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Sample records for minimizes tissue artefacts

  1. 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

  2. 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.

  3. 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.)

  4. 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....

  5. Analytical study of the effects of soft tissue artefacts on functional techniques to define axes of rotation.

    Science.gov (United States)

    De Rosario, Helios; Page, Álvaro; Besa, Antonio

    2017-09-06

    The accurate location of the main axes of rotation (AoR) is a crucial step in many applications of human movement analysis. There are different formal methods to determine the direction and position of the AoR, whose performance varies across studies, depending on the pose and the source of errors. Most methods are based on minimizing squared differences between observed and modelled marker positions or rigid motion parameters, implicitly assuming independent and uncorrelated errors, but the largest error usually results from soft tissue artefacts (STA), which do not have such statistical properties and are not effectively cancelled out by such methods. However, with adequate methods it is possible to assume that STA only account for a small fraction of the observed motion and to obtain explicit formulas through differential analysis that relate STA components to the resulting errors in AoR parameters. In this paper such formulas are derived for three different functional calibration techniques (Geometric Fitting, mean Finite Helical Axis, and SARA), to explain why each technique behaves differently from the others, and to propose strategies to compensate for those errors. These techniques were tested with published data from a sit-to-stand activity, where the true axis was defined using bi-planar fluoroscopy. All the methods were able to estimate the direction of the AoR with an error of less than 5°, whereas there were errors in the location of the axis of 30-40mm. Such location errors could be reduced to less than 17mm by the methods based on equations that use rigid motion parameters (mean Finite Helical Axis, SARA) when the translation component was calculated using the three markers nearest to the axis. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Triggering Artefacts

    DEFF Research Database (Denmark)

    Mogensen, Preben Holst; Robinson, Mike

    1995-01-01

    and adapting them to specific situations need not be ad hoc.Triggering artefacts are a way of systematically challenging both designers' preunderstandings and the conservatism of work practice. Experiences from the Great Belt tunnel and bridge project are used to illustrate howtriggering artefacts change...

  7. 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.

  8. 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.

  9. The normativity of artefacts

    NARCIS (Netherlands)

    Franssen, M.

    2006-01-01

    Part of the distinction between artefacts, objects made by humans for particular purposes, and natural objects is that artefacts are subject to normative judgements. A drill, say, can be a good drill or a poor drill, it can function well or correctly or it can malfunction. In this paper I

  10. Negotiating meaning through artefacts

    DEFF Research Database (Denmark)

    Tavella, Elena

    2015-01-01

    This research contributes to the domain of strategy making, specifically to unpacking the complexity of sociomateriality in strategy discourse. Scholars have emphasized the potential of artefacts to enhance sensemaking during strategizing. However there is a lack of insight into how artefacts...... and conversational aspects are linked at the micro‑level of discourse, also how artefacts and sensemaking shape one another. This research addresses this gap by empirically analyzing strategy discourse within a facilitated modelling workshop. Considering strategizing as a socially constructed activity, the author...... analyzes a workshop transcript to assess the extent to which stakeholders’ appropriation of artefacts supports them in engaging in negotiation of meaning with action implications. Moreover, how artefacts and negotiation of meaning shape one another is identified. The data suggest that appropriating...

  11. Joint kinematics estimation using a multi-body kinematics optimisation and an extended Kalman filter, and embedding a soft tissue artefact model.

    Science.gov (United States)

    Bonnet, Vincent; Richard, Vincent; Camomilla, Valentina; Venture, Gentiane; Cappozzo, Aurelio; Dumas, Raphaël

    2017-09-06

    To reduce the impact of the soft tissue artefact (STA) on the estimate of skeletal movement using stereophotogrammetric and skin-marker data, multi-body kinematics optimisation (MKO) and extended Kalman filters (EKF) have been proposed. This paper assessed the feasibility and efficiency of these methods when they embed a mathematical model of the STA and simultaneously estimate the ankle, knee and hip joint kinematics and the model parameters. A STA model was used that provides an estimate of the STA affecting the marker-cluster located on a body segment as a function of the kinematics of the adjacent joints. The MKO and the EKF were implemented with and without the STA model. To assess these methods, intra-cortical pin and skin markers located on the thigh, shank, and foot of three subjects and tracked during the stance phase of running were used. Embedding the STA model in MKO and EKF reduced the average RMS of marker tracking from 12.6 to 1.6mm and from 4.3 to 1.9mm, respectively, showing that a STA model trial-specific calibration is feasible. Nevertheless, with the STA model embedded in MKO, the RMS difference between the estimated and the reference joint kinematics determined from the pin markers slightly increased (from 2.0 to 2.1deg) On the contrary, when the STA model was embedded in the EKF, this RMS difference was slightly reduced (from 2.0 to 1.7deg) thus showing a better potentiality of this method to attenuate STA effects and improve the accuracy of joint kinematics estimate. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. 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.

  13. 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

  14. Minimalism

    CERN Document Server

    Obendorf, Hartmut

    2009-01-01

    The notion of Minimalism is proposed as a theoretical tool supporting a more differentiated understanding of reduction and thus forms a standpoint that allows definition of aspects of simplicity. This book traces the development of minimalism, defines the four types of minimalism in interaction design, and looks at how to apply it.

  15. 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...

  16. A minimal spatial cell lineage model of epithelium: tissue stratification and multi-stability

    Science.gov (United States)

    Yeh, Wei-Ting; Chen, Hsuan-Yi

    2018-05-01

    A minimal model which includes spatial and cell lineage dynamics for stratified epithelia is presented. The dependence of tissue steady state on cell differentiation models, cell proliferation rate, cell differentiation rate, and other parameters are studied numerically and analytically. Our minimal model shows some important features. First, we find that morphogen or mechanical stress mediated interaction is necessary to maintain a healthy stratified epithelium. Furthermore, comparing with tissues in which cell differentiation can take place only during cell division, tissues in which cell division and cell differentiation are decoupled can achieve relatively higher degree of stratification. Finally, our model also shows that in the presence of short-range interactions, it is possible for a tissue to have multiple steady states. The relation between our results and tissue morphogenesis or lesion is discussed.

  17. Charge and energy minimization in electrical/magnetic stimulation of nervous tissue.

    Science.gov (United States)

    Jezernik, Saso; Sinkjaer, Thomas; Morari, Manfred

    2010-08-01

    In this work we address the problem of stimulating nervous tissue with the minimal necessary energy at reduced/minimal charge. Charge minimization is related to a valid safety concern (avoidance and reduction of stimulation-induced tissue and electrode damage). Energy minimization plays a role in battery-driven electrical or magnetic stimulation systems (increased lifetime, repetition rates, reduction of power requirements, thermal management). Extensive new theoretical results are derived by employing an optimal control theory framework. These results include derivation of the optimal electrical stimulation waveform for a mixed energy/charge minimization problem, derivation of the charge-balanced energy-minimal electrical stimulation waveform, solutions of a pure charge minimization problem with and without a constraint on the stimulation amplitude, and derivation of the energy-minimal magnetic stimulation waveform. Depending on the set stimulus pulse duration, energy and charge reductions of up to 80% are deemed possible. Results are verified in simulations with an active, mammalian-like nerve fiber model.

  18. Shape memory alloy fixator system for suturing tissue in minimal access surgery.

    Science.gov (United States)

    Xu, W; Frank, T G; Stockham, G; Cuschieri, A

    1999-01-01

    A new technique for suturing human tissue is described in which tissue closure is achieved by means of small fixators made from shape memory alloy. The aim of the development is to provide an alternative to thread suturing in minimal access surgery, which is quicker and requires less skill to achieve the required suturing quality. The design of the fixators is described in terms of the thermal shape recovery of shape memory alloy and a novel form of finite element analysis, which uses a nonlinear elastic element for the material property. Thermal analysis of the fixators and surrounding tissue is used to predict the temperature distribution during and after the application of electric current heating. This was checked in an in vitro experiment, which confirmed that deployment caused no detectable collateral damage to surrounding tissue. In vivo animal studies on the use of the shape memory alloy fixator for suturing tissue are ongoing to establish safety and healing effects.

  19. GeLC-MS: A Sample Preparation Method for Proteomics Analysis of Minimal Amount of Tissue.

    Science.gov (United States)

    Makridakis, Manousos; Vlahou, Antonia

    2017-10-10

    Application of various proteomics methodologies have been implemented for the global and targeted proteome analysis of many different types of biological samples such as tissue, urine, plasma, serum, blood, and cell lines. Among the aforementioned biological samples, tissue has an exceptional role into clinical research and practice. Disease initiation and progression is usually located at the tissue level of different organs, making the analysis of this material very important for the understanding of the disease pathophysiology. Despite the significant advances in the mass spectrometry instrumentation, tissue proteomics still faces several challenges mainly due to increased sample complexity and heterogeneity. However, the most prominent challenge is attributed to the invasive procedure of tissue sampling which restricts the availability of fresh frozen tissue to minimal amounts and limited number of samples. Application of GeLC-MS sample preparation protocol for tissue proteomics analysis can greatly facilitate making up for these difficulties. In this chapter, a step by step guide for the proteomics analysis of minute amounts of tissue samples using the GeLC-MS sample preparation protocol, as applied by our group in the analysis of multiple different types of tissues (vessels, kidney, bladder, prostate, heart) is provided.

  20. Breast tissue classification in digital tomosynthesis images based on global gradient minimization and texture features

    Science.gov (United States)

    Qin, Xulei; Lu, Guolan; Sechopoulos, Ioannis; Fei, Baowei

    2014-03-01

    Digital breast tomosynthesis (DBT) is a pseudo-three-dimensional x-ray imaging modality proposed to decrease the effect of tissue superposition present in mammography, potentially resulting in an increase in clinical performance for the detection and diagnosis of breast cancer. Tissue classification in DBT images can be useful in risk assessment, computer-aided detection and radiation dosimetry, among other aspects. However, classifying breast tissue in DBT is a challenging problem because DBT images include complicated structures, image noise, and out-of-plane artifacts due to limited angular tomographic sampling. In this project, we propose an automatic method to classify fatty and glandular tissue in DBT images. First, the DBT images are pre-processed to enhance the tissue structures and to decrease image noise and artifacts. Second, a global smooth filter based on L0 gradient minimization is applied to eliminate detailed structures and enhance large-scale ones. Third, the similar structure regions are extracted and labeled by fuzzy C-means (FCM) classification. At the same time, the texture features are also calculated. Finally, each region is classified into different tissue types based on both intensity and texture features. The proposed method is validated using five patient DBT images using manual segmentation as the gold standard. The Dice scores and the confusion matrix are utilized to evaluate the classified results. The evaluation results demonstrated the feasibility of the proposed method for classifying breast glandular and fat tissue on DBT images.

  1. MINIMALLY INVASIVE SINGLE FLAP APPROACH WITH CONNECTIVE TISSUE WALL FOR PERIODONTAL REGENERATION

    Directory of Open Access Journals (Sweden)

    Kamen Kotsilkov

    2017-09-01

    Full Text Available INTRODUCTION: The destructive periodontal diseases are among the most prevalent in the human population. In some cases, bony defects are formed during the disease progression, thus sustaining deep periodontal pockets. The reconstruction of these defects is usually done with the classical techniques of bone substitutes placement and guided tissue regeneration. The clinical and histological data from the recent years, however, demonstrate the relatively low regenerative potential of these techniques. The contemporary approaches for periodontal regeneration rely on minimally invasive surgical protocols, aimed at complete tissue preservation in order to achieve and maintain primary closure and at stimulating the natural regenerative potential of the periodontal tissues. AIM: This presentation demonstrates the application of a new, minimally invasive, single flap surgical technique for periodontal regeneration in a clinical case with periodontitis and a residual deep intrabony defect. MATERIALS AND METHODS: A 37 years old patient presented with chronic generalised periodontitis. The initial therapy led to good control of the periodontal infection with a single residual deep periodontal pocket medially at 11 due to a deep intrabony defect. A single flap approach with an enamel matrix derivate application and a connective tissue wall technique were performed. The proper primary closure was obtained. RESULT: One month after surgery an initial mineralisation process in the defect was detected. At the third month, a complete clinical healing was observed. The radiographic control showed finished bone mineralisation and periodontal space recreation. CONCLUSION: In the limitation of the presented case, the minimally invasive surgical approach led to complete clinical healing and new bone formation, which could be proof for periodontal regeneration.

  2. 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

  3. 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)

  4. Flexible shape-memory scaffold for minimally invasive delivery of functional tissues

    Science.gov (United States)

    Montgomery, Miles; Ahadian, Samad; Davenport Huyer, Locke; Lo Rito, Mauro; Civitarese, Robert A.; Vanderlaan, Rachel D.; Wu, Jun; Reis, Lewis A.; Momen, Abdul; Akbari, Saeed; Pahnke, Aric; Li, Ren-Ke; Caldarone, Christopher A.; Radisic, Milica

    2017-10-01

    Despite great progress in engineering functional tissues for organ repair, including the heart, an invasive surgical approach is still required for their implantation. Here, we designed an elastic and microfabricated scaffold using a biodegradable polymer (poly(octamethylene maleate (anhydride) citrate)) for functional tissue delivery via injection. The scaffold’s shape memory was due to the microfabricated lattice design. Scaffolds and cardiac patches (1 cm × 1 cm) were delivered through an orifice as small as 1 mm, recovering their initial shape following injection without affecting cardiomyocyte viability and function. In a subcutaneous syngeneic rat model, injection of cardiac patches was equivalent to open surgery when comparing vascularization, macrophage recruitment and cell survival. The patches significantly improved cardiac function following myocardial infarction in a rat, compared with the untreated controls. Successful minimally invasive delivery of human cell-derived patches to the epicardium, aorta and liver in a large-animal (porcine) model was achieved.

  5. A minimal model of epithelial tissue dynamics and its application to the corneal epithelium

    Science.gov (United States)

    Henkes, Silke; Matoz-Fernandez, Daniel; Kostanjevec, Kaja; Coburn, Luke; Sknepnek, Rastko; Collinson, J. Martin; Martens, Kirsten

    Epithelial cell sheets are characterized by a complex interplay of active drivers, including cell motility, cell division and extrusion. Here we construct a particle-based minimal model tissue with only division/death dynamics and show that it always corresponds to a liquid state with a single dynamic time scale set by the division rate, and that no glassy phase is possible. Building on this, we construct an in-silico model of the mammalian corneal epithelium as such a tissue confined to a hemisphere bordered by the limbal stem cell zone. With added cell motility dynamics we are able to explain the steady-state spiral migration on the cornea, including the central vortex defect, and quantitatively compare it to eyes obtained from mice that are X-inactivation mosaic for LacZ.

  6. A review of medical robotics for minimally invasive soft tissue surgery.

    Science.gov (United States)

    Dogangil, G; Davies, B L; Rodriguez y Baena, F

    2010-01-01

    This paper provides an overview of recent trends and developments in medical robotics for minimally invasive soft tissue surgery, with a view to highlight some of the issues posed and solutions proposed in the literature. The paper includes a thorough review of the literature, which focuses on soft tissue surgical robots developed and published in the last five years (between 2004 and 2008) in indexed journals and conference proceedings. Only surgical systems were considered; imaging and diagnostic devices were excluded from the review. The systems included in this paper are classified according to the following surgical specialties: neurosurgery; eye surgery and ear, nose, and throat (ENT); general, thoracic, and cardiac surgery; gastrointestinal and colorectal surgery; and urologic surgery. The systems are also cross-classified according to their engineering design and robotics technology, which is included in tabular form at the end of the paper. The review concludes with an overview of the field, along with some statistical considerations about the size, geographical spread, and impact of medical robotics for soft tissue surgery today.

  7. 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

  8. Minimally invasive soft tissue release of foot and ankle contracture secondary to stroke.

    Science.gov (United States)

    Boffeli, Troy J; Collier, Rachel C

    2014-01-01

    Lower extremity contracture associated with stroke commonly results in a nonreducible, spastic equinovarus deformity of the foot and ankle. Rigid contracture deformity leads to gait instability, pain, bracing difficulties, and ulcerations. The classic surgical approach for stroke-related contracture of the foot and ankle has been combinations of tendon lengthening, tendon transfer, osteotomy, and joint fusion procedures. Recovery after traditional foot and ankle reconstructive surgery requires a period of non-weightbearing that is not typically practical for these patients. Little focus has been given in published studies on minimally invasive soft tissue release of contracture. We present the case of a 61-year-old female with an equinovarus foot contracture deformity secondary to stroke. The patient underwent Achilles tendon lengthening, posterior tibial tendon Z lengthening, and digital flexor tenotomy of each toe with immediate weightbearing in a walking boot, followed by transition to an ankle-foot orthosis. The surgical principles and technique tips are presented to demonstrate our minimally invasive approach to release of foot and ankle contracture secondary to stroke. The main goal of this approach is to improve foot and ankle alignment for ease of bracing, which, in turn, will improve gait, reduce the risk of falls, decrease pain, and avoid the development of pressure sores. Copyright © 2014 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

  9. Minimally invasive injectable short nanofibers of poly(glycerol sebacate) for cardiac tissue engineering

    International Nuclear Information System (INIS)

    Ravichandran, Rajeswari; Venugopal, Jayarama Reddy; Sundarrajan, Subramanian; Mukherjee, Shayanti; Sridhar, Radhakrishnan; Ramakrishna, Seeram

    2012-01-01

    Myocardial tissue lacks the ability to appreciably regenerate itself following myocardial infarction (MI) which ultimately results in heart failure. Current therapies can only retard the progression of disease and hence tissue engineering strategies are required to facilitate the engineering of a suitable biomaterial to repair MI. The aim of this study was to investigate the in vitro properties of an injectable biomaterial for the regeneration of infarcted myocardium. Fabrication of core/shell fibers was by co-axial electrospinning, with poly(glycerol sebacate) (PGS) as core material and poly-l-lactic acid (PLLA) as shell material. The PLLA was removed by treatment of the PGS/PLLA core/shell fibers with DCM:hexane (2:1) to obtain PGS short fibers. These PGS short fibers offer the advantage of providing a minimally invasive injectable technique for the regeneration of infarcted myocardium. The scaffolds were characterized by SEM, FTIR and contact angle and cell–scaffold interactions using cardiomyocytes. The results showed that the cardiac marker proteins actinin, troponin, myosin heavy chain and connexin 43 were expressed more on short PGS fibers compared to PLLA nanofibers. We hypothesized that the injection of cells along with short PGS fibers would increase cell transplant retention and survival within the infarct, compared to the standard cell injection system. (paper)

  10. Material culture - artefacts and daily life

    DEFF Research Database (Denmark)

    Roesdahl, Else; Verhaeghe, Frans

    2011-01-01

    A survey of main groups of medieval portable artefacts, with a focus on north-western and central Europe (including Scandinavia), and a discussion of methods and interpretations in artefact studies...

  11. 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

  12. Experiential Role of Artefacts in Cooperative Design

    OpenAIRE

    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 this case, artefacts not only improve efficiency or have a purely functional role (e.g. allowing people to complete tasks quickly), but the presence and manifestations of these artefacts bring quality...

  13. Artefacts and the performance of an exhibition

    DEFF Research Database (Denmark)

    Svabo, Connie

    2008-01-01

    The article explores the role of mediating artefacts in children's encounters with a museum of natural history. Using actor network theory it explores how a specific artefact shapes the way users relate to exhibited objects and how the artefact guides users' movements in the exhibition....... The mediated performance of an exhibition is explored through an empirical case....

  14. 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.

  15. Reduction of metallic coil artefacts in computed tomography body imaging: effects of a new single-energy metal artefact reduction algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Kidoh, Masafumi; Utsunomiya, Daisuke; Ikeda, Osamu; Tamura, Yoshitaka; Oda, Seitaro; Yuki, Hideaki; Nakaura, Takeshi; Hirai, Toshinori; Yamashita, Yasuyuki [Kumamoto University, Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto (Japan); Funama, Yoshinori [Kumamoto University, Department of Medical Physics, Faculty of Life Sciences, Kumamoto (Japan); Kawano, Takayuki [Kumamoto University Graduate School, Department of Neurosurgery, Faculty of Life Sciences Research, Kumamoto (Japan)

    2016-05-15

    We evaluated the effect of a single-energy metal artefact reduction (SEMAR) algorithm for metallic coil artefact reduction in body imaging. Computed tomography angiography (CTA) was performed in 30 patients with metallic coils (10 men, 20 women; mean age, 67.9 ± 11 years). Non-SEMAR images were reconstructed with iterative reconstruction alone, and SEMAR images were reconstructed with the iterative reconstruction plus SEMAR algorithms. We compared image noise around metallic coils and the maximum diameters of artefacts from coils between the non-SEMAR and SEMAR images. Two radiologists visually evaluated the metallic coil artefacts utilizing a four-point scale: 1 = extensive; 2 = strong; 3 = mild; 4 = minimal artefacts. The image noise and maximum diameters of the artefacts of the SEMAR images were significantly lower than those of the non-SEMAR images (65.1 ± 33.0 HU vs. 29.7 ± 10.3 HU; 163.9 ± 54.8 mm vs. 10.3 ± 19.0 mm, respectively; P < 0.001). Better visual scores were obtained with the SEMAR technique (3.4 ± 0.6 vs. 1.0 ± 0.0, P < 0.001). The SEMAR algorithm significantly reduced artefacts caused by metallic coils compared with the non-SEMAR algorithm. This technique can potentially increase CT performance for the evaluation of post-coil embolization complications. (orig.)

  16. Reduction of metallic coil artefacts in computed tomography body imaging: effects of a new single-energy metal artefact reduction algorithm

    International Nuclear Information System (INIS)

    Kidoh, Masafumi; Utsunomiya, Daisuke; Ikeda, Osamu; Tamura, Yoshitaka; Oda, Seitaro; Yuki, Hideaki; Nakaura, Takeshi; Hirai, Toshinori; Yamashita, Yasuyuki; Funama, Yoshinori; Kawano, Takayuki

    2016-01-01

    We evaluated the effect of a single-energy metal artefact reduction (SEMAR) algorithm for metallic coil artefact reduction in body imaging. Computed tomography angiography (CTA) was performed in 30 patients with metallic coils (10 men, 20 women; mean age, 67.9 ± 11 years). Non-SEMAR images were reconstructed with iterative reconstruction alone, and SEMAR images were reconstructed with the iterative reconstruction plus SEMAR algorithms. We compared image noise around metallic coils and the maximum diameters of artefacts from coils between the non-SEMAR and SEMAR images. Two radiologists visually evaluated the metallic coil artefacts utilizing a four-point scale: 1 = extensive; 2 = strong; 3 = mild; 4 = minimal artefacts. The image noise and maximum diameters of the artefacts of the SEMAR images were significantly lower than those of the non-SEMAR images (65.1 ± 33.0 HU vs. 29.7 ± 10.3 HU; 163.9 ± 54.8 mm vs. 10.3 ± 19.0 mm, respectively; P < 0.001). Better visual scores were obtained with the SEMAR technique (3.4 ± 0.6 vs. 1.0 ± 0.0, P < 0.001). The SEMAR algorithm significantly reduced artefacts caused by metallic coils compared with the non-SEMAR algorithm. This technique can potentially increase CT performance for the evaluation of post-coil embolization complications. (orig.)

  17. Hybrid piezoresistive-optical tactile sensor for simultaneous measurement of tissue stiffness and detection of tissue discontinuity in robot-assisted minimally invasive surgery

    Science.gov (United States)

    Bandari, Naghmeh M.; Ahmadi, Roozbeh; Hooshiar, Amir; Dargahi, Javad; Packirisamy, Muthukumaran

    2017-07-01

    To compensate for the lack of touch during minimally invasive and robotic surgeries, tactile sensors are integrated with surgical instruments. Surgical tools with tactile sensors have been used mainly for distinguishing among different tissues and detecting malignant tissues or tumors. Studies have revealed that malignant tissue is most likely stiffer than normal. This would lead to the formation of a sharp discontinuity in tissue mechanical properties. A hybrid piezoresistive-optical-fiber sensor is proposed. This sensor is investigated for its capabilities in tissue distinction and detection of a sharp discontinuity. The dynamic interaction of the sensor and tissue is studied using finite element method. The tissue is modeled as a two-term Mooney-Rivlin hyperelastic material. For experimental verification, the sensor was microfabricated and tested under the same conditions as of the simulations. The simulation and experimental results are in a fair agreement. The sensor exhibits an acceptable linearity, repeatability, and sensitivity in characterizing the stiffness of different tissue phantoms. Also, it is capable of locating the position of a sharp discontinuity in the tissue. Due to the simplicity of its sensing principle, the proposed hybrid sensor could also be used for industrial applications.

  18. 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.

  19. 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

  20. 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....

  1. Artefacts: Minecraft meets Collaborative Interactive Evolution

    DEFF Research Database (Denmark)

    Patrascu, Cristinel; Risi, Sebastian

    2016-01-01

    Procedural content generation has shown promise in a variety of different games. In this paper we introduce a new kind of game, called Artefacts, that combines a sandbox-like environment akin to Minecraft with the ability to interactively evolve unique three-dimensional building blocks. Artefacts...

  2. 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

  3. Surface-specific additive manufacturing test artefacts

    Science.gov (United States)

    Townsend, Andrew; Racasan, Radu; Blunt, Liam

    2018-06-01

    Many test artefact designs have been proposed for use with additive manufacturing (AM) systems. These test artefacts have primarily been designed for the evaluation of AM form and dimensional performance. A series of surface-specific measurement test artefacts designed for use in the verification of AM manufacturing processes are proposed here. Surface-specific test artefacts can be made more compact because they do not require the large dimensions needed for accurate dimensional and form measurements. The series of three test artefacts are designed to provide comprehensive information pertaining to the manufactured surface. Measurement possibilities include deviation analysis, surface texture parameter data generation, sub-surface analysis, layer step analysis and build resolution comparison. The test artefacts are designed to provide easy access for measurement using conventional surface measurement techniques, for example, focus variation microscopy, stylus profilometry, confocal microscopy and scanning electron microscopy. Additionally, the test artefacts may be simply visually inspected as a comparative tool, giving a fast indication of process variation between builds. The three test artefacts are small enough to be included in every build and include built-in manufacturing traceability information, making them a convenient physical record of the build.

  4. 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.)

  5. 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

  6. Needle-tissue interactive mechanism and steering control in image-guided robot-assisted minimally invasive surgery: a review.

