Data Acquisition Phase Research Articles

A flexible framework for managing temporal clinical trial data

Clinical trials are processes that produce large volumes of complex data, with inherent temporal requirements, since the state of patients evolves during the trials, and the data acquisition phase itself needs to be monitored. Additionally, since the requirements for all clinical trials have a significant common portion, it is desirable to capture these common requirements in a generalised framework, which will be instantiated for each specific trial by supplementing the trial-specific requirements. In this paper, we present an integral approach to clinical trial management, using a temporal object-oriented methodology to capture and model the requirements, a temporal OODBMS for data storage and a generalised template application, through which trial-specific applications may be generated.

Methodologies for analyzing intrinsic and required DEM accuracy for hydrological applications of flash floods

For extreme events like flash floods, infiltration is considered to be negligible, and the morphology of the watershed is considered to be the most significant factor. Thus, digital elevation models (DEMs) are the most efficient data source to define the catchment surface. To determine if the DEM is adapted, it is essential to analyze both the intrinsic accuracy and the required accuracy. In this paper we propose two complementary methodologies to analyze and evaluate these two kinds of DEM accuracy that relate to the hydrological applications to flash floods. The first methodology relates to the intrinsic accuracy: a diagnostic method analyzes the accuracy and stability of the extracted hydrographic network at catchment scale. To obtain correct positioning of the channels, results show the strong influence of the topographic context and the need for associating extra data on rivers, especially in flat areas. The impact of accuracy is evaluated through a scheme based on DEM grid rotation. A step by step and iterative process gives a fuzzy evaluation of the hydrographic network. These techniques also highlight the strong scale dependence of the extracted network. The second methodology relates to the required accuracy. To analyze the sensitivity to the DEM accuracy, we propose an approach by comparing the results of hydraulic models obtained from a "real" description of the river topography and from this description distorted by a numerical noise characterizing the lack of accuracy of the DEM. The impact of this noise on the overflows on the major bed is analyzed. The results show that the accuracy required by the thematicians is often greater than that strictly required by modeling, which opens interesting prospects to reduce the phases of data acquisition.

Skin temperature changes induced by strong static magnetic field exposure.

High intensity static magnetic fields, when applied to the whole body of the anesthetized rat, have previously been reported to decrease skin temperature. The hypothesis of the present study was that in diamagnetic water, molecules in the air play significant roles in the mechanism of skin temperature decrease. We used a horizontal cylindrical superconducting magnet. The magnet produced 8 T at its center. A thermistor probe was inserted in a subcutaneous pocket of the anesthetized rats to measure skin temperature. Animals (n=10) were placed in an open plastic holder in which the ambient air was free to move in any direction (group I). Animals (n=10) were placed in a closed holder in which the air circulation toward the direction of weak magnetic field was restricted (group II). Each holder was connected to a hydrometer to measure humidity around the animal in the holder. The data acquisition phase consisted of a 5 min baseline interval, followed by inserting the animal together with the holder into the center of the magnet bore for a 5 min exposure and a 5 min postexposure period outside the bore. In group I, skin temperature and humidity around the animal significantly decreased during exposure, followed by recovery after exposure. In group II, skin temperature and humidity did not decrease during the measurement. The skin temperature decrease was closely related to the decrease in humidity around the body of the animal in the holder, and the changes were completely blocked by restricting the air circulation in the direction of the bore entrance. Possible mechanisms responsible for the decrease in skin temperature may be associated with magnetically induced movement of water vapor at the skin surface, leading to skin temperature decrease.

Observing the Antarctic Ice Sheet Using the RADARSAT-1 Synthetic Aperture Radar

This paper discusses the RADARSAT-1 Antarctic Mapping Project (RAMP). RAMP is a collaboration between NASA and the Canadian Space Agency (CSA) to map Antarctica using the RADARSAT -1 synthetic aperture radar. The project was conducted in two parts. The first part, which had the data acquisition phase in 1997, resulted in the first high-resolution radar map of Antarctica. The second part, which occurred in 2000, remapped the continent below 80°S Latitude and is now using interferometric repeat-pass observations to compute glacier surface velocities. Project goals and objectives are reviewed here along with several science highlights. These highlights include observations of ice sheet margin change using both RAMP and historical data sets and the derivation of surface velocities on an East Antarctic outlet glacier using interferometric data collected in 2000.

Mobile robot mapping in populated environments

The problem of learning maps with mobile robots has received considerable attention over the past years. Most of the approaches, however, assume that the environment is static during the data-acquisition phase. In this paper we consider the problem of creating maps with mobile robots in populated environments. Our approach uses a probabilistic method to track multiple people and to incorporate the estimates of the tracking technique into the mapping process. The resulting maps are more accurate since the number of spurious objects is reduced and since the robustness of range registration is improved. Our approach has been implemented and tested on real robots in indoor and outdoor scenarios. We present several experiments illustrating the capabilities of our approach to generate accurate two- and three-dimensional maps.

