Generation Of Artifacts Research Articles

Aircraft-Based Aerosol Sampling in Clouds: Performance Characterization of Flow-Restriction Aerosol Inlets

AbstractInteraction of liquid cloud droplets and ice particles with aircraft aerosol inlets can result in the generation of a large number of secondary particles and contaminate aerosol measurements. Recent studies have shown that a sampler designed with a perpendicular subsampling tube located within a flow-through conduit (i.e., a flow-restriction inlet) was best suited for in-cloud sampling. Analysis of field data obtained from different flow-restriction inlets shows that their critical cloud droplet breakup diameters are strongly dependent on design details and operating conditions. Using computational fluid dynamics (CFD) simulations, in-cloud sampling performance of a selected inlet can be predicted reasonably accurately for known operating conditions. To understand the relation between inlet design parameters and its sampling performance, however, CFD calculations are impractical. Here, using a simple, representative one-dimensional velocity profile and a validated empirical droplet breakup criteria, a parametric study is conducted to understand the relationship between different inlet design features and operating conditions on its critical breakup diameters. The results of this study suggest that an optimal inlet for in-cloud aerosol sampling should have a combination of a restriction nozzle at the aft end of the flow-through conduit to minimize wall-impaction shatter artifacts and a blunt leading edge to minimize shatter artifact generation from the aerodynamic breakup of cloud droplets. Inlets for in-cloud aerosol sampling from aircraft will, therefore, differ significantly in design from those used for clear-air aerosol sampling.

Automatic construction of Fuzzy Inference Systems for computerized clinical guidelines and protocols

Clinical guidelines and protocols (CGPs) are standard documents with the aim of helping practitioners in their daily work. Their computerization has received much attention in recent years, but it still presents some problems, mainly due to the low sustainability and low adaptability to changes (both in knowledge and technology) of the computerized CGPs. This paper presents an approach to an easy and automatic creation of Fuzzy Inference Systems (FISs), which are suitable for the computerized interpretation of differential diagnoses. The proposed FIS development process is based on applying Model-Driven Software Engineering techniques: automatic generation of computer artefacts and separation of concerns. The process focuses on the separation of roles during the design stage: domain experts use a basic editor that allows them to define the categories and factors that will be involved in the FIS in natural language, while knowledge engineers at a later stage refine these elements using a more advanced editor. The whole system has been tested by automatically generating two FISs that have been included in a computerized CGP for the diagnosis of a rare disease called hyperammonemia. This CGP has been validated and it is currently in use.

An empirical comparison of model-based and capture and replay approaches for performance testing

A variety of testing tools has been developed to support and automate the software testing activity. Some of them may use different techniques such as Model-based Testing (MBT) or Capture and Replay (CR). Model-based Testing is a technique for automatic generation of testing artifacts based on software models. One of the main benefits of using MBT is related to the easiness of maintaining models over code; hence, it is likely that using models as a source for automatic generation of scripts requires less effort and reduces the number of faults. Otherwise, CR-based tools basically record the user interaction with the System Under Test (SUT) and then playback the recorded test. This paper presents our effort on setting up and running an experimental study performed in order to evaluate the effort to use MBT and CR-based tools to generate performance scripts. Thus, we apply an MBT and a CR approaches for the purpose of evaluation with respect to the effort to generate scripts and scenarios from the perspective of the performance testers and the performance test engineers in the context of undergraduates, M.Sc. and Ph.D. students, performance testers and performance test engineers for the generation of performance test scripts and scenarios. Our results indicate that, for simple testing tasks, the effort of using a CR-based tool was lower than using an MBT tool, but as the complexity or size of the activities of the testing tasks increases, the advantage of using MBT increased significantly.

Generation of realistic thigh soft tissue artefacts as a function of hip and knee kinematics

INTRODUCTION and AIM The movement of skin markers relative to the underlying bone (soft tissue artefact, STA) and its compensation is regarded as the major problem in human movement analysis using stereophotogrammetry. Based on a quasilinear relationship of the STAs with the closest joint angles [1, 2, 3], this study aimed at devising and assessing a model able to generate realistic thigh STAs for both simulation and compensation purposes during multiarticular movements. Model feasibility was assessed in-vivo during running using both skin and pin markers.

