefact results are listed; these show the occurrence of an additional group that is not geographically identified

Sci—Fri PM: Dosimetry—01: Radiation-induced refraction artefacts in the optical CT readout of polymer gel dosimeters

International Nuclear Information System (INIS)

Campbell, Warren G; Jirasek, Andrew; Wells, Derek M

2014-01-01

Polymer gel dosimeters (PGDs) are a desirable tool for the verification of advanced radiotherapy treatments. Fully 3D, deformable, and tissue-equivalent, the PGD polymerizes wherever it absorbs dose. To measure the dose absorbed by a PGD, optical computed tomography (CT) can be used to evaluate, in full 3D, the opacity distribution that coincides with polymerization. In addition to an increase in opacity with dose, an increase in refractive index (RI) is also known to occur in irradiated polymer gels. The increase in RI is slight and was previously assumed insignificant. This work reveals the effects that radiation-induced RI changes can have on the optical CT readout of PGDs. A fan-beam optical CT scanner was used to image a cylindrical PGD irradiated by a pair of 3×3 cm 2 , 6 MV photon beams in an orthogonal arrangement. Investigative scans were performed to evaluate refraction errors occurring: i) within the plane, and ii) out of the plane of the fan-beam. In-plane refraction was shown to cause distinct streaking artefacts along dose gradients (i.e. RI gradients) due to higher intensity rays being refracted into more opaque regions. Out-of-plane refraction was shown to produce severe, widespread artefacts due to rays missing the detector array. An iterative Savitzky-Golay filtering technique was developed to reduce both types of artefacts by specifically targeting structured errors in sinogram space. Results introduce a new category of imaging artefacts to be aware of when using optical CT for PGD readout

Introduction. Leave no stone unturned: Perspectives on ground stone artefact research

OpenAIRE

Danny Rosenberg; Yorke Rowan; Tatjana Gluhak

2016-01-01

Ground stone tools served in many physical and social contexts through millennia, reflecting a wide variety of functions. Although ground stone tool studies were neglected for much of early archaeology, the last few decades witnessed a notable international uptick in the way archaeologists confront this multifaceted topic. Today, with the advance of archaeology as a discipline, research into ground stone artefacts is moving into a new phase that integrates high resolution documentation with n...

Spatial Analysis of “Crazy Quilts”, a Class of Potentially Random Aesthetic Artefacts

Science.gov (United States)

Westphal-Fitch, Gesche; Fitch, W. Tecumseh

2013-01-01

Human artefacts in general are highly structured and often display ordering principles such as translational, reflectional or rotational symmetry. In contrast, human artefacts that are intended to appear random and non symmetrical are very rare. Furthermore, many studies show that humans find it extremely difficult to recognize or reproduce truly random patterns or sequences. Here, we attempt to model two-dimensional decorative spatial patterns produced by humans that show no obvious order. “Crazy quilts” represent a historically important style of quilt making that became popular in the 1870s, and lasted about 50 years. Crazy quilts are unusual because unlike most human artefacts, they are specifically intended to appear haphazard and unstructured. We evaluate the degree to which this intention was achieved by using statistical techniques of spatial point pattern analysis to compare crazy quilts with regular quilts from the same region and era and to evaluate the fit of various random distributions to these two quilt classes. We found that the two quilt categories exhibit fundamentally different spatial characteristics: The patch areas of crazy quilts derive from a continuous random distribution, while area distributions of regular quilts consist of Gaussian mixtures. These Gaussian mixtures derive from regular pattern motifs that are repeated and we suggest that such a mixture is a distinctive signature of human-made visual patterns. In contrast, the distribution found in crazy quilts is shared with many other naturally occurring spatial patterns. Centroids of patches in the two quilt classes are spaced differently and in general, crazy quilts but not regular quilts are well-fitted by a random Strauss process. These results indicate that, within the constraints of the quilt format, Victorian quilters indeed achieved their goal of generating random structures. PMID:24066095

The fourth dimension of tool use: temporally enduring artefacts aid primates learning to use tools.

Science.gov (United States)

Fragaszy, D M; Biro, D; Eshchar, Y; Humle, T; Izar, P; Resende, B; Visalberghi, E

2013-11-19

All investigated cases of habitual tool use in wild chimpanzees and capuchin monkeys include youngsters encountering durable artefacts, most often in a supportive social context. We propose that enduring artefacts associated with tool use, such as previously used tools, partly processed food items and residual material from previous activity, aid non-human primates to learn to use tools, and to develop expertise in their use, thus contributing to traditional technologies in non-humans. Therefore, social contributions to tool use can be considered as situated in the three dimensions of Euclidean space, and in the fourth dimension of time. This notion expands the contribution of social context to learning a skill beyond the immediate presence of a model nearby. We provide examples supporting this hypothesis from wild bearded capuchin monkeys and chimpanzees, and suggest avenues for future research.

DOUBLE TRIALS METHOD FOR NONLINEAR PROBLEMS ARISING IN HEAT TRANSFER

Directory of Open Access Journals (Sweden)

Chun-Hui He

2011-01-01

Full Text Available According to an ancient Chinese algorithm, the Ying Buzu Shu, in about second century BC, known as the rule of double false position in West after 1202 AD, two trial roots are assumed to solve algebraic equations. The solution procedure can be extended to solve nonlinear differential equations by constructing an approximate solution with an unknown parameter, and the unknown parameter can be easily determined using the Ying Buzu Shu. An example in heat transfer is given to elucidate the solution procedure.

From Governing through Data to Governmentality through Data: Artefacts, Strategies and the Digital Turn

Science.gov (United States)

Souto-Otero, Manuel; Beneito-Montagut, Roser

2016-01-01

The article argues that current discussions about governance through data in education can be fruitfully extended through: (1) the establishment of connections with wider debates about the role of commensuration processes and governmentality in the recreation of education systems; (2) greater emphasis on the "artefacts" through which…

Is it so bad? Energy consumption and changes in stocks of energy-converting artefacts

Energy Technology Data Exchange (ETDEWEB)

Bladh, Mats (Department of Thematic Studies, Technology and Social Change, Linkoeping University (Sweden))

2011-07-01

The development of total energy consumption is important in a world with limited resources. It is the result of two basic tendencies working in opposite directions: growth in use (such as more cars) and improvements in energy efficiency (such as more fuel-efficient engines). Since the 1970s energy consumption has stagnated in Sweden. This means that increasing supply has been counteracted by measures improving overall energy efficiency to a larger degree than before. How can longterm development in energy consumption be analysed? This paper proposes a change-of-stock model as a tool for such analyses. In order to show the fruitfulness of this approach, historical data on cars, dwellings and lamps in Sweden are used. The basic idea is that changes in composition, size and use of stocks of these energy converters explain energy consumption. Gains in efficiency can be reached in two ways, either through changing technological path (such as electric cars instead of petrol-driven cars) or improvements within the path taken (such as fuel-efficient combustion engines). As the existence of path dependence is assumed here, it is expected that the latter will dominate. But does that mean small gains in energy saved? Results from the cases in this paper show considerable gains of efficiency in fuel consumption in private cars, and heating efficiency in multi-dwelling houses. Thus, incremental changes are important, but are partially offset by changes in characteristics of the artefacts. Radical changes, such as the factual change from air to rail transportation, and a counterfactual double switch from gasoline to electric cars and from electric heating to district heating, as well as probable gains from the phase-out of incandescent lamps, show even bigger gains. Both incremental and radical changes are the subject of counteracting tendencies, of a broader nature than that associated with rebound effects, such as more cars per inhabitant and fewer people in each dwelling. The

Magnetic resonance imaging acquisition techniques intended to decrease movement artefact in paediatric brain imaging: a systematic review

International Nuclear Information System (INIS)

Woodfield, Julie; Kealey, Susan

2015-01-01

Attaining paediatric brain images of diagnostic quality can be difficult because of young age or neurological impairment. The use of anaesthesia to reduce movement in MRI increases clinical risk and cost, while CT, though faster, exposes children to potentially harmful ionising radiation. MRI acquisition techniques that aim to decrease movement artefact may allow diagnostic paediatric brain imaging without sedation or anaesthesia. We conducted a systematic review to establish the evidence base for ultra-fast sequences and sequences using oversampling of k-space in paediatric brain MR imaging. Techniques were assessed for imaging time, occurrence of movement artefact, the need for sedation, and either image quality or diagnostic accuracy. We identified 24 relevant studies. We found that ultra-fast techniques had shorter imaging acquisition times compared to standard MRI. Techniques using oversampling of k-space required equal or longer imaging times than standard MRI. Both ultra-fast sequences and those using oversampling of k-space reduced movement artefact compared with standard MRI in unsedated children. Assessment of overall diagnostic accuracy was difficult because of the heterogeneous patient populations, imaging indications, and reporting methods of the studies. In children with shunt-treated hydrocephalus there is evidence that ultra-fast MRI is sufficient for the assessment of ventricular size. (orig.)

Magnetic resonance imaging acquisition techniques intended to decrease movement artefact in paediatric brain imaging: a systematic review

Energy Technology Data Exchange (ETDEWEB)

Woodfield, Julie [University of Edinburgh, Child Life and Health, Edinburgh (United Kingdom); Kealey, Susan [Western General Hospital, Department of Neuroradiology, Edinburgh (United Kingdom)

2015-08-15

Attaining paediatric brain images of diagnostic quality can be difficult because of young age or neurological impairment. The use of anaesthesia to reduce movement in MRI increases clinical risk and cost, while CT, though faster, exposes children to potentially harmful ionising radiation. MRI acquisition techniques that aim to decrease movement artefact may allow diagnostic paediatric brain imaging without sedation or anaesthesia. We conducted a systematic review to establish the evidence base for ultra-fast sequences and sequences using oversampling of k-space in paediatric brain MR imaging. Techniques were assessed for imaging time, occurrence of movement artefact, the need for sedation, and either image quality or diagnostic accuracy. We identified 24 relevant studies. We found that ultra-fast techniques had shorter imaging acquisition times compared to standard MRI. Techniques using oversampling of k-space required equal or longer imaging times than standard MRI. Both ultra-fast sequences and those using oversampling of k-space reduced movement artefact compared with standard MRI in unsedated children. Assessment of overall diagnostic accuracy was difficult because of the heterogeneous patient populations, imaging indications, and reporting methods of the studies. In children with shunt-treated hydrocephalus there is evidence that ultra-fast MRI is sufficient for the assessment of ventricular size. (orig.)

Persistent Artefacts in an Online Classroom: The Value of a Dynamic Learning Archive

Science.gov (United States)

Berry, Stuart C.

2016-01-01

This paper summarizes a multi-year research project that examines the use and value of visible and persistent artefacts within an online learning environment. This study is framed within elements of a business management theory. Changes to an online learning environment are documented as well as an examination of the impact of these changes on the…

The Mediation of Teaching and Learning Processes through "Identity Artefacts." A Vygotskian Perspective

Science.gov (United States)

Subero, David; Llopart, Mariona; Siqués, Carina; Esteban-Guitart, Moises

2018-01-01

The aim of this paper is to address the teaching and learning processes in schools from a Vygotskian perspective based on the notion of "identity artefacts" (IAs) which, for our purposes, consist of documents created by the learners about themselves, in which they try to capture all the things that make sense and are meaningful to them…

SU-E-J-158: Audiovisual Biofeedback Reduces Image Artefacts in 4DCT: A Digital Phantom Study

Energy Technology Data Exchange (ETDEWEB)

Pollock, S; Kipritidis, J; Lee, D; Keall, P [University of Sydney, Sydney (Australia); Bernatowicz, K [Paul Scherrer Institute, Psi, Aargau (Switzerland)

2015-06-15

Purpose: Irregular breathing motion has a deleterious impact on 4DCT image quality. The breathing guidance system: audiovisual biofeedback (AVB) is designed to improve breathing regularity, however, its impact on 4DCT image quality has yet to be quantified. The purpose of this study was to quantify the impact of AVB on thoracic 4DCT image quality by utilizing the digital eXtended Cardiac Torso (XCAT) phantom driven by lung tumor motion patterns. Methods: 2D tumor motion obtained from 4 lung cancer patients under two breathing conditions (i) without breathing guidance (free breathing), and (ii) with guidance (AVB). There were two breathing sessions, yielding 8 tumor motion traces. This tumor motion was synchronized with the XCAT phantom to simulate 4DCT acquisitions under two acquisition modes: (1) cine mode, and (2) prospective respiratory-gated mode. Motion regularity was quantified by the root mean square error (RMSE) of displacement. The number of artefacts was visually assessed for each 4DCT and summed up for each breathing condition. Inter-session anatomic reproducibility was quantified by the mean absolute difference (MAD) between the Session 1 4DCT and Session 2 4DCT. Results: AVB improved tumor motion regularity by 30%. In cine mode, the number of artefacts was reduced from 61 in free breathing to 40 with AVB, in addition to AVB reducing the MAD by 34%. In gated mode, the number of artefacts was reduced from 63 in free breathing to 51 with AVB, in addition to AVB reducing the MAD by 23%. Conclusion: This was the first study to compare the impact of breathing guidance on 4DCT image quality compared to free breathing, with AVB reducing the amount of artefacts present in 4DCT images in addition to improving inter-session anatomic reproducibility. Results thus far suggest that breathing guidance interventions could have implications for improving radiotherapy treatment planning and interfraction reproducibility.

SU-E-J-158: Audiovisual Biofeedback Reduces Image Artefacts in 4DCT: A Digital Phantom Study

International Nuclear Information System (INIS)

Pollock, S; Kipritidis, J; Lee, D; Keall, P; Bernatowicz, K

2015-01-01

Purpose: Irregular breathing motion has a deleterious impact on 4DCT image quality. The breathing guidance system: audiovisual biofeedback (AVB) is designed to improve breathing regularity, however, its impact on 4DCT image quality has yet to be quantified. The purpose of this study was to quantify the impact of AVB on thoracic 4DCT image quality by utilizing the digital eXtended Cardiac Torso (XCAT) phantom driven by lung tumor motion patterns. Methods: 2D tumor motion obtained from 4 lung cancer patients under two breathing conditions (i) without breathing guidance (free breathing), and (ii) with guidance (AVB). There were two breathing sessions, yielding 8 tumor motion traces. This tumor motion was synchronized with the XCAT phantom to simulate 4DCT acquisitions under two acquisition modes: (1) cine mode, and (2) prospective respiratory-gated mode. Motion regularity was quantified by the root mean square error (RMSE) of displacement. The number of artefacts was visually assessed for each 4DCT and summed up for each breathing condition. Inter-session anatomic reproducibility was quantified by the mean absolute difference (MAD) between the Session 1 4DCT and Session 2 4DCT. Results: AVB improved tumor motion regularity by 30%. In cine mode, the number of artefacts was reduced from 61 in free breathing to 40 with AVB, in addition to AVB reducing the MAD by 34%. In gated mode, the number of artefacts was reduced from 63 in free breathing to 51 with AVB, in addition to AVB reducing the MAD by 23%. Conclusion: This was the first study to compare the impact of breathing guidance on 4DCT image quality compared to free breathing, with AVB reducing the amount of artefacts present in 4DCT images in addition to improving inter-session anatomic reproducibility. Results thus far suggest that breathing guidance interventions could have implications for improving radiotherapy treatment planning and interfraction reproducibility

Modification of heating system on HeaTiNG-02 test section of beta test loop

International Nuclear Information System (INIS)

Sagino; Dedy Haryanto; Riswan Djambiar; Edy Sumarno

2013-01-01

Modifications have been carried out on the heating test section heating-02 on the integration strand Beta Test (UUB). The activities carried out to overcome the obstacles that arise in the test section when used. Constraint that often arises is the fall of the heating source super chantal when it reaches a certain temperature. To mitigate the super chantal is initially converted into a horizontal vertical position. Change from vertical to horizontal position on super chantal aims to stabilize the position of super chantal, so it needs to be modified in the heating system. Modification activities include manufacturing, installation and testing of super chantal and refractory stone as super chantal support. Manufacturing refractory stone formation and assembly into the heater in accordance with design modifications that have been done in electromechanical workshop obtained using some machine tools. Testing results of fabrication has been done by providing voltage 110 volts until it reaches operating temperature 400°C. Test results obtained super chantal stable position when it reaches operating temperature, and heater of heating-02 test section feasible to be used for experiments. (author)

Reduction of artefacts caused by hip implants in CT-based attenuation-corrected PET images using 2-D interpolation of a virtual sinogram on an irregular grid

NARCIS (Netherlands)

Abdoli, Mehrsima; de Jong, Johan R.; Pruim, Jan; Dierckx, Rudi A. J. O.; Zaidi, Habib

2011-01-01

Purpose Metallic prosthetic replacements, such as hip or knee implants, are known to cause strong streaking artefacts in CT images. These artefacts likely induce over-or underestimation of the activity concentration near the metallic implants when applying CT-based attenuation correction of positron

Plasma cleaning and analysis of archeological artefacts from Sipan

Energy Technology Data Exchange (ETDEWEB)

Saettone, E A O [Instituto de Fisica, Universidade de Sao Paulo, Sao Paulo, CEP 05508-900 (Brazil); Matta, J A S da [Instituto de Fisica, Universidade de Sao Paulo, Sao Paulo, CEP 05508-900 (Brazil); Alva, W [Instituto de Fisica, Universidade de Sao Paulo, Sao Paulo, CEP 05508-900 (Brazil); Chubaci, J F O [Instituto de Fisica, Universidade de Sao Paulo, Sao Paulo, CEP 05508-900 (Brazil); Fantini, M C A [Instituto de Fisica, Universidade de Sao Paulo, Sao Paulo, CEP 05508-900 (Brazil); Galvao, R M O [Instituto de Fisica, Universidade de Sao Paulo, Sao Paulo, CEP 05508-900 (Brazil); Kiyohara, P [Instituto de Fisica, Universidade de Sao Paulo, Sao Paulo, CEP 05508-900 (Brazil); Tabacniks, M H [Instituto de Fisica, Universidade de Sao Paulo, Sao Paulo, CEP 05508-900 (Brazil)

2003-04-07

A novel procedure using plasma sputtering in an electron-cyclotron-resonance device has been applied to clean archeological MOCHE artefacts, unearthed at the Royal Tombs of Sipan. After successful cleaning, the pieces were analysed by a variety of complementary techniques, namely proton-induced x-ray emission, Rutherford backscattering spectroscopy, x-ray diffraction, electron microscopy, and inductively coupled plasma mass spectroscopy. With these techniques, it has been possible to not only determine the profiles of the gold and silver surface layers, but also to detect elements that may be relevant to explain the gilding techniques skillfully developed by the metal smiths of the MOCHE culture.

High intensity heat pulse problem

International Nuclear Information System (INIS)

Yalamanchili, R.

1977-01-01

The use of finite-difference methods for the solution of partial differential equations is common in both design and research and development because of the advance of computers. The numerical methods for the unsteady heat diffusion equation received most attention not only because of heat transfer problems but also happened to be the basis for any study of parabolic partial differential equations. It is common to test the heat equation first even the methods developed for complex nonlinear parabolic partial differential equations arising in fluid mechanics or convective heat transfer. It is concluded that the finite-element method is conservative in both stability and monoscillation characteristics than the finite-difference method but not as conservative as the method of weighted-residuals. Since the finite-element is unique because of Gurtin's variational principle and numerous finite-differences can be constructed, it is found that some finite-difference schemes are better than the finite-element scheme in accuracy also. Therefore, further attention is focused here on finite-difference schemes only. Various physical problems are considered in the field of heat transfer. These include: numerous problems in steady and unsteady heat conduction; heat pulse problems, such as, plasma torch; problems arising from machining operations, such as, abrasive cut-off and surface grinding. (Auth.)

Corrosion of archaeological iron artefacts compared to modern iron at the waterlogged site Nydam, Denmark

DEFF Research Database (Denmark)

Matthiesen, Henning; Hilbert, Lisbeth Rischel; Gregory, David

2004-01-01

focuses solely on the iron objects. A three-pronged approach has been used in the studies in Nydam: Studies of the excavated artefacts, including the compositon of corrosion products and a mapping of their exact state of preservation. 2) Use of modern iron samples placed in the soil for studies of weight......Since 1859 several archaeological excavations have been carried out in Nydam, Denmark revealing a wealth of military equipment sacrificed in the period 200 - 500 AD. During the 1990's more than 16000 artefacts of mainly wood and iron were excavated within an area of only 600 m2. Due to the volume...... loss, corrosion potential, electrochemical impedance spectroscopy and electrical resistivity. 3) Measurements of environmental parameter such as water level, redox potential, oxygen concentration, soil pH, and the concentration of a range of dissolved species in the pore water. This presentation shows...

Electrocardiographic artefacts mimicking atrial tachycardia resulted in unnecessary diagnostic and therapeutic measures

OpenAIRE

Y-Hassan, Shams; Sylv?n, Christer

2013-01-01

Electrocardiographic (ECG) artefacts may closely simulate both supraventricular and ventricular tachycardias. We describe a case initially diagnosed as rapid atrial fibrillation, based on 12-lead surface ECG (especially the limb leads) and monitor tracing. The arrhythmia was resistant to beta blockers. Because of the at times apparently regular rhythm, an esophageal ECG recording was performed, and adenosine was administered. When the presumed atrial fibrillation terminated after sodium pento...

Reduction in respiratory motion artefacts on gadoxetate-enhanced MRI after training technicians to apply a simple and more patient-adapted breathing command

International Nuclear Information System (INIS)

Gutzeit, Andreas; Matoori, Simon; Weymarn, Constantin von; Reischauer, Carolin; Goyen, Matthias; Hergan, Klaus; Meissnitzer, Matthias; Forstner, Rosemarie; Froehlich, Johannes M.; Kolokythas, Orpheus; Soyka, Jan D.; Doert, Aleksis; Koh, Dow-Mu

2016-01-01

To investigate whether a trained group of technicians using a modified breathing command during gadoxetate-enhanced liver MRI reduces respiratory motion artefacts compared to non-trained technicians using a traditional breathing command. The gadoxetate-enhanced liver MR images of 30 patients acquired using the traditional breathing command and the subsequent 30 patients after training the technicians to use a modified breathing command were analyzed. A subgroup of patients (n = 8) underwent scans both by trained and untrained technicians. Images obtained using the traditional and modified breathing command were compared for the presence of breathing artefacts [respiratory artefact-based image quality scores from 1 (best) to 5 (non-diagnostic)]. There was a highly significant improvement in the arterial phase image quality scores in patients using the modified breathing command compared to the traditional one (P < 0.001). The percentage of patients with severe and extensive breathing artefacts in the arterial phase decreased from 33.3 % to 6.7 % after introducing the modified breathing command (P = 0.021). In the subgroup that underwent MRI using both breathing commands, arterial phase image quality improved significantly (P = 0.008) using the modified breathing command. Training technicians to use a modified breathing command significantly improved arterial phase image quality of gadoxetate-enhanced liver MRI. (orig.)

New Integrals Arising in the Samara-Valencia Heat Transfer Model in Grinding

Directory of Open Access Journals (Sweden)

J. L. González-Santander

2017-01-01

Full Text Available The Samara-Valencia model for heat transfer in grinding has been recently used for calculating nontabulated integrals. Based on these results, new infinite integrals can be calculated, involving the Macdonald function and the modified Struve function.

X-ray fluorescence microscopy artefacts in elemental maps of topologically complex samples: Analytical observations, simulation and a map correction method

Science.gov (United States)

Billè, Fulvio; Kourousias, George; Luchinat, Enrico; Kiskinova, Maya; Gianoncelli, Alessandra

2016-08-01

XRF spectroscopy is among the most widely used non-destructive techniques for elemental analysis. Despite the known angular dependence of X-ray fluorescence (XRF), topological artefacts remain an unresolved issue when using X-ray micro- or nano-probes. In this work we investigate the origin of the artefacts in XRF imaging of topologically complex samples, which are unresolved problems in studies of organic matter due to the limited travel distances of low energy XRF emission from the light elements. In particular we mapped Human Embryonic Kidney (HEK293T) cells. The exemplary results with biological samples, obtained with a soft X-ray scanning microscope installed at a synchrotron facility were used for testing a mathematical model based on detector response simulations, and for proposing an artefact correction method based on directional derivatives. Despite the peculiar and specific application, the methodology can be easily extended to hard X-rays and to set-ups with multi-array detector systems when the dimensions of surface reliefs are in the order of the probing beam size.

Calibration artefacts in radio interferometry - III. Phase-only calibration and primary beam correction

Science.gov (United States)

Grobler, T. L.; Stewart, A. J.; Wijnholds, S. J.; Kenyon, J. S.; Smirnov, O. M.

2016-09-01

This is the third installment in a series of papers in which we investigate calibration artefacts. Calibration artefacts (also known as ghosts or spurious sources) are created when we calibrate with an incomplete model. In the first two papers of this series, we developed a mathematical framework which enabled us to study the ghosting mechanism itself. An interesting concomitant of the second paper was that ghosts appear in symmetrical pairs. This could possibly account for spurious symmetrization. Spurious symmetrization refers to the appearance of a spurious source (the antighost) symmetrically opposite an unmodelled source around a modelled source. The analysis in the first two papers indicates that the antighost is usually very faint, in particular, when a large number of antennas are used. This suggests that spurious symmetrization will mainly occur at an almost undetectable flux level. In this paper, we show that phase-only calibration produces an antighost that is N-times (where N denotes the number of antennas in the array) as bright as the one produced by phase and amplitude calibration and that this already bright ghost can be further amplified by the primary beam correction.

Computed tomography by reconstruction. Brain CT scanning. I. Basic physics, equipment, normal aspects, artefacts

International Nuclear Information System (INIS)

Chiras, J.; Palmieri, P.; Saudinos, J.; Salamon, G.

1980-01-01

The authors describe the physical basis, apparatus, normal images, and artefacts of computed tomography by reconstruction. Radio-anatomical sections enable clear comprehension of the computed tomography images. Other methods using computer reconstruction are outlined: tomography by Compton effect, tomography by positrons, tomography by gamma emission, tomography by protons, tomography by nuclear magnetic resonance [fr

Value of monoenergetic dual-energy CT (DECT) for artefact reduction from metallic orthopedic implants in post-mortem studies.

Science.gov (United States)

Filograna, Laura; Magarelli, Nicola; Leone, Antonio; Guggenberger, Roman; Winklhofer, Sebastian; Thali, Michael John; Bonomo, Lorenzo

2015-09-01

The aim of this ex vivo study was to assess the performance of monoenergetic dual-energy CT (DECT) reconstructions to reduce metal artefacts in bodies with orthopedic devices in comparison with standard single-energy CT (SECT) examinations in forensic imaging. Forensic and clinical impacts of this study are also discussed. Thirty metallic implants in 20 consecutive cadavers with metallic implants underwent both SECT and DECT with a clinically suitable scanning protocol. Extrapolated monoenergetic DECT images at 64, 69, 88, 105, 120, and 130 keV and individually adjusted monoenergy for optimized image quality (OPTkeV) were generated. Image quality of the seven monoenergetic images and of the corresponding SECT image was assessed qualitatively and quantitatively by visual rating and measurements of attenuation changes induced by streak artefact. Qualitative and quantitative analyses showed statistically significant differences between monoenergetic DECT extrapolated images and SECT, with improvements in diagnostic assessment in monoenergetic DECT at higher monoenergies. The mean value of OPTkeV was 137.6 ± 4.9 with a range of 130 to 148 keV. This study demonstrates that monoenergetic DECT images extrapolated at high energy levels significantly reduce metallic artefacts from orthopedic implants and improve image quality compared to SECT examination in forensic imaging.

Value of monoenergetic dual-energy CT (DECT) for artefact reduction from metallic orthopedic implants in post-mortem studies

Energy Technology Data Exchange (ETDEWEB)

Filograna, Laura [University of Zurich, Department of Forensic Medicine and Imaging, Institute of Forensic Medicine, Zurich (Switzerland); Catholic University of Rome, School of Medicine, University Hospital ' ' A. Gemelli' ' , Department of Radiological Sciences, Rome (Italy); Magarelli, Nicola; Leone, Antonio; Bonomo, Lorenzo [Catholic University of Rome, School of Medicine, University Hospital ' ' A. Gemelli' ' , Department of Radiological Sciences, Rome (Italy); Guggenberger, Roman; Winklhofer, Sebastian [University Hospital Zurich, Institute of Diagnostic and Interventional Radiology, Zurich (Switzerland); Thali, Michael John [University of Zurich, Department of Forensic Medicine and Imaging, Institute of Forensic Medicine, Zurich (Switzerland)

2015-09-15

The aim of this ex vivo study was to assess the performance of monoenergetic dual-energy CT (DECT) reconstructions to reduce metal artefacts in bodies with orthopedic devices in comparison with standard single-energy CT (SECT) examinations in forensic imaging. Forensic and clinical impacts of this study are also discussed. Thirty metallic implants in 20 consecutive cadavers with metallic implants underwent both SECT and DECT with a clinically suitable scanning protocol. Extrapolated monoenergetic DECT images at 64, 69, 88, 105, 120, and 130 keV and individually adjusted monoenergy for optimized image quality (OPTkeV) were generated. Image quality of the seven monoenergetic images and of the corresponding SECT image was assessed qualitatively and quantitatively by visual rating and measurements of attenuation changes induced by streak artefact. Qualitative and quantitative analyses showed statistically significant differences between monoenergetic DECT extrapolated images and SECT, with improvements in diagnostic assessment in monoenergetic DECT at higher monoenergies. The mean value of OPTkeV was 137.6 ± 4.9 with a range of 130 to 148 keV. This study demonstrates that monoenergetic DECT images extrapolated at high energy levels significantly reduce metallic artefacts from orthopedic implants and improve image quality compared to SECT examination in forensic imaging. (orig.)

Value of monoenergetic dual-energy CT (DECT) for artefact reduction from metallic orthopedic implants in post-mortem studies

International Nuclear Information System (INIS)

Filograna, Laura; Magarelli, Nicola; Leone, Antonio; Bonomo, Lorenzo; Guggenberger, Roman; Winklhofer, Sebastian; Thali, Michael John

2015-01-01

The aim of this ex vivo study was to assess the performance of monoenergetic dual-energy CT (DECT) reconstructions to reduce metal artefacts in bodies with orthopedic devices in comparison with standard single-energy CT (SECT) examinations in forensic imaging. Forensic and clinical impacts of this study are also discussed. Thirty metallic implants in 20 consecutive cadavers with metallic implants underwent both SECT and DECT with a clinically suitable scanning protocol. Extrapolated monoenergetic DECT images at 64, 69, 88, 105, 120, and 130 keV and individually adjusted monoenergy for optimized image quality (OPTkeV) were generated. Image quality of the seven monoenergetic images and of the corresponding SECT image was assessed qualitatively and quantitatively by visual rating and measurements of attenuation changes induced by streak artefact. Qualitative and quantitative analyses showed statistically significant differences between monoenergetic DECT extrapolated images and SECT, with improvements in diagnostic assessment in monoenergetic DECT at higher monoenergies. The mean value of OPTkeV was 137.6 ± 4.9 with a range of 130 to 148 keV. This study demonstrates that monoenergetic DECT images extrapolated at high energy levels significantly reduce metallic artefacts from orthopedic implants and improve image quality compared to SECT examination in forensic imaging. (orig.)

In Vitro Validation of an Artefact Suppression Algorithm in X-Ray Phase-Contrast Computed Tomography.

Science.gov (United States)

Sunaguchi, Naoki; Yuasa, Tetsuya; Hirano, Shin-Ichi; Gupta, Rajiv; Ando, Masami

2015-01-01

X-ray phase-contrast tomography can significantly increase the contrast-resolution of conventional attenuation-contrast imaging, especially for soft-tissue structures that have very similar attenuation. Just as in attenuation-based tomography, phase contrast tomography requires a linear dependence of aggregate beam direction on the incremental direction alteration caused by individual voxels along the path of the X-ray beam. Dense objects such as calcifications in biological specimens violate this condition. There are extensive beam deflection artefacts in the vicinity of such structures because they result in large distortion of wave front due to the large difference of refractive index; for such large changes in beam direction, the transmittance of the silicon analyzer crystal saturates and is no longer linearly dependent on the angle of refraction. This paper describes a method by which these effects can be overcome and excellent soft-tissue contrast of phase tomography can be preserved in the vicinity of such artefact-producing structures.

Minimally destructive DNA extraction from archaeological artefacts made from whale baleen

DEFF Research Database (Denmark)

Sinding, Mikkel Holger Strander; Gilbert, Tom; Grønnow, Bjarne

2012-01-01

Here we demonstrate the successful extraction and amplification of target species DNA from artefacts made of whale baleen collected from excavations of past palaeo-Eskimo and Inuit cultures in Greenland. DNA was successfully extracted and amplified from a single baleen bristle of 1.5 cm length...... genetic studies. We conclude that genetic investigation of historical baleen collections can contribute to our knowledge of the prehistoric population genetics of baleen whales, for example by quantifying the impact of modern whaling on the genetic diversity of bowhead whales....

Laryngeal mask airway (LMA) artefact resulting in MRI misdiagnosis

International Nuclear Information System (INIS)

Schieble, Thomas; Patel, Anuradha; Davidson, Melissa

2008-01-01

We report a 7-year-old child who underwent brain MRI for a known seizure disorder. The technique used for general anesthesia included inhalation induction followed by placement of a laryngeal mask airway (LMA) for airway maintenance. Because the reviewing radiologist was unfamiliar with the use of an LMA during anesthesia, and because the attending anesthesiologist did not communicate his technique to the radiologist, an MRI misdiagnosis was reported because of artefact created by the in situ LMA. As a result of this misdiagnosis the child was subjected to unnecessary subsequent testing to rule out a reported anatomic abnormality induced by the LMA. Our case illustrates the need for coordination of patient care among hospital services. (orig.)

Laryngeal mask airway (LMA) artefact resulting in MRI misdiagnosis

Energy Technology Data Exchange (ETDEWEB)

Schieble, Thomas [University of Medicine and Dentistry of New Jersey, Department of Anesthesiology, New Jersey Medical School, Newark, NJ (United States); Maimonides Medical Center, Department of Anesthesiology, Brooklyn, NY (United States); Patel, Anuradha; Davidson, Melissa [University of Medicine and Dentistry of New Jersey, Department of Anesthesiology, New Jersey Medical School, Newark, NJ (United States)

2008-03-15

We report a 7-year-old child who underwent brain MRI for a known seizure disorder. The technique used for general anesthesia included inhalation induction followed by placement of a laryngeal mask airway (LMA) for airway maintenance. Because the reviewing radiologist was unfamiliar with the use of an LMA during anesthesia, and because the attending anesthesiologist did not communicate his technique to the radiologist, an MRI misdiagnosis was reported because of artefact created by the in situ LMA. As a result of this misdiagnosis the child was subjected to unnecessary subsequent testing to rule out a reported anatomic abnormality induced by the LMA. Our case illustrates the need for coordination of patient care among hospital services. (orig.)

Diffusion-weighted imaging of the liver at 3 T using section-selection gradient reversal: emphasis on chemical shift artefacts and lesion conspicuity

International Nuclear Information System (INIS)

Lee, J.S.; Kim, Y.K.; Jeong, W.K.; Choi, D.; Lee, W.J.

2015-01-01

Aim: To assess the value of section-selection gradient reversal (SSGR) in liver diffusion-weighted imaging (DWI) by comparing it to conventional DWI with an emphasis on chemical shift artefacts and lesion conspicuity. Materials and methods: Forty-eight patients (29 men and 19 women; age range 33–80 years) with 48 liver lesions underwent two DWI examinations using spectral presaturation with inversion recovery fat suppression with and without SSGR at 3 T. Two reviewers evaluated each DWI (b = 100 and b = 800 image) with respect to chemical shift artefacts and liver lesion conspicuity using five-point scales and performed pairwise comparisons between the two DWIs. The signal-to-noise ratio (SNR) of the liver and the lesion and the lesion–liver contrast-to-noise ratio (CNR) were also calculated. Results: SSGR-DWI was significantly better than conventional DWI with respect to chemical shift artefacts and lesion conspicuity in both separate reviews and pairwise comparisons (p < 0.05). There were significant differences in the SNR of the liver (b = 100 and b = 800 images) and lesion (b = 800) between SSGR-DWI and conventional DWI (p < 0.05). Conclusion: Applying the SSGR method to DWI using SPIR fat suppression at 3 T could significantly reduce chemical shift artefacts without incurring additional acquisition time or SNR penalties, which leads to increased conspicuity of focal liver lesions. - Highlights: • Chemical shift artefact in liver DWI is markedly decreased by applying SSGR. • Liver lesion conspicuity is improved by applying SSGR to DWI. • In SNR of the liver, SSGR-DWI is better than conventional DWI

Automated correction of spin-history related motion artefacts in fMRI : Simulated and phantom data

NARCIS (Netherlands)

Muresan, L; Renken, R.; Roerdink, J.B.T.M.; Duifhuis, H.

This paper concerns the problem of correcting spin-history artefacts in fMRI data. We focus on the influence of through-plane motion on the history of magnetization. A change in object position will disrupt the tissue’s steady-state magnetization. The disruption will propagate to the next few

Assessment of filament led bulbs with respect to temporal light artefacts

DEFF Research Database (Denmark)

Lindén, Johannes; Thorseth, Anders; Corell, Dennis Dan

2017-01-01

Temporal light artefacts, abbreviated TLAs (including flicker, stroboscopic effect and phantom arrays), i.e. undesired time modulation in luminance from a light source, has shown to be a threat to wider SSL adoption especially related to dimming functions and low-quality LED products. This is due...... to the effects that both noticeable and unperceivable TLAs have on human perception and wellbeing. In the present work a number of filament LED bulbs, currently available on the market, are assessed primarily with respect to TLAs, but also with respect to photometric, colorimetric and efficiency properties...

Diffusion of heat from a finite, rectangular, plane heat source

International Nuclear Information System (INIS)

Ferreri, J.C.; Caballero, C.H.

1985-01-01

Non-dimensional results for the temperature field originating in a rectangular, finite, plane heat source with infinitesimal thickness are introduced. The source decays in time, zero decay being a particular case. Results are useful for obtaining an aproximation of the maximum temperature of a system holding an internal heat source. The range selected for the parameters is specially useful in the case of a nuclear waste repository. The application to the case of mass diffussion arises from analogy. (Author) [es

A new method to compensate impedance artefacts for Li-ion batteries with integrated micro-reference electrodes

NARCIS (Netherlands)

Raijmakers, L.H.J.; Notten, P.H.L.; Lammers, M.J.G.

2017-01-01

In order to measure the electrochemical characteristics of both electrodes inside Li-ion batteries, micro-reference electrodes (μREF) turned out to be very useful. However, measuring the electrochemical impedance with respect to μREF can lead to severe measurement artefacts, making a detailed

Registration concepts for the just-in-time artefact correction by means of virtual computed tomography

Energy Technology Data Exchange (ETDEWEB)

Kasperl, St.; Franz, M. [Fraunhofer Development Center for X-ray Technology EZRT, a cooperative dept. of the Fraunhofer Institutes IZFP Saarbrucken and IIS Erlangen, Furth (Germany)

2007-07-01

This article deals with the enhancement of accuracy in CT by just-in-time correction of artefacts (beam hardening, scattered radiation) caused by the interaction of X-rays with matter. The so called EAR method needs for simulation a registration of the object. Therefore the article presents two different registration concepts. (authors)

Registration concepts for the just-in-time artefact correction by means of virtual computed tomography

International Nuclear Information System (INIS)

Kasperl, St.; Franz, M.

