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PubMed2006

Landing for success: a biomechanical and perceptual analysis of on-ice jumps in figure skating.

Technical evaluation in the sport of figure skating is characterized by a subjective marking system. Figure skating judges are responsible for quickly and accurately discerning the quality of technical elements as well as assigning a score to the overall aesthetic appearance of a performance. Traditionally, overall placement marks are assigned for the entire performance; however, the landing of a jump is widely acknowledged as one of the most critical elements of a skater's program. Therefore, our aims were to identify the biomechanical variables that contribute to technical success in executing landings and to establish whether landings rated as biomechanically optimal are also awarded high technical merit scores by judges. Ten nationally ranked competitive figure skaters were asked to execute on-ice, double and triple revolution jumps and to try to land the jumps void of technical faults within a calibrated space. Data were collected at 60 Hz using standard three-dimensional videography. Data reduction was done using the APAS system (Ariel Dynamics Inc). Concurrently, videotapes were viewed and evaluated by 42 accredited judges to determine the perceived technical quality of the landing performances. Judges were asked to evaluate the landing phase of each jump against a landing criteria document. A comparative criteria model was developed to facilitate an assessment of excellence in landing performances through both empirical and subjective analyses. Results of these analyses were twofold: a biomechanical profile of on-ice landings was obtained, and on-ice jump landing strategies rated by empirical evaluations were in agreement with judge's perceptions of the same performances.

Arm↗
PubMed2005

Forward-backward equations for nonlinear propagation in axially invariant optical systems.

We present a general framework to deal with forward and backward components of the electromagnetic field in axially invariant nonlinear optical systems, which include those having any type of linear or nonlinear transverse inhomogeneities. With a minimum amount of approximations, we obtain a system of two first-order equations for forward and backward components, explicitly showing the nonlinear couplings among them. The modal approach used allows for an effective reduction of the dimensionality of the original problem from 3 + 1 (three spatial dimensions plus one time dimension) to 1 + 1 (one spatial dimension plus one frequency dimension). The new equations can be written in a spinor Dirac-like form, out of which conserved quantities can be calculated in an elegant manner. Finally, these equations inherently incorporate spatiotemporal couplings, so that they can be easily particularized to deal with purely temporal or purely spatial effects. Nonlinear forward pulse propagation and nonparaxial evolution of spatial structures are analyzed as examples.

Journal Article↗
PubMedDate not supplied

MAROS: a decision support system for optimizing monitoring plans.

The Monitoring and Remediation Optimization System (MAROS), a decision-support software, was developed to assist in formulating cost-effective ground water long-term monitoring plans. MAROS optimizes an existing ground water monitoring program using both temporal and spatial data analyses to determine the general monitoring system category and the locations and frequency of sampling for future compliance monitoring at the site. The objective of the MAROS optimization is to minimize monitoring locations in the sampling network and reduce sampling frequency without significant loss of information, ensuring adequate future characterization of the contaminant plume. The interpretive trend analysis approach recommends the general monitoring system category for a site based on plume stability and site-specific hydrogeologic information. Plume stability is characterized using primary lines of evidence (i.e., Mann-Kendall analysis and linear regression analysis) based on concentration trends, and secondary lines of evidence based on modeling results and empirical data. The sampling optimization approach, consisting of a two-dimensional spatial sampling reduction method (Delaunay method) and a temporal sampling analysis method (Modified CES method), provides detailed sampling location and frequency results. The Delaunay method is designed to identify and eliminate redundant sampling locations without causing significant information loss in characterizing the plume. The Modified CES method determines the optimal sampling frequency for a sampling location based on the direction, magnitude, and uncertainty in its concentration trend. MAROS addresses a variety of ground water contaminants (fuels, solvents, and metals), allows import of various data formats, and is designed for continual modification of long-term monitoring plans as the plume or site conditions change over time.

Cost-Benefit Analysis↗
PubMed1993

Sympathetic stimulation alters left ventricular relaxation and chamber size.

