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PubMed1981

A computer program for determining Vmax from the uncalibrated left ventricular pressure signal and its first derivative.

A computer program was developed to simplify the conventional method for determining the maximal contractile element shortening velocity at zero load (Vmax) by analysis of pressure-velocity graphs during the isovolumic contraction period. From an uncalibrated left ventricular (LV) pressure signal and its first derivative (dP/dt), the graph relating developed LV pressure (Pd) to the corresponding instantaneous value of (dP/dt)/28 Pd was constructed by the computer. The segment of the graph that encompassed approximately the second half of the isovolumic contraction period, as determined by analysis of the dP/dt waveform, was then extrapolated to provide V'max on the ordinate. This V'max was compared with the conventional Vmax obtained from calibrated LV and aortic pressure signals. In 5 dogs both in the control state and during inotropic (epinephrine, propranolol) and noninotropic interventions (phenylephrine or dextran infusion), a high degree of correlation was found relating V'max and Vmax both derived by either linear (Vmax = 0.91 V'max + 0.14; r = 0.933; P less than 0.001) or exponential (Vmax = 0.99 V'max - 0.06; r = 0.959; P less than 0.001) extrapolation of the pressure-velocity graph to zero load. By use of this program, Vmax can be easily and reliably estimated from the uncalibrated LV pressure signal and its first derivative.

Animals↗
PubMed1989

Effect of uncertainty and diagnosticity on classification of multidimensional data with integral and separable displays of system status.

Integrative, objectlike displays have been advocated for presenting multidimensional system data. In this research two experiments assess the effect of uncertainty on the processing of integral and separable displays. In each experiment 30 subjects were trained to classify instances of system state into one of four state categories using a configural display, a bar graph display, or a digital display. In Experiment 1 the range of instances from the state categories was uniform; in Experiment 2 the distribution was biased toward those instances of highly uncertain state category membership. After training, subjects received extended practice classifying system data. In both experiments uncertainty was found to have the greatest effect on classification performance. In Experiment 1 the bar graph display was consistently superior; the configural display was superior to the digital display only under conditions of low uncertainty. In Experiment 2 the superiority of the bar graph display diminished, producing results equivalent to those of the digital display, with the configural display producing the worst performance. The effect of uncertainty on classification performance is discussed, with specific attention paid to the apparent configural and separable properties of the bar graph display.

Adolescent↗
PubMed1992

Choosing specifiers: an evaluation of the basic tasks model of graphical perception.

Effect sizes obtained from 39 experiments were used to evaluate the predictions of the basic tasks model of graphical efficacy. This model predicts that performance will be attenuated with graphical displays as a function of the particular specifier, or visual dimension, used to code data values. In this review the basic tasks model predicted performance more accurately than did Tufte's data-ink principle. In addition, variability in effect sizes across studies revealed that the model was more successful at predicting performance in local (focusing) tasks than in global information synthesis tasks. Furthermore, the model was better at predicting performance in tasks requiring the use of physically present rather than remembered graphs. Further differences in effect sizes resulted from variability in the exact specifiers used in experimental graphs. Minimal differences were obtained among graphs that used position, length, or angle as specifiers. However, graphs that used area or volume to represent quantitative values were associated with consistently worse performance than found with other formats.

Attention↗
PubMed2006

The effects of celeration lines on visual data analysis.

Previous visual analysis research reported that the overall agreement between visual analysis and statistical analysis was poor. In response, some researchers suggested the use of celeration lines to improve the accuracy and reliability of visual analysis. However, subsequent research reported little or no improvement in accuracy with such lines. The present study presented 5 board-certified behavior analysts with a series of behavioral graphs. The participants were asked to answer questions similar to those posed in previous studies but were also asked to talk aloud as they viewed each graph. Results indicate that the participants made accurate decisions for only 72% of the graphs and that celeration lines did not improve overall accuracy. The verbal protocol analysis suggests that participants were as likely to attend to trend when celeration lines were absent as they were when they were present, with the most differences attributable to varying participant competencies and not graph (i.e., celeration line) characteristics.

Behavior Therapy↗
PubMed2006

Maximum common subgraph: some upper bound and lower bound results.

