Predicted Mean Values Research Articles

Diagnostic sonographic changes in the kidneys of 20 infants with congenital nephrotic syndrome of the Finnish type

A renal ultrasonographic study was performed on 20 infants with congenital nephrotic syndrome of the Finnish type. Follow-up ultrasonographic data were obtained on 13 of these patients. The renal lengths increased after 2 months of age. Later, at the age of approximately 18 months, the renal size had decreased again, and was within 2 SD of the predicted mean value. During the first 2 months of life the renal cortex was hyperechogenic and corticomedullary differentiation was clearly visible. Between 2 and 12 months of age the renal cortex was still hyperechogenic in all kidneys, but corticomedullary differentiation had disappeared from 10 of the 26 kidneys examined. After 12 months of age the kidney parenchyma was hyperechogenic and most kidneys had lost corticomedullary differentiation. Thus, the sonographic follow-up is one of the main diagnostic indices f congenital nephrotic syndrome.

Diagnostic sonographic changes in the kidneys of 20 infants with congenital nephrotic syndrome of the Finnish type

A renal ultrasonographic study was performed on 20 infants with congenital nephrotic syndrome of the Finnish type. Follow-up ultrasonographic data were obtained on 13 of these patients. The renal lengths increased after 2 months of age. Later, at the age of approximately 18 months, the renal size had decreased again, and was within 2 SD of the predicted mean value. During the first 2 months of life the renal cortex was hyperechogenic and corticomedullary differentiation was clearly visible. Between 2 and 12 months of age the renal cortex was still hyperechogenic in all kidneys, but corticomedullary differentiation had disappeared from 10 of the 26 kidneys examined. After 12 months of age the kidney parenchyma was hyperechogenic and most kidneys had lost corticomedullary differentiation. Thus, the sonographic follow-up is one of the main diagnostic indices f congenital nephrotic syndrome.

Models to predict Secchi depth in small glacial lakes

This study quantifies and ranks variables of significance to predict mean values of Secchi depth in small glacial lakes. The work is based on a new, extensive set of data from 88 Swedish lakes and ...

Models to predict net and gross sedimentation in lakes

This study models net and gross sedimentation in lakes. The fluxes of material play an important role in most lake contexts. They influence transport, bio-uptake and ecological effects of most toxins and nutrients. The aim is to present a new type of 'mixed' dynamic/statistical model and to discuss advantages and disadvantages with this approach. Empirical data to validate the model emanate from sediment traps from 25 lakes. Rates of gross sedimentation in traps were compared to catchment and morphometric parameters determined from maps in an attempt to identify the processes that influence sedimentation. The most important variables are relative depth (linked to resuspension), forest and open land cover (of the near area of the catchment), relief of catchment, coverage of mires and lakes, and the lake water retention time. This study shows that it is easy to lose predictive power in dynamic models relative to empirical models, in which each parameter constant and x-parameter automatically accounts for the complexities in natural ecosystems. In dynamic models empirical knowledge is replaced by logical constructions, which may not be accurate. The mixed model would need to be extended with new large submodels to predict, for example mean distribution coefficient of total-P in tributaries, tributary suspended load, rate of sedimentation and resuspension rate. This would result in a huge 'prescriptive' model with wide uncertainty limits for the predicted mean values for net and gross sedimentation.

Strength size effect of laminated composites

This paper presents results of theoretical and experimental analysis of the effect of size on the strength of laminated composites. On the basis of the suggested probabilistic analytical model of the composite, which is determined by sequential multi-step failure of single sublaminates, expressions for prediction of the random strength distribution and reliability are presented. The influence of the number of sublaminates (composite thickness) on general regularities of the strength size effect is shown, analyzed in detail, and explained. Experimental analysis of the strength size effect is carried out on examples of carbon-fiber-reinforced composites with lay-ups [0] n at n =10, 20, 40, 60, and [( 0 2 90 ° ) s] n at n = 4 and 10, under uniaxial tension. Good agreement with the predicted mean values of the tensile strength is shown. Standardized tables of the mean statistical characteristics of the laminated composite random strength in a plane stress state (mean value, coefficient of variation) are offered for practical engineering applications.