2007-01-01

This article deals with the enhancement of accuracy in CT by just-in-time correction of artefacts (beam hardening, scattered radiation) caused by the interaction of X-rays with matter. The so called EAR method needs for simulation a registration of the object. Therefore the article presents two different registration concepts. (authors)

Metallic artefact reduction with monoenergetic dual-energy CT: systematic ex vivo evaluation of posterior spinal fusion implants from various vendors and different spine levels.

Science.gov (United States)

Guggenberger, R; Winklhofer, S; Osterhoff, G; Wanner, G A; Fortunati, M; Andreisek, G; Alkadhi, H; Stolzmann, P

2012-11-01

To evaluate optimal monoenergetic dual-energy computed tomography (DECT) settings for artefact reduction of posterior spinal fusion implants of various vendors and spine levels. Posterior spinal fusion implants of five vendors for cervical, thoracic and lumbar spine were examined ex vivo with single-energy (SE) CT (120 kVp) and DECT (140/100 kVp). Extrapolated monoenergetic DECT images at 64, 69, 88, 105 keV and individually adjusted monoenergy for optimised image quality (OPTkeV) were generated. Two independent radiologists assessed quantitative and qualitative image parameters for each device and spine level. Inter-reader agreements of quantitative and qualitative parameters were high (ICC = 0.81-1.00, κ = 0.54-0.77). HU values of spinal fusion implants were significantly different among vendors (P metallic artefacts from implants than SECT. Use of individual keV values for vendor and spine level is recommended. • Artefacts pose problems for CT following posterior spinal fusion implants. • CT images are interpreted better with monoenergetic extrapolation using dual-energy (DE) CT. • DECT extrapolation improves image quality and reduces metallic artefacts over SECT. • There were considerable differences in monoenergy values among vendors and spine levels. • Use of individualised monoenergy values is indicated for different metallic hardware devices.

Preliminary Results of Ocular Artefacts Identification in EEC Series by Neural Network

OpenAIRE

Kofronova, M.

1996-01-01

The human electroencephalogram (EEG), is record of the electrical activity of the brain and contains useful diagnostic information on a variety of neurological disorders. Normal EEG signal are usually registered from electrodes placed on the scalp, and are often very small in amplitude, of 20 µV. The EEG, like all biomedical signals, is very susceptible to a variety of large signal contamination or artefacts (signals of other than brain activity) which reduce its clinical usefulness. For e...

Explorative Materiality and Knowledge. The Role of Creative Exploration and Artefacts in Design Research

Directory of Open Access Journals (Sweden)

Kristina Niedderer

2013-08-01

Full Text Available Juxtaposing the nature of design and the foundations of research in the traditional science and humanities disciplines puts their differences into sharp relief. The comparison highlights the key characteristics of design – its creative and experiential nature – which any design research must take into account, as well as the theoretical foundations of research. The aim of this article is to develop an understanding of the ontological, epistemological and methodological issues of design research, and to offer a framework that can embrace equally the notions of creativity and experiential knowledge, and of academic rigour. Furthermore,the potential roles of the design process and artefact within research are examined within this theoretical framework, which suggests that design processes and artefacts can – if appropriately framed – play an important partin the research process, facilitating an approach commensurate with the aims ofdesign enquiry. A case study of the Niedderer’s own work serves to illustratethe balance and integration of theory and (creative practice within the research process, and how this integration can enable a multi-layered contribution to the theoretical and practical advancement of the field.

Analytical artefacts in the speciation of arsenic in clinical samples

International Nuclear Information System (INIS)

Slejkovec, Zdenka; Falnoga, Ingrid; Goessler, Walter; Elteren, Johannes T. van; Raml, Reingard; Podgornik, Helena; Cernelc, Peter

2008-01-01

Urine and blood samples of cancer patients, treated with high doses of arsenic trioxide were analysed for arsenic species using HPLC-HGAFS and, in some cases, HPLC-ICPMS. Total arsenic was determined with either flow injection-HGAFS in urine or radiochemical neutron activation analysis in blood fractions (in serum/plasma, blood cells). The total arsenic concentrations (during prolonged, daily/weekly arsenic trioxide therapy) were in the μg mL -1 range for urine and in the ng g -1 range for blood fractions. The main arsenic species found in urine were As(III), MA and DMA and in blood As(V), MA and DMA. With proper sample preparation and storage of urine (no preservation agents/storage in liquid nitrogen) no analytical artefacts were observed and absence of significant amounts of alleged trivalent metabolites was proven. On the contrary, in blood samples a certain amount of arsenic can get lost in the speciation procedure what was especially noticeable for the blood cells although also plasma/serum gave rise to some disappearance of arsenic. The latter losses may be attributed to precipitation of As(III)-containing proteins/peptides during the methanol/water extraction procedure whereas the former losses were due to loss of specific As(III)-complexing proteins/peptides (e.g. cysteine, metallothionein, reduced GSH, ferritin) on the column (Hamilton PRP-X100) during the separation procedure. Contemporary analytical protocols are not able to completely avoid artefacts due to losses from the sampling to the detection stage so that it is recommended to be careful with the explanation of results, particularly regarding metabolic and pharmacokinetic interpretations, and always aim to compare the sum of species with the total arsenic concentration determined independently

X-ray microtomography scanner using time-delay integration for elimination of ring artefacts in the reconstructed image

International Nuclear Information System (INIS)

Davis, G.R.; London Univ.; Elliott, J.C.; London Univ.

1997-01-01

Most X-ray microtomography scanners work on the same principle as third-generation medical CT scanners, that is, the same point in each projection is measured by the same detector element. This leads to ring artefacts in the reconstructed image if the X-ray sensitivities of the individual detector elements, after any analytical correction, are not all identical. We have developed an X-ray microtomography scanner which uses the time-delay integration method of imaging with a CCD detector to average the characteristics of all the detector elements in each linear projection together. This has the added advantage of allowing specimens which are larger than the detector and X-ray field to be scanned. The device also uses a novel mechanical stage to ''average out'' inhomogeneities in the X-ray field. The results show that ring artefacts in microtomographic images are eliminated using this technique. (orig.)

Theory of unidirectional spin heat conveyer

Science.gov (United States)

Adachi, Hiroto; Maekawa, Sadamichi

2015-05-01

We theoretically investigate the unidirectional spin heat conveyer effect recently reported in the literature that emerges from the Damon-Eshbach spin wave on the surface of a magnetic material. We develop a simple phenomenological theory for heat transfer dynamics in a coupled system of phonons and the Damon-Eshbach spin wave, and demonstrate that there arises a direction-selective heat flow as a result of the competition between an isotropic heat diffusion by phonons and a unidirectional heat drift by the spin wave. The phenomenological approach can account for the asymmetric local temperature distribution observed in the experiment.

Reduction of CT beam hardening artefacts of ethylene vinyl alcohol copolymer by variation of the tantalum content: evaluation in a standardized aortic endoleak phantom

International Nuclear Information System (INIS)

Treitl, Karla M.; Scherr, Michael; Foerth, Monika; Braun, Franziska; Maxien, Daniel; Treitl, Marcus

2015-01-01

Our aim was to develop an aortic stent graft phantom to simulate endoleak treatment and to find a tantalum content (TC) of ethylene-vinyl-alcohol-copolymer that causes fewer computed tomography (CT) beam hardening artefacts, but still allows for fluoroscopic visualization. Ethylene-vinyl-alcohol-copolymer specimens of different TC (10-50 %, and 100 %) were injected in an aortic phantom bearing a stent graft and endoleak cavities with simulated re-perfusion. Fluoroscopic visibility of the ethylene-vinyl-alcohol-copolymer specimens was analyzed. In addition, six radiologists analyzed endoleak visibility, and artefact intensity of ethylene-vinyl-alcohol-copolymer in CT. Reduction of TC significantly decreased CT artefact intensity of ethylene-vinyl-alcohol-copolymer and increased visibility of endoleak re-perfusion (p < 0.000). It also significantly decreased fluoroscopic visibility of ethylene-vinyl-alcohol-copolymer (R = 0.883, p ≤ 0.01), and increased the active embolic volumes prior to visualization (Δ ≥ 40 μl). Ethylene-vinyl-alcohol-copolymer specimens with a TC of 45-50 % exhibited reasonable visibility, a low active embolic volume and a tolerable CT artefact intensity. The developed aortic stent graft phantom allows for a reproducible simulation of embolization of endoleaks. The data suggest a reduction of the TC of ethylene-vinyl-alcohol-copolymer to 45 -50 % of the original, to interfere less with diagnostic imaging in follow-up CT examinations, while still allowing for fluoroscopic visualization. (orig.)

Comment on “Observations of ammonia, nitric acid, and fine particles in a rural gas production region” by Yi Li, Florian M. Schwandnera, H. James Sewell, Angela Zivkovich, Mark Tigges, Suresh Raja, Stephen Holcomb, John V. Molenar, Lincoln Sherman, Cassie Archuleta, Taehyoung Lee and Jeffrey L. Collett Jr. Atmospheric Environment (in press)

Science.gov (United States)

Phillips, Gavin J.

2014-05-01

An artefact of the detection of nitric acid (HNO3) by denuder methods is discussed. This artefact arises from the likely reaction of dinitrogen pentoxide (N2O5) on the denuder train resulting in the report of some fraction of N2O5 as HNO3.

Decreased CSF-flow artefacts in T2 imaging of the cervical spine with periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER/BLADE)

International Nuclear Information System (INIS)

Ragoschke-Schumm, Andreas; Schmidt, Peter; Mayer, Thomas E.; Schumm, Julia; Reimann, Georg; Mentzel, Hans-Joachim; Kaiser, Werner A.

2011-01-01

The cervical spine is prone to artefacts in T2 MR-imaging due to patient movements and cerebrospinal fluid flow. The periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER/BLADE) acquisition method was developed to reduce motion artefacts. We sought to determine if T2-BLADE is superior to T2-TSE with conventional k-space reading. Twenty-five patients were examined using a 1.5 T MR-scanner. T2-weighted imaging of the cervical spine in sagittal and axial orientation using conventional or BLADE k-space reading was performed. Spinal cord, subarachnoid space, vertebrae and discs were evaluated by two independent observers using a scale from 0 (non-diagnostic) to 3 (excellent). Interobserver correlation was assessed as Cohen's kappa. Results of Mann-Whitney U test with p < 0.05 were regarded as significant. Furthermore, the investigators were asked for subjective evaluation in consensus. Overall interobserver accuracy of κ = 0.91 was obtained. Comparison of sagittal images showed better values for all investigated structures in T2-BLADE: spinal cord (TSE/BLADE: 1.52/2.04; p < 0.001), subarachnoid space (1.36/2.06; p < 0.001) and vertebrae/discs (1.66/2.86; p < 0.001). Comparison of axial images showed better values in T2-BLADE for spinal cord (1.68/1.86; p = 0.149) and vertebrae/discs (1.0/1.96: p < 0.001) while subarachnoid space was better to be evaluated in conventional T2-TSE (1.94/1.12; p < 0.001). In sagittal orientation, motion- and CSF-flow artefacts were reduced in T2-BLADE. In axial orientation, however, CSF-flow artefacts were pronounced in T2-BLADE. The image quality of the sagittal T2-BLADE sequences was significantly better than the T2-TSE and acquired in less time. In axial orientation, increased CSF-flow artefacts may reduce accuracy of structures in the subarachnoid space. (orig.)

Elemental analysis of artefacts - establishing external beam PIXE

International Nuclear Information System (INIS)

Alves, A.; Johnston, P.; Short, R.; Bubb, I.

1999-01-01

The development of an external PIXE facility on the 1 MV Tandetron accelerator at RMIT has led to a wide range of research possibilities. A proton beam, generated inside a vacuum is brought into air via an Au coated Kapton foil exit window (thickness 8μm, diameter 0.35mm). Monitoring of the beam intensity is achieved by detecting backscattered protons from the inside Au coating on the window. Artefacts, which may be too large to be placed inside the vacuum, are positioned in the beamline opposite the exit window. An optical system consisting of a CCD camera, alignment laser and two mirrors allows viewing of a region of the target 10mm x 10mm. This technique provides quantitative analysis of elements in the pigments used in paintings and on ceramics, which is a valuable tool in art conservation and authentication. Application of the technique to a ceramic sample from the historic house 'Viewbank' is described

Comparison of Selected Properties of Shellac Varnish for Restoration and Polyurethane Varnish for Reconstruction of Historical Artefacts

Directory of Open Access Journals (Sweden)

Kristýna Šimůnková

2018-03-01

Full Text Available At present, many historical artefacts and furniture are only reconstructed and not restored. They are preserved in terms of material reparation, but their historical value decreases significantly. This work is focused on the comparison of the resistance of high-gloss polyurethane varnish with traditional shellac varnish. The varnishes were applied to oak wood and exposed to interior artificial accelerated ageing in Xenotest. Before and after ageing, cold liquid-resistance tests were performed on the tested specimens and gloss, colour, and adhesion were also evaluated. The structures of the surfaces were also analysed using a confocal laser scanning microscope. As expected, polyurethane varnish was much more durable than shellac varnish. Interestingly, shellac varnish was fairly resistant to water at the beginning, but this resistance was greatly reduced after artificial accelerated ageing. This illustrates the importance of sheltering the shellac treated artefacts in stable temperature-humidity conditions with the least possible effect of solar radiation.

The use of radiation in the study of cultural heritage artefacts

Science.gov (United States)

Creagh, Dudley; Otieno-Alego, Vincent; Treasure, Alana; Kubik, Maria; Hallam, David

2017-08-01

Patrons of art galleries and museums, tourists visiting historic buildings, and sightseers viewing archaeological sites are generally unaware of the extent to which science and technology has contributed to the value of what they see. Many countries rely on cultural tourism to generate national wealth. The use of radiation of many kinds to assist in the conservation/restoration of cultural heritage artefacts is described in this paper. In particular, the paper will describe studies of the pigments used in historic Australian Indigenous art, the degradation of manuscripts written using iron-gall inks, the protection of statues against corrosion and the selection of lubricants for use in old machinery.

Plasma cleaning and analysis of archeological artefacts from Sipán

Science.gov (United States)

Saettone, E. A. O.; da Matta, J. A. S.; Alva, W.; Chubaci, J. F. O.; Fantini, M. C. A.; Galvão, R. M. O.; Kiyohara, P.; Tabacniks, M. H.

2003-04-01

A novel procedure using plasma sputtering in an electron-cyclotron-resonance device has been applied to clean archeological MOCHE artefacts, unearthed at the Royal Tombs of Sipán. After successful cleaning, the pieces were analysed by a variety of complementary techniques, namely proton-induced x-ray emission, Rutherford backscattering spectroscopy, x-ray diffraction, electron microscopy, and inductively coupled plasma mass spectroscopy. With these techniques, it has been possible to not only determine the profiles of the gold and silver surface layers, but also to detect elements that may be relevant to explain the gilding techniques skillfully developed by the metal smiths of the MOCHE culture.

Human brain receptor autoradiography using whole hemisphere sections: a general method that minimizes tissue artefacts

International Nuclear Information System (INIS)

Quirion, R.; Robitaille, Y.; Martial, J.; Chabot, J.G.; Lemoine, P.; Pilapil, C.; Dalpe, M.

1987-01-01

A general method for the preparation of high-quality, mostly ice-crystal-artefact-free whole human brain hemisphere sections is described. Upon receipt, hemispheres are divided; one is then fixed in buffered 10% formalin for neuropathological analysis while the other is cut in 8-10-mm-thick coronal slices that are then rapidly frozen in 2-methylbutane at -40 degrees C (10-15 sec) before being placed in the brain bank at -80 degrees C. Such rapid freezing markedly decreases the formation of ice-crystal artefacts. Whole-hemisphere 20-micron thick sections are then cut and mounted onto lantern-type gelatin-coated slides. These sections are subsequently used for both qualitative and quantitative in vitro receptor autoradiography. Examples of data obtained are given by using various radioligands labelling classical neutrotransmitter, neuropeptide, enzyme, and ion channel receptor binding sites. This method should be useful for the obtention of various receptor maps in human brain. Such information could be most useful for in vivo receptor visualization studies using positron emission tomography (PET) scanning. It could also indicate if a given receptor population is specifically and selectively altered in certain brain diseases, eventually leading to the development of new therapeutic approaches

Robust motion artefact resistant circuit for calculation of Mean Arterial Pressure from pulse transit time.

Science.gov (United States)

Bhattacharya, Tinish; Gupta, Ankesh; Singh, Salam ThoiThoi; Roy, Sitikantha; Prasad, Anamika

2017-07-01

Cuff-less and non-invasive methods of Blood Pressure (BP) monitoring have faced a lot of challenges like stability, noise, motion artefact and requirement for calibration. These factors are the major reasons why such devices do not get approval from the medical community easily. One such method is calculating Blood Pressure indirectly from pulse transit time (PTT) obtained from electrocardiogram (ECG) and Photoplethysmogram (PPG). In this paper we have proposed two novel analog signal conditioning circuits for ECG and PPG that increase stability, remove motion artefacts, remove the sinusoidal wavering of the ECG baseline due to respiration and provide consistent digital pulses corresponding to blood pulses/heart-beat. We have combined these two systems to obtain the PTT and then correlated it with the Mean Arterial Pressure (MAP). The aim was to perform major part of the processing in analog domain to decrease processing load over microcontroller so as to reduce cost and make it simple and robust. We have found from our experiments that the proposed circuits can calculate the Heart Rate (HR) with a maximum error of ~3.0% and MAP with a maximum error of ~2.4% at rest and ~4.6% in motion.

Steel heat treating: mathematical modelling and numerical simulation of a problem arising in the automotive industry

Directory of Open Access Journals (Sweden)

Jose Manuel Diaz Moreno

2017-12-01

Full Text Available We describe a mathematical model for the industrial heating and cooling processes of a steel workpiece representing the steering rack of an automobile. The goal of steel heat treating is to provide a hardened surface on critical parts of the workpiece while keeping the rest soft and ductile in order to reduce fatigue. The high hardness is due to the phase transformation of steel accompanying the rapid cooling. This work takes into account both heating-cooling stage and viscoplastic model. Once the general mathematical formulation is derived, we can perform some numerical simulations.

Artefact in Physiological Data Collected from Patients with Brain Injury: Quantifying the Problem and Providing a Solution Using a Factorial Switching Linear Dynamical Systems Approach.

Science.gov (United States)

Georgatzis, Konstantinos; Lal, Partha; Hawthorne, Christopher; Shaw, Martin; Piper, Ian; Tarbert, Claire; Donald, Rob; Williams, Christopher K I

2016-01-01

High-resolution, artefact-free and accurately annotated physiological data are desirable in patients with brain injury both to inform clinical decision-making and for intelligent analysis of the data in applications such as predictive modelling. We have quantified the quality of annotation surrounding artefactual events and propose a factorial switching linear dynamical systems (FSLDS) approach to automatically detect artefact in physiological data collected in the neurological intensive care unit (NICU). Retrospective analysis of the BrainIT data set to discover potential hypotensive events corrupted by artefact and identify the annotation of associated clinical interventions. Training of an FSLDS model on clinician-annotated artefactual events in five patients with severe traumatic brain injury. In a subset of 187 patients in the BrainIT database, 26.5 % of potential hypotensive events were abandoned because of artefactual data. Only 30 % of these episodes could be attributed to an annotated clinical intervention. As assessed by the area under the receiver operating characteristic curve metric, FSLDS model performance in automatically identifying the events of blood sampling, arterial line damping and patient handling was 0.978, 0.987 and 0.765, respectively. The influence of artefact on physiological data collected in the NICU is a significant problem. This pilot study using an FSLDS approach shows real promise and is under further development.

Preservation of archaeological artefacts by γ-ray induced polymerization technique

International Nuclear Information System (INIS)

Gueven, O.

1983-01-01

For the preservation and consolidation of archaeological artefacts irradiation of these objects with γ-rays seems to be a very promising method. In situ polymerization of monomers impregnated in the capillaries and cavities of the objects by γ-rays provides a simultaneous sterilization and consolidation effect. In the present work this method of preservation is applied to some XIIth century ceramic findings belonging to Seljuk period found in South-East Anatolia. Monomer impregnation is restricted to the surfaces of the objects. The colored figures and structures which are present but not perceptible on these objects became fully apparent upon polymerizing hydrophilic monomers on their surfaces. Crosslinking of the top polymer layer further provides a permanent protection of the substrate material. (author)

Towards a Knowledge Communication Perspective on Designing Artefacts Supporting Knowledge Work

Directory of Open Access Journals (Sweden)

Niclas Eberhagen

2015-02-01

Full Text Available The designing of computer-based artefacts to support knowledge work is far from a straightforward rational process. Characteristics of knowledge work have a bearing upon how developers (or designers, together with users, come to approach and capture the rich and tacit knowing of the practice. As all knowledge work is about the production of knowledge, transforming it, so is the design practice for developing artefacts to occupy space within that same practice. There is a need for providing a conceptual language to better reflect the nature of this design work that goes beyond those dressed in the managerial (or rational language of planned activities and deliverables. Towards this end, a conceptual frame is presented that makes several important aspects of the design practice visible. The frame brings together both nature of design work and characteristics of knowledge work to extend the frame of knowledge in user-developer communication of Kensing and Munk-Madsen. Thereby, providing a means to focus attention and dress debate on what situated designing is. By using explicit concepts, such as types knowledge domains embedded in the design situation, the transitional paths between them, and design engagements, it arms practitioners with specific linguistic constructs to direct attention and efforts in planning and organizing development undertakings.Purpose – the purpose of this work is to present and argue for a perspective on designing of computer-based artefacts supporting knowledge work. This is done to inform practitioners, directing their attention and dressing debate, and providing a conceptual language to better capture design activities in planning and organizing development undertakings.Design/Methodology/Approach – The approach presented in this article is conceptual in so far that a model or frame providing linguistic constructs is constructed and argued, building upon scholarly work of knowledge communication and drawing upon

Investigations on post-dryout heat transfer in bilaterally heated annular channels

International Nuclear Information System (INIS)

Tian, W.X.; Qiu, S.Z.; Jia, D.N.

2006-01-01

Post-dryout heat transfer in bilaterally heated vertical narrow annular channels with 1.0, 1.5 and 2.0 mm gap size has been experimentally investigated with deionized water under the condition of pressure ranging from 1.38 to 5.9 MPa and low mass flow rate from 42.9 to 150.2 kg/m 2 s. The experimental data was compared with well known empirical correlations including Groeneveld, Mattson, etc., and none of them gave an ideal prediction. Theoretical investigations were also carried out on post-dryout heat transfer in annular channels. Based on analysis of heat exchange processes arising among the droplets, the vapor and two tube walls of annular channel, a non-equilibrium mechanistic heat transfer model was developed. Comparison indicated that the present model prediction showed a good agreement with our experimental data. Theoretical calculation result showed that the forced convective heat transfer between the heated wall and vapor dominate the overall heat transfer. The heat transfer caused by the droplets direct contact to the wall and the interfacial convection/evaporation of droplets in superheated vapors also had an indispensable contribution. The radiation heat transfer would be neglected because of its small contribution (less than 0.11%) to the total heat transfer

Hyoscine butylbromide significantly decreases motion artefacts and allows better delineation of anatomic structures in mp-MRI of the prostate

Energy Technology Data Exchange (ETDEWEB)

Ullrich, T.; Quentin, M.; Schmaltz, A.K.; Rubbert, C.; Blondin, D.; Antoch, G.; Schimmoeller, L. [University Dusseldorf, Medical Faculty, Department of Diagnostic and Interventional Radiology, Dusseldorf (Germany); Arsov, C.; Rabenalt, R.; Albers, P. [University Dusseldorf, Medical Faculty, Department of Urology, Dusseldorf (Germany)

2018-01-15

To prospectively evaluate the effect of hyoscine butylbromide (HBB) on visualisation of anatomical details and motion-related artefacts in mp-MRI of the prostate at 3.0 Tesla. One hundred and three consecutive patients (65 ± 10 years) were included in this trial, powered to demonstrate an improvement of image quality after HBB administration, assessed on a 5-point scale by two blinded readers. All patients received high-spatial resolution axial T2-weighted TSE sequences at 3.0 T without spasmolytic agent, repeated after application of 40 mg HBB and followed by routine mp-MRI. Secondary endpoints were (1) susceptibility to side effects, (2) dependence of spasmolytic effect on patients and acute; weight, and (3) prostate volume. In 68% of patients, HBB significantly improved the anatomic score (mean 3.4 ± 0.9 before and 4.4 ± 0.7 after HBB for both readers, p = <0.001). In 67%, HBB significantly enhanced the artefact score (mean 3.2 ± 1 before and 4.2 ± 0.8 after HBB for reader 1, p = <0.001; 3.2 ± 1 and 4.1 ± 0.8 for reader 2, p = <0.001). Subgroup analysis revealed no statistically significant difference between patients with different bodyweight or prostate volume. Inter-reader agreement was excellent (k = 0.95-0.98). Hyoscine butylbromide significantly improves image quality and reduces motion-related artefacts in mp-MRI of the prostate independent of bodyweight or prostate volume. No side effects were reported. (orig.)

Hyoscine butylbromide significantly decreases motion artefacts and allows better delineation of anatomic structures in mp-MRI of the prostate

International Nuclear Information System (INIS)

Ullrich, T.; Quentin, M.; Schmaltz, A.K.; Rubbert, C.; Blondin, D.; Antoch, G.; Schimmoeller, L.; Arsov, C.; Rabenalt, R.; Albers, P.

2018-01-01

To prospectively evaluate the effect of hyoscine butylbromide (HBB) on visualisation of anatomical details and motion-related artefacts in mp-MRI of the prostate at 3.0 Tesla. One hundred and three consecutive patients (65 ± 10 years) were included in this trial, powered to demonstrate an improvement of image quality after HBB administration, assessed on a 5-point scale by two blinded readers. All patients received high-spatial resolution axial T2-weighted TSE sequences at 3.0 T without spasmolytic agent, repeated after application of 40 mg HBB and followed by routine mp-MRI. Secondary endpoints were (1) susceptibility to side effects, (2) dependence of spasmolytic effect on patients and acute; weight, and (3) prostate volume. In 68% of patients, HBB significantly improved the anatomic score (mean 3.4 ± 0.9 before and 4.4 ± 0.7 after HBB for both readers, p = <0.001). In 67%, HBB significantly enhanced the artefact score (mean 3.2 ± 1 before and 4.2 ± 0.8 after HBB for reader 1, p = <0.001; 3.2 ± 1 and 4.1 ± 0.8 for reader 2, p = <0.001). Subgroup analysis revealed no statistically significant difference between patients with different bodyweight or prostate volume. Inter-reader agreement was excellent (k = 0.95-0.98). Hyoscine butylbromide significantly improves image quality and reduces motion-related artefacts in mp-MRI of the prostate independent of bodyweight or prostate volume. No side effects were reported. (orig.)

Gravel size matters: Early Middle Palaeolithic artefacts made from local Rhine and Meuse deposits in the central Netherlands

NARCIS (Netherlands)

van den Biggelaar, D.F.A.M.; van Balen, R.T.; Kluiving, S.J.; Verpoorte, A.; Alink, A

2016-01-01

The artefact size of the Early Middle Palaeolithic (EMP) assemblages in ice-pushed Rhine–Meuse deposits in the central Netherlands decreases northwestward. This trend correlates to the downstream fining direction of the Rhine–Meuse fluvial system, the source of the rock material, showing that

The usefulness of ultrasound colour-Doppler twinkling artefact for detecting urolithiasis compared with low dose nonenhanced computerized tomography

DEFF Research Database (Denmark)

Winkel, Rikke Rass; Kalhauge, Anna; Fredfeldt, Knud-Erik

2012-01-01

This prospective study evaluates the usefulness of the twinkling artefact (TA) seen on colour-Doppler ultrasound (US) in diagnosing urolithiasis. US and standard computed tomography (CT) were performed blinded on 105 patients. B-mode US and colour-Doppler used separately and in combination showed...

A portable system for acquiring and removing motion artefact from ECG signals

Science.gov (United States)

Griffiths, A.; Das, A.; Fernandes, B.; Gaydecki, P.

2007-07-01

A novel electrocardiograph (ECG) signal acquisition and display system is under development. It is designed for patients ranging from the elderly to athletes. The signals are obtained from electrodes integrated into a vest, amplified, digitally processed and transmitted via Bluetooth to a PC with a Labview ® interface. Digital signal processing is performed to remove movement artefact and electromyographic (EMG) noise, which severely distorts signal morphology and complicates clinical diagnosis. Independent component analysis (ICA) is also used to improve the signal quality. The complete system will integrate the electronics into a single module which will be embedded in the vest.

A portable system for acquiring and removing motion artefact from ECG signals

Energy Technology Data Exchange (ETDEWEB)

Griffiths, A; Das, A; Fernandes, B; Gaydecki, P [School of Electrical and Electronic Engineering, University of Manchester, PO Box 88, Manchester M60 1QD (United Kingdom)

2007-07-15

A novel electrocardiograph (ECG) signal acquisition and display system is under development. It is designed for patients ranging from the elderly to athletes. The signals are obtained from electrodes integrated into a vest, amplified, digitally processed and transmitted via Bluetooth to a PC with a Labview (registered) interface. Digital signal processing is performed to remove movement artefact and electromyographic (EMG) noise, which severely distorts signal morphology and complicates clinical diagnosis. Independent component analysis (ICA) is also used to improve the signal quality. The complete system will integrate the electronics into a single module which will be embedded in the ves000.

Interior lives : the age and interpretation of perishable artefacts from Maori rockshelter sites in inland Otago, New Zealand

International Nuclear Information System (INIS)

Anderson, A.; White, M.; Petchey, F.

2015-01-01

Rockshelter and similar sites in inland Otago have produced a relatively large number of M?ori artefacts made in readily perishable materials such as flax leaves and fibre, tussock grass or tapa (bark) cloth. Regional preservation is clearly related broadly to the relatively arid climate. However, AMS radiocarbon dates on 11 samples from 10 sites shows that while a few date to the 17th century or earlier, the ages of most cluster in the 18th to early 19th centuries. We argue that this represents a phase of accelerated deposition in which material was left behind deliberately, as logistically-determined storage for future use in a strategic plan for exploiting inland resources. We propose that such a process of 'furnishing the landscape' with useful artefacts and stored raw materials became possible when territorial security was achieved by the extension of immigrant tribal authority over the inland region. (author).

Xylem resistance to embolism: presenting a simple diagnostic test for the open vessel artefact.

Science.gov (United States)

Torres-Ruiz, José M; Cochard, Hervé; Choat, Brendan; Jansen, Steven; López, Rosana; Tomášková, Ivana; Padilla-Díaz, Carmen M; Badel, Eric; Burlett, Regis; King, Andrew; Lenoir, Nicolas; Martin-StPaul, Nicolas K; Delzon, Sylvain

2017-07-01

Xylem vulnerability to embolism represents an essential trait for the evaluation of the impact of hydraulics in plant function and ecology. The standard centrifuge technique is widely used for the construction of vulnerability curves, although its accuracy when applied to species with long vessels remains under debate. We developed a simple diagnostic test to determine whether the open-vessel artefact influences centrifuge estimates of embolism resistance. Xylem samples from three species with differing vessel lengths were exposed to less negative xylem pressures via centrifugation than the minimum pressure the sample had previously experienced. Additional calibration was obtained from non-invasive measurement of embolism on intact olive plants by X-ray microtomography. Results showed artefactual decreases in hydraulic conductance (k) for samples with open vessels when exposed to a less negative xylem pressure than the minimum pressure they had previously experienced. X-Ray microtomography indicated that most of the embolism formation in olive occurs at xylem pressures below -4.0 MPa, reaching 50% loss of hydraulic conductivity at -5.3 MPa. The artefactual reductions in k induced by centrifugation underestimate embolism resistance data of species with long vessels. A simple test is suggested to avoid this open vessel artefact and to ensure the reliability of this technique in future studies. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

Heat supply from nuclear power plants

Energy Technology Data Exchange (ETDEWEB)

Stach, V [Ustav Jaderneho Vyzkumu CSKAE, Rez (Czechoslovakia)

1978-05-01

The current state of world power production and consumption is assessed. Prognoses made for the years 1980 to 2000 show that nuclear energy should replace the major part of fossil fuels not only in the production of power but also in the production of heat. In this respect high-temperature reactors are highly prospective. The question is discussed of the technical and economic parameters of dual-purpose heat and power plants. It is, however, necessary to solve problems arising from the safe siting of nuclear heat and power plants and their environmental impacts. The economic benefits of combined power and heat production by such nuclear plants is evident.

Unicompartmental knee arthroplasty MRI: impact of slice-encoding for metal artefact correction MRI on image quality, findings and therapy decision

International Nuclear Information System (INIS)

Agten, Christoph A.; Pfirrmann, Christian W.A.; Sutter, Reto; Grande, Filippo del; Fucentese, Sandro F.; Blatter, Samuel

2015-01-01

To evaluate the impact of slice-encoding for metal artefact correction (SEMAC) on image quality, findings, and therapy decision in patients with unicompartmental knee arthroplasty (UKA). Forty-five painful UKAs were examined at 1.5T-MRI (STIR, proton-density(PD)-weighted sequence, each with SEMAC and high-bandwidth). Artefact size, image quality, anatomic depiction, and clinically relevant findings were compared between SEMAC and high-bandwidth (2 readers). In 30 patients, therapy decision was retrospectively assessed by two orthopaedic surgeons without MRI, with high-bandwidth-MRI, and with SEMAC-MRI. SEMAC reduced mean artefact size for STIR (11.8 cm 2 vs. 37.7 cm 2 ) and PD (16.8 cm 2 vs. 18.9 cm 2 ), p < 0.0005 for both comparisons. SEMAC showed more blurring than high-bandwidth, p < 0.0005. STIR-SEMAC revealed more bone marrow oedema (29 vs. 18 patients, p = 0.001, 30 vs. 13 patients, p < 0.0005, for reader 1 and 2 respectively). PD-SEMAC was worse in detecting meniscal lesions (6 missed, p = 0.031, 9 missed, p = 0.004, by reader 1 and 2 respectively) than PD-high-bandwidth. Revision-surgery was chosen in 12 and 11 patients without MRI (surgeon 1 and 2), with high-bandwidth-MRI in 15 and 14 patients, and with SEMAC-MRI in 19 and 14 patients. STIR-SEMAC was useful in detecting bone marrow oedema and influenced the orthopaedic surgeons' decisions towards surgery, while PD-SEMAC showed no clinical benefit. (orig.)

The role of movies in Norwegiantextbooks. : A study of film as artefact in religious education.

OpenAIRE

Vestøl, Jon Magne

2012-01-01

Drawing on perspectives on educational design, this article investigates the role of movies in Norwegian secondary school textbooks on religious education, including teachers’ handbooks and textbook websites. All passages containing references to films or movies have been included in the analysis. The distribution of references indicates that a film is an optional artefact and that movies are drawn mainly from a Western cinematic tradition and are related to topics such as Christianity and et...

Anatomical studies of timber and EPMA analysis of brass artefacts collected from steam engine shipwreck of Minicoy Island, Lakshadweep, India

Digital Repository Service at National Institute of Oceanography (India)

Tripati, S.; Shukla, S.R.; Som, V.; Sundaresh; Khedekar, V.; Shashikala, S.; Sharma, S.K.

construction but also for anchors. During exploration of shipwreck off Minicoy doorframe hinge, latch, porthole, flanges, J hook were found and all these artefacts are made of brass. Moreover timber remains noticed on doorframe hinge and latch. In order...

Process for extracting residual heat and device for the ultimate absorption of heat for nuclear reactors

International Nuclear Information System (INIS)

Bernard, Lawrence Jr.

1980-01-01

This invention concerns a 'heat sink' or device for the ultimate absorption of heat for electric power stations using the most widespread thermal neutron nuclear reactors, namely 'light water' reactors such as boiling or pressurized water reactors. The residual heat given off by these reactors can be safely extracted with this method by using dry cooling. However, the invention does not concern the problems arising from the cooling of the steam used for actuating the steam turbine nor the cooling of the steam exhausted by the turbine or coming from it, but it does concern the 'safety' part of the nuclear power station in which the residual heat discharged in the reactor is controlled and dissipated [fr

FT-Raman and FT-Infrared investigations of archaeological artefacts from Foeni Neolithic site (Banat, Romania)

OpenAIRE

Simona Cîntă Pînzaru; Dana Pop; Loredana Nemeth

2008-01-01

An impressive collection of chert artefacts from the Foeni Neolithic archaeological site (Timiş County, Banat region, Romania) is hosted by the Banat Museum in Timişoara. A representative set of seven specimens was non-destructively investigated using FT-Raman and ATR-FT-IR spectroscopy. The research was carried out for checking if these readily-available, non-destructive, fast, and cheap methods, which do not require preliminary sample preparation could provide significant information for ch...

Usefulness of IDEAL T2 imaging for homogeneous fat suppression and reducing susceptibility artefacts in brachial plexus MRI at 3.0 T.

Science.gov (United States)

Tagliafico, Alberto; Bignotti, Bianca; Tagliafico, Giulio; Martinoli, Carlo

2016-01-01

To quantitatively and qualitatively compare fat-suppressed MR imaging quality using iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) with that using frequency-selective fat-suppressed (FSFS) T2 images of the brachial plexus at 3.0 T. Prospective MR image analysis was performed in 40 volunteers and 40 patients at a single centre. Oblique-sagittal and coronal IDEAL fat-suppressed T2 images and FSFS T2 images were compared. Visual assessment was performed by two independent musculoskeletal radiologists with respect to: (1) susceptibility artefacts around the neck, (2) homogeneity of fat suppression, (3) image sharpness and (4) tissue resolution contrast of pathologies. The signal-to-noise ratios (SNR) for each image sequence were assessed. Compared to FSFS sequences, IDEAL fat-suppressed T2 images significantly reduced artefacts around the brachial plexus and significantly improved homogeneous fat suppression (p < 0.05). IDEAL significantly improved sharpness and lesion-to-tissue contrast (p < 0.05). The mean SNRs were significantly improved on T2-weighted IDEAL images (p < 0.05). IDEAL technique improved image quality by reducing artefacts around the brachial plexus while maintaining a high SNR and provided superior homogeneous fat suppression than FSFS sequences.

Looking for the Signal: A guide to iterative noise and artefact removal in X-ray tomographic reconstructions of porous geomaterials

Science.gov (United States)

Bruns, S.; Stipp, S. L. S.; Sørensen, H. O.