    Science.gov (United States)

    Li, Pan; Yang, Zhiyong; Jiang, Shan

    2018-06-01

    Image-guided robot-assisted minimally invasive surgery is an important medicine procedure used for biopsy or local target therapy. In order to reach the target region not accessible using traditional techniques, long and thin flexible needles are inserted into the soft tissue which has large deformation and nonlinear characteristics. However, the detection results and therapeutic effect are directly influenced by the targeting accuracy of needle steering. For this reason, the needle-tissue interactive mechanism, path planning, and steering control are investigated in this review by searching literatures in the last 10 years, which results in a comprehensive overview of the existing techniques with the main accomplishments, limitations, and recommendations. Through comprehensive analyses, surgical simulation for insertion into multi-layer inhomogeneous tissue is verified as a primary and propositional aspect to be explored, which accurately predicts the nonlinear needle deflection and tissue deformation. Investigation of the path planning of flexible needles is recommended to an anatomical or a deformable environment which has characteristics of the tissue deformation. Nonholonomic modeling combined with duty-cycled spinning for needle steering, which tracks the tip position in real time and compensates for the deviation error, is recommended as a future research focus in the steering control in anatomical and deformable environments. Graphical abstract a Insertion force when the needle is inserted into soft tissue. b Needle deflection model when the needle is inserted into soft tissue [68]. c Path planning in anatomical environments [92]. d Duty-cycled spinning incorporated in nonholonomic needle steering [64].

  7. Hard dental tissue minimal-invasive preparation using contemporary polymer rotating instruments and laser

    Directory of Open Access Journals (Sweden)

    Beloica Miloš

    2014-01-01

    Full Text Available Goal of contemporary dentistry is to decrease the patient’s discomfort during treatment. Dentists aim to achieve maximum with the newly developed dental materials as well as with new cavity preparation techniques in the shortest time span. Since the development of the first constructed borer (drilling machine for caries removal, the preparation techniques have considerably changed. The progress of dental materials as well as the cavity preparation techniques has led us to contemporary carbide tungsten and diamond borers that are used with obligatory water cooling. The innovation within this field represents newly developed polymer borers that can detect the difference between carious lesions and healthy tooth structure. In this way the cavity preparation may be performed without damaging dental healthy tissue. This is possible owing to their hardness which is lower than the hardness of intact dentin. Polymer borer preparation is painless with less vibration, while the increase in temperature is negligible. Lasers have been used in clinical dentistry since 1980s so it can be said that they represent a new technology. The function of lasers is based on ablation which requires water. Erbium lasers have shown the highest potential with their ability to produce effective ablation of hard dental tissues. Laser application in dentistry requires special training as well as some protective measures. Laser advantages, compared to traditional preparation techniques, involve the absence of vibration, painless preparation, possibility of preparation without anesthetic and easier patient’s adjustment to dental intervention which is of importance, especially in pediatric dentistry. [Projekat Ministarstva nauke Republike Srbije, br. 46009

  8. 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....

  9. Optical clearing of vaginal tissues, ex vivo, for minimally invasive laser treatment of female stress urinary incontinence

    Science.gov (United States)

    Chang, Chun-Hung; Myers, Erinn M.; Kennelly, Michael J.; Fried, Nathaniel M.

    2017-01-01

    Near-infrared laser energy in conjunction with applied tissue cooling is being investigated for thermal remodeling of the endopelvic fascia during minimally invasive treatment of female stress urinary incontinence. Previous computer simulations of light transport, heat transfer, and tissue thermal damage have shown that a transvaginal approach is more feasible than a transurethral approach. However, results were suboptimal, and some undesirable thermal insult to the vaginal wall was still predicted. This study uses experiments and computer simulations to explore whether application of an optical clearing agent (OCA) can further improve optical penetration depth and completely preserve the vaginal wall during subsurface treatment of the endopelvic fascia. Several different mixtures of OCA's were tested, and 100% glycerol was found to be the optimal agent. Optical transmission studies, optical coherence tomography, reflection spectroscopy, and computer simulations [including Monte Carlo (MC) light transport, heat transfer, and Arrhenius integral model of thermal damage] using glycerol were performed. The OCA produced a 61% increase in optical transmission through porcine vaginal wall at 37°C after 30 min. The MC model showed improved energy deposition in endopelvic fascia using glycerol. Without OCA, 62%, 37%, and 1% of energy was deposited in vaginal wall, endopelvic fascia, and urethral wall, respectively, compared with 50%, 49%, and 1% using OCA. Use of OCA also resulted in 0.5-mm increase in treatment depth, allowing potential thermal tissue remodeling at a depth of 3 mm with complete preservation of the vaginal wall.

  10. 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)

  11. 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...

  12. 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.

  13. 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.

  14. Minimally invasive distal linear metatarsal osteotomy combined with selective release of lateral soft tissue for severe hallux valgus.

    Science.gov (United States)

    Seki, Hiroyuki; Suda, Yasunori; Takeshima, Kenichiro; Kokubo, Tetsuro; Ishii, Ken; Nakamura, Masaya; Matsumoto, Morio; Niki, Yasuo

    2018-03-21

    Minimally invasive techniques for hallux valgus have been widely used to treat mild to moderate hallux valgus deformities. The purpose of this study was to evaluate the clinical and radiographic outcomes of distal linear metatarsal osteotomy (DLMO), which is one of the minimally invasive techniques, for severe hallux valgus. 95 patients (141 feet) with severe hallux valgus underwent DLMOs. Lateral soft tissue release (LSTR) was performed at the same time for the cases selected by an original manual test. The satisfaction level, the Japanese Society of Surgery of the Foot (JSSF) hallux scale score, and weight-bearing radiographs of the foot were assessed preoperatively and after more than 24 months. In addition, the clinical and radiographic outcomes were compared among three groups divided by the kind of LSTR: no LSTR; manual correction; and open release through skin incision. Although the first metatarsal bone was significantly shortened, dorsiflexed, and elevated on postoperative radiographs, the rate of satisfaction was 87.2% (123/141), and the mean JSSF hallux scale score improved significantly from 60.4 (44-73) to 90.4 (65-100). The mean hallux valgus and intermetatarsal angles also improved significantly from 45.5° (40.0-60.0°) to 10.3° (-28.0-40.9°) and from 19.9° (14.0-28.7°) to 8.3° (-1.6-18.5°), respectively. Delayed union (18 feet), metatarsalgia (16 feet), recurrence (22 feet), and hallux varus (22 feet) were observed, and they were more obvious in DLMO combined with open release through a skin incision. DLMO combined selectively with LSTR is an effective procedure for correcting severe hallux valgus. However, the indication for open release with DLMO should be considered carefully. Copyright © 2018. Published by Elsevier B.V.

  15. 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

    approaches were applied in this research for dosimetric evaluation on CT images with severe metal artefacts. The first part of the research used a water phantom with four iodine syringes. Two sets of plans, multi-arc plans and single-arc plans, using the Volumetric Modulated Arc therapy (VMAT) technique were designed to avoid or minimize influences from high-density objects. The second part of the research used projection-based MAR Algorithm and the Dual-Energy Method. Calculated Doses (Mean, Minimum, and Maximum Doses) to the planning treatment volume (PTV) were compared and homogeneity index (HI) calculated. Results: (1) Without the GSI-based MAR application, a percent error between mean dose and the absolute dose ranging from 3.4-5.7% per fraction was observed. In contrast, the error was decreased to a range of 0.09-2.3% per fraction with the GSI-based MAR algorithm. There was a percent difference ranging from 1.7-4.2% per fraction between with and without using the GSI-based MAR algorithm. (2) A range of 0.1-3.2% difference was observed for the maximum dose values, 1.5-10.4% for minimum dose difference, and 1.4-1.7% difference on the mean doses. Homogeneity indexes (HI) ranging from 0.068-0.065 for dual-energy method and 0.063-0.141 with projection-based MAR algorithm were also calculated. Conclusion: (1) Percent error without using the GSI-based MAR algorithm may deviate as high as 5.7%. This error invalidates the goal of Radiation Therapy to provide a more precise treatment. Thus, GSI-based MAR algorithm was desirable due to its better dose calculation accuracy. (2) Based on direct numerical observation, there was no apparent deviation between the mean doses of different techniques but deviation was evident on the maximum and minimum doses. The HI for the dual-energy method almost achieved the desirable null values. In conclusion, the Dual-Energy method gave better dose calculation accuracy to the planning treatment volume (PTV) for images with metal artefacts than

  16. Model output: fact or artefact?

    Science.gov (United States)

    Melsen, Lieke

    2015-04-01

    As a third-year PhD-student, I relatively recently entered the wonderful world of scientific Hydrology. A science that has many pillars that directly impact society, for example with the prediction of hydrological extremes (both floods and drought), climate change, applications in agriculture, nature conservation, drinking water supply, etcetera. Despite its demonstrable societal relevance, hydrology is often seen as a science between two stools. Like Klemeš (1986) stated: "By their academic background, hydrologists are foresters, geographers, electrical engineers, geologists, system analysts, physicists, mathematicians, botanists, and most often civil engineers." Sometimes it seems that the engineering genes are still present in current hydrological sciences, and this results in pragmatic rather than scientific approaches for some of the current problems and challenges we have in hydrology. Here, I refer to the uncertainty in hydrological modelling that is often neglected. For over thirty years, uncertainty in hydrological models has been extensively discussed and studied. But it is not difficult to find peer-reviewed articles in which it is implicitly assumed that model simulations represent the truth rather than a conceptualization of reality. For instance in trend studies, where data is extrapolated 100 years ahead. Of course one can use different forcing datasets to estimate the uncertainty of the input data, but how to prevent that the output is not a model artefact, caused by the model structure? Or how about impact studies, e.g. of a dam impacting river flow. Measurements are often available for the period after dam construction, so models are used to simulate river flow before dam construction. Both are compared in order to qualify the effect of the dam. But on what basis can we tell that the model tells us the truth? Model validation is common nowadays, but validation only (comparing observations with model output) is not sufficient to assume that a

  17. 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

  18. 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 ...

  19. 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...

  20. 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

  1. 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....

  2. 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...

  3. 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...

  4. 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....

  5. 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.)

  6. 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...

  7. Metal artefact reduction for accurate tumour delineation in radiotherapy

    DEFF Research Database (Denmark)

    Kovacs, David Gergely; Rechner, Laura A.; Appelt, Ane L.

    2018-01-01

    Background and purpose: Two techniques for metal artefact reduction for computed tomography were studied in order to identify their impact on tumour delineation in radiotherapy. Materials and methods: Using specially designed phantoms containing metal implants (dental, spine and hip) as well...... delineation significantly (pmetal implant....... as patient images, we investigated the impact of two methods for metal artefact reduction on (A) the size and severity of metal artefacts and the accuracy of Hounsfield Unit (HU) representation, (B) the visual impact of metal artefacts on image quality and (C) delineation accuracy. A metal artefact reduction...

  8. 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.

  9. 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

  10. 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.

  11. 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

  12. 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.

  13. From artefact to effect: the organising effects of artefacts on teams.

    Science.gov (United States)

    Berlin, Johan M; Carlström, Eric D

    2010-01-01

    Earlier studies have identified artefacts, but have only to a lesser degree looked at their effects. The purpose of this paper is to investigate how artefacts contribute to organisation. A trauma team at a university hospital has been observed and its members interviewed. The trauma team showed itself to be rich on artefacts since it had strong internal driving forces, high legitimacy, and tried to live up to high expectations from the outside. Its members were motivated to be in the forefront of trauma care. Through renewal, the team succeeded in maintaining demarcation. It also succeeded in systemising internal work tasks and made for itself a position in relation to the outside. The team's capacity, however, came to be limited by internal conflicts and battles for prestige. The study shows that informal logic has a strong influence on teams. Teamwork contributed to the development of organisational structure and motivation for the personnel. Earlier studies advocate the important role of artefacts in order to communicate, collaborate, negotiate or coordinate activities. The conclusion is that artefacts also have an organising and developing effect on teams in a fragmented and differentiated healthcare.

  14. Minimally invasive collection of adipose tissue facilitates the study of eco-physiology in small-bodied mammals

    Science.gov (United States)

    Jeff Clerc; Theodore J. Weller; Jeffrey B. Schineller; Joseph M. Szewczak; Diana Fisher

    2016-01-01

    Adipose tissue is the primary fuel storage for vertebrates and is an important component of energy budgets during periods of peak energetic demands. Investigating the composition of adipose tissue can provide information about energetics, migration, reproduction, and other life-history traits. Until now, most field methods for sampling the adipose tissue of...

  15. A study of artefacts in simultaneous PET and MR imaging using a prototype MR compatible PET scanner

    International Nuclear Information System (INIS)

    Slates, R.B.; Farahani, K.; Marsden, P.K.; Taylor, J.; Summers, P.E.; Williams, S.; Beech, J.

    1999-01-01

    We have assessed the possibility of artefacts that can arise in attempting to perform simultaneous positron emission tomography (PET) and magnetic resonance imaging (MRI) using a small prototype MR compatible PET scanner (McPET). In these experiments, we examine MR images for any major artefacts or loss in image quality due to inhomogeneities in the magnetic field, radiofrequency interference or susceptibility effects caused by operation of the PET system inside the MR scanner. In addition, possible artefacts in the PET images caused by the static and time-varying magnetic fields or radiofrequency interference from the MR system were investigated. Biological tissue and a T 2 -weighted spin echo sequence were used to examine susceptibility artefacts due to components of the McPET scanner (scintillator, optical fibres) situated in the MR field of view. A range of commonly used MR pulse sequences was studied while acquiring PET data to look for possible artefacts in either the PET or MR images. Other than a small loss in signal-to-noise using gradient echo sequences, there was no significant interaction between the two imaging systems. Simultaneous PET and MR imaging of simple phantoms was also carried out in different MR systems with field strengths ranging from 0.2 to 4.7 T. The results of these studies demonstrate that it is possible to acquire PET and MR images simultaneously, without any significant artefacts or loss in image quality, using our prototype MR compatible PET scanner. (author)

  16. Challenges in contrast-enhanced spectral mammography interpretation: artefacts lexicon.

    Science.gov (United States)

    Yagil, Y; Shalmon, A; Rundstein, A; Servadio, Y; Halshtok, O; Gotlieb, M; Sklair-Levy, M

    2016-05-01

    To review and describe commonly encountered artefacts in contrast-enhanced spectral mammography (CESM). This retrospective study included 200 women who underwent CESM examinations for screening and diagnostic purposes. Analysis was performed on the image data sets of these women, comprising of a total of 774 subtracted images. Images were reviewed with focus on the presence of four artefacts: rim ("breast within breast"), ripple (black and white lines), axillary line, and skin-line enhancement (skin-line highlighting). Statistical cross-correlation and association with acquisition parameters (tube current, tube voltage, compression force, breast thickness, paddle size) was compared using Fisher's exact test and t-test. The rim artefact was highly common (97-99%) in every projection. The ripple artefact was increasingly more common on the oblique projections (80-82%) and found to be associated with higher breast thickness values. The axillary line artefact was detected only on oblique projections (63%) and associated with the use of a small compression paddle. The skin-line enhancement artefact was seen in 19-46% of projections. None of the artefacts interfered with image interpretation. Two main artefacts commonly seen on CESM are rim and ripple artefacts. They do not hamper with image interpretation. It is important to be aware of them and prevent misinterpretation of these artefacts as real breast pathology. Copyright © 2016 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

  17. Development and Feasibility Testing of Image-Guided Minimally Invasive Tissue for Diagnosis Treatment of Benign and Malignant Breast Disease

    Science.gov (United States)

    Jeffrey, Stefanie S.

    1999-01-01

    Dr. Robert Mah and Dr. Stefanie Jeffrey worked on the development of the NASA Smart Probe in its application as a device to measure and interpret physiologic and image-based parameters of breast tissue. To date the following has been achieved: 1 . Choice of candidate sensors to be tested in breast tissue. 2. Preliminary designs for probe tip, specifically use of different tip shapes, cutting edges, and sensor configuration. 3. Design of sonographic guidance system. 4. Design of data extraction and analysis tool using scanned information of images of the breast tissue to provide a higher dimension of information for breast tissue characterization and interpretation. 5. Initial ex-vivo (fruit and tofu) and in-vivo (rodent) testing to confirm unique substance and tissue characterization by the Smart Probe software.

  18. 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...

  19. 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...

  20. 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...

  1. A minimal set of tissue-specific hypomethylated CpGs constitute epigenetic signatures of developmental programming.

    Directory of Open Access Journals (Sweden)

    Alejandro Colaneri

    Full Text Available Cell specific states of the chromatin are programmed during mammalian development. Dynamic DNA methylation across the developing embryo guides a program of repression, switching off genes in most cell types. Thus, the majority of the tissue specific differentially methylated sites (TS-DMS must be un-methylated CpGs.Comparison of expanded Methyl Sensitive Cut Counting data (eMSCC among four tissues (liver, testes, brain and kidney from three C57BL/6J mice, identified 138,052 differentially methylated sites of which 23,270 contain CpGs un-methylated in only one tissue (TS-DMS. Most of these CpGs were located in intergenic regions, outside of promoters, CpG islands or their shores, and up to 20% of them overlapped reported active enhancers. Indeed, tissue-specific enhancers were up to 30 fold enriched in TS-DMS. Testis showed the highest number of TS-DMS, but paradoxically their associated genes do not appear to be specific to the germ cell functions, but rather are involved in organism development. In the other tissues the differentially methylated genes are associated with tissue-specific physiological or anatomical functions. The identified sets of TS-DMS quantify epigenetic distances between tissues, generated during development. We applied this concept to measure the extent of reprogramming in the liver of mice exposed to in utero or early postnatal nutritional stress. Different protocols of food restriction reprogrammed the liver methylome in different but reproducible ways.Thus, each identified set of differentially methylated sites constituted an epigenetic signature that traced the developmental programing or the early nutritional reprogramming of each exposed mouse. We propose that our approach has the potential to outline a number of disease-associated epigenetic states. The composition of differentially methylated CpGs may vary with each situation, behaving as a composite variable, which can be used as a pre-symptomatic marker for

  2. Minimal health impacts but detectable tissue residues after exposure of northern leopard frogs (Lithobates pipiens) to commercial naphthenic acids

    International Nuclear Information System (INIS)

    Hersikorn, B.; Young, R.; Fedorak, P.; Smits, J.

    2010-01-01

    This presentation reported on a study that examined whether naphthenic acids (NAs) are a toxic component in oil sands process-affected materials (OSPM). The study investigated the toxicity of commercial (Refined Merichem) NAs to native amphibians (northern leopard frogs) exposed to saline conditions comparable to those of reclaimed wetlands on oil sand leases. Gas chromatography-mass spectroscopy analysis showed that the exposure of frogs to NAs solutions for 28 days resulted in proportional NA concentrations in extracts of frog muscle tissue. Biological assays were performed to determine if the increasing exposure to NAs caused a proportional compromise in the health of test animals. The innate immune function, thyroid hormones, and hepatic detoxification enzyme induction did not differ in response to increased tissue concentrations of NAs. The commercial NAs were absorbed and deposited in muscle tissue. It was concluded that NAs play only a small, if any, role in the toxicity of OSPM to frogs.

  3. 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...

  4. 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...

  5. 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.

  6. 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)

  7. 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)

  8. The Application of Minimally Invasive Devices with Nanostructured Surface Functionalization: Antisticking Behavior on Devices and Liver Tissue Interface in Rat

    Directory of Open Access Journals (Sweden)

    Li-Hsiang Lin

    2015-01-01

    Full Text Available This study investigated the thermal injury and adhesion property of a novel electrosurgery of liver using copper-doped diamond-like carbon (DLC-Cu surface treatment. It is necessary to reduce the thermal damage of surrounding tissues for clinical electrosurgeries. The surface morphologies of stainless steel (SS coated with DLC (DLC-Cu-SS films were characterized by scanning electron microscopy (SEM and transmission electron microscopy (TEM. Bionic liver models were reconstructed using magnetic resonance imaging (MRI to simulate electrosurgery. Cell cytotoxicity assays showed that the DLC-Cu thin film was nontoxic. The temperature of tissue decreased significantly with use of the electrosurgical device with nanostructured DLC-Cu films and increased with increasing thickness of the films. Thermography revealed that the surgical temperature in the DLC-Cu-SS electrosurgical device was significantly lower than that in the untreated device in the animal model. Moreover, compared to the SS electrosurgical device, the DLC-Cu-SS electrosurgical device caused a relatively small injury area and lateral thermal effect. The results indicate that the DLC-Cu-SS electrosurgical device decreases excessive thermal injury and ensures homogeneous temperature transformation in the tissues.

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. 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

  14. 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.

  15. Metal artefact reduction in gemstone spectral imaging dual-energy CT with and without metal artefact reduction software

    International Nuclear Information System (INIS)

    Lee, Young Han; Song, Ho-Taek; Kim, Sungjun; Suh, Jin-Suck; Park, Kwan Kyu

    2012-01-01

    To assess the usefulness of gemstone spectral imaging (GSI) dual-energy CT (DECT) with/without metal artefact reduction software (MARs). The DECTs were performed using fast kV-switching GSI between 80 and 140 kV. The CT data were retro-reconstructed with/without MARs, by different displayed fields-of-view (DFOV), and with synthesised monochromatic energy in the range 40-140 keV. A phantom study of size and CT numbers was performed in a titanium plate and a stainless steel plate. A clinical study was performed in 26 patients with metallic hardware. All images were retrospectively reviewed in terms of the visualisation of periprosthetic regions and the severity of beam-hardening artefacts by using a five-point scale. The GSI-MARs reconstruction can markedly reduce the metal-related artefacts, and the image quality was affected by the prosthesis composition and DFOV. The spectral CT numbers of the prosthesis and periprosthetic regions showed different patterns on stainless steel and titanium plates. Dual-energy CT with GSI-MARs can reduce metal-related artefacts and improve the delineation of the prosthesis and periprosthetic region. We should be cautious when using GSI-MARs because the image quality was affected by the prosthesis composition, energy (in keV) and DFOV. The metallic composition and size should be considered in metallic imaging with GSI-MARs reconstruction. circle Metal-related artefacts can be troublesome on musculoskeletal computed tomography (CT). circle Gemstone spectral imaging (GSI) with dual-energy CT (DECT) offers a novel solution circle GSI and metallic artefact reduction software (GSI-MAR) can markedly reduce these artefacts. circle However image quality is influenced by the prosthesis composition and other parameters. circle We should be aware about potential overcorrection when using GSI-MARs. (orig.)

  16. 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..

  17. Tissue

    Directory of Open Access Journals (Sweden)

    David Morrissey

    2012-01-01

    Full Text Available Purpose. In vivo gene therapy directed at tissues of mesenchymal origin could potentially augment healing. We aimed to assess the duration and magnitude of transene expression in vivo in mice and ex vivo in human tissues. Methods. Using bioluminescence imaging, plasmid and adenoviral vector-based transgene expression in murine quadriceps in vivo was examined. Temporal control was assessed using a doxycycline-inducible system. An ex vivo model was developed and optimised using murine tissue, and applied in ex vivo human tissue. Results. In vivo plasmid-based transgene expression did not silence in murine muscle, unlike in liver. Although maximum luciferase expression was higher in muscle with adenoviral delivery compared with plasmid, expression reduced over time. The inducible promoter cassette successfully regulated gene expression with maximum levels a factor of 11 greater than baseline. Expression was re-induced to a similar level on a temporal basis. Luciferase expression was readily detected ex vivo in human muscle and tendon. Conclusions. Plasmid constructs resulted in long-term in vivo gene expression in skeletal muscle, in a controllable fashion utilising an inducible promoter in combination with oral agents. Successful plasmid gene transfection in human ex vivo mesenchymal tissue was demonstrated for the first time.

  18. The use of time-of-flight camera for navigating robots in computer-aided surgery: monitoring the soft tissue envelope of minimally invasive hip approach in a cadaver study.

    Science.gov (United States)

    Putzer, David; Klug, Sebastian; Moctezuma, Jose Luis; Nogler, Michael

    2014-12-01

    Time-of-flight (TOF) cameras can guide surgical robots or provide soft tissue information for augmented reality in the medical field. In this study, a method to automatically track the soft tissue envelope of a minimally invasive hip approach in a cadaver study is described. An algorithm for the TOF camera was developed and 30 measurements on 8 surgical situs (direct anterior approach) were carried out. The results were compared to a manual measurement of the soft tissue envelope. The TOF camera showed an overall recognition rate of the soft tissue envelope of 75%. On comparing the results from the algorithm with the manual measurements, a significant difference was found (P > .005). In this preliminary study, we have presented a method for automatically recognizing the soft tissue envelope of the surgical field in a real-time application. Further improvements could result in a robotic navigation device for minimally invasive hip surgery. © The Author(s) 2014.

  19. 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.

  20. 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...

  1. 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....

  2. 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.)

  3. 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.)

  4. 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

  5. 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

  6. 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.

  7. 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

  8. 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)

  9. 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

  10. Minimal surfaces

    CERN Document Server

    Dierkes, Ulrich; Sauvigny, Friedrich; Jakob, Ruben; Kuster, Albrecht

    2010-01-01

    Minimal Surfaces is the first volume of a three volume treatise on minimal surfaces (Grundlehren Nr. 339-341). Each volume can be read and studied independently of the others. The central theme is boundary value problems for minimal surfaces. The treatise is a substantially revised and extended version of the monograph Minimal Surfaces I, II (Grundlehren Nr. 295 & 296). The first volume begins with an exposition of basic ideas of the theory of surfaces in three-dimensional Euclidean space, followed by an introduction of minimal surfaces as stationary points of area, or equivalently

  11. Minimally invasive orthognathic surgery.

    Science.gov (United States)

    Resnick, Cory M; Kaban, Leonard B; Troulis, Maria J

    2009-02-01

    Minimally invasive surgery is defined as the discipline in which operative procedures are performed in novel ways to diminish the sequelae of standard surgical dissections. The goals of minimally invasive surgery are to reduce tissue trauma and to minimize bleeding, edema, and injury, thereby improving the rate and quality of healing. In orthognathic surgery, there are two minimally invasive techniques that can be used separately or in combination: (1) endoscopic exposure and (2) distraction osteogenesis. This article describes the historical developments of the fields of orthognathic surgery and minimally invasive surgery, as well as the integration of the two disciplines. Indications, techniques, and the most current outcome data for specific minimally invasive orthognathic surgical procedures are presented.

  12. 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...

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. 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.)

  19. 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...

  20. 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.

  1. 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.

  2. 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...

  3. 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.

  4. 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)

  5. 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.)

  6. 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.)

  7. 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...

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. Flow cytometric characterization of culture expanded multipotent mesenchymal stromal cells (MSCs) from horse adipose tissue: towards the definition of minimal stemness criteria.

