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Recruitment of research participants through the Internet.

Despite an increasing amount of Internet research, issues in recruitment for studies in this environment rarely have been discussed. The purpose of this article is to provide some future directions for participant recruitment via the Internet, based on the experiences of recruiting participants for three Internet survey studies. The issues in the recruitment process include those related to low response rates, selected groups of participants, the importance of timing, and potential ethical issues. Based on the discussion of the issues, the following suggestions are proposed for future recruitment through the Internet: use of creative motivation strategies; sensitivity to the gender, ethnicity, and socioeconomic status of potential participants; consideration of the timing of data collection; and sensitivity to potential ethical issues.

Adult↗

Feasibility of studying the effects of using NANDA, NIC, and NOC on nurses' power and children's outcomes.

This was a pilot study with a pretest and posttest design to test the feasibility of conducting large-scale studies of the effects of using computer-based terms from NANDA, NIC, and NOC on nurses' power to help children and children's health outcomes. Four hypotheses were tested with data from 12 public health nurses in school settings and 220 schoolchildren. Group A comprised six nurses who used SNAP Health Center (SNAP 98) software to record health visits with 117 children. Group B comprised six nurses who used the same software and NANDA, NIC, and NOC with 103 children. After use of the software, the power of the 12 nurses to help children significantly increased. For the 220 children, the number of coping strategies significantly increased but there were no changes in the other health outcomes. The hypotheses indicating that Group B nurses and children would have more positive changes than Group A were not supported. Positive and negative elements for large-scale studies were identified.

Adaptation, Psychological↗

Using the nursing process to implement a Y2K computer application.

Because of the coming year 2000, the need was assessed to upgrade the order entry system at many hospitals. At Somerset Medical Center, a training team divided the transition into phases and used a modified version of the nursing process to implement the new program. The entire process required fewer than 6 months and was relatively problem-free. This successful transition was aided by the nursing process, training team, and innovative educational techniques.

Computer User Training↗

Challenges in electronic importing of health data.

The objective of this article is to increase awareness among public health personnel of the complexities involved in integrating existing data systems. This article describes the electronic importing feature of the Centers for Disease Control and Prevention (CDC) software package called staffTRAK-TB, and users' experience with it.

Attitude of Health Personnel↗

Reliability analysis for digital adolescent idiopathic scoliosis measurements.

OBJECTIVE: Analysis of adolescent idiopathic scoliosis (AIS) requires a thorough clinical and radiographic evaluation to completely assess the three-dimensional deformity. Recently, these radiographic parameters have been analyzed for reliability and reproducibility following manual measurements; however, most of these parameters have not been analyzed with regard to digital measurements. The purpose of this study is to determine the intra- and interobserver reliability of common scoliosis radiographic parameters using a digital software measurement program. METHODS: Thirty sets of preoperative (posteroanterior [PA], lateral, and side-bending [SB]) and postoperative (PA and lateral) radiographs were analyzed by three independent observers on two separate occasions using a software measurement program (PhDx, Albuquerque, NM). Coronal measures included main thoracic (MT) and thoracolumbar-lumbar (TL/L) Cobb, SB MT Cobb, MT and TL/L apical vertical translation (AVT), C7 to center sacral vertical line (CSVL), T1 tilt, LIV tilt, disk below lowest instrumented vertebra (LIV), coronal balance, and Risser, whereas sagittal measures included T2-T5, T5-T12, T2-T12, T10-L2, T12-S1, and sagittal balance. Analysis of variance for repeated measures or Cohen three-way kappa correlation coefficient analysis was performed as appropriate to calculate the intra- and interobserver reliability for each parameter. RESULTS: The majority of the radiographic parameters assessed demonstrated good or excellent intra- and interobserver reliability. The relationship of the LIV to the CSVL (intraobserver kappaa = 0.48-0.78, fair to excellent; interobserver kappaa = 0.34-0.41, fair to poor), interobserver measurement of AVT (rho = 0.49-0.73, low to good), Risser grade (intraobserver rho = 0.41-0.97, low to excellent; interobserver rho = 0.60-0.70, fair to good), intraobserver measurement of the angulation of the disk inferior to the LIV (rho = 0.53-0.88, fair to good), apical Nash-Moe vertebral rotation (intraobserver rho = 0.50-0.85, fair to good; interobserver rho = 0.53-0.59, fair), and especially regional thoracic kyphosis from T2 to T5 (intraobserver rho = 0.22-0.65, poor to fair; interobserver rho = 0.33-0.47, low) demonstrated lesser reliability. In general, preoperative measures demonstrated greater reliability than postoperative measures, and coronal angular measures were more reliable than sagittal measures. CONCLUSIONS: Most common radiographic parameters for AIS assessment demonstrated good or excellent reliability for digital measurement and can be recommended for routine clinical and academic use. Preoperative assessments and coronal measures may be more reliable than postoperative and sagittal measurements. The reliability of digital measurements will be increasingly important as digital radiographic viewing becomes commonplace.

Adolescent↗

Carotid wall composition in hypertensive patients after 4-year treatment with lacidipine or atenolol: an echoreflectivity study.

