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At least 1,189 records · Page 66Linked to original sources
PubMed1989

BASIC program for non-parametric fitting of user-defined functions to experimental data with plotting of results.

Graphic displays of experimental results facilitate decisions regarding mathematical models which relate experimental results to controlled parameters. Experiments frequently produce response variables which are non-linearly related to the controlled variable. Computer programs can be useful to fit model functions to experimental data. SIMPLOT7, written in Microsoft QuickBASIC, provides graphic display of experimental data and non-parametric fitting of user-defined functions to experimental data. The algorithm utilizes simplex-based non-parametric minimization of residuals, and the user-defined function may contain up to seven parameters to be determined for best fit. Once optimum fit values have been determined, both function and data can be graphed for visual inspection of the result.

Computer Simulation↗
PubMed2005

Separation and preconcentration phenomena in internally heated poly(dimethylsilicone) capillaries: preliminary modelling and demonstration studies.

The concept of achieving low-resolution separations in internally heated capillary membranes is discussed in terms of controlling the diffusion coefficients of volatile organic compounds in poly(dimethylsilicone) membranes in space and time. The behaviour of 1,1,1-trichloroethane in polydimethylsilicone was used in conjunction with a mixed-physics finite element model, incorporating second order partial differential equations, to describe time and spatial variations of mass-flux, membrane temperature and diffusion coefficients. The model, coded with Femlab, predicted highly non-linear diffusion coefficient profiles resulting from temperature programming a 500 [micro sign]m thick membrane, with an increase in the diffusion coefficient of approximately 30% in the last 30% of the membrane thickness. Simulations of sampling hypothetical analytes, with disparate temperature dependent diffusion coefficient relationships, predicted distinct thermal desorption profiles with selectivities that reflected the extent of diffusion through the membrane. The predicted desorption profiles of these analytes also indicated that low resolution separations were possible. An internally heated poly(dimethylsilicone) capillary membrane was constructed from a 10 cm long, 1.5 mm od capillary with 0.5 mm thick walls. Thirteen aqueous standards of volatile organic compounds of environmental significance were studied, and low-resolution separations were indicated, with temperature programming of the membrane enabling desorption profiles to be differentiated. Further, analytically useful relationships in the [micro sign]g cm(-3) concentration range were demonstrated with correlation coefficients >0.96 observed for linear regressions of desorption profile intensities to analyte concentrations.

Journal Article↗
PubMed2005

[Determination of phenylarsenic compounds in environmental samples by high performance liquid chromatography].

A reversed-phase high performance liquid chromatographic method was developed for simultaneous determination of phenylarsonic acid (PAA), phenylarsine oxide (PAO), diphenylarsinic acid (DPAA), bis (diphenylarsine) oxide (BDPAO) and triphenylarsine (TPA) in soil samples. The extraction solvent for soil samples was acetonitrile and ultrasound was used in the extraction. Good separation was achieved by using an Inertsil CN-3 column (250 mm x 4.6 mm i.d., 5 microm) with the following conditions: gradient program of mobile phase, a 10 min linear gradient from 100% A (a mixture of acetonitrile-2.5 g/L KH2PO4 (pH 2.0) buffer (5:95, v/v) ) to 100% B ( a mixture of acetonitrile-2. 5 g/L KH2PO4 (pH 2.0) buffer (50:50, v/v)), and isocratic at 100% B from 10.01 min to 28 min; flow rate of 1.0 mL/min; time-programmed UV detection at 210 nm (0 - 10.5 min, 20 - 28 min) and 268 nm (10. 5 - 20 min). The linear range of PAA, PAO, DPAA, BDPAO and TPA were 8 - 30, 5 - 40, 20 -4000, 120 - 8000 and 1 - 60 mg/L, respectively. The detection limits at a signal-to-noise ratio of 3 were 0.1, 0.1, 0.2, 10, and 0.1 mg/L for PAA, PAO, DPAA, BDPAO and TPA, respectively.