BACKGROUND: Structure matching plays an important part in understanding the functional role of biological structures. Bioinformatics assists in this effort by reformulating this process into a problem of finding a maximum common subgraph between graphical representations of these structures. Among the many different variants of the maximum common subgraph problem, the maximum common induced subgraph of two graphs is of special interest. RESULTS: Based on current research in the area of parameterized computation, we derive a new lower bound for the exact algorithms of the maximum common induced subgraph of two graphs which is the best currently known. Then we investigate the upper bound and design techniques for approaching this problem, specifically, reducing it to one of finding a maximum clique in the product graph of the two given graphs. Considering the upper bound result, the derived lower bound result is asymptotically tight. CONCLUSION: Parameterized computation is a viable approach with great potential for investigating many applications within bioinformatics, such as the maximum common subgraph problem studied in this paper. With an improved hardness result and the proposed approaches in this paper, future research can be focused on further exploration of efficient approaches for different variants of this problem within the constraints imposed by real applications.

Algorithms↗
PubMed2003

A new growth chart for preterm babies: Babson and Benda's chart updated with recent data and a new format.

BACKGROUND: The Babson and Benda 1976 "fetal-infant growth graph" for preterm infants is commonly used in neonatal intensive care. Its limits include the small sample size which provides low confidence in the extremes of the data, the 26 weeks start and the 500 gram graph increments. The purpose of this study was to develop an updated growth chart beginning at 22 weeks based on a meta-analysis of published reference studies. METHODS: The literature was searched from 1980 to 2002 for more recent data to complete the pre and post term sections of the chart. Data were selected from population studies with large sample sizes. Comparisons were made between the new chart and the Babson and Benda graph. To validate the growth chart the growth results from the National Institute of Child Health and Human Development Neonatal Research Network (NICHD) were superimposed on the new chart. RESULTS: The new data produced curves that generally followed patterns similar to the old growth graph. Mean differences between the curves of the two charts reached statistical significance after term. Babson's 10th percentiles fell between the new data percentiles: the 5th to 17th for weight, the 5th and 15th for head circumference, and the 6th and 16th for length. The growth patterns of the NICHD infants deviated away from the curves of the chart in the first weeks after birth. When the infants reached an average weight of 2 kilograms, those with a birthweight in the range of 700 to 1000 grams had achieved greater than the 10th percentile on average for head growth, but remained below the 3rd percentile for weight and length. CONCLUSION: The updated growth chart allows a comparison of an infant's growth first with the fetus as early as 22 weeks and then with the term infant to 10 weeks. Comparison of the size of the NICHD infants at a weight of 2 kilograms provides evidence that on average preterm infants are growth retarded with respect to weight and length while their head size has caught up to birth percentiles. As with all meta-analyses, the validity of this growth chart is limited by the heterogeneity of the data sources. Further validation is needed to illustrate the growth patterns of preterm infants to older ages.

Anthropometry↗
PubMed2005

Communicating quality of life information to cancer patients: a study of six presentation formats.

PURPOSE: To determine which formats for presenting health-related quality of life (HRQL) data are interpreted most accurately and are most preferred by cancer patients. Patients often want a great deal of information about cancer treatments, including information relevant to HRQL. Clinical trials provide methodologically sound HRQL data that may be useful to patients. PATIENTS AND METHODS: In a multicenter study, 198 patients with previously treated cancer participated in a structured interview. Participants judged HRQL information presented in one textual and five graphical formats. Outcome measures included the accuracy of patients' interpretations and ease-of-use and helpfulness ratings for each format. RESULTS: Correct interpretations ranged from 85% to 98% across formats (F = 10.3, P < .0001) with line graphs of mean HRQL scores over time being interpreted correctly most often. Older patients and less-educated patients were less likely to interpret graphs accurately (F = 7.3, P = .008; and F = 10.6, P = .001, respectively), but all groups were most accurate on simple line graphs. Multivariate analysis revealed that format type, participant age and education were independent predictors of accuracy rates. Patients' ratings also varied across formats both for ease of understanding scores (F = 12.1, P < .0001) and for helpfulness scores (F = 13.2, P < .0001), with line graphs being rated highest on both outcomes. CONCLUSION: Patients generally prefer a simple linear representation of group mean HRQL scores, and can accurately interpret data presented in this format more than 98% of the time irrespective of their age group and educational level. The findings have important implications for the communication of clinical trial HRQL results.

Aged↗
PubMed1976

3-dimensional graphic display of electrocardiograms.

We developed a new method to display a potential distribution of the heart activity on the body surface. Electrocardiograms were recorded from many points distributed regularly on the precordial region. From these electrocardiograms three-dimensional graph of potential distribution was produced by a small digital computer and displayed on the CRT. This graph continuously changes with time according to change of potential distribution like an animation. An interpolation method that we had derived took a short execution time and give a smooth approximated curve. Three-dimentional graphs of electrocardiograms were produced for healthy male subjects. From these graphs a transmission of a wave front of the ventricular activation can be seen as if the wave moves over the picture.