2017-07-01

X-ray micro- and nanotomography has evolved into a quantitative analysis tool rather than a mere qualitative visualization technique for the study of porous natural materials. Tomographic reconstructions are subject to noise that has to be handled by image filters prior to quantitative analysis. Typically, denoising filters are designed to handle random noise, such as Gaussian or Poisson noise. In tomographic reconstructions, noise has been projected from Radon space to Euclidean space, i.e. post reconstruction noise cannot be expected to be random but to be correlated. Reconstruction artefacts, such as streak or ring artefacts, aggravate the filtering process so algorithms performing well with random noise are not guaranteed to provide satisfactory results for X-ray tomography reconstructions. With sufficient image resolution, the crystalline origin of most geomaterials results in tomography images of objects that are untextured. We developed a denoising framework for these kinds of samples that combines a noise level estimate with iterative nonlocal means denoising. This allows splitting the denoising task into several weak denoising subtasks where the later filtering steps provide a controlled level of texture removal. We describe a hands-on explanation for the use of this iterative denoising approach and the validity and quality of the image enhancement filter was evaluated in a benchmarking experiment with noise footprints of a varying level of correlation and residual artefacts. They were extracted from real tomography reconstructions. We found that our denoising solutions were superior to other denoising algorithms, over a broad range of contrast-to-noise ratios on artificial piecewise constant signals.

Unicompartmental knee arthroplasty MRI: impact of slice-encoding for metal artefact correction MRI on image quality, findings and therapy decision

Energy Technology Data Exchange (ETDEWEB)

Agten, Christoph A.; Pfirrmann, Christian W.A.; Sutter, Reto [Balgrist University Hospital, Radiology Department, Zurich (Switzerland); University of Zurich, Faculty of Medicine, Zurich (Switzerland); Grande, Filippo del [Regional Hospital, Radiology, Lugano (Switzerland); Fucentese, Sandro F.; Blatter, Samuel [University of Zurich, Faculty of Medicine, Zurich (Switzerland); Balgrist University Hospital, Orthopedics, Zurich (Switzerland)

2015-07-15

To evaluate the impact of slice-encoding for metal artefact correction (SEMAC) on image quality, findings, and therapy decision in patients with unicompartmental knee arthroplasty (UKA). Forty-five painful UKAs were examined at 1.5T-MRI (STIR, proton-density(PD)-weighted sequence, each with SEMAC and high-bandwidth). Artefact size, image quality, anatomic depiction, and clinically relevant findings were compared between SEMAC and high-bandwidth (2 readers). In 30 patients, therapy decision was retrospectively assessed by two orthopaedic surgeons without MRI, with high-bandwidth-MRI, and with SEMAC-MRI. SEMAC reduced mean artefact size for STIR (11.8 cm{sup 2} vs. 37.7 cm{sup 2}) and PD (16.8 cm{sup 2} vs. 18.9 cm{sup 2}), p < 0.0005 for both comparisons. SEMAC showed more blurring than high-bandwidth, p < 0.0005. STIR-SEMAC revealed more bone marrow oedema (29 vs. 18 patients, p = 0.001, 30 vs. 13 patients, p < 0.0005, for reader 1 and 2 respectively). PD-SEMAC was worse in detecting meniscal lesions (6 missed, p = 0.031, 9 missed, p = 0.004, by reader 1 and 2 respectively) than PD-high-bandwidth. Revision-surgery was chosen in 12 and 11 patients without MRI (surgeon 1 and 2), with high-bandwidth-MRI in 15 and 14 patients, and with SEMAC-MRI in 19 and 14 patients. STIR-SEMAC was useful in detecting bone marrow oedema and influenced the orthopaedic surgeons' decisions towards surgery, while PD-SEMAC showed no clinical benefit. (orig.)

Quantifying metal artefact reduction using virtual monochromatic dual-layer detector spectral CT imaging in unilateral and bilateral total hip prostheses

NARCIS (Netherlands)

Wellenberg, R. H. H.; Boomsma, M. F.; van Osch, J. A. C.; Vlassenbroek, A.; Milles, J.; Edens, M. A.; Streekstra, G. J.; Slump, C. H.; Maas, M.

2017-01-01

To quantify the impact of prosthesis material and design on the reduction of metal artefacts in total hip arthroplasties using virtual monochromatic dual-layer detector Spectral CT imaging. The water-filled total hip arthroplasty phantom was scanned on a novel 128-slice Philips IQon dual-layer

Primary extradural meningioma arising from the calvarium

Directory of Open Access Journals (Sweden)

N Ravi

2013-06-01

Full Text Available Meningiomas are the most common intracranial tumours. Meningiomas arising at other locations are termed primary extradural meningiomas (EDM and are rare. Here we report a case of EDM arising from the calvarium – a primary calvarial meningioma (PCM.

Application of a Portable XRF Spectrometer for the Non-Invasive analysis of Museum Metal Artefacts

International Nuclear Information System (INIS)

Karydas, A.G.

2007-01-01

The present paper reviews examples of the application of a portable - in house developed- X RF spectrometer for the analysis of museum metal artefacts in Greece. Specific topics are addressed, in particular, to which extent the qualitative or quantitative X RF analyses reveal important information about the raw materials and manufacture techniques used for gold, silver and bronze alloys in antiquity. The analytical information that it is gained by means of the X RF measurements is further assessed in comparison with the existing archaeometallurgical knowledge

Squamous cell carcinoma arising in an odontogenic cyst

International Nuclear Information System (INIS)

Yu, Jae Jung; Hwang, Eui Hwan; Lee, Sang Rae; Choi, Jeong Hee

2003-01-01

Squamous cell carcinoma arising in an odontogenic cyst is uncommon. The diagnosis of carcinoma arising in a cyst requires that there must be an area of microscopic transition from the benign epithelial cyst lining to the invasive squamous cell carcinoma. We report a histopathologically proven case of squamous cell carcinoma arising in a residual mandibular cyst in a 54-year-old woman.

Reducing beam hardening effects and metal artefacts using Medipix3RX: With applications from biomaterial science

OpenAIRE

Rajendran, K.; Walsh, M. F.; de Ruiter, N. J. A.; Chernoglazov, A. I.; Panta, R. K.; Butler, A. P. H.; Butler, P. H.; Bell, S. T.; Anderson, N. G.; Woodfield, T. B. F.; Tredinnick, S. J.; Healy, J. L.; Bateman, C. J.; Aamir, R.; Doesburg, R. M. N.

2013-01-01

This paper discusses methods for reducing beam hardening effects using spectral data for biomaterial applications. A small-animal spectral scanner operating in the diagnostic energy range was used. We investigate the use of photon-processing features of the Medipix3RX ASIC in reducing beam hardening and associated artefacts. A fully operational charge summing mode was used during the imaging routine. We present spectral data collected for metal alloy samples, its analysis using algebraic 3D r...

Solitary Fibrous Tumor Arising from Stomach: CT Findings

Science.gov (United States)

Park, Sung Hee; Kwon, Jieun; Park, Jong-pil; Park, Mi-Suk; Lim, Joon Seok; Kim, Joo Hee; Kim, Ki Whang

2007-01-01

Solitary fibrous tumors are spindle-cell neoplasms that usually develop in the pleura and peritoneum, and rarely arise in the stomach. To our knowledge, there is only one case reporting a solitary fibrous tumor arising from stomach in the English literature. Here we report the case of a 26-year-old man with a large solitary fibrous tumor arising from the stomach which involved the submucosa and muscular layer and resembled a gastrointestinal stromal tumor in the stomach, based on what was seen during abdominal computed tomography. A solitary fibrous tumor arising from the stomach, although rare, could be considered as a diagnostic possibility for gastric submucosal tumors. PMID:18159603

The fission-track analysis: An alternative technique for provenance studies of prehistoric obsidian artefacts

CERN Document Server

Bellot-Gurlet, L; Dorighel, O; Oddone, M; Poupeau, G; Yegingil, Z

1999-01-01

Comparison of fission-track parameters - age and track densities - is an alternative tool for correlating obsidian artefacts with their potential natural sources. This method was applied by different fission-track groups in various regions and results were compared with those obtained using the more popular provenance identification techniques based on chemical composition studies. Hundreds of analyses prove that fission-track dating is a complementary technique which turns out to be very useful, specially when the chemical composition does not fully discriminate different sources. Archaeologically significant results were obtained applying the fission-track analysis in various regions of earth.

The fission-track analysis: An alternative technique for provenance studies of prehistoric obsidian artefacts

International Nuclear Information System (INIS)

Bellot-Gurlet, L.; Bigazzi, G.; Dorighel, O.; Oddone, M.; Poupeau, G.; Yegingil, Z.

1999-01-01

Comparison of fission-track parameters - age and track densities - is an alternative tool for correlating obsidian artefacts with their potential natural sources. This method was applied by different fission-track groups in various regions and results were compared with those obtained using the more popular provenance identification techniques based on chemical composition studies. Hundreds of analyses prove that fission-track dating is a complementary technique which turns out to be very useful, specially when the chemical composition does not fully discriminate different sources. Archaeologically significant results were obtained applying the fission-track analysis in various regions of earth

How could the Viking Sun compass be used with sunstones before and after sunset? Twilight board as a new interpretation of the Uunartoq artefact fragment.

Science.gov (United States)

Bernáth, Balázs; Farkas, Alexandra; Száz, Dénes; Blahó, Miklós; Egri, Adám; Barta, András; Akesson, Susanne; Horváth, Gábor

2014-06-08

Vikings routinely crossed the North Atlantic without a magnetic compass and left their mark on lands as far away as Greenland, Newfoundland and Baffin Island. Based on an eleventh-century dial fragment artefact, found at Uunartoq in Greenland, it is widely accepted that they sailed along chosen latitudes using primitive Sun compasses. Such instruments were tested on sea and proved to be efficient hand-held navigation tools, but the dimensions and incisions of the Uunartoq find are far from optimal in this role. On the basis of the sagas mentioning sunstones, incompatible hypotheses were formed for Viking solar navigation procedures and primitive skylight polarimetry with dichroic or birefringent crystals. We describe here a previously unconceived method of navigation based on the Uunartoq artefact functioning as a 'twilight board', which is a combination of a horizon board and a Sun compass optimized for use when the Sun is close to the horizon. We deduced an appropriate solar navigation procedure using a twilight board, a shadow-stick and birefringent crystals, which bring together earlier suggested methods in harmony and provide a true skylight compass function. This could have allowed Vikings to navigate around the clock, to use the artefact dial as a Sun compass during long parts of the day and to use skylight polarization patterns in the twilight period. In field tests, we found that true north could be appointed with such a medieval skylight compass with an error of about ±4° when the artificially occluded Sun had elevation angles between +10° and -8° relative to the horizon. Our interpretation allows us to assign exact dates to the gnomonic lines on the artefact and outlines the schedule of the merchant ships that sustained the Viking colony in Greenland a millennium ago.

The characterization of artefacts of cultural heritage significance using physical techniques

International Nuclear Information System (INIS)

Creagh, D.C.

2005-01-01

All societies attempt to preserve their cultural heritage because it is this that gives them their identity. How artefacts are identified as being of significance to society, and how to preserve these for posterity, depend on the sophistication of those societies, their wealth, and the determination of members of the societies to preserve their past. If conservation or restoration measures are being undertaken complex analytical experiments must be undertaken beforehand to ensure that the work is being undertaken in an appropriate manner. These investigations may employ electromagnetic (IR, VIS, UV, X-ray, γ-ray) or particulate (electron, proton, neutron, and ion beams) radiation. The use of many of these techniques is described in this paper in experiments on Australian Aboriginal bark paintings, a suit of armour belonging to a famous Australian outlaw, and the degradation of colour motion picture film

Dynamic miniature lighting system with low correlated colour temperature and high colour rendering index for museum lighting of fragile artefacts

DEFF Research Database (Denmark)

Thorseth, Anders; Corell, Dennis Dan; Poulsen, Peter Behrensdorff

2013-01-01

of historical artefacts in display cases at museums and other exhibitions, which can replace 3-5 Watt incandescent light bulbs with a correlated colour temperature (CCT) from 2000 K to 2400 K. The solution decreases the energy consumption by up to 80 %, while maintaining colour rendering indices (Ra) above 90...

District heating

International Nuclear Information System (INIS)

Hansen, L.

1993-01-01

The environmental risks and uncertainties of a high-energy future are disturbing and give rise to several reservations concerning the use of fossil fuels. A number of technologies will help to reduce atmospheric pollution. In Denmark special importance is attached to the following: Energy conservation. Efficient energy conversion. Renewable energy sources. District heating, combined production of heat and power. Many agree that district heating (DH), produced by the traditional heat-only plant, and combined heat and power (CHP) have enormous potential when considering thermal efficiency and lowered environmental impacts: The basic technology of each is proven, it would be relatively simple to satisfy a substantial part of the energy demand, and their high efficiencies mean reduced pollution including greenhouse gas emissions. This is especially important in high population density areas - the obviously preferred sites for such energy generation. Compared with individual heating DH can provide a community with an operationally efficient and most often also an economically competitive heat supply. This is particularly true under the circumstances where the DH system is supplied from CHP plants. Their use results in very substantial improvements in overall efficiency. Further environmental improvements arise from the reduced air pollution obtainable in reasonably large CHP plants equipped with flue gas cleaning to remove particles, sulphur dioxide, and nitrogen acids. As a consequence of these considerations, DH plays an important role in fulfilling the space and water heating demand in many countries. This is especially the case in Denmark where this technology is utilised to a very great extent. Indeed, DH is one of the reasons why Denmark has relatively good air quality in the cities. (au)

Wilms tumor arising in extracoelomic paravertebral soft tissues.

LENUS (Irish Health Repository)

Mulligan, Linda

2012-02-01

Extrarenal Wilms tumor (ERWT) is a well-established entity which most commonly arises within the genitourinary tract, including intracoelomic paranephric soft tissue. Rarely, ERWT arises within teratoma, and it tends to occur predominantly in distinct settings, such as females with spinal defects and males with testicular teratomas. We report a unique ERWT arising within an extracoelomic teratoma of the paraspinal musculature, thereby expanding the range of reported locations for this unusual tumor.

Insular artefacts from Viking-Age burials from mid-Norway. A review of contact between Trøndelag and Britain and Ireland

Directory of Open Access Journals (Sweden)

Aina Margrethe Heen-Pettersen

2014-12-01

Full Text Available This article presents a detailed overview of the Insular artefacts found in Viking-Age burials from the Trøndelag region of mid-Norway, most of which have not previously been published in English. The archaeological evidence indicates that contact between Trøndelag and the British Isles was well established at an early stage of the Viking Age. The main evidence for contact comes from the 9th century, when a number of significant patterns can be discerned. Some local concentrations of Insular goods show the continuing importance of some pre-Viking centres, while other areas suggest co-operation between several neighbouring families in order to equip and provision overseas expeditions. Later, the datable Insular artefacts indicate significant changes in the nature of contact. North Sea trading towards the end of the Viking Age appears to be affected by increasing centralisation of power in Trøndelag during the 10th century.

A single-probe heat pulse method for estimating sap velocity in trees.

Science.gov (United States)

López-Bernal, Álvaro; Testi, Luca; Villalobos, Francisco J

2017-10-01

Available sap flow methods are still far from being simple, cheap and reliable enough to be used beyond very specific research purposes. This study presents and tests a new single-probe heat pulse (SPHP) method for monitoring sap velocity in trees using a single-probe sensor, rather than the multi-probe arrangements used up to now. Based on the fundamental conduction-convection principles of heat transport in sapwood, convective velocity (V h ) is estimated from the temperature increase in the heater after the application of a heat pulse (ΔT). The method was validated against measurements performed with the compensation heat pulse (CHP) technique in field trees of six different species. To do so, a dedicated three-probe sensor capable of simultaneously applying both methods was produced and used. Experimental measurements in the six species showed an excellent agreement between SPHP and CHP outputs for moderate to high flow rates, confirming the applicability of the method. In relation to other sap flow methods, SPHP presents several significant advantages: it requires low power inputs, it uses technically simpler and potentially cheaper instrumentation, the physical damage to the tree is minimal and artefacts caused by incorrect probe spacing and alignment are removed. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

The use of dielectric heating in particulate bed dryout experiments

International Nuclear Information System (INIS)

Stevens, G.F.; Willshire, S.J.

1984-09-01

Decay-heated, liquid-saturated debris beds arise in hypothetical severe accidents with LMFBR and PWR, and a large international effort is currently engaged in experimental studies of the cooling limitations of such beds. Dryout is one of the important cooling limitations. Dielectric heating offers a means of closely simulating decay heating in beds of irregular particles, and is under development at AEE Winfrith for application to experimental studies of dryout. This report describes progress to date. (author)

Esophageal leiomyoma arising in an epiphrenic diverticulum

International Nuclear Information System (INIS)

Hamilton, S.

1988-01-01

A 32-year old woman was found at surgery to have an esophageal leiomyoma arising within an epiphrenic diverticulum. These uncommon conditions may rarely occur together, causing difficulty in diagnosis of the leiomyoma. Other neoplasms may also arise in an epiphrenic diverticulum and should be borne in mind in this situation. (orig.)

The social construction of facts and artefacts: or How the sociology of science and the sociology of technology might benefit each other

NARCIS (Netherlands)

Pinch, Trevor J.; Bijker, Wiebe E.

1984-01-01

The need for an integrated social constructivist approach towards the study of science and technology is outlined. Within such a programme both scientific facts and technological artefacts are to be understood as social constructs. Literature on the sociology of science, the science-technology

EVALUATING AND REFINING THE ‘ENTERPRISE ARCHITECTURE AS STRATEGY’ APPROACH AND ARTEFACTS

Directory of Open Access Journals (Sweden)

M. De Vries

2012-01-01

Full Text Available

ENGLISH ABSTRACT: Enterprise Architecture (EA is a new discipline that has emerged from the need to create a holistic view of an enterprise, and thereby to discover business/IT integration and alignment opportunities across enterprise structures. Previous EA value propositions that merely focus on IT cost reductions will no longer convince management to invest in EA. Today, EA should enable business strategy in the organisation to create value. This resides in the ability to do enterprise optimisation through process standardisation and integration. In order to do this, a new approach is required to integrate EA into the strategy planning process of the organisation.
This article explores the use of three key artefacts – operating models, core diagrams, and an operating maturity assessment as defined by Ross, Weill & Robertson [1] – as the basis of this new approach. Action research is applied to a research group to obtain qualitative feedback on the practicality of the artefacts.

AFRIKAANSE OPSOMMING: Ondernemingsargitektuur (OA is ’n nuwe dissipline wat ontstaan het uit die behoefte om ’n holistiese perspektief van ’n onderneming te skep om sodoende besigheid/IT-integrasie en - belyningsgeleenthede regoor ondernemingstrukture te ontdek. Vorige OA waardeaanbiedings wat hoofsaaklik gefokus het op IT kostebesparings sal bestuur nie meer kan oorreed om in OA te belê nie. Vandag behoort OA bevoegdheid te gee aan ondernemingstrategie om werklik waarde te skep. Hierdie bevoegdheid lê gesetel in ondernemingsoptimering deur middel van prosesstandaardisasie en -integrasie. ’n Nuwe benadering word benodig ten einde OA te integreer met die strategiese beplanningsproses van die organisasie.
Hierdie artikel ondersoek die gebruik van drie artefakte – operasionele modelle, kerndiagramme, en operasionele volwassenheidsassessering soos gedefinieer deur Ross, Weill & Robertson [1] – as die basis van hierdie nuwe benadering

Correction of motion artefacts and pseudo colour visualization of multispectral light scattering images for optical diagnosis of rheumatoid arthritis

Science.gov (United States)

Minet, Olaf; Scheibe, Patrick; Beuthan, Jürgen; Zabarylo, Urszula

2010-02-01

State-of-the-art image processing methods offer new possibilities for diagnosing diseases using scattered light. The optical diagnosis of rheumatism is taken as an example to show that the diagnostic sensitivity can be improved using overlapped pseudo-coloured images of different wavelengths, provided that multispectral images are recorded to compensate for any motion related artefacts which occur during examination.

Protection of metal artefacts with the formation of metal-oxalates complexes by Beauveria bassiana.

Directory of Open Access Journals (Sweden)

Edith eJoseph

2012-01-01

Full Text Available Several fungi present high tolerance to toxic metals and some are able to transform metals into metal-oxalate complexes. In this study, the ability of Beauveria bassiana to produce copper oxalates was evaluated in vitro. Growth performance was tested on various copper-containing media. B. bassiana proved highly resistant to copper, tolerating concentrations of up to 20 g.L-1, and precipitating copper oxalates on all media tested. Chromatographic analyses showed that this species produced oxalic acid as sole metal chelator. The production of metal-oxalates can be used in the restoration and conservation of archaeological and modern metal artefacts. The production of copper-oxalates was confirmed directly using metallic pieces (both archaeological and modern. The conversion of corrosion products into copper oxalates was demonstrated as well. In order to assess whether the capability of B. bassiana to produce metal-oxalates could be applied to other metals, iron and silver were tested as well. Iron appears to be directly sequestered in the wall of the fungal hyphae forming oxalates and probably goethite. However, the formation of a homogeneous layer on the object is not yet optimal. Silver nitrate was extracellularly reduced into nanoparticles of elemental silver by an unknown mechanism. The production of copper oxalates is immediately applicable for the conservation of copper-based artefacts. For iron and silver this is not yet the case. However, the vast ability of B. bassiana to transform toxic metals using different immobilization mechanisms seems to offer considerable possibilities for industrial applications, such as the bioremediation of contaminated soils or the green synthesis of chemicals.

Solitary Fibrous Tumor Arising from Stomach: CT Findings

OpenAIRE

Park, Sung Hee; Kim, Myeong-Jin; Kwon, Jieun; Park, Jong-pil; Park, Mi-Suk; Lim, Joon Seok; Kim, Joo Hee; Kim, Ki Whang

2007-01-01

Solitary fibrous tumors are spindle-cell neoplasms that usually develop in the pleura and peritoneum, and rarely arise in the stomach. To our knowledge, there is only one case reporting a solitary fibrous tumor arising from stomach in the English literature. Here we report the case of a 26-year-old man with a large solitary fibrous tumor arising from the stomach which involved the submucosa and muscular layer and resembled a gastrointestinal stromal tumor in the stomach, based on what was see...

Heat recovery from sorbent-based CO.sub.2 capture

Science.gov (United States)

Jamal, Aqil; Gupta, Raghubir P

2015-03-10

The present invention provides a method of increasing the efficiency of exothermic CO.sub.2 capture processes. The method relates to withdrawing heat generated during the exothermic capture of CO.sub.2 with various sorbents via heat exchange with a working fluid. The working fluid is provided at a temperature and pressure such that it is in the liquid state, and has a vaporization temperature in a range such that the heat arising from the reaction of the CO.sub.2 and the sorbent causes a phase change from liquid to vapor state in whole or in part and transfers heat from to the working fluid. The resulting heated working fluid may subsequently be used to generate power.

A micro-invasive approach using INAA for new insights into Palaeolithic flint archaeological artefacts

International Nuclear Information System (INIS)

Prudencio, M.I.; Dias, M.I.; Marques, R.; Roldan, C.; Aleix Eixea; Villaverde, V.

2016-01-01

Instrumental neutron activation analysis of small flakes from the same flint fragment of archaeological artefacts from Palaeolithic sites ('Abrigo de la Quebrada', 'Cova de les Cendres' and 'Cova Negra'), and eological sour ces (Chelva, Valencia, and Alcoi, Alicante) from the eastern Spain, was performed. The chemical contents of 27 elements were obtained. Ga, Ce, Nd, Yb, Zr and Hf were discarded due to high variations within the same fragment. The identification of chemical fingerprints within heterogeneous flint fragments was able to differentiate flint types and variants ('Domeno' and 'Serreta'), contributing to provenance and human mobility in ancient times. (author)

Quantitative assessment of chemical artefacts produced by propionylation of histones prior to mass spectrometry analysis.

Science.gov (United States)

Soldi, Monica; Cuomo, Alessandro; Bonaldi, Tiziana

2016-07-01

Histone PTMs play a crucial role in regulating chromatin structure and function, with impact on gene expression. MS is nowadays widely applied to study histone PTMs systematically. Because histones are rich in arginine and lysine, classical shot-gun approaches based on trypsin digestion are typically not employed for histone modifications mapping. Instead, different protocols of chemical derivatization of lysines in combination with trypsin have been implemented to obtain "Arg-C like" digestion products that are more suitable for LC-MS/MS analysis. Although widespread, these strategies have been recently described to cause various side reactions that result in chemical modifications prone to be misinterpreted as native histone marks. These artefacts can also interfere with the quantification process, causing errors in histone PTMs profiling. The work of Paternoster V. et al. is a quantitative assessment of methyl-esterification and other side reactions occurring on histones after chemical derivatization of lysines with propionic anhydride [Proteomics 2016, 16, 2059-2063]. The authors estimate the effect of different solvents, incubation times, and pH on the extent of these side reactions. The results collected indicate that the replacement of methanol with isopropanol or ACN not only blocks methyl-esterification, but also significantly reduces other undesired unspecific reactions. Carefully titrating the pH after propionic anhydride addition is another way to keep methyl-esterification under control. Overall, the authors describe a set of experimental conditions that allow reducing the generation of various artefacts during histone propionylation. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Primary extradural meningioma arising from the calvarium | Ravi ...

African Journals Online (AJOL)

Meningiomas are the most common intracranial tumours. Meningiomas arising at other locations are termed primary extradural meningiomas (EDMs) and are rare. Here we report a case of EDM arising from the calvarium – a primary calvarial meningioma (PCM).

Gas in the heat market

Energy Technology Data Exchange (ETDEWEB)

Eckert, L

1981-02-01

An explanation of the various ideas about market delimitations (heat market - gas market) and of the competitive and legal situation is followed by a description of the market situation for gas in the sectors industry and household, commerce and trade. Opportunities available for gase are pointed out by listing the most important substitute energy sources for piped gas in the different fields of application. On the issue of conversion costs being an obstacle to substitution or competition, a few examples are given of the ration of conversion costs to fuel costs arising in industrial firms. A number of economic evaluations are made concerning the utilization of gas in space heating systems.

Ross filter pairs for metal artefact reduction in x-ray tomography: a case study based on imaging and segmentation of metallic implants

Science.gov (United States)

Arhatari, Benedicta D.; Abbey, Brian

2018-01-01

Ross filter pairs have recently been demonstrated as a highly effective means of producing quasi-monoenergetic beams from polychromatic X-ray sources. They have found applications in both X-ray spectroscopy and for elemental separation in X-ray computed tomography (XCT). Here we explore whether they could be applied to the problem of metal artefact reduction (MAR) for applications in medical imaging. Metal artefacts are a common problem in X-ray imaging of metal implants embedded in bone and soft tissue. A number of data post-processing approaches to MAR have been proposed in the literature, however these can be time-consuming and sometimes have limited efficacy. Here we describe and demonstrate an alternative approach based on beam conditioning using Ross filter pairs. This approach obviates the need for any complex post-processing of the data and enables MAR and segmentation from the surrounding tissue by exploiting the absorption edge contrast of the implant.

Apneic oxygenation for elimination of respiratory motion artefact in an intubated patient undergoing helical chest computed tomography angiography.

Directory of Open Access Journals (Sweden)

Ioannis Pneumatikos

2008-10-01

Full Text Available Respiratory motion artifact in intubated and mechanically ventilated patients often reduces the quality of helical computed tomography pulmonary angiography (CTPA. Apneic oxygenation is a well established intra-operative technique that allows adequate oxygenation for short periods (up to 10 min in sedated and paralyzed patients. We describe the use of the apneic oxygenation for elimination of respiratory motion artefact in an intubated patient undergoing helical chest computed tomography angiography.

Metallic artefact reduction with monoenergetic dual-energy CT: systematic ex vivo evaluation of posterior spinal fusion implants from various vendors and different spine levels

Energy Technology Data Exchange (ETDEWEB)

Guggenberger, R.; Winklhofer, S.; Andreisek, G.; Alkadhi, H.; Stolzmann, P. [University Hospital Zurich, Institute of Diagnostic and Interventional Radiology, Zurich (Switzerland); Osterhoff, G.; Wanner, G.A. [University Hospital Zurich, Department of Surgery, Division of Trauma Surgery, Zurich (Switzerland); Fortunati, M. [The Spine Center, Thun (Switzerland)

2012-11-15

To evaluate optimal monoenergetic dual-energy computed tomography (DECT) settings for artefact reduction of posterior spinal fusion implants of various vendors and spine levels. Posterior spinal fusion implants of five vendors for cervical, thoracic and lumbar spine were examined ex vivo with single-energy (SE) CT (120 kVp) and DECT (140/100 kVp). Extrapolated monoenergetic DECT images at 64, 69, 88, 105 keV and individually adjusted monoenergy for optimised image quality (OPTkeV) were generated. Two independent radiologists assessed quantitative and qualitative image parameters for each device and spine level. Inter-reader agreements of quantitative and qualitative parameters were high (ICC = 0.81-1.00, {kappa} = 0.54-0.77). HU values of spinal fusion implants were significantly different among vendors (P < 0.001), spine levels (P < 0.01) and among SECT, monoenergetic DECT of 64, 69, 88, 105 keV and OPTkeV (P < 0.01). Image quality was significantly (P < 0.001) different between datasets and improved with higher monoenergies of DECT compared with SECT (V = 0.58, P < 0.001). Artefacts decreased significantly (V = 0.51, P < 0.001) at higher monoenergies. OPTkeV values ranged from 123-141 keV. OPTkeV according to vendor and spine level are presented herein. Monoenergetic DECT provides significantly better image quality and less metallic artefacts from implants than SECT. Use of individual keV values for vendor and spine level is recommended. (orig.)

Stone heat treatment in the Early Mesolithic of southwestern Germany: Interpretation and identification.

Directory of Open Access Journals (Sweden)

Patrick Schmidt

Full Text Available The Early Mesolithic of southwestern Germany, the so-called Beuronian (9600-7100 BC, is a period of important transformations in the way people lived, in their subsistence and in the stone tools they produced. One of the perhaps most spectacular re-inventions of that time is heat treatment of stones prior to their manufacture into tools. Although heat treatment has been understood as one of the defining characteristics of the Beuronian of southwestern Germany, and although its existence has been known for almost 30 years now, relatively few systematic studies on it are available. In this paper, we present such a study, aiming to shed light on two questions: (1 what technique and heating parameters were used in the Beuronian and (2 how reliable are the macroscopic proxies traditionally used to identify heat treatment in this context? We investigate these questions using a non-destructive archaeometric technique for measuring past heating temperatures of heat-treated stones and a quantitative surface roughness analysis aiming to understand the relations between surface aspect and heat treatment. These methods are applied to 46 Jurassic chert artefacts from the site Helga-Abri located in the Swabian Alb region of southwestern Germany. Our results document that an opportunistic low-investment procedure was used to heat stone, probably relying on the use of the above-ground part of regular camp-fires. We also found that the traditionally used macroscopic criteria, such as colour and surface gloss, cannot be unambiguously used to identify heat treatment in assemblages made from Jurassic chert. These findings have important implications for our understanding of the Beuronian lithic chaîne opératoire in terms of the investment in time and resources necessary, and for the refinement of archaeological techniques used to identify heat treatment in the Mesolithic of the Swabian Alb.

Stone heat treatment in the Early Mesolithic of southwestern Germany: Interpretation and identification.

Science.gov (United States)

Schmidt, Patrick; Spinelli Sanchez, Océane; Kind, Claus-Joachim

2017-01-01

The Early Mesolithic of southwestern Germany, the so-called Beuronian (9600-7100 BC), is a period of important transformations in the way people lived, in their subsistence and in the stone tools they produced. One of the perhaps most spectacular re-inventions of that time is heat treatment of stones prior to their manufacture into tools. Although heat treatment has been understood as one of the defining characteristics of the Beuronian of southwestern Germany, and although its existence has been known for almost 30 years now, relatively few systematic studies on it are available. In this paper, we present such a study, aiming to shed light on two questions: (1) what technique and heating parameters were used in the Beuronian and (2) how reliable are the macroscopic proxies traditionally used to identify heat treatment in this context? We investigate these questions using a non-destructive archaeometric technique for measuring past heating temperatures of heat-treated stones and a quantitative surface roughness analysis aiming to understand the relations between surface aspect and heat treatment. These methods are applied to 46 Jurassic chert artefacts from the site Helga-Abri located in the Swabian Alb region of southwestern Germany. Our results document that an opportunistic low-investment procedure was used to heat stone, probably relying on the use of the above-ground part of regular camp-fires. We also found that the traditionally used macroscopic criteria, such as colour and surface gloss, cannot be unambiguously used to identify heat treatment in assemblages made from Jurassic chert. These findings have important implications for our understanding of the Beuronian lithic chaîne opératoire in terms of the investment in time and resources necessary, and for the refinement of archaeological techniques used to identify heat treatment in the Mesolithic of the Swabian Alb.

Long distance transmission of low grade heat

International Nuclear Information System (INIS)

Arnott, P.T.W.

1977-01-01

This paper is concerned with low and medium temperature water carried by pipeline as a heat transfer medium for the purpose of utilising the waste heat arising from the nuclear power generation process. Different pipelines, single and double, and alternative pipe materials to steel are presented. Later in the paper the effect of the sending-end temperature on the viability of a water pipeline transmission system is discussed and the consequences of using small quantities of steam in order to boost the water temperature are explained. (M.S.)

The present state of research into plasma heating and injection methods

International Nuclear Information System (INIS)

1974-12-01

The advantages and disadvantages recognized by the Advisory Group on Heating and injection for twelve plasma heating and injection methods currently under investigation in Europe are related. The heating and injection requirements of four reference reactor designs are previously defined. The problems which arise when one attempts to extrapolate existing work towards the reactor goal are emphasized. Two refuelling methods not directly linked with the heating problem are discussed. The experiments in operation or under construction in Europe in which each method is investigated are listed. Sixteen working papers which served as a basis for the Advisory Group discussion and which cover all the heating and injection methods examined are included

Effect of radiation heat transfer on the performance of high temperature heat exchanger, (2)

International Nuclear Information System (INIS)

Yamada, Yukio; Mori, Yasuo; Hijikata, Kunio.

1977-01-01

In high temperature helium gas-cooled reactors, the nuclear energy can be utilized effectively, and the safety is excellent as compared with conventional reactors. They are advantageous also in view of environmental problems. In this report, the high temperature heat exchanger used for heating steam with the helium from a high temperature gas reactor is modeled, and the case that radiating gas flow between parallel plates is considered. Analysis was made on the case of one channel and constant heat flux and on the model for a counter-flow type heat exchanger with two channels, and the effect of radiation on the heat transfer in laminar flow and turbulent flow regions was clarified theoretically. The basic equations, the method of approximate solution and the results of calculation are explained. When one dimensional radiation was considered, the representative temperature Tr regarding fluid radiation was introduced, and its relation to mean mixing temperature Tm was determined. It was clarified that the large error in the result did not arise even if Tr was taken equally to Tm, especially in case of turbulent flow. The error was practically negligible when the rate of forced convection heat transfer in case of radiating medium flow was taken same as that in the case without radiation. (Kako, I.)

Stability of retained austenite arising at low temperatures in low carbon steels with copper using TRIP effect

International Nuclear Information System (INIS)

Michta, G.; Pietrzyk, J.; Osuch, W.; Kruk, A.

2003-01-01

The magnetometric measurement results of decomposition of retained austenite arising during low temperature bainite transformation, obtained structure and mechanical properties are presented. Presented results demonstrate that the low temperature bainite transformation leads to formation of two kinds of retained austenite with different stability. Decomposition of low stability retained austenite was observed during cooling to -196 o C, the second with high stability was decomposed only during heating up to 560 o C. The first one was observed in microstructure as big grains and the second more refinement in structure was localised between bainitic regions. (author)

Analysis of artefacts and detail resolution of lung MRI with breath-hold T1-weighted gradient-echo and T2-weighted fast spin-echo sequences with respiratory triggering

International Nuclear Information System (INIS)

Biederer, J.; Reuter, M.; Both, M.; Grimm, J.; Heller, M.; Muhle, C.; Graessner, J.

2002-01-01

The aim of this study was to evaluate feasibility and limitations of two MR sequences for imaging of the lung using a semi-quantitative rating scale. Ten healthy volunteers were assessed with a breath-hold T1-weighted gradient-recalled-echo (TR/TE=129/2.2 ms, matrix 173 x 256) and a T2-weighted turbo spin-echo (TSE) sequence with respiratory triggering (TR/TE=3000-5000/120 ms, matrix 270 x 512) in axial 6-mm slices. The T1-weighted GRE protocol included a pre-saturation pulse over the mediastinal structures. Artefacts and resolution of vessel/airway structures in each lung segment were evaluated by two observers (10 volunteers, 180 segments). Cardiac and vessel pulsation artefacts predominated on T1-weighted GRE, respiration artefacts on T2-weighted TSE (lingula and middle lobe). Pre-saturation of the mediastinum reduced pulsation artefacts on T1-weighted GRE. T1-weighted GRE images were improved by bright flow signal of vessels, whereas image quality of T2-weighted TSE was reduced by black-blood effects in central parts of the lung. Delineation of lung periphery and the mediastinum was superior with T2-weighted TSE. Segmental/sub-segmental vessels (up to fourth/fifth order) and bronchi (up to third order) were identified. All 180 lung segments were imaged in diagnostic quality with at least one of the two sequences (T1-weighted GRE not diagnostic in 9 of 180, T2-weighted TSE in 4 of 180). Both sequences were found to be complementary: superior identification of gross lung anatomy with T1-weighted GRE and higher detail resolution in the periphery and the mediastinum with T2-weighted TSE. (orig.)

Development of Focused Ion Beam technique for high speed steel 3D-SEM artefact fabrication

DEFF Research Database (Denmark)

Carli, Lorenzo; MacDonald, A. Nicole; De Chiffre, Leonardo

2009-01-01

The work describes preliminary manufacture by grinding, followed by machining on a Focused Ion Beam (FIB), of a high speed steel step artefact for 3D-SEM calibration. The FIB is coupled with a SEM in the so called dual beam instrument. The milling capabilities of FIB were checked from a qualitative...... point of view, using the dual beam SEM imaging, and quantitatively using a reference stylus instrument, to establish traceability. A triangular section having a depth of about 10 μm was machined, where the 50 μm curvature radius due to grinding was reduced to about 2 μm by FIB milling...

The effect of metal artefact reduction on CT-based attenuation correction for PET imaging in the vicinity of metallic hip implants : a phantom study

NARCIS (Netherlands)

Harnish, Roy; Prevrhal, Sven; Alavi, Abass; Zaidi, Habib; Lang, Thomas F.

To determine if metal artefact reduction (MAR) combined with a priori knowledge of prosthesis material composition can be applied to obtain CT-based attenuation maps with sufficient accuracy for quantitative assessment of F-18-fluorodeoxyglucose uptake in lesions near metallic prostheses. A custom

Comparative assessment of knee joint models used in multi-body kinematics optimisation for soft tissue artefact compensation.