    Science.gov (United States)

    Pascucci, L; Curina, G; Mercati, F; Marini, C; Dall'Aglio, C; Paternesi, B; Ceccarelli, P

    2011-12-15

    In the last decades, multipotent mesenchymal progenitor cells have been isolated from many adult tissues of different species. The International Society for Cellular Therapy (ISCT) has recently established that multipotent mesenchymal stromal cells (MSCs) is the currently recommended designation. In this study, we used flow cytometry to evaluate the expression of several molecules related to stemness (CD90, CD44, CD73 and STRO-1) in undifferentiated, early-passaged MSCs isolated from adipose tissue of four donor horses (AdMSCs). The four populations unanimously expressed high levels of CD90 and CD44. On the contrary, they were unexpectedly negative to CD73. A small percentage of the cells, finally, showed the expression of STRO-1. This last result might be due to the existence of a small subpopulation of STRO-1+ cells or to a poor cross-reactivity of the antibody. A remarkable donor-to-donor consistency and reproducibility of these findings was demonstrated. The data presented herein support the idea that equine AdMSCs may be easily isolated and selected by adherence to tissue culture plastic and exhibit a surface profile characterized by some peculiar differences in comparison to those described in other species. Continued characterization of these cells will help to clarify several aspects of their biology and may ultimately enable the isolation of specific, purified subpopulations. Copyright © 2011 Elsevier B.V. All rights reserved.

  14. Taxonomic minimalism.

    Science.gov (United States)

    Beattle, A J; Oliver, I

    1994-12-01

    Biological surveys are in increasing demand while taxonomic resources continue to decline. How much formal taxonomy is required to get the job done? The answer depends on the kind of job but it is possible that taxonomic minimalism, especially (1) the use of higher taxonomic ranks, (2) the use of morphospecies rather than species (as identified by Latin binomials), and (3) the involvement of taxonomic specialists only for training and verification, may offer advantages for biodiversity assessment, environmental monitoring and ecological research. As such, formal taxonomy remains central to the process of biological inventory and survey but resources may be allocated more efficiently. For example, if formal Identification is not required, resources may be concentrated on replication and increasing sample sizes. Taxonomic minimalism may also facilitate the inclusion in these activities of important but neglected groups, especially among the invertebrates, and perhaps even microorganisms. Copyright © 1994. Published by Elsevier Ltd.

  15. 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...

  16. 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,…

  17. X-ray CT high-density artefact suppression in the presence of bones

    Energy Technology Data Exchange (ETDEWEB)

    Wei Jikun [School of Health Sciences, 550 Stadium Mall Drive, West Lafayette, IN 47907-2051 (United States); Chen Laigao [BioImaging Center of Emphasis, Pfizer Global Research and Development, 2800 Plymouth RD, Ann Arbor, MI 48105 (United States); Sandison, George A [School of Health Sciences, 550 Stadium Mall Drive, West Lafayette, IN 47907-2051 (United States); Liang Yun [Department of Radiology, Indiana University Medical School, Indianapolis, IN 46202 (United States); Xu, Lisa X [School of Mechanical Engineering, 585 Purdue Mall, West Lafayette, IN 47907-2040 (United States)

    2004-12-21

    This paper presents a novel method of reducing x-ray CT high-density artefacts generated by metal objects when abundant bone structures are present in the region of interest. This method has an advantage over previously proposed methods since it heavily suppresses the metal artefacts without introducing extra bone artefacts. The method of suppression requires that bone pixels are isolated and segmented by thresholding. Then artificial CT numbers are assigned to the bone pixels so that their projection profiles are smooth and thus can be properly simulated by a polynomial interpolation. The projection profile of the metal object is then removed to fully suppress the artefacts. The resulting processed profile is fed to a reconstruction routine and the previously preserved bone pixels added back. The new method utilizes two important features of the CT image with metal artefacts: (a) metal and bone pixels are not severely affected by the high-density artefacts and (b) the high-density artefacts can be located in specific projection channels in the profile domain, although they are spread out in the image domain. This suppression method solves the problem of CT image artefacts arising from metal objects in the body. It has the potential to greatly improve diagnostic CT imaging in the presence of these objects and treatment planning that utilizes CT for patients with metal applicators (e.g., brachytherapy for cervix cancer and prostate cryotherapy)

  18. 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,

  19. X-ray CT high-density artefact suppression in the presence of bones

    International Nuclear Information System (INIS)

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

    2004-01-01

    This paper presents a novel method of reducing x-ray CT high-density artefacts generated by metal objects when abundant bone structures are present in the region of interest. This method has an advantage over previously proposed methods since it heavily suppresses the metal artefacts without introducing extra bone artefacts. The method of suppression requires that bone pixels are isolated and segmented by thresholding. Then artificial CT numbers are assigned to the bone pixels so that their projection profiles are smooth and thus can be properly simulated by a polynomial interpolation. The projection profile of the metal object is then removed to fully suppress the artefacts. The resulting processed profile is fed to a reconstruction routine and the previously preserved bone pixels added back. The new method utilizes two important features of the CT image with metal artefacts: (a) metal and bone pixels are not severely affected by the high-density artefacts and (b) the high-density artefacts can be located in specific projection channels in the profile domain, although they are spread out in the image domain. This suppression method solves the problem of CT image artefacts arising from metal objects in the body. It has the potential to greatly improve diagnostic CT imaging in the presence of these objects and treatment planning that utilizes CT for patients with metal applicators (e.g., brachytherapy for cervix cancer and prostate cryotherapy)

  20. 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.

  1. 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.)

  2. 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.)

  3. 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

  4. 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

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. Normalization with Corresponding Naïve Tissue Minimizes Bias Caused by Commercial Reverse Transcription Kits on Quantitative Real-Time PCR Results.

    Directory of Open Access Journals (Sweden)

    Andreas Garcia-Bardon

    Full Text Available Real-time reverse transcription polymerase chain reaction (PCR is the gold standard for expression analysis. Designed to improve reproducibility and sensitivity, commercial kits are commonly used for the critical step of cDNA synthesis. The present study was designed to determine the impact of these kits. mRNA from mouse brains were pooled to create serial dilutions ranging from 0.0625 μg to 2 μg, which were transcribed into cDNA using four different commercial reverse-transcription kits. Next, we transcribed mRNA from brain tissue after acute brain injury and naïve mice into cDNA for qPCR. Depending on tested genes, some kits failed to show linear results in dilution series and revealed strong variations in cDNA yield. Absolute expression data in naïve and trauma settings varied substantially between these kits. Normalization with a housekeeping gene failed to reduce kit-dependent variations, whereas normalization eliminated differences when naïve samples from the same region were used. The study shows strong evidence that choice of commercial cDNA synthesis kit has a major impact on PCR results and, consequently, on comparability between studies. Additionally, it provides a solution to overcome this limitation by normalization with data from naïve samples. This simple step helps to compare mRNA expression data between different studies and groups.

  10. 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.

  11. The effect of head size/shape, miscentering, and bowtie filter on peak patient tissue doses from modern brain perfusion 256-slice CT: How can we minimize the risk for deterministic effects?

    International Nuclear Information System (INIS)

    Perisinakis, Kostas; Seimenis, Ioannis; Tzedakis, Antonis; Papadakis, Antonios E.; Damilakis, John

    2013-01-01

    Purpose: To determine patient-specific absorbed peak doses to skin, eye lens, brain parenchyma, and cranial red bone marrow (RBM) of adult individuals subjected to low-dose brain perfusion CT studies on a 256-slice CT scanner, and investigate the effect of patient head size/shape, head position during the examination and bowtie filter used on peak tissue doses. Methods: The peak doses to eye lens, skin, brain, and RBM were measured in 106 individual-specific adult head phantoms subjected to the standard low-dose brain perfusion CT on a 256-slice CT scanner using a novel Monte Carlo simulation software dedicated for patient CT dosimetry. Peak tissue doses were compared to corresponding thresholds for induction of cataract, erythema, cerebrovascular disease, and depression of hematopoiesis, respectively. The effects of patient head size/shape, head position during acquisition and bowtie filter used on resulting peak patient tissue doses were investigated. The effect of eye-lens position in the scanned head region was also investigated. The effect of miscentering and use of narrow bowtie filter on image quality was assessed. Results: The mean peak doses to eye lens, skin, brain, and RBM were found to be 124, 120, 95, and 163 mGy, respectively. The effect of patient head size and shape on peak tissue doses was found to be minimal since maximum differences were less than 7%. Patient head miscentering and bowtie filter selection were found to have a considerable effect on peak tissue doses. The peak eye-lens dose saving achieved by elevating head by 4 cm with respect to isocenter and using a narrow wedge filter was found to approach 50%. When the eye lies outside of the primarily irradiated head region, the dose to eye lens was found to drop to less than 20% of the corresponding dose measured when the eye lens was located in the middle of the x-ray beam. Positioning head phantom off-isocenter by 4 cm and employing a narrow wedge filter results in a moderate reduction of

  12. 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

  13. 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

  14. 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.

  15. 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...

  16. 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.

  17. The establishment of an in vitro gene bank in Dianthus spiculifolius Schur and D. glacialis ssp. gelidus (Schott Nym. et Kotschy Tutin: I. The initiation of a tissue collection and the characterization of the cultures in minimal growth conditions

    Directory of Open Access Journals (Sweden)

    Mihaela Holobiuc

    2009-12-01

    Full Text Available In the last decades the plants have to cope with the warming of the climate. As a consequence of this process more than half of the plant species could become vulnerable or threatened until 2080. Romania has a high plant diversity, with endemic and endangered plant species, the measures of biodiversity conservation being necessary. The integrated approach of biodiversity conservation involves both in situ and ex situ strategies. Among ex situ methods of conservation, besides the traditional ones (including field and botanic collection and seed banks, in vitro tissues techniques offer a viable alternative. The germplasm collections can efficiently preserve the species (of economic, scientific and conservative importance, in the same time being a source of plant material for international exchanges and for reintroduction in the native habitats.The "in vitro gene banking" term refers to in vitro tissues cultures from many accessions of a target species and involves the collection of plant material from field or from native habitats, the elaboration of sterilization, micropropagation and maintaining protocols. These collections have to be maintained in optimal conditions, morphologically and genetically characterized. The aim of our work was to characterize the response of the plant material to the minimal in vitro growth protocol for medium-term cultures achievement as a prerequisite condition for an active gene bank establishment in two rare Caryophyllaceae taxa: Dianthus spiculifolius and D. glacialis ssp. gelidus. Among different factors previously tested for medium-term preservation in Dianthus genus, mannitol proved to be more efficient for minimal cultures achievement. In vitro, the cultures were evaluated concerning their growth, regenerability and enzyme activity (POX, SOD, CAT as a response to the preservation conditions in the incipient phase of the initiation of the in vitro collection. The two species considered in this study showed a

  18. 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.

  19. 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.

  20. 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

  1. Minimally Invasive Parathyroidectomy

    Directory of Open Access Journals (Sweden)

    Lee F. Starker

    2011-01-01

    Full Text Available Minimally invasive parathyroidectomy (MIP is an operative approach for the treatment of primary hyperparathyroidism (pHPT. Currently, routine use of improved preoperative localization studies, cervical block anesthesia in the conscious patient, and intraoperative parathyroid hormone analyses aid in guiding surgical therapy. MIP requires less surgical dissection causing decreased trauma to tissues, can be performed safely in the ambulatory setting, and is at least as effective as standard cervical exploration. This paper reviews advances in preoperative localization, anesthetic techniques, and intraoperative management of patients undergoing MIP for the treatment of pHPT.

  2. 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.

  3. 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

  4. 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.

  5. Sources of Artefacts in Synthetic Aperture Radar Interferometry Data Sets

    Science.gov (United States)

    Becek, K.; Borkowski, A.

    2012-07-01

    In recent years, much attention has been devoted to digital elevation models (DEMs) produced using Synthetic Aperture Radar Interferometry (InSAR). This has been triggered by the relative novelty of the InSAR method and its world-famous product—the Shuttle Radar Topography Mission (SRTM) DEM. However, much less attention, if at all, has been paid to sources of artefacts in SRTM. In this work, we focus not on the missing pixels (null pixels) due to shadows or the layover effect, but rather on outliers that were undetected by the SRTM validation process. The aim of this study is to identify some of the causes of the elevation outliers in SRTM. Such knowledge may be helpful to mitigate similar problems in future InSAR DEMs, notably the ones currently being developed from data acquired by the TanDEM-X mission. We analysed many cross-sections derived from SRTM. These cross-sections were extracted over the elevation test areas, which are available from the Global Elevation Data Testing Facility (GEDTF) whose database contains about 8,500 runways with known vertical profiles. Whenever a significant discrepancy between the known runway profile and the SRTM cross-section was detected, a visual interpretation of the high-resolution satellite image was carried out to identify the objects causing the irregularities. A distance and a bearing from the outlier to the object were recorded. Moreover, we considered the SRTM look direction parameter. A comprehensive analysis of the acquired data allows us to establish that large metallic structures, such as hangars or car parking lots, are causing the outliers. Water areas or plain wet terrains may also cause an InSAR outlier. The look direction and the depression angle of the InSAR system in relation to the suspected objects influence the magnitude of the outliers. We hope that these findings will be helpful in designing the error detection routines of future InSAR or, in fact, any microwave aerial- or space-based survey. The

  6. SOURCES OF ARTEFACTS IN SYNTHETIC APERTURE RADAR INTERFEROMETRY DATA SETS

    Directory of Open Access Journals (Sweden)

    K. Becek

    2012-07-01

    Full Text Available In recent years, much attention has been devoted to digital elevation models (DEMs produced using Synthetic Aperture Radar Interferometry (InSAR. This has been triggered by the relative novelty of the InSAR method and its world-famous product—the Shuttle Radar Topography Mission (SRTM DEM. However, much less attention, if at all, has been paid to sources of artefacts in SRTM. In this work, we focus not on the missing pixels (null pixels due to shadows or the layover effect, but rather on outliers that were undetected by the SRTM validation process. The aim of this study is to identify some of the causes of the elevation outliers in SRTM. Such knowledge may be helpful to mitigate similar problems in future InSAR DEMs, notably the ones currently being developed from data acquired by the TanDEM-X mission. We analysed many cross-sections derived from SRTM. These cross-sections were extracted over the elevation test areas, which are available from the Global Elevation Data Testing Facility (GEDTF whose database contains about 8,500 runways with known vertical profiles. Whenever a significant discrepancy between the known runway profile and the SRTM cross-section was detected, a visual interpretation of the high-resolution satellite image was carried out to identify the objects causing the irregularities. A distance and a bearing from the outlier to the object were recorded. Moreover, we considered the SRTM look direction parameter. A comprehensive analysis of the acquired data allows us to establish that large metallic structures, such as hangars or car parking lots, are causing the outliers. Water areas or plain wet terrains may also cause an InSAR outlier. The look direction and the depression angle of the InSAR system in relation to the suspected objects influence the magnitude of the outliers. We hope that these findings will be helpful in designing the error detection routines of future InSAR or, in fact, any microwave aerial- or space

  7. 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.

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. 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)

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

    Directory of Open Access Journals (Sweden)

    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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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...

  1. 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.

  2. Sources of attenuation-correction artefacts in cardiac PET/CT and SPECT/CT.

    Science.gov (United States)

    McQuaid, Sarah J; Hutton, Brian F

    2008-06-01

    Respiratory motion during myocardial perfusion imaging can cause artefacts in both positron emission tomography (PET) and single-photon emission computed tomography (SPECT) images when mismatches between emission and transmission datasets arise. In this study, artefacts from different breathing motions were quantified in both modalities to assess key factors in attenuation-correction accuracy. Activity maps were generated using the NURBS-based cardiac-torso phantom for different respiratory cycles, which were projected, attenuation-corrected and reconstructed to form PET and SPECT images. Attenuation-correction was performed with maps at mismatched respiratory phases to observe the effect on the left-ventricular myocardium. Myocardial non-uniformity was assessed in terms of the standard deviation in scores obtained from the 17-segment model and changes in uniformity were compared for each mismatch and modality. Certain types of mismatch led to artefacts and corresponding increases in the myocardial non-uniformity. For each mismatch in PET, the increases in non-uniformity relative to an artefact-free image were as follows: (a) cardiac translation mismatch, 84% +/- 11%; (b) liver mismatch, 59% +/- 10%, (c) lung mismatch from diaphragm contraction, 28% +/- 8%; and (d) lung mismatch from chest-wall motion, 6% +/- 7%. The corresponding factors for SPECT were (a) 61% +/- 8%, (b) 34% +/- 8%, (c) -2% +/- 7)% and (d) -4% +/- 6%. Attenuation-correction artefacts were seen in PET and SPECT images, with PET being more severely affected. The most severe artefacts were produced from mismatches in cardiac and liver position, whereas lung mismatches were less critical. Both cardiac and liver positions must, therefore, be correctly matched during attenuation correction.

  3. Minimal abdominal incisions

    Directory of Open Access Journals (Sweden)

    João Carlos Magi

    2017-04-01

    Full Text Available Minimally invasive procedures aim to resolve the disease with minimal trauma to the body, resulting in a rapid return to activities and in reductions of infection, complications, costs and pain. Minimally incised laparotomy, sometimes referred to as minilaparotomy, is an example of such minimally invasive procedures. The aim of this study is to demonstrate the feasibility and utility of laparotomy with minimal incision based on the literature and exemplifying with a case. The case in question describes reconstruction of the intestinal transit with the use of this incision. Male, young, HIV-positive patient in a late postoperative of ileotiflectomy, terminal ileostomy and closing of the ascending colon by an acute perforating abdomen, due to ileocolonic tuberculosis. The barium enema showed a proximal stump of the right colon near the ileostomy. The access to the cavity was made through the orifice resulting from the release of the stoma, with a lateral-lateral ileo-colonic anastomosis with a 25 mm circular stapler and manual closure of the ileal stump. These surgeries require their own tactics, such as rigor in the lysis of adhesions, tissue traction, and hemostasis, in addition to requiring surgeon dexterity – but without the need for investments in technology; moreover, the learning curve is reported as being lower than that for videolaparoscopy. Laparotomy with minimal incision should be considered as a valid and viable option in the treatment of surgical conditions. Resumo: Procedimentos minimamente invasivos visam resolver a doença com o mínimo de trauma ao organismo, resultando em retorno rápido às atividades, reduções nas infecções, complicações, custos e na dor. A laparotomia com incisão mínima, algumas vezes referida como minilaparotomia, é um exemplo desses procedimentos minimamente invasivos. O objetivo deste trabalho é demonstrar a viabilidade e utilidade das laparotomias com incisão mínima com base na literatura e

  4. 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.

  5. 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.

  6. 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

  7. The minimally tuned minimal supersymmetric standard model

    International Nuclear Information System (INIS)

    Essig, Rouven; Fortin, Jean-Francois

    2008-01-01

    The regions in the Minimal Supersymmetric Standard Model with the minimal amount of fine-tuning of electroweak symmetry breaking are presented for general messenger scale. No a priori relations among the soft supersymmetry breaking parameters are assumed and fine-tuning is minimized with respect to all the important parameters which affect electroweak symmetry breaking. The superpartner spectra in the minimally tuned region of parameter space are quite distinctive with large stop mixing at the low scale and negative squark soft masses at the high scale. The minimal amount of tuning increases enormously for a Higgs mass beyond roughly 120 GeV

  8. 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.)

  9. 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.

  10. 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.)

  11. An investigation of inconsistent projections and artefacts in multi-pinhole SPECT with axially aligned pinholes

    International Nuclear Information System (INIS)

    Kench, P L; Meikle, S R; Lin, J; Gregoire, M C

    2011-01-01

    Multiple pinholes are advantageous for maximizing the use of the available field of view (FOV) of compact small animal single photon emission computed tomography (SPECT) detectors. However, when the pinholes are aligned axially to optimize imaging of extended objects, such as rodents, multiplexing of the pinhole projections can give rise to inconsistent data which leads to 'ghost point' artefacts in the reconstructed volume. A novel four pinhole collimator with a baffle was designed and implemented to eliminate these inconsistent projections. Simulation and physical phantom studies were performed to investigate artefacts from axially aligned pinholes and the efficacy of the baffle in removing inconsistent data and, thus, reducing reconstruction artefacts. SPECT was performed using a Defrise phantom to investigate the impact of collimator design on FOV utilization and axial blurring effects. Multiple pinhole SPECT acquired with a baffle had fewer artefacts and improved quantitative accuracy when compared to SPECT acquired without a baffle. The use of four pinholes positioned in a square maximized the available FOV, increased acquisition sensitivity and reduced axial blurring effects. These findings support the use of a baffle to eliminate inconsistent projection data arising from axially aligned pinholes and improve small animal SPECT reconstructions.

  12. 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…

  13. 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…

  14. 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…

  15. 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)

  16. 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)

  17. 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

  18. 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.

  19. 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.

  20. 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.)

  1. 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

  2. The minimal non-minimal standard model

    International Nuclear Information System (INIS)

    Bij, J.J. van der

    2006-01-01

    In this Letter I discuss a class of extensions of the standard model that have a minimal number of possible parameters, but can in principle explain dark matter and inflation. It is pointed out that the so-called new minimal standard model contains a large number of parameters that can be put to zero, without affecting the renormalizability of the model. With the extra restrictions one might call it the minimal (new) non-minimal standard model (MNMSM). A few hidden discrete variables are present. It is argued that the inflaton should be higher-dimensional. Experimental consequences for the LHC and the ILC are discussed

  3. 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

  4. 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)

  5. Minimally processed fruit salad enriched with Lactobacillus ...

    African Journals Online (AJOL)

    paula

    2015-06-17

    Jun 17, 2015 ... Minimal processing promotes browning of some vegetal tissues due to cell membrane disruption, which results in the release of oxidative enzymes. This study evaluated the efficiency of citric acid, ascorbic acid, sodium metabisulfite and L-cysteine hydrochloride to retard enzymatic browning of minimally.

  6. Minimally processed fruit salad enriched with Lactobacillus ...

    African Journals Online (AJOL)

    Minimal processing promotes browning of some vegetal tissues due to cell membrane disruption, which results in the release of oxidative enzymes. This study evaluated the efficiency of citric acid, ascorbic acid, sodium metabisulfite and L-cysteine hydrochloride to retard enzymatic browning of minimally processed fruit ...

  7. Reduction of the pace polarization artefact for capture detection applications by a tri-phasic stimulation pulse.

    Science.gov (United States)

    Sutton, R; Fröhlig, G; de Voogt, W G; Goethals, M; Hintringer, F; Kennergren, C; Scanu, P; Guilleman, D; Treese, N; Hartung, W M; Stammwitz, E; Muetstege, A

    2004-11-01

    This study investigated the ability to minimize pace polarization artefacts (PPA) by adjusting the post-stimulus pulse duration of a tri-phasic stimulation pulse. Adjustment of the stimulation pulse was enabled by downloading special study software into an already implanted pacemaker. Tests were performed in a total of 296 atrial leads and 311 ventricular leads. Both chronic and acute leads were included in the study. Statistically significant differences were found in the initial PPA (without any adjustment of the stimulus pulse) between atrial and ventricular leads. In addition, significant differences were observed among various lead models with respect to changes over time in the initial ventricular PPA. Successful PPA reduction was defined as a reduction of the PPA below 0.5 mV for atrial leads and below 1 mV for ventricular leads. Results show a success rate for ventricular and atrial PPA reduction of 97.8% and 98.7%, respectively. Threshold tests showed that after reduction of the PPA loss of ventricular capture can be reliably detected. However, atrial threshold tests showed many false positive evoked response detections. In addition, unexpectedly high evoked response amplitudes were observed in the atrium after reduction of the PPA. Results from additional measurements suggest that these high atrial evoked response amplitudes come from the influence of the input filter of the pacemaker.

  8. 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.

  9. 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

  10. 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

  11. 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

  12. 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

  13. 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.

  14. 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

  15. The microbe-free plant: fact or artefact?

    Directory of Open Access Journals (Sweden)

    Laila P. Pamela Partida-Martinez

    2011-12-01

    Full Text Available Plant-microbe interactions are ubiquitous. Plants are often colonized by pathogens but even more commonly engaged in neutral or mutualistic interactions with microbes: below-ground microbial plant associates are mycorrhizal fungi, Rhizobia and rhizosphere bacteria, above-ground plant parts are colonized by bacterial and fungal endophytes and by microbes in the phyllosphere. We emphasize here that a completely microbe-free plant is an exotic exception rather than the biologically relevant rule. The complex interplay of such microbial communities with the host plant affects plant nutrition, growth rate, resistance to biotic and abiotic stress, and plant survival and distribution. The mechanisms involved reach from nutrient acquisition, the production of plant hormones or direct antibiosis to effects on host resistance genes or interactions at higher trophic levels. Plant-associated microbes are heterotrophic and cause costs to their host plant, whereas the benefits depend on the environment. Thus, the outcome of the interaction is highly context-dependent. Considering the microbe-free plant as the ‘normal’ or control stage significantly impairs research into important phenomena such as (1 phenotypic and epigenetic plasticity, (2 the ‘normal’ ecological outcome of a given interaction and (3 the evolution of plants. For the future, we suggest cultivation-independent screening methods using direct PCR from plant tissue of more than one fungal and bacterial gene to collect data on the true microbial diversity in wild plants. The patterns found could be correlated to host species and environmental conditions, in order to formulate testable hypotheses on the biological roles of plant endophytes in nature. Experimental approaches should compare different host-endophyte combinations under various environmental conditions and study at the genetic, transcriptional and physiological level the parameters that shift the interaction along the mutualism

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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)

  1. 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

  2. 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...

  3. 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

  4. 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.)

  5. 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...

  6. 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...

  7. 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...

  8. 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...

  9. 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...

  10. 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.

  11. 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...

  12. 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.)

  13. Transverse grooved artefacts from southwestern Asia and northern Eurasia: Common traits and the reconstruction of function

    Directory of Open Access Journals (Sweden)

    Irina Usacheva

    2016-10-01

    Full Text Available Transverse grooved artefacts (TGA appeared as a new cultural element in Mesolithic-Proto-Neolithic sites in southwestern Asia. We know of similar artefacts from northern Africa. Hundreds of TGA have also been found in northern Eurasia. Some common traits were found in specimens from far apart territories, such as the non-abrasive heat-resistant nature of the raw materials, specificity of fragmentation without any signs of physical impact, the standard size of the grooves, association with a specific type of landscape, the similar economic level of the societies with which the items are associated, and use-wear marks in the grooves. Based on these regularities we can speak of a single main function for these artefacts which support the earlier reconstruction of R.L. and R.S. Solecki, suggesting that grooved stones were used for straightening cane and reed shafts under heating. Other evidence and traces that have been identified on the surface of TGA outside the groove could be associated with a variety of additional functions.

