Derive Mean Values Research Articles

Stochastic approach to the derivation of emission limits for wastewater treatment plants

Stochastic approach to the derivation of WWTP emission limits meeting probabilistically defined environmental quality standards (EQS) is presented. The stochastic model is based on the mixing equation with input data defined by probability density distributions and solved by Monte Carlo simulations. The approach was tested on a study catchment for total phosphorus (P(tot)). The model assumes input variables independency which was proved for the dry-weather situation. Discharges and P(tot) concentrations both in the study creek and WWTP effluent follow log-normal probability distribution. Variation coefficients of P(tot) concentrations differ considerably along the stream (c(v)=0.415-0.884). The selected value of the variation coefficient (c(v)=0.420) affects the derived mean value (C(mean)=0.13 mg/l) of the P(tot) EQS (C(90)=0.2 mg/l). Even after supposed improvement of water quality upstream of the WWTP to the level of the P(tot) EQS, the WWTP emission limits calculated would be lower than the values of the best available technology (BAT). Thus, minimum dilution ratios for the meaningful application of the combined approach to the derivation of P(tot) emission limits for Czech streams are discussed.

The mean value of derivative of phase modulus of the harmonic signal and Gaussian noise sum

The expression for mean value of derivative of phase modulus of the signal and narrow-band Gaussian noise sum, when signal’s frequency does not coincide with center frequency of noise, is obtained. The derivative of phase is a quotient of random functions and sum envelope.

Cardiac Chamber Volumes, Function, and Mass as Determined by 64-Multidetector Row Computed Tomography: Mean Values Among Healthy Adults Free of Hypertension and Obesity

We derived mean values for cardiac dimensions, volumes, function, and mass in a normotensive nonobese population free of cardiovascular disease. Multidetector computed tomography (MDCT) permits study of cardiac chamber size, function, and mass. Age- and gender-specific mean values are not available. A total of 103 normotensive, nonobese adults (43% women, age 51 +/- 14 years) who presented consecutively to 2 medical centers for clinically indicated MDCTs with neither history of nor MDCT evidence of significant cardiovascular disease were studied for left ventricular (LV) and right ventricular (RV) end-systolic (ES) and end-diastolic (ED) linear dimensions and volumes; LV and RV ejection fraction (EF), and LV mass (LVM); and left atrial (LA) and right atrial (RA) end-systolic volumes (LAESV and RAESV, respectively) by 1-dimensional (1D), 2-dimensional (2D), and 3-dimensional (3D) measurements. The LV volumes using 3D techniques were lower than 2D techniques (LVEDV mean 144 +/- 71 ml vs. 150 +/- 70 ml), with higher LVEF (63 +/- 15% vs. 57 +/- 13%) (p < 0.001 for both). Mean LVM/height(2.7) was 24.3 +/- 11.0 g/m(2.7) and mean relative wall thickness was 0.16 to 0.44. Evaluation by 20 versus 10 cardiac phases resulted in higher LVEF (mean difference: 3.4 +/- 9.0%, p < 0.001). For LVEDV, interobserver (r = 0.99, p < 0.001) and intraobserver (r(2) = 0.97, p < 0.001) correlations were high. Mean RVEDV was 82 +/- 57 ml and RVEF was 58 +/- 16. The LAESV determined by 3D techniques was higher than by that determined by 2D methods (102 +/- 48 ml vs. 87 +/- 57 ml, p = 0.0003). The RAESV determined by 3D techniques was 111.9 +/- 29.1 ml. The LV size and LVM were greater in men than in women (p < 0.01). The LV size declined with age (p < 0.01), but LVM did not. This study establishes age- and gender-specific values for LV, RV, LA, and RA size, function, and mass in adults free of cardiovascular disease, hypertension, and obesity using 1D, 2D, and 3D methods. These data can be used as a reference for future MDCT studies.