Generation of chest compression artefacts on the ECG and the thoracic impedance signals in a manikin model

s / Resuscitation 85S (2014) S15–S121 S107 Results: Eighty scenarios and 80 teams of 4 PCP were evaluated. All teams identified the situation and severity. However,most of them had some problem with treatment: 90% administrated oxygen and placed pulse-oximeter in first 2min, but only 50% proceeded to manually open the airway. In 97% of cases, epinephrine was the initial drug, and it was administered in the first 10min; however 93% of groups administered epinephrine by subcutaneous route. 90% of groups administered two epinephrine doses, 60% three and 30% four doses. 80% of groups obtained a venous access, and 20% an intraosseous route. 97% of groups administered fluid bolus, and 80% corticosteroids. Conclusion: PCP identify the severity of a simulated anaphylactic reaction. However, they need to improve their capability to perform a prompt and sequential treatment, according to evidence-based recommendations. Training programs in pediatric emergencies should reinforce hands on sessions; in this sense, advanced simulation can be a tool to be considered. http://dx.doi.org/10.1016/j.resuscitation.2014.03.264

Towards an automation of the mutation analysis dedicated to model transformation

SummaryA benefit of model‐driven engineering relies on the automatic generation of artefacts from high‐level models through intermediary levels using model transformations. In such a process, the input must be well designed, and the model transformations should be trustworthy. Because of the specificities of models and transformations, classical software test techniques have to be adapted. Among these techniques, mutation analysis has been ported, and a set of mutation operators has been defined. However, it currently requires considerable manual work and suffers from the test data set improvement activity. This activity is a difficult and time‐consuming job and reduces the benefits of the mutation analysis. This paper addresses the test data set improvement activity. Model transformation traceability in conjunction with a model of mutation operators and a dedicated algorithm allow to automatically or semi‐automatically produce improved test models. The approach is validated and illustrated in two case studies written in Kermeta.Copyright © 2014 John Wiley & Sons, Ltd.

The finite element method for micro-scale modeling of ultrasound propagation in cancellous bone

Quantitative ultrasound for bone assessment is based on the correlations between ultrasonic parameters and the properties (mechanical and physical) of cancellous bone. To elucidate the correlations, understanding the physics of ultrasound in cancellous bone is demanded. Micro-scale modeling of ultrasound propagation in cancellous bone using the finite-difference time-domain (FDTD) method has been so far utilized as one of the approaches in this regard. However, the FDTD method accompanies two disadvantages: staircase sampling of cancellous bone by finite difference grids leads to generation of wave artifacts at the solid–fluid interface inside the bone; additionally, this method cannot explicitly satisfy the needed perfect-slip conditions at the interface. To overcome these disadvantages, the finite element method (FEM) is proposed in this study. Three-dimensional finite element models of six water-saturated cancellous bone samples with different bone volume were created. The values of speed of sound (SOS) and broadband ultrasound attenuation (BUA) were calculated through the finite element simulations of ultrasound propagation in each sample. Comparing the results with other experimental and simulation studies demonstrated the capabilities of the FEM for micro-scale modeling of ultrasound in water-saturated cancellous bone.

Imaging Artifacts During Transesophageal Echocardiography

Imaging Artifacts During Transesophageal Echocardiography

Rhythms of Learning -- Radical and Incremental Innovation Projects and Problem-solving in the Automotive Industry

This paper studies effects of interaction and communication patterns on learning in radical and incremental New Product Development (NPD) projects. It presents results of a multiple longitudinal case study of project meetings and data exchange along a technological transition path in four sequential car development projects. To gain in depth insights, data were analyzed on project level and on problem-solving level by means of a mixed-method approach. We contribute to the literature on organizational learning and problem-solving in NPD by deriving propositions based on three rhythmic patterns identified. First, we identify that effective project-to-project learning requires communication and interaction overlap, and is moderated by project newness. Second, successful projects form a wave-shaped rhythm of communication defined by changing amplitudes and frequencies. In effective learning, communication follows a decaying oscillation. Third, we observe that interaction is best described as an s-shaped curve, reflecting phases of high and low intense artifact generation. In combination, identified patterns serve as reference values to evaluate project performance and allow managerial intervention.

Limiting degradation of reactive antibody drug conjugate intermediates in HPLC method development

The development of an accurate HPLC method for a reactive linker drug intermediate for antibody drug conjugates (ADCs) is challenging as the linker drug is designed to be reactive. This reactivity can lead to the generation of artifact peaks in the chromatograms and deliver inaccurate impurity content results. In this study, the linker drug contains an amine reactive tetrafluorophenyl (TFP) ester that readily undergoes hydrolysis and internal succinimide cyclization in aqueous solution. While complete elimination of the on-column degradation was nearly impossible, optimization of the critical chromatography conditions guided by chemical kinetics minimizes the degree of on-column degradation enabling an accurate assay and purity method for this reactive linker drug intermediate. Kinetics of the linker drug reactions were studied in different solution pHs and temperatures while the reaction rates were used to guide the selection of the optimum diluent, mobile phase pH, and column temperature to minimize the on-column degradation. An UHPLC column was used to achieve fast analysis to further reduce the degree of on-column degradation. The actual amount of on-column degradation of the final HPLC method was determined to be <0.1%, lower than the ICH reporting limit of, therefore demonstrate the effectiveness of the strategy.