Models to predict water chemical cluster variables

This study is an attempt to quantify and rank variables of significance to predict mean values of lake pH and related variables (alkalinity, conductivity, hardness, etc.) in small glacial lakes. The work is based on a new and extensive set of data from 95 Swedish lakes and their catchment areas. Several empirical models based on catchment and lake morphometric parameters have been presented. These empirical models can only be used to predict mean values of these variables for lakes of the same type, and these models based on “geological” map parameters can evidently not be used for highly time-dependent and site-typical predictions. Various hypotheses concerning the factors regulating the mean values of the cluster variables were formulated and tested. Different statistical tests were used to separate random influences from causal. The most important “map parameters” were: the percent of rocks and open (=cultivated) land in the so-called near area to the lake [as determined with the drainage area zonation (DAZ) method], mean depth, linked to resuspension and the form and size of lakes, relief of the drainage area and lake area. Each of these variables only provides a limited degree of (statistical) explanation of the variability in mean annual values of pH and the water chemical cluster variables among the lakes. The predictability of some of the models can be markedly improved by accounting for the distribution of the characteristics in the drainage area. The variability in mean annual values of pH (and related variables) from other parameters, such as specific anthropogenic load, etc., may then be quantitatively differentiated from the impact of these “geological” parameters. This paper also gives a simple method to estimate natural, preindustrial reference values of these water chemical variables from the presented models.

Mean thermospheric winds observed from Halley, Antarctica

Abstract. Thermospheric winds on a total of 237 nights have been studied for the effects due to geomagnetic activity, solar flux, and season. The observations have been made from 1988 to 1992 by a Fabry-Perot interferometer (FPI) operating at Halley (75.5°S, 26.6°W), Antarctica. This is the first statistical study of thermospheric winds near the southern auroral zone. The main factor affecting the wind velocities is the geomagnetic activity. Increases in activity cause an increase in the maximum equatorward wind, and cause the zonal wind in the evening to become more westward. Smaller changes in the mean wind occur with variations in season and solar flux. The small variation with solar flux is more akin to the situation found at mid-latitudes than at high latitudes. Since the geomagnetic latitude of Halley is only 61°, it suggests that the variability of the wind with solar flux may depend more on geomagnetic than geographic latitude. These observations are in good agreement with the empirical Horizontal Wind Model (HWM90). However, comparisons with predictions of the Vector Spherical Harmonic Model (VSH) show that for low geomagnetic activity the predicted phases of the two components of the wind closely resemble the observations but the modelled amplitudes are too small by a factor of two. At high geomagnetic activity the major differences are that modelled zonal velocity is too westward in the evening and too eastward after 04 UT. The modelled ion densities at the F-region peak are a factor of up to 9 too large, whilst the predicted mean value and diurnal variation of the altitude of the peak are significantly lower than those observed. It is suggested that these differences result from the ion loss rate being too low, and an inaccurate model of the magnetic field.

Enhancing design-for-test for active analog filters by using CLP(ℜ)

We describe a computer-aided approach to automatic fault isolation in active analog filters which enhances the design-for-test (DFT) methodology proposed by Soma (1990). His primary concern was in increased controllability and observability while the fault isolation procedure was sketched only in general terms. We operationalize and extend the DFT methodology by using CLP(R) to model analog circuits and by a model-based diagnosis approach to implement a diagnostic algorithm. CLP(R) is a logic programming language which combines symbolic and numeric computation. The diagnostic algorithm uses different DFT test modes and results of voltage measurements for different frequencies and computes a set of suspected components. Ranking of suspected components is based on a measure of (normalized) standard deviations from predicted mean values of component parameters. The diagnosis is performed incrementally, in each step reducing the set of potential candidates for the detected fault. Presented case studies show encouraging results in isolation of soft faults of a given low pass biquad filter.