Attenuation in the uppermost inner core from PKP recordings at African seismological stations

The attenuation factor QP at the top of the inner core is evaluated by using the amplitude spectral ratio of PKPdf and PKPbc phases observed at African stations (BGCA mostly), from strong deep earthquakes in the Pacific Ocean area. The maximum depth of penetration of the PKPdf phase into the inner core (IC) is roughly 377 km, and the sampled region of IC is centered beneath the Southern Indian Ocean. The derived mean value of QP is 249 ± 31 (95% confidence level) in the frequency range 0.2–2 Hz, where no frequency dependence of attenuation has been reliably observed. By using Student’s t-test, we show that the value is statistically significantly different (with a probability greater than 95%) from other mean values of Q derived by using the same method, for both the western (180 °W to 40 °E) and eastern (40 °E to 180 °E) hemispheres of the IC. The decrease of Q with the radius of the turning point (denoted by rTP), according to QP = 840 − 0.62 rTP, has a moderate statistical support (the R-squared value is 38%). A slightly increase of Q as a function of the angle of the PKPdf path within the inner core with respect to the Earth’s spin axis is observed, in agreement with various investigations performed in the time domain. However, the value of the anisotropy, if any, is suggested to be around 3%.

Delivery of High-Tech Home Care by Hospital-Based Nursing Units in Quebec: Clinical and Technical Challenges

The role that hospital-based nurses should play in the delivery of high-tech home care, and how they should be supported in that role, are topics that remain understudied. Our research objective was to document how hospital-based nursing teams perceive and deal with the clinical and technical challenges associated with the provision of high-tech home care. Four home care interventions were selected: antibiotic intravenous therapy, parenteral nutrition, peritoneal dialysis and oxygen therapy. A self-administered survey was sent to all hospital-based units providing these interventions in the province of Quebec, Canada (n = 154; response rate: 70.8%). We used descriptive statistical analyses to derive mean values for scores on either a five- or a six-level Likert scale. Despite variation across the four interventions, our results indicate that while nursing teams believe these interventions increase patients' autonomy, they also recognize that they generate anxiety and impose constraints on patients' lives. Nurses must increase efforts to deal with both clinical and technical challenges and help patients overcome the barriers to appropriate use of home care technologies. While nursing teams generally perceive high-tech home care as beneficial, they still experience significant technical and clinical challenges. Some of these challenges could be addressed by strengthening professional training initiatives, while others require broader home care policy interventions.

Fractal analysis of heart rate variability and mortality in elderly community-dwelling people — Longitudinal Investigation for the Longevity and Aging in Hokkaido County (LILAC) study

Aim. Fractal analysis of heart rate (HR) variability (HRV) has been used as a new approach to evaluate the risk of mortality in various patient groups. Aim of this study is to examine the prognostic power of detrended fluctuation analysis (DFA) and traditional time- and frequency-domain analyses of HR dynamics as predictors of mortality among elderly people in a community. Methods. We examined 298 people older than 75 years (average age: 79.6 years) and 1-h ambulatory ECG was monitored. During the last 10 min, deep respiration (6-s expiration and 4-s inspiration) was repeated six times in a supine position. Time-domain and frequency-domain measures were determined by the maximum entropy method. Scaling exponents of short-term (<11 beats, alpha 1) and longer-term (>11 beats, alpha 2) were determined by the DFA method. Six estimates, obtained from 10-min segments, were averaged to derive mean values for the entire recording span. These average values were denoted Alpha 1 and Alpha 2, estimates obtained during the first 10-min segment Alpha 1 S and Alpha 2 S, and those during the last 10-min segment Alpha 1E and Alpha 2E, respectively. The LILAC study started on July 25, 2000 and ended on November 30, 2004. We used Cox regression analysis to calculate relative risk (RR) and 95% confidence interval (CI) for all-cause mortality. Significance was considered at a value of P < 0.05. Results. Gender, age and Alpha 2E showed a statistically significant association with all-cause mortality. In univariate analyses, gender was significantly associated with all-cause mortality, being associated with a RR of 3.59 (P = 0.00136). Age also significantly predicted all-cause mortality and a 5-year increase in age was associated with a RR of 1.49 (P = 0.01809). The RR of developing all-cause mortality predicted by a 0.2-unit increase in Alpha 2E was 0.58 (P = 0.00390). Other indices of fractal analysis of HRV did not have predictive value. In multivariate analyses, when both Alpha 2E and gender were used as continuous variables in the same model, Alpha 2E remained significantly associated with the occurrence of all-cause mortality (P = 0.02999). After adjustment for both gender and age, a 0.2-unit increase in Alpha 2E was associated with a RR of 0.61 (95% CI: 0.42−0.90, p = 0.01151). Conclusion. An intermediate-term fractal-like scaling exponent of RR intervals was a better predictor of death than the traditional measures of HR variability in elderly community-dwelling people. It is noteworthy that the longer-term (alpha 2) rather than the short-term fractal component (alpha 1) showed predictive value for all-cause mortality, which suggests that an increase in the randomness of intermediate-term HR behavior may be a specific marker of neurohumoral and sympathetic activation and therefore may also be associated with an increased risk of mortality.