The struggle to find reliable results in exome sequencing data: filtering out Mendelian errors

Next Generation Sequencing studies generate a large quantity of genetic data in a relatively cost and time efficient manner and provide an unprecedented opportunity to identify candidate causative variants that lead to disease phenotypes. A challenge to these studies is the generation of sequencing artifacts by current technologies. To identify and characterize the properties that distinguish false positive variants from true variants, we sequenced a child and both parents (one trio) using DNA isolated from three sources (blood, buccal cells, and saliva). The trio strategy allowed us to identify variants in the proband that could not have been inherited from the parents (Mendelian errors) and would most likely indicate sequencing artifacts. Quality control measurements were examined and three measurements were found to identify the greatest number of Mendelian errors. These included read depth, genotype quality score, and alternate allele ratio. Filtering the variants on these measurements removed ~95% of the Mendelian errors while retaining 80% of the called variants. These filters were applied independently. After filtering, the concordance between identical samples isolated from different sources was 99.99% as compared to 87% before filtering. This high concordance suggests that different sources of DNA can be used in trio studies without affecting the ability to identify causative polymorphisms. To facilitate analysis of next generation sequencing data, we developed the Cincinnati Analytical Suite for Sequencing Informatics (CASSI) to store sequencing files, metadata (eg. relatedness information), file versioning, data filtering, variant annotation, and identify candidate causative polymorphisms that follow either de novo, rare recessive homozygous or compound heterozygous inheritance models. We conclude the data cleaning process improves the signal to noise ratio in terms of variants and facilitates the identification of candidate disease causative polymorphisms.

Delta-oriented model-based integration testing of large-scale systems

Software architecture specifications are of growing importance for coping with the complexity of large-scale systems. They provide an abstract view on the high-level structural system entities together with their explicit dependencies and build the basis for ensuring behavioral conformance of component implementations and interactions, e.g., using model-based integration testing. The increasing inherent diversity of such large-scale variant-rich systems further complicates quality assurance. In this article, we present a combination of architecture-driven model-based testing principles and regression-inspired testing strategies for efficient, yet comprehensive variability-aware conformance testing of variant-rich systems. We propose an integrated delta-oriented architectural test modeling and testing approach for component as well as integration testing that allows the generation and reuse of test artifacts among different system variants. Furthermore, an automated derivation of retesting obligations based on accurate delta-oriented architectural change impact analysis is provided. Based on a formal conceptual framework that guarantees stable test coverage for every system variant, we present a sample implementation of our approach and an evaluation of the validity and efficiency by means of a case study from the automotive domain.

Lunar ground penetrating radar: Minimizing potential data artifacts caused by signal interaction with a rover body

Ground-penetrating radar (GPR) is the leading geophysical candidate technology for future lunar missions aimed at mapping shallow stratigraphy (<5m). The instrument’s exploration depth and resolution capabilities in lunar materials, as well as its small size and lightweight components, make it a very attractive option from both a scientific and engineering perspective. However, the interaction between a GPR signal and the rover body is poorly understood and must be investigated prior to a space mission. In doing so, engineering and survey design strategies should be developed to enhance GPR performance in the context of the scientific question being asked. This paper explores the effects of a rover (simulated with a vertical metal plate) on GPR results for a range of heights above the surface and antenna configurations at two sites: (i) a standard GPR testing site with targets of known position, size, and material properties, and; (ii) a frozen lake for surface reflectivity experiments. Our results demonstrate that the GPR antenna configuration is a key variable dictating instrument design, with the XX polarization considered optimal for minimizing data artifact generation. These findings could thus be used to help guide design requirements for an eventual flight instrument.

Measuring interference of drug-like molecules with the respiratory chain: toward the early identification of mitochondrial uncouplers in lead finding.