A general-purpose Java tool for action dispatching and supervision in nuclear fusion experiments

In nuclear fusion experiments, the plasma discharge requires a preparation sequence followed by a data acquisition phase. During these phases, the control and data acquisition system is required to carry out a sequence of operations for set up of the various devices, data readout, and on-line computation. An action dispatcher tool must comply with several requirements such as the support for a distributed and heterogeneous environment, a comprehensive user interface for the supervision of the whole sequence, and the need for web-based support. The paper describes the architecture of a general-purpose Java-based tool for action dispatching. The use of the platform-independent Java framework, combined with the generic approach in the architecture definition, satisfies the above requirements. The Java framework has been chosen for the implementation because of its platform-independence, network, and multithreading support. The architecture of the tool has been kept quite generic, thus making the tool adaptable to a variety of operating environments with minimal changes in the application code.

A portable instrument for scintigraphic recording of blood volume shifts

A portable scintigraphic instrument for continuous recording of intravascular blood shift at several sites was developed. It consists of several (up to six) miniature scintillation detectors with integrated preamplifier, their relevant electronic chains (gaussian shaping amplifier and threshold discriminator), six 16-bit counters, a large memory and a microcontroller that generates the time base, reads the counters and transfers the data to the memory. The activity data that correspond to intravascular volume shifts can be collected for more than 24 hours and then transferred to a computer for analysis. The small size and weight of the instrument and the absence of any data link to the computer in the data acquisition phase make it possible to apply the scintigraphic technique during common daily activities.

Geophysical survey planning for the Dounreay and Sellafield geological investigations

Abstract Between 1989 and 1994 two large engineering site investigation projects in the United Kingdom at Dounreay in Caithness and the Sellafield area in West Cumbria were carried out for the study of possible locations for a deep underground facility for low-level and intermediate-level radioactive waste. In the geophysical domain, management of a diverse range of specialist services required initial desk studies, survey design, acquisition and processing supervision, interpretation, reporting and archiving. Document creation (design intent memoranda, tenders and contracts, Quality Assurance, technical reviews and reports) together with technical control during the data acquisition phase was followed by involvement in the interpretation of the results. A range of geophysical methods were employed including onshore and offshore seismic reflection with associated gravity acquisition, transition zone seismic, airborne geophysics (utilizing spectroscopy, magnetics and VLF) and ground electromagnetic surveys. At the peak of activity, responsibility for the geophysical operations involved the simultaneous management of five field crews - two land seismic with some gravity, one marine seismic with gravity and two helicopters acquiring airborne data - as well as ongoing VSP in the deep, fully cored, boreholes. Some of the work undertaken for each of these disciplines will be described in relation to both projects.

NASA B-757 HIRF test series low power on-the-ground tests

The data acquisition phase of a program intended to provide data for the validation of computational, analytical and experimental techniques for the assessment of electromagnetic effects in commercial transports, for the checkout of instrumentation for following test programs, and for the support of protection engineering of airborne systems has been completed. The initial phase involved on-the-ground electromagnetic measurements. Measurements were made of the fields coupled into the aircraft interior and signals induced in select structures and equipment under controlled illumination by RF fields. A characterization of the ground was also performed to permit ground effects to be included in forthcoming computer modeling exercises. A series of fly-by experiments were conducted in early 1995 in which the NASA B-757 was flown in the vicinity of a Voice of America station (/spl sim/25 MHz), a fixed transmitter driving a log periodic array (172 MHz), and an ASRF radar at Wallops Island (430 MHz). In this paper, the overall test program is defined with particular attention to the on-the-ground portion. The test rationale, test layout, and samples of the data are described. Samples of some inferences from the data that will be useful in protection engineering and EM effects mitigation will also be presented.

MR image classification algorithms for neurosurgical and stereotactic radiosurgical trajectory planning and volumetric analysis

Neurosurgical and stereotactic radiosurgical trajectory planning involves a phase of image data acquisition followed by localization of tissues to be avoided or crossed during the procedure. Success of the procedure is often assessed during follow-up by performing volumetric analysis of tissues of interest. Both localization and volumetric analysis can be facilitated by classifying the input data into different tissue types. This study compares classification results based on four different input image data: (1) MR data obtained with one TR and TE parameter combination, (2) MR data acquired with eight combinations of TR and TE parameters, (3) input data compressed into four principal components, and (4) the input data (3) together with first- and second-order texture features. The algorithms (a) to reduce the dimensionality using principal components, (b) to generate texture features, (c) to determine feature usefulness in classification using the Wilk's lambda criterion, and (d) to classify the input set are described. Classification results are found to be poor for input data 1 and much improved (qualitatively and quantatively) for input data 2. Input data 3 produces classification results (quantitatively and qualitatively) similar to that of 2. Input data 4 is found to produce quantitative results similar to those of 2 and 3, but the qualitative results show enhanced classification of some tissues and distortion of others.