  14. 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

  15. 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.

  16. 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.

  17. Regularity of Minimal Surfaces

    CERN Document Server

    Dierkes, Ulrich; Tromba, Anthony J; Kuster, Albrecht

    2010-01-01

    "Regularity of Minimal Surfaces" begins with a survey of minimal surfaces with free boundaries. Following this, the basic results concerning the boundary behaviour of minimal surfaces and H-surfaces with fixed or free boundaries are studied. In particular, the asymptotic expansions at interior and boundary branch points are derived, leading to general Gauss-Bonnet formulas. Furthermore, gradient estimates and asymptotic expansions for minimal surfaces with only piecewise smooth boundaries are obtained. One of the main features of free boundary value problems for minimal surfaces is t

  18. 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.)

  19. 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.

  20. 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.)

  1. 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

  2. Correlates of minimal dating.

    Science.gov (United States)

    Leck, Kira

    2006-10-01

    Researchers have associated minimal dating with numerous factors. The present author tested shyness, introversion, physical attractiveness, performance evaluation, anxiety, social skill, social self-esteem, and loneliness to determine the nature of their relationships with 2 measures of self-reported minimal dating in a sample of 175 college students. For women, shyness, introversion, physical attractiveness, self-rated anxiety, social self-esteem, and loneliness correlated with 1 or both measures of minimal dating. For men, physical attractiveness, observer-rated social skill, social self-esteem, and loneliness correlated with 1 or both measures of minimal dating. The patterns of relationships were not identical for the 2 indicators of minimal dating, indicating the possibility that minimal dating is not a single construct as researchers previously believed. The present author discussed implications and suggestions for future researchers.

  3. Hexavalent Chromium Minimization Strategy

    Science.gov (United States)

    2011-05-01

    Logistics 4 Initiative - DoD Hexavalent Chromium Minimization Non- Chrome Primer IIEXAVAJ ENT CHRO:M I~UMI CHROMIUM (VII Oil CrfVli.J CANCEfl HAnRD CD...Management Office of the Secretary of Defense Hexavalent Chromium Minimization Strategy Report Documentation Page Form ApprovedOMB No. 0704-0188...00-2011 4. TITLE AND SUBTITLE Hexavalent Chromium Minimization Strategy 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6

  4. Minimal Super Technicolor

    DEFF Research Database (Denmark)

    Antola, M.; Di Chiara, S.; Sannino, F.

    2011-01-01

    We introduce novel extensions of the Standard Model featuring a supersymmetric technicolor sector (supertechnicolor). As the first minimal conformal supertechnicolor model we consider N=4 Super Yang-Mills which breaks to N=1 via the electroweak interactions. This is a well defined, economical......, between unparticle physics and Minimal Walking Technicolor. We consider also other N =1 extensions of the Minimal Walking Technicolor model. The new models allow all the standard model matter fields to acquire a mass....

  5. Minimizing Mutual Couping

    DEFF Research Database (Denmark)

    2010-01-01

    Disclosed herein are techniques, systems, and methods relating to minimizing mutual coupling between a first antenna and a second antenna.......Disclosed herein are techniques, systems, and methods relating to minimizing mutual coupling between a first antenna and a second antenna....

  6. Ruled Laguerre minimal surfaces

    KAUST Repository

    Skopenkov, Mikhail; Pottmann, Helmut; Grohs, Philipp

    2011-01-01

    A Laguerre minimal surface is an immersed surface in ℝ 3 being an extremal of the functional ∫ (H 2/K-1)dA. In the present paper, we prove that the only ruled Laguerre minimal surfaces are up to isometry the surfaces ℝ (φλ) = (Aφ, Bφ, Cφ + D cos 2φ

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. 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...

  14. 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.

  15. 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

  16. 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.

  17. 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

  18. 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...

  19. 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.

  20. Minimizing Exposure at Work

    Science.gov (United States)

    ; Environment Human Health Animal Health Safe Use Practices Food Safety Environment Air Water Soil Wildlife Home Page Pesticide Health and Safety Information Safe Use Practices Minimizing Exposure at Work Pesticides - Pennsylvania State University Cooperative Extension Personal Protective Equipment for Working

  1. Minimalism. Clip and Save.

    Science.gov (United States)

    Hubbard, Guy

    2002-01-01

    Provides background information on the art movement called "Minimalism" discussing why it started and its characteristics. Includes learning activities and information on the artist, Donald Judd. Includes a reproduction of one of his art works and discusses its content. (CMK)

  2. Ruled Laguerre minimal surfaces

    KAUST Repository

    Skopenkov, Mikhail

    2011-10-30

    A Laguerre minimal surface is an immersed surface in ℝ 3 being an extremal of the functional ∫ (H 2/K-1)dA. In the present paper, we prove that the only ruled Laguerre minimal surfaces are up to isometry the surfaces ℝ (φλ) = (Aφ, Bφ, Cφ + D cos 2φ) + λ(sin φ, cos φ, 0), where A,B,C,D ε ℝ are fixed. To achieve invariance under Laguerre transformations, we also derive all Laguerre minimal surfaces that are enveloped by a family of cones. The methodology is based on the isotropic model of Laguerre geometry. In this model a Laguerre minimal surface enveloped by a family of cones corresponds to a graph of a biharmonic function carrying a family of isotropic circles. We classify such functions by showing that the top view of the family of circles is a pencil. © 2011 Springer-Verlag.

  3. 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)

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. Minimal and careful processing

    OpenAIRE

    Nielsen, Thorkild

    2004-01-01

    In several standards, guidelines and publications, organic food processing is strongly associated with "minimal processing" and "careful processing". The term "minimal processing" is nowadays often used in the general food processing industry and described in literature. The term "careful processing" is used more specifically within organic food processing but is not yet clearly defined. The concept of carefulness seems to fit very well with the processing of organic foods, especially if it i...

  12. 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

  13. 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)

  14. 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

  15. A Single Bout of Fasting (24 h) Reduces Basal Cytokine Expression and Minimally Impacts the Sterile Inflammatory Response in the White Adipose Tissue of Normal Weight F344 Rats.

    Science.gov (United States)

    Speaker, Kristin J; Paton, Madeline M; Cox, Stewart S; Fleshner, Monika

    2016-01-01

    Sterile inflammation occurs when inflammatory proteins are increased in blood and tissues by nonpathogenic states and is a double-edged sword depending on its cause (stress, injury, or disease), duration (transient versus chronic), and inflammatory milieu. Short-term fasting can exert a host of health benefits through unknown mechanisms. The following experiment tested if a 24 h fast would modulate basal and stress-evoked sterile inflammation in plasma and adipose. Adult male F344 rats were either randomized to ad libitum access to food or fasted for 24 h prior to 0 (control), 10, or 100, 1.5 mA-5 s intermittent, inescapable tail shocks (IS). Glucose, nonesterified free fatty acids (NEFAs), insulin, leptin, and corticosterone were measured in plasma and tumor necrosis factor- (TNF-) α , interleukin- (IL-) 1 β , IL-6, and IL-10 in plasma, and subcutaneous, intraperitoneal, and visceral compartments of white adipose tissue (WAT). In control rats, a 24 h fast reduced all measured basal cytokines in plasma and visceral WAT, IL-1 β and IL-6 in subcutaneous WAT, and IL-6 in intraperitoneal WAT. In stressed rats (IS), fasting reduced visceral WAT TNF- α , subcutaneous WAT IL-1 β , and plasma insulin and leptin. Short-term fasting may thus prove to be a useful dietary strategy for reducing peripheral inflammatory states associated with visceral obesity and chronic stress.

  16. A Single Bout of Fasting (24 h Reduces Basal Cytokine Expression and Minimally Impacts the Sterile Inflammatory Response in the White Adipose Tissue of Normal Weight F344 Rats

    Directory of Open Access Journals (Sweden)

    Kristin J. Speaker

    2016-01-01

    Full Text Available Sterile inflammation occurs when inflammatory proteins are increased in blood and tissues by nonpathogenic states and is a double-edged sword depending on its cause (stress, injury, or disease, duration (transient versus chronic, and inflammatory milieu. Short-term fasting can exert a host of health benefits through unknown mechanisms. The following experiment tested if a 24 h fast would modulate basal and stress-evoked sterile inflammation in plasma and adipose. Adult male F344 rats were either randomized to ad libitum access to food or fasted for 24 h prior to 0 (control, 10, or 100, 1.5 mA-5 s intermittent, inescapable tail shocks (IS. Glucose, nonesterified free fatty acids (NEFAs, insulin, leptin, and corticosterone were measured in plasma and tumor necrosis factor- (TNF- α, interleukin- (IL- 1β, IL-6, and IL-10 in plasma, and subcutaneous, intraperitoneal, and visceral compartments of white adipose tissue (WAT. In control rats, a 24 h fast reduced all measured basal cytokines in plasma and visceral WAT, IL-1β and IL-6 in subcutaneous WAT, and IL-6 in intraperitoneal WAT. In stressed rats (IS, fasting reduced visceral WAT TNF-α, subcutaneous WAT IL-1β, and plasma insulin and leptin. Short-term fasting may thus prove to be a useful dietary strategy for reducing peripheral inflammatory states associated with visceral obesity and chronic stress.

  17. Waste minimization assessment procedure

    International Nuclear Information System (INIS)

    Kellythorne, L.L.

    1993-01-01

    Perry Nuclear Power Plant began developing a waste minimization plan early in 1991. In March of 1991 the plan was documented following a similar format to that described in the EPA Waste Minimization Opportunity Assessment Manual. Initial implementation involved obtaining management's commitment to support a waste minimization effort. The primary assessment goal was to identify all hazardous waste streams and to evaluate those streams for minimization opportunities. As implementation of the plan proceeded, non-hazardous waste streams routinely generated in large volumes were also evaluated for minimization opportunities. The next step included collection of process and facility data which would be useful in helping the facility accomplish its assessment goals. This paper describes the resources that were used and which were most valuable in identifying both the hazardous and non-hazardous waste streams that existed on site. For each material identified as a waste stream, additional information regarding the materials use, manufacturer, EPA hazardous waste number and DOT hazard class was also gathered. Once waste streams were evaluated for potential source reduction, recycling, re-use, re-sale, or burning for heat recovery, with disposal as the last viable alternative

  18. 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

  19. Minimal quantization and confinement

    International Nuclear Information System (INIS)

    Ilieva, N.P.; Kalinowskij, Yu.L.; Nguyen Suan Han; Pervushin, V.N.

    1987-01-01

    A ''minimal'' version of the Hamiltonian quantization based on the explicit solution of the Gauss equation and on the gauge-invariance principle is considered. By the example of the one-particle Green function we show that the requirement for gauge invariance leads to relativistic covariance of the theory and to more proper definition of the Faddeev - Popov integral that does not depend on the gauge choice. The ''minimal'' quantization is applied to consider the gauge-ambiguity problem and a new topological mechanism of confinement

  20. Minimal Composite Inflation

    DEFF Research Database (Denmark)

    Channuie, Phongpichit; Jark Joergensen, Jakob; Sannino, Francesco

    2011-01-01

    We investigate models in which the inflaton emerges as a composite field of a four dimensional, strongly interacting and nonsupersymmetric gauge theory featuring purely fermionic matter. We show that it is possible to obtain successful inflation via non-minimal coupling to gravity, and that the u......We investigate models in which the inflaton emerges as a composite field of a four dimensional, strongly interacting and nonsupersymmetric gauge theory featuring purely fermionic matter. We show that it is possible to obtain successful inflation via non-minimal coupling to gravity...

  1. Minimalism and Speakers’ Intuitions

    Directory of Open Access Journals (Sweden)

    Matías Gariazzo

    2011-08-01

    Full Text Available Minimalism proposes a semantics that does not account for speakers’ intuitions about the truth conditions of a range of sentences or utterances. Thus, a challenge for this view is to offer an explanation of how its assignment of semantic contents to these sentences is grounded in their use. Such an account was mainly offered by Soames, but also suggested by Cappelen and Lepore. The article criticizes this explanation by presenting four kinds of counterexamples to it, and arrives at the conclusion that minimalism has not successfully answered the above-mentioned challenge.

  2. Minimal open strings

    International Nuclear Information System (INIS)

    Hosomichi, Kazuo

    2008-01-01

    We study FZZT-branes and open string amplitudes in (p, q) minimal string theory. We focus on the simplest boundary changing operators in two-matrix models, and identify the corresponding operators in worldsheet theory through the comparison of amplitudes. Along the way, we find a novel linear relation among FZZT boundary states in minimal string theory. We also show that the boundary ground ring is realized on physical open string operators in a very simple manner, and discuss its use for perturbative computation of higher open string amplitudes.

  3. 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)

  4. 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.

  5. 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

  6. 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.

  7. 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)

  8. Minimal model holography

    International Nuclear Information System (INIS)

    Gaberdiel, Matthias R; Gopakumar, Rajesh

    2013-01-01

    We review the duality relating 2D W N minimal model conformal field theories, in a large-N ’t Hooft like limit, to higher spin gravitational theories on AdS 3 . This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘Higher spin theories and holography’. (review)

  9. Minimal constrained supergravity

    Energy Technology Data Exchange (ETDEWEB)

    Cribiori, N. [Dipartimento di Fisica e Astronomia “Galileo Galilei”, Università di Padova, Via Marzolo 8, 35131 Padova (Italy); INFN, Sezione di Padova, Via Marzolo 8, 35131 Padova (Italy); Dall' Agata, G., E-mail: dallagat@pd.infn.it [Dipartimento di Fisica e Astronomia “Galileo Galilei”, Università di Padova, Via Marzolo 8, 35131 Padova (Italy); INFN, Sezione di Padova, Via Marzolo 8, 35131 Padova (Italy); Farakos, F. [Dipartimento di Fisica e Astronomia “Galileo Galilei”, Università di Padova, Via Marzolo 8, 35131 Padova (Italy); INFN, Sezione di Padova, Via Marzolo 8, 35131 Padova (Italy); Porrati, M. [Center for Cosmology and Particle Physics, Department of Physics, New York University, 4 Washington Place, New York, NY 10003 (United States)

    2017-01-10

    We describe minimal supergravity models where supersymmetry is non-linearly realized via constrained superfields. We show that the resulting actions differ from the so called “de Sitter” supergravities because we consider constraints eliminating directly the auxiliary fields of the gravity multiplet.

  10. Hazardous waste minimization

    International Nuclear Information System (INIS)

    Freeman, H.

    1990-01-01

    This book presents an overview of waste minimization. Covers applications of technology to waste reduction, techniques for implementing programs, incorporation of programs into R and D, strategies for private industry and the public sector, and case studies of programs already in effect

  11. Minimally invasive distal pancreatectomy

    NARCIS (Netherlands)

    Røsok, Bård I.; de Rooij, Thijs; van Hilst, Jony; Diener, Markus K.; Allen, Peter J.; Vollmer, Charles M.; Kooby, David A.; Shrikhande, Shailesh V.; Asbun, Horacio J.; Barkun, Jeffrey; Besselink, Marc G.; Boggi, Ugo; Conlon, Kevin; Han, Ho Seong; Hansen, Paul; Kendrick, Michael L.; Kooby, David; Montagnini, Andre L.; Palanivelu, Chinnasamy; Wakabayashi, Go; Zeh, Herbert J.

    2017-01-01

    The first International conference on Minimally Invasive Pancreas Resection was arranged in conjunction with the annual meeting of the International Hepato-Pancreato-Biliary Association (IHPBA), in Sao Paulo, Brazil on April 19th 2016. The presented evidence and outcomes resulting from the session

  12. Minimal DBM Substraction

    DEFF Research Database (Denmark)

    David, Alexandre; Håkansson, John; G. Larsen, Kim

    In this paper we present an algorithm to compute DBM substractions with a guaranteed minimal number of splits and disjoint DBMs to avoid any redundance. The substraction is one of the few operations that result in a non-convex zone, and thus, requires splitting. It is of prime importance to reduce...

  13. Minimal constrained supergravity

    Directory of Open Access Journals (Sweden)

    N. Cribiori

    2017-01-01

    Full Text Available We describe minimal supergravity models where supersymmetry is non-linearly realized via constrained superfields. We show that the resulting actions differ from the so called “de Sitter” supergravities because we consider constraints eliminating directly the auxiliary fields of the gravity multiplet.

  14. Minimal constrained supergravity

    International Nuclear Information System (INIS)

    Cribiori, N.; Dall'Agata, G.; Farakos, F.; Porrati, M.

    2017-01-01

    We describe minimal supergravity models where supersymmetry is non-linearly realized via constrained superfields. We show that the resulting actions differ from the so called “de Sitter” supergravities because we consider constraints eliminating directly the auxiliary fields of the gravity multiplet.

  15. 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.

  16. 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.

  17. 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

  18. 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...

  19. 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.

  20. 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

  1. 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

  2. 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

  3. 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.

  4. 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...

  5. 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.

  6. Minimal Walking Technicolor

    DEFF Research Database (Denmark)

    Foadi, Roshan; Frandsen, Mads Toudal; A. Ryttov, T.

    2007-01-01

    Different theoretical and phenomenological aspects of the Minimal and Nonminimal Walking Technicolor theories have recently been studied. The goal here is to make the models ready for collider phenomenology. We do this by constructing the low energy effective theory containing scalars......, pseudoscalars, vector mesons and other fields predicted by the minimal walking theory. We construct their self-interactions and interactions with standard model fields. Using the Weinberg sum rules, opportunely modified to take into account the walking behavior of the underlying gauge theory, we find...... interesting relations for the spin-one spectrum. We derive the electroweak parameters using the newly constructed effective theory and compare the results with the underlying gauge theory. Our analysis is sufficiently general such that the resulting model can be used to represent a generic walking technicolor...

  7. 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

  8. 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

  9. Legal incentives for minimizing waste

    International Nuclear Information System (INIS)

    Clearwater, S.W.; Scanlon, J.M.

    1991-01-01

    Waste minimization, or pollution prevention, has become an integral component of federal and state environmental regulation. Minimizing waste offers many economic and public relations benefits. In addition, waste minimization efforts can also dramatically reduce potential criminal requirements. This paper addresses the legal incentives for minimizing waste under current and proposed environmental laws and regulations

  10. DNA from keratinous tissue

    DEFF Research Database (Denmark)

    Bengtsson, Camilla F.; Olsen, Maja E.; Brandt, Luise Ørsted

    2011-01-01

    Keratinous tissues such as nail, hair, horn, scales and feather have been used as a source of DNA for over 20 years. Particular benefits of such tissues include the ease with which they can be sampled, the relative stability of DNA in such tissues once sampled, and, in the context of ancient...... genetic analyses, the fact that sampling generally causes minimal visual damage to valuable specimens. Even when freshly sampled, however, the DNA quantity and quality in the fully keratinized parts of such tissues is extremely poor in comparison to other tissues such as blood and muscle – although little...... systematic research has been undertaken to characterize how such degradation may relate to sample source. In this review paper we present the current understanding of the quality and limitations of DNA in two key keratinous tissues, nail and hair. The findings indicate that although some fragments of nuclear...

  11. 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

  12. The ZOOM minimization package

    International Nuclear Information System (INIS)

    Fischler, Mark S.; Sachs, D.

    2004-01-01

    A new object-oriented Minimization package is available for distribution in the same manner as CLHEP. This package, designed for use in HEP applications, has all the capabilities of Minuit, but is a re-write from scratch, adhering to modern C++ design principles. A primary goal of this package is extensibility in several directions, so that its capabilities can be kept fresh with as little maintenance effort as possible. This package is distinguished by the priority that was assigned to C++ design issues, and the focus on producing an extensible system that will resist becoming obsolete

  13. Minimizing the Pacman effect

    International Nuclear Information System (INIS)

    Ritson, D.; Chou, W.

    1997-10-01

    The Pacman bunches will experience two deleterious effects: tune shift and orbit displacement. It is known that the tune shift can be compensated by arranging crossing planes 900 relative to each other at successive interaction points (lPs). This paper gives an analytical estimate of the Pacman orbit displacement for a single as well as for two crossings. For the latter, it can be minimized by using equal phase advances from one IP to another. In the LHC, this displacement is in any event small and can be neglected

  14. 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.)

  15. 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).

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. 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...

  2. Registers of Artefacts of Creation—From the Late Medieval Period to the 19th Century

    Directory of Open Access Journals (Sweden)

    Chris Dent

    2014-06-01

    Full Text Available This paper offers a new perspective on the “development” of the intellectual property regimes in the United Kingdom. The system put in place under the 1875 Trade Marks Act may be seen as the last of a sequence of earlier “technologies” that sought to administer the creative endeavours of (sections of the English population. Prior to the trade mark registration (that included examination there was the registration of designs that did not require examination but was necessary for the protection of the right. In the eighteenth century, patent specifications were lodged with the Crown via a process that was much more involved than that was instituted for designs in the nineteenth century. Before that, books had to be enrolled with the Stationers’ Company before they could be printed. And, in what may be seen as an earlier attempt at the centralised regulation of artefacts of expression, the Rolls of Arms (maintained by the King of Arms was repository of coats of arms for English nobility. An exploration of these different technologies of regulation, in their socio-political context, will offer new insight into the antecedents, and limits, of the registration systems that are now common across the intellectual property world.

  3. Wet-chemical etching of atom probe tips for artefact free analyses of nanoscaled semiconductor structures.

    Science.gov (United States)

    Melkonyan, D; Fleischmann, C; Veloso, A; Franquet, A; Bogdanowicz, J; Morris, R J H; Vandervorst, W

    2018-03-01

    We introduce an innovative specimen preparation method employing the selectivity of a wet-chemical etching step to improve data quality and success rates in the atom probe analysis of contemporary semiconductor devices. Firstly, on the example of an SiGe fin embedded in SiO 2 we demonstrate how the selective removal of SiO 2 from the final APT specimen significantly improves accuracy and reliability of the reconstructed data. With the oxide removal, we eliminate the origin of shape artefacts, i.e. the formation of a non-hemispherical tip shape, that are typically observed in the reconstructed volume of complex systems. Secondly, using the same approach, we increase success rates to ∼90% for the damage-free, 3D site-specific localization of short (250 nm), vertical Si nanowires at the specimen apex. The impact of the abrupt emitter radius change that is introduced by this specimen preparation method is evaluated as being minor using field evaporation simulation and comparison of different reconstruction schemes. The Ge content within the SiGe fin as well as the 3D boron distribution in the Si NW as resolved by atom probe analysis are in good agreement with TEM/EDS and ToF-SIMS analysis, respectively. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. 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.

  5. Minimal conformal model

    Energy Technology Data Exchange (ETDEWEB)

    Helmboldt, Alexander; Humbert, Pascal; Lindner, Manfred; Smirnov, Juri [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany)

    2016-07-01

    The gauge hierarchy problem is one of the crucial drawbacks of the standard model of particle physics (SM) and thus has triggered model building over the last decades. Its most famous solution is the introduction of low-scale supersymmetry. However, without any significant signs of supersymmetric particles at the LHC to date, it makes sense to devise alternative mechanisms to remedy the hierarchy problem. One such mechanism is based on classically scale-invariant extensions of the SM, in which both the electroweak symmetry and the (anomalous) scale symmetry are broken radiatively via the Coleman-Weinberg mechanism. Apart from giving an introduction to classically scale-invariant models, the talk presents our results on obtaining a theoretically consistent minimal extension of the SM, which reproduces the correct low-scale phenomenology.

  6. Minimal Reducts with Grasp

    Directory of Open Access Journals (Sweden)

    Iris Iddaly Mendez Gurrola

    2011-03-01

    Full Text Available The proper detection of patient level of dementia is important to offer the suitable treatment. The diagnosis is based on certain criteria, reflected in the clinical examinations. From these examinations emerge the limitations and the degree in which each patient is in. In order to reduce the total of limitations to be evaluated, we used the rough set theory, this theory has been applied in areas of the artificial intelligence such as decision analysis, expert systems, knowledge discovery, classification with multiple attributes. In our case this theory is applied to find the minimal limitations set or reduct that generate the same classification that considering all the limitations, to fulfill this purpose we development an algorithm GRASP (Greedy Randomized Adaptive Search Procedure.

  7. Minimally extended SILH

    International Nuclear Information System (INIS)

    Chala, Mikael; Grojean, Christophe; Humboldt-Univ. Berlin; Lima, Leonardo de; Univ. Estadual Paulista, Sao Paulo

    2017-03-01

    Higgs boson compositeness is a phenomenologically viable scenario addressing the hierarchy problem. In minimal models, the Higgs boson is the only degree of freedom of the strong sector below the strong interaction scale. We present here the simplest extension of such a framework with an additional composite spin-zero singlet. To this end, we adopt an effective field theory approach and develop a set of rules to estimate the size of the various operator coefficients, relating them to the parameters of the strong sector and its structural features. As a result, we obtain the patterns of new interactions affecting both the new singlet and the Higgs boson's physics. We identify the characteristics of the singlet field which cause its effects on Higgs physics to dominate over the ones inherited from the composite nature of the Higgs boson. Our effective field theory construction is supported by comparisons with explicit UV models.

  8. Minimally extended SILH

    Energy Technology Data Exchange (ETDEWEB)

    Chala, Mikael [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Valencia Univ. (Spain). Dept. de Fisica Teorica y IFIC; Durieux, Gauthier; Matsedonskyi, Oleksii [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Grojean, Christophe [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Humboldt-Univ. Berlin (Germany). Inst. fuer Physik; Lima, Leonardo de [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Univ. Estadual Paulista, Sao Paulo (Brazil). Inst. de Fisica Teorica

    2017-03-15

    Higgs boson compositeness is a phenomenologically viable scenario addressing the hierarchy problem. In minimal models, the Higgs boson is the only degree of freedom of the strong sector below the strong interaction scale. We present here the simplest extension of such a framework with an additional composite spin-zero singlet. To this end, we adopt an effective field theory approach and develop a set of rules to estimate the size of the various operator coefficients, relating them to the parameters of the strong sector and its structural features. As a result, we obtain the patterns of new interactions affecting both the new singlet and the Higgs boson's physics. We identify the characteristics of the singlet field which cause its effects on Higgs physics to dominate over the ones inherited from the composite nature of the Higgs boson. Our effective field theory construction is supported by comparisons with explicit UV models.

  9. 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

  10. 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.

  11. 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.

  12. 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...

  13. 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.)

  14. 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.)

  15. 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.

  16. 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.)

  17. 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.)

  18. 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.)

