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J S Paul

Publications and source records attributed to J S Paul.

At least 19 recordsLinked to original sources
PubMed2001

Coherence-weighted Wiener filtering of somatosensory evoked potentials.

In this paper, we present a Wiener filtering (WF) approach for extraction of somatosensory evoked potentials (SEPs) from the background electroencephalogram (EEG), with sweep-to-sweep variations in its signal power. To account for the EEG power variations, WF is modified by iteratively weighting the power spectrum using the coherence function. Coherence-weighted Wiener filtering (CWWF) is able to extract SEP waveforms, which have a greater level of detail as compared with conventional time-domain averaging (TDA). Using CWWF, the components of the SEP show significantly less variability. As such, CWWF should be useful as an important diagnostic tool able to detect minimal changes in the SEP. In an experimental study of cerebral hypoxia, CWWF is shown to be more responsive to detection of injury than WF or TDA.

Electroencephalography↗
PubMed2000

Initial validation of the functional impairment scale for children and adolescents.

OBJECTIVE: Two studies assessed the validity of the Functional Impairment Scale for Children and Adolescents (FISCA), a multidimensional parent-report questionnaire. METHOD: In study 1, quasi-exploratory and confirmatory procedures tested whether FISCA data for 804 inpatients (mean age = 13.4, 456 boys), collected October 1994 through December 1995, fit a 3-factor model. Study 2 (n = 330) used survival and discriminant analyses to predict recidivism status at 3 and 6 months follow-up from FISCA scores at intake. RESULTS: The 8 FISCA scales reduced to 3 factors describing undercontrolled aggression, social role violations, and self-focused aspects of child functional impairment. Serious impairment on the Aggression and School scales each predicted a 3-fold increase in recidivism risk. Together, impairment scores for Aggression, School, Thinking, and Delinquency correctly identified 73% of the recidivists. However, 51% of the nonrecidivists also were classified as recidivists. CONCLUSIONS: Although these data initially support the FISCA's validity, they underscore the need for more effective strategies to identify severely impaired children whose problems will be sporadic or short-lived.

Adolescent↗
PubMed2000

A transform domain SVD filter for suppression of muscle noise artefacts in exercise ECG's.

The proposed filter assumes the noisy electrocardiography (ECG) to be modeled as a signal of deterministic nature, corrupted by additive muscle noise artefact. The muscle noise component is treated to be stationary with known second-order characteristics. Since noise-free ECG is shown to possess a narrow-band structure in discrete cosine transform (DCT) domain and the second-order statistical properties of the additive noise component is preserved due to the orthogonality property of DCT, noise abatement is easily accomplished via subspace decomposition in the transform domain. The subspace decomposition is performed using singular value decomposition (SVD). The order of the transform domain SVD filter required to achieve the desired degree of noise abatement is compared to that of a suboptimal Wiener filter using DCT. Since the Wiener filter assumes both the signal and noise structures to be statistical, with a priori known second-order characteristics, it yields a biased estimate of the ECG beat as compared to the SVD filter for a given value of mean-square error (mse). The filter order required for performing the subspace smoothing is shown to exceed a certain minimal value for which the mse profile of the SVD filter follows the minimum-mean-quare error (mmse) performance warranted by the suboptimal Wiener filter. The effective filter order required for reproducing clinically significant features in the noisy ECG is then set by an upper bound derived by means of a finite precision linear perturbation model. A significant advantage resulting from the application of the proposed SVD filter lies in its ability to perform noise suppression independently on a single lead ECG record with only a limited number of data samples.

Algorithms↗
PubMed1999

Daily behavior ratings among child and adolescent inpatients: the abbreviated Child Behavior Rating Form.