Science.gov (United States)

Richard, Vincent; Cappozzo, Aurelio; Dumas, Raphaël

2017-09-06

Estimating joint kinematics from skin-marker trajectories recorded using stereophotogrammetry is complicated by soft tissue artefact (STA), an inexorable source of error. One solution is to use a bone pose estimator based on multi-body kinematics optimisation (MKO) embedding joint constraints to compensate for STA. However, there is some debate over the effectiveness of this method. The present study aimed to quantitatively assess the degree of agreement between reference (i.e., artefact-free) knee joint kinematics and the same kinematics estimated using MKO embedding six different knee joint models. The following motor tasks were assessed: level walking, hopping, cutting, running, sit-to-stand, and step-up. Reference knee kinematics was taken from pin-marker or biplane fluoroscopic data acquired concurrently with skin-marker data, made available by the respective authors. For each motor task, Bland-Altman analysis revealed that the performance of MKO varied according to the joint model used, with a wide discrepancy in results across degrees of freedom (DoFs), models and motor tasks (with a bias between -10.2° and 13.2° and between -10.2mm and 7.2mm, and with a confidence interval up to ±14.8° and ±11.1mm, for rotation and displacement, respectively). It can be concluded that, while MKO might occasionally improve kinematics estimation, as implemented to date it does not represent a reliable solution to the STA issue. Copyright © 2017 Elsevier Ltd. All rights reserved.

Iron corrosion in an anoxic soil: Comparison between thermodynamic modelling and ferrous archaeological artefacts characterised along with the local in situ geochemical conditions

Energy Technology Data Exchange (ETDEWEB)

Saheb, M.; Neff, D.; Michelin, A.; Dillmann, P. [CEA Saclay, CNRS, LAPA SIS2M, UMR3299, 91 - Gif-sur-Yvette (France); Saheb, M. [ANDRA, F-92298 Chatenay Malabry (France); Descostes, M. [CEA Saclay, DEN DANS DPC SECR, Lab Radionuclides Migrat Measurements and Modelling, 91 - Gif-sur-Yvette (France); Descostes, M. [Univ Evry, CEA, CNRS, UMR 8587, Evry (France); Dillmann, P. [CNRS, Inst Rech Archeomat, UMR 5060, F-75700 Paris (France)

2010-07-01

This article is part of an ongoing study on the long-term corrosion behaviour of ferrous archaeological artefacts. The aim of this study is to correlate the corrosion products formed on ancient artefacts in an anoxic medium to the environmental data using thermodynamic modelling. For this purpose, measurement campaigns have been conducted on the archaeological site of Glinet (16. century, High Normandy (Seine-Maritime), France) where the evolution of the pore water chemistry has been recorded for a period of one year. Three evolution steps have been distinguished after the oxidizing perturbation which was induced by the piezometers installation. The first step was related to an oxidizing environment in which pore water was in equilibrium with a Fe(III) precipitated phase: ferri-hydrite (FeOOH center dot 0.4 H{sub 2}O). The second step was considered as an intermediate step and Fe speciation had evolved; equilibrium was achieved between ferri-hydrite and a Fe(II) carbonate phase: siderite (Fe(II)CO{sub 3}). The last step of the evolution was related to a reducing stage where pore water was in equilibrium with magnetite (Fe(II, III){sub 3}O{sub 4}) and with chukanovite (Fe(II){sub 2}(OH){sub 2}CO{sub 3}). As these phases were present in the corrosion layers formed on the archaeological samples, it is possible to conclude that the thermodynamic approach was helpful in developing a better understanding of the effect of geochemical conditions on the composition and mineralogy of the corrosion products formed on archaeological artefacts. This work could be used as a reference for further corrosion studies, especially on long-term corrosion processes applied to nuclear waste disposal. (authors)

The Fundamentals Regarding the Usage of the Concept of Interface for the Modeling of the Software Artefacts

Directory of Open Access Journals (Sweden)

Dorin Bocu

2016-03-01

Full Text Available This paper presents the conceptual foundations of a software system’s solution modelling activity, which is formally based on two essential concepts: the artefact and the interface. This  modelling activity envisions  two  objectives: the  explicit emphasis on the  interfaces’ importance in the software engineering, and the preparation of the  framework inside which  the  loop structure-behaviour can be formalized considering the inherent benefits for the  modelling activity in  general, and  for  the  modelling activity automation in particular.

Endogeneously arising network allocation rules

NARCIS (Netherlands)

Slikker, M.

2006-01-01

In this paper we study endogenously arising network allocation rules. We focus on three allocation rules: the Myerson value, the position value and the component-wise egalitarian solution. For any of these three rules we provide a characterization based on component efficiency and some balanced

Optimization of porous microchannel heat exchanger

Science.gov (United States)

Kozhukhov, N. N.; Konovalov, D. A.

2017-11-01

The technical progress in information and communication sphere leads to a sharp increase in the use of radio electronic devices. Functioning of radio electronics is accompanied by release of thermal energy, which must be diverted from the heat-stressed element. Moreover, using of electronics at negative temperatures, on the contrary, requires supply of a certain amount of heat to start the system. There arises the task of creating a system that allows both to supply and to divert the necessary amount of thermal energy. The development of complex thermostabilization systems for radio electronic equipment is due to increasing the efficiency of each of its elements separately. For more efficient operation of a heat exchanger, which directly affects the temperature of the heat-stressed element, it is necessary to calculate the mode characteristics and to take into account the effect of its design parameters. The results of optimizing the microchannel heat exchanger are presented in the article. The target optimization functions are the mass, pressure drop and temperature. The parameters of optimization are the layout of porous fins, their geometric dimensions and coolant flow. For the given conditions, the optimum variant of porous microchannel heat exchanger is selected.

Carcinoma arising in thyroglossal remnants

NARCIS (Netherlands)

van Vuuren, P. A.; Balm, A. J.; Gregor, R. T.; Hilgers, F. J.; Loftus, B. M.; Delprat, C. C.; Rutgers, E. J.

1994-01-01

Three patients with a papillary carcinoma arising in a thyroglossal duct cyst are presented and the literature is reviewed. This rare malignancy is seen mostly in women between the ages of 20 and 50 years. The distribution of carcinoma subtypes differs from that of thyroid carcinomas and

Heat stress and strain in exercise and sport.

Science.gov (United States)

Brotherhood, John R

2008-01-01

Heat stress arising from the thermal environment is of concern to sports medicine and to sports administration because of the perceived risk of heat casualties, in particular heat stroke. Many sports organizations recommend environmental indices such as the WBGT for assessing risk and setting environmental limits for training and competition. But the limits are not justified by evidence. This article describes the nature of heat stress in sport and how it may be assessed objectively. Heat stress and the principal human responses to exercise heat stress are reviewed briefly. Metabolic heat production and the thermal environment provoke separate and largely independent physiological strains. Metabolic heat production drives body core temperature, and the thermal environment drives skin temperature; the combined stresses are integrated to drive sweat rate. Control of core temperature depends on adequate sweat production and the capacity of the environment to evaporate the sweat. The nature of exercise heat stress is demonstrated by rational analysis of the physical heat exchanges between the body and the environment. The principles of this analysis are applied to critical review of current practice in the assessment of heat stress in sport. The article concludes with discussion of research to establish methods for objective sport-specific assessment of heat stress.

Adenosarcoma arising in hepatic endometriosis

International Nuclear Information System (INIS)

N'Senda, P.; Dahan, H.; Tubiana, J.M.; Arrive, L.; Wendum, D.; Balladur, P.

2000-01-01

We report a case of adenosarcoma arising in hepatic endometriosis. Both CT and MR scans demontrated a huge heterogeneous mass containing septated, thick-walled cystic lesions. After enlarged right hepatectomy, the patient was asymptomatic with no abnormalities at liver and abdominal CT scan at 2-year follow-up. (orig.)

Adenosarcoma arising in hepatic endometriosis

Energy Technology Data Exchange (ETDEWEB)

N' Senda, P.; Dahan, H.; Tubiana, J.M.; Arrive, L. [Service de Radiologie, Hopital Saint-Antoine, 75 - Paris (France); Wendum, D. [Service d' Anatomie Pathologie, Hopital Saint-Antoine, 75 - Paris (France); Balladur, P. [Service de Chirurgie Digestive et Generale, Hopital Saint-Antoine, 75 - Paris (France)

2000-08-01

We report a case of adenosarcoma arising in hepatic endometriosis. Both CT and MR scans demontrated a huge heterogeneous mass containing septated, thick-walled cystic lesions. After enlarged right hepatectomy, the patient was asymptomatic with no abnormalities at liver and abdominal CT scan at 2-year follow-up. (orig.)

Cutaneous osteosarcoma arising from a burn scar

Energy Technology Data Exchange (ETDEWEB)

Lee, Min A.; Yi, Jaehyuck [Kyungpook National University, Department of Radiology, College of Medicine, Daegu (Korea, Republic of); Kyungpook National University Hospital, Department of Radiology, Daegu (Korea, Republic of); Chae, Jong Min [Kyungpook National University, Department of Pathology, College of Medicine, Daegu (Korea, Republic of)

2017-04-15

Tumors that develop in old burn scars are usually squamous cell carcinomas. Sarcomas have also been reported, albeit rarely. To our knowledge, there has been only one case report of an extraskeletal osteosarcoma arising in a prior burn scar reported in the English-language literature, mainly discussing the clinicopathological features. Herein, we present a case of cutaneous osteosarcoma visualized as a mineralized soft-tissue mass arising from the scar associated with a previous skin burn over the back. This seems to be the first report describing the imaging features of a cutaneous osteosarcoma from an old burn scar. (orig.)

Synchronizing the transcranial magnetic pulse with electroencephalographic recordings effectively reduces inter-trial variability of the pulse artefact

DEFF Research Database (Denmark)

Tomasevic, Leo; Takemi, Mitsuaki; Siebner, Hartwig Roman

2017-01-01

delivered monophasic and biphasic TMS to a melon as head phantom and to four healthy participants and recorded the pulse artefact at 5 kHz with a TMS-compatible EEG system. Pulse delivery was either synchronized or non-synchronized to the clock of the EEG recording system. The effects of synchronization...... were tested at 10 and 20 kHz using the head phantom. We also tested the effect of a soft sheet placed between the stimulation coil and recording electrodes in both human and melon. RESULTS & CONCLUSION: Synchronizing TMS and data acquisition markedly reduced trial-to-trial variability of the pulse...

Direct currents produced by hf heating of plasma

International Nuclear Information System (INIS)

Klima, R.

1974-01-01

In addition to the well-known diffusion currents, toroidal direct currents arise in h.f. heated plasmas as a result of a momentum transfer from the h.f. field to plasma particles. The estimates of steady-state conditions are given for these currents. Particularly, the possibility of stationary operation of a Tokamak device is analyzed. (author)

Calibrating the X-ray attenuation of liquid water and correcting sample movement artefacts during in operando synchrotron X-ray radiographic imaging of polymer electrolyte membrane fuel cells.

Science.gov (United States)

Ge, Nan; Chevalier, Stéphane; Hinebaugh, James; Yip, Ronnie; Lee, Jongmin; Antonacci, Patrick; Kotaka, Toshikazu; Tabuchi, Yuichiro; Bazylak, Aimy

2016-03-01

Synchrotron X-ray radiography, due to its high temporal and spatial resolutions, provides a valuable means for understanding the in operando water transport behaviour in polymer electrolyte membrane fuel cells. The purpose of this study is to address the specific artefact of imaging sample movement, which poses a significant challenge to synchrotron-based imaging for fuel cell diagnostics. Specifically, the impact of the micrometer-scale movement of the sample was determined, and a correction methodology was developed. At a photon energy level of 20 keV, a maximum movement of 7.5 µm resulted in a false water thickness of 0.93 cm (9% higher than the maximum amount of water that the experimental apparatus could physically contain). This artefact was corrected by image translations based on the relationship between the false water thickness value and the distance moved by the sample. The implementation of this correction method led to a significant reduction in false water thickness (to ∼0.04 cm). Furthermore, to account for inaccuracies in pixel intensities due to the scattering effect and higher harmonics, a calibration technique was introduced for the liquid water X-ray attenuation coefficient, which was found to be 0.657 ± 0.023 cm(-1) at 20 keV. The work presented in this paper provides valuable tools for artefact compensation and accuracy improvements for dynamic synchrotron X-ray imaging of fuel cells.

HEATING-7, Multidimensional Finite-Difference Heat Conduction Analysis

International Nuclear Information System (INIS)

2000-01-01

problems, surface fluxes may be plotted with H7TECPLOT which requires the proprietary software TECPLOT. HEATING 7.3 runs under Windows95 and WindowsNT on PC's. No future modifications are planned for HEATING7. See README.1ST for more information. 2 - Method of solution: Three steady-state solution techniques are available: point-successive over-relaxation iterative method with extrapolation, direct-solution (for one-dimensional or two-dimensional problems), and conjugate gradient. Transient problems may be solved using any one of several finite-difference schemes: Crank-Nicolson implicit, Classical Implicit Procedure (CIP), Classical Explicit Procedure (CEP), or Levy explicit method (which for some circumstances allows a time step greater than the CEP stability criterion.) The solution of the system of equations arising from the implicit techniques is accomplished by point-successive over-relaxation iteration and includes procedures to estimate the optimum acceleration parameter. 3 - Restrictions on the complexity of the problem: All surfaces in a model must be parallel to one of the coordinate axes which makes modeling complex geometries difficult. Transient change of phase problems can only be solved with one of the explicit techniques - an implicit change-of-phase capability has not been implemented

Underground disposal of UK heat-generating wastes: repository design considerations

International Nuclear Information System (INIS)

Steadman, J.A.

1993-12-01

The report discusses the likely differences in design between a deep repository for disposal of UK heat-generating radioactive wastes and that of the planned Nirex ILW/LLW repository at Sellafield, based on a review of international published information. The main differences arise from the greater heat and radiation outputs of the waste, and in the case of intact PWR spent fuel elements, the greater length and weight of the disposal packages. Published cost estimates for other OECD countries for disposal of heat-generating wastes are considerably lower than that for the UK, partly because in most cases they are for co-disposal with a larger quantity of ILW. (author)

32 CFR 537.19 - Demands arising from maritime claims.

Science.gov (United States)

2010-07-01

... 32 National Defense 3 2010-07-01 2010-07-01 true Demands arising from maritime claims. 537.19 Section 537.19 National Defense Department of Defense (Continued) DEPARTMENT OF THE ARMY CLAIMS AND ACCOUNTS CLAIMS ON BEHALF OF THE UNITED STATES § 537.19 Demands arising from maritime claims. (a) It is...

Quantitative analysis of orthopedic metal artefact reduction in 64-slice computed tomography scans in large head metal-on-metal total hip replacement, a phantom study

NARCIS (Netherlands)

Boomsma, Martijn F.; Warringa, Niek; Edens, Mireille A.; Mueller, Dirk; Ettema, Harmen B.; Verheyen, Cees C. P. M.; Maas, Mario

2016-01-01

Purpose: Quantification of the effect of O-MAR on decreasing metal artefacts caused by large head metal on metal total hip arthroplasty (MoM THA) in a dedicated phantom setup of the hip. Background: Pathological reactions of the hip capsule on Computed tomography (CT) can be difficult to diagnose

Multi-slice ultrasound image calibration of an intelligent skin-marker for soft tissue artefact compensation.

Science.gov (United States)

Masum, M A; Pickering, M R; Lambert, A J; Scarvell, J M; Smith, P N

2017-09-06

In this paper, a novel multi-slice ultrasound (US) image calibration of an intelligent skin-marker used for soft tissue artefact compensation is proposed to align and orient image slices in an exact H-shaped pattern. Multi-slice calibration is complex, however, in the proposed method, a phantom based visual alignment followed by transform parameters estimation greatly reduces the complexity and provides sufficient accuracy. In this approach, the Hough Transform (HT) is used to further enhance the image features which originate from the image feature enhancing elements integrated into the physical phantom model, thus reducing feature detection uncertainty. In this framework, slice by slice image alignment and calibration are carried out and this provides manual ease and convenience. Copyright © 2016 Elsevier Ltd. All rights reserved.

Goldtraces on wedge-shaped artefacts from late neolithic of south Scandinavia analysed by proton induced x-ray emission spectroscopy

International Nuclear Information System (INIS)

Ahlberg, M.; Akselsson, R.; Forkman, B.; Rausing, G.

1975-01-01

Visible coloured traces on the surface of two selected wedge-shaped artefacts (pendants) of slate from the late Neolithic of South Scandinavia was analysed by means of proton-induced x-ray emission spectroscopy (PIXE). PIXE is shown to be a feasible tool in investigating surface layers of archeological significance. Three different gold-silver alloys was found on the two pendants. The results indicate that we shall have to reconsider the general accepted theories on the economic basis of the early Bronze Age in the area. (author)

A mathematical model of heat flow in a thermopile for measuring muscle heat production: implications for design and signal analysis.

Science.gov (United States)

Barclay, C J

2015-09-01

Contracting muscles produce heat which largely arises from the biochemical reactions that provide the energy for contraction. Measurements of muscle heat production have made, and continue to make, important contributions to our understanding of the bases of contraction. Most measurements of muscle heat production are made using a thermopile, consisting of a series of thermocouples arranged so that alternate thermocouples are in thermal contact with the muscle and with an isothermal reference. In this study, a mathematical model was constructed of a muscle lying on a thermopile consisting of antimony-bismuth thermocouples sandwiched between polymer sheets. The validity of the model was demonstrated by its ability to accurately predict thermopile outputs in response to applying heat to the thermopile surface, to generating heat in the thermocouples using the Peltier effect and to adding heat capacity on the thermopile surface. The model was then used to show how practical changes to thermopile construction could minimise response time and thermopile heat capacity and allow measurement of very low rates of heat production. The impulse response of a muscle-thermopile system was generated using the model and used to illustrate how a measured signal can be deconvolved with the impulse response to correct for lag introduced by the thermopile.

Metal artefacts severely hamper magnetic resonance imaging of the rotator cuff tendons after rotator cuff repair with titanium suture anchors.

Science.gov (United States)

Schröder, Femke F; Huis In't Veld, Rianne; den Otter, Lydia A; van Raak, Sjoerd M; Ten Haken, Bennie; Vochteloo, Anne J H

2018-04-01

The rate of retear after rotator cuff surgery is 17%. Magnetic resonance imaging (MRI) scans are used for confirmative diagnosis of retear. However, because of the presence of titanium suture anchors, metal artefacts on the MRI are common. The present study evaluated the diagnostic value of MRI after rotator cuff tendon surgery with respect to assessing the integrity as well as the degeneration and atrophy of the rotator cuff tendons when titanium anchors are in place. Twenty patients who underwent revision surgery of the rotator cuff as a result of a clinically suspected retear between 2013 and 2015 were included. The MRI scans of these patients were retrospectively analyzed by four specialized shoulder surgeons and compared with intra-operative findings (gold standard). Sensitivity and interobserver agreement among the surgeons in assessing retears as well as the Goutallier and Warner classification were examined. In 36% (range 15% to 50%) of the pre-operative MRI scans, the observers could not review the rotator cuff tendons. When the rotator cuff tendons were assessable, a diagnostic accuracy with a mean sensitivity of 0.84 (0.70 to 1.0) across the surgeons was found, with poor interobserver agreement (kappa = 0.12). Metal artefacts prevented accurate diagnosis from MRI scans of rotator cuff retear in 36% of the patients studied.

Cell respiration under hypoxia: facts and artefacts in mitochondrial oxygen kinetics.

Science.gov (United States)

Scandurra, Francesca M; Gnaiger, Erich

2010-01-01

When oxygen supply to tissues is limiting, mitochondrial respiration and ATP production are compromised. To assess the bioenergetic consequences under normoxia and hypoxia, quantitative evaluation of mitochondrial oxygen kinetics is required. Using high-resolution respirometry, the "apparent K (m)" for oxygen or p (50) of respiration in 32D cells was determined at 0.05 +/- 0.01 kPa (0.4 mmHg, 0.5 microM, 0.25% air saturation). Close agreement with p (50) of isolated mitochondria indicates that intracellular gradients are small in small cells at routine activity. At intracellular p (O2) respiration is limited by >2% with a p (50) of 0.05 kPa. Over-estimation of p (50) at 0.4 kPa (3 mmHg) would imply significant (>17%) oxygen limitation of respiration under intracellular normoxia. Based on a critical review, we conclude that p (50) ranges from 0.01 to 0.10 kPa in mitochondria and small cells in the absence of inhibitors of cytochrome c oxidase, whereas experimental artefacts explain the controversial >200-fold range of p (50) in the literature on mitochondrial oxygen kinetics.

Supporting BPMN choreography with system integration artefacts for enterprise process collaboration

Science.gov (United States)

Nie, Hongchao; Lu, Xudong; Duan, Huilong

2014-07-01

Business Process Model and Notation (BPMN) choreography modelling depicts externally visible message exchanges between collaborating processes of enterprise information systems. Implementation of choreography relies on designing system integration solutions to realise message exchanges between independently developed systems. Enterprise integration patterns (EIPs) are widely accepted artefacts to design integration solutions. If the choreography model represents coordination requirements between processes with behaviour mismatches, the integration designer needs to analyse the routing requirements and address these requirements by manually designing EIP message routers. As collaboration scales and complexity increases, manual design becomes inefficient. Thus, the research problem of this paper is to explore a method to automatically identify routing requirements from BPMN choreography model and to accordingly design routing in the integration solution. To achieve this goal, recurring behaviour mismatch scenarios are analysed as patterns, and corresponding solutions are proposed as EIP routers. Using this method, a choreography model can be analysed by computer to identify occurrences of mismatch patterns, leading to corresponding router selection. A case study demonstrates that the proposed method enables computer-assisted integration design to implement choreography. A further experiment reveals that the method is effective to improve the design quality and reduce time cost.

Four Different Tumors Arising in a Nevus Sebaceous

Directory of Open Access Journals (Sweden)

Takeshi Namiki

2016-04-01

Full Text Available Nevus sebaceous is known by its association with one or more secondary tumors, but more than three multiple tumors arising from a nevus sebaceous is extremely rare. A 67-year-old female presented with a light brown plaque on the back of her head that contained a dome-shaped black node and an erosive lesion. Histopathological examination showed atypical basaloid cells in the black node. At the periphery of that node, structures resembling follicular germs extruded from interlacing cords in the upper portion and tumor nests with sebocytes were in the lower portion. In the erosive lesion, papillated structures with an apocrine epithelium were observed. In the light brown plaque, enlargement of sebaceous lobules was noted. From those histopathological features, a diagnosis of syringocystadenoma papilliferum, sebaceoma, trichoblastoma and basal cell carcinoma arising from a nevus sebaceous was made. We discuss the rarity of multiple tumors arising from a nevus sebaceous.

The effect of load factor on fission product decay heat from discharged reactor fuel

International Nuclear Information System (INIS)

Davies, B.S.J.

1978-07-01

A sum-of-exponentials expression representing the decay heat power following a burst thermal irradiation of 235 U has been used to investigate the effect of load factor during irradiation on subsequent decay heat production. A sequence of random numbers was used to indicate reactor 'on' and 'off' periods for irradiations which continued for a total of 1500 days at power and were followed by 100 days cooling. It was found that for these conditions decay heat is almost proportional to load factor. Estimates of decay heat uncertainty arising from the random irradiation pattern are also given. (author)

Resistive Heating in Saturn's Thermosphere

Science.gov (United States)

Vriesema, Jess W.; Koskinen, Tommi; Yelle, Roger V.

2016-10-01

The thermospheres of the jovian planets are several times hotter than solar heating alone can account for. On Saturn, resistive heating appears sufficient to explain these temperatures in auroral regions, but the particular mechanism(s) responsible for heating the lower latitudes remains unclear. Smith et al. (2005) suggested that electrodynamics of the equatorial region—particularly resistive heating caused by strong electrojet currents—might explain the observed temperatures at low latitudes. Müller-Wodarg et al. (2006) found that their circulation model could reproduce low-latitude temperatures only when they included resistive heating at the poles and applied a uniform, generic heating source globally. Smith et al. (2007) concluded that heating at the poles leads to meridional circulation that cools low latitudes and argued that in-situ heating is required to explain the temperatures at low latitudes.Resistive heating at low latitudes, arising from enhanced current generation driven by thermospheric winds, is a potentially important in-situ heating mechanism. Ion drag caused by low-latitude electrodynamics can modify global circulation and meridional transport of energy. We present an axisymmetric, steady-state formulation of wind-driven electrodynamics to investigate these possibilities throughout Saturn's thermosphere. At present, we assume a dipole magnetic field and neglect any contributions from the magnetosphere. We use ion mixing ratios from the model of Kim et al. (2014) and the observed temperature-pressure profile from Koskinen et al. (2015) to calculate the generalized conductivity tensor as described by Koskinen et al. (2014). Our model solves the coupled equations for charge continuity and Ohm's law with tensor conductivity while enforcing zero current across the boundaries. The resulting partial differential equation is solved for the current density throughout the domain and used to calculate the net resistive heating rate. We demonstrate

Conjunctival lymphoma arising from reactive lymphoid hyperplasia

Directory of Open Access Journals (Sweden)

Fukuhara Junichi

2012-09-01

Full Text Available Abstract Extra nodal marginal zone B-cell lymphoma (EMZL of the conjunctiva typically arises in the marginal zone of mucosa-associated lymphoid tissue. The pathogenesis of conjunctival EMZL remains unknown. We describe an unusual case of EMZL arising from reactive lymphoid hyperplasia (RLH of the conjunctiva. A 35-year-old woman had fleshy salmon-pink conjunctival tumors in both eyes, oculus uterque (OU. Specimens from conjunctival tumors in the right eye, oculus dexter (OD, revealed a collection of small lymphoid cells in the stroma. Immunohistochemically, immunoglobulin (Ig light chain restriction was not detected. In contrast, diffuse atypical lymphoid cell infiltration was noted in the left eye, oculus sinister (OS, and positive for CD20, a marker for B cells OS. The tumors were histologically diagnosed as RLH OD, and EMZL OS. PCR analysis detected IgH gene rearrangement in the joining region (JH region OU. After 11 months, a re-biopsy specimen demonstrated EMZL based on compatible pathological and genetic findings OD, arising from RLH. This case suggests that even if the diagnosis of the conjunctival lymphoproliferative lesions is histologically benign, confirmation of the B-cell clonality by checking IgH gene rearrangement should be useful to predict the incidence of malignancy.

32 CFR 536.111 - Investigation of claims arising under international agreements (for those claims arising in the...

Science.gov (United States)

2010-07-01

... under international agreements (for those claims arising in the United States). Responsibility for... civilian component is attached, including the legal office of another armed force, to carry out the responsibility to investigate. The investigation will comply with the responsible Service's implementing claims...

Squamous cell carcinoma arising in mature cystic teratoma of ovary

Directory of Open Access Journals (Sweden)

Ranu Patni

2014-01-01

Full Text Available Squamous cell carcinoma of the ovary is a rare condition and usually arises in mature cystic teratoma (MCT or dermoid cyst of the ovary. The reported incidence of malignant transformation in MCT is approximately 2%. A case of squamous cell carcinoma arising in a dermoid cyst of the ovary presenting at an early stage is presented here. A 53-year-old postmenopausal lady, presented with the complaint of pain in right lower abdomen since one month and a large complex abdomino-pelvic mass on examination and investigations. Final histopathology was reported as squamous cell carcinoma of left ovary arising from dermoid cyst and a benign dermoid cyst in the right ovary. The patient was assigned to squamous cell carcinoma of the ovary arising in a mature cystic teratoma, surgical stage Ic2. In view of the poor prognosis, adjuvant chemotherapy was started.

Shutdown risk analysis for a BWR plant (residual heat removal systems)

International Nuclear Information System (INIS)

Rebollo Garcia, C.; Merino Teillet, A.; Cerezo, L.

1994-01-01

This report analyses the different risk situations which may arise during refuelling outage at Cofrentes NPP. The most critical situations are determined in terms of the small amount of coolant available and the lowest number of heat removal and water make-up systems available. The available times before the boiling point of the coolant is reached and the subsequent moment when the fuel elements are left uncovered in the event of the failure of the normal heat removal functions are determined. The analysis identifies the alternative systems which can be used besides those required by the technical specification and their capacity for residual heat removal and coolant make-up functions. (Author)

Direction of Impurity Pinch and Auxiliary Heating in Tokamak Plasmas

International Nuclear Information System (INIS)

Angioni, C.; Peeters, A.G.

2006-01-01

A mechanism of particle pinch for trace impurities in tokamak plasmas, arising from the effect of parallel velocity fluctuations in the presence of a turbulent electrostatic potential, is identified analytically by means of a reduced fluid model and verified numerically with a gyrokinetic code for the first time. The direction of such a pinch reverses as a function of the direction of rotation of the turbulence in agreement with the impurity pinch reversal observed in some experiments when moving from dominant auxiliary ion heating to dominant auxiliary electron heating

Spectral artefacts post sputter-etching and how to cope with them - A case study of XPS on nitride-based coatings using monoatomic and cluster ion beams

Science.gov (United States)

Lewin, Erik; Counsell, Jonathan; Patscheider, Jörg

2018-06-01

The issue of artefacts due to sputter-etching has been investigated for a group of AlN-based thin film materials with varying thermodynamical stability. Stability of the materials was controlled by alloying AlN with the group 14 elements Si, Ge or Sn in two different concentrations. The coatings were sputter-etched with monoatomic Ar+ with energies between 0.2 and 4.0 keV to study the sensitivity of the materials for sputter damage. The use of Arn+ clusters to remove an oxidised surface layer was also evaluated for a selected sample. The spectra were compared to pristine spectra obtained after in-vacuo sample transfer from the synthesis chamber to the analysis instrument. It was found that the all samples were affected by high energy (4 keV) Ar+ ions to varying degrees. The determining factors for the amount of observed damage were found to be the materials' enthalpy of formation, where a threshold value seems to exist at approximately -1.25 eV/atom (∼-120 kJ/mol atoms). For each sample, the observed amount of damage was found to have a linear dependence to the energy deposited by the ion beam per volume removed material. Despite the occurrence of sputter-damage in all samples, etching settings that result in almost artefact-free spectral data were found; using either very low energy (i.e. 200 eV) monoatomic ions, or an appropriate combination of ion cluster size and energy. The present study underlines that analysis post sputter-etching must be carried out with an awareness of possible sputter-induced artefacts.

ARISE: American renaissance in science education

Energy Technology Data Exchange (ETDEWEB)

NONE

1998-09-14

The national standards and state derivatives must be reinforced by models of curricular reform. In this paper, ARISE presents one model based on a set of principles--coherence, integration of the sciences, movement from concrete ideas to abstract ones, inquiry, connection and application, sequencing that is responsive to how people learn.

The impact of Digitalization on Business Models: How IT Artefacts, Social Media, and Big Data Force Firms to Innovate Their Business Model

OpenAIRE

Bouwman, Harry; de Reuver, Mark; Nikou, Shahrokh

2017-01-01

Digital technology has forced entrepreneurs to reconsider their business models (BMs). Although research on entrepreneurial intention and business models is gaining attention, there is still a large knowledge gap on both fields. In this paper, we specifically address the impact of digitalization on business model innovation (BMI). Based on data collected from 338 European small- to medium-sized enterprises (SMEs) actively using IT artefacts, social media, or big data to innovate their busines...

Issues arising in applying the BSS concepts

International Nuclear Information System (INIS)

Linsley, G.

1997-01-01

The following issues are discussed arising in applying the basic safety standard concepts: terminology, naturally occurring radionuclides, the exemption and clearance levels, management of very low level wastes, transboundary movements, the waste convention

Dynamic Complexity Study of Nuclear Reactor and Process Heat Application Integration

International Nuclear Information System (INIS)

Taylor, J'Tia Patrice; Shropshire, David E.

2009-01-01

This paper describes the key obstacles and challenges facing the integration of nuclear reactors with process heat applications as they relate to dynamic issues. The paper also presents capabilities of current modeling and analysis tools available to investigate these issues. A pragmatic approach to an analysis is developed with the ultimate objective of improving the viability of nuclear energy as a heat source for process industries. The extension of nuclear energy to process heat industries would improve energy security and aid in reduction of carbon emissions by reducing demands for foreign derived fossil fuels. The paper begins with an overview of nuclear reactors and process application for potential use in an integrated system. Reactors are evaluated against specific characteristics that determine their compatibility with process applications such as heat outlet temperature. The reactor system categories include light water, heavy water, small to medium, near term high-temperature, and far term high temperature reactors. Low temperature process systems include desalination, district heating, and tar sands and shale oil recovery. High temperature processes that support hydrogen production include steam reforming, steam cracking, hydrogen production by electrolysis, and far-term applications such as the sulfur iodine chemical process and high-temperature electrolysis. A simple static matching between complementary systems is performed; however, to gain a true appreciation for system integration complexity, time dependent dynamic analysis is required. The paper identifies critical issues arising from dynamic complexity associated with integration of systems. Operational issues include scheduling conflicts and resource allocation for heat and electricity. Additionally, economic and safety considerations that could impact the successful integration of these systems are considered. Economic issues include the cost differential arising due to an integrated system

Critical heat fluxes in tubular fuel elements of nuclear power reactors

International Nuclear Information System (INIS)

Subbotin, V.I.; Alekseev, G.V.; Peskov, O.L.

1974-01-01

The results of the experiments carried out show that with appropriate choice of tube, type and dimensions of intensifier the attainment of critical conditions at certain parameters is not accompanied by sharp or considerable increases in temperature of the heat removing surface. Increase in power to above critical under these conditions does not lead to considerable variation in temperature either. Thus, it appears possible to change from heat removal by steam-water mixture to convective heat removal by wet steam without manifestation of intolerable temperature conditions of the heating surface (Fig. 6). A change to convective heat removal by wet steam is possible at different levels of heat fluxes which depend during constant conditions at the inlet on tube length and the degree of the disturbing influence on the flow. This is especially important since in principle the possibility arises for developing a power reactor with tubular fuel elements, in which a once-through cycle with steam superheat involving no intermediate separation can be realised

Mechanisms of convective and boiling heat transfer enhancement via ultrasonic vibration

International Nuclear Information System (INIS)

Kim, Yi Gu; Kim, Ho Young; Kang, Seoung Min; Kang, Byung Ha; Lee, Jin Ho

2003-01-01

This work experimentally studies the fundamental mechanisms by which the ultrasonic vibration enhances convection and pool boiling heat transfer. A thin platinum wire is used as both a heat source and a temperature sensor. A high speed video imaging system is employed to observe the behavior of cavitation and thermal bubbles. It is found that when the liquid temperature is below its boiling point, cavitation takes place due to ultrasonic vibration while cavitation disappears when the liquid reaches the boiling point. Moreover, when the gas dissolved in liquid is removed by pre-degassing, the cavitation arises only locally. Depending on the liquid temperature, heat transfer rates in convection, subcooled boiling and saturated boiling regimes are examined. In convection heat transfer regime, fully agitated cavitation is the most efficient heat transfer enhancement mechanism. Subcooled boiling is most enhanced when the local cavitation is induced after degassing. In saturated boiling regime, acoustic pressure is shown to be a dominant heat transfer enhancement mechanism

Influence of the boundary conditions on heat and mass transfer in spacer-filled channels

Science.gov (United States)

Ciofalo, M.; La Cerva, M. F.; Di Liberto, M.; Tamburini, A.

2017-11-01

The purpose of this study is to discuss some problems which arise in heat or mass transfer in complex channels, with special reference to the spacer-filled channels adopted in membrane processes. Among the issues addressed are the consistent definition of local and mean heat or mass transfer coefficients; the influence of the wall boundary conditions; the influence of one-side versus two-side heat/mass transfer. Most of the results discussed were obtained by finite volume CFD simulations concerning heat transfer in Membrane Distillation or mass transfer in Electrodialysis and Reverse Electrodialysis, but many of the conclusions apply also to different processes involving geometrically complex channels

Use of neutron diffraction and laser-induced plasma spectroscopy in integrated authentication methodologies of copper alloy artefacts

International Nuclear Information System (INIS)

Siano, S.; Bartol, L.; Mencaglia, A.A.; Agresti, J.; Miccio, M.

2009-01-01

The present study approaches the general problem of the authentication of copper alloy artefacts of art and historical interest using non-invasive analytical techniques. It aims to demonstrate that a suitable combination of time-of-flight neutron diffraction and laser-induced plasma spectroscopy in integrated multidisciplinary authentication methodologies can provide crucial data for discriminating between genuine archaeological objects and modern counterfeits. After introducing the methodology, which is dedicated in particular to copper alloy figurines of ancient style, two representative authentication case studies are discussed. The results of the work provide evidence that the combination of multiphase analysis using TOF-N D and elemental depth profiles provided by Lips makes it possible to solve most of the present authentication problems.

A cell shrinkage artefact in growth plate chondrocytes with common fixative solutions: importance of fixative osmolarity for maintaining morphology

Directory of Open Access Journals (Sweden)

MY Loqman

2010-05-01

Full Text Available The remarkable increase in chondrocyte volume is a major determinant in the longitudinal growth of mammalian bones. To permit a detailed morphological study of hypertrophic chondrocytes using standard histological techniques, the preservation of normal chondrocyte morphology is essential. We noticed that during fixation of growth plates with conventional fixative solutions, there was a marked morphological (shrinkage artifact, and we postulated that this arose from the hyper-osmotic nature of these solutions. To test this, we fixed proximal tibia growth plates of 7-day-old rat bones in either (a paraformaldehyde (PFA; 4%, (b glutaraldehyde (GA; 2% with PFA (2% with ruthenium hexamine trichloride (RHT; 0.7%, (c GA (2% with RHT (0.7%, or (d GA (1.3% with RHT (0.5% and osmolarity adjusted to a ‘physiological’ level of ~280mOsm. Using conventional histological methods, confocal microscopy, and image analysis on fluorescently-labelled fixed and living chondrocytes, we then quantified the extent of cell shrinkage and volume change. Our data showed that the high osmolarity of conventional fixatives caused a shrinkage artefact to chondrocytes. This was particularly evident when whole bones were fixed, but could be markedly reduced if bones were sagittally bisected prior to fixation. The shrinkage artefact could be avoided by adjusting the osmolarity of the fixatives to the osmotic pressure of normal extracellular fluids (~280mOsm. These results emphasize the importance of fixative osmolarity, in order to accurately preserve the normal volume/morphology of cells within tissues.

Not all that glitters is gold - Electron microscopy study on uptake of gold nanoparticles in Daphnia magna and related artefacts

DEFF Research Database (Denmark)

Jensen, Louise Helene Søgaard; Skjolding, Lars Michael; Thit, Amalie

2017-01-01

techniques are used to investigate internalization of 10 nm gold nanoparticles in Daphnia magna gut lumen and gut epithelial cells upon 24h exposure and outline potential artefacts, i.e. high contract precipitates from sample preparation related to these techniques. Light sheet microscopy confirmed...... accumulation of gold nanoparticles in the gut lumen. Scanning transmission electron microscopy and elemental analysis revealed gold nanoparticles attached to the microvilli of gut cells. Interestingly, the peritrophic membrane appeared to act as a semipermeable barrier between the lumen and the gut epithelium...

Electric reaction arising in bone subjected to mechanical loadings

Science.gov (United States)

Murasawa, Go; Cho, Hideo; Ogawa, Kazuma

2006-03-01

The aim of present study is the investigation of the electric reaction arising in bone subjected to mechanical loadings. Firstly, specimen was fabricated from femur of cow, and ultrasonic propagation in bone was measured by ultrasonic technique. Secondary, 4-point bending test was conducted up to fracture, and electric reaction arising in bone was measured during loading. Thirdly, cyclic 4-point bending test was conducted to investigate the effect of applied displacement speed on electric reaction.