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. Minimal Marking: A Success Story

    Science.gov (United States)

    McNeilly, Anne

    2014-01-01

    The minimal-marking project conducted in Ryerson's School of Journalism throughout 2012 and early 2013 resulted in significantly higher grammar scores in two first-year classes of minimally marked university students when compared to two traditionally marked classes. The "minimal-marking" concept (Haswell, 1983), which requires…

  4. Swarm robotics and minimalism

    Science.gov (United States)

    Sharkey, Amanda J. C.

    2007-09-01

    Swarm Robotics (SR) is closely related to Swarm Intelligence, and both were initially inspired by studies of social insects. Their guiding principles are based on their biological inspiration and take the form of an emphasis on decentralized local control and communication. Earlier studies went a step further in emphasizing the use of simple reactive robots that only communicate indirectly through the environment. More recently SR studies have moved beyond these constraints to explore the use of non-reactive robots that communicate directly, and that can learn and represent their environment. There is no clear agreement in the literature about how far such extensions of the original principles could go. Should there be any limitations on the individual abilities of the robots used in SR studies? Should knowledge of the capabilities of social insects lead to constraints on the capabilities of individual robots in SR studies? There is a lack of explicit discussion of such questions, and researchers have adopted a variety of constraints for a variety of reasons. A simple taxonomy of swarm robotics is presented here with the aim of addressing and clarifying these questions. The taxonomy distinguishes subareas of SR based on the emphases and justifications for minimalism and individual simplicity.

  5. Minimal dilaton model

    Directory of Open Access Journals (Sweden)

    Oda Kin-ya

    2013-05-01

    Full Text Available Both the ATLAS and CMS experiments at the LHC have reported the observation of the particle of mass around 125 GeV which is consistent to the Standard Model (SM Higgs boson, but with an excess of events beyond the SM expectation in the diphoton decay channel at each of them. There still remains room for a logical possibility that we are not seeing the SM Higgs but something else. Here we introduce the minimal dilaton model in which the LHC signals are explained by an extra singlet scalar of the mass around 125 GeV that slightly mixes with the SM Higgs heavier than 600 GeV. When this scalar has a vacuum expectation value well beyond the electroweak scale, it can be identified as a linearly realized version of a dilaton field. Though the current experimental constraints from the Higgs search disfavors such a region, the singlet scalar model itself still provides a viable alternative to the SM Higgs in interpreting its search results.

  6. Minimal mirror twin Higgs

    Energy Technology Data Exchange (ETDEWEB)

    Barbieri, Riccardo [Institute of Theoretical Studies, ETH Zurich,CH-8092 Zurich (Switzerland); Scuola Normale Superiore,Piazza dei Cavalieri 7, 56126 Pisa (Italy); Hall, Lawrence J.; Harigaya, Keisuke [Department of Physics, University of California,Berkeley, California 94720 (United States); Theoretical Physics Group, Lawrence Berkeley National Laboratory,Berkeley, California 94720 (United States)

    2016-11-29

    In a Mirror Twin World with a maximally symmetric Higgs sector the little hierarchy of the Standard Model can be significantly mitigated, perhaps displacing the cutoff scale above the LHC reach. We show that consistency with observations requires that the Z{sub 2} parity exchanging the Standard Model with its mirror be broken in the Yukawa couplings. A minimal such effective field theory, with this sole Z{sub 2} breaking, can generate the Z{sub 2} breaking in the Higgs sector necessary for the Twin Higgs mechanism. The theory has constrained and correlated signals in Higgs decays, direct Dark Matter Detection and Dark Radiation, all within reach of foreseen experiments, over a region of parameter space where the fine-tuning for the electroweak scale is 10-50%. For dark matter, both mirror neutrons and a variety of self-interacting mirror atoms are considered. Neutrino mass signals and the effects of a possible additional Z{sub 2} breaking from the vacuum expectation values of B−L breaking fields are also discussed.

  7. Impact of metal artefacts due to EEG electrodes in brain PET/CT imaging

    International Nuclear Information System (INIS)

    Lemmens, Catherine; Nuyts, Johan; Dupont, Patrick; Montandon, Marie-Louise; Ratib, Osman; Zaidi, Habib

    2008-01-01

    The goal of this study is to investigate the impact of electroencephalogram (EEG) electrodes on the visual quality and quantification of 18 F-FDG PET images in neurological PET/CT examinations. For this purpose, the scans of 20 epilepsy patients with EEG monitoring were used. The CT data were reconstructed with filtered backprojection (FBP) and with a metal artefact reduction (MAR) algorithm. Both data sets were used for CT-based attenuation correction (AC) of the PET data. Also, a calculated AC (CALC) technique was considered. A volume of interest (VOI)-based analysis and a voxel-based quantitative analysis were performed to compare the different AC methods. Images were also evaluated visually by two observers. It was shown with simulations and phantom measurements that from the considered AC methods, the MAR-AC can be used as the reference in this setting. The visual assessment of PET images showed local hot spots outside the brain corresponding to the locations of the electrodes when using FBP-AC. In the brain, no abnormalities were observed. The quantitative analysis showed a very good correlation between PET-FBP-AC and PET-MAR-AC, with a statistically significant positive bias in the PET-FBP-AC images of about 5-7% in most brain voxels. There was also good correlation between PET-CALC-AC and PET-MAR-AC, but in the PET-CALC-AC images, regions with both a significant positive and negative bias were observed. EEG electrodes give rise to local hot spots outside the brain and a positive quantification bias in the brain. However, when diagnosis is made by mere visual assessment, the presence of EEG electrodes does not seem to alter the diagnosis. When quantification is performed, the bias becomes an issue especially when comparing brain images with and without EEG monitoring

  8. Impact of metal artefacts due to EEG electrodes in brain PET/CT imaging

    Energy Technology Data Exchange (ETDEWEB)

    Lemmens, Catherine; Nuyts, Johan; Dupont, Patrick [Department of Nuclear Medicine and Medical Imaging Center, University Hospital Gasthuisberg and Katholieke Universiteit Leuven, Leuven (Belgium); Montandon, Marie-Louise; Ratib, Osman; Zaidi, Habib [Division of Nuclear Medicine, Geneva University Hospital, CH-1211 Geneva (Switzerland)], E-mail: catherine.lemmens@uz.kuleuven.be

    2008-08-21

    The goal of this study is to investigate the impact of electroencephalogram (EEG) electrodes on the visual quality and quantification of {sup 18}F-FDG PET images in neurological PET/CT examinations. For this purpose, the scans of 20 epilepsy patients with EEG monitoring were used. The CT data were reconstructed with filtered backprojection (FBP) and with a metal artefact reduction (MAR) algorithm. Both data sets were used for CT-based attenuation correction (AC) of the PET data. Also, a calculated AC (CALC) technique was considered. A volume of interest (VOI)-based analysis and a voxel-based quantitative analysis were performed to compare the different AC methods. Images were also evaluated visually by two observers. It was shown with simulations and phantom measurements that from the considered AC methods, the MAR-AC can be used as the reference in this setting. The visual assessment of PET images showed local hot spots outside the brain corresponding to the locations of the electrodes when using FBP-AC. In the brain, no abnormalities were observed. The quantitative analysis showed a very good correlation between PET-FBP-AC and PET-MAR-AC, with a statistically significant positive bias in the PET-FBP-AC images of about 5-7% in most brain voxels. There was also good correlation between PET-CALC-AC and PET-MAR-AC, but in the PET-CALC-AC images, regions with both a significant positive and negative bias were observed. EEG electrodes give rise to local hot spots outside the brain and a positive quantification bias in the brain. However, when diagnosis is made by mere visual assessment, the presence of EEG electrodes does not seem to alter the diagnosis. When quantification is performed, the bias becomes an issue especially when comparing brain images with and without EEG monitoring.

  9. Feasibility of clinical magnetoencephalography (MEG) functional mapping in the presence of dental artefacts.

    Science.gov (United States)

    Hillebrand, A; Fazio, P; de Munck, J C; van Dijk, B W

    2013-01-01

    To evaluate the viability of MEG source reconstruction in the presence of large interference due to orthodontic material. We recorded the magnetic fields following a simple hand movement and following electrical stimulation of the median nerve (somatosensory evoked field -SEF). These two tasks were performed twice, once with and once without artificial dental artefacts. Temporal Signal Space Separation (tSSS) was applied to spatially filter the data and source reconstruction was performed according to standard procedures for pre-surgical mapping of eloquent cortex, applying dipole fitting to the SEF data and beamforming to the hand movement data. Comparing the data with braces to the data without braces, the observed distances between the activations following hand movement in the two conditions were on average 6.4 and 4.5 mm for the left and right hand, respectively, whereas the dipole localisation errors for the SEF were 4.1 and 5.4 mm, respectively. Without tSSS it was generally not possible to obtain reliable dipole fit or beamforming results when wearing braces. We confirm that tSSS is a required and effective pre-processing step for data recorded with the Elekta-MEG system. Moreover, we have shown that even the presence of large interference from orthodontic material does not significantly alter the results from dipole localisation or beamformer analysis, provided the data are spatially filtered by tSSS. State-of-the-art signal processing techniques enable the use of MEG for pre-surgical evaluation in a much larger clinical population than previously thought possible. Copyright © 2012 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  10. Pathologic evaluation of normal and perfused term placental tissue

    DEFF Research Database (Denmark)

    Maroun, Lisa Leth; Mathiesen, Line; Hedegaard, Morten

    2014-01-01

    This study reports for the 1st time the incidence and interobserver variation of morphologic findings in a series of 34 term placentas from pregnancies with normal outcome used for perfusion studies. Histologic evaluation of placental tissue is challenging, especially when it comes to defining...... "normal tissue" versus "pathologic lesions." A scoring system for registration of abnormal morphologic findings was developed. Light microscopic examination was performed independently by 2 pathologists, and interobserver variation was analyzed. Findings in normal and perfused tissue were compared...... and selected findings were tested against success parameters from the perfusions. Finally, the criteria for frequent lesions with fair to poor interobserver variation in the nonperfused tissue were revised and reanalyzed. In the perfused tissue, the perfusion artefact "trophoblastic vacuolization," which...

  11. Surgical correction of gynecomastia with minimal scarring.

    Science.gov (United States)

    Lee, Jun-Ho; Kim, Il-Kug; Kim, Tae-Gon; Kim, Yong-Ha

    2012-12-01

    Gynecomastia is a benign, excessive development of the male breast that occurs at an overall incidence of 32-36 %. The authors effectively removed peripheral fat tissues with power-assisted liposuction (PAL) and periareolar glandular tissues with a cartilage shaver in a series of patients. The small periareolar incisions were not easily recognized. Between February 2010 and April 2012, the charts of 15 patients (28 breasts) treated with PAL and a cartilage shaver were retrospectively reviewed. The mean volume of fat tissue removed with liposuction was 319 mL, and the mean volume of glandular tissue removed with the cartilage shaver was 70 mL. The mean follow-up period was 11.2 months. No infection, nipple-areola complex necrosis, nipple retraction, or saucer deformity was encountered in this series. Intraoperative bleeding occurred in one patient. Mild asymmetries developed in three patients. Use of PAL and a cartilage shaver for the treatment of gynecomastia allows for effective removal of both the fat and the glandular tissue of the breast through a minimal periareolar incision. This technique can achieve excellent aesthetic results with inconspicuous scarring. 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 .

  12. Pediatric neuro MRI. Tricks to minimize sedation

    Energy Technology Data Exchange (ETDEWEB)

    Barkovich, Matthew J.; Desikan, Rahul S. [University of California, San Francisco, Department of Radiology and Diagnostic Imaging, San Francisco, CA (United States); Xu, Duan; Barkovich, A.J. [University of California, San Francisco, Department of Radiology and Diagnostic Imaging, San Francisco, CA (United States); UCSF-Benioff Children' s Hospital, Department of Radiology, San Francisco, CA (United States); Williams, Cassandra [UCSF-Benioff Children' s Hospital, Department of Radiology, San Francisco, CA (United States)

    2018-01-15

    Magnetic resonance imaging (MRI) is the workhorse modality in pediatric neuroimaging because it provides excellent soft-tissue contrast without ionizing radiation. Until recently, studies were uninterpretable without sedation; however, given development of shorter sequences, sequences that correct for motion, and studies showing the potentially deleterious effects of sedation on immature laboratory animals, it is prudent to minimize sedation when possible. This manuscript provides basic guidelines for performing pediatric neuro MRI without sedation by both modifying technical factors to reduce scan time and noise, and using a multi-disciplinary team to coordinate imaging with the patient's biorhythms. (orig.)

  13. Global Analysis of Minimal Surfaces

    CERN Document Server

    Dierkes, Ulrich; Tromba, Anthony J

    2010-01-01

    Many properties of minimal surfaces are of a global nature, and this is already true for the results treated in the first two volumes of the treatise. Part I of the present book can be viewed as an extension of these results. For instance, the first two chapters deal with existence, regularity and uniqueness theorems for minimal surfaces with partially free boundaries. Here one of the main features is the possibility of 'edge-crawling' along free parts of the boundary. The third chapter deals with a priori estimates for minimal surfaces in higher dimensions and for minimizers of singular integ

  14. Minimal Surfaces for Hitchin Representations

    DEFF Research Database (Denmark)

    Li, Qiongling; Dai, Song

    2018-01-01

    . In this paper, we investigate the properties of immersed minimal surfaces inside symmetric space associated to a subloci of Hitchin component: $q_n$ and $q_{n-1}$ case. First, we show that the pullback metric of the minimal surface dominates a constant multiple of the hyperbolic metric in the same conformal...... class and has a strong rigidity property. Secondly, we show that the immersed minimal surface is never tangential to any flat inside the symmetric space. As a direct corollary, the pullback metric of the minimal surface is always strictly negatively curved. In the end, we find a fully decoupled system...

  15. 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.)

  16. 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.)

  17. 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

  18. Injectable biomaterials for minimally invasive orthopedic treatments.

    Science.gov (United States)

    Jayabalan, M; Shalumon, K T; Mitha, M K

    2009-06-01

    Biodegradable and injectable hydroxy terminated-poly propylene fumarate (HT-PPF) bone cement was developed. The injectable formulation consisting HT-PPF and comonomer, n-vinyl pyrrolidone, calcium phosphate filler, free radical catalyst, accelerator and radiopaque agent sets rapidly to hard mass with low exothermic temperature. The candidate bone cement attains mechanical strength more than the required compressive strength of 5 MPa and compressive modulus 50 MPa. The candidate bone cement resin elicits cell adhesion and cytoplasmic spreading of osteoblast cells. The cured bone cement does not induce intracutaneous irritation and skin sensitization. The candidate bone cement is tissue compatible without eliciting any adverse tissue reactions. The candidate bone cement is osteoconductive and inductive and allow osteointegration and bone remodeling. HT-PPF bone cement is candidate bone cement for minimally invasive radiological procedures for the treatment of bone diseases and spinal compression fractures.

  19. 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...

  20. 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...

  1. 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.

  2. 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.

  3. 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.)

  4. 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.)

  5. Guidelines for mixed waste minimization

    International Nuclear Information System (INIS)

    Owens, C.

    1992-02-01

    Currently, there is no commercial mixed waste disposal available in the United States. Storage and treatment for commercial mixed waste is limited. Host States and compacts region officials are encouraging their mixed waste generators to minimize their mixed wastes because of management limitations. This document provides a guide to mixed waste minimization

  6. Minimal changes in health status questionnaires: distinction between minimally detectable change and minimally important change

    Directory of Open Access Journals (Sweden)

    Knol Dirk L

    2006-08-01

    Full Text Available Abstract Changes in scores on health status questionnaires are difficult to interpret. Several methods to determine minimally important changes (MICs have been proposed which can broadly be divided in distribution-based and anchor-based methods. Comparisons of these methods have led to insight into essential differences between these approaches. Some authors have tried to come to a uniform measure for the MIC, such as 0.5 standard deviation and the value of one standard error of measurement (SEM. Others have emphasized the diversity of MIC values, depending on the type of anchor, the definition of minimal importance on the anchor, and characteristics of the disease under study. A closer look makes clear that some distribution-based methods have been merely focused on minimally detectable changes. For assessing minimally important changes, anchor-based methods are preferred, as they include a definition of what is minimally important. Acknowledging the distinction between minimally detectable and minimally important changes is useful, not only to avoid confusion among MIC methods, but also to gain information on two important benchmarks on the scale of a health status measurement instrument. Appreciating the distinction, it becomes possible to judge whether the minimally detectable change of a measurement instrument is sufficiently small to detect minimally important changes.

  7. Waste minimization handbook, Volume 1

    International Nuclear Information System (INIS)

    Boing, L.E.; Coffey, M.J.

    1995-12-01

    This technical guide presents various methods used by industry to minimize low-level radioactive waste (LLW) generated during decommissioning and decontamination (D and D) activities. Such activities generate significant amounts of LLW during their operations. Waste minimization refers to any measure, procedure, or technique that reduces the amount of waste generated during a specific operation or project. Preventive waste minimization techniques implemented when a project is initiated can significantly reduce waste. Techniques implemented during decontamination activities reduce the cost of decommissioning. The application of waste minimization techniques is not limited to D and D activities; it is also useful during any phase of a facility's life cycle. This compendium will be supplemented with a second volume of abstracts of hundreds of papers related to minimizing low-level nuclear waste. This second volume is expected to be released in late 1996

  8. Waste minimization handbook, Volume 1

    Energy Technology Data Exchange (ETDEWEB)

    Boing, L.E.; Coffey, M.J.

    1995-12-01

    This technical guide presents various methods used by industry to minimize low-level radioactive waste (LLW) generated during decommissioning and decontamination (D and D) activities. Such activities generate significant amounts of LLW during their operations. Waste minimization refers to any measure, procedure, or technique that reduces the amount of waste generated during a specific operation or project. Preventive waste minimization techniques implemented when a project is initiated can significantly reduce waste. Techniques implemented during decontamination activities reduce the cost of decommissioning. The application of waste minimization techniques is not limited to D and D activities; it is also useful during any phase of a facility`s life cycle. This compendium will be supplemented with a second volume of abstracts of hundreds of papers related to minimizing low-level nuclear waste. This second volume is expected to be released in late 1996.

  9. Minimal Webs in Riemannian Manifolds

    DEFF Research Database (Denmark)

    Markvorsen, Steen

    2008-01-01

    For a given combinatorial graph $G$ a {\\it geometrization} $(G, g)$ of the graph is obtained by considering each edge of the graph as a $1-$dimensional manifold with an associated metric $g$. In this paper we are concerned with {\\it minimal isometric immersions} of geometrized graphs $(G, g......)$ into Riemannian manifolds $(N^{n}, h)$. Such immersions we call {\\em{minimal webs}}. They admit a natural 'geometric' extension of the intrinsic combinatorial discrete Laplacian. The geometric Laplacian on minimal webs enjoys standard properties such as the maximum principle and the divergence theorems, which...... are of instrumental importance for the applications. We apply these properties to show that minimal webs in ambient Riemannian spaces share several analytic and geometric properties with their smooth (minimal submanifold) counterparts in such spaces. In particular we use appropriate versions of the divergence...

  10. Thymoma and minimally invasive surgical treatment

    International Nuclear Information System (INIS)

    Krajc, T.; Spalek, P.; Lucenic, M.; Benej, R.; Harustiak, S.

    2011-01-01

    The authors review the current thymoma classification schemes, diagnosis and surgical treatment options. Many minimally invasive techniques do not provide sufficient extensiveness when compared to complete sternotomy. The Zieliński technique combines transcervical, subxiphoidal and bilateral thoracoscopic approach in a hybrid procedure (MMIT, maximal minimally invasive thymectomy) based on double sternal traction, and allows for removal of the thymus gland, the thymoma and all the relevant mediastinal adipose tissue, thus adhering to principles of oncological radicality. Of the 28 patients undergoing MMIT there were 7 with myasthenia associated thymoma (MGAT) and 5 with a thymoma and no myasthenia, tumors staged Masaoka I-II. Apart from one temporary recurrent nerve palsy there were no postoperative complications. The largest thymoma measured 70 x 65 x 55 mm. Adjuvant radiotherapy was applied in 5 patients. Ectopic thymic tissue was identified in 100 % of patients with thymoma and no myasthenia and in 42.9 % of MGAT patients. Until now there were no recurrences, however, the follow-up median is very short, the longest follow-up period being 30 months. MMIT is a safe technique suitable also for Masaoka I-II thymoma patients and for some specific cases with Masaoka III stage (lung parenchyma invasion). The authors approach all the anterior mediastinal tumors with no mediastinal lymphadenopathy and no myasthenia as a potential thymoma and always attempt the MMIT procedure starting as VATS procedure on the side of tumor. (author)

  11. 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.

  12. Minimally invasive spine surgery: Hurdles to be crossed

    Directory of Open Access Journals (Sweden)

    Mahesh Bijjawara

    2014-01-01

    Full Text Available MISS as a concept is noble and all surgeons need to address and minimize the surgical morbidity for better results. However, we need to be cautions and not fall prey into accepting that minimally invasive spine surgery can be done only when certain metal access systems are used. Minimally invasive spine surgery (MISS has come a long way since the description of endoscopic discectomy in 1997 and minimally invasive TLIF (mTLIF in 2003. Today there is credible evidence (though not level-I that MISS has comparable results to open spine surgery with the advantage of early postoperative recovery and decreased blood loss and infection rates. However, apart from decreasing the muscle trauma and decreasing the muscle dissection during multilevel open spinal instrumentation, there has been little contribution to address the other morbidity parameters like operative time , blood loss , access to decompression and atraumatic neural tissue handling with the existing MISS technologies. Since all these parameters contribute to a greater degree than posterior muscle trauma for the overall surgical morbidity, we as surgeons need to introspect before we accept the concept of minimally invasive spine surgery being reduced to surgeries performed with a few tubular retractors. A spine surgeon needs to constantly improve his skills and techniques so that he can minimize blood loss, minimize traumatic neural tissue handling and minimizing operative time without compromising on the surgical goals. These measures actually contribute far more, to decrease the morbidity than approach related muscle damage alone. Minimally invasine spine surgery , though has come a long way, needs to provide technical solutions to minimize all the morbidity parameters involved in spine surgery, before it can replace most of the open spine surgeries, as in the case of laparoscopic surgery or arthroscopic surgery.

  13. Minimal Poems Written in 1979 Minimal Poems Written in 1979

    Directory of Open Access Journals (Sweden)

    Sandra Sirangelo Maggio

    2008-04-01

    Full Text Available The reading of M. van der Slice's Minimal Poems Written in 1979 (the work, actually, has no title reminded me of a book I have seen a long time ago. called Truth, which had not even a single word printed inside. In either case we have a sample of how often excentricities can prove efficient means of artistic creativity, in this new literary trend known as Minimalism. The reading of M. van der Slice's Minimal Poems Written in 1979 (the work, actually, has no title reminded me of a book I have seen a long time ago. called Truth, which had not even a single word printed inside. In either case we have a sample of how often excentricities can prove efficient means of artistic creativity, in this new literary trend known as Minimalism.

  14. 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

  15. Minimal Flavour Violation and Beyond

    CERN Document Server

    Isidori, Gino

    2012-01-01

    We review the formulation of the Minimal Flavour Violation (MFV) hypothesis in the quark sector, as well as some "variations on a theme" based on smaller flavour symmetry groups and/or less minimal breaking terms. We also review how these hypotheses can be tested in B decays and by means of other flavour-physics observables. The phenomenological consequences of MFV are discussed both in general terms, employing a general effective theory approach, and in the specific context of the Minimal Supersymmetric extension of the SM.

  16. Minimizing waste in environmental restoration

    International Nuclear Information System (INIS)

    Thuot, J.R.; Moos, L.

    1996-01-01

    Environmental restoration, decontamination and decommissioning, and facility dismantlement projects are not typically known for their waste minimization and pollution prevention efforts. Typical projects are driven by schedules and milestones with little attention given to cost or waste minimization. Conventional wisdom in these projects is that the waste already exists and cannot be reduced or minimized; however, there are significant areas where waste and cost can be reduced by careful planning and execution. Waste reduction can occur in three ways: beneficial reuse or recycling, segregation of waste types, and reducing generation of secondary waste

  17. Minimizing waste in environmental restoration

    International Nuclear Information System (INIS)

    Moos, L.; Thuot, J.R.

    1996-01-01

    Environmental restoration, decontamination and decommissioning and facility dismantelment projects are not typically known for their waste minimization and pollution prevention efforts. Typical projects are driven by schedules and milestones with little attention given to cost or waste minimization. Conventional wisdom in these projects is that the waste already exists and cannot be reduced or minimized. In fact, however, there are three significant areas where waste and cost can be reduced. Waste reduction can occur in three ways: beneficial reuse or recycling; segregation of waste types; and reducing generation of secondary waste. This paper will discuss several examples of reuse, recycle, segregation, and secondary waste reduction at ANL restoration programs

  18. Tissue engineering

    CERN Document Server

    Fisher, John P; Bronzino, Joseph D

    2007-01-01

    Increasingly viewed as the future of medicine, the field of tissue engineering is still in its infancy. As evidenced in both the scientific and popular press, there exists considerable excitement surrounding the strategy of regenerative medicine. To achieve its highest potential, a series of technological advances must be made. Putting the numerous breakthroughs made in this field into a broad context, Tissue Engineering disseminates current thinking on the development of engineered tissues. Divided into three sections, the book covers the fundamentals of tissue engineering, enabling technologies, and tissue engineering applications. It examines the properties of stem cells, primary cells, growth factors, and extracellular matrix as well as their impact on the development of tissue engineered devices. Contributions focus on those strategies typically incorporated into tissue engineered devices or utilized in their development, including scaffolds, nanocomposites, bioreactors, drug delivery systems, and gene t...