OBJECTIVE: Child and adolescent psychiatric inpatient facilities are in need of standardized behavior rating scales to assess continuous change in patient behaviors. This study used daily staff ratings to examine the factor structure and psychometric properties of an abbreviated version of the Child Behavior Rating Form (CBRF-A). METHOD: Three hundred eighty-seven inpatients, aged 3 to 17 years, were rated daily by unit staff. Subsamples of patients and/or their parents completed additional measures of behavior problems (Child Behavior Checklist, Functional Impairment Scale for Children and Adolescents) to assess the instrument's validity. RESULTS: Confirmatory factor analyses identified 5 behavior problem dimensions (Oppositionalism, Attention Problems, Overactivity, Withdrawal/Depression, and Anxiety), a second-order Externalizing dimension, and 2 positive behavior dimensions (Positive/Adaptive Social and Compliance/Self-Control). The scales were found to be internally consistent and showed expected age differences, and the scale factor structures were relatively stable over 1- and 2-week intervals. The scales correlated meaningfully with parent ratings of child behavior problems and functional impairment and were predictive of total hospital days. CONCLUSIONS: The psychometric properties of the CBRF-A appear adequate for daily inpatient rating; additional research is needed to determine the usefulness of the CBRF-A in assessing treatment and medication effects over the hospital stay.

Adolescent↗
PubMed1998

Data processing of stress ECGs using discrete cosine transform.

The signal processing steps for the analysis of stress ECGs are aimed at improving the signal to noise ratio (SNR) of recordings in addition to eliminating artifacts due to respiration, movement of arms, etc. In this paper, we bring forth two important applications of the discrete cosine transform (DCT) for noise suppression and removal of baseline wander. The noise suppression algorithm has been framed on the basis of a two step procedure involving singular value decomposition (SVD) smoothing operation in transform domain followed by that in time domain. The mean square error (MSE) resulting from the first step is shown to effectively follow the trend obtained by using an ideal Wiener filter using DCT. In the second step, the degree of closeness to the minimum mean square error (MMSE) of the ideal Wiener filter is improved by subjecting the filtered outputs to a second SVD smoothing operation in time domain. Application of this scheme to noisy records has resulted in near perfect reproduction of the original noise free ECG without significant alterations in its morphological features.

Algorithms↗
PubMed1990

Nuclear, biological and chemical warfare. Part I: Medical aspects of nuclear warfare.

Casualties in earlier wars were due much more to diseases than to weapons. Mention has been made in history of the use of biological agents in warfare, to deny the enemy food and water and to cause disease. In the first world war chemical agents were used to cause mass casualties. Nuclear weapons were introduced in the second world war. Several countries are now involved in developing nuclear, biological and chemical weapon systems, for the mass annihilation of human beings, animals and plants, and to destroy the economy of their enemies. Recently, natural calamities and accidents in nuclear, chemical and biological laboratories and industries have caused mass instantaneous deaths in civilian population. The effects of future wars will not be restricted to uniformed persons. It is time that physicians become aware of the destructive potential of these weapons. Awareness, immediate protective measures and first aid will save a large number of persons. This series of articles will outline the medical aspects of nuclear, biological and chemical weapon systems in three parts. Part I will deal with the biological effects of a nuclear explosion. The short and long term effects due to blast, heat and associated radiation are highlighted. In Part II, the role of biological agents which cause commoner or new disease patterns is mentioned. Some of the accidents from biological warfare laboratories are a testimony to its potential deleterious effects. Part III deals with medical aspects of chemical warfare agents, which in view of their mass effects can overwhelm the existing medical resources, both civilian and military.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗
PubMed1980

Advantages of hypothermic potassium cardioplegia and superiority of continuous versus intermittent aortic cross-clamping.