OBJECTIVE: In the European Lacidipine Study on Atherosclerosis (ELSA), against a similar antihypertensive effect, a significantly greater effect of lacidipine was found on carotid intima-media thickness (IMT) progression, indicating a specific anti-atherosclerotic effect of lacidipine. However, not only the extent but also the composition of an atherosclerotic plaque is a determinant of subsequent events. DESIGN AND METHODS: Among the 2334 patients enrolled in ELSA, 420 with 4-year treatment were chosen, videodensitometric analysis of their ultrasound carotid scan was performed and the maximum wall lesion (Tmax) was classified as lipidic, fibrolipidic and fibrotic by means of software previously validated against histology. Of the 420 patients, 244 had scans suitable for videodensitometry. RESULTS: Excellent reproducibility of videodensitometry analysis was found using the Bland-Altman and other methods. At baseline, ELSA hypertensive patients had predominantly fibrolipidic walls (70%), with an echoreflectivity indicating a mean collagen content of 25%. After 4 years of antihypertensive treatment, little change in the frequency distribution of carotid lesions (fibrolipidic 73%) was found, with no significant differences between patients randomized to lacidipine or atenolol. CONCLUSIONS: Our study provides previously unavailable information that carotid wall composition changes to an extremely small extent during 4-year effective blood pressure lowering. With lacidipine, stable composition is associated with a lower IMT progression than with atenolol.

Adult↗

A comparison of the COG and MCNP codes in computational neutron capture therapy modeling, Part I: boron neutron capture therapy models.

The goal of this study was to evaluate the COG Monte Carlo radiation transport code, developed and tested by Lawrence Livermore National Laboratory, for neutron capture therapy related modeling. A boron neutron capture therapy model was analyzed comparing COG calculational results to results from the widely used MCNP4B (Monte Carlo N-Particle) transport code. The approach for computing neutron fluence rate and each dose component relevant in boron neutron capture therapy is described, and calculated values are shown in detail. The differences between the COG and MCNP predictions are qualified and quantified. The differences are generally small and suggest that the COG code can be applied for BNCT research related problems.

Body Burden↗

A model that accounts for the interdependence of extent and severity in the automatic evaluation of myocardial defects.

BACKGROUND: The extent and severity are two important parameters when describing a regional defect in myocardial single-photon emission computed tomography (SPECT) perfusion imaging. Intuitively, these two parameters should be independent of each other, but we have shown in a previous study that there is an interdependence. This interdependence has been investigated in two commercially available analysis programs (AutoQUANT and 4D-MSPECT) using Monte Carlo-simulated SPECT data. METHODS: An anthropomorphic digital computer phantom and a Monte Carlo program were used to generate SPECT data. Several defects of different volumes and lesion activity uptake reductions were simulated and evaluated. Comparison of the measures of extent and severity with their corresponding known values led to the development of a correction model based on least-squares parameter estimation. This model was then applied to a test group consisting of 10 different computer-simulated patients. RESULTS: Our results showed that the interdependence was reduced significantly for most of our test cases after applying the correction method. The application of the correction model to the test group demonstrated that the model was robust with respect to different patient geometries. A further test with projections that simulated a perfect SPECT system revealed that the interdependence between the extent and severity was not caused by the limited spatial resolution of the SPECT system, but rather the inherent design of the algorithms of the analysis programs. CONCLUSIONS: A model has been developed to take into account the interdependence of the extent and severity.

Algorithms↗

Evaluation of left ventricular ejection fraction by the quantitative algorithms QGS, ECTb, LMC and LVGTF using gated myocardial perfusion SPECT: investigation of relative accuracy.

AIM: To compare the quantitative algorithms Emory Cardiac Toolbox (ECTb), quantitative gated SPECT (QGS), layer of maximum counts (LMC), and left ventricular global thickening fraction (LVGTF) using gated myocardial tomography in the calculation of the left ventricular ejection fraction using the regression without truth (RWT) technique. MATERIALS AND METHODS: Seventy-four consecutive patients were included in the study (59 males). All patients underwent stress-rest myocardial perfusion SPECT using Tc-tetrofosmin. Analysis of variance (ANOVA), the paired Student's t-test, the Pearson correlation coefficient and Bland-Altman were used for comparing the methods. The relative accuracy was performed by RWT. RESULTS: ANOVA revealed a significant difference among the methods in calculating the ejection fraction. RWT showed that ECTb and QGS outperformed the other two methods. The ECTb was slightly better than QGS, and LMC was slightly better than LVGTF. QGS and ECTb achieved good correlations in end diastolic volume, end systolic volume and ejection fraction measurements. One-way ANOVA demonstrated that QGS was the only software program affected by the category of the perfusion summed stress score (SSS), P=0.038. The ejection fraction determined by the QGS, ECTb and LVGTF methods correlated significantly with defect size (r=0.545, P<0.0001; r=0.530, P<0.0001; and r=0.419, P<0.0001, respectively), but the LMC method was not significantly correlated (r=0.216, P=0.067). CONCLUSIONS: There was a considerable variation among the quantitative gated SPECT methods in the evaluation of the ejection fraction. RWT revealed that the ECTb and QGS outperformed the other two methods with respect to the bias and precision of the measurements. Pair-wise correlations of the four methods ranged from mild to good with large agreement limits. Results of RWT provided important information in ranking the quantitative gated SPECT methods.