Adult↗
PubMed1995

Visual arithmetic, computational graphics, and the spatial metaphor.

People who interact with graphs to perform arithmetic tasks typically employ quantitative features. However, they may employ the spatial metaphor under two alternative conditions: if they have been trained to apply visual arithmetic methods to traditional line and bar graphs, or if they interact with specially constructed and special-purpose computational graphics. Two experiments explored a visual arithmetic method used to train subjects to determine a mean by locating the spatial midpoint of a set of indicators (bars in a bar graph or points in a line graph). In Experiment 1 visual arithmetic subjects determined the mean of five indicators as quickly as they did the mean of two indicators; control subjects performed slower with five indicators. Both groups took more time to add the values of five indicators than to add two indicators. In Experiment 2, unlike control subjects, visual arithmetic subjects' response times in mean trials were unaffected by changes in the y-axis scale. However, both groups were affected by the y-axis scale on addition trials. Neither group was influenced by changes in the distance between indicators. The discussion addresses the transfer of visual arithmetic training to tasks that differ from the one used during training, uses for visual arithmetic and computational graphics, and the role of parallel processing and task restructuring in visual arithmetic.

Adolescent↗
PubMed2005

Convergence to the island-model coalescent process in populations with restricted migration.

In this article we apply some graph-theoretic results to the study of coalescence in a structured population with migration. The graph is the pattern of migration among subpopulations, or demes, and we use the theory of random walks on graphs to characterize the ease with which ancestral lineages can traverse the habitat in a series of migration events. We identify conditions under which the coalescent process in populations with restricted migration, such that individuals cannot traverse the habitat freely in a single migration event, nonetheless becomes identical to the coalescent process in the island migration model in the limit as the number of demes tends to infinity. Specifically, we first note that a sequence of symmetric graphs with Diaconis-Stroock constant bounded above has an unstructured Kingman-type coalescent in the limit for a sample of size two from two different demes. We then show that circular and toroidal models with long-range but restricted migration have an upper bound on this constant and so have an unstructured-migration coalescent in the limit. We investigate the rate of convergence to this limit using simulations.

Algorithms↗
PubMed2000

Nocturnal pulse oximetry as an abbreviated testing modality for pediatric obstructive sleep apnea.

OBJECTIVE: To determine the utility of pulse oximetry for diagnosis of obstructive sleep apnea (OSA) in children. METHODS: We performed a cross-sectional study of 349 patients referred to a pediatric sleep laboratory for possible OSA. A mixed/obstructive apnea/hypopnea index (MOAHI) greater than or equal to 1 on nocturnal polysomnography (PSG) defined OSA. A sleep laboratory physician read nocturnal oximetry trend and event graphs, blinded to clinical and polysomnographic results. Likelihood ratios were used to determine the change in probability of having OSA before and after oximetry results were known. RESULTS: Of 349 patients, 210 (60%) had OSA as defined polysomnographically. Oximetry trend graphs were classified as positive for OSA in 93 and negative or inconclusive in 256 patients. Of the 93 oximetry results read as positive, PSG confirmed OSA in 90 patients. A positive oximetry trend graph had a likelihood ratio of 19.4, increasing the probability of having OSA from 60% to 97%. The median MOAHI of children with a positive oximetry result was 16.4 (7.5, 30.2). The 3 false-positive oximetry results were all in the subgroup of 92 children who had diagnoses other than adenotonsillar hypertrophy that might have affected breathing during sleep. A negative or inconclusive oximetry result had a likelihood ratio of.58, decreasing the probability of having OSA from 60% to 47%. Interobserver reliability for oximetry readings was very good to excellent (kappa =.80). CONCLUSIONS: In the setting of a child suspected of having OSA, a positive nocturnal oximetry trend graph has at least a 97% positive predictive value. Oximetry could: 1) be the definitive diagnostic test for straightforward OSA attributable to adenotonsillar hypertrophy in children older than 12 months of age, or 2) quickly and inexpensively identify children with a history suggesting sleep-disordered breathing who would require PSG to elucidate the type and severity. A negative oximetry result cannot be used to rule out OSA.

Adenoids↗
PubMedDate not supplied

[Blue-on-yellow perimetry in tobacco and alcohol consumers].