  19. Sludge minimization technologies - an overview

    Energy Technology Data Exchange (ETDEWEB)

    Oedegaard, Hallvard

    2003-07-01

    The management of wastewater sludge from wastewater treatment plants represents one of the major challenges in wastewater treatment today. The cost of the sludge treatment amounts to more that the cost of the liquid in many cases. Therefore the focus on and interest in sludge minimization is steadily increasing. In the paper an overview is given for sludge minimization (sludge mass reduction) options. It is demonstrated that sludge minimization may be a result of reduced production of sludge and/or disintegration processes that may take place both in the wastewater treatment stage and in the sludge stage. Various sludge disintegration technologies for sludge minimization are discussed, including mechanical methods (focusing on stirred ball-mill, high-pressure homogenizer, ultrasonic disintegrator), chemical methods (focusing on the use of ozone), physical methods (focusing on thermal and thermal/chemical hydrolysis) and biological methods (focusing on enzymatic processes). (author)

  20. Wilson loops in minimal surfaces

    International Nuclear Information System (INIS)

    Drukker, Nadav; Gross, David J.; Ooguri, Hirosi

    1999-01-01

    The AdS/CFT correspondence suggests that the Wilson loop of the large N gauge theory with N = 4 supersymmetry in 4 dimensions is described by a minimal surface in AdS 5 x S 5 . The authors examine various aspects of this proposal, comparing gauge theory expectations with computations of minimal surfaces. There is a distinguished class of loops, which the authors call BPS loops, whose expectation values are free from ultra-violet divergence. They formulate the loop equation for such loops. To the extent that they have checked, the minimal surface in AdS 5 x S 5 gives a solution of the equation. The authors also discuss the zig-zag symmetry of the loop operator. In the N = 4 gauge theory, they expect the zig-zag symmetry to hold when the loop does not couple the scalar fields in the supermultiplet. They will show how this is realized for the minimal surface

  1. Classical strings and minimal surfaces

    International Nuclear Information System (INIS)

    Urbantke, H.

    1986-01-01

    Real Lorentzian forms of some complex or complexified Euclidean minimal surfaces are obtained as an application of H.A. Schwarz' solution to the initial value problem or a search for surfaces admitting a group of Poincare transformations. (Author)

  2. Minimal Gromov-Witten rings

    International Nuclear Information System (INIS)

    Przyjalkowski, V V

    2008-01-01

    We construct an abstract theory of Gromov-Witten invariants of genus 0 for quantum minimal Fano varieties (a minimal class of varieties which is natural from the quantum cohomological viewpoint). Namely, we consider the minimal Gromov-Witten ring: a commutative algebra whose generators and relations are of the form used in the Gromov-Witten theory of Fano varieties (of unspecified dimension). The Gromov-Witten theory of any quantum minimal variety is a homomorphism from this ring to C. We prove an abstract reconstruction theorem which says that this ring is isomorphic to the free commutative ring generated by 'prime two-pointed invariants'. We also find solutions of the differential equation of type DN for a Fano variety of dimension N in terms of the generating series of one-pointed Gromov-Witten invariants

  3. Wilson loops and minimal surfaces

    International Nuclear Information System (INIS)

    Drukker, Nadav; Gross, David J.; Ooguri, Hirosi

    1999-01-01

    The AdS-CFT correspondence suggests that the Wilson loop of the large N gauge theory with N=4 supersymmetry in four dimensions is described by a minimal surface in AdS 5 xS 5 . We examine various aspects of this proposal, comparing gauge theory expectations with computations of minimal surfaces. There is a distinguished class of loops, which we call BPS loops, whose expectation values are free from ultraviolet divergence. We formulate the loop equation for such loops. To the extent that we have checked, the minimal surface in AdS 5 xS 5 gives a solution of the equation. We also discuss the zigzag symmetry of the loop operator. In the N=4 gauge theory, we expect the zigzag symmetry to hold when the loop does not couple the scalar fields in the supermultiplet. We will show how this is realized for the minimal surface. (c) 1999 The American Physical Society

  4. Minimal string theory is logarithmic

    International Nuclear Information System (INIS)

    Ishimoto, Yukitaka; Yamaguchi, Shun-ichi

    2005-01-01

    We study the simplest examples of minimal string theory whose worldsheet description is the unitary (p,q) minimal model coupled to two-dimensional gravity ( Liouville field theory). In the Liouville sector, we show that four-point correlation functions of 'tachyons' exhibit logarithmic singularities, and that the theory turns out to be logarithmic. The relation with Zamolodchikov's logarithmic degenerate fields is also discussed. Our result holds for generic values of (p,q)

  5. Annual Waste Minimization Summary Report

    International Nuclear Information System (INIS)

    Haworth, D.M.

    2011-01-01

    This report summarizes the waste minimization efforts undertaken by National Security TechnoIogies, LLC, for the U. S. Department of Energy, National Nuclear Security Administration Nevada Site Office (NNSA/NSO), during calendar year 2010. The NNSA/NSO Pollution Prevention Program establishes a process to reduce the volume and toxicity of waste generated by NNSA/NSO activities and ensures that proposed methods of treatment, storage, and/or disposal of waste minimize potential threats to human health and the environment.

  6. Rapid, minimally invasive adult voluntary male circumcision: A ...

    African Journals Online (AJOL)

    To compare conventional open surgical circumcision with suturing to a minimally invasive technique using a single-use-only disposable instrument (Unicirc) plus tissue adhesive. This technique completes the circumcision at the time of surgery, and requires no further visits for device removal. We hypothesised that the new ...

  7. [Minimally invasive surgical therapy of gynecomastia: liposuction and exeresis technique].

    Science.gov (United States)

    Voigt, M; Walgenbach, K J; Andree, C; Bannasch, H; Looden, Z; Stark, G B

    2001-10-01

    A number of techniques are available for the correction of gynecomastia. Nonscarring sparing methods are preferred, and the minimally invasive technique is to use liposuction for the gland and the fatty tissue exclusively. In this retrospective study we present our experience with a combination of liposuction and subsequent resection of the remaining gland. Sixty-two patients (112 breasts) were surgically treated for gynecomastia from January 1996 and September 2000. From 1996 to 1997 all patients suffering from gynecomastia grade Simon I-II were treated by the method described by Rosenberg and Stark, which is exclusively suction of the fatty and glandular tissue. In a retrospective chart study a high recurrence rate was found in these patients. Subsequently we changed our technique to liposuction of the fatty tissue followed by sharp excision of the glandular tissue through the incision made for the liposuction cannula in the submammary fold. Suction alone was not sufficient to remove the glandular tissue; the rate of recurrence after suction was 35%. When sharp resection of the glandular tissue was carried out after the liposuction the recurrence rate dropped to under 10%. In total our complication rate was 50% including minor sequelae. The most frequent complication was unacceptable scarring of the nipple-areola complex. Hypesthesia of the nipple-areola occurred in 13.4% of the patients. The combination of liposuction and resection of the glandular tissue is a minimally invasive correction that can be used in all cases of gynecomastia grade Simon I-II.

  8. Minimal but non-minimal inflation and electroweak symmetry breaking

    Energy Technology Data Exchange (ETDEWEB)

    Marzola, Luca [National Institute of Chemical Physics and Biophysics,Rävala 10, 10143 Tallinn (Estonia); Institute of Physics, University of Tartu,Ravila 14c, 50411 Tartu (Estonia); Racioppi, Antonio [National Institute of Chemical Physics and Biophysics,Rävala 10, 10143 Tallinn (Estonia)

    2016-10-07

    We consider the most minimal scale invariant extension of the standard model that allows for successful radiative electroweak symmetry breaking and inflation. The framework involves an extra scalar singlet, that plays the rôle of the inflaton, and is compatibile with current experimental bounds owing to the non-minimal coupling of the latter to gravity. This inflationary scenario predicts a very low tensor-to-scalar ratio r≈10{sup −3}, typical of Higgs-inflation models, but in contrast yields a scalar spectral index n{sub s}≃0.97 which departs from the Starobinsky limit. We briefly discuss the collider phenomenology of the framework.

  9. Tissue types (image)

    Science.gov (United States)

    ... are 4 basic types of tissue: connective tissue, epithelial tissue, muscle tissue, and nervous tissue. Connective tissue supports ... binds them together (bone, blood, and lymph tissues). Epithelial tissue provides a covering (skin, the linings of the ...

  10. 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.

  11. Pigment identification on medieval manuscripts, paintings and other artefacts by Raman microscopy: applications to the study of three German manuscripts

    Science.gov (United States)

    Burgio, Lucia; Ciomartan, Dan A.; Clark, Robin J. H.

    1997-03-01

    The identification of the pigments used to illuminate medieval manuscripts, paintings and other artefacts has received a major boost recently through perceptive studies carried out by Raman microscopy. A brief summary of the background of the technique is given. The results of studies on three illuminated German manuscripts are presented. The pigments vermilion HgS, iron oxide Fe 2O 3, azurite 2CuCO 3.Cu(OH) 2, malachite CuCo 3.Cu(OH) 2, lampblack (essentially carbon), white lead 2PbCO 3.Pb(OH) 2, lead tin yellow type I Pb 2SnO 4, and lazurite Na 8[Al 6Si 6O 24]S n (but only in admixture with Pb 2SnO 4, whereby it forms a green pigment), have been identified on these manuscripts on the basis of Raman microscopy and the results discussed.

  12. 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.

  13. 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...

  14. 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.

  15. 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...

  16. 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.)

  17. 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.)

  18. 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...

  19. Electrocautery causes more ischemic peritoneal tissue damage than ultrasonic dissection.

    NARCIS (Netherlands)

    Broek, R.P.G ten; Wilbers, J.; Goor, H. van

    2011-01-01

    BACKGROUND: Minimizing peritoneal tissue injury during abdominal surgery has the benefit of reducing postoperative inflammatory response, pain, and adhesion formation. Ultrasonic dissection seems to reduce tissue damage. This study aimed to compare electrocautery and ultrasonic dissection in terms

  20. 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.

  1. 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

  2. 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

  3. 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.

  4. 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

  5. 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

  6. 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

  7. 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.)

  8. 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

  9. 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.

  10. 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.)

  11. Minimal modification to tribimaximal mixing

    International Nuclear Information System (INIS)

    He Xiaogang; Zee, A.

    2011-01-01

    We explore some ways of minimally modifying the neutrino mixing matrix from tribimaximal, characterized by introducing at most one mixing angle and a CP violating phase thus extending our earlier work. One minimal modification, motivated to some extent by group theoretic considerations, is a simple case with the elements V α2 of the second column in the mixing matrix equal to 1/√(3). Modifications by keeping one of the columns or one of the rows unchanged from tribimaximal mixing all belong to the class of minimal modification. Some of the cases have interesting experimentally testable consequences. In particular, the T2K and MINOS collaborations have recently reported indications of a nonzero θ 13 . For the cases we consider, the new data sharply constrain the CP violating phase angle δ, with δ close to 0 (in some cases) and π disfavored.

  12. Topological gravity with minimal matter

    International Nuclear Information System (INIS)

    Li Keke

    1991-01-01

    Topological minimal matter, obtained by twisting the minimal N = 2 supeconformal field theory, is coupled to two-dimensional topological gravity. The free field formulation of the coupled system allows explicit representations of BRST charge, physical operators and their correlation functions. The contact terms of the physical operators may be evaluated by extending the argument used in a recent solution of topological gravity without matter. The consistency of the contact terms in correlation functions implies recursion relations which coincide with the Virasoro constraints derived from the multi-matrix models. Topological gravity with minimal matter thus provides the field theoretic description for the multi-matrix models of two-dimensional quantum gravity. (orig.)

  13. Minimal Marking: A Success Story

    Directory of Open Access Journals (Sweden)

    Anne McNeilly

    2014-11-01

    Full Text Available The minimal-marking project conducted in Ryerson’s School of Journalism throughout 2012 and early 2013 resulted in significantly higher grammar scores in two first-year classes of minimally marked university students when compared to two traditionally marked classes. The “minimal-marking” concept (Haswell, 1983, which requires dramatically more student engagement, resulted in more successful learning outcomes for surface-level knowledge acquisition than the more traditional approach of “teacher-corrects-all.” Results suggest it would be effective, not just for grammar, punctuation, and word usage, the objective here, but for any material that requires rote-memory learning, such as the Associated Press or Canadian Press style rules used by news publications across North America.

  14. Minimally invasive hysterectomy in Coatis ( Nasua nasua

    Directory of Open Access Journals (Sweden)

    Bruno W. Minto

    Full Text Available ABSTRACT: Some wildlife species, such as coatis, have a high degree of adaptability to adverse conditions, such as fragmented urban forests, increasingly common on the world stage. The increase in the number of these mesopredators causes drastic changes in the communities of smaller predators, interferes with reproductive success of trees, as well as becoming a form of exchange between domestic and wild areas, favoring the transmission of zoonosis and increasing the occurrence of attacks to animals or people. This report describes the use of minimally invasive hysterectomy in two individuals of the species Nasua nasua, which can be accomplished through the use of hook technique, commonly used to castrate dogs and cats. The small incision and healing speed of incised tissues are fundamental in wild life management since the postoperative care is limited by the behavior of these animals. This technique proved to be effective and can greatly reduce the morbidity of this procedure in coatis.

  15. Non-minimal inflation revisited

    International Nuclear Information System (INIS)

    Nozari, Kourosh; Shafizadeh, Somayeh

    2010-01-01

    We reconsider an inflationary model that inflaton field is non-minimally coupled to gravity. We study the parameter space of the model up to the second (and in some cases third) order of the slow-roll parameters. We calculate inflation parameters in both Jordan and Einstein frames, and the results are compared in these two frames and also with observations. Using the recent observational data from combined WMAP5+SDSS+SNIa datasets, we study constraints imposed on our model parameters, especially the non-minimal coupling ξ.

  16. Minimal Flavor Constraints for Technicolor

    DEFF Research Database (Denmark)

    Sakuma, Hidenori; Sannino, Francesco

    2010-01-01

    We analyze the constraints on the the vacuum polarization of the standard model gauge bosons from a minimal set of flavor observables valid for a general class of models of dynamical electroweak symmetry breaking. We will show that the constraints have a strong impact on the self-coupling and mas......We analyze the constraints on the the vacuum polarization of the standard model gauge bosons from a minimal set of flavor observables valid for a general class of models of dynamical electroweak symmetry breaking. We will show that the constraints have a strong impact on the self...

  17. Harm minimization among teenage drinkers

    DEFF Research Database (Denmark)

    Jørgensen, Morten Hulvej; Curtis, Tine; Christensen, Pia Haudrup

    2007-01-01

    AIM: To examine strategies of harm minimization employed by teenage drinkers. DESIGN, SETTING AND PARTICIPANTS: Two periods of ethnographic fieldwork were conducted in a rural Danish community of approximately 2000 inhabitants. The fieldwork included 50 days of participant observation among 13....... In regulating the social context of drinking they relied on their personal experiences more than on formalized knowledge about alcohol and harm, which they had learned from prevention campaigns and educational programmes. CONCLUSIONS: In this study we found that teenagers may help each other to minimize alcohol...

  18. 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.)

  19. 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.

  20. 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

  1. [Theory and practice of minimally invasive endodontics].

    Science.gov (United States)

    Jiang, H W

    2016-08-01

    The primary goal of modern endodontic therapy is to achieve the long-term retention of a functional tooth by preventing or treating pulpitis or apical periodontitis is. The long-term retention of endodontically treated tooth is correlated with the remaining amount of tooth tissue and the quality of the restoration after root canal filling. In recent years, there has been rapid progress and development in the basic research of endodontic biology, instrument and applied materials, making treatment procedures safer, more accurate, and more efficient. Thus, minimally invasive endodontics(MIE)has received increasing attention at present. MIE aims to preserve the maximum of tooth structure during root canal therapy, and the concept covers the whole process of diagnosis and treatment of teeth. This review article focuses on describing the minimally invasive concepts and operating essentials in endodontics, from diagnosis and treatment planning to the access opening, pulp cavity finishing, root canal cleaning and shaping, 3-dimensional root canal filling and restoration after root canal treatment.

  2. Minimally invasive approach of panfacial fractures

    Directory of Open Access Journals (Sweden)

    Yudi Wijaya

    2017-08-01

    Full Text Available Background. Panfacial fractures involves fractures of several bones of face. They are associated with malocclusion, dish face deformity, enopthalmos, diplopia, cerebrospinal fluid leak and soft tissue injuries. Purpose. The purpose of this paper is to present a case of minimizing surgical wound and morbidity. Case. A 40 year old female presented with severe maxillofacial injuries caused by motor vehicle collisions about 5 days prior to admission. The assessment of the patient is mild head injury, panfacial fractures, lacerated wound at face,  rupture of globe of occular sinistra. An open reduction and internal fixation  (ORIF and enucleation of globe occular sinistra was performed.  Intraoral vestibular incision is made in the upper and lower vestibular region. Mucoperiosteal flap elevation of vestibular will exposure of the anterior maxilla and mandibular fractures. Intermaksilary fixation within 3 week and restore aesthetic with prosthesis fitting eyeball and denture. Discusion. The goal of  treatment of  panfacial fracture is to restore both the functions and pre-injury 3-dimensional facial contours. To achieve this goal two common  sequences of management of Panfacial fractures are proposed, “Bottom up and inside out” or “Top down and outside in”. Other sequences exist but there are variations of these two major approaches. Conclusion. A minimally invasive approach to  the fracture site is an alternative method  to manage panfacial fracture with a simple, effective and lower complication rate.

  3. Isoperimetric inequalities for minimal graphs

    International Nuclear Information System (INIS)

    Pacelli Bessa, G.; Montenegro, J.F.

    2007-09-01

    Based on Markvorsen and Palmer's work on mean time exit and isoperimetric inequalities we establish slightly better isoperimetric inequalities and mean time exit estimates for minimal graphs in N x R. We also prove isoperimetric inequalities for submanifolds of Hadamard spaces with tamed second fundamental form. (author)

  4. A Defense of Semantic Minimalism

    Science.gov (United States)

    Kim, Su

    2012-01-01

    Semantic Minimalism is a position about the semantic content of declarative sentences, i.e., the content that is determined entirely by syntax. It is defined by the following two points: "Point 1": The semantic content is a complete/truth-conditional proposition. "Point 2": The semantic content is useful to a theory of…

  5. Torsional Rigidity of Minimal Submanifolds

    DEFF Research Database (Denmark)

    Markvorsen, Steen; Palmer, Vicente

    2006-01-01

    We prove explicit upper bounds for the torsional rigidity of extrinsic domains of minimal submanifolds $P^m$ in ambient Riemannian manifolds $N^n$ with a pole $p$. The upper bounds are given in terms of the torsional rigidities of corresponding Schwarz symmetrizations of the domains in warped...

  6. The debate on minimal deterrence

    International Nuclear Information System (INIS)

    Arbatov, A.; Karp, R.C.; Toth, T.

    1993-01-01

    Revitalization of debates on minimal nuclear deterrence at the present time is induced by the end of the Cold War and a number of unilateral and bilateral actions by the great powers to curtail nuclear arms race and reduce nuclear weapons arsenals

  7. LLNL Waste Minimization Program Plan

    International Nuclear Information System (INIS)

    1990-01-01

    This document is the February 14, 1990 version of the LLNL Waste Minimization Program Plan (WMPP). The Waste Minimization Policy field has undergone continuous changes since its formal inception in the 1984 HSWA legislation. The first LLNL WMPP, Revision A, is dated March 1985. A series of informal revision were made on approximately a semi-annual basis. This Revision 2 is the third formal issuance of the WMPP document. EPA has issued a proposed new policy statement on source reduction and recycling. This policy reflects a preventative strategy to reduce or eliminate the generation of environmentally-harmful pollutants which may be released to the air, land surface, water, or ground water. In accordance with this new policy new guidance to hazardous waste generators on the elements of a Waste Minimization Program was issued. In response to these policies, DOE has revised and issued implementation guidance for DOE Order 5400.1, Waste Minimization Plan and Waste Reduction reporting of DOE Hazardous, Radioactive, and Radioactive Mixed Wastes, final draft January 1990. This WMPP is formatted to meet the current DOE guidance outlines. The current WMPP will be revised to reflect all of these proposed changes when guidelines are established. Updates, changes and revisions to the overall LLNL WMPP will be made as appropriate to reflect ever-changing regulatory requirements. 3 figs., 4 tabs

  8. Minimizing TLD-DRD differences

    International Nuclear Information System (INIS)

    Riley, D.L.; McCoy, R.A.; Connell, W.D.

    1987-01-01

    When substantial differences exist in exposures recorded by TLD's and DRD's, it is often necessary to perform an exposure investigation to reconcile the difference. In working with several operating plants, the authors have observed a number of causes for these differences. This paper outlines these observations and discusses procedures that can be used to minimize them

  9. Acquiring minimally invasive surgical skills

    NARCIS (Netherlands)

    Hiemstra, Ellen

    2012-01-01

    Many topics in surgical skills education have been implemented without a solid scientific basis. For that reason we have tried to find this scientific basis. We have focused on training and evaluation of minimally invasive surgical skills in a training setting and in practice in the operating room.

  10. Ultrasound elastography: advantages, limitations and artefacts of the different techniques from a study on a phantom.

    Science.gov (United States)

    Franchi-Abella, S; Elie, C; Correas, J-M

    2013-05-01

    Ultrasound elastography is a technique currently under development. Its use in clinical practice is complicated because of the wide range of techniques used by the different manufacturers and the parameters proposed to characterise tissues. A comparative analysis on five ultrasound diagnostic systems has been performed on a calibrated elasticity phantom and demonstrated that: (1) all systems tested are reliable for simple qualitative analysis: is a nodule present and is it harder or softer than neighbouring tissues? (2) the deformation or hardness ratios between two regions are usually, however, not proportional to the theoretical ratios and only a binary analysis greater than 1 (harder) and less than 1 (softer) is reliable and could be used as a negative predictive value (NPV) for malignant lesions, as has been suggested by some authors; (3) finally, quantitative analysis using shear wave techniques performed variably, reliable measurements being obtained with only one of the systems. Measurements produced by these different systems must not be compared in clinical practice to monitor a patient and the threshold values proposed in the literature must only be used in an analysis carried out with the same system and same probe. Copyright © 2013 Éditions françaises de radiologie. Published by Elsevier Masson SAS. All rights reserved.

  11. Hazardous waste minimization tracking system

    International Nuclear Information System (INIS)

    Railan, R.

    1994-01-01

    Under RCRA section 3002 9(b) and 3005f(h), hazardous waste generators and owners/operators of treatment, storage, and disposal facilities (TSDFs) are required to certify that they have a program in place to reduce the volume or quantity and toxicity of hazardous waste to the degree determined to be economically practicable. In many cases, there are environmental, as well as, economic benefits, for agencies that pursue pollution prevention options. Several state governments have already enacted waste minimization legislation (e.g., Massachusetts Toxic Use Reduction Act of 1989, and Oregon Toxic Use Reduction Act and Hazardous Waste Reduction Act, July 2, 1989). About twenty six other states have established legislation that will mandate some type of waste minimization program and/or facility planning. The need to address the HAZMIN (Hazardous Waste Minimization) Program at government agencies and private industries has prompted us to identify the importance of managing The HAZMIN Program, and tracking various aspects of the program, as well as the progress made in this area. The open-quotes WASTEclose quotes is a tracking system, which can be used and modified in maintaining the information related to Hazardous Waste Minimization Program, in a manageable fashion. This program maintains, modifies, and retrieves information related to hazardous waste minimization and recycling, and provides automated report generating capabilities. It has a built-in menu, which can be printed either in part or in full. There are instructions on preparing The Annual Waste Report, and The Annual Recycling Report. The program is very user friendly. This program is available in 3.5 inch or 5 1/4 inch floppy disks. A computer with 640K memory is required

  12. Tissue Classification

    DEFF Research Database (Denmark)

    Van Leemput, Koen; Puonti, Oula

    2015-01-01

    Computational methods for automatically segmenting magnetic resonance images of the brain have seen tremendous advances in recent years. So-called tissue classification techniques, aimed at extracting the three main brain tissue classes (white matter, gray matter, and cerebrospinal fluid), are now...... well established. In their simplest form, these methods classify voxels independently based on their intensity alone, although much more sophisticated models are typically used in practice. This article aims to give an overview of often-used computational techniques for brain tissue classification...

  13. Multiple biopsy probe sampling enabled minimally invasive electrical impedance tomography

    International Nuclear Information System (INIS)

    Shini, Mohanad; Rubinsky, Boris

    2008-01-01

    Biopsies are a reliable method for examining tissues and organs inside the body, in particular for detection of tumors. However, a single biopsy produces only limited information on the site from which it is taken. Therefore, tumor detection now employs multiple biopsy samplings to examine larger volumes of tissue. Nevertheless, even with multiple biopsies, the information remains discrete, while the costs of biopsy increase. Here we propose and evaluate the feasibility of using minimally invasive medical imaging as a means to overcome the limitations of discrete biopsy sampling. The minimally invasive medical imaging technique employs the biopsy probe as electrodes for measurements of electrical impedance tomography relevant data during each biopsy sampling. The data from multiple samplings are combined and used to produce an EIT image of the tissue. Two- and three-dimensional mathematical simulations confirm that the minimally invasive medical imaging technique can produce electrical impedance tomography images of the tissues between the biopsy probe insertion sites. We show that these images can detect tumors that would be missed with multiple biopsy samplings only, and that the technique may facilitate the detection of tumors with fewer biopsies, thereby reducing the cost of cancer detection

  14. Early outcome of minimally invasive mitral valve surgery

    Directory of Open Access Journals (Sweden)

    Shawky Fareed

    2016-08-01

    Conclusion: Right anterolateral mini-thoracotomy minimally invasive technique provides excellent exposure of the mitral valve, even with a small atrium and offers a better cosmetic lateral scar which is less prone to keloid formation. In addition, minimally invasive right anterolateral mini-thoracotomy is as safe as median sternotomy for mitral valve surgery, with fewer complications and postoperative pain, less ICU and hospital stay, fast recovery to work with no movement restriction after surgery. It should be used as an initial approach for mitral valve surgery. Furthermore, it was believed that less spreading of the incision, no interference with the diaphragm and less tissue dissection might improve outcomes, particularly respiratory function.

  15. CAT & MAUS: A novel system for true dynamic motion measurement of underlying bony structures with compensation for soft tissue movement.