Algorithms↗

Coronary artery calcium scoring: diagnostic accuracy of different software implementations.

PURPOSE: To compare the diagnostic power of different software implementations for the quantification of coronary artery calcium. MATERIALS AND METHODS: Electron beam computed tomography was performed in 109 heart transplant recipients at the same time as catheter coronary angiography and intracoronary ultrasound. Electron beam computed tomography images were analyzed by 3 software packages marketed for the quantification of coronary calcifications using the same software settings, and the resultant calcium scores correlated with the invasive reference methods by Bland-Altman plots and analysis of the receiver operating characteristics. RESULTS: Although all scoring systems displayed close correlations upon regression analysis (r2=0.94-0.99), their ability to detect disease as per the invasive reference method varied significantly in some instances. The area under the ROC curve varied between Az=0.78 and 0.85 for the detection of coronary artery stenosis upon coronary angiography (P=0.05-0.13), and between Az=0.75 and 0.83 for the detection of accelerated intimal proliferation (P=0.03-0.18). CONCLUSIONS: Different software implementations for the quantification of coronary artery calcium load may display diagnostically relevant differences in spite of close direct correlation.

Adolescent↗

Towards performance control on the Grid.

Advances in computational Grid technologies are enabling the development of simulations of complex biological and physical systems. Such simulations can be assembled from separate components--separately deployable computation units of well-defined functionality. Such an assemblage can represent an application composed of interacting simulations or might comprise multiple instances of a simulation executing together, each running with different simulation parameters. However, such assemblages need the ability to cope with heterogeneous and dynamically changing execution environments, particularly where such changes can affect performance. This paper describes the design and implementation of a prototype performance control system (PerCo), which is capable of monitoring the progress of simulations and redeploying them so as to optimize performance. The ability to control performance by redeployment is demonstrated using an assemblage of lattice Boltzmann simulations running with and without control policies. The cost of using PerCo is evaluated and it is shown that PerCo is able to reduce overall execution time.

Benchmarking↗

On the performance of molecular dynamics applications on current high-end systems.

The effective exploitation of current high performance computing (HPC) platforms in molecular simulation relies on the ability of the present generation of parallel molecular dynamics code to make effective utilisation of these platforms and their components, including CPUs and memory. In this paper, we investigate the efficiency and scaling of a series of popular molecular dynamics codes on the UK's national HPC resources, an IBM p690+ cluster and an SGI Altix 3700. Focusing primarily on the AMBER, DL_POLY and NAMD simulation codes, we demonstrate the major performance and scalability advantages that arise through a distributed, rather than a replicated data approach.

Computer Simulation↗

Computing and the cultures of proving.

This article discusses the relationship between mathematical proof and the digital computer from the viewpoint of the 'sociology of proof': that is, an understanding of what kinds of procedures and arguments count for whom, under what circumstances, as proofs. After describing briefly the first instance of litigation focusing on the nature of mathematical proof, the article describes a variety of 'cultures of proving' that are distinguished by whether the proofs they conduct and prefer are (i) mechanized or non-mechanized and (ii) formal proofs or 'rigorous arguments'. Although these 'cultures' mostly coexist peacefully, the occasional attacks from within one on another are of interest in respect to what they reveal about presuppositions and preferences. A variety of factors underpinning the diverse cultures of proving are discussed.

Algorithms↗

The challenge of computer mathematics.

Progress in the foundations of mathematics has made it possible to formulate all thinkable mathematical concepts, algorithms and proofs in one language and in an impeccable way. This is not in spite of, but partially based on the famous results of Gödel and Turing. In this way statements are about mathematical objects and algorithms, proofs show the correctness of statements and computations, and computations are dealing with objects and proofs. Interactive computer systems for a full integration of defining, computing and proving are based on this. The human defines concepts, constructs algorithms and provides proofs, while the machine checks that the definitions are well formed and the proofs and computations are correct. Results formalized so far demonstrate the feasibility of this 'computer mathematics'. Also there are very good applications. The challenge is to make the systems more mathematician-friendly, by building libraries and tools. The eventual goal is to help humans to learn, develop, communicate, referee and apply mathematics.

Algorithms↗

What is a proof?

To those brought up in a logic-based tradition there seems to be a simple and clear definition of proof. But this is largely a twentieth century invention; many earlier proofs had a different nature. We will look particularly at the faulty proof of Euler's Theorem and Lakatos' rational reconstruction of the history of this proof. We will ask: how is it possible for the errors in a faulty proof to remain undetected for several years-even when counter-examples to it are known? How is it possible to have a proof about concepts that are only partially defined? And can we give a logic-based account of such phenomena? We introduce the concept of schematic proofs and argue that they offer a possible cognitive model for the human construction of proofs in mathematics. In particular, we show how they can account for persistent errors in proofs.

Algorithms↗