Despinning of the earth rotation in the geological past and geomagnetic paleointensities

Length of day (l.o.d.) values deduced from fossils and tidal deposits suggest that the despinning rate was, on the average, about 5 times smaller during the Proterozoic than during the Phanerozoic and, moreover, that between 250 and 100 million years ago, there was a slight non-linear variation super-imposed on the overall linear trend of the Earth's rotation rate. To explain these observational facts, it has recently been argued that formation of the inner structure of the Earth (mass redistribution within the mantle and/or core formation) had not been fully completed before the Proterozoic, and that the decrease of the inertia moment associated with the evolving terrestrial interior compensated to some extent the rotational effects of tidal friction. There is an another plausible explanation to account for the difference of despinning rates during the Proterozoic and Phanerozoic, namely: the distribution of the continents had been significantly different during these epochs and the world ocean had been much shallower in the Proterozoic than in the Phanerozoic. We used published data for the Phanerozoic, Proterozoic and Archean in order to check whether there had been significant long-term changes of geomagnetic intensity. Our results are based on robust statistical analysis; they indicate that during a time interval coinciding roughly with the Mesozoic, the geomagnetic dipole moment underwent a minimum in a quite similar way as the l.o.d. data. For the Proterozoic (2500–570 million years ago) and the late Archean (3000–2500 million years ago), it is very difficult to draw a conclusion concerning the variation in time of the intensity of the geomagnetic field: the data set we used is incomplete and the statistical scatter is larger than the derived mean value. Nevertheless, we tentatively conclude that the values of the average geomagnetic moment were approximately the same in the Phanerozoic and in the Proterozoic+late Archean, and that there is no significant long-term change in the geomagnetic intensity detectable before the Phanerozoic.

Topography-based screening for previous laser in situ keratomileusis to correct myopia

Purpose To demonstrate the feasibility of developing a screening tool based on corneal topography to detect previous myopic laser in situ keratomileusis (LASIK). Setting Clinical data from a private clinic analyzed in a university setting. Methods Two hundred thirty-three topographies were randomly selected so 1 topography per patient was used: 150 from unoperated corneas and 83 from corneas that had LASIK to correct myopia. The mean surgical correction was −4.40 diopters (D) ± 2.53 (SD) (range −11.00 to −0.38 D). All topographies were performed using an Orbscan II unit (Bausch & Lomb Surgical). The LASIK procedures were performed using a Technolas 217C excimer laser and a Hansatome® microkeratome (Bausch & Lomb Surgical). The algorithms used the mean value of the directional derivative (DT) of the anterior tangential curvature of the cornea in the 2.2 mm radius central disk and the mean value of the anterior elevation (E) with respect to the best-fit sphere in the 0.5 mm radius central disk. Topographies in the testing set (n = 119) were classified as operated if E < 0 (E algorithm) or DT > 0 (DT algorithm) or as unoperated. Results The E algorithm yielded 0% false positives and 16.7% false negatives and the DT algorithm, 6.5% and 7.1%, respectively. For myopia greater than −1.12 D, the DT algorithm provided a 0% false negative rate. The performance of E and DT algorithms, used in combination, was superior to clinical assessment. Conclusion Criteria based on Orbscan II corneal topography are proposed for the detection of previous myopic LASIK performed with a Technolas 217C excimer laser.

Estimation of baseflow residence times in watersheds from the runoff hydrograph recession: method and application in the Neversink watershed, Catskill Mountains, New York

AbstractA method for estimation of mean baseflow residence time in watersheds from hydrograph runoff recession characteristics was developed. Runoff recession characteristics were computed for the period 1993–96 in the 2 km2 Winnisook watershed, Catskill Mountains, southeastern New York, and were used to derive mean values of subsurface hydraulic conductivity and the storage coefficient. These values were then used to estimate the mean baseflow residence time from an expression of the soil contact time, based on watershed soil and topographic characteristics. For comparison, mean baseflow residence times were calculated for the same period of time through the traditional convolution integral approach, which relates rainfall δ18O to δ18O values in streamflow. Our computed mean baseflow residence time was 9 months by both methods. These results indicate that baseflow residence time can be calculated accurately using recession analysis, and the method is less expensive than using environmental and/or artificial tracers. Published in 2002 by John Wiley &amp; Sons, Ltd.