Groups of Ocean Waves: Linear Theory, Approximations to Linear Theory, and Observations

Statistics of wave groups observed for a wide range of wave heights, power-spectral shapes, and water depths are compared to the statistics predicted by both direct numerical simulation and analytic approximation of linear wave theory. Comparisons to numerical simulations show that the observed groups are not inconsistent with linear, Gaussian and wave fields with the same spectra as the observations. Differences between ocean observations and linear theory are owing to statistical fluctuations in group statistics estimated with the 2.3-h-long data records. One linear analytic model accounts for correlations between two successive waves, and slightly underpredicts the average number of sequential large waves for wave fields with very narrow power spectra. A newly developed extension to Rice better accounts for multiwave correlations, but has only marginally improved accuracy for these data because wave fields with very narrow power spectra rarely occurred. Both approximations overpredict the group lengths for very broad and/or multipeaked power spectra, but are still useful because the errors are small with commonly occurring spectral shapes. Direct numerical simulations, with computational expense between that of the spectral-Kimura and extended-Rice, approximations, yield the best predictions of the observed wave group statistics given a power spectrum, and also provide estimates of the statistical fluctuations of group properties about predicted mean values.

Within- and between-centre variability in the measurement of organic matter digestibility in vivo of cereal straws

Four centres assessed the within- and between-centre variability in measuring the organic matter digestibility in vivo of untreated and ammonia-treated straw using sheep. Three evaluation methods were used: straw fed ad libitum with a nitrogen and sulphur supplement; straw fed with dried grass at maintenance with the digestibility values of the straw calculated by difference; straw fed with two levels of maize germ meal at maintenance. The results were calculated by regression. The largest and smallest within-centre variances were observed using the difference (0.1768) and ad libitum (0.0199) methods, respectively, both of these occurring in the same centre. Significant differences in the predicted mean values for organic matter digestibility were observed between centres (range 0.473–0.531) which could not be accounted for by evaluation method. A significant interaction with ammonia treatment was also seen. The observed differences were unlikely to have led to substantially different nutritional advice in practice, although in this experiment the difference method failed to identify any effect of ammonia treatment.

THE EFFECT OF DRYING TEMPERATURE ON CORN SEED QUALITY

Seed produced on three widely grown public corn (Zea mays L.) inbreds were tested for tolerance to drying injury. Inbred parents A632, B73, and Mo17 were grown in 1979 and 1980. The single cross H99 × H95 was used as a pollinator both years. Random ear samples were collected, to obtain ears with moisture percentages ranging from approximately 50 to 20%, and dried to 12% moisture at 35 °C, 40 °C, 45 °C, and 50 °C. Inbred parents were found to differ in tolerance to high drying temperatures. A632 was the most tolerant to high drying temperatures whereas B73 and Mo17 were relatively intolerant. Field performance of dried seed was similar to that observed in laboratory tests. Combined analyses yielded significant inbred-parent by harvest-moisture by drying-temperature interactions for germination and cold-test emergence percentages. These interactions do not allow for simple recommendations of safe harvest moistures and drying temperatures. Components from the combined analysis that had a P > F of 0.30 or less were then used to predict mean values for A632, B73, and Mo17 germination, cold-test emergence, seedling dry weight and the ratio of shoot to root dry weight. Values for the ratio variable indicated that root development is more susceptible to injury than is shoot development. These predicted values provide seed producers with information on the quality responses that they could expect when seed of A632, B73, or Mo17 is harvested at different moisture contents and dried at different drying temperatures.Key words: Drying, seed quality, Zea mays L.