PURPOSE: To evaluate the visual field changes in blue-on-yellow perimetry (B/Y) strategy 10-2 in alcohol and tobacco smoking consumers. METHODS: Forty-two eyes of twenty-one users were studied. Fifteen individuals were used as a control group. All volunteers were males. After normal ophthalmologic examinations, central 10-2 (B/Y) was performed in both eyes. Analysis of the results was performed through the alterations in the depth graph defect and number of altered points. RESULTS: It was found that the majority of the chronic alcohol and tobacco smoking consumers had a greater frequency of alterations in the depth graph defect; 40 eyes (95.3%), (> 10 dB), and 27 eyes (64.3%) showed a number of altered points, (> 10 points), (p < 0.0001). All those who were used as a control group showed alterations in the depth graph defect and number of altered points, but had less than 10dB and 10 altered points, respectively. CONCLUSION: A higher number of abnormal points and depth graph defects and number of altered points were observed in alcohol and tobacco smoking consumers reflecting a higher number of alterations in the cells of the parvocellular system, responsible for color function, by B/Y perimetry.

Adult↗
PubMed2005

A functional analytic approach to computer-interactive mathematics.

Following a pretest, 11 participants who were naive with regard to various algebraic and trigonometric transformations received an introductory lecture regarding the fundamentals of the rectangular coordinate system. Following the lecture, they took part in a computer-interactive matching-to-sample procedure in which they received training on particular formula-to-formula and formula-to-graph relations as these formulas pertain to reflections and vertical and horizontal shifts. In training A-B, standard formulas served as samples and factored formulas served as comparisons. In training B-C, factored formulas served as samples and graphs served as comparisons. Subsequently, the program assessed for mutually entailed B-A and C-B relations as well as combinatorially entailed C-A and A-C relations. After all participants demonstrated mutual entailment and combinatorial entailment, we employed a test of novel relations to assess 40 different and complex variations of the original training formulas and their respective graphs. Six of 10 participants who completed training demonstrated perfect or near-perfect performance in identifying novel formula-to-graph relations. Three of the 4 participants who made more than three incorrect responses during the assessment of novel relations showed some commonality among their error patterns. Derived transfer of stimulus control using mathematical relations is discussed.

Adolescent↗
PubMed2004

Diagnosing estimate distortion due to significance testing in literature on detection of deception.

Studies journals typically report or feature results significant by statistical test criterion. This is a bias that prevents obtaining precise estimates of the magnitude of any underlying effect. It is severe with small effect sizes and small numbers of measurements. To illustrate the problem and a diagnosis technique, results of published studies on the detection of deception are graphed. The literature contains large effect sizes affirming that deceptive responses in contrast to truthful responses are associated with more reactive Skin Resistance Responses. These effect sizes when graphed on the x-axis against n on the y-axis are distributed as funnel graphs. A subset of studies show support for predicted small to medium effects on different physiological measures, individual differences, and condition manipulations. These effect sizes graphed by sample ns follow negative correlations, suggesting that effect sizes from published values of t, F, and zeta are exaggerations.

Deception↗
PubMed1995

Software for illustrative presentation of basic clinical characteristics of laboratory tests--GraphROC for Windows.

GraphROC for Windows is a program for clinical test evaluation. It was designed for the handling of large datasets obtained from clinical laboratory databases. In the user interface, graphical and numerical presentations are combined. For simplicity, numerical data is not shown unless requested. Relevant numbers can be "picked up" from the graph by simple mouse operations. Reference distributions can be displayed by using automatically optimized bin widths. Any percentile of the distribution with corresponding confidence limits can be chosen for display. In sensitivity-specificity analysis, both illness- and health-related distributions are shown in the same graph. The following data for any cutoff limit can be shown in a separate click window: clinical sensitivity and specificity with corresponding confidence limits, positive and negative likelihood ratios, positive and negative predictive values and efficiency. Predictive values and clinical efficiency of the cutoff limit can be updated for any prior probability of disease. Receiver Operating Characteristics (ROC) curves can be generated and combined into the same graph for comparison of several different tests. The area under the curve with corresponding confidence interval is calculated for each ROC curve. Numerical results of analyses and graphs can be printed or exported to other Microsoft Windows programs. GraphROC for Windows also employs a new method, developed by us, for the indirect estimation of health-related limits and change limits from mixed distributions of clinical laboratory data.

Clinical Laboratory Techniques↗
PubMed2026

REAPER: a project-centric workflow layer for comparative repeatome analysis.