Arsenicals↗
PubMed1983

125I-labeled radioimmunoassay kits for progesterone evaluated for use in an vitro fertilization program.

We have evaluated two commercially available 125I radioimmunoassay kits (Diagnostic Products Corp., DPC; and Radioassay Systems Laboratories, RSL) for measurement of serum or plasma progesterone, to determine their suitability for use in in vitro fertilization programs. Both kits were suitably rapid for program requirements. Results by both were linear with concentration up to 60 nmol/L, and both had acceptable lower detection limits of 0.3 nmol/L. Kit-determined progesterone concentrations (y) for 100 patients' samples correlated well with results by our existing 3H radioimmunoassay method (y = 1.11x + 0.2, r = 0.965 for the DPC kit; y = 1.01x + 1.4, r = 0.974 for the RSL kit). Mean analytical recovery for the RSL kit was 116%, that for the DPC kit, 202%. Within-batch precision, expressed as the mean CV for three concentrations of progesterone, was 6.5% for the RSL kit, and 16.4% for the DPC kit; between-day CV was 8.1% for the RSL kit, 17.7% for the DPC kit. We conclude that the RSL kit provides a rapid, precise, and accurate assay for serum progesterone, suitable for use in a fertilization program, but do not recommend the DPC kit for either this purpose or the more general purpose of tracking menstrual cycles.

Evaluation Studies as Topic↗
PubMed1995

One-year mortality prognosis in heart failure: a neural network approach based on echocardiographic data.

OBJECTIVES: This study sought to assess the usefulness and accuracy of artificial neural networks in the prognosis of 1-year mortality in patients with heart failure. BACKGROUND: Artificial neural networks is a computational technique used to represent and process information by means of networks of interconnected processing elements, similar to neurons. They have found applications in medical decision support systems, particularly in prognosis. METHODS: Clinical and Doppler-derived echocardiographic data from 95 consecutive patients with diffuse impairment of myocardial contractility were studied. After 1 year, data regarding survival or death were obtained and produced the prognostic variable. The data base was divided randomly into a training data set (47 cases, 8 deaths) and a testing data set (48 cases, 7 deaths). Results of artificial neural network classification were compared with those from linear discriminant analysis, clinical judgment and conventional heuristically based programs. RESULTS: The study group included 57 male (47 survivors) and 38 female patients (33 survivors). Linear discriminant analysis was not efficient for separating survivors from nonsurvivors because the accuracy at the ideal cutoff value was only 67.4%, with a sensitivity of 67.5%, positive predictive value of 27.8% and negative predictive value of 91.5%. In contrast, all artificial neural networks were able to predict outcome with an accuracy of 90%, specificity of 93% and sensitivity of 71.4%, for the best artificial neural network. Both clinical judgment and automatic heuristic methods were also inferior in performance. CONCLUSIONS: The artificial neural network method has proved to be reliable for implementing quantitative prognosis of mortality in patients with heart failure. Additional studies with larger numbers of patients are required to better assess the usefulness of artificial neural networks.

Adolescent↗
PubMed1980

A package of computer programs designed to simulate pharmacokinetic monitoring of drug therapy.

Three programs are presented which have been developed to simulate conditions encountered in the pharmacokinetic adjustment of dosage regimens. The programs include a drug with one-compartment kinetics, whose elimination is dependent on renal function (gentamicin), a drug with two-compartment kinetics (theophylline), and a drug whose elimination follows non-linear Michaelis-Menten kinetics (phenytoin). The programs may be used as an aid to instruction in clinical pharmacokinetics and to develop and test new methods of pharmacokinetic adjustment of dosage regimens.

Computers↗
PubMed1996

Reducing alcohol-impaired driving in Massachusetts: the Saving Lives Program.