Alterations in left ventricular (LV) contractility, relaxation, and chamber dimensions induced by efferent sympathetic nerve stimulation were investigated in nine anesthetized open-chest dogs in sinus rhythm. Supramaximal stimulation of acutely decentralized left stellate ganglia augmented heart rate, LV systolic pressure, and rate of LV pressure rise (maximum +dP/dt, 1,809 +/- 191 to 6,304 +/- 725 mmHg/s) and fall (maximum -dP/dt, -2,392 +/- 230 to -4,458 +/- 482 mmHg/s). It also reduced the time constant of isovolumic relaxation, tau (36.5 +/- 4.8 to 14.9 +/- 1.1 ms). Simultaneous two-dimensional echocardiography recorded reductions in end-diastolic and end-systolic LV cross-sectional chamber areas (23 and 31%, respectively), an increase in area ejection fraction (32%), and increases in end-diastolic and end-systolic wall thicknesses (14 and 13%, respectively). End-systolic and end-diastolic wall stresses were unchanged by stellate ganglion stimulation (98 +/- 12 to 95 +/- 9 dyn x 10(3)/cm2; 6.4 +/- 2.4 to 2.4 +/- 0.3 dyn x 10(3)/cm2, respectively). Atrial pacing to similar heart rates did not alter monitored indexes of contractility. Dobutamine and isoproterenol induced changes similar to those resulting from sympathetic neuronal stimulation. These data indicate that when the efferent sympathetic nervous system increases left ventricular contractility and relaxation, concomitant reductions in systolic and diastolic dimensions of that chamber occur that are associated with increasing wall thickness such that LV wall stress changes are minimized.

Animals↗
PubMed1987

Crystallographic data for Streptomyces avidinii streptavidin.

Crystallization conditions are reported for Streptomyces avidinii streptavidin with and without bound biotin. X-ray examination of the free and bound crystal forms shows the streptavidin-biotin complex crystals to be most suitable for high resolution structure analysis. A complete x-ray data set to 2.6 A resolution was collected for the streptavidin-biotin crystals using a two-dimensional area detector. Reduction and analysis of the x-ray diffraction pattern show that the complex crystallizes in the tetragonal space group I4(1)22 (a = b = 98.4 A, c = 125.8 A), with half of the streptavidin tetramer in the crystallographic asymmetric unit.

Bacterial Proteins↗
PubMedDate not supplied

Value of criterion and predictor variables for the study of coronary risk factors.

By means of the factor analysis and the discriminant analysis we studied the structure of the interrelations between the risk factor variables in cardiovascular diseases. The reduction of the dimensionality of data by extracting a small number of common factors has allowed us the identification of the three main factors whose structural change reflects the successive passage through the states of health, risk and illness. To estimate the effectiveness of the prevention action we calculated the D2 distance between the groups of subjects at the two extreme moments. In the last part of the study we determined the predictive value of the risk factor variables considering in turn the main risk factors as criterion variables in terms of the other risk factors taken as predictors.

Age Factors↗
PubMed1981

Image analysis of atypical bronchial squamous epithelial cells. A quantitative and qualitative examination of squamous cell carcinogenesis.

Atypical bronchial squamous epithelial cells from cigarette smokers were digitized using a high-resolution microphotometric scanning system operating at a wavelength of 530 nm. All cells used for the purpose of developing a training set as well as those used as a test set were classified by a team of three cytopathologists. Reduction in the dimensionality of the feature space and cell classification were performed using a new system known as the atypia status index (ASI); this dual-purpose system will specifically classify cells into five distinct classes of progressive atypia as well as quantitate the degree of atypicality of each individual cell. The distribution of cellular ASI values was arranged from lowest to highest and plotted for each subject as a profile. The ASI range has well-defined intervals, representing the five different atypia classes used in the study (squamous metaplasia, mild atypia, moderate atypia, severe atypia and carcinoma). Subjects at different stages of carcinogenesis were found to have significantly different profiles (P less than 0.01). Changes in visual morphologic characteristics and their relation to changes in ASI values for the five different classes of atypia are presented.

Bronchi↗
PubMed1997

Spectrally weighted twisted projection imaging: reducing T2 signal attenuation effects in fast three-dimensional sodium imaging.