INTRODUCTION: Repeatome characterization from short-read sequencing data is widely performed using RepeatExplorer2/TAREAN. However, long-lived multisample projects and explicit comparative designs are often executed as ad hoc command sequences that are hard to version, rerun, and monitor on shared compute environments - a gap that motivates a project-centric workflow layer for repeatome analysis. METHODS: We present REAPER (Repeatome Extended Analysis Pipeline-Execution and Reporting), a project-centric workflow layer that couples a modular Snakemake pipeline with a Python project manager to enforce a stable on-disk layout and configuration-driven execution for single-sample and comparative repeatome analyses. REAPER does not implement a new repeat-discovery algorithm; it is an orchestration layer, and biological accuracy for clustering and satellite calling depends on the underlying RepeatExplorer2/TAREAN and satMiner methods it coordinates. REAPER standardizes: Read QC Deterministic subsampling and preparation RepeatExplorer2/TAREAN execution via seqclust, with satMiner-inspired iterative assembly Post-TAREAN BLAST-based annotation against curated repeat collections (optionally including taxon-scoped NCBI-derived resources with freshness checks) Optional graph-based comparative reports The pipeline makes comparative read allocation, prefix policy, and analysis-ready tables explicit; caching supports incremental reruns and structured logs support monitoring. Performance was assessed using a Triticeae short-read dataset (five samples), with rule-level logging of runtime and memory across pipeline stages. RESULTS: Rule-level performance logs show that graph-based clustering dominates runtime and memory, while QC and preparation steps are lightweight by comparison. Graph-report annotations for the Triticeae project additionally link high-ranking clusters to established repeat markers - including pTa794- and pSc119-class entries in curated databases. DISCUSSION: These findings illustrate biologically interpretable outputs (recovery of known Triticeae repeat markers) alongside quantitative performance metrics (identification of graph-based clustering as the dominant computational cost). By making comparative read allocation, prefix policy, and analysis-ready tables explicit - and by supporting caching and structured logging - REAPER supports reproducible comparative repeatome analysis in evolving multisample projects. As an orchestration layer rather than a discovery algorithm, REAPER's contribution lies in reproducibility, monitorability, and comparative-analysis infrastructure, with biological accuracy remaining contingent on the underlying RepeatExplorer2/TAREAN and satMiner methods.

TAREAN↗
PubMed1998

The effect of autocorrelation on the results of visually analyzing data from single-subject designs.

OBJECTIVE: Single-subject research designs are used to conduct clinical research and outcome evaluation in occupational therapy. Confusion exists regarding the best method to analyze and interpret single-subject data. METHOD: One hundred graphs displaying the results of published single-subject research were examined to determine the influence of autocorrelation on the visual inferences made by the original investigators. The graphs were selected from 20 articles published over 10 years in seven rehabilitation journals. The data were extrapolated and lag 1 autocorrelation coefficients computed for both the baseline and treatment phases. RESULTS: Data analysis focused on two issues: (a) whether a relationship existed between the amount of autocorrelation present in a graph and the conclusion on the basis of visual analysis and (b) whether the amount of autocorrelation varied across different phases of the single-subject graphs. When a significant degree of autocorrelation was present, researchers using visual analysis were more likely to conclude that there was no clinically significant change in performance. Autocorrelation values were significantly higher in the treatment phases of the single-subject designs. CONCLUSION: Additional research is needed to establish a set of decision rules to assist clinicians in using visual analysis to evaluate the results of single-subject research.

Data Interpretation, Statistical↗
PubMed1991

Normal ultrasonic fetal growth ratios evaluated in cases of fetal disproportion.

During a 2-year period, 5476 normal routine obstetrical ultrasound investigations were performed in the 2nd trimester (16th to 20th week). Data on biparietal diameter (BPD), abdominal diameter (AD) and femur length (FL) have been obtained from this material. Ratios between BPD/AD and BPD/FL have been calculated, and from these ratios, graphs were constructed. Only nine normal fetuses (0.2%) were found to be outside mean +/- 3 SD, and none of the normal cases were +/- 4 SD, so this is perhaps a better guideline for those warranting further investigation. To evaluate if these ratios could better reflect disproportional fetal growth, three cases of triploidy and four cases of dwarfism were tested against these ratios. Triploidy was obvious on the BPD/AD graph and dwarfism on the BPD/FL graph. The ratios were not found to be conclusive in the intrauterine diagnosis of trisomy 21 or of trisomy 18, as only 4 of 17 cases were obvious on the graphs.

Embryonic and Fetal Development↗