Correlation of optical propagation near the sea surface with bulk meteorological measurements

Observations of optical propagation and bulk meteorological measurements were made from a tower located off the entrance to Narragansett Bay, RI. Measurements of air and sea temperatures, wind speed, and dew point were used to derive mean values ofC n 2. Then an optical propagation formulation employingC n 2 (height) was used to predict mean values of the spreading of a narrow target line at ranges up to 5 km. Predicted line widths were compared with measured ones. Under conditions of strong instability, mean line-width values agreed to within about ±25%. Under neutral and stable conditions, observations were limited by instrumentation, but predicted and mean measured line-widths agreed within a factor of two. Ratios were formed ofC n 2 values obtained from line-width measurements to corresponding values derived from bulk meteorological measurements under unstable atmospheric conditions. The geometric mean of the set of ratios was 0.94.

Experimental determination of the random lump-age distribution in the boundary layer of the turbulent pipe flow using laser-doppler anemometry

Local velocities in the boundary layer of a fully-developed turbulent water flow in a horizontal, straight, smooth, 50 mm dia. tube were measured at 15, 20 and 30°C, and at Re = 5000, Re = 9500 and Re = 20000 with a laser-Doppler velocimeter, accessory optics and a data processing system. Velocities in axial and radial directions at fixed positions near the wall were measured and their fluctuations were attributed to bursts and background turbulence. Each burst is considered as a spontaneous replacement of a liquid lump on the wall by a fluid entity from the bulk; background turbulence is considered as noise. For the velocity fluctuations in the axial direction an adequate procedure was applied to discriminate between bursts and noise. The values of a large number of time intervals between successively detected bursts were measured and presented in histograms. Further the time-average velocity profile in the boundary layer and the velocity profile near the wall just after the moment that a burst occurs, were determined experimentally The results of these measurements are compared with those predicted by the RSRP-model, based on Danckwerts' concept and recently applied to momentum transfer by Fortuin and Klijn [20]. In the present paper the RSRP-theory is verified by comparing: measured mean values of the time intervals and predicted mean values of the lump ages; the measured time-interval distribution and the predicted random lump-age distribution; the measured velocity profile in a “new” fluid entity on the wall and the predicted profile in a “young” lump; the measured and predicted time-averaged velocity profiles in the boundary layer. Moreover, the behaviour of the fluid near the wall, reconstructed from measured values of the velocities in axial and radial directions around the moment that a burst occurs, agrees with the concept of surface renewal.

Total effective time of the forced expirogram in disease: sources of error and a correction factor.

Effective time of the forced expirogram is a sensitive index for the detection of mild airways obstruction. However, there is evidence that this measurement is not superior to maximum flow rates in the lower half of the forced vital capacity or even FEV1 and FEV1% in some patients suffering from obstructive lung disease. Furthermore we noticed that in some patients with a decrease of the forced vital capacity caused by exacerbation of airways obstruction, the effective time was not appreciably changed. We concluded that this apparent disadvantage of the effective time is the result of the different forced vital capacities. To eliminate this error we transformed the forced expirogram to the equivalent curve that the patient would produce, if his forced vital capacity was equal to the predicted mean value for his age, sex, and height. The derived corrected total effective time seems to have increased sensitivity for detection of small changes in expirograms obtained from the same subject or from different subjects.

Assimilation resistance and affective response in problem solving

In a problem solving experiment, predictions were based upon a theory of motivation and action, the scheme theory, and a psychometric model for the component analysis of rating data, the sector model (Eckblad, 1981; 1980). Pattern guessing tasks were presented to 32 students, 8 to each subject, in individual sessions lasting more than one hour. Number of errors, rated attractiveness, and guessing latencies (the process variables) were recorded during each task. After completion of each task, the affective reaction to it was assessed by means of ratings on six scales, including the scales Pleasant, Interesting, and Complex. On the basis of the sector model, an index of assimilation resistance was computed from the ratings of each task/subject unit, and the index was used to predict mean values and gradients for the process variables. Results show that the sector structure is clearly present in the rating data, that the process variables fit into the structure in the predicted manner, and that mean values and gradients for the process variables differ highly significantly and as predicted among tasks of different levels of assimilation resistance.