Ultrasonic evaluation of heat treatment for stress relief in steel

International Nuclear Information System (INIS)

Bittencourt, Marcelo de S.Q.; Lamy, Carlos A.; Goncalves Filho, Orlando J.A.; Payao Filho, Joao da C.

2000-01-01

Residual stresses in materials arise due to the manufacturing processes. As a consequence, in the nuclear area some components must suffer a stress relief treatment according to strict criteria. Although these treatments are carefully carried on, concern with nuclear safety is constantly growing. This work proposes a nondestructive ultrasonic method to guarantee the efficiency of the heat treatment. It was used a short peened steel plate with tensile and compressive stresses which was submitted to a stress relief treatment. The results show that the proposed ultrasonic method could be used to confirm the efficiency of the stress relief heat treatment. (author)

Sensitivity and uncertainty analysis for fission product decay heat calculations

International Nuclear Information System (INIS)

Rebah, J.; Lee, Y.K.; Nimal, J.C.; Nimal, B.; Luneville, L.; Duchemin, B.

1994-01-01

The calculated uncertainty in decay heat due to the uncertainty in basic nuclear data given in the CEA86 Library, is presented. Uncertainties in summation calculation arise from several sources: fission product yields, half-lives and average decay energies. The correlation between basic data is taken into account. The uncertainty analysis were obtained for thermal-neutron-induced fission of U235 and Pu239 in the case of burst fission and irradiation time. The calculated decay heat in this study is compared with experimental results and with new calculation using the JEF2 Library. (from authors) 6 figs., 19 refs

Supercritical heat transfer in an annular channel with two-sided heaing

International Nuclear Information System (INIS)

Sergeev, V.V.; Remizov, O.V.; Gal'chenko, Eh.F.

1986-01-01

The paper deals with experimental inestigation into worsening of heat transfer at forced up flow in steam-water mixture in a vertical annular channel with two-sided heating and development of technique for calculation of supercritical heat exchange in this channel. Bench-scale experiments are carried out at high-pressure at mass rates of the coolant equal to 300-865 kg/(m 2 x s), pressure of 9.8-17.8 MPa and heat flux on the internal surface - 20-400 kW/m 2 , on the external surface - 35-450 kW/m 2 . Technique for calculation of supercritical heat exchange in channels with one- and two-sided heating is suggested. Analysis of the obtained experimental data permits to determine conditions for arising departure nucleate boiling on the internal and external surfaces and on both surfaces simultaneously. It is concluded that the suggested technique of calculation adequately reflects the effect of regime parameters of coolant flow on temperature regime of heat transferring surfaces in the supercritical area

Evaluation of mechanical design fire brick at test section on the HeaTiNG-02

International Nuclear Information System (INIS)

Dedy Haryanto; Riswan Djambiar; Sagino; Edy Sumarno

2013-01-01

The activity was carried out due to the modification of the heating in the HeaTiNG-02 test section. Modification of the heater needs to be done to overcome the obstacles that arise as part of the test section is used. Constraint that often arises is the fall of the heating source with super khantal material when it reaches a certain temperature. To mitigate the super khantal position is initially converted into a vertical position horizontal. The change from vertical to horizontal position on super khantal cause any deformities in refractory fire brick which serves as a support super khantal. Manufacture of refractory design fire brick formation and mechanical strength evaluation performed using CATIA V5 R20 software. Evaluation of fireproof rock mechanics to be based on the mechanical properties of alumina as a refractory material of fire brick. The results of the analysis have a fire brick design stress greater than the bend strength alumina materials, so that the necessary checks before and after the experiment as well as the replacement of refractory fire brick if something is broken. Translational greatest displacement 0.453 mm at a temperature of 1575 K did not give any meaningful form. Thus the refractory fire brick design can be used as heating source support in the HeaTiNG-02 test section with checks before and after the operation. (author)

On artefact-free reconstruction of low-energy (30–250 eV) electron holograms

Energy Technology Data Exchange (ETDEWEB)

Latychevskaia, Tatiana, E-mail: tatiana@physik.uzh.ch; Longchamp, Jean-Nicolas; Escher, Conrad; Fink, Hans-Werner

2014-10-15

Low-energy electrons (30–250 eV) have been successfully employed for imaging individual biomolecules. The most simple and elegant design of a low-energy electron microscope for imaging biomolecules is a lensless setup that operates in the holographic mode. In this work we address the problem associated with the reconstruction from the recorded holograms. We discuss the twin image problem intrinsic to inline holography and the problem of the so-called biprism-like effect specific to low-energy electrons. We demonstrate how the presence of the biprism-like effect can be efficiently identified and circumvented. The presented sideband filtering reconstruction method eliminates the twin image and allows for reconstruction despite the biprism-like effect, which we demonstrate on both, simulated and experimental examples. - Highlights: • Radiation damage-free imaging of individual biomolecules. • Elimination of the twin image in inline holograms. • Circumventing biprism-like effect in low-energy electron holograms. • Artefact-free reconstructions of low-energy electron holograms.

On artefact-free reconstruction of low-energy (30–250 eV) electron holograms

International Nuclear Information System (INIS)

Latychevskaia, Tatiana; Longchamp, Jean-Nicolas; Escher, Conrad; Fink, Hans-Werner

2014-01-01

Low-energy electrons (30–250 eV) have been successfully employed for imaging individual biomolecules. The most simple and elegant design of a low-energy electron microscope for imaging biomolecules is a lensless setup that operates in the holographic mode. In this work we address the problem associated with the reconstruction from the recorded holograms. We discuss the twin image problem intrinsic to inline holography and the problem of the so-called biprism-like effect specific to low-energy electrons. We demonstrate how the presence of the biprism-like effect can be efficiently identified and circumvented. The presented sideband filtering reconstruction method eliminates the twin image and allows for reconstruction despite the biprism-like effect, which we demonstrate on both, simulated and experimental examples. - Highlights: • Radiation damage-free imaging of individual biomolecules. • Elimination of the twin image in inline holograms. • Circumventing biprism-like effect in low-energy electron holograms. • Artefact-free reconstructions of low-energy electron holograms

The characterisation of non-evaporable getters by Auger electron spectroscopy Analytical potential and artefacts

CERN Document Server

Scheuerlein, C; Taborelli, M

2002-01-01

The surfaces of getter materials are particularly difficult to analyse because of their high chemical reactivity. The results obtained can be strongly influenced by the experimental set-up and procedures. In this paper the experimental influence on the Auger electron spectroscopy results is discussed, based on the measurements of more than 100 different non-evaporable getter (NEG) materials. There are four typical changes in the Auger electron spectra when a NEG becomes activated. The oxygen peak intensity decreases, the shape of the metal peaks changes, the carbon peak shape changes shape and intensity and a chlorine peak occurs. All these changes are affected by instrumental artefacts. The Zr-MNV peak shape changes occurring during the reduction of ZrO2 are well suited to determine the onset of NEG activation, while the slope with which the O-KLL peak intensity decreases in a certain temperature range is a better criterion for the determination of the temperature at which activation is complete. The O-KLL i...

Institute for High Heat Flux Removal (IHHFR). Phases I, II, and III

Energy Technology Data Exchange (ETDEWEB)

Boyd, Ronald D. [Prairie View A& M Univ., TX (United States)

2014-08-31

The IHHFR focused on interdisciplinary applications as it relates to high heat flux engineering issues and problems which arise due to engineering systems being miniaturized, optimized, or requiring increased high heat flux performance. The work in the IHHFR focused on water as a coolant and includes: (1) the development, design, and construction of the high heat flux flow loop and facility; (2) test section development, design, and fabrication; and, (3) single-side heat flux experiments to produce 2-D boiling curves and 3-D conjugate heat transfer measurements for single-side heated test sections. This work provides data for comparisons with previously developed and new single-side heated correlations and approaches that address the single-side heated effect on heat transfer. In addition, this work includes the addition of single-side heated circular TS and a monoblock test section with a helical wire insert. Finally, the present work includes: (1) data base expansion for the monoblock with a helical wire insert (only for the latter geometry), (2) prediction and verification using finite element, (3) monoblock model and methodology development analyses, and (4) an alternate model development for a hypervapotron and related conjugate heat transfer controlling parameters.

Analysis for a PRHRS Condensation Heat Exchanger of the SMART-P Plant

International Nuclear Information System (INIS)

Lee, Kwon-Yeong; Kim, Moo Hwan

2007-01-01

When an emergency such as the unavailability of feedwater or the loss of off-site power arises with SMART-P, the PRHRS passively removes the core decay heat via natural convection. The system is connected to the feedwater and steam pipes and consists of a heat exchanger submerged in a refueling water tank, a compensation tank, and check and isolation valves. The heat exchanger removes the heat from the reactor coolant system through a steam generator via condensation heat transfer to water in the refueling water tank. The compensating tank is pressurized using a nitrogen gas to make up the water volume change in the PRHRS. Before PRHRS operation, nitrogen may be dissolved in the cooling water of the PRHRS. Therefore, during PRHRS operation, nitrogen gas might be generated due to evaporation in the steam generator, which will act as a noncondensable gas in the condensation heat exchanger. The main objective of the present study was to assess the design of a PRHRS condensation heat exchanger (PRHRS HX) by investigating its heat transfer characteristics

Rehabilitation of district heating networks

Energy Technology Data Exchange (ETDEWEB)

Ottosson, Peter [AaF-Energikonsult Syd AB (Sweden)

1996-11-01

Often the choice is between reparation or exchange of a damaged section of the network. If the exchange is based on the wrong assumptions, large sections of undamaged pipelines could be removed. Most important for the district heating company is to decide which strategy to use for the future exchange of the pipelines. Whichever strategy used, it has to based on an assessment of the network and/or assumptions based on that assessment. The question if it is possible extend the life span of the pipelines arises. What is the most economical choice, the exchange or the renovation. (au)

Point, surface and volumetric heat sources in the thermal modelling of selective laser melting

NARCIS (Netherlands)

Yang, Y.; Ayas, C.; Brabazon, Dermot; Naher, Sumsun; Ul Ahad, Inam

2017-01-01

Selective laser melting (SLM) is a powder based additive manufacturing technique suitable for producing high precision metal parts. However, distortions and residual stresses within products arise during SLM because of the high temperature gradients created by the laser heating. Residual stresses

Compact flat-panel gas-gap heat switch operating at 295 K

Science.gov (United States)

Krielaart, M. A. R.; Vermeer, C. H.; Vanapalli, S.

2015-11-01

Heat switches are devices that can change from a thermally conducting (on-) state to an insulating (off-) state whenever the need arises. They enable adaptive thermal management strategies in which cooling rates are altered either spatially or temporally, leading to a substantial reduction in the energy and mass budget of a large range of systems. State-of-the-art heat switches are only rarely employed in thermal system architectures, since they are rather bulky and have a limited thermal performance (expressed as the heat transfer ratio between the on- and off-state heat conductance). Using selective laser melting additive manufacturing technology, also known as 3D printing, we developed a compact flat-panel gas-gap heat switch that offers superior thermal performance, is simpler and more economic to produce and assemble, contains no moving parts, and is more reliable because it lacks welded joints. The manufactured rectangular panel heat switch has frontal device dimensions of 10 cm by 10 cm, thickness of 3.2 mm and weighs just 121 g. An off heat conductance of 0.2 W/K and on-off heat conductance ratio of 38 is observed at 295 K.

Provenance analysis of Roman stone artefacts from sedimentary rocks from the archaeological site near Mošnje, NW Slovenia

Directory of Open Access Journals (Sweden)

Snježana Miletić

2016-08-01

Full Text Available This study deals with the macroscopic and microfacies characterisation of Roman stone artefacts excavated in 2006 from a Roman villa rustica near Mošnje (NW Slovenia with the aim of defiing their provenance. A total of 28 representative fids (querns, mortars, whetstones, tooled and rounded stones, a fragment of stone slab, mosaic tesserae and two architectural elements - one with a relief made of clastic and carbonate sedimentary rocks were examined. Comparison was made with rock samples taken from quarries and gravel bars close to the archaeological site, as well as from larger distance to the site. The majority of artefact sampled is composed of Upper Palaeozoic quartz sandstones, which are found as pebbles in gravel bars close to the archaeological site; while 2 samples were from Quaternary coarse grained clastic rocks which can be found in local glacio-flvial sediments. Other fids were made of four different Mesozoic shallow-water limestones which outcrop in different areas of Central and SW Slovenia. The nearest Lower Jurassic biopelmicritic limestones are found at the western periphery of Ljubljana in Podutik. Cretaceous miliolid limestones and biocalcarenitic limestones with rudists are common in the successions of the Dinaric Carbonate Platform in SW Slovenia (for example, on the Trieste-Komen Plateau, NE Italy and SW Croatia. This indicates that the limestones for architectural elements, stone mortars and tesserae were brought to Mošnje from distant locations. Smaller stone tools are likely to have been made at the location of the archaeological site from material gathered locally, mostly pebbles from clastic rocks, which were accessible and suitable for tooling.

Re-Appraisal of Estrogen Receptor Negative/Progesterone Receptor Positive (ER-/PR+) Breast Cancer Phenotype: True Subtype or Technical Artefact?

Science.gov (United States)

Foley, Niamh M; Coll, J M; Lowery, A J; Hynes, S O; Kerin, M J; Sheehan, M; Brodie, C; Sweeney, K J

2017-09-11

Expression of the ER and PR receptors is routinely quantified in breast cancer as a predictive marker of response to hormonal therapy. Accurate determination of ER and PR status is critical to the optimal selection of patients for targeted therapy. The existence of an ER-/PR+ subtype is controversial, with debate centred on whether this represents a true phenotype or a technical artefact on immunohistochemistry (IHC). The aim of this study was to investigate the true incidence and clinico-pathological features of ER-/PR+ breast cancers in a tertiary referral symptomatic breast unit. Clinico-pathological data were collected on invasive breast cancers diagnosed between 1995 and 2005. IHC for ER and PR receptors was repeated on all cases which were ER-/PR+, with the same paraffin block used for the initial diagnostic testing. Concordance between the diagnostic and repeat IHC was determined using validated testing. Complete data, including ER and PR status were available for 697 patients diagnosed during the study period. On diagnostic IHC, the immunophenotype of the breast tumours was: ER+/PR+ in 396 (57%), ER-/PR- in 157 (23%), ER+/PR- in 88 (12%) and ER-/PR+ in 56 (8.6%) patients. On repeat IHC of 48/56 ER-/PR+ tumours 45.8% were ER+/PR+, 6% were ER+/PR- and 43.7% were ER-/PR- None of the cases were confirmed to be ER-/PR+. The ER-/PR+ phenotypic breast cancer is likely to be the result of technical artefact. Prompt reassessment of patients originally assigned to this subtype who re-present with symptoms should be considered to ensure appropriate clinical management.

Anomalous Posterior Intercostal Arterial Trunk Arising From the Abdominal Aorta

Energy Technology Data Exchange (ETDEWEB)

Jie, Bing, E-mail: jbshh@163.com; Yu, Dong, E-mail: yudong-mail@126.com; Jiang, Sen, E-mail: jasfly77@vip.163.com [Tongji University School of Medicine, Department of Radiology, Shanghai Pulmonary Hospital (China)

2016-04-15

A common trunk of the ipsilateral posterior intercostal artery (PIA) arising from the thoracic aorta is usually an anatomical variation. However, a common trunk of bilateral posterior intercostal arterial trunk (PIAT) arising from the abdominal aorta is rare. It is important to recognize this anatomical variation of PIA when performing interventional radiological procedures. We present a rare case of an anomalous PIAT that originated from the abdominal aorta in a patient with hemoptysis caused by tuberculosis sequelae. Bilateral 4th to 11th PIAs arose from a common trunk and the trunk arising from the posterior aspect of the abdominal aorta at the level of T12/L1 intervertebral space. The pathological right 4th and 5th PIAs and bronchial arteries were embolized. Hemoptysis has been controlled for 3 months.

Tailoring Macroscale Response of Mechanical and Heat Transfer Systems by Topology Optimization of Microstructural Details

DEFF Research Database (Denmark)

Alexandersen, Joe; Lazarov, Boyan Stefanov

2015-01-01

-contrast material parameters is proposed to alleviate the high computational cost associated with solving the discrete systems arising during the topology optimization process. Problems within important engineering areas, heat transfer and linear elasticity, are considered for exemplifying the approach...

Multi-objective convex programming problem arising in multivariate ...

African Journals Online (AJOL)

user

Multi-objective convex programming problem arising in ... However, although the consideration of multiple objectives may seem a novel concept, virtually any nontrivial ..... Solving multiobjective programming problems by discrete optimization.

MYC Amplification in Angiosarcoma Arising from an Arteriovenous Graft Site

Directory of Open Access Journals (Sweden)

Kristen M. Paral

2015-01-01

Full Text Available Angiosarcoma arising in association with an arteriovenous graft (AVG or fistula is a unique clinicopathologic scenario that appears to be gaining recognition in the literature. Among reported cases, none has described high-level MYC gene amplification, a genetic aberration that is increasingly unifying the various clinicopathologic subdivisions of angiosarcoma. We therefore report the MYC gene status in a case of angiosarcoma arising at an AVG site.

Review on Microwave-Matter Interaction Fundamentals and Efficient Microwave-Associated Heating Strategies

Science.gov (United States)

Sun, Jing; Wang, Wenlong; Yue, Qinyan

2016-01-01

Microwave heating is rapidly emerging as an effective and efficient tool in various technological and scientific fields. A comprehensive understanding of the fundamentals of microwave–matter interactions is the precondition for better utilization of microwave technology. However, microwave heating is usually only known as dielectric heating, and the contribution of the magnetic field component of microwaves is often ignored, which, in fact, contributes greatly to microwave heating of some aqueous electrolyte solutions, magnetic dielectric materials and certain conductive powder materials, etc. This paper focuses on this point and presents a careful review of microwave heating mechanisms in a comprehensive manner. Moreover, in addition to the acknowledged conventional microwave heating mechanisms, the special interaction mechanisms between microwave and metal-based materials are attracting increasing interest for a variety of metallurgical, plasma and discharge applications, and therefore are reviewed particularly regarding the aspects of the reflection, heating and discharge effects. Finally, several distinct strategies to improve microwave energy utilization efficiencies are proposed and discussed with the aim of tackling the energy-efficiency-related issues arising from the application of microwave heating. This work can present a strategic guideline for the developed understanding and utilization of the microwave heating technology. PMID:28773355

Dynamic Complexity Study of Nuclear Reactor and Process Heat Application Integration

Energy Technology Data Exchange (ETDEWEB)

J' Tia Patrice Taylor; David E. Shropshire

2009-09-01

Abstract This paper describes the key obstacles and challenges facing the integration of nuclear reactors with process heat applications as they relate to dynamic issues. The paper also presents capabilities of current modeling and analysis tools available to investigate these issues. A pragmatic approach to an analysis is developed with the ultimate objective of improving the viability of nuclear energy as a heat source for process industries. The extension of nuclear energy to process heat industries would improve energy security and aid in reduction of carbon emissions by reducing demands for foreign derived fossil fuels. The paper begins with an overview of nuclear reactors and process application for potential use in an integrated system. Reactors are evaluated against specific characteristics that determine their compatibility with process applications such as heat outlet temperature. The reactor system categories include light water, heavy water, small to medium, near term high-temperature, and far term high temperature reactors. Low temperature process systems include desalination, district heating, and tar sands and shale oil recovery. High temperature processes that support hydrogen production include steam reforming, steam cracking, hydrogen production by electrolysis, and far-term applications such as the sulfur iodine chemical process and high-temperature electrolysis. A simple static matching between complementary systems is performed; however, to gain a true appreciation for system integration complexity, time dependent dynamic analysis is required. The paper identifies critical issues arising from dynamic complexity associated with integration of systems. Operational issues include scheduling conflicts and resource allocation for heat and electricity. Additionally, economic and safety considerations that could impact the successful integration of these systems are considered. Economic issues include the cost differential arising due to an integrated

BOLD responses in somatosensory cortices better reflect heat sensation than pain.

Science.gov (United States)

Moulton, Eric A; Pendse, Gautam; Becerra, Lino R; Borsook, David

2012-04-25

The discovery of cortical networks that participate in pain processing has led to the common generalization that blood oxygen level-dependent (BOLD) responses in these areas indicate the processing of pain. Physical stimuli have fundamental properties that elicit sensations distinguishable from pain, such as heat. We hypothesized that pain intensity coding may reflect the intensity coding of heat sensation during the presentation of thermal stimuli during fMRI. Six 3T fMRI heat scans were collected for 16 healthy subjects, corresponding to perceptual levels of "low innocuous heat," "moderate innocuous heat," "high innocuous heat," "low painful heat," "moderate painful heat," and "high painful heat" delivered by a contact thermode to the face. Subjects rated pain and heat intensity separately after each scan. A general linear model analysis detected different patterns of brain activation for the different phases of the biphasic response to heat. During high painful heat, the early phase was associated with significant anterior insula and anterior cingulate cortex activation. Persistent responses were detected in the right dorsolateral prefrontal cortex and inferior parietal lobule. Only the late phase showed significant correlations with perceptual ratings. Significant heat intensity correlated activation was identified in contralateral primary and secondary somatosensory cortices, motor cortex, and superior temporal lobe. These areas were significantly more related to heat ratings than pain. These results indicate that heat intensity is encoded by the somatosensory cortices, and that pain evaluation may either arise from multimodal evaluative processes, or is a distributed process.

Interaction of pulse laser radiation of 532 nm with model coloration layers for medieval stone artefacts

Energy Technology Data Exchange (ETDEWEB)

Colson, J. [University of Vienna, Department of Physical Chemistry, A-1090 Vienna (Austria); Nimmrichter, J. [Austrian Federal Office for the Care of Monuments, Department for Conservation and Restoration, Arsenal, Objekt 15, Tor 4, A-1030 Vienna (Austria); Kautek, W., E-mail: wolfgang.kautek@univie.ac.at [University of Vienna, Department of Physical Chemistry, A-1090 Vienna (Austria)

2014-05-01

Multilayer polychrome coatings on medieval and Renaissance stone artefacts represent substantial challenges in laser cleaning. Therefore, polychromic models with classical pigments, minium (Pb{sub 2}{sup 2+}Pb{sup 4+}O{sub 4}), zinc white (ZnO), and lead white ((PbCO{sub 3}){sub 2}·Pb(OH){sub 2}) in an acrylic binder, were irradiated with a Q-switched Nd:YAG laser emitting at 532 nm. The studied medieval pigments exhibit strongly varying incubation behaviours directly correlated to their band gap energies. Higher band gaps beyond the laser photon energy of 2.3 eV require more incubative generation of defects for resonant transitions. A matching of the modification thresholds after more than four laser pulses was observed. Laser cleaning with multiple pulsing should not exceed ca. 0.05 J/cm{sup 2} when these pigments coexist in close spatial proximity.

Temporal limits to the archaeological record in arid western NSW, Australia : lessons from OSL and radiocarbon dating of hearths and sediments

International Nuclear Information System (INIS)

Fanning, P.; Holdaway, S.

2001-01-01

The Western NSW Archaeology Program (WNSWAP) has been investigating surface scatters of Aboriginal stone artefacts and associated heat-retainer hearths in arid northwestern NSW, Australia, since 1995. The research combines new methods for documenting and analysing stone artefact scatters with an understanding of geomorphic landscape dynamics to seek insights into spatial and temporal patterns of Aboriginal occupation of the arid margin of Australia during the Late Holocene. The temporal dimension is dealt with in two ways: by radiocarbon determinations on charcoal from the remains of heat-retainer hearths associated with the artefact scatters, and by using optically simulated luminescence (OSL) and radiocarbon determinations from valley fill sediments to develop a chronology of landscape evolution of the valleys in which the artefacts and hearths are found. The heat-retainer hearths produced a record of just less than 2000 years of activity within the valley of Stud Creek, a 30 square km catchment in Sturt National Park. However, the record is discontinuous, with a gap in heat-retainer hearth construction of 200-400 years occurring between about 800 and 1100 y BP. Examination of patterns of erosion and deposition at the places where the hearths were found, and Bayesian statistical analysis of the radiocarbon determinations, demonstrates that this gap is real and not an artefact of the survey protocol. A discontinuous record is also evident when the sediments that comprise the valley fill upon which the hearths and stone artefact scatters are currently lying are examined. Five major sedimentary units can be identified, providing a record of depositional episodes ranging from modern or post-European back to the Late Pleistocene (about 70,000 years). But, in contrast to the record from the remains of the heat-retainer hearths, erosion is the major determinant of the temporal pattern of landscape change that can be reconstructed from this record. Gaps of up to 10

Temporal evolutions of electron temperature and density of turbulently-heated tokamak plasmas in TRIAM-1

Energy Technology Data Exchange (ETDEWEB)

Hiraki, N; Nakamura, K; Nakamura, Y; Itoh, S [Kyushu Univ., Fukuoka (Japan). Research Inst. for Applied Mechanics

1981-04-01

The temporal evolution of the electron temperature and density are measured in a turbulent heating experiment in TRIAM-1. Skin-like profiles of the electron temperature and density are clearly observed. The anomality in the electrical resistivity of the plasma in this skin-layer is estimated, and the plasma heating in this skin-layer is regarded as being due to anomalous joule heating arising from this anomalous resistivity. The ratio of drift velocity to electron thermal velocity in the layer is also calculated, and it is shown that the conditions needed to make the current-driven ion-acoustic instability triggerable are satisfied.

Empiricism Verses Rationalism: Matters Arising in Medical Practice ...

African Journals Online (AJOL)

Empiricism Verses Rationalism: Matters Arising in Medical Practice. ... AFRREV STECH: An International Journal of Science and Technology ... entirely antagonistic to one another, one favoring the senses and the other favoring the mind.

Enhancement of ohmic and stochastic heating by resonance effects in capacitive radio frequency discharges: a theoretical approach.

Science.gov (United States)

Mussenbrock, T; Brinkmann, R P; Lieberman, M A; Lichtenberg, A J; Kawamura, E

2008-08-22

In low-pressure capacitive radio frequency discharges, two mechanisms of electron heating are dominant: (i) Ohmic heating due to collisions of electrons with neutrals of the background gas and (ii) stochastic heating due to momentum transfer from the oscillating boundary sheath. In this work we show by means of a nonlinear global model that the self-excitation of the plasma series resonance which arises in asymmetric capacitive discharges due to nonlinear interaction of plasma bulk and sheath significantly affects both Ohmic heating and stochastic heating. We observe that the series resonance effect increases the dissipation by factors of 2-5. We conclude that the nonlinear plasma dynamics should be taken into account in order to describe quantitatively correct electron heating in asymmetric capacitive radio frequency discharges.

Macroscopic modeling for heat and water vapor transfer in dry snow by homogenization.

Science.gov (United States)

Calonne, Neige; Geindreau, Christian; Flin, Frédéric

2014-11-26

Dry snow metamorphism, involved in several topics related to cryospheric sciences, is mainly linked to heat and water vapor transfers through snow including sublimation and deposition at the ice-pore interface. In this paper, the macroscopic equivalent modeling of heat and water vapor transfers through a snow layer was derived from the physics at the pore scale using the homogenization of multiple scale expansions. The microscopic phenomena under consideration are heat conduction, vapor diffusion, sublimation, and deposition. The obtained macroscopic equivalent model is described by two coupled transient diffusion equations including a source term arising from phase change at the pore scale. By dimensional analysis, it was shown that the influence of such source terms on the overall transfers can generally not be neglected, except typically under small temperature gradients. The precision and the robustness of the proposed macroscopic modeling were illustrated through 2D numerical simulations. Finally, the effective vapor diffusion tensor arising in the macroscopic modeling was computed on 3D images of snow. The self-consistent formula offers a good estimate of the effective diffusion coefficient with respect to the snow density, within an average relative error of 10%. Our results confirm recent work that the effective vapor diffusion is not enhanced in snow.

Cellular schwannoma arising from sigmoid mesocolon presenting ...

African Journals Online (AJOL)

Schwannomas are a type of peripheral nerve sheath tumors with clinically indolent behavior. Though, they can occur anywhere in body, the incidence in retroperitoneum, mediastinum, and pelvis is exceedingly rare. We present a case of a 58‑year‑old female with a massive twisted tumor arising from sigmoid mesocolon.

Cellular Schwannoma Arising from Sigmoid Mesocolon Presenting ...

African Journals Online (AJOL)

Schwannomas are a type of peripheral nerve sheath tumors with clinically indolent behavior. Though, they can occur anywhere in body, the incidence in retroperitoneum, mediastinum, and pelvis is exceedingly rare. We present a case of a 58‑year‑old female with a massive twisted tumor arising from sigmoid mesocolon.

Social Analysis in Development Interventions: Policy Artefact or Constructive Transformation?

Directory of Open Access Journals (Sweden)

SUSANNA PRICE

2012-02-01

Full Text Available Recently attention has focused on the role of social researchers in the processes of construction and transmission of knowledge about global poverty and its reduction. This paper examines some of the formative efforts by pioneering social researchers in development institutions to step into the realm of policy making to construct processes for project preparation and management through social analysis. Before 1970 development planners invoked ‘social' or ‘human' factors only as an excuse to explain away project failures - they designed and implemented development projects in the absence of any strategies or regulatory frameworks for managing their social impacts. Recognizing that project investments represent induced change and constitute a social process in themselves, pioneering social researchers constructed policies and procedures to introduce sociological content and method into the project cycle and so re-order social outcomes. Were such constructs merely policy artefacts? Even as the constructs helped to shift the statements of the development discourse towards ‘people oriented' poverty reduction, new modalities appeared which tested the limits of the agreed methods. Institutions may forget, neglect, contest or re-write the documents if in perceived conflict with the institutional ‘core business'. Yet those pioneering efforts created institutional space for, and understanding of, social analysis, with a measure of flow-on international recognition. Tracking social analysis in several international institutions and in a significant emerging economy, China, this paper highlights not only a history full of lessons to be learned where social analysis is not practiced systematically but also outlines some future challenges.

Probability of US Heat Waves Affected by a Subseasonal Planetary Wave Pattern

Science.gov (United States)

Teng, Haiyan; Branstator, Grant; Wang, Hailan; Meehl, Gerald A.; Washington, Warren M.

2013-01-01

Heat waves are thought to result from subseasonal atmospheric variability. Atmospheric phenomena driven by tropical convection, such as the Asian monsoon, have been considered potential sources of predictability on subseasonal timescales. Mid-latitude atmospheric dynamics have been considered too chaotic to allow significant prediction skill of lead times beyond the typical 10-day range of weather forecasts. Here we use a 12,000-year integration of an atmospheric general circulation model to identify a pattern of subseasonal atmospheric variability that can help improve forecast skill for heat waves in the United States. We find that heat waves tend to be preceded by 15-20 days by a pattern of anomalous atmospheric planetary waves with a wavenumber of 5. This circulation pattern can arise as a result of internal atmospheric dynamics and is not necessarily linked to tropical heating.We conclude that some mid-latitude circulation anomalies that increase the probability of heat waves are predictable beyond the typical weather forecast range.

Exploring young children’s artefact engagements as premises for creating purposeful intergenerational knowledge of digitalized everyday life

DEFF Research Database (Denmark)

Chimirri, Niklas Alexander

The presentation takes its point of departure in a major current expression of the top-down steering rationale in Danish Early Childhood Education and Care, namely the process of digitalization of childcare institutions. While the promotion of using digital artefacts in childcare can be seen...... as reflecting actual and seemingly unavoidable current transformations of the everyday life of adults and children across all societal practices, rendering the political wish to strengthening the digital media literacy of its ‘future citizens’ comprehensible, the ways in which digitalization is promoted...... by state policies accounts little for the ambivalences of digitalized everyday life at home and other relevant contexts. Instead of taking adults’ and children’s digital being seriously and granting opportunities to jointly explore digital artefacts’ possibilities and limitations, hence, childcare...

From artefacts to atoms - A new SI for 2018 to be based on fundamental constants.

Science.gov (United States)

Quinn, Terry

At the 26th General Conference on Weights and Measures (CGPM) in November 2018, it is planned to adopt a new definition of the International System of Units, SI, based on the fixed numerical values of seven defining constants, broadly the fundamental constants of physics. This will be the culmination of more than two hundred years of metrology, instantiating for the first time the original ideas of the creators of the metric system. The key is the replacement of the present definition of the unit of mass, the kilogram artefact of platinum-iridium, by one based on a fixed numerical value of the Planck constant. This article outlines how this has come about, how it will work, why we need a system of measurement that is uniform, accessible world-wide and stable in the long term, and the international structures that now exist to achieve it. Copyright © 2017 Elsevier Ltd. All rights reserved.

Primary chondroid chordoma arising from the petrous temporal bone: a case report

Energy Technology Data Exchange (ETDEWEB)

Lee, Young Uk; Youn, Eun Kyung [Koryo General Hospital, Seoul (Korea, Republic of)

1991-01-15

Chordomas are uncommon tumors which arise from remnants of the primitive notochord. They are situated chiefly in the anterior spinal axis with a predilection for the sacrococcygeal region and the basiocciput. About 50% of chordomas are sacrococcygeal, 35% are intracranial, and 15% arise from a vertebral body. As a histologic variant of chordoma, /chondroid chordoma' was first described by Heffelfinger et al. We present a rare case of primary chondroid chordoma arising from the petrous temporal bone. To our knowledge, only two other cases of this type have been reported earlier.

Primary chondroid chordoma arising from the petrous temporal bone: a case report

International Nuclear Information System (INIS)

Lee, Young Uk; Youn, Eun Kyung

1991-01-01

Chordomas are uncommon tumors which arise from remnants of the primitive notochord. They are situated chiefly in the anterior spinal axis with a predilection for the sacrococcygeal region and the basiocciput. About 50% of chordomas are sacrococcygeal, 35% are intracranial, and 15% arise from a vertebral body. As a histologic variant of chordoma, /chondroid chordoma' was first described by Heffelfinger et al. We present a rare case of primary chondroid chordoma arising from the petrous temporal bone. To our knowledge, only two other cases of this type have been reported earlier

Heat shock factor 1 upregulates transcription of Epstein–Barr Virus nuclear antigen 1 by binding to a heat shock element within the BamHI-Q promoter

International Nuclear Information System (INIS)

Wang, Feng-Wei; Wu, Xian-Rui; Liu, Wen-Ju; Liao, Yi-Ji; Lin, Sheng; Zong, Yong-Sheng; Zeng, Mu-Sheng; Zeng, Yi-Xin; Mai, Shi-Juan; Xie, Dan

2011-01-01

Epstein–Barr virus (EBV) nuclear antigen 1 (EBNA1) is essential for maintenance of the episome and establishment of latency. In this study, we observed that heat treatment effectively induced EBNA1 transcription in EBV-transformed B95-8 and human LCL cell lines. Although Cp is considered as the sole promoter used for the expression of EBNA1 transcripts in the lymphoblastoid cell lines, the RT-PCR results showed that the EBNA1 transcripts induced by heat treatment arise from Qp-initiated transcripts. Using bioinformatics, a high affinity and functional heat shock factor 1 (HSF1)-binding element within the − 17/+4 oligonucleotide of the Qp was found, and was determined by electrophoretic mobility shift assay and chromatin immunoprecipitation assay. Moreover, heat shock and exogenous HSF1 expression induced Qp activity in reporter assays. Further, RNA interference-mediated HSF1 gene silencing attenuated heat-induced EBNA1 expression in B95-8 cells. These results provide evidence that EBNA1 is a new target for the transcription factor HSF1.

Heat shock factor 1 upregulates transcription of Epstein-Barr Virus nuclear antigen 1 by binding to a heat shock element within the BamHI-Q promoter

Energy Technology Data Exchange (ETDEWEB)

Wang, Feng-Wei [The State Key Laboratory of Oncology in South China, Cancer Center, Sun Yat-Sen University, Guangzhou (China); Wu, Xian-Rui [Department of Surgery, Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou (China); Liu, Wen-Ju; Liao, Yi-Ji [The State Key Laboratory of Oncology in South China, Cancer Center, Sun Yat-Sen University, Guangzhou (China); Lin, Sheng [Laboratory of Integrated Biosciences, School of Life Science, Sun Yat-sen University, Guangzhou (China); Zong, Yong-Sheng; Zeng, Mu-Sheng; Zeng, Yi-Xin [The State Key Laboratory of Oncology in South China, Cancer Center, Sun Yat-Sen University, Guangzhou (China); Mai, Shi-Juan, E-mail: maishj@sysucc.org.cn [The State Key Laboratory of Oncology in South China, Cancer Center, Sun Yat-Sen University, Guangzhou (China); Xie, Dan, E-mail: xied@mail.sysu.edu.cn [The State Key Laboratory of Oncology in South China, Cancer Center, Sun Yat-Sen University, Guangzhou (China)

2011-12-20

Epstein-Barr virus (EBV) nuclear antigen 1 (EBNA1) is essential for maintenance of the episome and establishment of latency. In this study, we observed that heat treatment effectively induced EBNA1 transcription in EBV-transformed B95-8 and human LCL cell lines. Although Cp is considered as the sole promoter used for the expression of EBNA1 transcripts in the lymphoblastoid cell lines, the RT-PCR results showed that the EBNA1 transcripts induced by heat treatment arise from Qp-initiated transcripts. Using bioinformatics, a high affinity and functional heat shock factor 1 (HSF1)-binding element within the - 17/+4 oligonucleotide of the Qp was found, and was determined by electrophoretic mobility shift assay and chromatin immunoprecipitation assay. Moreover, heat shock and exogenous HSF1 expression induced Qp activity in reporter assays. Further, RNA interference-mediated HSF1 gene silencing attenuated heat-induced EBNA1 expression in B95-8 cells. These results provide evidence that EBNA1 is a new target for the transcription factor HSF1.

The artefacts of radiochromic film dosimetry with flatbed scanners and their causation by light scattering from radiation-induced polymers.

Science.gov (United States)

Schoenfeld, Andreas A; Poppinga, Daniela; Harder, Dietrich; Doerner, Karl-Joachim; Poppe, Bjoern

2014-07-07

Optical experiments and theoretical considerations have been undertaken in order to understand the causes of the 'orientation effect' and the 'parabola effect', the artefacts impairing the desired light absorption measurement on radiochromic EBT3 films with flatbed scanners. EBT3 films exposed to doses up to 20.9 Gy were scanned with an Epson Expression 10000XL flatbed scanner in landscape and portrait orientation. The horizontally and vertically polarized light components of the scanner were determined, and another Epson Expression 10000XL flatbed scanner was disassembled to examine its optical components. The optical properties of exposed and unexposed EBT3 films were studied with incident polarized and unpolarized white light, and the transmitted red light was investigated for its polarization and scattering properties including the distribution of the scattering angles. Neutral density filters were studied for comparison. Guidance was sought from the theory of light scattering from rod-like macromolecular structures. The drastic dose-dependent variation of the transmitted total light current as function of the orientation of front and rear polarizers, interpreted by light scattering theory, shows that the radiation-induced polymerization of the monomers of EBT3 films produces light scattering oscillators preferably polarized at right angles with the coating direction of the film. The directional distribution of the scattered light is partly anisotropic, with a preferred scattering plane at right angles with the coating direction, indicating light scattering from stacks of coherently vibrating oscillators piled up along the monomer crystals. The polyester carrier film also participates in these effects. The 'orientation' and 'parabola' artefacts due to flatbed scanning of radiochromic films can be explained by the interaction of the polarization-dependent and anisotropic light scattering from exposed and unexposed EBT3 films with the quantitative difference

Estimating stutter rates for Y-STR alleles

DEFF Research Database (Denmark)

Andersen, Mikkel Meyer; Olofsson, Jill Katharina; Mogensen, Helle Smidt

2011-01-01

Stutter peaks are artefacts that arise during PCR amplification of short tandem repeats. Stutter peaks are especially important in forensic case work with DNA mixtures. The aim of the study was primarily to estimate the stutter rates of the AmpFlSTR Yfiler kit. We found that the stutter rates...