Are Stellar Rotational Axes Distributed Randomly?

Stellar line widths yield values of V sin i, but the equatorial rotational velocities, V, cannot be determined for individual stars without knowledge of their inclinations, i, relative to the lines of sight. For large numbers of stars we usually assume random orientations of rotational axes to derive mean values of V, but we wonder whether that assumption is valid. Individual inclinations can be derived only in special cases, such as for eclipsing binaries where they are close to 90° or for chromospherically active late-type dwarfs or spotted (e.g., Ap) stars where we have independent information about the rotational periods. We consider recent data on 102 Ap stars for which Catalano & Renson compiled rotational periods from the literature and Abt & Morrell (primarily) obtained measures of V sin i. We find that the rotational axes are oriented randomly within the measuring errors. We searched for possible dependence of the inclinations on Galactic latitude or longitude, and found no dependence.

RR Lyrae variables in the globular cluster M 5

We present V-band CCD photometry of 65 RR Lyr variables from the globular cluster M5. We have estimated the basic physical parameters for 16 RRc stars and 26 RRab stars using a Fourier decomposition of the light curves of the variables. The mean values of mass, luminosity, effective temperature and relative helium abundance for the RRc stars are measured to be ${\cal M}=0.54{\cal M}_\odot$, log L = 1.69 T_{eff}=7353 K and Y=0.28, respectively. For the RRab variables the derived mean values of absolute magnitude, metallicity and effective temperature are: M_V=0.81, [Fe/H]=-1.23 and T_{eff}=6465 K. We find that the V amplitude of an RRab star for a given period is a function of metal abundance rather than Oosterhoff type. We find significant problems with the calibration of both the zero point and the scale of the luminosities measured with the Fourier technique. The apparent distance modulus derived from RRc stars is equal to $14.47\pm0.11$ and it is in good agreement with recent determinations. On the other hand distance modulus obtained from the sample of RRab stars (calibrated by the Baade-Wesselink observations of field RR Lyr variables) is significantly smaller and equal to $14.27\pm0.04$

Investigating Three-Dimensional and Rotational Effects on Wind Turbine Blades by Means of a Quasi-3D Navier-Stokes Solver

Three-dimensional and rotational viscous effects on wind turbine blades are investigated by means of a quasi-3D Navier-Stokes model. The governing equations of the model are derived from the 3-D primitive variable Navier-Stokes equations written in cylindrical coordinates in the rotating frame of reference. The latter are integrated along the radial direction and certain assumptions are made for the mean values of the radial derivatives. The validity of these assumptions is cross-checked through fully 3-D Navier-Stokes calculations. The resulting quasi-3D model suggests that three-dimensional and rotational effects be strongly related to the local chord by radii ratio and the twist angle. The equations of the model are numerically integrated by means of a pressure correction algorithm. Both laminar and turbulent flow simulations are performed. The former is used for identifying the physical mechanism associated with the 3-D and rotational effects, while the latter for establishing semiempirical correction laws for the load coefficients, based on 2-D airfoil data. Comparing calculated and measured power curves of a stall controlled wind turbine, it is shown that the suggested correction laws may improve significantly the accuracy of the predictions. [S0098-2202(00)02702-4]