A scheme for the reduction of T2 signal attenuation effects in three-dimensional twisted projection imaging is presented. By purposely reducing the sample density at the high spatial frequencies, a considerable reduction in readout time is achieved. The reduction in readout time leads to decreased T2 signal attenuation which translates into improved signal-to-noise ratio (SNR). The SNR improvement is achieved without decreasing the image's resolution since the point spread function depends on the sample weighting as well as the T2 attenuation. The results indicate that SNR improvements of up to 40% can be achieved using the proposed scheme.

Brain↗
PubMed2006

Influence of copper loading and surface coverage on the reactivity of granular iron toward 1,1,1-trichloroethane.

Although iron-based bimetallic reductants offer promise in treating organohalides, the influence of additive mass loading and two-dimensional surface coverage on reductant reactivity has not been fully elucidated. In this study we examine 1,1,1-trichloroethane reduction by Cu/Fe bimetals as a function of Cu loading and surface coverage. Information from a suite of complementary techniques (X-ray photoelectron spectroscopy, Auger electron spectroscopy, and cross-sectional energy-dispersive X-ray spectroscopy) indicates that displacement plating produces a heterogeneous metallic copper overlayer on iron. The dependence of pseudo-first-order rate constants (k(obs) values) for 1,1,1-trichloroethane reduction on Cu loading exhibits two distinct regimes. At Cu loadings less than 1 monolayer equivalent (approximately 10 micromol Cu/g Fe), a pronounced increase in k(obs) is associated with a corresponding increase in the two-dimensional surface coverage of Cu. A weaker dependence of k(obs) on Cu mass is exhibited at loadings in excess of 1 monolayer equivalent, which we ascribe to an increase in the volume of the metallic overlayer. The observed relationship between k(oba) and loading suggests that 1,1,1-trichloroethane reduction occurs on the Cu surface rather than at the interface between the Cu overlayer and the iron substrate.

Copper↗
PubMed2001

Feature selection for DNA methylation based cancer classification.

Molecular portraits, such as mRNA expression or DNA methylation patterns, have been shown to be strongly correlated with phenotypical parameters. These molecular patterns can be revealed routinely on a genomic scale. However, class prediction based on these patterns is an under-determined problem, due to the extreme high dimensionality of the data compared to the usually small number of available samples. This makes a reduction of the data dimensionality necessary. Here we demonstrate how phenotypic classes can be predicted by combining feature selection and discriminant analysis. By comparing several feature selection methods we show that the right dimension reduction strategy is of crucial importance for the classification performance. The techniques are demonstrated by methylation pattern based discrimination between acute lymphoblastic leukemia and acute myeloid leukemia.

Computational Biology↗
PubMed2003

Evaluation of bone reduction in osteo-odontokeratoprosthesis (OOKP) by three-dimensional computed tomography.

PURPOSE: To study the stability and preservation of the osteodental lamina in osteo-odontokeratoprosthesis (OOKP) according to Strampelli with spiral computed tomography (CT). METHODS: Computed tomography of the orbit was performed in nine patients after successful OOKP surgery. Indications for surgery included ocular pemphigoid (three patients), Lyell's syndrome (two patients), graft versus host disease (one patient), and severe chemical burns (three patients). In four eyes, the osteodental lamina was covered with a buccal mucosa graft; in five eyes, a "transpalpebral" approach with the placement of the optical cylinder through the patient's own lid skin was used. The mean time from surgery to examination was 4 years. The age of the patients ranged from 32 to 75 years (mean, 52). Spiral CT in the transaxial plane was performed, followed by three-dimensional (3D) surface reconstruction of the OOKP. The dimensions of the osteodental lamina were measured and compared with measurements taken at the time of surgery. RESULTS: A minor reduction of the lamina, mainly in the anterior and inferior part, could be found in all the patients without loss of stability and integrity of the lamina cylinder complex in seven patients. One patient showed complete resorption of the inferior half of the osteodental lamina, and another patient demonstrated "moth-eaten" dissolution of dentine and bone tissue. No correlation between the degree of reduction in the dimensions and patient age, diagnosis, or length of follow-up could be found. CONCLUSION: Osteo-odontokeratoprosthesis shows good results in patients with corneal blindness not amenable to keratoplasty. Nevertheless, the surgeon must be aware of eventual signs of dissolution of the osteodental lamina, making close follow-up mandatory. Because ultrasound biomicroscopy cannot be used in these cases, spiral CT with 3D reconstruction seems to be a good diagnostic alternative.