The CANDU-PHW generating system waste arisings

International Nuclear Information System (INIS)

Simmons, G.R.

1979-03-01

In this report, the volume of material and level of contained radioactive nuclides are tabulated for wastes arising from four fuel cycles which might be operated in CANDU-PHW (CANada Deuterium Uranium - Pressurized Heavy Water) reactors. The data presented, based on Canadian experience and/or studies, cover the range of conditioned waste volumes which could be expected from steady-state (no growth), CANDU-PHW-powered electrical generating systems. The wastes arising from operation and decommissioning of facilities in each phase of each fuel cycle are estimated. Each fuel cycle is considered to operate in isolation with the data given in terms of quantities per gigawatt-year of electricity produced. Three of the fuel cycles for which data are presented, the natural uranium once-through cycle, the plutonium-enriched uranium cycle (plutonium recycle) and the low-burnup uranium-enriched thorium cycle (thorium and uranium recycle), were studied by INFCE WG.7 (the International Nuclear Fuel Cycle Evaluation, Working Group 7) as fuel cycles 4, 5 and 6. The high-burnup uranium-enriched thorium cycle is included for comparison. INFCE WG.7 selected many common reference parameters which are applied uniformly to all seven INFCE WG.7 reference fuel cycles in determining waste arisings. Where these parameters differ from the data of Canadian origin given in the body of this report, the INFCE WG.7 data are given in an appendix. The waste management costs associated with operation of each INFCE WG.7 reference fuel cycle were calculated and compared by the working group. An arbitrary set of costing parameters and disposal technologies was selected by the working group for application to each of the reference fuel cycles. The waste management and disposal costs for the PHW reactor fuel cycles based on these arbitrary cost parameters are given in an appendix. (author)

Squamous cell carcinoma arising within a maxillary odontogenic keratocyst: A rare occurrence

International Nuclear Information System (INIS)

Jalali, Elnaz; Tadinada, Aditya; Rengasamy, Kandasamy; Ferneini, Elie M.

2017-01-01

Squamous cell carcinoma (SCC) arising within the lining of an odontogenic keratocyst (OKC) is a rare occurrence. Although potentially locally destructive, OKC is a benign odontogenic process that typically presents with clinical and radiographic features characteristic of a benign intraosseous neoplasm. We present the clinical and radiographic features of a maxillary mass that demonstrated SCC arising from the lining of an OKC. Although the initial clinical and radiographic presentation suggested an infection or malignant neoplasm, biopsies revealed an infiltrative well-differentiated SCC contiguous with and arising from the focus of a pre-existing OKC. The patient subsequently underwent a type II hemi-maxillectomy with neoadjuvant chemoradiation. This report discusses the clinical and radiographic features associated with intraosseous malignancies, especially those arising from an otherwise benign odontogenic lesion. While the majority of OKCs are benign, the current report illustrates the potential for carcinomatous transformation within the lining of an OKC

Squamous cell carcinoma arising within a maxillary odontogenic keratocyst: A rare occurrence

Energy Technology Data Exchange (ETDEWEB)

Jalali, Elnaz [Eliray Oral and Maxillofacial Radiology Consulting Services, Miami (United States); Tadinada, Aditya; Rengasamy, Kandasamy; Ferneini, Elie M. [University of Connecticut, School of Dental Medicine, Farmington (United States)

2017-06-15

Squamous cell carcinoma (SCC) arising within the lining of an odontogenic keratocyst (OKC) is a rare occurrence. Although potentially locally destructive, OKC is a benign odontogenic process that typically presents with clinical and radiographic features characteristic of a benign intraosseous neoplasm. We present the clinical and radiographic features of a maxillary mass that demonstrated SCC arising from the lining of an OKC. Although the initial clinical and radiographic presentation suggested an infection or malignant neoplasm, biopsies revealed an infiltrative well-differentiated SCC contiguous with and arising from the focus of a pre-existing OKC. The patient subsequently underwent a type II hemi-maxillectomy with neoadjuvant chemoradiation. This report discusses the clinical and radiographic features associated with intraosseous malignancies, especially those arising from an otherwise benign odontogenic lesion. While the majority of OKCs are benign, the current report illustrates the potential for carcinomatous transformation within the lining of an OKC.

Heat transport in McMurdo Sound first-year fast ice

Science.gov (United States)

Trodahl, H. J.; McGuinness, M. J.; Langhorne, P. J.; Collins, K.; Pantoja, A. E.; Smith, I. J.; Haskell, T. G.

2000-05-01

We have monitored the temperature field within first-year sea ice in McMurdo Sound over two winter seasons, with sufficient resolution to determine the thermal conductivity from the thermal waves propagating down through the ice. Data reduction has been accomplished by direct reference to energy conservation, relating the rate of change of the internal energy density to the divergence of the heat current density. Use of this procedure, rather than the wave attenuation predicted by the thermal diffusion equation, avoids difficulties arising from a strongly temperature dependent thermal diffusivity. The thermal conductivity is an input parameter for ice growth and climate models, and the values commonly used in the models are predicted to depend on temperature, salinity, and the volume fraction of air. The present measurements were performed at depths in the ice where the air volume is small and the salinity is nearly constant, and they permit the determination of the absolute magnitude of the thermal conductivity and its temperature dependence. The weak temperature dependence is similar to that predicted by the models in the literature, but the magnitude is smaller by ˜10% than the predicted value most commonly used in climate and sea ice models. In the first season we find an additional scatter in the results at driving temperature gradients larger than ˜10-15 °C/m. We suggest that the scatter arises from a nonlinear contribution to the heat current, possibly associated with the onset of convective motion in brine inclusions. Episodic convective events are also observed. We have further determined the growth rate of the ice and compared it with the rate explained by the heat flux from the ice-water interface. The data show a sudden rise of growth rate, without a rise in heat flux through the ice, which coincides in time and depth with the appearance of platelet ice. Finally, we discuss the observation of radiative solar heating at depth in the ice and

Changes Arising from Conservation Peas

Directory of Open Access Journals (Sweden)

Lucica Nistor

2010-05-01

Full Text Available It was established that the amount of canned food products depends on the one hand the amount of raw material and on the other processing conditions. To ensure a high food value of canned products, in establishing the technological process should take termolability account both the solubility and valuable substances that some vitamins, minerals, carbohydrates and nitrogenous substances. If the solubility of the substances determined, in particular, losses during the preliminary operations of washing, scalding, cooling, causes losses both during thermolability cooked, and during sterilization. The vitamins, which recorded the largest losses during the technological process, are vitamin C followed by B1 and B2 lesser extent. These vitamins, in addition to being water soluble, are thermo labile, but termolability depends largely on conditions of heating. Thus, vitamin C is destroyed in the presence of air even at a temperature of 50 ° C, but in the absence of air and acid, its resistance to heat action is much greater, mentioned that the acidic environment increases and the strength of vitamin B1. In some cases, a short heating can contribute to keeping the vitamins in the product by removing air from the tissue and inactivation of enzymes that catalyzes the oxidation of vitamin C (ascorbinase.

Occupancy statistics arising from weighted particle rearrangements

International Nuclear Information System (INIS)

Huillet, Thierry

2007-01-01

The box-occupancy distributions arising from weighted rearrangements of a particle system are investigated. In the grand-canonical ensemble, they are characterized by determinantal joint probability generating functions. For doubly non-negative weight matrices, fractional occupancy statistics, generalizing Fermi-Dirac and Bose-Einstein statistics, can be defined. A spatially extended version of these balls-in-boxes problems is investigated

High-frequency current application in industry for heating of non-metallic materials. Session 4 N. 4. 2

Energy Technology Data Exchange (ETDEWEB)

Bezmenov, F V; Dashkevich, I P; Dobrovolskaya, V I; Fedorova, I G; Shamov, A N; Vasiliev, A S

1984-01-01

Large scale industrial development of induction heating requires high operating efficiencies. This resulted in extending the research and development in the fiels of static frequency inverters and its circuits. Medium frequency sub-stations for centralized feeding of heating units are widely introduced into industry. Techno-economical parameters of induction heating strongly depend of proper choice and monitoring of heating conditions. Systems of analog and digital control for electro-heat processes and for power source operational conditions are considered. Large attention is drawn to the development of high capacity radio frequency power source for welding. Some questions arising from the computer design techniques adopted for industrial heating uits and power sources are described. Modes of combined solution of two and three-dimensional systems as well as hydrodynamic problems are presented.

Role of quantum correlations in light-matter quantum heat engines

Science.gov (United States)

Barrios, G. Alvarado; Albarrán-Arriagada, F.; Cárdenas-López, F. A.; Romero, G.; Retamal, J. C.

2017-11-01

We study a quantum Otto engine embedding a working substance composed of a two-level system interacting with a harmonic mode. The physical properties of the substance are described by a generalized quantum Rabi model arising in superconducting circuit realizations. We show that light-matter quantum correlation reduction during the hot bath stage and adiabatic stages act as an indicator for enhanced work extraction and efficiency, respectively. Also, we demonstrate that the anharmonic spectrum of the working substance has a direct impact on the transition from heat engine into refrigerator as the light-matter coupling is increased. These results shed light on the search for optimal conditions in the performance of quantum heat engines.

External costs and taxes in heat supply systems

International Nuclear Information System (INIS)

Karlsson, Aasa; Gustavsson, Leif

2003-01-01

A systems approach was used to compare different heating systems from a consumer perspective. The whole energy system was considered from natural resources to the required energy services. District heating, electric heat pumps, electric boilers, natural-gas-, oil- or pellet-fired local boilers were considered when supplying heat to a detached house. The district heat production included wood-chip-fired and natural-gas-fired cogeneration plants. Electricity other than cogenerated electricity was produced in wood-chip- and natural-gas-fired stand-alone power plants. The analysis includes four tax scenarios, as well as the external cost of environmental and health damage arising from energy conversion emission based on the ExternE study of the European Commission. The most cost-efficient systems were the natural-gas and oil boiler systems, followed by the heat pump and district heating systems, when the external cost and taxes were excluded. When including the external costs of CO 2 emission, the wood-fuel-based systems were much more cost efficient than the fossil-fuel-based systems, also when CO 2 capture and storage were applied. The external costs are, however, highly uncertain. Taxes steer towards lowering energy use and lowering CO 2 emission if they are levied solely on all the fossil-fuel-related emission and fuel use in the systems. If consumer electricity and heat taxes are used, the taxes have an impact on the total cost, regardless of the fuel used, thereby benefiting fuel-based local heating systems. The heat pump systems were the least affected by taxes, due to their high energy efficiency. The electric boiler systems were the least cost-efficient systems, also when the external cost and taxes were included

Position-history and spin-history artifacts in fMRI time-series

NARCIS (Netherlands)

Muresan, L; Renken, R; Roerdink, JBTM; Duifhuis, H; Clough, AN; Chen, CT

2002-01-01

What is the impact of the spin history and position history on signal intensity after the alignment of acquired volumes? This question arises in many fMRI studies. We will focus on spin-history artefacts generated by the position-history of the scanned object. In fMRI an object is driven to steady

Improvements in or relating to heat exchangers

International Nuclear Information System (INIS)

Linning, D.L.

1976-01-01

A 'tube-in-shell' heat exchanger is described for effecting heat exchange between liquid metal and water. In conventional heat exchangers of this type a condition can arise wherein Na passing through the tube plate at the water inlet end of the heat exchanger may be above the saturation temperature of the water, and although resultant boiling of the water in the region of the tube plate would tend to counter stagnation there is a possibility that sub-cooled boiling associated with stagnation may occur in the central area of the tube plate, and this could be the source of corrosion. The design of heat exchanger described is directed towards a solution of this problem. The heat exchanger comprises an elongated shell having two spaced transverse tube plates sealed to the shell so as to provide end and intermediate chambers. A bundle of spaced parallel heat exchange tubes extends between the tube plates, interconnecting the end chambers with an inlet port for liquid metal flow to one of the end chambers and an outlet port for liquid metal flow from the other of the end chambers, and inlet and outlet ports for flow of water through the intermediate chamber, these ports being at opposite ends of the intermediate chamber. The intermediate chamber has a tube closed to liquid metal flow extending between the tube plates, this tube having an inlet port for water adjacent to the tube plate at the inlet region of the intermediate chamber and an outlet port at the outlet region. This tube has open ends and is laterally supported by neighbouring heat exchange tubes, or alternatively may have closed ends and be end supported by penetration of the tube plates, the inlet and outlet ports for flow of water being perforations in the wall of the tube. (U.K.)

Portable XRF on Prehistoric Bronze Artefacts: Limitations and Use for the Detection of Bronze Age Metal Workshops

DEFF Research Database (Denmark)

Nørgaard, Heide Wrobel

2017-01-01

sections were analysed using a scanning electron microscope (SEM). Results from the corrosion crust of copper-tin alloys, and the change measured within the elemental composition from the bulk metal to the surface, greatly influenced the interpretation of the second data set, which was measured using......Two different scientific analyses—one destructive and one non destructive—were conducted on two separate groups of bronze ornaments dating from 1500–1100 BC to investigate, amongst other traits, the metal composition of their copper-tin alloys. One group of artefacts was sampled, and polished thin...... a handheld X-ray fluorescence (XRF) device. The surface of corroded bronze ornaments consists mostly of copper carbonates, oxides, and chlorides. Chemical processes, such as decuprification, change the element composition in such a manner that the original alloy cannot be traced with a non-destructive method...

Malignancy arising within cutaneous tattoos: case of dermatofibrosarcoma protuberans and review of literature.

Science.gov (United States)

Reddy, Kavitha K; Hanke, C William; Tierney, Emily P

2011-08-01

Dermatofibrosarcoma protuberans (DFSP) is an uncommon tumor of the skin with high rates of local recurrence. Several reports describe a frequent history of local trauma. In one prior case, a DFSP arising in a tattoo site has been reported. Mohs micrographic surgery (MMS) has been used successfully for treatment. To present a case of dermatofibrosarcoma protuberans arising in the site of a prior and current tattoo, and treated with Mohs micrographic surgery. We present findings of a case of a DFSP arising in a tattoo and a review of Medline literature on the association between tattoos and cutaneous malignancy, and treatment of DFSP with MMS. Review of the literature confirms multiple reports of DFSP arising in sites of local trauma, as well as malignancies arising in sites of tattoos. The recurrence rate for MMS treatment of DFSP (0-6.6%) was found to be significantly lower than that for patients treated with wide local excision (13% to 95%). DFSP should be considered in the differential diagnosis of neoplasms arising within areas of tattoos. Sites of local trauma and tattoos may show predilection for benign and malignant changes and should be evaluated during regular skin exams. Review of the literature confirms MMS is an ideal treatment modality for DFSP as the tumor often extends far beyond clinical margins.

Two cases of basal cell carcinoma arising from chronic radiation dermatitis

International Nuclear Information System (INIS)

Wakamori, Takeshi; Takenaka, Hideya; Ueda, Eiichiro; Katoh, Norito; Kishimoto, Saburo

2003-01-01

A 48-year-old female and a 51-year-old male with basal cell carcinoma (BCC) arising from chronic radiation dermatitis are reviewed. They are treated with radiotherapy for hemangioma on their right cheek in their childhood. Review in the literature showed high incidence of the histological diagnosis of malignant skin tumors arising from chronic radiation dermatitis are follows: squamous cell carcinoma (SCC), BCC, sarcoma, and Bowen's disease. (author)

Transient thermal stresses in circular cylinder under intermittently sudden heat generation

International Nuclear Information System (INIS)

Sugano, Y.; Saito, K.; Takeuti, Y.

1975-01-01

The thermal stresses associated with the transient temperature distribution arising in a circular cylinder under intermittently changing sudden heat generation over a finite band and with heat loss to a surrounding medium on the remainder of the cylinder surface are exactly analysed. For the first time the temperature field in a circular cylinder under sudden heat generation over a finite band of the cylinder surface is determined by combined use of Fourier cosine, Laplace transforms in axial position and time, respectively. Secondly it is assumed that the temperature fields in a circular cylinder subjected to heat generation Qsub(i) (i=0, 1, 2, ...) independently over a finite band are given by T 0 (r,z,t), T 1 (r,z,t), T 2 (r,z,t),... respectively. Tsub(i)(r,z,t) indicates the temperature field before the i-th heat generation Qsub(i). The thermal stresses associated with the temperature field described above are analysed by using the Hoyle stress functions. Numerical calculations are carried out for the extensive case of the ratio of the heat-generating length to the diameter of cylinder. It is found that the time in which the maximum stresses occur on the cylinder surface does not depend on the heat-generating length-to-diameter ratio

Flow and heat transfer behaviour of nanofluids in microchannels

Directory of Open Access Journals (Sweden)

James Bowers

2018-04-01

Full Text Available Flow and heat transfer of aqueous based silica and alumina nanofluids in microchannels were experimentally investigated. The measured friction factors were higher than conventional model predictions at low Reynolds numbers particularly with high nanoparticle concentrations. A decrease in the friction factor was observed with increasing Reynolds number, possibly due to the augmentation of nanoparticle aggregate shape arising from fluid shear and alteration of local nanoparticle concentration and nanofluid viscosity. Augmentation of the silica nanoparticle morphology by fluid shear may also have affected the friction factor due to possible formation of a core/shell structure of the particles. Measured thermal conductivities of the silica nanofluids were in approximate agreement with the Maxwell-Crosser model, whereas the alumina nanofluids only showed slight enhancements. Enhanced convective heat transfer was observed for both nanofluids, relative to their base fluids (water, at low particle concentrations. Heat transfer enhancement increased with increasing Reynolds number and microchannel hydraulic diameter. However, the majority of experiments showed a larger increase in pumping power requirements relative to heat transfer enhancements, which may hinder the industrial uptake of the nanofluids, particularly in confined environments, such as Micro Electro-Mechanical Systems (MEMS. Keywords: Nanofluid, Microchannel, Heat transfer, Pressure drop, Friction factor, Thermal conductivity, Viscosity

Comparative Laser Spectroscopy Diagnostics for Ancient Metallic Artefacts Exposed to Environmental Pollution

Directory of Open Access Journals (Sweden)

Łukasz Ciupiński

2010-05-01

Full Text Available Metal artworks are subjected to corrosion and oxidation processes due to reactive agents present in the air, water and in the ground that these objects have been in contact with for hundreds of years. This is the case for archaeological metals that are recovered from excavation sites, as well as artefacts exposed to polluted air. Stabilization of the conservation state of these objects needs precise diagnostics of the accrued surface layers and identification of original, historical materials before further protective treatments, including safe laser cleaning of unwanted layers. This paper presents analyses of the chemical composition and stratigraphy of corrosion products with the use of laser induced breakdown spectroscopy (LIBS and Raman spectroscopy. The discussion of the results is supported by material studies (SEM-EDS, XRF, ion-analyses. The tests were performed on several samples taken from original objects, including copper roofing from Wilanów Palace in Warsaw and Karol Poznański Palace in Łódź, bronze decorative figures from the Wilanów Palace gardens, and four archaeological examples of old jewellery (different copper alloys. Work has been performed as a part of the MATLAS project in the frames of EEA and Norway Grants (www.matlas.eu and the results enable the comparison of the methodology and to elaborate the joint diagnostic procedures of the three project partner independent laboratories.

Comparative Laser Spectroscopy Diagnostics for Ancient Metallic Artefacts Exposed to Environmental Pollution

Science.gov (United States)

Ciupiński, Łukasz; Fortuna-Zaleśna, Elżbieta; Garbacz, Halina; Koss, Andrzej; Kurzydłowski, Krzysztof J.; Marczak, Jan; Mróz, Janusz; Onyszczuk, Tomasz; Rycyk, Antoni; Sarzyński, Antoni; Skrzeczanowski, Wojciech; Strzelec, Marek; Zatorska, Anna; Żukowska, Grażyna Z.

2010-01-01

Metal artworks are subjected to corrosion and oxidation processes due to reactive agents present in the air, water and in the ground that these objects have been in contact with for hundreds of years. This is the case for archaeological metals that are recovered from excavation sites, as well as artefacts exposed to polluted air. Stabilization of the conservation state of these objects needs precise diagnostics of the accrued surface layers and identification of original, historical materials before further protective treatments, including safe laser cleaning of unwanted layers. This paper presents analyses of the chemical composition and stratigraphy of corrosion products with the use of laser induced breakdown spectroscopy (LIBS) and Raman spectroscopy. The discussion of the results is supported by material studies (SEM-EDS, XRF, ion-analyses). The tests were performed on several samples taken from original objects, including copper roofing from Wilanów Palace in Warsaw and Karol Poznański Palace in ŁódŸ, bronze decorative figures from the Wilanów Palace gardens, and four archaeological examples of old jewellery (different copper alloys). Work has been performed as a part of the MATLAS project in the frames of EEA and Norway Grants (www.matlas.eu) and the results enable the comparison of the methodology and to elaborate the joint diagnostic procedures of the three project partner independent laboratories. PMID:22399915

A comparison of prone SPET and left lateral (decubitus) planar imaging for inferior wall attenuation artefact in 201Tl myocardial imaging

International Nuclear Information System (INIS)

O'Donnell, M.; Jenkin, B.; Van Every, B.; Kelly, M.J.; Kalff, V.

1999-01-01

Full text: Inferior wall attenuation artefacts are a major problem in supine SPET (S-S) myocardial perfusion imaging. SPET imaging with the patient lying in the prone position (P-S) and left lateral planar imaging with the patient lying in the right lateral decubitus position (LL) ameliorate this artefact. This study attempts to define the clinical role of P-S and LL imaging in characterizing S-S inferior wall defects. 21 patients with an inferior wall defect on S-S then had LL and rapid P-S imaging. All images were performed with a GE Optima NX gamma camera using GENIE acquisition and processing. All SPETs used 16 stops (32 frames) through 90 deg, with 40 s per stop for SS and 14 s per stop for P-S. LL images were acquired for 150 s. All images were assessed for adequacy and inferior wall scored for 0 = no, 1 mild, 2 moderate and 3 = severe defects. Statistical analysis was performed using the Wilcoxon rank sum test for matched pairs. All images were adequate for analysis. Significantly fewer defects were seen in P-S vs S-S, LL vs S-S (P 0.88); however; there was a difference (P < 0.05) in the subgroup (n = 7) with moderate defects on S-S imaging but no LL defect. In conclusion, most inferior wall defects seen on S-S imaging can be attributed to either attenuation or true perfusion defects with the use of LL imaging. Prone imaging may only be helpful where the inferior defect is of moderate severity but no LL defect is seen

Developing occupational chronologies for surface archaeological deposits from heat retainer hearths on Pine Point and Langwell stations, Far Western New South Wales, Australia

International Nuclear Information System (INIS)

Shiner, J.

2003-01-01

The archaeological record of arid Australia is dominated by deflated distributions of stone artefacts and heat retainer hearths covering many thousands of square metres. These deposits have often been over-looked by archaeologists in preference for stratified deposits, which are regarded as more appropriate for investigating temporal issues. In recent years this situation had slowly begun to change with the large-scale dating of heat retainer hearths from surface contexts. The work of of Fanning and Holdaway (2001) and Holdaway et al. (2002) in Far Western New South Wales has demonstrated that through the dating of large numbers of hearths it is possible to develop occupational chronologies for surface deposits. At a wider landscape scale these chronologies reflect the timing and tempo of the occupation of different places. A major component of my doctoral fieldwork on Pine Point and Langwell stations, 50 km south of Broken Hill in Western New South Wales, aimed to establish occupational chronologies from hearths for surface archaeological distributions. This paper reports on radiocarbon results from this investigation. (author). 6 refs., 2 figs., 1 tab

Critical heat flux and exit film flow rate in a flow boiling system

International Nuclear Information System (INIS)

Ueda, Tatsuhiro; Isayama, Yasushi

1981-01-01

The critical heat flux in a flowing boiling system is an important problem in the evaporating tubes with high thermal load such as nuclear reactors and boilers, and gives the practical design limit. When the heat flux in uniformly heated evaporating tubes is gradually raised, the tube exit quality increases, and soon, the critical heat flux condition arises, and the wall temperature near tube exit rises rapidly. In the region of low exit quality, the critical heat flux condition is caused by the transition from nucleating boiling, and in the region of high exit quality, it is caused by dry-out. But the demarcation of both regions is not clear. In this study, for the purpose of obtaining the knowledge concerning the critical heat flux condition in a flowing boiling system, the relation between the critical heat flux and exit liquid film flow rate was examined. For the experiment, a uniformly heated vertical tube supplying R 113 liquid was used, and the measurement in the range of higher heating flux and mass velocity than the experiment by Ueda and Kin was carried out. The experimental setup and experimental method, the critical heat flux and exit quality, the liquid film flow rate at heating zone exit, and the relation between the critical heat flux and the liquid film flow rate at exit are described. (Kako, I.)

Independent component analysis-based artefact reduction: application to the electrocardiogram for improved magnetic resonance imaging triggering

International Nuclear Information System (INIS)

Oster, Julien; Pietquin, Olivier; Felblinger, Jacques; Abächerli, Roger; Kraemer, Michel

2009-01-01

Electrocardiogram (ECG) is required during magnetic resonance (MR) examination for monitoring patients under anaesthesia or with heart diseases and for synchronizing image acquisition with heart activity (triggering). Accurate and fast QRS detection is therefore desirable, but this task is complicated by artefacts related to the complex MR environment (high magnetic field, radio-frequency pulses and fast switching magnetic gradients). Specific signal processing has been proposed, whether using specific MR QRS detectors or ECG denoising methods. Most state-of-the-art techniques use a connection to the MR system for achieving their task, which is a major drawback since access to the MR system is often restricted. This paper introduces a new method for on-line ECG signal enhancement, called ICARE, which takes advantage of using multi-lead ECG and does not require any connection to the MR system. It is based on independent component analysis (ICA) and applied in real time. This algorithm yields accurate QRS detection for efficient triggering

Maintained functionality of an implantable radiotelemetric blood pressure and heart rate sensor after magnetic resonance imaging in rats

International Nuclear Information System (INIS)

Nölte, I; Boll, H; Figueiredo, G; Groden, C; Brockmann, M A; Gorbey, S; Lemmer, B

2011-01-01

Radiotelemetric sensors for in vivo assessment of blood pressure and heart rate are widely used in animal research. MRI with implanted sensors is regarded as contraindicated as transmitter malfunction and injury of the animal may be caused. Moreover, artefacts are expected to compromise image evaluation. In vitro, the function of a radiotelemetric sensor (TA11PA-C10, Data Sciences International) after exposure to MRI up to 9.4 T was assessed. The magnetic force of the electromagnetic field on the sensor as well as radiofrequency (RF)-induced sensor heating was analysed. Finally, MRI with an implanted sensor was performed in a rat. Imaging artefacts were analysed at 3.0 and 9.4 T ex vivo and in vivo. Transmitted 24 h blood pressure and heart rate were compared before and after MRI to verify the integrity of the telemetric sensor. The function of the sensor was not altered by MRI up to 9.4 T. The maximum force exerted on the sensor was 273 ± 50 mN. RF-induced heating was ruled out. Artefacts impeded the assessment of the abdomen and thorax in a dead rat, but not of the head and neck. MRI with implanted radiotelemetric sensors is feasible in principal. The tested sensor maintains functionality up to 9.4 T. Artefacts hampered abdominal and throacic imaging in rats, while assessment of the head and neck is possible

Experimental Analysis of a Heat Cost Allocation Method for Apartment Buildings

Directory of Open Access Journals (Sweden)

Fabio Saba

2017-03-01

Full Text Available The correct estimate of individual thermal energy consumptions, and consequently, a fair heat cost allocation among the residents of apartment buildings with centralized heating systems, represents an important driving force towards energy saving, energy efficiency and the reduction of pollutant emissions. Nowadays, in those contexts where direct heat meters cannot be used because of the layout of the hot water distribution system, electronic Heat Cost Allocators (HCAs have the highest market share for the assessment of individual thermal energy consumptions. The uncertainty associated with the parameterization of heat cost allocation devices and the installation effects arising in real applications can negatively affect the accuracy of these devices, as far as the estimation of the individual fractions of thermal energy consumption is concerned. This work deals with the experimental analysis of a novel heat cost allocation method for apartment buildings and its comparison with conventional HCAs. The method allows the indirect estimation of the thermal energy exchanged by water radiators without the need for surface temperature measurements, reducing some of the drawbacks associated with the on-site installation. The experimental analysis was carried out in a full-scale central heating system test facility available at the Italian National Metrology Institute (INRIM and characterized by SI-traceable direct heat meters installed on each water radiator.

Distance-driven projection and backprojection in three dimensions

International Nuclear Information System (INIS)

De Man, Bruno; Basu, Samit

2004-01-01

Projection and backprojection are operations that arise frequently in tomographic imaging. Recently, we proposed a new method for projection and backprojection, which we call distance-driven, and that offers low arithmetic cost and a highly sequential memory access pattern. Furthermore, distance-driven projection and backprojection avoid several artefact-inducing approximations characteristic of some other methods. We have previously demonstrated the application of this method to parallel and fan beam geometries. In this paper, we extend the distance-driven framework to three dimensions and demonstrate its application to cone beam reconstruction. We also present experimental results to demonstrate the computational performance, the artefact characteristics and the noise-resolution characteristics of the distance-driven method in three dimensions

Micro-computerised tomography optimisation for the measurement of bone mineral density around titanium dental implants

International Nuclear Information System (INIS)

Park, C.; Swain, M.; Duncan, W.

2010-01-01

Titanium dental implants (screws) are commonly used to replace missing teeth by forming a biological union with bone ('osseointegration'). Micro-computerised tomography (μCT) may be useful for measuring bone mineral density around dental implants. Major issues arise because of various artefacts that occur with polychromatic X-rays associated bench type instruments that may compromise interpretation of the observations. In this study various approaches to minimise artefacts such as; beam hardening, filtering and edge effects are explored with a homogeneous polymeric material, Teflon, with and without an implant present. The implications of the limitations of using such polychromatic μCT systems to quantify bone mineral density adjacent to the implant are discussed. (author)

Irradiation treatment for the protection and conservation of cultural heritage artefacts in Croatia

International Nuclear Information System (INIS)

Katusin-Razem, Branka; Razem, Dusan; Braun, Mario

2009-01-01

The application of irradiation treatment for the protection of cultural heritage artefacts in Croatia was made possible by the development of radiation processing procedures at the Radiation Chemistry and Dosimetry Laboratory of the Ruder Boskovic Institute. After the upgrading of the 60 Co gamma irradiation source in the panoramic irradiation facility in 1983 it became possible to perform both research and pilot plant-scale irradiations for sterilization, pasteurization and decontamination of various materials, including medical supplies, pharmaceuticals, cosmetics and foods, but also for disinfestation of cultural heritage artefects. The demand for irradiation treatment of cultural heritage objects has particularly increased as the increasing number of these objects, especially polychromic wooden sculptures, were requiring salvation, restauration and conservation as a consequence of direct and indirect damages inflicted to them during the war in Croatia, 1991-1995. The irradiation facility at the Ruder Boskovic Institute is briefly described and an account of its fifteen years' activities in the irradiation treatment of cultural heritage objects is given. Some case studies performed in cooperation with the Croatian Conservation Institute and other interested parties are presented, as well as some cases of protective and curative treatments for disinfestation and decontamination. International cooperations and activities are also mentioned.

Irradiation treatment for the protection and conservation of cultural heritage artefacts in Croatia

Energy Technology Data Exchange (ETDEWEB)

Katusin-Razem, Branka [Department of Chemistry, Ruder Boskovic Institute, Bijenicka cesta 54, P.O. Box 180, HR-10002 Zagreb (Croatia)], E-mail: brazem@irb.hr; Razem, Dusan [Department of Chemistry, Ruder Boskovic Institute, Bijenicka cesta 54, P.O. Box 180, HR-10002 Zagreb (Croatia); Braun, Mario [Croatian Conservation Institute, Zagreb (Croatia)

2009-07-15

The application of irradiation treatment for the protection of cultural heritage artefacts in Croatia was made possible by the development of radiation processing procedures at the Radiation Chemistry and Dosimetry Laboratory of the Ruder Boskovic Institute. After the upgrading of the {sup 60}Co gamma irradiation source in the panoramic irradiation facility in 1983 it became possible to perform both research and pilot plant-scale irradiations for sterilization, pasteurization and decontamination of various materials, including medical supplies, pharmaceuticals, cosmetics and foods, but also for disinfestation of cultural heritage artefects. The demand for irradiation treatment of cultural heritage objects has particularly increased as the increasing number of these objects, especially polychromic wooden sculptures, were requiring salvation, restauration and conservation as a consequence of direct and indirect damages inflicted to them during the war in Croatia, 1991-1995. The irradiation facility at the Ruder Boskovic Institute is briefly described and an account of its fifteen years' activities in the irradiation treatment of cultural heritage objects is given. Some case studies performed in cooperation with the Croatian Conservation Institute and other interested parties are presented, as well as some cases of protective and curative treatments for disinfestation and decontamination. International cooperations and activities are also mentioned.

Magnetic-field asymmetry of nonlinear thermoelectric and heat transport

International Nuclear Information System (INIS)

Hwang, Sun-Yong; Sánchez, David; López, Rosa; Lee, Minchul

2013-01-01

Nonlinear transport coefficients do not obey, in general, reciprocity relations. We here discuss the magnetic-field asymmetries that arise in thermoelectric and heat transport of mesoscopic systems. Based on a scattering theory of weakly nonlinear transport, we analyze the leading-order symmetry parameters in terms of the screening potential response to either voltage or temperature shifts. We apply our general results to a quantum Hall antidot system. Interestingly, we find that certain symmetry parameters show a dependence on the measurement configuration. (paper)

Clinical outcomes of patients with clear cell and endometrioid ovarian cancer arising from endometriosis.

Science.gov (United States)

Paik, E Sun; Kim, Tae Joong; Choi, Chel Hun; Kim, Byoung Gie; Bae, Duk Soo; Lee, Jeong Won

2018-03-01

The aim of this investigation is to compare outcomes of patients according to the presence of cancer arising from endometriosis in ovarian clear cell carcinoma (CCC) and endometrioid carcinoma (EC). This study retrospectively investigated 224 CCC and EC patients treated in Samsung Medical Center from 2001 to 2015 to identify cancer arising from endometriosis according to Sampson and Scott criteria. Propensity score matching was performed to compare patients arising from endometriosis to patients without endometriosis (ratio 1:1) according to stage, age, lymph node metastasis (LNM), cancer antigen (CA)-125 level, and residual status after debulking surgery. Forty-five cases arising from endometriosis were compared with 179 cases without endometriosis. CCC and EC arising from endometriosis tended to present with early age (mean, 45.2 vs. 49.2 years; p=0.003), early-stage (stages I and II, 92.7% vs. 62.3%; p<0.001), lower CA-125 level (mean, 307.1 vs. 556.7; p=0.041), higher percentages of no gross residual disease after surgery (87.8% vs.56.8%; p=0.001), and higher percentages of negative LNM (82.9% vs. 59.0%; p=0.008) compared to cases without endometriosis. Kaplan-Meier curves for progression-free survival (PFS) and overall survival (OS) showed better outcomes for groups with cancer arising from endometriosis (p=0.014 for PFS; and p=0.010 for OS). However, the association with endometriosis was not significant in multivariate analysis. Also, after propensity score matching, survival differences between the 2 groups were not significant. CCC and EC arising from endometriosis are diagnosed at an earlier age and stage. However, cancer arising from endometriosis was not a significant prognostic factor. Copyright © 2018. Asian Society of Gynecologic Oncology, Korean Society of Gynecologic Oncology

The Australasian Resuscitation in Sepsis Evaluation (ARISE) trial statistical analysis plan.

Science.gov (United States)

Delaney, Anthony P; Peake, Sandra L; Bellomo, Rinaldo; Cameron, Peter; Holdgate, Anna; Howe, Belinda; Higgins, Alisa; Presneill, Jeffrey; Webb, Steve

2013-09-01

The Australasian Resuscitation in Sepsis Evaluation (ARISE) study is an international, multicentre, randomised, controlled trial designed to evaluate the effectiveness of early goal-directed therapy compared with standard care for patients presenting to the emergency department with severe sepsis. In keeping with current practice, and considering aspects of trial design and reporting specific to non-pharmacological interventions, our plan outlines the principles and methods for analysing and reporting the trial results. The document is prepared before completion of recruitment into the ARISE study, without knowledge of the results of the interim analysis conducted by the data safety and monitoring committee and before completion of the two related international studies. Our statistical analysis plan was designed by the ARISE chief investigators, and reviewed and approved by the ARISE steering committee. We reviewed the data collected by the research team as specified in the study protocol and detailed in the study case report form. We describe information related to baseline characteristics, characteristics of delivery of the trial interventions, details of resuscitation, other related therapies and other relevant data with appropriate comparisons between groups. We define the primary, secondary and tertiary outcomes for the study, with description of the planned statistical analyses. We have developed a statistical analysis plan with a trial profile, mock-up tables and figures. We describe a plan for presenting baseline characteristics, microbiological and antibiotic therapy, details of the interventions, processes of care and concomitant therapies and adverse events. We describe the primary, secondary and tertiary outcomes with identification of subgroups to be analysed. We have developed a statistical analysis plan for the ARISE study, available in the public domain, before the completion of recruitment into the study. This will minimise analytical bias and

COSMIC-RAY AND X-RAY HEATING OF INTERSTELLAR CLOUDS AND PROTOPLANETARY DISKS

International Nuclear Information System (INIS)

Glassgold, Alfred E.; Galli, Daniele; Padovani, Marco

2012-01-01

Cosmic-ray and X-ray heating are derived from the electron energy-loss calculations of Dalgarno, Yan, and Liu for hydrogen-helium gas mixtures. These authors treated the heating from elastic scattering and collisional de-excitation of rotationally excited hydrogen molecules. Here we consider the heating that can arise from all ionization and excitation processes, with particular emphasis on the reactions of cosmic-ray and X-ray generated ions with the heavy neutral species, which we refer to as chemical heating. In molecular regions, chemical heating dominates and can account for 50% of the energy expended in the creation of an ion pair. The heating per ion pair ranges in the limit of negligible electron fraction from ∼4.3 eV for diffuse atomic gas to ∼13 eV for the moderately dense regions of molecular clouds and to ∼18 eV for the very dense regions of protoplanetary disks. An important general conclusion of this study is that cosmic-ray and X-ray heating depends on the physical properties of the medium, i.e., on the molecular and electron fractions, the total density of hydrogen nuclei, and, to a lesser extent, on the temperature. It is also noted that chemical heating, the dominant process for cosmic-ray and X-ray heating, plays a role in UV irradiated molecular gas.