OBJECTIVES: The purpose of this study ws to assess whether a community program begun in March 1988 that organized multiple city departments and private citizens could reduce alcohol-impaired driving, related driving risks, and traffic deaths and injuries. METHODS: Trends in fatal crashes and injuries per 100 crashes were compared in Saving Lives Program cities and the rest of Massachusetts from March 1984 through February 1993. In annual roadside surveys conducted at randomly selected locations, safety belt use among occupants of 54577 vehicles and travel speeds of 118442 vehicles were observed. Four statewide telephone surveys (n = 15188) monitored self-reported driving after drinking. RESULTS: In program cities relative to the rest of Massachusetts during the 5 program years in comparison with the previous 5 years, fatal crashes declined 25%, from 178 to 120, and fatal crashes involving alcohol decreased 42%, from 69 to 36. Visible injuries per 100 crashes declined 5%, from 21.1 to 16.6. The proportions of vehicles observed speeding and teenagers who drove after drinking were cut in half. CONCLUSIONS: Interventions organized by multiple city departments and private citizens can reduce driving after drinking, related driving risks, and traffic deaths and injuries.

Accidents, Traffic↗
PubMed1988

A computer-based method for on-line acquisition and analysis of bronchial challenge test.

We developed a computer program for the optimization and management of data collection in order to compute the change of forced expiratory volume in the first second (delta FEV1), provocative doses and to plot the dose-response curve for bronchial challenge test. Doses of methacholine are entered via the keyboard and forced vital capacity (FVC) with the highest FEV1 value obtained in each step is selected. When the imposed threshold of response has been reached, doses of administered methacholine and corresponding spirometric parameters are displayed and printed. Dose-response relationships are analysed: the increase of delta FEV1 for each unit of metacholine is computed in the interval between the two doses where delta FEV1 reached one of the imposed values (i.e. 15% or 20% or 30%). Finally spirometric values, dose-response curve and provocative doses are shown in a print-out. Computer values of provocative doses are higher than those obtained manually. This difference may be ascribed to the incorrect manual linear extrapolation. In conclusion the computer program is able to reduce consistently the time spent to analyze data from bronchial challenge test and allows a more precise determination of provocative doses by avoiding also inter-intra individual errors.

Asthma↗
PubMed1982

A BASIC program package for weighted least squares solutions using a microprocessor with disc memory.

The fitting of linear additive models to data by weighted least squares methods has been programmed in BASIC. By splitting up the matrix solution into several steps, the RAM memory space needed in a microprocessor by the corresponding programs was reduced, allowing room for larger matrices. Storage of intermediate products, and of subsequent programs in the sequence , was on a mini floppy dual-disc drive. Using an extended BASIC interpreter permitting several files to be open during a program, the program package compromised between computing time and problem size. Problems involving 1600 element matrices were run on a micro having 32000 bytes of memory, allowing for example, the fitting of a model with 22 parameters to 72 observations.

Computers↗
PubMed1992

A three-year evaluation of the know your body program in inner-city schoolchildren.

The impact of the Know Your Body (KYB) comprehensive school health education program was evaluated in a sample of first through sixth-grade students from New York City, using two analytic strategies: a longitudinal cohort and a "posttest only" cohort. In both cohorts, program impact was examined between condition (i.e., KYB vs. no-treatment comparison group) as well as within condition (i.e., low, moderate, and high student exposure). Students in the longitudinal cohort (n = 1,209) who were exposed to high implementation teachers had significantly (p < .05) lower total plasma cholesterol and systolic blood pressure at 3-year posttest than comparison students. Students in the posttest only cohort (n = 3,066) who had high implementation teachers showed significantly (p < .05) lower total plasma cholesterol, systolic blood pressure, self-reported intake of meat and desserts, as well as higher health knowledge and self-reported intake of "heart healthy" foods and vegetables than comparison students. In both cohorts, program effects for several outcome variables were linearly related to level of student exposure to the curriculum, suggesting a dose-response effect. While several methodologic limitations may have influenced study outcomes, these data nonetheless appear to confirm that the KYB program can have a significant positive impact on the knowledge, behavior, and selected risk factors of students in primary grades and that efforts to disseminate and evaluate school health education programs should include strategies to monitor and enhance teacher implementation.