    Science.gov (United States)

    Jia, Rui; Monk, Paul; Murray, David; Noble, J Alison; Mellon, Stephen

    2017-09-06

    Optoelectronic motion capture systems are widely employed to measure the movement of human joints. However, there can be a significant discrepancy between the data obtained by a motion capture system (MCS) and the actual movement of underlying bony structures, which is attributed to soft tissue artefact. In this paper, a computer-aided tracking and motion analysis with ultrasound (CAT & MAUS) system with an augmented globally optimal registration algorithm is presented to dynamically track the underlying bony structure during movement. The augmented registration part of CAT & MAUS was validated with a high system accuracy of 80%. The Euclidean distance between the marker-based bony landmark and the bony landmark tracked by CAT & MAUS was calculated to quantify the measurement error of an MCS caused by soft tissue artefact during movement. The average Euclidean distance between the target bony landmark measured by each of the CAT & MAUS system and the MCS alone varied from 8.32mm to 16.87mm in gait. This indicates the discrepancy between the MCS measured bony landmark and the actual underlying bony landmark. Moreover, Procrustes analysis was applied to demonstrate that CAT & MAUS reduces the deformation of the body segment shape modeled by markers during motion. The augmented CAT & MAUS system shows its potential to dynamically detect and locate actual underlying bony landmarks, which reduces the MCS measurement error caused by soft tissue artefact during movement. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Minimalism and the Pragmatic Frame

    Directory of Open Access Journals (Sweden)

    Ana Falcato

    2016-02-01

    Full Text Available In the debate between literalism and contextualism in semantics, Kent Bach’s project is often taken to stand on the latter side of the divide. In this paper I argue this is a misleading assumption and justify it by contrasting Bach’s assessment of the theoretical eliminability of minimal propositions arguably expressed by well-formed sentences with standard minimalist views, and by further contrasting his account of the division of interpretative processes ascribable to the semantics and pragmatics of a language with a parallel analysis carried out by the most radical opponent to semantic minimalism, i.e., by occasionalism. If my analysis proves right, the sum of its conclusions amounts to a refusal of Bach’s main dichotomies.

  17. Principle of minimal work fluctuations.

    Science.gov (United States)

    Xiao, Gaoyang; Gong, Jiangbin

    2015-08-01

    Understanding and manipulating work fluctuations in microscale and nanoscale systems are of both fundamental and practical interest. For example, in considering the Jarzynski equality 〈e-βW〉=e-βΔF, a change in the fluctuations of e-βW may impact how rapidly the statistical average of e-βW converges towards the theoretical value e-βΔF, where W is the work, β is the inverse temperature, and ΔF is the free energy difference between two equilibrium states. Motivated by our previous study aiming at the suppression of work fluctuations, here we obtain a principle of minimal work fluctuations. In brief, adiabatic processes as treated in quantum and classical adiabatic theorems yield the minimal fluctuations in e-βW. In the quantum domain, if a system initially prepared at thermal equilibrium is subjected to a work protocol but isolated from a bath during the time evolution, then a quantum adiabatic process without energy level crossing (or an assisted adiabatic process reaching the same final states as in a conventional adiabatic process) yields the minimal fluctuations in e-βW, where W is the quantum work defined by two energy measurements at the beginning and at the end of the process. In the classical domain where the classical work protocol is realizable by an adiabatic process, then the classical adiabatic process also yields the minimal fluctuations in e-βW. Numerical experiments based on a Landau-Zener process confirm our theory in the quantum domain, and our theory in the classical domain explains our previous numerical findings regarding the suppression of classical work fluctuations [G. Y. Xiao and J. B. Gong, Phys. Rev. E 90, 052132 (2014)].

  18. Optimizing Processes to Minimize Risk

    Science.gov (United States)

    Loyd, David

    2017-01-01

    NASA, like the other hazardous industries, has suffered very catastrophic losses. Human error will likely never be completely eliminated as a factor in our failures. When you can't eliminate risk, focus on mitigating the worst consequences and recovering operations. Bolstering processes to emphasize the role of integration and problem solving is key to success. Building an effective Safety Culture bolsters skill-based performance that minimizes risk and encourages successful engagement.

  19. Minimal Length, Measurability and Gravity

    Directory of Open Access Journals (Sweden)

    Alexander Shalyt-Margolin

    2016-03-01

    Full Text Available The present work is a continuation of the previous papers written by the author on the subject. In terms of the measurability (or measurable quantities notion introduced in a minimal length theory, first the consideration is given to a quantum theory in the momentum representation. The same terms are used to consider the Markov gravity model that here illustrates the general approach to studies of gravity in terms of measurable quantities.

  20. [Minimally invasive coronary artery surgery].

    Science.gov (United States)

    Zalaquett, R; Howard, M; Irarrázaval, M J; Morán, S; Maturana, G; Becker, P; Medel, J; Sacco, C; Lema, G; Canessa, R; Cruz, F

    1999-01-01

    There is a growing interest to perform a left internal mammary artery (LIMA) graft to the left anterior descending coronary artery (LAD) on a beating heart through a minimally invasive access to the chest cavity. To report the experience with minimally invasive coronary artery surgery. Analysis of 11 patients aged 48 to 79 years old with single vessel disease that, between 1996 and 1997, had a LIMA graft to the LAD performed through a minimally invasive left anterior mediastinotomy, without cardiopulmonary bypass. A 6 to 10 cm left parasternal incision was done. The LIMA to the LAD anastomosis was done after pharmacological heart rate and blood pressure control and a period of ischemic pre conditioning. Graft patency was confirmed intraoperatively by standard Doppler techniques. Patients were followed for a mean of 11.6 months (7-15 months). All patients were extubated in the operating room and transferred out of the intensive care unit on the next morning. Seven patients were discharged on the third postoperative day. Duplex scanning confirmed graft patency in all patients before discharge; in two patients, it was confirmed additionally by arteriography. There was no hospital mortality, no perioperative myocardial infarction and no bleeding problems. After follow up, ten patients were free of angina, in functional class I and pleased with the surgical and cosmetic results. One patient developed atypical angina on the seventh postoperative month and a selective arteriography confirmed stenosis of the anastomosis. A successful angioplasty of the original LAD lesion was carried out. A minimally invasive left anterior mediastinotomy is a good surgical access to perform a successful LIMA to LAD graft without cardiopulmonary bypass, allowing a shorter hospital stay and earlier postoperative recovery. However, a larger experience and a longer follow up is required to define its role in the treatment of coronary artery disease.

  1. Minimal massive 3D gravity

    International Nuclear Information System (INIS)

    Bergshoeff, Eric; Merbis, Wout; Hohm, Olaf; Routh, Alasdair J; Townsend, Paul K

    2014-01-01

    We present an alternative to topologically massive gravity (TMG) with the same ‘minimal’ bulk properties; i.e. a single local degree of freedom that is realized as a massive graviton in linearization about an anti-de Sitter (AdS) vacuum. However, in contrast to TMG, the new ‘minimal massive gravity’ has both a positive energy graviton and positive central charges for the asymptotic AdS-boundary conformal algebra. (paper)

  2. Construction schedules slack time minimizing

    Science.gov (United States)

    Krzemiński, Michał

    2017-07-01

    The article presents two copyright models for minimizing downtime working brigades. Models have been developed for construction schedules performed using the method of work uniform. Application of flow shop models is possible and useful for the implementation of large objects, which can be divided into plots. The article also presents a condition describing gives which model should be used, as well as a brief example of optimization schedule. The optimization results confirm the legitimacy of the work on the newly-developed models.

  3. Acquiring minimally invasive surgical skills

    OpenAIRE

    Hiemstra, Ellen

    2012-01-01

    Many topics in surgical skills education have been implemented without a solid scientific basis. For that reason we have tried to find this scientific basis. We have focused on training and evaluation of minimally invasive surgical skills in a training setting and in practice in the operating room. This thesis has led to an enlarged insight in the organization of surgical skills training during residency training of surgical medical specialists.

  4. A Prospective Randomized Study on Operative Treatment for Simple Distal Tibial Fractures-Minimally Invasive Plate Osteosynthesis Versus Minimal Open Reduction and Internal Fixation.

    Science.gov (United States)

    Kim, Ji Wan; Kim, Hyun Uk; Oh, Chang-Wug; Kim, Joon-Woo; Park, Ki Chul

    2018-01-01

    To compare the radiologic and clinical results of minimally invasive plate osteosynthesis (MIPO) and minimal open reduction and internal fixation (ORIF) for simple distal tibial fractures. Randomized prospective study. Three level 1 trauma centers. Fifty-eight patients with simple and distal tibial fractures were randomized into a MIPO group (treatment with MIPO; n = 29) or a minimal group (treatment with minimal ORIF; n = 29). These numbers were designed to define the rate of soft tissue complication; therefore, validation of superiority in union time or determination of differences in rates of delayed union was limited in this study. Simple distal tibial fractures treated with MIPO or minimal ORIF. The clinical outcome measurements included operative time, radiation exposure time, and soft tissue complications. To evaluate a patient's function, the American Orthopedic Foot and Ankle Society ankle score (AOFAS) was used. Radiologic measurements included fracture alignment, delayed union, and union time. All patients acquired bone union without any secondary intervention. The mean union time was 17.4 weeks and 16.3 weeks in the MIPO and minimal groups, respectively. There was 1 case of delayed union and 1 case of superficial infection in each group. The radiation exposure time was shorter in the minimal group than in the MIPO group. Coronal angulation showed a difference between both groups. The American Orthopedic Foot and Ankle Society ankle scores were 86.0 and 86.7 in the MIPO and minimal groups, respectively. Minimal ORIF resulted in similar outcomes, with no increased rate of soft tissue problems compared to MIPO. Both MIPO and minimal ORIF have high union rates and good functional outcomes for simple distal tibial fractures. Minimal ORIF did not result in increased rates of infection and wound dehiscence. Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

  5. Minimal families of curves on surfaces

    KAUST Repository

    Lubbes, Niels

    2014-01-01

    A minimal family of curves on an embedded surface is defined as a 1-dimensional family of rational curves of minimal degree, which cover the surface. We classify such minimal families using constructive methods. This allows us to compute the minimal

  6. Minimal families of curves on surfaces

    KAUST Repository

    Lubbes, Niels

    2014-11-01

    A minimal family of curves on an embedded surface is defined as a 1-dimensional family of rational curves of minimal degree, which cover the surface. We classify such minimal families using constructive methods. This allows us to compute the minimal families of a given surface.The classification of minimal families of curves can be reduced to the classification of minimal families which cover weak Del Pezzo surfaces. We classify the minimal families of weak Del Pezzo surfaces and present a table with the number of minimal families of each weak Del Pezzo surface up to Weyl equivalence.As an application of this classification we generalize some results of Schicho. We classify algebraic surfaces that carry a family of conics. We determine the minimal lexicographic degree for the parametrization of a surface that carries at least 2 minimal families. © 2014 Elsevier B.V.

  7. Studies on the strategies of minimizing radiation damage

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Hee Yong; Sohn, Young Sook

    1998-04-01

    We studied on the strategies of minimizing radiation damage in animal system. To this end we studied following areas of research (1) mechanisms involved in bone marrow damage after total body irradiation, (2) extraction of components that are useful in protecting hematopoietic system from radiation damage, (3) cell therapy approach in restoring the damaged tissue, (4) development of radioprotective chemical reagent, and (5) epidemiological study on the population that had been exposed to radiation.

  8. Studies on the strategies of minimizing radiation damage

    International Nuclear Information System (INIS)

    Chung, Hee Yong; Sohn, Young Sook

    1998-04-01

    We studied on the strategies of minimizing radiation damage in animal system. To this end we studied following areas of research 1) mechanisms involved in bone marrow damage after total body irradiation, 2) extraction of components that are useful in protecting hematopoietic system from radiation damage, 3) cell therapy approach in restoring the damaged tissue, 4) development of radioprotective chemical reagent, and 5) epidemiological study on the population that had been exposed to radiation

  9. 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.

  10. An investigation of head movement with a view to minimising motion artefact during SPECT and PET imaging of the brain

    International Nuclear Information System (INIS)

    Patterson, H.; Clarke, G.H.; Guy, R.; McKay, W.J.

    1998-01-01

    Full text: Motion artefact has long been recognised as a major cause of image degradation. Single Photon Emission Computerised Tomography (SPECT) and Positron Emission Tomography (PET) of the brain are playing an important role in the diagnosis and management of several neurological disorders. If these imaging modalities are to contribute fully to medical imaging it is essential that the improved spatial resolution of these systems is not compromised by patient movement. Thirty volunteer subjects have been examined using a simple video technique and the video images were used to classify and measure head movements which may occur during brain imaging. All subjects demonstrated angular movement within the transverse plane or rotation of the head. Angular movement within the sagittal plane or flexion/extension of the neck occurred in 69% of subjects and 72% of subjects exhibited translational movement of the sagittal plane. There was no movement of the coronal plane; nor was there any translational movement of the sagittal plane. These results suggest that when positioning the patient's head for brain imaging a system of head restraint which minimises rotation of the head should be used if image quality is to be maintained

  11. The Structure of Artefacts of Management Control in the Innovation Process: Does Exist Association with the Strategic Profile?

    Directory of Open Access Journals (Sweden)

    Fábio Frezatti

    2015-01-01

    Full Text Available This study investigates what is the role of strateg ic profiles and management control instruments in organisations’ innovation process. B ased in a survey using structural equation modelling (121 companies, we confirm that analyser , defender e prospector profiles are associated with strategic planning, balanced scorec ard (BSC and rolling forecast. The reactor type is associated with lower use of artefacts. Our results confirm the linkage between incremental innovation and strategic planning and b etween radical innovation and BSC. These findings reflect the alignment between strate gic types, the availability of instruments and intensity of innovation, which is useful inform ation with which to understand organisations and their market activities. This pap er bring information about specific management control instruments existence and the im pact for the intensity of the innovation that is relevant for management and must stimulate organizations to be consistent in the cases that the strategic profile is a clear long term def inition or see the possibility of change when it is not the desired one.

  12. A Multi-Channel Opto-Electronic Sensor to Accurately Monitor Heart Rate against Motion Artefact during Exercise

    Directory of Open Access Journals (Sweden)

    Abdullah Alzahrani

    2015-10-01

    Full Text Available This study presents the use of a multi-channel opto-electronic sensor (OEPS to effectively monitor critical physiological parameters whilst preventing motion artefact as increasingly demanded by personal healthcare. The aim of this work was to study how to capture the heart rate (HR efficiently through a well-constructed OEPS and a 3-axis accelerometer with wireless communication. A protocol was designed to incorporate sitting, standing, walking, running and cycling. The datasets collected from these activities were processed to elaborate sport physiological effects. t-test, Bland-Altman Agreement (BAA, and correlation to evaluate the performance of the OEPS were used against Polar and Mio-Alpha HR monitors. No differences in the HR were found between OEPS, and either Polar or Mio-Alpha (both p > 0.05; a strong correlation was found between Polar and OEPS (r: 0.96, p < 0.001; the bias of BAA 0.85 bpm, the standard deviation (SD 9.20 bpm, and the limits of agreement (LOA from −17.18 bpm to +18.88 bpm. For the Mio-Alpha and OEPS, a strong correlation was found (r: 0.96, p < 0.001; the bias of BAA 1.63 bpm, SD 8.62 bpm, LOA from −15.27 bpm to +18.58 bpm. These results demonstrate the OEPS to be capable of carrying out real time and remote monitoring of heart rate.

  13. 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.

  14. 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

  15. 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

  16. Identification of the earliest collagen- and plant-based coatings from Neolithic artefacts (Nahal Hemar cave, Israel).

    Science.gov (United States)

    Solazzo, Caroline; Courel, Blandine; Connan, Jacques; van Dongen, Bart E; Barden, Holly; Penkman, Kirsty; Taylor, Sheila; Demarchi, Beatrice; Adam, Pierre; Schaeffer, Philippe; Nissenbaum, Arie; Bar-Yosef, Ofer; Buckley, Michael

    2016-08-09

    Mortuary practices in human evolution record cognitive, social changes and technological innovations. The Neolithic Revolution in the Levant was a watershed in this domain that has long fascinated the archaeological community. Plaster modelled skulls are well known at Jericho and several other Neolithic sites, and in Nahal Hemar cave (Israel, ca. 8200 -7300 cal. BC) excavations yielded six unique human skulls covered with a black organic coating applied in a net pattern evoking a headdress. This small cave was used as storage for paraphernalia in the semi-arid area of the Judean desert and the dry conditions preserved other artefacts such as baskets coated with a similar dark substance. While previous analysis had revealed the presence of amino acids consistent with a collagen signature, in the present report, specific biomarkers were characterised using combined proteomic and lipid approaches. Basket samples yielded collagen and blood proteins of bovine origin (Bos genus) and a large sequence coverage of a plant protein charybdin (Charybdis genus). The skull residue samples were dominated by benzoate and cinnamate derivatives and triterpenes consistent with a styrax-type resin (Styrax officinalis), thus providing the earliest known evidence of an odoriferous plant resin used in combination with an animal product.

  17. Study of SEM preparation artefacts with correlative microscopy: Cell shrinkage of adherent cells by HMDS-drying.

    Science.gov (United States)

    Katsen-Globa, Alisa; Puetz, Norbert; Gepp, Michael M; Neubauer, Julia C; Zimmermann, Heiko

    2016-11-01

    One of the often reported artefacts during cell preparation to scanning electron microscopy (SEM) is the shrinkage of cellular objects, that mostly occurs at a certain time-dependent stage of cell drying. Various methods of drying for SEM, such as critical point drying, freeze-drying, as well as hexamethyldisilazane (HMDS)-drying, were usually used. The latter becomes popular since it is a low cost and fast method. However, the correlation of drying duration and real shrinkage of objects was not investigated yet. In this paper, cell shrinkage at each stage of preparation for SEM was studied. We introduce a shrinkage coefficient using correlative light microscopy (LM) and SEM of the same human mesenchymal stem cells (hMSCs). The influence of HMDS-drying duration on the cell shrinkage is shown: the longer drying duration, the more shrinkage is observed. Furthermore, it was demonstrated that cell shrinkage is inversely proportional to cultivation time: the longer cultivation time, the more cell spreading area and the less cell shrinkage. Our results can be applicable for an exact SEM quantification of cell size and determination of cell spreading area in engineering of artificial cellular environments using biomaterials. SCANNING 38:625-633, 2016. © 2016 Wiley Periodicals, Inc. © Wiley Periodicals, Inc.

  18. Atraumatic restorative treatment and minimal intervention dentistry.

    Science.gov (United States)

    Frencken, J E

    2017-08-11

    Too many people worldwide suffer from the consequences of untreated dentine carious lesions. This finding reflects the inability of the currently used traditional mode of treatments to manage such lesions. A change is needed. Dental training institutions should depart from the traditional 'drill and fill' treatments and embrace the holistic oral healthcare approach that is minimal intervention dentistry (MID) and includes within it minimally invasive operative skills. Dental caries is, after all, a preventable disease. The atraumatic restorative treatment (ART) concept is an example of MID. ART consists of a preventive (ART sealant) and a restorative (ART restoration) component. ART sealants using high-viscosity glass-ionomer (HVGIC) have a very high dentine carious lesion preventive effect. The survival rate of these sealants is not significantly different from that of sealants produced with resin. The survival rate of ART/HVGIC restorations matches those of amalgam and resin composite in single- and multiple-surface cavities in primary teeth and in single-surface cavities in permanent teeth. The principles of carious tissue removal within a cavity recommended by the International Caries Consensus Collaboration are in line with those of treating a cavity using ART. Owing to its good performance and the low levels of discomfort/pain and dental anxiety associated with it, ART and/or other evidence-based atraumatic care procedures should be the first treatment for a primary dentine carious lesion. Only if the use of ART is not indicated should other more invasive and less-atraumatic care procedures be used in both primary and permanent dentitions.

  19. 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.

  20. 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...

  1. Complications of minimally invasive cosmetic procedures: Prevention and management

    Directory of Open Access Journals (Sweden)

    Lauren L Levy

    2012-01-01

    Full Text Available Over the past decade, facial rejuvenation procedures to circumvent traditional surgery have become increasingly popular. Office-based, minimally invasive procedures can promote a youthful appearance with minimal downtime and low risk of complications. Injectable botulinum toxin (BoNT, soft-tissue fillers, and chemical peels are among the most popular non-invasive rejuvenation procedures, and each has unique applications for improving facial aesthetics. Despite the simplicity and reliability of office-based procedures, complications can occur even with an astute and experienced injector. The goal of any procedure is to perform it properly and safely; thus, early recognition of complications when they do occur is paramount in dictating prevention of long-term sequelae. The most common complications from BoNT and soft-tissue filler injection are bruising, erythema and pain. With chemical peels, it is not uncommon to have erythema, irritation and burning. Fortunately, these side effects are normally transient and have simple remedies. More serious complications include muscle paralysis from BoNT, granuloma formation from soft-tissue filler placement and scarring from chemical peels. Thankfully, these complications are rare and can be avoided with excellent procedure technique, knowledge of facial anatomy, proper patient selection, and appropriate pre- and post-skin care. This article reviews complications of office-based, minimally invasive procedures, with emphasis on prevention and management. Practitioners providing these treatments should be well versed in this subject matter in order to deliver the highest quality care.

  2. LLNL Waste Minimization Program Plan

    International Nuclear Information System (INIS)

    1990-05-01

    This document is the February 14, 1990 version of the LLNL Waste Minimization Program Plan (WMPP). Now legislation at the federal level is being introduced. Passage will result in new EPA regulations and also DOE orders. At the state level the Hazardous Waste Reduction and Management Review Act of 1989 was signed by the Governor. DHS is currently promulgating regulations to implement the new law. EPA has issued a proposed new policy statement on source reduction and recycling. This policy reflects a preventative strategy to reduce or eliminate the generation of environmentally-harmful pollutants which may be released to the air, land surface, water, or ground water. In accordance with this policy new guidance to hazardous waste generators on the elements of a Waste Minimization Program was issued. This WMPP is formatted to meet the current DOE guidance outlines. The current WMPP will be revised to reflect all of these proposed changes when guidelines are established. Updates, changes and revisions to the overall LLNL WMPP will be made as appropriate to reflect ever-changing regulatory requirements

  3. Symmetry breaking for drag minimization

    Science.gov (United States)

    Roper, Marcus; Squires, Todd M.; Brenner, Michael P.

    2005-11-01

    For locomotion at high Reynolds numbers drag minimization favors fore-aft asymmetric slender shapes with blunt noses and sharp trailing edges. On the other hand, in an inertialess fluid the drag experienced by a body is independent of whether it travels forward or backward through the fluid, so there is no advantage to having a single preferred swimming direction. In fact numerically determined minimum drag shapes are known to exhibit almost no fore-aft asymmetry even at moderate Re. We show that asymmetry persists, albeit extremely weakly, down to vanishingly small Re, scaling asymptotically as Re^3. The need to minimize drag to maximize speed for a given propulsive capacity gives one possible mechanism for the increasing asymmetry in the body plans seen in nature, as organisms increase in size and swimming speed from bacteria like E-Coli up to pursuit predator fish such as tuna. If it is the dominant mechanism, then this signature scaling will be observed in the shapes of motile micro-organisms.

  4. 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.

  5. Fibrovascular tissue in bilateral juxtafoveal telangiectasis.

    Science.gov (United States)

    Park, D; Schatz, H; McDonald, H R; Johnson, R N

    1996-09-01

    To study the natural history and retinal findings associated with the intraretinal and subretinal fibrovascular tissues that develop in the late phases of bilateral juxtafoveal telangiectasis. The records of 10 patients (11 eyes) with bilateral juxtafoveal telangiectasis who developed these fibrovascular tissues were examined. Throughout the follow-up period (average 44 months), only 2 eyes (18%) lost 2 or more lines of vision; the final visual acuities were similar for the eyes both with and without fibrovascular tissues. Sixty-four percent of fibrovascular tissues showed little to no growth. Eyes with fibrovascular tissue commonly had retinal pigment epithelial hyperplasia (72%), draining retinal venules (82%), and retinal vascular distortion (64%). Fibrovascular tissues of bilateral juxtafoveal telangiectasis have little proliferative potential and minimal effects on visual acuity. Nevertheless, these fibrovascular tissues do remodel over time, leading to retinal vascular distortion. Given these benign findings, the role of laser photocoagulation treatment of these tissues is questionable.

  6. Laparoscopic colonic resection in inflammatory bowel disease: minimal surgery, minimal access and minimal hospital stay.

    LENUS (Irish Health Repository)

    Boyle, E

    2008-11-01

    Laparoscopic surgery for inflammatory bowel disease (IBD) is technically demanding but can offer improved short-term outcomes. The introduction of minimally invasive surgery (MIS) as the default operative approach for IBD, however, may have inherent learning curve-associated disadvantages. We hypothesise that the establishment of MIS as the standard operative approach does not increase patient morbidity as assessed in the initial period of its introduction into a specialised unit, and that it confers earlier postoperative gastrointestinal recovery and reduced hospitalisation compared with conventional open resection.

  7. Minimally invasive aortic valve replacement

    DEFF Research Database (Denmark)

    Foghsgaard, Signe; Schmidt, Thomas Andersen; Kjaergard, Henrik K

    2009-01-01

    In this descriptive prospective study, we evaluate the outcomes of surgery in 98 patients who were scheduled to undergo minimally invasive aortic valve replacement. These patients were compared with a group of 50 patients who underwent scheduled aortic valve replacement through a full sternotomy...... operations were completed as mini-sternotomies, 4 died later of noncardiac causes. The aortic cross-clamp and perfusion times were significantly different across all groups (P replacement...... is an excellent operation in selected patients, but its true advantages over conventional aortic valve replacement (other than a smaller scar) await evaluation by means of randomized clinical trial. The "extended mini-aortic valve replacement" operation, on the other hand, is a risky procedure that should...

  8. Minimization over randomly selected lines

    Directory of Open Access Journals (Sweden)

    Ismet Sahin

    2013-07-01

    Full Text Available This paper presents a population-based evolutionary optimization method for minimizing a given cost function. The mutation operator of this method selects randomly oriented lines in the cost function domain, constructs quadratic functions interpolating the cost function at three different points over each line, and uses extrema of the quadratics as mutated points. The crossover operator modifies each mutated point based on components of two points in population, instead of one point as is usually performed in other evolutionary algorithms. The stopping criterion of this method depends on the number of almost degenerate quadratics. We demonstrate that the proposed method with these mutation and crossover operations achieves faster and more robust convergence than the well-known Differential Evolution and Particle Swarm algorithms.

  9. Strategies to Minimize Antibiotic Resistance

    Directory of Open Access Journals (Sweden)

    Sang Hee Lee

    2013-09-01

    Full Text Available Antibiotic resistance can be reduced by using antibiotics prudently based on guidelines of antimicrobial stewardship programs (ASPs and various data such as pharmacokinetic (PK and pharmacodynamic (PD properties of antibiotics, diagnostic testing, antimicrobial susceptibility testing (AST, clinical response, and effects on the microbiota, as well as by new antibiotic developments. The controlled use of antibiotics in food animals is another cornerstone among efforts to reduce antibiotic resistance. All major resistance-control strategies recommend education for patients, children (e.g., through schools and day care, the public, and relevant healthcare professionals (e.g., primary-care physicians, pharmacists, and medical students regarding unique features of bacterial infections and antibiotics, prudent antibiotic prescribing as a positive construct, and personal hygiene (e.g., handwashing. The problem of antibiotic resistance can be minimized only by concerted efforts of all members of society for ensuring the continued efficiency of antibiotics.