Adult↗
PubMed2005

Moire fringe reduction by optical filters in integral three-dimensional imaging on a color flat-panel display.

We propose a method to reduce the color moire fringes that are attributable to the structure of a color flat-panel display in integral three-dimensional imaging. The method uses two types of optical low-pass filter, diffuser and defocus. The effectiveness of the method was confirmed in an experiment. We describe a way to design these filters with moire's residual energy and video signal energy as indices and demonstrate the validity of the model, which combines two filters to reduce moire fringes.

Journal Article↗
PubMed1991

Evaluation of antiarrhythmic drug effects with simultaneous analysis of single ventricular premature contractions, couplets and salvos.

To improve the clinical value of ambulatory Holter electrocardiographic (ECG) monitoring as a tool of antiarrhythmic therapy control, a new statistical model was developed. In a patient group at increased risk of sudden cardiac death, the spontaneous variability of ventricular arrhythmias was assessed, with simultaneous consideration of single ventricular premature complexes, couplets and salvos. The study included 100 patients who suffered from coronary heart disease or idiopathic dilated cardiomyopathy and for whom greater than 30 ventricular premature complexes/h and couplets had been demonstrated on the last Holter ECG before the study. Between 3 and 12 Holter recordings were made for each patient in a drug-free state; the mean follow-up period was 260 days (maximum 1,403). The mean hourly values of the ectopic events (EE) were assessed separately for ventricular premature complexes, couplets and salvos. The spontaneous variability (SV) was calculated for single ventricular premature complexes, couplets and salvos as SV = log (EEday 2 + 0.01/EEday 1 + 0.01) and linked in one, two and three dimensions. Compared with the consideration of only one type of arrhythmia (one-dimensional model), the simultaneous use of two or three types of arrhythmia (two- or three-dimensional model) resulted in considerably lower reduction and aggravation rates as sufficient proof of drug effects. With control intervals up to 1 week, the one-dimensional model yielded reduction rates for ventricular premature complexes, couplets and salvos of -63%, -90% and -95%, respectively. In contrast, with the three-dimensional model, the rates were -28%, -72% and -88%. The corresponding aggravation values were +370, +1,114% and +2,189% versus +38%, +256% and +747%.(ABSTRACT TRUNCATED AT 250 WORDS)

Anti-Arrhythmia Agents↗
PubMed1992

[Doppler echocardiographic evaluation of vasodilator treatments in patients with cardiac insufficiency. Contribution to the combination of isosorbide dinitrate and captopril].

Hemodynamic evaluation of a vasodilator drug is a difficult exercise in which Doppler echocardiography can be a useful tool. We studied the hemodynamic effect of isosorbide dinitrate (ISDN) by Doppler echocardiography in 7 patients with severe cardiac failure despite prolonged therapy with usually effective doses of captopril. The patients were evaluated before (H0) and 24 hours after treatment by ISDN (120 mg/24 hr) (H24) and 10 minutes after sublingual 0.75 mg of trinitrin (H24 + T). M mode echocardiography did not show any significant changes in chamber dimension as reported after vasodilator therapy in patients without cardiac dilation: in patients with severe left ventricular dilatation a reduction in LV filling pressures causes little if any changes in fractional shortening and ventricular dimensions. Two-dimensional echocardiography showed a reduction in end systolic volume and an increase in ejection fraction, emphasizing the superiority of this technique in cases of abnormal left ventricular function and the sensitivity of indices of systolic function to changes in afterload in these patients. Cardiac output measured by Doppler increased during the study. The maximal acceleration did not change significantly and pulmonary artery pressures were stable after administration of nitrates. ISDN caused a marked change in diastolic mitral flow patterns for which there are several explanations: an effect of ISDN on relaxation or LV compliance or on the conditions of LV filling or on both factors together. The presence of mitral regurgitation and/or atrial arrhythmia prevents the use of Doppler indices for analysis of diastolic LV function.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1991

Histogram reduction method for calculating complication probabilities for three-dimensional treatment planning evaluations.