The polar phase response property of monopolar ECG voltages using a Computer-Aided Design and Drafting (CAD)-based data acquisition system

The present paper discusses a Computer-Aided Design and Drafting (CAD) based data acquisition and polar phase response study of the ECG. The scalar ECG does not show vector properties although such properties are embedded in it. In the present paper the polar phase response property of monopolar chest lead (V1 to V6) ECG voltages has been studied. A software tool has been used to evaluate the relative phase response of ECG voltages. The data acquisition of monopolar ECG records of chest leads V1 to V6 from the chart recorder has been done with the help of the AutoCAD application package. The spin harmonic constituents of ECG voltages are evaluated at each harmonic plane and the polar phase responses are studied at each plane. Some interesting results have been observed in some typical cases which are discussed in the paper.

Hipparcos: Revised mission overview

The Hipparcos astrometry satellite was launched on 8 August 1989, and after spacecraft and payload commissioning, commenced the routine data acquisition phase on 26 November 1989. Having failed to reach its planned geostationary orbit, major revisions in the mission operations had to be performed, although the impact on the final mission accuracies now appears to be less severe than originally foreseen. The final astrometric accuracies attainable by the Hipparcos mission will be influenced by the spacecraft and payload performances on the one hand, and by the data reductions procedures on the other. This paper addresses the former aspects, and will cover the overall mission performances (expected lifetime, useful fraction of the time for which useful scientific data is acquired, etc) as well as some details of the spacecraft and payload performances. The in-orbit calibration and environmental results (thermal environment, background levels, geometric, photometric and optical performances) and key operational features (real-time attitude determination quality, etc) will be presented. The subsequent stages of the data processing and final elements of the accuracy assessment are presented in accompanying contributions.

The Hipparcos Mission: Will it be a Scientific Success?

AbstractThe Hipparcos astrometry satellite was launched on 8 August 1989, and after spacecraft and payload commissioning, commenced the routine data acquisition phase on 26 November 1989. Having failed to reach its planned geostationary orbit, major revisions in the mission operations were made, and the post-launch expectations of the mission were strongly degraded with respect to the original goals - principally due to the greatly reduced observational efficiency (caused by the lack of ground station coverage) and the anticipated degraded mission lifetime (as a result of the high-energy particle degradation of the solar arrays in the geostationary transfer orbit).The final astrometric accuracies attainable by the Hipparcos mission will be influenced by the spacecraft and payload performances on the one hand, and by fraction of useful data and mission lifetime on the other. It will be shown that the elemental observational measurements correspond very closely to the predictions, and the data recovery fraction now stands at around 60–70 per cent, so that the ultimate scientific value of the Hipparcos results will be tied directly to the satellite lifetime. A measurement duration of at least 18 months is mandatory if the astrometric parameters (parallaxes and proper motions) are to be decoupled through the data reductions procedures. A somewhat longer lifetime (2.5–3 years) is necessary in order to reduce the errors on the astrometric parameters to the astrophysically-significant accuracies of around 2 milli-arcsec.It will be shown that the present indications of the satellite performances, and the significant progress already made in the data reductions, indicate that the difficulties of the ‘revised’ Hipparcos mission have been largely overcome, and that these target accuracies could still be achievable.

Thought for Food: Suggestions for a systematised approach to emergency food distribution operations

The following paper is a synopsis of a longer report, under the same name, aimed at the people responsible for implementing relief food operations. The report attempts to fill a perceived need for a manual covering the organisation of relief operations from planning to evaluation stages. Following the initial planning phase, the distribution of relief food can be viewed as a logistics operation sandwiched between two phases of data acquisition - one before the distribution of relief to targetted destinations, and the other after the distribution, to assess its efficacy and to identify problems.

A unified model for data acquisition and decision making

In this paper we present a model for decision making employing both the concepts of expected utility and belief functions. The situation modeled is that of a decision maker trying to select a single course of action from a finite set of possible courses of action. Although this selection is the major decision, the decision maker is also confronted with many preliminary decisions such as which data sources to access to obtain pertinent information and how to evaluate the mforma tion received. The proposed model partitions the total decision making problem into two interlocking sub-processes—the data acquisi tion process and the final decision process which is based on an elimination procedure. Decisions in the data acquisition phase employ a rationale based on expected utility, while the criterion upon which the final decision is made is based on belief functions. The application of this model is illustrated by two related examples which are discussed in some detail. The approach proposed in this paper is in a sense a mathematical structunng of the type of reasoning intuitively followed by an intelligent human decision maker when faced with a single important decision. The mathematical modeling of such processes is becoming increasingly important as the role of the computer in modem decision making continues to grow.