  10. A minimally invasive smile enhancement.

    Science.gov (United States)

    Peck, Fred H

    2014-01-01

    Minimally invasive dentistry refers to a wide variety of dental treatments. On the restorative aspect of dental procedures, direct resin bonding can be a very conservative treatment option for the patient. When tooth structure does not need to be removed, the patient benefits. Proper treatment planning is essential to determine how conservative the restorative treatment will be. This article describes the diagnosis, treatment options, and procedural techniques in the restoration of 4 maxillary anterior teeth with direct composite resin. The procedural steps are reviewed with regard to placing the composite and the variety of colors needed to ensure a natural result. Finishing and polishing of the composite are critical to ending with a natural looking dentition that the patient will be pleased with for many years.

  11. Waste minimization in analytical methods

    International Nuclear Information System (INIS)

    Green, D.W.; Smith, L.L.; Crain, J.S.; Boparai, A.S.; Kiely, J.T.; Yaeger, J.S. Schilling, J.B.

    1995-01-01

    The US Department of Energy (DOE) will require a large number of waste characterizations over a multi-year period to accomplish the Department's goals in environmental restoration and waste management. Estimates vary, but two million analyses annually are expected. The waste generated by the analytical procedures used for characterizations is a significant source of new DOE waste. Success in reducing the volume of secondary waste and the costs of handling this waste would significantly decrease the overall cost of this DOE program. Selection of appropriate analytical methods depends on the intended use of the resultant data. It is not always necessary to use a high-powered analytical method, typically at higher cost, to obtain data needed to make decisions about waste management. Indeed, for samples taken from some heterogeneous systems, the meaning of high accuracy becomes clouded if the data generated are intended to measure a property of this system. Among the factors to be considered in selecting the analytical method are the lower limit of detection, accuracy, turnaround time, cost, reproducibility (precision), interferences, and simplicity. Occasionally, there must be tradeoffs among these factors to achieve the multiple goals of a characterization program. The purpose of the work described here is to add waste minimization to the list of characteristics to be considered. In this paper the authors present results of modifying analytical methods for waste characterization to reduce both the cost of analysis and volume of secondary wastes. Although tradeoffs may be required to minimize waste while still generating data of acceptable quality for the decision-making process, they have data demonstrating that wastes can be reduced in some cases without sacrificing accuracy or precision

  12. 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.)

  13. PIXE and PGAA - Complementary methods for studies on ancient glass artefacts (from Byzantine, late medieval to modern Murano glass)

    Science.gov (United States)

    Constantinescu, Bogdan; Cristea-Stan, Daniela; Szőkefalvi-Nagy, Zoltán; Kovács, Imre; Harsányi, Ildikó; Kasztovszky, Zsolt

    2018-02-01

    Combined external milli-beam Particle Induced X-ray Emission (PIXE) and Prompt Gamma Activation Analysis (PGAA) analysis was applied to characterize the composition of paste and colorants from some fragments of Byzantine bracelets (10th-12th Centuries AD), late medieval (17th-18th Centuries AD) and modern Murano glass pieces. As fluxes, PGAA revealed the samples are soda-lime glass, except four samples - two medieval vessel white shards and two dark Byzantine fragments of bracelets - which have potash flux. Aluminium was detected in various proportions in all samples indicating different sources for the added sand. The presence of Magnesium is relevant only in one bracelet fragment suggesting the use of plant (wood?) ash and confirming that the Byzantine bracelet is manufactured from the mixture of both types of glass (natron and plant ash based). PGAA also indicated the presence of low quantities of Cadmium, high level of Arsenic and Lead (possibly lead arsenate) in one medieval sample and of ZnO in Murano glass, and of CoO traces (maximum 0.1%) in all blue-colored Byzantine, late medieval to modern Murano glass artefacts. PIXE confirmed the use of small quantities of CoO for blue color, indicated Manganese combined with Iron for dark glass, Copper for green, Lead, Tin and an Arsenic compound (orpiment?) for yellow and in the case of modern Murano glass Selenium and Cadmium to obtain a reddish color. Despite PIXE - PIGE combination is probably the best one for glass analysis, our external milli-PIXE - PGAA methods proved to be adequate complementary tools to determine many chemical elements from glass composition - Si, Na, K, Ca, Al, Mg, various metallic oxides.

  14. Cyclone Simulation via Action Minimization

    Science.gov (United States)

    Plotkin, D. A.; Weare, J.; Abbot, D. S.

    2016-12-01

    A postulated impact of climate change is an increase in intensity of tropical cyclones (TCs). This hypothesized effect results from the fact that TCs are powered subsaturated boundary layer air picking up water vapor from the surface ocean as it flows inwards towards the eye. This water vapor serves as the energy input for TCs, which can be idealized as heat engines. The inflowing air has a nearly identical temperature as the surface ocean; therefore, warming of the surface leads to a warmer atmospheric boundary layer. By the Clausius-Clapeyron relationship, warmer boundary layer air can hold more water vapor and thus results in more energetic storms. Changes in TC intensity are difficult to predict due to the presence of fine structures (e.g. convective structures and rainbands) with length scales of less than 1 km, while general circulation models (GCMs) generally have horizontal resolutions of tens of kilometers. The models are therefore unable to capture these features, which are critical to accurately simulating cyclone structure and intensity. Further, strong TCs are rare events, meaning that long multi-decadal simulations are necessary to generate meaningful statistics about intense TC activity. This adds to the computational expense, making it yet more difficult to generate accurate statistics about long-term changes in TC intensity due to global warming via direct simulation. We take an alternative approach, applying action minimization techniques developed in molecular dynamics to the WRF weather/climate model. We construct artificial model trajectories that lead from quiescent (TC-free) states to TC states, then minimize the deviation of these trajectories from true model dynamics. We can thus create Monte Carlo model ensembles that are biased towards cyclogenesis, which reduces computational expense by limiting time spent in non-TC states. This allows for: 1) selective interrogation of model states with TCs; 2) finding the likeliest paths for

  15. Thermal damage control of dye-assisted laser tissue welding: effect of dye concentration

    Science.gov (United States)

    Xie, Hua; Buckley, Lisa A.; Prahl, Scott A.; Shaffer, Brian S.; Gregory, Kenton W.

    2001-05-01

    Successful laser-assisted tissue welding was implemented to provide proper weld strength with minimized tissue thermal injury. We investigated and compared the weld strengths and morphologic changes in porcine small intestinal submucose (SIS) and porcine ureteral tissues with various concentration of indocyanine green (ICG) and with a solid albumin sheet. The study showed that the tissues were welded at lower ICG concentration (0.05 mM) with minimized tissue thermal damage using an 800-nm wavelength diode laser.

  16. Commercial considerations in tissue engineering.

    Science.gov (United States)

    Mansbridge, Jonathan

    2006-10-01

    Tissue engineering is a field with immense promise. Using the example of an early tissue-engineered skin implant, Dermagraft, factors involved in the successful commercial development of devices of this type are explored. Tissue engineering has to strike a balance between tissue culture, which is a resource-intensive activity, and business considerations that are concerned with minimizing cost and maximizing customer convenience. Bioreactor design takes place in a highly regulated environment, so factors to be incorporated into the concept include not only tissue culture considerations but also matters related to asepsis, scaleup, automation and ease of use by the final customer. Dermagraft is an allogeneic tissue. Stasis preservation, in this case cryopreservation, is essential in allogeneic tissue engineering, allowing sterility testing, inventory control and, in the case of Dermagraft, a cellular stress that may be important for hormesis following implantation. Although the use of allogeneic cells provides advantages in manufacturing under suitable conditions, it raises the spectre of immunological rejection. Such rejection has not been experienced with Dermagraft. Possible reasons for this and the vision of further application of allogeneic tissues are important considerations in future tissue-engineered cellular devices. This review illustrates approaches that indicate some of the criteria that may provide a basis for further developments. Marketing is a further requirement for success, which entails understanding of the mechanism of action of the procedure, and is illustrated for Dermagraft. The success of a tissue-engineered product is dependent on many interacting operations, some discussed here, each of which must be performed simultaneously and well.

  17. Minimalism through intraoperative functional mapping.

    Science.gov (United States)

    Berger, M S

    1996-01-01

    Intraoperative stimulation mapping may be used to avoid unnecessary risk to functional regions subserving language and sensori-motor pathways. Based on the data presented here, language localization is variable in the entire population, with only certainty existing for the inferior frontal region responsible for motor speech. Anatomical landmarks such as the anterior temporal tip for temporal lobe language sites and the posterior aspect of the lateral sphenoid wing for the frontal lobe language zones are unreliable in avoiding postoperative aphasias. Thus, individual mapping to identify essential language sites has the greatest likelihood of avoiding permanent deficits in naming, reading, and motor speech. In a similar approach, motor and sensory pathways from the cortex and underlying white matter may be reliably stimulated and mapped in both awake and asleep patients. Although these techniques require an additional operative time and equipment nominally priced, the result is often gratifying, as postoperative morbidity has been greatly reduced in the process of incorporating these surgical strategies. The patients quality of life is improved in terms of seizure control, with or without antiepileptic drugs. This avoids having to perform a second costly operative procedure, which is routinely done when extraoperative stimulation and recording is done via subdural grids. In addition, an aggressive tumor resection at the initial operation lengthens the time to tumor recurrence and often obviates the need for a subsequent reoperation. Thus, intraoperative functional mapping may be best alluded to as a surgical technique that results in "minimalism in the long term".

  18. Against explanatory minimalism in psychiatry

    Directory of Open Access Journals (Sweden)

    Tim eThornton

    2015-12-01

    Full Text Available The idea that psychiatry contains, in principle, a series of levels of explanation has been criticised both as empirically false but also, by Campbell, as unintelligible because it presupposes a discredited pre-Humean view of causation. Campbell’s criticism is based on an interventionist-inspired denial that mechanisms and rational connections underpin physical and mental causation respectively and hence underpin levels of explanation. These claims echo some superficially similar remarks in Wittgenstein’s Zettel. But attention to the context of Wittgenstein’s remarks suggests a reason to reject explanatory minimalism in psychiatry and reinstate a Wittgensteinian notion of level of explanation. Only in a context broader than the one provided by interventionism is the ascription of propositional attitudes, even in the puzzling case of delusions, justified. Such a view, informed by Wittgenstein, can reconcile the idea that the ascription mental phenomena presupposes a particular level of explanation with the rejection of an a priori claim about its connection to a neurological level of explanation.

  19. Against Explanatory Minimalism in Psychiatry.

    Science.gov (United States)

    Thornton, Tim

    2015-01-01

    The idea that psychiatry contains, in principle, a series of levels of explanation has been criticized not only as empirically false but also, by Campbell, as unintelligible because it presupposes a discredited pre-Humean view of causation. Campbell's criticism is based on an interventionist-inspired denial that mechanisms and rational connections underpin physical and mental causation, respectively, and hence underpin levels of explanation. These claims echo some superficially similar remarks in Wittgenstein's Zettel. But attention to the context of Wittgenstein's remarks suggests a reason to reject explanatory minimalism in psychiatry and reinstate a Wittgensteinian notion of levels of explanation. Only in a context broader than the one provided by interventionism is that the ascription of propositional attitudes, even in the puzzling case of delusions, justified. Such a view, informed by Wittgenstein, can reconcile the idea that the ascription mental phenomena presupposes a particular level of explanation with the rejection of an a priori claim about its connection to a neurological level of explanation.

  20. Robotic assisted minimally invasive surgery

    Directory of Open Access Journals (Sweden)

    Palep Jaydeep

    2009-01-01

    Full Text Available The term "robot" was coined by the Czech playright Karel Capek in 1921 in his play Rossom′s Universal Robots. The word "robot" is from the check word robota which means forced labor.The era of robots in surgery commenced in 1994 when the first AESOP (voice controlled camera holder prototype robot was used clinically in 1993 and then marketed as the first surgical robot ever in 1994 by the US FDA. Since then many robot prototypes like the Endoassist (Armstrong Healthcare Ltd., High Wycombe, Buck, UK, FIPS endoarm (Karlsruhe Research Center, Karlsruhe, Germany have been developed to add to the functions of the robot and try and increase its utility. Integrated Surgical Systems (now Intuitive Surgery, Inc. redesigned the SRI Green Telepresence Surgery system and created the daVinci Surgical System ® classified as a master-slave surgical system. It uses true 3-D visualization and EndoWrist ® . It was approved by FDA in July 2000 for general laparoscopic surgery, in November 2002 for mitral valve repair surgery. The da Vinci robot is currently being used in various fields such as urology, general surgery, gynecology, cardio-thoracic, pediatric and ENT surgery. It provides several advantages to conventional laparoscopy such as 3D vision, motion scaling, intuitive movements, visual immersion and tremor filtration. The advent of robotics has increased the use of minimally invasive surgery among laparoscopically naοve surgeons and expanded the repertoire of experienced surgeons to include more advanced and complex reconstructions.

  1. Tissue irradiator

    International Nuclear Information System (INIS)

    Hungate, F.P.; Riemath, W.F.; Bunnell, L.R.

    1975-01-01

    A tissue irradiator is provided for the in-vivo irradiation of body tissue. The irradiator comprises a radiation source material contained and completely encapsulated within vitreous carbon. An embodiment for use as an in-vivo blood irradiator comprises a cylindrical body having an axial bore therethrough. A radioisotope is contained within a first portion of vitreous carbon cylindrically surrounding the axial bore, and a containment portion of vitreous carbon surrounds the radioisotope containing portion, the two portions of vitreous carbon being integrally formed as a single unit. Connecting means are provided at each end of the cylindrical body to permit connections to blood-carrying vessels and to provide for passage of blood through the bore. In a preferred embodiment, the radioisotope is thulium-170 which is present in the irradiator in the form of thulium oxide. A method of producing the preferred blood irradiator is also provided, whereby nonradioactive thulium-169 is dispersed within a polyfurfuryl alcohol resin which is carbonized and fired to form the integral vitreous carbon body and the device is activated by neutron bombardment of the thulium-169 to produce the beta-emitting thulium-170

  2. Tissue-electronics interfaces: from implantable devices to engineered tissues

    Science.gov (United States)

    Feiner, Ron; Dvir, Tal

    2018-01-01

    Biomedical electronic devices are interfaced with the human body to extract precise medical data and to interfere with tissue function by providing electrical stimuli. In this Review, we outline physiologically and pathologically relevant tissue properties and processes that are important for designing implantable electronic devices. We summarize design principles for flexible and stretchable electronics that adapt to the mechanics of soft tissues, such as those including conducting polymers, liquid metal alloys, metallic buckling and meandering architectures. We further discuss technologies for inserting devices into the body in a minimally invasive manner and for eliminating them without further intervention. Finally, we introduce the concept of integrating electronic devices with biomaterials and cells, and we envision how such technologies may lead to the development of bionic organs for regenerative medicine.

  3. Prevailing Trends in Haptic Feedback Simulation for Minimally Invasive Surgery.

    Science.gov (United States)

    Pinzon, David; Byrns, Simon; Zheng, Bin

    2016-08-01

    Background The amount of direct hand-tool-tissue interaction and feedback in minimally invasive surgery varies from being attenuated in laparoscopy to being completely absent in robotic minimally invasive surgery. The role of haptic feedback during surgical skill acquisition and its emphasis in training have been a constant source of controversy. This review discusses the major developments in haptic simulation as they relate to surgical performance and the current research questions that remain unanswered. Search Strategy An in-depth review of the literature was performed using PubMed. Results A total of 198 abstracts were returned based on our search criteria. Three major areas of research were identified, including advancements in 1 of the 4 components of haptic systems, evaluating the effectiveness of haptic integration in simulators, and improvements to haptic feedback in robotic surgery. Conclusions Force feedback is the best method for tissue identification in minimally invasive surgery and haptic feedback provides the greatest benefit to surgical novices in the early stages of their training. New technology has improved our ability to capture, playback and enhance to utility of haptic cues in simulated surgery. Future research should focus on deciphering how haptic training in surgical education can increase performance, safety, and improve training efficiency. © The Author(s) 2016.

  4. Is non-minimal inflation eternal?

    International Nuclear Information System (INIS)

    Feng, Chao-Jun; Li, Xin-Zhou

    2010-01-01

    The possibility that the non-minimal coupling inflation could be eternal is investigated. We calculate the quantum fluctuation of the inflaton in a Hubble time and find that it has the same value as that in the minimal case in the slow-roll limit. Armed with this result, we have studied some concrete non-minimal inflationary models including the chaotic inflation and the natural inflation, in which the inflaton is non-minimally coupled to the gravity. We find that the non-minimal coupling inflation could be eternal in some parameter spaces.

  5. Minimal nuclear energy density functional

    Science.gov (United States)

    Bulgac, Aurel; Forbes, Michael McNeil; Jin, Shi; Perez, Rodrigo Navarro; Schunck, Nicolas

    2018-04-01

    We present a minimal nuclear energy density functional (NEDF) called "SeaLL1" that has the smallest number of possible phenomenological parameters to date. SeaLL1 is defined by seven significant phenomenological parameters, each related to a specific nuclear property. It describes the nuclear masses of even-even nuclei with a mean energy error of 0.97 MeV and a standard deviation of 1.46 MeV , two-neutron and two-proton separation energies with rms errors of 0.69 MeV and 0.59 MeV respectively, and the charge radii of 345 even-even nuclei with a mean error ɛr=0.022 fm and a standard deviation σr=0.025 fm . SeaLL1 incorporates constraints on the equation of state (EoS) of pure neutron matter from quantum Monte Carlo calculations with chiral effective field theory two-body (NN ) interactions at the next-to-next-to-next-to leading order (N3LO) level and three-body (NNN ) interactions at the next-to-next-to leading order (N2LO) level. Two of the seven parameters are related to the saturation density and the energy per particle of the homogeneous symmetric nuclear matter, one is related to the nuclear surface tension, two are related to the symmetry energy and its density dependence, one is related to the strength of the spin-orbit interaction, and one is the coupling constant of the pairing interaction. We identify additional phenomenological parameters that have little effect on ground-state properties but can be used to fine-tune features such as the Thomas-Reiche-Kuhn sum rule, the excitation energy of the giant dipole and Gamow-Teller resonances, the static dipole electric polarizability, and the neutron skin thickness.

  6. Minimal models of multidimensional computations.

    Directory of Open Access Journals (Sweden)

    Jeffrey D Fitzgerald

    2011-03-01

    Full Text Available The multidimensional computations performed by many biological systems are often characterized with limited information about the correlations between inputs and outputs. Given this limitation, our approach is to construct the maximum noise entropy response function of the system, leading to a closed-form and minimally biased model consistent with a given set of constraints on the input/output moments; the result is equivalent to conditional random field models from machine learning. For systems with binary outputs, such as neurons encoding sensory stimuli, the maximum noise entropy models are logistic functions whose arguments depend on the constraints. A constraint on the average output turns the binary maximum noise entropy models into minimum mutual information models, allowing for the calculation of the information content of the constraints and an information theoretic characterization of the system's computations. We use this approach to analyze the nonlinear input/output functions in macaque retina and thalamus; although these systems have been previously shown to be responsive to two input dimensions, the functional form of the response function in this reduced space had not been unambiguously identified. A second order model based on the logistic function is found to be both necessary and sufficient to accurately describe the neural responses to naturalistic stimuli, accounting for an average of 93% of the mutual information with a small number of parameters. Thus, despite the fact that the stimulus is highly non-Gaussian, the vast majority of the information in the neural responses is related to first and second order correlations. Our results suggest a principled and unbiased way to model multidimensional computations and determine the statistics of the inputs that are being encoded in the outputs.

  7. Westinghouse Hanford Company waste minimization actions

    International Nuclear Information System (INIS)

    Greenhalgh, W.O.

    1988-09-01

    Companies that generate hazardous waste materials are now required by national regulations to establish a waste minimization program. Accordingly, in FY88 the Westinghouse Hanford Company formed a waste minimization team organization. The purpose of the team is to assist the company in its efforts to minimize the generation of waste, train personnel on waste minimization techniques, document successful waste minimization effects, track dollar savings realized, and to publicize and administer an employee incentive program. A number of significant actions have been successful, resulting in the savings of materials and dollars. The team itself has been successful in establishing some worthwhile minimization projects. This document briefly describes the waste minimization actions that have been successful to date. 2 refs., 26 figs., 3 tabs

  8. A novel minimal invasive mouse model of extracorporeal circulation.

    Science.gov (United States)

    Luo, Shuhua; Tang, Menglin; Du, Lei; Gong, Lina; Xu, Jin; Chen, Youwen; Wang, Yabo; Lin, Ke; An, Qi

    2015-01-01

    Extracorporeal circulation (ECC) is necessary for conventional cardiac surgery and life support, but it often triggers systemic inflammation that can significantly damage tissue. Studies of ECC have been limited to large animals because of the complexity of the surgical procedures involved, which has hampered detailed understanding of ECC-induced injury. Here we describe a minimally invasive mouse model of ECC that may allow more extensive mechanistic studies. The right carotid artery and external jugular vein of anesthetized adult male C57BL/6 mice were cannulated to allow blood flow through a 1/32-inch external tube. All animals (n = 20) survived 30 min ECC and subsequent 60 min observation. Blood analysis after ECC showed significant increases in levels of tumor necrosis factor α, interleukin-6, and neutrophil elastase in plasma, lung, and renal tissues, as well as increases in plasma creatinine and cystatin C and decreases in the oxygenation index. Histopathology showed that ECC induced the expected lung inflammation, which included alveolar congestion, hemorrhage, neutrophil infiltration, and alveolar wall thickening; in renal tissue, ECC induced intracytoplasmic vacuolization, acute tubular necrosis, and epithelial swelling. Our results suggest that this novel, minimally invasive mouse model can recapitulate many of the clinical features of ECC-induced systemic inflammatory response and organ injury.

  9. A Novel Minimal Invasive Mouse Model of Extracorporeal Circulation

    Directory of Open Access Journals (Sweden)

    Shuhua Luo

    2015-01-01

    Full Text Available Extracorporeal circulation (ECC is necessary for conventional cardiac surgery and life support, but it often triggers systemic inflammation that can significantly damage tissue. Studies of ECC have been limited to large animals because of the complexity of the surgical procedures involved, which has hampered detailed understanding of ECC-induced injury. Here we describe a minimally invasive mouse model of ECC that may allow more extensive mechanistic studies. The right carotid artery and external jugular vein of anesthetized adult male C57BL/6 mice were cannulated to allow blood flow through a 1/32-inch external tube. All animals (n=20 survived 30 min ECC and subsequent 60 min observation. Blood analysis after ECC showed significant increases in levels of tumor necrosis factor α, interleukin-6, and neutrophil elastase in plasma, lung, and renal tissues, as well as increases in plasma creatinine and cystatin C and decreases in the oxygenation index. Histopathology showed that ECC induced the expected lung inflammation, which included alveolar congestion, hemorrhage, neutrophil infiltration, and alveolar wall thickening; in renal tissue, ECC induced intracytoplasmic vacuolization, acute tubular necrosis, and epithelial swelling. Our results suggest that this novel, minimally invasive mouse model can recapitulate many of the clinical features of ECC-induced systemic inflammatory response and organ injury.

  10. Social work and artefacts

    DEFF Research Database (Denmark)

    Høybye-Mortensen, Line Matilde

    2015-01-01

    Socialarbejderes brug af artefakter—altså objekter såsom papir, computer og plastikmodeller—i klientrelationer bliver sjældent undersøgt. Som oftest fokuserer forskningen på interpersonelle relationer, målgrupper, professionelle kompetencer og indsatstyper samt metoder i socialt arbejde. I en und...

  11. 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.

  12. 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.)

  13. 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.)

  14. 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.)

  15. 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)

  16. 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.

  17. The reports of thick discs' deaths are greatly exaggerated. Thick discs are NOT artefacts caused by diffuse scattered light

    Science.gov (United States)

    Comerón, S.; Salo, H.; Knapen, J. H.

    2018-02-01

    Recent studies have made the community aware of the importance of accounting for scattered light when examining low-surface-brightness galaxy features such as thick discs. In our past studies of the thick discs of edge-on galaxies in the Spitzer Survey of Stellar Structure in Galaxies - the S4G - we modelled the point spread function as a Gaussian. In this paper we re-examine our results using a revised point spread function model that accounts for extended wings out to more than 2\\farcm5. We study the 3.6 μm images of 141 edge-on galaxies from the S4G and its early-type galaxy extension. Thus, we more than double the samples examined in our past studies. We decompose the surface-brightness profiles of the galaxies perpendicular to their mid-planes assuming that discs are made of two stellar discs in hydrostatic equilibrium. We decompose the axial surface-brightness profiles of galaxies to model the central mass concentration - described by a Sérsic function - and the disc - described by a broken exponential disc seen edge-on. Our improved treatment fully confirms the ubiquitous occurrence of thick discs. The main difference between our current fits and those presented in our previous papers is that now the scattered light from the thin disc dominates the surface brightness at levels below μ 26 mag arcsec-2. We stress that those extended thin disc tails are not physical, but pure scattered light. This change, however, does not drastically affect any of our previously presented results: 1) Thick discs are nearly ubiquitous. They are not an artefact caused by scattered light as has been suggested elsewhere. 2) Thick discs have masses comparable to those of thin discs in low-mass galaxies - with circular velocities vc< 120 km s-1 - whereas they are typically less massive than the thin discs in high-mass galaxies. 3) Thick discs and central mass concentrations seem to have formed at the same epoch from a common material reservoir. 4) Approximately 50% of the up

  18. A solid tissue phantom for photon migration studies

    International Nuclear Information System (INIS)

    Cubeddu, Rinaldo; Pifferi, Antonio; Taroni, Paola; Torricelli, Alessandro; Valentini, Gianluca

    1997-01-01

    A solid tissue phantom made of agar, Intralipid and black ink is described and characterized. The preparation procedure is fast and easily implemented with standard laboratory equipment. An instrumentation for time-resolved transmittance measurements was used to determine the optical properties of the phantom. The absorption and the reduced scattering coefficients are linear with the ink and Intralipid concentrations, respectively. A systematic decrease of the reduced scattering coefficient dependent on the agar content is observed, but can easily be managed. The phantom is highly homogeneous and shows good repeatability among different preparations. Moreover, agar inclusions can be easily embedded in either solid or liquid matrixes, and no artefacts are caused by the solid - solid or solid - liquid interfaces. This allows one to produce reliable and realistic inhomogeneous phantoms with known optical properties, particularly interesting for studies on optical imaging through turbid media. (author)

  19. 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

  20. 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)