Blood Pressure↗
PubMedDate not supplied

Pharmacokinetic-pharmacodynamic modelling and simulation using the electrical circuit simulation program SPICE2.

The use of the electrical circuit simulation program SPICE2 for performing digital computer simulations of linear and non-linear pharmacokinetic-pharmacodynamic models is described. SPICE2 utilizes the principles of network thermodynamics (thermodynamics of electrical circuits). These principles dictate analogy between the conservation laws of chemical reactions and mass transport and Kirchhoff's laws of current and voltage balance, and also prove that Fick's law of diffusion is isomorphous with the conductance form of Ohm's law. Detailed descriptions of program inputs, formats, and options for simulation of linear and non-linear pharmacokinetic-pharmacodynamic systems are provided, with appropriate examples. Single as well as multiple dose simulations (accumulation kinetics and dynamics) are discussed. The advantages of SPICE2 over other available simulation packages, including user-friendliness, ease of operation, versatility, power, and the economy of time and effort afforded, are emphasized. The educational value of SPICE2 as a highly versatile tool for teaching both fundamental and complex pharmacokinetic-pharmacodynamic concepts, as well as its routine usage in elucidating complex research problems, are also discussed.

Cimetidine↗
PubMed1997

Sudden infant death and prevalence of whooping cough in the Swedish and Norwegian communities.

UNLABELLED: Whooping cough (WC) has been suggested to be a trigger factor for sudden infant death (SID), the proposed mechanism being unrecognised hypoxaemic episodes. In contrast to Norway, Sweden ceased its immunisation programme against Bordetella pertussis (BP) in 1979. We investigated the relation between SID mortality and the prevalence of BP during 1983 to 1988, by month, in the two ethnically and socially similar, bordering countries adopting different strategies towards WC. In addition, the greater Stockholm area was analysed. For both countries the prevalence of BP was collected from monthly reports by regional health officers. SID mortality rates were provided by the Norwegian Central Bureau of Statistics and the SID registry at the Swedish National Board of Health and Welfare. The relation between SID mortality rate and prevalence of WC, by month, was analysed by linear regression. In addition, the consistency of seasonal fluctuations was investigated by analysing the covariance between average, pooled, monthly values of the two variables. SID mortality rate followed significantly the monthly prevalence of BP in Sweden (P < 0.01) and Stockholm (P < 0.0001) during the study period. In Norway there was a significant correlation only during the epidemic outbreak of WC (P < 0.05), but not for the whole study period. When controlling for seasonality a significant correlation remained in the urban area of Stockholm (P < 0.05). CONCLUSION: It is suggested that covariations between WC and SID mortality rate may be related to transmission rate and immunisation status of the investigated population.

Analysis of Variance↗
PubMed2004

A unified quadratic-programming-based dynamical system approach to joint torque optimization of physically constrained redundant manipulators.

In this paper, for joint torque optimization of redundant manipulators subject to physical constraints, we show that velocity-level and acceleration-level redundancy-resolution schemes both can be formulated as a quadratic programming (QP) problem subject to equality and inequality/bound constraints. To solve this QP problem online, a primal-dual dynamical system solver is further presented based on linear variational inequalities. Compared to previous researches, the presented QP-solver has simple piecewise-linear dynamics, does not entail real-time matrix inversion, and could also provide joint-acceleration information for manipulator torque control in the velocity-level redundancy-resolution schemes. The proposed QP-based dynamical system approach is simulated based on the PUMA560 robot arm with efficiency and effectiveness demonstrated.

Algorithms↗
PubMed2026

Dissecting genetic variance structure and evaluating genomic prediction models for single-cross hybrids derived from Stiff Stalk and Non-Stiff Stalk maize heterotic groups.