Phonon-induced anomalous specific heat of a model nanocrystal by computer simulation

International Nuclear Information System (INIS)

Wang, J.; Wolf, D.; Phillpot, S.R.; Gleiter, H.

1994-10-01

The authors construct a simple model of a nanocrystalline material in which all the grains are the same size and shape, and in which all the grain boundaries are crystallographically identical. The authors show that the model nanocrystal has a low-temperature specific-heat anomaly similar to that seen in experiment, which arises from the presence of low-frequency phonons localized at the grain boundaries

Magnetohydrodynamic flow and heat transfer around a heated cylinder of arbitrary conductivity

Science.gov (United States)

Tassone, A.; Nobili, M.; Caruso, G.

2017-11-01

The interaction of the liquid metal with the plasma confinement magnetic field constitutes a challenge for the design of fusion reactor blankets, due to the arise of MHD effects: increased pressure drops, heat transfer suppression, etc. To overcome these issues, a dielectric fluid can be employed as coolant for the breeding zone. A typical configuration involves pipes transverse to the liquid metal flow direction. This numerical study is conducted to assess the influence of pipe conductivity on the MHD flow and heat transfer. The CFD code ANSYS CFX was employed for this purpose. The fluid is assumed to be bounded by rectangular walls with non-uniform thickness and subject to a skewed magnetic field with the main component aligned with the cylinder axis. The simulations were restricted to Re = (20; 40) and M = (10; 50). Three different scenarios for the obstacle were considered: perfectly insulating, finite conductivity and perfectly conducting. The electrical conductivity was found to affect the channel pressure penalty due to the obstacle insertion only for M = 10 and just for the two limiting cases. A general increment of the heat transfer with M was found due to the tendency of the magnetic field to equalize the flow rate between the sub-channels individuated by the pipe. The best results were obtained with the insulating pipe, due to the reduced electromagnetic drag. The generation of counter-rotating vortices close to the lateral duct walls was observed for M = 50 and perfectly conducting pipe as a result of the modified currents distribution.

Lower Limb Injuries Arising From Motorcycle Crashes | Kortor ...

African Journals Online (AJOL)

Background: Motorcycle accidents are the second most common cause of road traffic accidents in both developing and developed countries. In this study we aim to look at the pattern and characteristics of lower limb injuries arising from motorcycle accidents and evaluate early outcome of treatment. Methods: All the patients ...

On time-dependent diffusion coefficients arising from stochastic processes with memory

Science.gov (United States)

Carpio-Bernido, M. Victoria; Barredo, Wilson I.; Bernido, Christopher C.

2017-08-01

Time-dependent diffusion coefficients arise from anomalous diffusion encountered in many physical systems such as protein transport in cells. We compare these coefficients with those arising from analysis of stochastic processes with memory that go beyond fractional Brownian motion. Facilitated by the Hida white noise functional integral approach, diffusion propagators or probability density functions (pdf) are obtained and shown to be solutions of modified diffusion equations with time-dependent diffusion coefficients. This should be useful in the study of complex transport processes.

On a mechanism of antenna phasing effect on impurity production during ICRF plasma heating

International Nuclear Information System (INIS)

Chechkin, V.V.; Grigor'eva, L.I.

1990-01-01

An appreciable reduction of the metal impurity in flux and a decrease in SOL plasma parameter disturbance occure during ICRP heating in some tokamaks when toroidally adjacent antennae are driven in anti-phase. Also cancelled are low-frequency electric field fluctuations arising in the sheaths and the associated charged particle flux fluctuations. 24 refs.; 7 figs

Squamous cell carcinoma arising in previously burned or irradiated skin

International Nuclear Information System (INIS)

Edwards, M.J.; Hirsch, R.M.; Broadwater, J.R.; Netscher, D.T.; Ames, F.C.

1989-01-01

Squamous cell carcinoma (SCC) arising in previously burned or irradiated skin was reviewed in 66 patients treated between 1944 and 1986. Healing of the initial injury was complicated in 70% of patients. Mean interval from initial injury to diagnosis of SCC was 37 years. The overwhelming majority of patients presented with a chronic intractable ulcer in previously injured skin. The regional relapse rate after surgical excision was very high, 58% of all patients. Predominant patterns of recurrence were in local skin and regional lymph nodes (93% of recurrences). Survival rates at 5, 10, and 20 years were 52%, 34%, and 23%, respectively. Five-year survival rates in previously burned and irradiated patients were not significantly different (53% and 50%, respectively). This review, one of the largest reported series, better defines SCC arising in previously burned or irradiated skin as a locally aggressive disease that is distinct from SCC arising in sunlight-damaged skin. An increased awareness of the significance of chronic ulceration in scar tissue may allow earlier diagnosis. Regional disease control and survival depend on surgical resection of all known disease and may require radical lymph node dissection or amputation

Minimum heat flux (MHF) point in pool and external-flow boiling

International Nuclear Information System (INIS)

Nishio, Shigefumi

1983-01-01

As for the boiling phenomena near a minimum heat flux (MHF) point to which attention has been paid recently concerning the safety analysis of LWR cores, the results of research have not been put in order sufficiently. Therefore in this explanation, the object is limited to pool boiling and external flow boiling, and it is attempted to rearrange the present knowledge on the phenomena near a MHF point from the viewpoint of the relation to the state of solid-liquid contact, the effect of various factors on a MHF point and the modeling of a MHF point. The heat transfer characteristics in boiling phenomena are represented by a curve with one maximum and one minimum points. The MHF point is called also minimum film boiling point. In a heat flux-controlled heating surface, temperature jump arises when heat flux is decreased at a MHF point. The phenomena near a MHF point and the technological background when a MHF point becomes a problem are explained. Near a MHF point, only partial, intermittent solid-liquid contact is maintained. The effects of solid-liquid contact mode, the geometry of a heating surface, pressure and others on a MHF point are discussed. (Kako, I.)

Solitary osteochondroma arising in lumbar spinous process: Case report

Directory of Open Access Journals (Sweden)

Khaled Hadhri

2016-12-01

Full Text Available Solitary osteochondromas rarely occur in the axial skeleton. Those tumors mostly arise on the posterior elements of the cervical column causing various symptoms especially when developing within the spinal canal. Exophytic lumbar variety is uncommon presenting with palpable mass or spinal deformity. We report a 20-year-old man presenting with a solid painless mass at the lower lumbar region. Radiological examinations revealed an exophytic lesion arising in the third lumbar spinous process appearing to be a solitary osteochondroma. The lesion was treated by en-bloc resection; histopathological examination confirmed the diagnosis of osteochondroma with no evidence of recurrence at the end of 2-year follow up.

On the radiogenic heat production of igneous rocks

Directory of Open Access Journals (Sweden)

D. Hasterok

2017-09-01

Full Text Available Radiogenic heat production is a physical parameter crucial to properly estimating lithospheric temperatures and properly understanding processes related to the thermal evolution of the Earth. Yet heat production is, in general, poorly constrained by direct observation because the key radiogenic elements exist in trace amounts making them difficulty image geophysically. In this study, we advance our knowledge of heat production throughout the lithosphere by analyzing chemical analyses of 108,103 igneous rocks provided by a number of geochemical databases. We produce global estimates of the average and natural range for igneous rocks using common chemical classification systems. Heat production increases as a function of increasing felsic and alkali content with similar values for analogous plutonic and volcanic rocks. The logarithm of median heat production is negatively correlated (r2 = 0.98 to compositionally-based estimates of seismic velocities between 6.0 and 7.4 km s−1, consistent with the vast majority of igneous rock compositions. Compositional variations for continent-wide models are also well-described by a log-linear correlation between heat production and seismic velocity. However, there are differences between the log-linear models for North America and Australia, that are consistent with interpretations from previous studies that suggest above average heat production across much of Australia. Similar log-linear models also perform well within individual geological provinces with ∼1000 samples. This correlation raises the prospect that this empirical method can be used to estimate average heat production and natural variance both laterally and vertically throughout the lithosphere. This correlative relationship occurs despite a direct causal relationship between these two parameters but probably arises from the process of differentiation through melting and crystallization.

Nanoparticles of Sr(OH)2: synthesis in homogeneous phase at low temperature and application for cultural heritage artefacts

International Nuclear Information System (INIS)

Ciliberto, E.; Condorelli, G.G.; La Delfa, S.; Viscuso, E.

2008-01-01

This paper concerns the synthesis and the characterization of nanometer particles of Sr(OH) 2 , a moderately high water soluble hydroxide (Ksp=3.2 x 10 -4 at 25 C). The reported process yields strontium hydroxide nanoparticles starting from low cost raw materials in aqueous medium (homogeneous phase) at low temperature (below 100 C) by chemical precipitation from salt solutions, involving very simple operational steps and avoiding the use of organic solvents. Observations by X-ray diffraction (XRD), scanning electron microscopy (SEM), electron dispersive X-Ray (EDX) and Fourier transform infrared spectroscopy (FTIR) indicate that the particles are well-crystallized and have nanometer dimensions (∝30 nm in diameter). Moreover, experimental evidence shows the potential use of this material for the protection and the consolidation of wall paintings (frescoes), paper, stone, wood and other artistic artefacts. (orig.)

Video manometry of the sphincter of Oddi: a new aid for interpreting manometric tracings and excluding manometric artefacts

DEFF Research Database (Denmark)

Madácsy, L; Middelfart, H V; Matzen, Peter

2000-01-01

was to develop a new method sphincter of Oddi video manometry-based on simultaneous ESOM and real-time endoscopic image analysis, and to investigate the usefulness of video manometry for detecting manometric artefacts during ESOM. PATIENTS AND METHODS: Seven consecutive patients who had undergone cholecystectomy...... and were referred with a suspicion of sphincter of Oddi dysfunction were investigated. Sphincter of Oddi pressure and endoscopic images (20 frames/s) were recorded simultaneously on a Synectics PC Polygraf computer system with a time-correlated basis, and then compared. RESULTS: On ESOM, 69 sphincter......, or retching, were also easily recognized using simultaneous ESOM and real-time endoscopic image analysis. CONCLUSIONS: Video manometry of the sphincter of Oddi is a promising new method for improving the analysis and documentation of ESOM tracings. It has several advantages over the conventional technique...

The artefacts of radiochromic film dosimetry with flatbed scanners and their causation by light scattering from radiation-induced polymers

International Nuclear Information System (INIS)

Schoenfeld, Andreas A; Poppinga, Daniela; Poppe, Bjoern; Harder, Dietrich; Doerner, Karl-Joachim

2014-01-01

Optical experiments and theoretical considerations have been undertaken in order to understand the causes of the ‘orientation effect’ and the ‘parabola effect’, the artefacts impairing the desired light absorption measurement on radiochromic EBT3 films with flatbed scanners. EBT3 films exposed to doses up to 20.9 Gy were scanned with an Epson Expression 10000XL flatbed scanner in landscape and portrait orientation. The horizontally and vertically polarized light components of the scanner were determined, and another Epson Expression 10000XL flatbed scanner was disassembled to examine its optical components. The optical properties of exposed and unexposed EBT3 films were studied with incident polarized and unpolarized white light, and the transmitted red light was investigated for its polarization and scattering properties including the distribution of the scattering angles. Neutral density filters were studied for comparison. Guidance was sought from the theory of light scattering from rod-like macromolecular structures. The drastic dose-dependent variation of the transmitted total light current as function of the orientation of front and rear polarizers, interpreted by light scattering theory, shows that the radiation-induced polymerization of the monomers of EBT3 films produces light scattering oscillators preferably polarized at right angles with the coating direction of the film. The directional distribution of the scattered light is partly anisotropic, with a preferred scattering plane at right angles with the coating direction, indicating light scattering from stacks of coherently vibrating oscillators piled up along the monomer crystals. The polyester carrier film also participates in these effects. The ‘orientation’ and ‘parabola’ artefacts due to flatbed scanning of radiochromic films can be explained by the interaction of the polarization-dependent and anisotropic light scattering from exposed and unexposed EBT3 films with the quantitative

Post-transplant Lymphoproliferative Disorder Arising from Renal Allograft Parenchyma: A Case Report

Energy Technology Data Exchange (ETDEWEB)

Park, Byung Kwan; Kim, Chan Kyo; Kwon, Ghee Young [Samsung Medical Center, Sungkyunkwan University College of Medicine, Seoul (Korea, Republic of)

2010-06-15

Post-transplant lymphoproliferative disorder (PTLD) is a rare but serious complication that occurs in patients undergoing kidney transplantation. PTLD usually manifests as a renal hilar mass comprised of histologically B-lymphocytes. We report our experience of managing a patient with PTLD arising from renal parenchyma. Ultrasonographic and MR imaging features of this unusual PTLD suggested differentiated renal cell carcinoma arising from the renal allograft

Shallow and Deep Latent Heating Modes Over Tropical Oceans Observed with TRMM PR Spectral Latent Heating Data

Science.gov (United States)

Takayabu, Yukari N.; Shige, Shoichi; Tao, Wei-Kuo; Hirota, Nagio

2010-01-01

The global hydrological cycle is central to the Earth's climate system, with rainfall and the physics of its formation acting as the key links in the cycle. Two-thirds of global rainfall occurs in the Tropics. Associated with this rainfall is a vast amount of heat, which is known as latent heat. It arises mainly due to the phase change of water vapor condensing into liquid droplets; three-fourths of the total heat energy available to the Earth's atmosphere comes from tropical rainfall. In addition, fresh water provided by tropical rainfall and its variability exerts a large impact upon the structure and motions of the upper ocean layer. Three-dimensional distributions of latent heating estimated from Tropical Rainfall Measuring Mission Precipitation Radar (TRMM PR)utilizing the Spectral Latent Heating (SLH) algorithm are analyzed. Mass-weighted and vertically integrated latent heating averaged over the tropical oceans is estimated as approx.72.6 J/s (approx.2.51 mm/day), and that over tropical land is approx.73.7 J/s (approx.2.55 mm/day), for 30degN-30degS. It is shown that non-drizzle precipitation over tropical and subtropical oceans consists of two dominant modes of rainfall systems, deep systems and congestus. A rough estimate of shallow mode contribution against the total heating is about 46.7 % for the average tropical oceans, which is substantially larger than 23.7 % over tropical land. While cumulus congestus heating linearly correlates with the SST, deep mode is dynamically bounded by large-scale subsidence. It is notable that substantial amount of rain, as large as 2.38 mm day-1 in average, is brought from congestus clouds under the large-scale subsiding circulation. It is also notable that even in the region with SST warmer than 28 oC, large-scale subsidence effectively suppresses the deep convection, remaining the heating by congestus clouds. Our results support that the entrainment of mid-to-lower-tropospheric dry air, which accompanies the large

Heat transfer in vapour-liquid flow of carbon dioxide

International Nuclear Information System (INIS)

Yagov, V.V.

2009-01-01

During the last decade a number of studies of boiling heat transfer in carbon dioxide notably increase. As a field of CO 2 practical using corresponds to high reduced pressures, and a majority of available experimental data on CO 2 flow boiling even in submillimetric channels relate to turbulent liquid flow regimes, a possibility arises to develop sufficiently general method for HTC predicting. Under the above conditions nucleate boiling occurs up to rather high flow quality, even in annular flow regime due to extremely small size of an equilibrium vapour bubble. This conclusion is in agreement with the available experimental data. The predicting equation for nucleate boiling heat transfer developed by the present author in 1988 is valid for any nonmetallic liquid. A contribution of forced convection in heat transfer is calculated according to the Petukhov et al. equation with correction factor, which accounted for an effect of velocity increase due to evaporation. This effect can be essential at relatively small heat fluxes and rather high mass flow rates. The Reynolds analogy and homogeneous model are used in order to account for the convective heat transfer augmentation in two-phase flow. Due to low ratio of liquid and vapour densities at high reduced pressures the homogeneous approximation of two-phase flow seems to be warranted. A total heat transfer coefficient is calculated as an interpolated value of boiling and convective HTCs. The experimental data on CO 2 flow boiling related to regimes before heated wall dryout incipience are in rather good agreement with the calculations. (author)

Security risks arising from portable storage devices

CSIR Research Space (South Africa)

Molotsi, K

2012-10-01

Full Text Available of the security risks arising from the use of PSDs, and further provides possible security countermeasures to help organisations and users to protect their digital assets. APPROACH Literature review: ? To investigate security risks posed by PSDs... technology in the workplace. International Journal of Electronic Security and Digital Forensics. 3(1): 73?81 [3] Kim, K., Kim, E. & Hong S. (2009). Privacy information protection in portable device. Proceedings of International Conference on Convergence...

Dual reciprocity boundary element analysis for the laminar forced heat convection problem in concentric annulus

International Nuclear Information System (INIS)

Choi, Chang Yong

1999-01-01

This paper presents a study of the Dual Reciprocity Boundary Element Method (DRBEM) for the laminar heat convection problem in a concentric annulus with constant heat flux boundary condition. DRBEM is one of the most successful technique used to transform the domain integrals arising from the nonhomogeneous term of the poisson equation into equivalent boundary only integrals. This recently developed and highly efficient numerical method is tested for the solution accuracy of the fluid flow and heat transfer study in a concentric annulus. Since their exact solutions are available, DRBEM solutions are verified with different number of boundary element discretization and internal points. The results obtained in this study are discussed with the relative error percentage of velocity and temperature solutions, and potential applicability of the method for the more complicated heat convection problems with arbitrary duct geometries

Heat recovery from wastewater systems; Waermerueckgewinnung aus Abwassersystemen

Energy Technology Data Exchange (ETDEWEB)

Wanner, O.

2004-07-01

Wastewater contains large amounts of heat energy which can be recovered by means of a heat pump and a heat exchanger installed in the sewer system. Practical problems, which may arise and have been investigated in this research project, are the reduction of the heat transfer efficiency due to heat exchanger fouling and the reduction of the nitrification capacity of downstream wastewater treatment plants due to lower wastewater temperatures. A mathematical model was developed by which the decrease of the wastewater temperature in the treatment plant influent can be determined as a function of the amount of heat energy gathered from the wastewater in the sewer system. By this model the variation in time and space of the wastewater temperature in a sewer pipe is calculated for given hydraulics, geometry and environmental conditions. By analysis of data from a large wastewater treatment plant and simulations with a calibrated model, the effect of lowered influent temperatures on nitrification safety, total nitrogen removal efficiency and ammonium effluent concentrations could be quantified. A procedure is suggested by which the reserve nitrification capacity of an existing treatment plant and the increase of the ammonium effluent concentration resulting from a permanent decrease of the wastewater influent temperature can be estimated. By experiments with a pilot scale heat exchanger in a small wastewater channel, the significance of parameters known to have an effect on fouling was investigated and measures to reduce fouling were tested. The measures tested included controlled variation of the wastewater flow velocity (flushing), coatings and finish of the heat exchanger surface and obstacles mounted on the surface. The best results were obtained by regular short term increases of the flow velocity. By this measure, the efficiency of the fouled heat exchanger, which on the average was 60% of the efficiency of the clean heat exchanger, could repeatedly be raised to an

Convex solutions of systems arising from Monge-Ampere equations

Directory of Open Access Journals (Sweden)

Haiyan Wang

2009-10-01

Full Text Available We establish two criteria for the existence of convex solutions to a boundary value problem for weakly coupled systems arising from the Monge-Ampère equations. We shall use fixed point theorems in a cone.

A mixed-integer nonlinear programming approach to the optimal design of heat network in a polygeneration energy system

International Nuclear Information System (INIS)

Zhang, Jianyun; Liu, Pei; Zhou, Zhe; Ma, Linwei; Li, Zheng; Ni, Weidou

2014-01-01

Highlights: • Integration of heat streams with HRSG in a polygeneration system is studied. • A mixed-integer nonlinear programming model is proposed to optimize heat network. • Operating parameters and heat network configuration are optimized simultaneously. • The optimized heat network highly depends on the HRSG type and model specification. - Abstract: A large number of heat flows at various temperature and pressure levels exist in a polygeneration plant which co-produces electricity and chemical products. Integration of these external heat flows in a heat recovery steam generator (HRSG) has great potential to further enhance energy efficiency of such a plant; however, it is a challenging problem arising from the large design space of heat exchanger network. In this paper, a mixed-integer nonlinear programming model is developed for the design optimization of a HRSG with consideration of all alternative matches between the HRSG and external heat flows. This model is applied to four polygeneration cases with different HRSG types, and results indicate that the optimized heat network mainly depends on the HRSG type and the model specification

Present status of heat transfer in narrow gap rectangular channel

International Nuclear Information System (INIS)

Sudo, Yukio; Kaminaga, Masanori

1990-01-01

In the safety evaluation for research nuclear reactors, at the time of abnormal transient change and accidents, after the tripping of a primary coolant pump, such event that the flow direction of coolant in a core reverses from steady downward flow to rising flow is supposed. In this case, the coexisting convection field, in which free convection and forced convection coexist, arises in place of forced convection, and especially in the research reactors using plate type fuel like JRR-3, it is important to grasp the heat transfer characteristics in the coexisting convection field in a narrow channel. Jackson et al. proposed the heat transfer correlation equation which can be applied to wide conditions including the coexisting convection zone, but its applicability to a narrow channel has not been confirmed. Based on the experimental results, in this study, the effect that the decrease of gap exerts to the convection heat transfer characteristics reported so far was investigated. The experiment and the results are reported. In this experiment on the coexisting convection zone in a narrow gap, the effect of main flow acceleration arose sufficiently large as compared with the effect of buoyancy, and heat transfer was promoted. (K.I.)

Effects arising from charged particles overcoming of the light velocity barrier

International Nuclear Information System (INIS)

Afanas'ev, G.N.; Eliseev, S.M.; Stepanovskij, Yu.P.

1997-01-01

The effects arising from accelerated and decelerated motion of the charged point particle inside the medium are studied. It is shown explicitly that in addition to the Bremsstrahlung and Cherenkov shock wave, the electromagnetic shock wave arising from the charge overcoming the light velocity in the medium should be observed. This shock wave has the same singularity as the Cherenkov one and, therefore, it is more singular than the Bremsstrahlung shock wave. The space-time regions where these shock waves exist and conditions under which they appear are determined

Adenocarcinomas arising from primary retroperitoneal mature teratomas: CT and MR imaging

International Nuclear Information System (INIS)

Wang, Li-Jen; Wong, Yon-Cheong; Chu, Sheng-Hsien; Ng, Kwai-Fong

2002-01-01

An adenocarcinoma arising from mature teratoma is one form of teratoma with malignant transformation. It is extremely rare but highly malignant. The authors report two patients with adenocarcinomas arising from primary retroperitoneal teratomas. The CT and MRI findings of the tumors are presented with emphasis on imaging features implying the presence of malignant transformation and differing from those of pure benign mature teratoma. Correct diagnosis of the presence of malignant transformation from a benign mature teratoma can be made as early as possible by awareness of the imaging features. (orig.)

Ecknomic benefits arising from the Canadian nuclear industry

International Nuclear Information System (INIS)

1982-03-01

This document is a collection of surveys of the Canadian nuclear industry, with forecasts covering a number of possible scenarios. Topics covered include uranium mining and processing; economic benefits arising from the design, manufacture and construction of CANDU generating stations; employment and economic activity in the Canadian nqclear industry; and an overview of the remainder of the industry

High temperature heat exchanger application in power engineering and energy-technological processes

International Nuclear Information System (INIS)

Shpilrain, E.E.

1986-01-01

The possibilities for intensification of various processes in metallurgy and chemical technology, the prospects for enhancing power plant efficiency are often linked with temperature increase of reagents, heat carriers and working fluids. In some cases elevated temperatures give the opportunity to use new and principally different technologies, enhance capacities of power production units and technological apparatuses, improve their economical performance. The variety of problems where high temperature heat exchangers are or can be used are extremely wide. It is therefore impossible to overview all of them in one lecture. Therefore the author tries to consider only some examples which are typical and gives an impression of what kind of problems arise in these cases

Thermal transfer and apparent-dose distributions in poorly bleached mortar samples: Results from single grains and small aliquots of quartz

DEFF Research Database (Denmark)

Jain, M.; Thomsen, Kristina Jørkov; Bøtter-Jensen, L.

2004-01-01

In the assessment of doses received from a nuclear accident, considerable attention has been paid to retrospective dosimetry using the optically stimulated luminescence (OSL) of heated materials such as bricks and tiles. Quartz extracted from these artefacts was heated during manufacture;, this p......In the assessment of doses received from a nuclear accident, considerable attention has been paid to retrospective dosimetry using the optically stimulated luminescence (OSL) of heated materials such as bricks and tiles. Quartz extracted from these artefacts was heated during manufacture......;, this process releases all the prior trapped charge and simultaneously sensitises the quartz. Unfortunately unheated materials such as mortar and concrete are more common in industrial sites and particularly in nuclear installations. These materials are usually exposed to daylight during quarrying...... dosimetry. The challenge in using such materials as retrospective dosemeters, is in identifying these well-bleached grains when an accident dose has been superimposed on the original dose distribution. We investigate here, using OSL, the background dose in three different mortar samples: render, whitewash...

Extended use of electronic health records by primary care physicians: Does the electronic health record artefact matter?

Science.gov (United States)

Raymond, Louis; Paré, Guy; Marchand, Marie

2017-04-01

The deployment of electronic health record systems is deemed to play a decisive role in the transformations currently being implemented in primary care medical practices. This study aims to characterize electronic health record systems from the perspective of family physicians. To achieve this goal, we conducted a survey of physicians practising in private clinics located in Quebec, Canada. We used valid responses from 331 respondents who were found to be representative of the larger population. Data provided by the physicians using the top three electronic health record software products were analysed in order to obtain statistically adequate sub-sample sizes. Significant differences were observed among the three products with regard to their functional capability. The extent to which each of the electronic health record functionalities are used by physicians also varied significantly. Our results confirm that the electronic health record artefact 'does matter', its clinical functionalities explaining why certain physicians make more extended use of their system than others.

Transoral videolaryngoscopic surgery for papillary carcinoma arising in lingual thyroid.

Science.gov (United States)

Mogi, Chisato; Shinomiya, Hirotaka; Fujii, Natsumi; Tsuruta, Tomoyuki; Morita, Naruhiko; Furukawa, Tatsuya; Teshima, Masanori; Kanzawa, Maki; Hirokawa, Mitsuyoshi; Otsuki, Naoki; Nibu, Ken-Ichi

2018-05-15

Carcinoma arising in lingual thyroid is an extremely rare entity accounting for only 1% of all reported ectopic thyroids. Here, we report a case of carcinoma arising in lingual thyroid, which has been successfully managed by transoral resection and bilateral neck dissections. A lingual mass 4-cm in diameter with calcification was incidentally detected by computed tomography at medical check-up. No thyroid tissue was observed in normal position. Ultrasound examination showed bilateral multiple lymphadenopathies. Fine needle aspiration biopsy from lymph node in his right neck was diagnosed as Class III and thyroglobulin level of the specimen was 459ng/ml. Due to the difficulty in performing FNA of the lingual masses, right neck dissection was performed in advance for diagnostic purpose. Pathological examination showed existence of large and small follicular thyroid tissues in several lymph nodes, suggesting lymph node metastasis from thyroid carcinoma. Two months after the initial surgery, video-assisted transoral resection of lingual thyroid with simultaneous left neck dissection was performed. Postoperative course was uneventful. Papillary carcinoma was found in the lingual thyroid and thyroid tissues were also found in left cervical lymph nodes. Video-assisted transoral resection was useful for the treatment of thyroid cancer arising in lingual thyroid. Copyright © 2018 Elsevier B.V. All rights reserved.

Mucinous adenocarcinoma arising at the anastomotic site after operation for hirschsprung's disease: case report

International Nuclear Information System (INIS)

Kim, Hyung Soo; Yoon, Kwon Ha

2004-01-01

To our knowledge, rectal cancer arising at the anastomotic site after surgery for Hirschsprung's disease has not been reported. We report a case of mucinous adenocarcinoma arising at the anastomotic site after Soave operation 26 years ago

Convective and Stratiform Precipitation Processes and their Relationship to Latent Heating

Science.gov (United States)

Tao, Wei-Kuo; Lang, Steve; Zeng, Xiping; Shige, Shoichi; Takayabu, Yukari

2009-01-01

The global hydrological cycle is central to the Earth's climate system, with rainfall and the physics of its formation acting as the key links in the cycle. Two-thirds of global rainfall occurs in the Tropics. Associated with this rainfall is a vast amount of heat, which is known as latent heat. It arises mainly due to the phase change of water vapor condensing into liquid droplets; three-fourths of the total heat energy available to the Earth's atmosphere comes from tropical rainfall. In addition, fresh water provided by tropical rainfall and its variability exerts a large impact upon the structure and motions of the upper ocean layer. An improved convective -stratiform heating (CSH) algorithm has been developed to obtain the 3D structure of cloud heating over the Tropics based on two sources of information: 1) rainfall information, namely its amount and the fraction due to light rain intensity, observed directly from the Precipitation Radar (PR) on board the TRMM satellite and 2) synthetic cloud physics information obtained from cloud-resolving model (CRM) simulations of cloud systems. The cloud simulations provide details on cloud processes, specifically latent heating, eddy heat flux convergence and radiative heating/cooling, that. are not directly observable by satellite. The new CSH algorithm-derived heating has a noticeably different heating structure over both ocean and land regions compared to the previous CSH algorithm. One of the major differences between new and old algorithms is that the level of maximum cloud heating occurs 1 to 1.5 km lower in the atmosphere in the new algorithm. This can effect the structure of the implied air currents associated with the general circulation of the atmosphere in the Tropics. The new CSH algorithm will be used provide retrieved heating data to other heating algorithms to supplement their performance.

Radiologic findings of malignant tumors arising from ovarian endometriosis

International Nuclear Information System (INIS)

Lee, Eun Ju; Joo, Hee Jae; Kim, Bo Hyun

1999-01-01

To determine the radiologic characteristics of malignant tumors arising from ovarian endometriosis. The radiologic findings of eleven patients with pelvic masses histologically confirmed as malignant ovarian tumors arising from endometriosis were retrospectively reviewed. All patients underwent MR, and six underwent ultrasonography. The findings were evaluated with regard to tumor size and shape, locularity, thickness and enhancement of the wall and septa, the presence of papillary nodule or solid portion, signal intensity of the locule, the presence of mass in contralateral ovary, ascites, local invasion, distant metastases, and the Pathologic diagnosis included clear cell carcinoma in six cases, endometrioid carcinoma in three, and mucinous cystadenocarcinoma of borderline malignancy and endometrial stromal sarcoma in one case each. Tumor size ranged from 8 to 20 (mean, 12.7)cm. The tumors were mixed in four cases, entirely cystic in three, predominantly cystic in three, and predominantly solid in one. Six cases were unilocular and five were multilocular. The wall and septa varied in thickness and regularity and were well enhanced in all but one case. In all cases papillary nodules or solid portions with similar enhancement to uterine myometrium were seen. On T1WI, the signal intensity of fluid was seen to be high in eight cases, low or intermediate in two, and of differing intensity in one. Ten cases showed high signal intensity on T2WI, whereas in one case in which high signal intensity was seen on T1WI, there was low signal intensity(shading). In three cases the contralateral ovary contained an endometrioma. Other features included ascites in seven cases and peritoneal seeding in one. Malignant ovarian tumors arising from endometriosis showed radiologic features of malignancy:they were larger than 10cm, there was enhancement of the wall and septa, and a papillary nodule or solid portion was present. However, the presence of hyperintense fluid, as seen on T1WI

Radiologic findings of malignant tumors arising from ovarian endometriosis

Energy Technology Data Exchange (ETDEWEB)

Lee, Eun Ju; Joo, Hee Jae [Ajou Univ. College of Medicine, Suwon (Korea, Republic of); Kim, Bo Hyun [SungkyunKwan Univ. College of Medicine, Seoul (Korea, Republic of)

1999-11-01

To determine the radiologic characteristics of malignant tumors arising from ovarian endometriosis. The radiologic findings of eleven patients with pelvic masses histologically confirmed as malignant ovarian tumors arising from endometriosis were retrospectively reviewed. All patients underwent MR, and six underwent ultrasonography. The findings were evaluated with regard to tumor size and shape, locularity, thickness and enhancement of the wall and septa, the presence of papillary nodule or solid portion, signal intensity of the locule, the presence of mass in contralateral ovary, ascites, local invasion, distant metastases, and the Pathologic diagnosis included clear cell carcinoma in six cases, endometrioid carcinoma in three, and mucinous cystadenocarcinoma of borderline malignancy and endometrial stromal sarcoma in one case each. Tumor size ranged from 8 to 20 (mean, 12.7)cm. The tumors were mixed in four cases, entirely cystic in three, predominantly cystic in three, and predominantly solid in one. Six cases were unilocular and five were multilocular. The wall and septa varied in thickness and regularity and were well enhanced in all but one case. In all cases papillary nodules or solid portions with similar enhancement to uterine myometrium were seen. On T1WI, the signal intensity of fluid was seen to be high in eight cases, low or intermediate in two, and of differing intensity in one. Ten cases showed high signal intensity on T2WI, whereas in one case in which high signal intensity was seen on T1WI, there was low signal intensity(shading). In three cases the contralateral ovary contained an endometrioma. Other features included ascites in seven cases and peritoneal seeding in one. Malignant ovarian tumors arising from endometriosis showed radiologic features of malignancy:they were larger than 10cm, there was enhancement of the wall and septa, and a papillary nodule or solid portion was present. However, the presence of hyperintense fluid, as seen on T1WI

Heat damage and in vitro starch digestibility of puffed wheat kernels.

Science.gov (United States)

Cattaneo, Stefano; Hidalgo, Alyssa; Masotti, Fabio; Stuknytė, Milda; Brandolini, Andrea; De Noni, Ivano

2015-12-01

The effect of processing conditions on heat damage, starch digestibility, release of advanced glycation end products (AGEs) and antioxidant capacity of puffed cereals was studied. The determination of several markers arising from Maillard reaction proved pyrraline (PYR) and hydroxymethylfurfural (HMF) as the most reliable indices of heat load applied during puffing. The considerable heat load was evidenced by the high levels of both PYR (57.6-153.4 mg kg(-1) dry matter) and HMF (13-51.2 mg kg(-1) dry matter). For cost and simplicity, HMF looked like the most appropriate index in puffed cereals. Puffing influenced starch in vitro digestibility, being most of the starch (81-93%) hydrolyzed to maltotriose, maltose and glucose whereas only limited amounts of AGEs were released. The relevant antioxidant capacity revealed by digested puffed kernels can be ascribed to both the new formed Maillard reaction products and the conditions adopted during in vitro digestion. Copyright © 2015 Elsevier Ltd. All rights reserved.

Hydrogen bonds and heat diffusion in α-helices: a computational study.

Science.gov (United States)

Miño, German; Barriga, Raul; Gutierrez, Gonzalo

2014-08-28

Recent evidence has shown a correlation between the heat diffusion pathways and the known allosteric communication pathways in proteins. Allosteric communication in proteins is a central, yet unsolved, problem in biochemistry, and the study and characterization of the structural determinants that mediate energy transfer among different parts of proteins is of major importance. In this work, we characterized the role of hydrogen bonds in diffusivity of thermal energy for two sets of α-helices with different abilities to form hydrogen bonds. These hydrogen bonds can be a constitutive part of the α-helices or can arise from the lateral chains. In our in vacuo simulations, it was observed that α-helices with a higher possibility of forming hydrogen bonds also had higher rates of thermalization. Our simulations also revealed that heat readily flowed through atoms involved in hydrogen bonds. As a general conclusion, according to our simulations, hydrogen bonds fulfilled an important role in heat diffusion in structural patters of proteins.

The heat kernel as the pagerank of a graph

Science.gov (United States)

Chung, Fan

2007-01-01

The concept of pagerank was first started as a way for determining the ranking of Web pages by Web search engines. Based on relations in interconnected networks, pagerank has become a major tool for addressing fundamental problems arising in general graphs, especially for large information networks with hundreds of thousands of nodes. A notable notion of pagerank, introduced by Brin and Page and denoted by PageRank, is based on random walks as a geometric sum. In this paper, we consider a notion of pagerank that is based on the (discrete) heat kernel and can be expressed as an exponential sum of random walks. The heat kernel satisfies the heat equation and can be used to analyze many useful properties of random walks in a graph. A local Cheeger inequality is established, which implies that, by focusing on cuts determined by linear orderings of vertices using the heat kernel pageranks, the resulting partition is within a quadratic factor of the optimum. This is true, even if we restrict the volume of the small part separated by the cut to be close to some specified target value. This leads to a graph partitioning algorithm for which the running time is proportional to the size of the targeted volume (instead of the size of the whole graph).

Final storage of radioactive waste in Germany. Waste arisings and availability of a repository as seen by an electricity utility

International Nuclear Information System (INIS)

Broeskamp, H.; Brammer, K.J.; Graf, R.

2004-01-01

The management of waste arising in the operation of nuclear power plants has been taken into account since the beginnings of the peaceful uses of nuclear power in Germany. As early as in 1957, a memorandum of the German Advisory Committee on Atomic Energy contains a reference to the need for safe disposal of radioactive waste. Legislation adopted the suggestion and laid down some provisions on the safe utilization of radioactive materials as early as in the Atomic Energy Act of December 23, 1959. In connection with the nuclear waste management center, the Federal Republic also looked for a suitable site for a repository. After thorough site selection proceedings by the federal government and the state of Lower Saxony, the Lower Saxony state government in 1977 defined Gorleben as the site. The decision has been preceded by a three-stage selection process in which more than 140 sites had been investigated. Exploration of the Gorleben site began in 1979 and was interrupted on October 1, 2000 to clarify conceptual and safety-related doubts of the federal government. The German Federal Ministry for the Environment (BMU) seeks to make a repository (for high-level waste) available in 2030. Technically, it is still possible to commission a repository for waste generating heat at Gorleben after 2025 if the salt dome is found to be suitable after speedy conclusion of the exploration work. Reference is made to foreseeable problem areas. Another project pursued by the federal government is the use of the Konrad mine as a repository for low and medium-level radioactive waste. After well over twenty years, the plans approval decision was made in May 2002 and is at present the subject of litigation. On the basis of the data presented about the expected arisings of waste generating no heat in combination with the possible start of emplacement in Konrad in 2013, detailed results are presented. (orig.) [de

Spinal cord injury arising in anaesthesia practice.

Science.gov (United States)

Hewson, D W; Bedforth, N M; Hardman, J G

2018-01-01

Spinal cord injury arising during anaesthetic practice is a rare event, but one that carries a significant burden in terms of morbidity and mortality. In this article, we will review the pathophysiology of spinal cord injury. We will then discuss injuries relating to patient position, spinal cord hypoperfusion and neuraxial techniques. The most serious causes of spinal cord injury - vertebral canal haematoma, spinal epidural abscess, meningitis and adhesive arachnoiditis - will be discussed in turn. For each condition, we draw attention to practical, evidence-based measures clinicians can undertake to reduce their incidence, or mitigate their severity. Finally, we will discuss transient neurological symptoms. Some cases of spinal cord injury during anaesthesia can be ascribed to anaesthesia itself, arising as a direct consequence of its conduct. The injury to a spinal nerve root by inaccurate and/or incautious needling during spinal anaesthesia is an obvious example. But in many cases, spinal cord injury during anaesthesia is not caused by, related to, or even associated with, the conduct of the anaesthetic. Surgical factors, whether direct (e.g. spinal nerve root damage due to incorrect pedicle screw placement) or indirect (e.g. cord ischaemia following aortic surgery) are responsible for a significant proportion of spinal cord injuries that occur concurrently with the delivery of regional or general anaesthesia. © 2018 The Association of Anaesthetists of Great Britain and Ireland.