The relative effectivenss of hypothermic potassium (K) cardioplegia in conjunction with either continuous or intermittent aortic cross-clamping was evaluated in 20 mongrel dogs. Isovolumetric left ventricular (LV) contractions and myocardial biopsies were obtained before and after a total of 90 minutes of aortic cross-clamping. The dogs were randomly divided into four groups of five dogs each as follows: Group I, continuous 90 minute cross-clamping and multidose K at 4 degrees C (40 mEq/L); Group II, intermittent cross-clamping consisting of six 15 minute periods of cross-clamping separated by 5 minute reperfusion periods and K cardioplegia at 4 degrees C given at the start of each cross-clamping period; Group III, continuous 90 minute cross-clamping and multidose buffered saline at 4 degrees C; Group IV, intermittent cross-clamping, consisting of six 15 minute periods of cross-clamping separated by 5 minute reperfusion periods and buffered saline at 4 degrees C given at the initiation of each cross-clamp period. Group I dogs had the best myocardial performance, with no difference between control values of peak LV pressure and dP/dtmax and those recordings obtained 60 minutes after release of the aortic cross-clamp. Significant depression of LV function was noted in all other groups. Examination of force-velocity and length-tension relationships confirmed better myocardial performance in Groups I and II (multidose K at 4 degrees C) than in Groups III and IV (buffered saline at 4 degrees C). Groups I and III (continuous cross-clamping) had no de-rease in diastolic LV compliance after cross-clamping, whereas compliance was decreased in both Groups II and IV (intermittent cross-clamping) at higher preloads (p less than 0.05 and p less than 0.025, respectively). The wet weight/dry weight myocardial ratios were lower in Groups I and III (continuous cross-clamping) than in Groups II and IV (intermittent cross-clamping). Although creatine phosphate (CP) concentrations were rapidly restored by reperfusion in all groups, adenosine triphosphate (ATP) and glycogen myocardial stores were better preserved at the end of cross-clamping in Groups I and II (multidose K at 4 degrees C). Although LV diastolic compliance was decreased and myocardial water content was increased in Groups II and IV (intermittent cross-clamping), no differences in the minimal extent of subendocardial hemorrhage, edema, and contraction-band necrosis were observed among any of the groups examined electron microscopically. The present study identifies continuous aortic cross-clamping with multidose K at 4 degrees C as a superior method of myocardial protection.

Animals↗
PubMed1978

Effects of Sulfite on Metabolism in Isolated Mesophyll Cells from Papaver somniferum.

Exposure (30 minutes) of leaf-free mesophyll cells from the C-3 plant, Papaver somniferum, to concentrations of sulfite (SO(2) + HSO(3) (-) + SO(3) (-)) up to 20 millimolar stimulated the rate of CO(2) incorporation as much as 30%. The sulfite rapidly affects the metabolism of newly incorporated CO(2). Ammonia incorporation into glutamine and subsequent transamination reactions were stimulated during the short term exposure periods while glycolate metabolism apparently was inhibited by bisulfite at two points in the pathway. The results further indicate that glycolate is the major precursor of glycine in these cells. Prolonged periods of exposure (24 hours) to sulfite had somewhat different effects on carbon metabolism: the high concentrations (10 to 20 millimolar) severely inhibited all aspects of cellular metabolism while lower concentrations (1 millimolar) appeared to inhibit ammonia incorporation but stimulated synthesis of sucrose and starch.

Journal Article↗
PubMed1977

Maintenance of High Photosynthetic Rates in Mesophyll Cells Isolated from Papaver somniferum.

The establishment and maintenance of high rates of photosynthetic CO(2) incorporation in mesophyll cells of Papaver somniferum (opium poppy) depend on a regime of dark and light periods immediately following isolation, as well as carefully adjusted conditions of isolation. Analysis of the incorporation pattern of (14)CO(2) by the isolated cells indicates an initial "stress-response" period of approximately 20 hours characterized by increased respiratory-type metabolism and diminished photosynthesis. Under the favorable regime, this period is followed by rapid recovery and the reinstatement of a metabolic state strikingly similar to that of intact leaves in which the initial rate of CO(2) incorporation is between 110 and 175 mumoles CO(2) fixed per mg chlorophyll per hour. The photosynthetic viability of these cells can be maintained for up to 80 hours.

Journal Article↗
PubMed1976

Photorespiration in diatoms. IV. Two pathways of glycolate metabolism in synchronized cultures of Cylindrotheca fusiformis.

Cylindrotheca fusiformis is shown to be able to convert glycolate to glycerate via tartronic semialdehyde as well as by the better known route involving transamination to glycine. Enzymes related to photorespiration were compared in light-dark synchronized cultures of C. fusiformis kept in continuous light in a complete synthetic seawater medium or starved for nitrogen or silicon. Glycolate oxidation remained constant throughout the cell cycle and was unaffected by starvation. Transamination of glyoxylate was stimulated by light, inhibited during nitrogen starvation, and dramatically stimulated by reintroduction of nitrate to the medium. Glyoxylate carboligase was also stimulated by light and inhibited during nitrogen-starvation but only partially recovered activity after reintroduction of nitrate.

Carboxy-Lyases↗