The early 20th-century discovery of heterosis and the establishment of heterotic groups transformed maize (Zea mays L.) into a keystone of global agriculture. However, maize breeding faces two significant challenges: the gradual decline of general combining ability (GCA) variance within heterotic groups and the impracticality of testing all possible single crosses in the early stages of a breeding program. Here, we developed genomic best linear unbiased prediction (GBLUP)-based multikernel models, using additive and two alternative nonadditive genomic relationship matrices, to estimate the variance components associated with the general combining ability of Stiff Stalk (SS) and Non-Stiff Stalk (NSS) heterotic groups and the specific combining ability arising from their crosses. We further applied these models to predict the performance of untested single-cross combinations under varying levels of parental information. We showed that the SS and NSS groups retained significant GCA variance across traits in both early- and late-maturity groups. The SS group, in contrast, exhibited no detectable GCA variance in grain yield for the intermediate-flowering subset of hybrids, highlighting a limitation for future genetic improvement. Furthermore, our results showed that GBLUP-based multikernel models effectively identified superior hybrids when parental information was available. In the absence of this information, however, these models underperformed compared to covariance-based approaches. Both nonadditive matrices yielded similar results, indicating that they capture comparable genetic relationship patterns despite their distinct formulations. Overall, this study sheds light on the future use of US maize commercial germplasm and demonstrates how GBLUP-based multikernel models can improve the efficiency of hybrid breeding programs.

Zea mays↗
PubMed2005

The "Generacion Diez" after-school program and Latino parent involvement with schools.

The current study examines associations between participation in after-school programs and change in Latino parent involvement with schools. Hierarchical linear regression analyses demonstrated that parents of children who had higher after-school program attendance rates were significantly more likely to report increases in the quality of relationships with their children's teachers, frequency of parent-teacher contact, and engagement with their children's schooling over a two-year period. However, greater home educator contacts were related to decreases in quality and quantity of parent-school involvement. A primary implication is that attendance in school-based after-school programs may draw parents into children's regular-day school context. Editors' Strategic Implications The authors illustrate the promising practice of using after-school programs to promote parent involvement and to help integrate the often disparate family and school contexts for Latino children.

Child↗
PubMed1995

Goal setting as a strategy for health behavior change.

This article discusses the beneficial effects of setting goals in health behavior change and maintenance interventions. Goal setting theory predicts that, under certain conditions, setting specific difficult goals leads to higher performance when compared with no goals or vague, nonquantitative goals, such as "do your best." In contrast to the graduated, easy goals often set in health behavior change programs, goal setting theory asserts a positive linear relationship between degree of goal difficulty and level of performance. Research on goal setting has typically been conducted in organizational and laboratory settings. Although goal setting procedures are used in many health behavior change programs, they rarely have been the focus of systematic research. Therefore, many research questions still need to be answered regarding goal setting in the context of health behavior change. Finally, initial recommendations for the successful integration of goal setting theory in health behavior change programs are offered.

Goals↗
PubMed1985

Effective extraction of diagnostic ECG waveform information using orthonormal basis functions derived from body surface potential maps.

A common basis of orthogonal waveform functions was derived from 128 lead body surface potential maps of 405 subjects. Twelve such orthogonal functions or frames were adequate for reconstruction of original ECGs from the beginning of QRS to the end of T. A larger number of frames (18) was required when basis functions were derived separately for QRS (10) and ST-T segments (8). Diagnostic information content of the coefficients of the orthogonal basis functions was evaluated in comparison with Minnesota Code criteria for myocardial infarction and with a more advanced multivariate ECG analysis program (Pipberger Program). This was done by deriving a linear discriminant function for separating normals from ECGs of patients with myocardial infarction and testing the discriminant in a different test population of infarcts and normals. The diagnostic accuracy of orthogonal basis functions was as good as that of Pipberger's program and considerably better than that of the Minnesota Code. The classification method described is insensitive to noise and errors in detecting QRS and T wave onsets and offsets or in selecting proper baseline for amplitude measurements. The robustness and enhanced classification stability with respect to noise and minor wave detection errors is a potential advantage particularly in serial ECG comparison.

Adult↗