Data quality: The Achilles heel of end-user computing

Data quality is an important factor in the success or failure of end-user developed information systems. However, experience shows that in some practical situations data of poor quality are the norm rather than the exception. The evidence in this study demonstrates that exploratory statistical techniques can significantly improve data quality during all phases of data acquisition. More importantly, however, these techniques are especially crucial to quality control and to the validation of data already collected.

Data acquisition system for maximum-likelihood analysis of electron microscopic autoradiographs.

EMAMAP is a program for the data acquisition phase of maximum-likelihood analysis of electron microscope autoradiographs. This program is written in C and has been implemented on a Masscomp MC-500 which supports a graphics processor and a digitizing tablet. The image analysis is automated at a low level: the program operator outlines the edges of the structures of interest using the digitizing tablet, while contiguous regions formed by closed contours are automatically filled by the software. The resulting image is compressed for efficient storage by a quadtree encoding technique for which data compression ratios of greater than 25:1 have been achieved. In practical terms, this implies that the data from a typical experiment of 50 autoradiographs could be stored on a single floppy disk. The system is currently in use for acquiring actual biological experimental data.

Total digital radiology department: spatial resolution requirements.

The minimum spatial resolution required for a total digital radiology department has yet to be defined. A pilot study designed to provide this information was performed. Abnormal and normal radiographic images of children were digitized and redisplayed on film at spatial resolutions of 5.0, 2.5, 1.25, and 0.625 lp/mm. These resolutions are comparable to a digital display of a 14 X 14 in. chest image having pixel elements of 4096 X 4096, 2048 X 2048, 1024 X 1024, and 512 X 512, respectively. Contrast resolution was maintained at 12 bits or 4096 gray levels. The three phases of data acquisition were (1) the standard analysis of receiver operating characteristics, (2) a checklist evaluation of the "seeability" of important structures, and (3) a comparison of all resolutions and a discernment of usability. Fifteen radiologists participated in the study. On the basis of the pediatric cases used, the results showed that the needed spatial resolution for a total digital radiology department may be around 2.5 lp/mm (2048 X 2048). Checklist data on seeability of structures and comparisons of all resolutions give information on specific changes that are occurring as the resolution is decreased, and, when included with the receiver-operating-characteristic data, they become a major component in developing a resolution standard. The finding that 2.5 lp/mm is the required spatial resolution makes construction of a total digital radiology department possible with present state-of-the-art technology.

Geotechnical and groundwater geophysics

Because of a change in emphasis from power plant siting to projects principally involving process and facility monitoring and certification of existing structures (dams, pipelines, etc.), geotechnical and groundwater geophysics is in quite a healthy state after some lean years following the demise of nuclear energy construction projects. The orders‐of‐magnitude jump in the computational capability of geophysicists working in these fields has overshadowed advances in instrumentation (e.g., digital enhancement seismographs), field methods (e.g., cross‐borehole EM), and interpretive procedures. The advent of powerful, affordable microcomputers has enabled expansion into applications demanding finer resolution and quicker turnaround of results. As a result, shallow seismic reflection, seismic and electromagnetic geotomography, and the complementary use of surface and borehole electrical resistivity and seismic data will soon be common if not dominant methods in geotechnical and groundwater investigations. Future trends point to increased emphasis on environmental and economic issues (e.g., toxic wastes or the stability of underground petroleum storage facilities), cross‐fertilization with petroleum reservoir engineering (process monitoring and detailed reservoir description), and greater involvement of computers in the planning, data acquisition, and interpretive phases of our projects. As computers take over more of the data collection‐processing‐interpretation sequence, one of the greatest challenges facing us will be to define the proper role of humans and to use the new technology wisely.

Microcomputers in social psychophysiological research: An overview

Microcomputer systems have become commonplace in the psychophysiological laboratory during the past 5 years and are currently used in all phases of data acquisition, experimental control, and data analysis. In the past year, however, advances in microprocessor technology and scientific software have greatly extended the capabilities of these desk-top systems. Small laboratories now can afford an integrated laboratory microcomputer system and both the high-fidelity data acquisition hardware and the sophisticated analysis capabilities traditionally found in large minicomputers. We briefly describe the demands that social psychophysiological research can place on computer systems, the system presently employed in our laboratory, and a system being installed to overcome limitations on sampling rate, sampling periods, and waveform analysis.