New tools are needed to help in evaluating 3-D treatment plans because of the large volume of data. One technique which may prove useful is the application of complication probability calculations. A method of calculating complication probabilities for inhomogeneously irradiated normal tissues is presented in this paper. The method uses clinical estimates of tolerance doses for a few discreet conditions of uniform partial organ irradiation, an empirical fit of a continuous function to these data, and a technique (the effective volume method) for transforming nonuniform dose-volume histograms into equivalent uniform histograms. The behavior of the effective volume histogram reduction method for various boundary conditions is reviewed. The use of complication probabilities in evaluating treatment plans is presented, using examples from an NCI 3-D treatment planning contract.

Humans↗
PubMed1992

Noncolorimetric measurement of cell activity in three-dimensional histoculture using the tetrazolium dye 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide: the pixel image analysis of formazan crystals.

We describe a novel system for measuring the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction in three-dimensional histoculture which is no longer dependent on colorimetric determination of extracted formazan, but rather is based on a pixel image analysis of formazan crystals, and which allows intratumor heterogeneity to be taken into account. The MTT test is based on the enzymatic reduction of the tetrazolium salt 3-(4,5-dimethylthiazol-2-yl)-2,5-dipheniltetrazolium bromide to formazan crystals by living, metabolically active cells, but not in dead cells. The reaction was carried out in situ in six-well plates on gel-supported histocultured human tumors. After a 24-h incubation with different drugs the tumors were incubated with a solution of MTT. Frozen sections of the tumor pieces were made and the slides were then stained with a propidium iodide solution, whose fluorescence is proportional to the number of cells present. We demonstrate here that the formazan crystals, formed by MTT reduction, reflect polarized light and that this can be quantified by using an image analysis system based on bright-pixel quantitation directly on a frozen section of the original tissue. Combined with the use of the fluorescent dye propidium iodide, also measured by pixel analysis, we can express a ratio between the total amount of MTT reduction and the total number of cells present in the specimen that expresses the effect of drugs on the histocultured tumors. Since histology is well maintained in histoculture it is possible to take into account the heterogeneity present in the tumor with regard to drug response.(ABSTRACT TRUNCATED AT 250 WORDS)

Antineoplastic Agents↗
PubMed2000

One-dimensional dynamics for traveling fronts in coupled map lattices

Multistable coupled map lattices typically support traveling fronts, separating two adjacent stable phases. We show how the existence of an invariant function describing the front profile allows a reduction of the infinitely dimensional dynamics to a one-dimensional circle homeomorphism, whose rotation number gives the propagation velocity. The mode locking of the velocity with respect to the system parameters then typically follows. We study the behavior of fronts near the boundary of parametric stability, and we explain how the mode locking tends to disappear as we approach the continuum limit of an infinite density of sites.

Journal Article↗
PubMed1998

Personality disorder comorbidity with major depression and response to treatment with sertraline or citalopram.

The purpose of this study was to investigate the frequency of DSM-III-R personality disorders in depressed patients treated in primary care, and to examine the effect of sertraline or citalopram on the diagnosis of personality disorders. A total of 308 patients with a major depressive disorder were assessed with the Swedish version of the Structured Clinical Interview for Personality Disorders (SCID) screen questionnaire, before and after 24 weeks double-blind treatment with sertraline (50-150 mg/day) or citalopram (20-60 mg/day). Following treatment, significant reductions in the frequency of paranoid, borderline, avoidant and dependent personality disorder diagnoses were seen in both treatment groups. When the personality disorders were analysed as continuous, dimensional personality traits significant reductions were seen for most personality categories. To elucidate if the observed reductions in personality disorder criteria could be explained by the improvement in depressive symptomatology, a series of multiple regressions were made. Reduction of depression scores was of some importance for the changes in most personality disorders. However, the multiple R never exceeded 0.24 (cluster C). Type of drug was of importance only as concerns obsessive-compulsive personality disorder. Overall, the results suggest that sertraline and citalopram may be beneficial in the treatment of certain personality disorder traits in patients with major depressive disorders.

Adult↗