The electron transport chain (ETC) couples electron transfer between donors and acceptors with proton transport across the inner mitochondrial membrane. The resulting electrochemical proton gradient is used to generate chemical energy in the form of adenosine triphosphate (ATP). Proton transfer is based on the activity of complex I-V proteins in the ETC. The overall electrical activity of these proteins can be measured by proton transfer using Solid Supported Membrane technology. We tested the activity of complexes I, III, and V in a combined assay, called oxidative phosphorylation assay (oxphos assay), by activating each complex with the corresponding substrate. The oxphos assay was used to test in-house substances from different projects and several drugs currently available on the market that have reported effects on mitochondrial functions. The resulting data were compared to the influence of the respective compounds on mitochondria as determined by oxygen consumption and to data generated with an ATP depletion assay. The comparison shows that the oxidative phosphorylation assay provides both a rapid approach for detecting interaction of compounds with respiratory chain proteins and information on their mode of interaction. Therefore, the oxphos assay is a useful tool to support structure activity relationship studies by allowing early identification of mitotoxicity and for analyzing the outcome of phenotypic screens that are susceptible to the generation of mitotoxicity-related artifacts.

Best current practice for obtaining high quality EEG data during simultaneous FMRI.

Simultaneous EEG-fMRI allows the excellent temporal resolution of EEG to be combined with the high spatial accuracy of fMRI. The data from these two modalities can be combined in a number of ways, but all rely on the acquisition of high quality EEG and fMRI data. EEG data acquired during simultaneous fMRI are affected by several artifacts, including the gradient artefact (due to the changing magnetic field gradients required for fMRI), the pulse artefact (linked to the cardiac cycle) and movement artifacts (resulting from movements in the strong magnetic field of the scanner, and muscle activity). Post-processing methods for successfully correcting the gradient and pulse artifacts require a number of criteria to be satisfied during data acquisition. Minimizing head motion during EEG-fMRI is also imperative for limiting the generation of artifacts. Interactions between the radio frequency (RF) pulses required for MRI and the EEG hardware may occur and can cause heating. This is only a significant risk if safety guidelines are not satisfied. Hardware design and set-up, as well as careful selection of which MR sequences are run with the EEG hardware present must therefore be considered. The above issues highlight the importance of the choice of the experimental protocol employed when performing a simultaneous EEG-fMRI experiment. Based on previous research we describe an optimal experimental set-up. This provides high quality EEG data during simultaneous fMRI when using commercial EEG and fMRI systems, with safety risks to the subject minimized. We demonstrate this set-up in an EEG-fMRI experiment using a simple visual stimulus. However, much more complex stimuli can be used. Here we show the EEG-fMRI set-up using a Brain Products GmbH (Gilching, Germany) MRplus, 32 channel EEG system in conjunction with a Philips Achieva (Best, Netherlands) 3T MR scanner, although many of the techniques are transferable to other systems.

Best Current Practice for Obtaining High Quality EEG Data During Simultaneous fMRI

Simultaneous EEG-fMRI allows the excellent temporal resolution of EEG to be combined with the high spatial accuracy of fMRI. The data from these two modalities can be combined in a number of ways, but all rely on the acquisition of high quality EEG and fMRI data. EEG data acquired during simultaneous fMRI are affected by several artifacts, including the gradient artefact (due to the changing magnetic field gradients required for fMRI), the pulse artefact (linked to the cardiac cycle) and movement artifacts (resulting from movements in the strong magnetic field of the scanner, and muscle activity). Post-processing methods for successfully correcting the gradient and pulse artifacts require a number of criteria to be satisfied during data acquisition. Minimizing head motion during EEG-fMRI is also imperative for limiting the generation of artifacts. Interactions between the radio frequency (RF) pulses required for MRI and the EEG hardware may occur and can cause heating. This is only a significant risk if safety guidelines are not satisfied. Hardware design and set-up, as well as careful selection of which MR sequences are run with the EEG hardware present must therefore be considered. The above issues highlight the importance of the choice of the experimental protocol employed when performing a simultaneous EEG-fMRI experiment. Based on previous research we describe an optimal experimental set-up. This provides high quality EEG data during simultaneous fMRI when using commercial EEG and fMRI systems, with safety risks to the subject minimized. We demonstrate this set-up in an EEG-fMRI experiment using a simple visual stimulus. However, much more complex stimuli can be used. Here we show the EEG-fMRI set-up using a Brain Products GmbH (Gilching, Germany) MRplus, 32 channel EEG system in conjunction with a Philips Achieva (Best, Netherlands) 3T MR scanner, although many of the techniques are transferable to other systems.