Heat transfer operators associated with quantum operations

International Nuclear Information System (INIS)

Aksak, C; Turgut, S

2011-01-01

Any quantum operation applied on a physical system is performed as a unitary transformation on a larger extended system. If the extension used is a heat bath in thermal equilibrium, the concomitant change in the state of the bath necessarily implies a heat exchange with it. The dependence of the average heat transferred to the bath on the initial state of the system can then be found from the expectation value of a Hermitian operator, which is named as the heat transfer operator (HTO). The purpose of this paper is to investigate the relation between the HTOs and the associated quantum operations. Since any given quantum operation on a system can be realized by different baths and unitaries, many different HTOs are possible for each quantum operation. On the other hand, there are also strong restrictions on the HTOs which arise from the unitarity of the transformations. The most important of these is the Landauer erasure principle. This paper is concerned with the question of finding a complete set of restrictions on the HTOs that are associated with a given quantum operation. An answer to this question has been found only for a subset of quantum operations. For erasure operations, these characterizations are equivalent to the generalized Landauer erasure principle. For the case of generic quantum operations, however, it appears that the HTOs obey further restrictions which cannot be obtained from the entropic restrictions of the generalized Landauer erasure principle.

Centrifugal Compressor Unit-based Heat Energy Recovery at Compressor Stations

Directory of Open Access Journals (Sweden)

V. S. Shadrin

2016-01-01

Full Text Available About 95% of the electricity consumed by air compressor stations around the world, is transformed into thermal energy, which is making its considerable contribution to global warming. The present article dwells on the re-use (recovery of energy expended for air compression.The article presents the energy analysis of the process of compressing air from the point of view of compressor drive energy conversion into heat energy. The temperature level of excess heat energy has been estimated in terms of a potential to find the ways of recovery of generated heat. It is shown that the temperature level formed by thermal energy depends on the degree of air compression and the number of stages of the compressor.Analysis of technical characteristics of modern equipment from leading manufacturers, as well as projects of the latest air compressor stations have shown that there are two directions for the recovery of heat energy arising from the air compression: Resolving technological problems of compressor units. The use of the excess heat generation to meet the technology objectives of the enterprise. This article examines the schematic diagrams of compressor units to implement the idea of heat recovery compression to solve technological problems: Heating of the air in the suction line during operation of the compressor station in winter conditions. Using compression heat to regenerate the adsorbent in the dryer of compressed air.The article gives an equity assessment of considered solutions in the total amount of heat energy of compressor station. Presented in the present work, the analysis aims to outline the main vectors of technological solutions that reduce negative impacts of heat generation of compressor stations on the environment and creating the potential for reuse of energy, i.e. its recovery.

Kapteyn series arising in radiation problems

International Nuclear Information System (INIS)

Lerche, I; Tautz, R C

2008-01-01

In discussing radiation from multiple point charges or magnetic dipoles, moving in circles or ellipses, a variety of Kapteyn series of the second kind arises. Some of the series have been known in closed form for a hundred years or more, others appear not to be available to analytic persuasion. This paper shows how 12 such generic series can be developed to produce either closed analytic expressions or integrals that are not analytically tractable. In addition, the method presented here may be of benefit when one has other Kapteyn series of the second kind to consider, thereby providing an additional reason to consider such series anew

Solitary osteochondroma arising in lumbar spinous process: Case report.

Science.gov (United States)

Hadhri, Khaled; Tebourbi, Anis; Saidi, Mehdi; Kooli, Mondher

2016-12-01

Solitary osteochondromas rarely occur in the axial skeleton. Those tumors mostly arise on the posterior elements of the cervical column causing various symptoms especially when developing within the spinal canal. Exophytic lumbar variety is uncommon presenting with palpable mass or spinal deformity. We report a 20-year-old man presenting with a solid painless mass at the lower lumbar region. Radiological examinations revealed an exophytic lesion arising in the third lumbar spinous process appearing to be a solitary osteochondroma. The lesion was treated by en-bloc resection; histopathological examination confirmed the diagnosis of osteochondroma with no evidence of recurrence at the end of 2-year follow up. Copyright © 2016 Turkish Association of Orthopaedics and Traumatology. Production and hosting by Elsevier B.V. All rights reserved.

Modelling of large-scale structures arising under developed turbulent convection in a horizontal fluid layer (with application to the problem of tropical cyclone origination

Directory of Open Access Journals (Sweden)

G. V. Levina

2000-01-01

Full Text Available The work is concerned with the results of theoretical and laboratory modelling the processes of the large-scale structure generation under turbulent convection in the rotating-plane horizontal layer of an incompressible fluid with unstable stratification. The theoretical model describes three alternative ways of creating unstable stratification: a layer heating from below, a volumetric heating of a fluid with internal heat sources and combination of both factors. The analysis of the model equations show that under conditions of high intensity of the small-scale convection and low level of heat loss through the horizontal layer boundaries a long wave instability may arise. The condition for the existence of an instability and criterion identifying the threshold of its initiation have been determined. The principle of action of the discovered instability mechanism has been described. Theoretical predictions have been verified by a series of experiments on a laboratory model. The horizontal dimensions of the experimentally-obtained long-lived vortices are 4÷6 times larger than the thickness of the fluid layer. This work presents a description of the laboratory setup and experimental procedure. From the geophysical viewpoint the examined mechanism of the long wave instability is supposed to be adequate to allow a description of the initial step in the evolution of such large-scale vortices as tropical cyclones - a transition form the small-scale cumulus clouds to the state of the atmosphere involving cloud clusters (the stage of initial tropical perturbation.

Design and System Analysis of Quad-Generation Plant Based on Biomass Gasification Integrated with District Heating

DEFF Research Database (Denmark)

Rudra, Souman

alternative by upgrading existing district heating plant. It provides a generic modeling framework to design flexible energy system in near future. These frameworks address the three main issues arising in the planning and designing of energy system: a) socio impact at both planning and proses design level; b...... in this study. The overall aim of this work is to provide a complete assessment of the technical potential of biomass gasification for local heat and power supply in Denmark and replace of natural gas for the production. This study also finds and defines the future areas of research in the gasification......, it possible to lay a foundation for future gasification based power sector to produce flexible output such as electricity, heat, chemicals or bio-fuels by improving energy system of existing DHP(district heating plant) integrating gasification technology. The present study investigate energy system...

Myoepithelial carcinoma arising within an adenomyoepithelioma of the breast: A case report

Energy Technology Data Exchange (ETDEWEB)

Kim, You Yeon; Cho, Kyu Ran; Song, Sung Eun [Dept. of Radiology, Anam Hospital, Korea University College of Medicine, Seoul (Korea, Republic of); Seo, Bo Kyoung [Dept. of Radiology, Ansan Hospital, Korea University College of Medicine, Ansan (Korea, Republic of); Woo, Ok Hee [Dept. of Radiology, Guro Hospital, Korea University College of Medicine, Seoul (Korea, Republic of); Lee, Jeong Hyun [Dept. of Radiology, Anam Hospital, Korea University College of Medicine, Seoul (Korea, Republic of)

2017-07-15

Adenomyoepithelioma of the breast is a rare tumor. A myoepithelial carcinoma arising within an adenomyoepithelioma is even more unusual. There are a limited number of reports discussing myoepithelial carcinoma; most of them describe pathological findings, but not imaging findings. We present a case of a 55-year-old woman who had a screen-detected myoepithelial carcinoma arising within an adenomyoepithelioma in her right breast. Upon the completion of a mammography and sonography an oval shaped mass with an indistinct margin in the upper portion of the right breast had been seen. It as appeared to be a spiculated, irregular-shaped, peripheral-enhancing mass on an MRI. On sonography-guided biopsy, an epithelial-myothelial tumor was confirmed, and the possibility of myoepithelial carcinoma was suggested. Breast-conserving surgery with a sentinel lymph node dissection was performed, and a pathological examination revealed a myoepithelial carcinoma arising within an adenomyoepithelioma.

Point, surface and volumetric heat sources in the thermal modelling of selective laser melting

Science.gov (United States)

Yang, Yabin; Ayas, Can

2017-10-01

Selective laser melting (SLM) is a powder based additive manufacturing technique suitable for producing high precision metal parts. However, distortions and residual stresses within products arise during SLM because of the high temperature gradients created by the laser heating. Residual stresses limit the load resistance of the product and may even lead to fracture during the built process. It is therefore of paramount importance to predict the level of part distortion and residual stress as a function of SLM process parameters which requires a reliable thermal modelling of the SLM process. Consequently, a key question arises which is how to describe the laser source appropriately. Reasonable simplification of the laser representation is crucial for the computational efficiency of the thermal model of the SLM process. In this paper, first a semi-analytical thermal modelling approach is described. Subsequently, the laser heating is modelled using point, surface and volumetric sources, in order to compare the influence of different laser source geometries on the thermal history prediction of the thermal model. The present work provides guidelines on appropriate representation of the laser source in the thermal modelling of the SLM process.

Coupled heat and groundwater flow in porous rock

International Nuclear Information System (INIS)

Rae, J.; Robinson, P.C.; Wickens, L.M.

1983-01-01

There are a number of technical areas where coupled heat and flow problems occur for water in porous rock. The area of most interest to the authors has been the possible disposal underground of high-level radioactive waste. High-level waste can emit enough heat to drive significant flows by buoyancy effects and groundwater flow is expected to be the chief transport process for solute leached from such a repository. The possible disposal of radioactive waste under the seabed raises many similar questions and needs similar techniques to find answers. Other areas where related questions arise are the storage and retrieval of hot water in underground reservoirs, the attempts to extract useful geothermal energy by pumping water into fracture systems in hot rock and in certain thermal techniques for persuading oil to flow in tight reservoirs. The authors address questions in a rather general way and give examples which lie more in the area of waste disposal

Nanoparticles of Sr(OH){sub 2}: synthesis in homogeneous phase at low temperature and application for cultural heritage artefacts

Energy Technology Data Exchange (ETDEWEB)

Ciliberto, E.; Condorelli, G.G.; La Delfa, S.; Viscuso, E. [Universita di Catania, Dipartimento di Scienze Chimiche, Catania (Italy)

2008-07-15

This paper concerns the synthesis and the characterization of nanometer particles of Sr(OH){sub 2}, a moderately high water soluble hydroxide (Ksp=3.2 x 10{sup -4} at 25 C). The reported process yields strontium hydroxide nanoparticles starting from low cost raw materials in aqueous medium (homogeneous phase) at low temperature (below 100 C) by chemical precipitation from salt solutions, involving very simple operational steps and avoiding the use of organic solvents. Observations by X-ray diffraction (XRD), scanning electron microscopy (SEM), electron dispersive X-Ray (EDX) and Fourier transform infrared spectroscopy (FTIR) indicate that the particles are well-crystallized and have nanometer dimensions ({proportional_to}30 nm in diameter). Moreover, experimental evidence shows the potential use of this material for the protection and the consolidation of wall paintings (frescoes), paper, stone, wood and other artistic artefacts. (orig.)

Poorly Differentiated Squamous Cell Carcinoma Arising in Tattooed Skin

Science.gov (United States)

Sarma, Deba P.; Dentlinger, Renee B.; Forystek, Amanda M.; Stevens, Todd; Huerter, Christopher

2010-01-01

Introduction. Tattoos have increasingly become accepted by mainstream Western society. As a result, the incidence of tattoo-associated dermatoses is on the rise. The presence of a poorly differentiated squamous cell carcinoma in an old tattooed skin is of interest as it has not been previously documented. Case Presentation. A 79-year-old white homeless man of European descent presented to the dermatology clinic with a painless raised nodule on his left forearm arising in a tattooed area. A biopsy of the lesion revealed a poorly differentiated squamous cell carcinoma infiltrating into a tattoo. The lesion was completely excised and the patient remains disease-free one year later. Conclusion. All previous reports of squamous cell carcinomas arising in tattoos have been well-differentiated low-grade type or keratoacanthoma-type and are considered to be coincidental rather than related to any carcinogenic effect of the tattoo pigments. Tattoo-associated poorly differentiated invasive carcinoma appears to be extremely rare. PMID:21274289

Poorly Differentiated Squamous Cell Carcinoma Arising in Tattooed Skin

Directory of Open Access Journals (Sweden)

Deba P. Sarma

2010-01-01

Full Text Available Introduction. Tattoos have increasingly become accepted by mainstream Western society. As a result, the incidence of tattoo-associated dermatoses is on the rise. The presence of a poorly differentiated squamous cell carcinoma in an old tattooed skin is of interest as it has not been previously documented. Case Presentation. A 79-year-old white homeless man of European descent presented to the dermatology clinic with a painless raised nodule on his left forearm arising in a tattooed area. A biopsy of the lesion revealed a poorly differentiated squamous cell carcinoma infiltrating into a tattoo. The lesion was completely excised and the patient remains disease-free one year later. Conclusion. All previous reports of squamous cell carcinomas arising in tattoos have been well-differentiated low-grade type or keratoacanthoma-type and are considered to be coincidental rather than related to any carcinogenic effect of the tattoo pigments. Tattoo-associated poorly differentiated invasive carcinoma appears to be extremely rare.

Basal Cell Carcinoma Arising in a Breast Augmentation Scar.

Science.gov (United States)

Edwards, Lisa R; Cresce, Nicole D; Russell, Mark A

2017-04-01

We report a case of a 46-year-old female who presented with a persistent lesion on the inferior right breast. The lesion was located within the scar from a breast augmentation procedure 12 years ago. The lesion had been treated as several conditions with no improvement. Biopsy revealed a superficial and nodular basal cell carcinoma, and the lesion was successfully removed with Mohs micrographic surgery. Basal cell carcinoma arising in a surgical scar is exceedingly rare with only 13 reported cases to date. This is the first reported case of basal cell carcinoma arising in a breast augmentation scar. We emphasize the importance of biopsy for suspicious lesions or those refractory to treatment, particularly those lesions that form within a scar. Level of Evidence V This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Low temperature specific heat of Lu-Cu-Y metallic glasses

Energy Technology Data Exchange (ETDEWEB)

Mohammed, K.A.; Lanchester, P.C.

1987-02-01

The specific heat of a series of amorphous metallic alloys of the form Lu/sub x/Cu/sub 0.37/Y/sub 0.36/ (x=0, 0.1, 0.3 and 0.4) has been measured between 2 and 50 K, primarily in order to be able to determine the non-magnetic contributions to the specific heat in magnetic Re-Cu-Y amorphous alloys. The data at low temperature fit the simple form C/sub p/=..gamma..T+..beta..T/sup 3/ from which values of ..gamma.. and theta/sub D/(0) have been determined. Consideration is given to the error that arises if Y is used rather than Lu or La in forming non-magnetic rare earth intermetallics for purposes of determining the non-magnetic contributions to the specific heat of magnetic samples. A simple procedure is described that allows a useful improvement in accuracy in estimating non-magnetic contributions below 20 K if Y is used. The method may also be useful if only a restricted range of compositions using Lu is possible.

Heat-flow patterns in Tian-Calvet microcalorimeters: Conductive, convective, and radiative transport in gas dosing experiments

International Nuclear Information System (INIS)

Vilchiz, Luis Enrique; Pacheco-Vega, Arturo; Handy, Brent E.

2005-01-01

Mathematical models of a Tian-Calvet microcalorimeter were solved numerically by the finite-element method in an effort to understand the relative importance of the three basic heat transfer mechanisms operative during gas dosing experiments typically used to determine heats of adsorption on catalysts and adsorbents. The analysis pays particular attention to the quantitative release of heat through various elements of the cell and sensor cups to assess time delays and the deg.ree of thermal shunting that may result in inaccuracies in calorimetric measurements. Conductive transfer predominates in situations where there is high gas headspace pressure. The convection currents that arise when dosing with considerable gas pressure in the cell headspace region are not sufficiently strong to shunt significant amounts of sample heat away from being sensed by the surrounding thermopiles. Therefore, the heat capture fraction (heat sensed/heat produced) does not vary significantly with gas headspace pressure. During gas dosing under very low gas headspace pressure, radiation losses from the top of the sample bed may significantly affect the heat capture fraction, leading to underestimations of adsorption heats, unless the heat radiated from the top of the catalyst bed is effectively reflected back to the sample region or absorbed by an inert packing layer also in thermal contact with the thermopile wall

Simulating Arctic clouds during Arctic Radiation- IceBridge Sea and Ice Experiment (ARISE)

Science.gov (United States)

Bromwich, D. H.; Hines, K. M.; Wang, S. H.

2015-12-01

The representation within global and regional models of the extensive low-level cloud cover over polar oceans remains a critical challenge for quantitative studies and forecasts of polar climate. In response, the polar-optimized version of the Weather Research and Forecasting model (Polar WRF) is used to simulate the meteorology, boundary layer, and Arctic clouds during the September-October 2014 Arctic Radiation- IceBridge Sea and Ice Experiment (ARISE) project. Polar WRF was developed with several adjustments to the sea ice thermodynamics in WRF. ARISE was based out of Eielson Air Force Base near Fairbanks, Alaska and included multiple instrumented C-130 aircraft flights over open water and sea ice of the Beaufort Sea. Arctic boundary layer clouds were frequently observed within cold northeasterly flow over the open ocean and ice. Preliminary results indicate these clouds were primarily liquid water, with characteristics differing between open water and sea ice surfaces. Simulated clouds are compared to ARISE observations. Furthermore, Polar WRF simulations are run for the August-September 2008 Arctic Summer Cloud Ocean Study (ASCOS) for comparison to the ARISE. Preliminary analysis shows that simulated low-level water clouds over the sea ice are too extensive during the the second half of the ASCOS field program. Alternatives and improvements to the Polar WRF cloud schemes are considered. The goal is to use the ARISE and ASCOS observations to achieve an improved polar supplement to the WRF code for open water and sea ice that can be provided to the Polar WRF community.

Parallel gradient effects on ICRH (Ion Cyclotron Resonance Heating) in Tokamaks

International Nuclear Information System (INIS)

Smithe, D.N.

1987-01-01

This dissertation examines the effects on Ion Cyclotron Resonance Heating of parallel nonuniformity in the magnetic field which arises from the poloidal field in a tokamak and the universal (major radius)/sup /minus/1/ scaling of the cyclotron frequency. The goal of the analysis is the macroscopic warm plasma current including temperature in the sense of the finite Larmor radius expansion and the quasilocal approximation of the parallel guiding center motion. A 1-D numerical application of the fully nonlocal integral dielectric is performed. Parallel gradient effects are studied for He-3 minority, 2nd harmonic deuterium, and hydrogen minority heating in tokamaks. The results show quite significant alteration of the toroidal wavenumber absorption spectrum, and a wealth of new behavior on the local propagation scale. 95 refs., 37 figs

High grade angiosarcoma arising in fibroadenoma

Science.gov (United States)

2011-01-01

Primary angiosarcoma of the breast is a rare tumour that account for fewer than 0.05% of all malignant mammary tumours. Angiosarcoma may have an perfidious clinical onset. Radiologic findings are often nonspecific and may appear completely normal in one-third of cases with primary angiosarcoma. The prognosis is usually poor because of the high rates of local recurrence and early development of metastases. Aggressive surgical resection is the mainstay of treatment. The role of adjuvant therapy has not yet been well established. Here we present a case of a 53 year old, postmenopausal women with primary angiosarcoma arising in fibroadenoma. To our knowledge, this is the first case described in the literature to date. PMID:22185665

Periorbital nodular fasciitis arising during pregnancy

Directory of Open Access Journals (Sweden)

Brandon N Phillips

2014-01-01

Full Text Available Nodular fasciitis (NF is a benign proliferation of fibroblasts and myofibroblasts that rarely occurs in the periorbital region. We report what we believe to be the first case of periorbital NF associated with pregnancy. A case of intravascular fasciitis, a NF variant, has been reported during pregnancy, but it was not located in the periorbital region. A weak presence of estrogen receptors has been reported in NF. This may make it more susceptible to the hormone-related changes during pregnancy and contribute to the development of the lesion by stimulating fibroblasts and smooth muscle cell types. Although rare, NF should be considered in the differential diagnosis of periorbital soft-tissue masses arising during pregnancy.

Sound radiation quantities arising from a resilient circular radiator

NARCIS (Netherlands)

Aarts, R.M.; Janssen, A.J.E.M.

2009-01-01

Power series expansions in ka are derived for the pressure at the edge of a radiator, the reaction force on the radiator, and the total radiated power arising from a harmonically excited, resilient, flat, circular radiator of radius a in an infinite baffle. The velocity profiles on the radiator are

Performance Investigation of a Handheld 3d Scanner to Define Good Practices for Small Artefact 3d Modeling

Science.gov (United States)

Lachat, E.; Landes, T.; Grussenmeyer, P.

2017-08-01

Handheld 3D scanners can be used to complete large scale models with the acquisition of occluded areas or small artefacts. This may be of interest for digitization projects in the field of Cultural Heritage, where detailed areas may require a specific treatment. Such sensors present the advantage of being easily portable in the field, and easily usable even without particular knowledge. In this paper, the Freestyle3D handheld scanner launched on the market in 2015 by FARO is investigated. Different experiments are described, covering various topics such as the influence of range or color on the measurements, but also the precision achieved for geometrical primitive digitization. These laboratory experiments are completed by acquisitions performed on engraved and sculpted stone blocks. This practical case study is useful to investigate which acquisition protocol seems to be the more adapted and leads to precise results. The produced point clouds will be compared to photogrammetric surveys for the purpose of their accuracy assessment.

Basal Cell Carcinoma Arising in a Tattooed Eyebrow

Science.gov (United States)

Lee, Jong-Sun; Park, Jin; Kim, Seong-Min; Kim, Han-Uk

2009-01-01

Malignant skin tumors, including squamous cell carcinoma and malignant melanoma, have occurred in tattoos. Seven documented cases of basal cell carcinoma associated with tattoos have also been reported in the medical literature. We encountered a patient with basal cell carcinoma in a tattooed eyebrow. We report on this case as the eighth reported case of a patient with basal cell carcinoma arising in a tattooed area. PMID:20523804

Pressurized Hybrid Heat Pipe for Passive IN-Core Cooling System (PINCs) in Advanced Nuclear Power Plants

Energy Technology Data Exchange (ETDEWEB)

Kim, Kyung Mo; Bang, In Cheol [Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of)

2016-05-15

The representative operating limit of the thermosyphon heat pipe is flooding limit that arises from the countercurrent flow of vapor and liquid. The effect of difference between wetted perimeter and heated perimeter on the flooding limit of the thermosyphons has not been studied; despite the effect of cross-sectional area of the vapor path on the heat transfer characteristics of thermosyphons have been studied. Additionally, the hybrid heat pipe must operate at the high temperature and high pressure environment because it will be inserted to the active core to remove the decay heat. However, the previously studied heat pipes operated below the atmospheric pressure. Therefore, the effect of the unique geometry for hybrid heat pipe and operating pressure on the heat transfer characteristics including the flooding limit of hybrid heat pipe was experimentally measured. Hybrid heat pipe as a new conceptual decay heat removal device was proposed. For the development of hybrid heat pipe operating at high temperature and high pressure conditions, the pressurized hybrid heat pipe was prepared and the thermal performances including operation limits of hybrid heat pipe were experimentally measured. Followings were obtained: (1) As operating pressure of the heat pipe increases, the evaporation heat transfer coefficient increases due to heat transfer with convective pool boiling mode. (2) Non-condensable gas charged in the test section for the pressurization lowered the condensation heat transfer by impeding the vapor flow to the condenser. (3) The deviations between experimentally measured flooding limits for hybrid heat pipes and the values from correlation for annular thermosyphon were observed.

Heat pipe heat exchangers in heat recovery systems

Energy Technology Data Exchange (ETDEWEB)

Stulc, P; Vasiliev, L L; Kiseljev, V G; Matvejev, Ju N

1985-01-01

The results of combined research and development activities of the National Research Institute for Machine Design, Prague, C.S.S.R. and the Institute for Heat and Mass Transfer, Minsk, U.S.S.R. concerning intensification heat pipes used in heat pipe heat exchangers are presented. This sort of research has been occasioned by increased interest in heat power economy trying to utilise waste heat produced by various technological processes. The developed heat pipes are deployed in construction of air-air, gas-air or gas-gas heat recovery exchangers in the field of air-engineering and air-conditioning. (author).

Squamous cell carcinoma arising in a mature cystic teratoma

Directory of Open Access Journals (Sweden)

Gupta Vishwanath

2009-04-01

Full Text Available Two cases of squamous cell carcinoma (SCC arising in a mature cystic teratoma (MCT are being discussed for their rarity and pattern of infiltration of tumor cells in the stroma (alpha mode, beta mode and gamma mode, which is a key factor in deciding the prognosis and patient survival.

On the equivalence of generalized least-squares approaches to the evaluation of measurement comparisons

Science.gov (United States)

Koo, A.; Clare, J. F.

2012-06-01

Analysis of CIPM international comparisons is increasingly being carried out using a model-based approach that leads naturally to a generalized least-squares (GLS) solution. While this method offers the advantages of being easier to audit and having general applicability to any form of comparison protocol, there is a lack of consensus over aspects of its implementation. Two significant results are presented that show the equivalence of three differing approaches discussed by or applied in comparisons run by Consultative Committees of the CIPM. Both results depend on a mathematical condition equivalent to the requirement that any two artefacts in the comparison are linked through a sequence of measurements of overlapping pairs of artefacts. The first result is that a GLS estimator excluding all sources of error common to all measurements of a participant is equal to the GLS estimator incorporating all sources of error, including those associated with any bias in the standards or procedures of the measuring laboratory. The second result identifies the component of uncertainty in the estimate of bias that arises from possible systematic effects in the participants' measurement standards and procedures. The expression so obtained is a generalization of an expression previously published for a one-artefact comparison with no inter-participant correlations, to one for a comparison comprising any number of repeat measurements of multiple artefacts and allowing for inter-laboratory correlations.

Dynamics of the middle atmosphere as observed by the ARISE project

Science.gov (United States)

Blanc, E.

2015-12-01

It has been strongly demonstrated that variations in the circulation of the middle atmosphere influence weather and climate all the way to the Earth's surface. A key part of this coupling occurs through the propagation and breaking of planetary and gravity waves. However, limited observations prevent to faithfully reproduce the dynamics of the middle atmosphere in numerical weather prediction and climate models. The main challenge of the ARISE (Atmospheric dynamics InfraStructure in Europe) project is to combine existing national and international observation networks including: the International infrasound monitoring system developed for the CTBT (Comprehensive nuclear-Test-Ban Treaty) verification, the NDACC (Network for the Detection of Atmospheric Composition Changes) lidar network, European observation infrastructures at mid latitudes (OHP observatory), tropics (Maïdo observatory), high latitudes (ALOMAR and EISCAT), infrasound stations which form a dense European network and satellites. The ARISE network is unique by its coverage (polar to equatorial regions in the European longitude sector), its altitude range (from troposphere to mesosphere and ionosphere) and the involved scales both in time (from seconds to tens of years) and space (from tens of meters to thousands of kilometers). Advanced data products are produced with the scope to assimilate data in the Weather Prediction models to improve future forecasts over weeks and seasonal time scales. ARISE observations are especially relevant for the monitoring of extreme events such as thunderstorms, volcanoes, meteors and at larger scales, deep convection and stratospheric warming events for physical processes description and study of long term evolution with climate change. Among the applications, ARISE fosters integration of innovative methods for remote detection of non-instrumented volcanoes including distant eruption characterization to provide notifications with reliable confidence indices to the

On the burnout in annular channels at non-uniform heat release distribution in length

International Nuclear Information System (INIS)

Ornatskij, A.P.; Chernobaj, V.A.; Vasil'ev, A.F.; Struts, G.V.

1982-01-01

The effect of axial heat release non-uniformity on the conditions of the burnout in annular channels is investigated. The investigation is carried out in annular channels with different laws of heat flux density distribution by channel length. The heat release non-uniformity coefficient was varied from 4.4 to 10, the pressure from 9.8 to 17.6 MPa, mass rate from 500 to 1700 kg (m 2 xS), liquid temperature (chemically desalted water) at the channel inlet constituted 30-300 deg C. The experiments have been performed at the test bench with a closed circulation circuit. The data obtained testify to the fact that under non-uniform heat release the influence of main operating parameters on the value of critical power is of the same character as under uniform heat release. The character of wall temperature variation by channel length before the burnout is determined by the form of heat supply temperature profile. The temperature maximum is observed in the region lying behind the cross section with maximum heat flux. The conclusion is drawn that the dominant influence on the position of the cross section in which the burnout arises is exerted by the form of heat flux density distribution by length. Independently of this distribution form the burnout developes when the vapour content near the wall reaches a limiting value

Transient thermal performance analysis of micro heat pipes

International Nuclear Information System (INIS)

Liu, Xiangdong; Chen, Yongping

2013-01-01

A theoretical analysis of transient fluid flow and heat transfer in a triangular micro heat pipes (MHP) has been conducted to study the thermal response characteristics. By introducing the system identification theory, the quantitative evaluation of the MHP's transient thermal performance is realized. The results indicate that the evaporation and condensation processes are both extended into the adiabatic section. During the start-up process, the capillary radius along axial direction of MHP decreases drastically while the liquid velocity increases quickly at the early transient stage and an approximately linear decrease in wall temperature arises along the axial direction. The MHP behaves as a first-order LTI control system with the constant input power as the 'step input' and the evaporator wall temperature as the 'output'. Two corresponding evaluation criteria derived from the control theory, time constant and temperature constant, are able to quantitatively evaluate the thermal response speed and temperature level of MHP under start-up, which show that a larger triangular groove's hydraulic diameter within 0.18–0.42 mm is able to accelerate the start-up and decrease the start-up temperature level of MHP. Additionally, the MHP starts up fastest using the fluid of ethanol and most slowly using the working fluid of methanol, and the start-up temperature reaches maximum level for acetone and minimum level for the methanol. -- Highlights: • Transient thermal response of micro heat pipe is simulated by an improved model. • Control theory is introduced to quantify the thermal response of micro heat pipe. • Evaluation criteria are proposed to represent thermal response of micro heat pipe. • Effects of groove dimensions and working fluids on start-up of micro heat pipe are evaluated

Dancing to death: A case of heat stroke.

Science.gov (United States)

Nadesan, K; Kumari, Chandra; Afiq, Mohd

2017-08-01

Heat stroke is a medical emergency which may lead to mortality unless diagnosed early and treated effectively. Heat stroke may manifest rapidly, hence making it difficult to differentiate it from other clinical causes in a collapsed victim. 1 We are presenting a case report of twelve patients who were admitted to our emergency department from a music festival held on 13-15th of March 2014. They developed complications arising from a combination of severe adverse weather condition, prolonged outdoor physical exertion due to long hours of dancing and drug-use, resulting in heat stroke. Three of them died while the remaining patients survived. Their condition was initially misdiagnosed as a classical illicit drug overdose. This was based on the history of drug ingestion by some of the patients who attended the music festival on that day. The information in this case report aims, to create awareness amongst members of the medical team on duty in outdoor events, pre hospital responders and ED physicians when treating and managing similar cases in the future. In addition it is intended to warn the organizers of such events to take adequate precautions to avoid such tragedies in the future. Copyright © 2017. Published by Elsevier Ltd.

Wireless Metal Detection and Surface Coverage Sensing for All-Surface Induction Heating

Directory of Open Access Journals (Sweden)

Veli Tayfun Kilic

2016-03-01

Full Text Available All-surface induction heating systems, typically comprising small-area coils, face a major challenge in detecting the presence of a metallic vessel and identifying its partial surface coverage over the coils to determine which of the coils to power up. The difficulty arises due to the fact that the user can heat vessels made of a wide variety of metals (and their alloys. To address this problem, we propose and demonstrate a new wireless detection methodology that allows for detecting the presence of metallic vessels together with uniquely sensing their surface coverages while also identifying their effective material type in all-surface induction heating systems. The proposed method is based on telemetrically measuring simultaneously inductance and resistance of the induction coil coupled with the vessel in the heating system. Here, variations in the inductance and resistance values for an all-surface heating coil loaded by vessels (made of stainless steel and aluminum at different positions were systematically investigated at different frequencies. Results show that, independent of the metal material type, unique identification of the surface coverage is possible at all freqeuncies. Additionally, using the magnitude and phase information extracted from the coupled coil impedance, unique identification of the vessel effective material is also achievable, this time independent of its surface coverage.

Intraosseous verrucous carcinoma arising from an orthokeratinized odontogenic keratocyst: A report of a rarest entity

Directory of Open Access Journals (Sweden)

Nagaraju Kamarthi

2016-01-01

Full Text Available Intraosseous verrucous carcinomas (VCs arising from odontogenic cysts are a rare entity. An unusual case of a VC arising from the orthokeratinized odontogenic cyst is described for the first time. The microscopic features of the lesion are presented.

Entanglement witnesses arising from exposed positive linear maps

OpenAIRE

Ha, Kil-Chan; Kye, Seung-Hyeok

2011-01-01

We consider entanglement witnesses arising from positive linear maps which generate exposed extremal rays. We show that every entanglement can be detected by one of these witnesses, and this witness detects a unique set of entanglement among those. Therefore, they provide a minimal set of witnesses to detect all entanglement in a sense. Furthermore, if those maps are indecomposable then they detect large classes of entanglement with positive partial transposes which have nonempty relative int...

High-Grade Leiomyosarcoma Arising in a Previously Replanted Limb

Directory of Open Access Journals (Sweden)

Tiffany J. Pan

2015-01-01

Full Text Available Sarcoma development has been associated with genetics, irradiation, viral infections, and immunodeficiency. Reports of sarcomas arising in the setting of prior trauma, as in burn scars or fracture sites, are rare. We report a case of a leiomyosarcoma arising in an arm that had previously been replanted at the level of the elbow joint following traumatic amputation when the patient was eight years old. He presented twenty-four years later with a 10.8 cm mass in the replanted arm located on the volar forearm. The tumor was completely resected and pathology examination showed a high-grade, subfascial spindle cell sarcoma diagnosed as a grade 3 leiomyosarcoma with stage pT2bNxMx. The patient underwent treatment with brachytherapy, reconstruction with a free flap, and subsequently chemotherapy. To the best of our knowledge, this is the first case report of leiomyosarcoma developing in a replanted extremity. Development of leiomyosarcoma in this case could be related to revascularization, scar formation, or chronic injury after replantation. The patient remains healthy without signs of recurrence at three-year follow-up.

Multiple Ectopic Hepatocellular Carcinomas Arising in the Abdominal Cavity

Directory of Open Access Journals (Sweden)

Toru Miyake

2012-09-01

Full Text Available Ectopic hepatocellular carcinoma (HCC is a very rare clinical entity that is defined as HCC arising from extrahepatic liver tissue. This report presents a case of ectopic multiple HCC arising in the abdominal cavity. A 42-year-old otherwise healthy male presented with liver dysfunction at a general health checkup. Both HCV antibody and hepatitis B surface antigen were negative. Laboratory examination showed elevations in serum alpha-fetoprotein and PIVKA-II. Ultrasonography and computed tomography revealed multiple nodular lesions in the abdominal cavity with ascites without a possible primary tumor. Exploratory laparoscopy was performed, which revealed bloody ascites and multiple brown nodular tumors measuring approximately 10 mm in size that were disseminated on the perineum and mesentery. A postoperative PET-CT scan was performed but it did not reveal any evidence of a tumor in the liver. The tumors resected from the peritoneum were diagnosed as HCC. The present case of HCC was thought to have possibly developed from ectopic liver on the peritoneum or mesentery.

Warm vegetarians? Heat waves and diet shifts in tadpoles.

Science.gov (United States)

Carreira, B M; Segurado, P; Orizaola, G; Gonçalves, N; Pinto, V; Laurila, A; Rebelo, R

2016-11-01

Temperature can play an important role in determining the feeding preferences of ectotherms. In light of the warmer temperatures arising with the current climatic changes, omnivorous ectotherms may perform diet shifts toward higher herbivory to optimize energetic intake. Such diet shifts may also occur during heat waves, which are projected to become more frequent, intense, and longer lasting in the future. Here, we investigated how heat waves of different duration affect feeding preferences in omnivorous anuran tadpoles and how these choices affect larval life history. In laboratory experiments, we fed tadpoles of three species on animal, plant, or mixed diet and exposed them to short heat waves (similar to the heat waves these species experience currently) or long heat waves (predicted to increase under climate change). We estimated the dietary choices of tadpoles fed on the mixed diet using stable isotopes and recorded tadpole survival and growth, larval period, and mass at metamorphosis. Tadpole feeding preferences were associated with their thermal background, with herbivory increasing with breeding temperature in nature. Patterns in survival, growth, and development generally support decreased efficiency of carnivorous diets and increased efficiency or higher relative quality of herbivorous diets at higher temperatures. All three species increased herbivory in at least one of the heat wave treatments, but the responses varied among species. Diet shifts toward higher herbivory were maladaptive in one species, but beneficial in the other two. Higher herbivory in omnivorous ectotherms under warmer temperatures may impact species differently and further contribute to changes in the structure and function of freshwater environments. © 2016 by the Ecological Society of America.

Survival of mutations arising during invasions.

Science.gov (United States)

Miller, Judith R

2010-03-01

When a neutral mutation arises in an invading population, it quickly either dies out or 'surfs', i.e. it comes to occupy almost all the habitat available at its time of origin. Beneficial mutations can also surf, as can deleterious mutations over finite time spans. We develop descriptive statistical models that quantify the relationship between the probability that a mutation will surf and demographic parameters for a cellular automaton model of surfing. We also provide a simple analytic model that performs well at predicting the probability of surfing for neutral and beneficial mutations in one dimension. The results suggest that factors - possibly including even abiotic factors - that promote invasion success may also increase the probability of surfing and associated adaptive genetic change, conditioned on such success.

[A case of carcinoma arising in a diverticulum of the transverse colon].

Science.gov (United States)

Nomi, Masako; Umemoto, Satoshi; Kikutake, Takashi; Hosaka, Seiji; Mase, Takahiro; Kawamoto, Shunji; Yoshida, Takahisa

2014-11-01

A 64 year-old woman presented with advanced, transverse colon cancer arising in the diverticulum. Tumor invasion extended beyond the serosa to the anal side of the colon. Anemia and fatigue progressed after 6 months of iron administration. The hemoglobin value was 5.3 g/dL and carcinoembryonic antigen (CEA) level was elevated to 44.2 ng/mL. A palpable and tender fist-sized mass was found in the right upper abdomen. Computed tomography (CT) revealed a low-density mass in the transverse colon invading beyond the serosa to the anal side of the colon. Right hemi-colectomy with lymph node dissection was performed. The resected specimen contained multiple diverticula including the one from which the tumor arose. Histological examination revealed a well-differentiated, tubular adenocarcinoma (UICC TNM T4bN0M0) arising in a transverse colon diverticulum. There has been no recurrence for 2 years. Colon cancer arising in a diverticulum may expand to the extra-serosa and easily invade to the adjacent organ. In such cases, malignancy should be considered.