Detection of extraction artifacts in the analysis of honey volatiles using comprehensive two-dimensional gas chromatography

Extraction using headspace solid phase microextraction (HS-SPME) coupled to comprehensive two-dimensional gas chromatography with flame ionisation detection (GC×GC–FID) was employed to evaluate the effect of SPME fractionation conditions (heating time and temperature) on the generation of artifacts. The occurrence of artifacts was more pronounced at higher fractionation temperatures and times which caused significant changes in the chromatographic profiles. The identification of the volatile fraction of the honey blend was performed through a two-dimensional gas chromatograph coupled to a mass spectrometer with time of flight analyser (GC×GC–ToFMS) by comparing the first dimension linear temperature programmed retention index (1D-LTPRI) with the peak’s identities provided by the mass spectral similarity search. Several artifacts were found and identified – such as hydroxymethylfurfural, methyl–furone and furfural – and some of them were not previously detected as such in honey samples. These compounds were either the result of hydrolysis or thermal decomposition of components already present in the honey samples. This occurrence was attributed to the increased detectability provided by GC×GC compared to conventional GC. The possible emergence of previously unknown extraction artifacts as a general tendency related use of GC×GC instead of conventional GC is discussed as a result of these observations.

MRI issues for ballistic objects: information obtained at 1.5-, 3- and 7-Tesla

Background contextFew studies exist for magnetic resonance imaging (MRI) issues and ballistics, and there are no studies addressing movement, heating, and artifacts associated with ballistics at 3-tesla (T). Movement because of magnetic field interactions and radiofrequency (RF)-induced heating of retained bullets may injure nearby critical structures. Artifacts may also interfere with the diagnostic use of MRI. PurposeTo investigate these potential hazards of MRI on a sample of bullets and shotgun pellets. Study designLaboratory investigation, ex vivo. MethodsThirty-two different bullets and seven different shotgun pellets, commonly encountered in criminal trauma, were assessed relative to 1.5-, 3-, and 7-T magnetic resonance systems. Magnetic field interactions, including translational attraction and torque, were measured. A representative sample of five bullets were then tested for magnetic field interactions, RF-induced heating, and the generation of artifacts at 3-T. ResultsAt all static magnetic field strengths, non–steel-containing bullets and pellets exhibited no movement, whereas one steel core bullet and two steel pellets exhibited movement in excess of what might be considered safe for patients in MRI at 1.5-, 3- and 7-Tesla. At 3-T, the maximum temperature increase of five bullets tested was 1.7°C versus background heating of 1.5°C. Of five bullets tested for artifacts, those without a steel core exhibited small signal voids, whereas a single steel core bullet exhibited a very large signal void. ConclusionsBallistics made of lead with copper or alloy jackets appear to be safe with respect to MRI-related movement at 1.5-, 3-, and 7-T static magnetic fields, whereas ballistics containing steel may pose a danger if near critical body structures because of strong magnetic field interactions. Temperature increases of selected ballistics during 3-T MRI was not clinically significant, even for the ferromagnetic projectiles. Finally, ballistics containing steel generated larger artifacts when compared with ballistics made of lead with copper and alloy jackets and may impair the diagnostic use of MRI.

The CancerGrid experience: Metadata-based model-driven engineering for clinical trials

The CancerGrid approach to software support for clinical trials is based on two principles: careful curation of semantic metadata about clinical observations, to enable subsequent data integration, and model-driven generation of trial-specific software artefacts from a trial protocol, to streamline the software development process. This paper explains the approach, presents four varied case studies, and discusses the lessons learned.

Generating starting models for seismic refraction tomography with common offset stacks

Common offset refraction (COR) traveltime attributes are derived from multi-fold data with novel adaptations of the generalised reciprocal method (GRM). COR GRM stacks are generated from a refraction equivalent of common midpoint (CMP) gathers, which are computed at each CMP with the COR GRM algorithms. The COR GRM stacks, which generate detailed spatially varying attributes for each layer detected in the near surface region, provide useful starting models for automatic refraction tomography.The spatial resolution of the depth models of the wavepath eikonal traveltime (WET) refraction tomograms obtained with starting models derived with the COR GRM is similar to the WET tomogram obtained with the standard GRM, whereas the COR GRM seismic velocity model is a smoothed version of the standard GRM model. In all cases, the GRM-derived WET tomograms avoid the generation of undetectable artefacts with common implementations of automatic refraction tomography, which can occur with the use of default starting models consisting of smooth vertical velocity gradients and with the need to minimise misfit errors through over-processing.The COR GRM attributes demonstrate that the traveltime data are consistent with minimal penetration within the sub-weathering, representative of uniform seismic velocities, and that the spatial variations in the time model and seismic velocities are more significant than any variations caused by vertical velocity gradients in the sub-weathered zone. However, the occurrence of vertical velocity gradients in the sub-weathering largely remains unresolved because minimal penetration of the first arrivals can occur even with large vertical velocity gradients, such as the hyperbolic velocity function.The WET tomograms generated with the COR GRM time model and seismic velocity attributes are generally very similar visually to the starting models, even though the misfit errors may differ. It is concluded that COR GRM starting models can frequently be a useful alternative to refraction tomography.