The characterisation of an intertidal sediment from the Cumbrian coastline

The characterisation of an intertidal sediment, containing enhanced levels of radioactivity, collected from the Cumbrian coast of the U.K. by the Laboratory of the Government Chemist for the Department of the Environment is described. A wide variety of radiochemical and instrumental techniques were used including α-spectrometry, β-counting, liquid scintillation counting, γ-spectrometry, X-ray spectrometry and mass spectrometry. To derive mean values of the activity concentrations of radionuclides in the material, use was made of the technique developed by Woods and Munster. This technique first critically evaluates data for technical suitability. Then, to avoid excessive manipulation of data, calculation of the weighted (the statistical weighting is the inverse of the squared uncertainties, limited so that no one result contributes more than 50%) and unweighted means is performed, along with a χ 2 test. If the value of χ 2/( n−1)<2, the weighted mean is accepted, otherwise a choice was made between the weighted or unweighted mean. This is done by considering if the uncertainties of both means overlapped, in which case the weighted mean was accepted and the unweighted mean if not. This enabled the derivation of a mean value, even if the data appeared to be inconsistent. In this paper, the history of the material is reviewed and the data analysis technique delineated. Data are presented for the activity concentrations of 21 radionuclides, with >2 determinations, 3 with 2 determinations and 2 with single determinations. Emphasis is placed where data appeared to be discrepant (e.g. 40K and 137Cs), where widely different measurement techniques were employed (e.g. the actinides), where there were analytical “difficulties” (e.g. uranium) or where the radionuclide is not commonly measured (e.g. 155Eu, 237Np and 241Pu). The material is now available to laboratories as a reference material and it is anticipated that it will be used to validate existing procedures and to research new methods of analysis.

Analyses of Archival [Fe/H] Results for Cool Evolved Stars. II.[Fe/H] Standard Stars

ABSTRACTThis paper is the second in a series based on published values of [Fe/H] for late‐type evolved stars. Only high‐dispersion results are considered here. Such data are used to derive mean values of [Fe/H] for stars that have often been used as [Fe/H] standard stars. For ϵ Vir and β Gem, the mean values of [Fe/H] obtained here are +0.04 ± 0.04 dex and 0.00 ± 0.03 dex, respectively. For α Boo, [Fe/H] is found to be −0.55 ± 0.02 dex. For the Hyades, a mean value of [Fe/H] obtained for giants can be combined with a counterpart published previously for dwarfs. The result is +0.10 ± 0.01 dex. Using available evidence, 0.049 dex is the smallest [Fe/H] difference that can be detected between Hyades giants and Hyades dwarfs. No such difference is found.

Computing local parameters of biquartic interpolatory splines

We present local representations of quartic and biquartic splines which use the function (or mean) values and the values (mean values) of the first derivatives. Continuity conditions are expressed as recurrence relations for these parameters. We complete such systems of equations with proper boundary conditions in an adequate reformulation. We then repeatedly use the one-dimensional algorithm obtained in an algorithm for the two-dimensional problem.

The μ-Phase of Co6.3Nb6.7

The rhombohedral structure of the μ-phase Co 6.30 Nb 6.70, space group R3m, Pearson symbol hR39, was refined from X-ray diffraction data of an obverse-reverse twinned crystal. The Co atoms have distorted icosahedral environments, the Nb atoms have coordination numbers 12, 14, 15 and 16, and configurations typical for Frank-Kasper phases. The structure is quantitatively analysed in terms of the dihedral angles and ranges of the edge lengths of the distorted tetrahedra. It is shown that the derived mean values hardly differ from those calculated for other representatives of tetrahedrally close-packed structure types.

Transformation of a linear wave by a local nonlinear element

We consider the scattering problem for the D'Alembert equation with a local nonlinear sine term, which is a simplest model of a dispersionless transmission line with an inserted Josephson junction. The incident wave is taken in the purely ac form. We demonstrate that, when its amplitude exceeds a certain threshold that depends upon the value of a coefficient in front of the nonlinear term, the transmitted and reflected waves contain both ac and dc components, the latter meaning a nonzero mean value of the time derivative.

Propofol infusion and the suppression of consciousness: dose requirements to induce loss of consciousness and to suppress response to noxious and non-noxious stimuli

We have defined the infusion dose requirements of propofol to suppress consciousness and response to a variety of graded non-noxious and noxious stimuli in 52 unpremedicated patients aged 16-40 yr and 32 patients aged 41-65 yr. They were allocated to receive one of five loading dose-infusion schemes designed to establish stable conditions covering the range from wakefulness, through sedation, to loss of consciousness and anaesthesia. At 10 and 20 min after the loading dose, each patient's response to a graded series of stimuli was recorded. Probit analysis was used to derive mean values (95% confidence interval) for the ED50 and ED95 (as final infusion rate) for loss of response to verbal command at 4.9 (4.7-5.1) mg kg-1 h-1 and 7.9 (7.3-8.8) mg kg-1 h-1, respectively, in the young group and 4.2 (4.0-4.4) mg kg-1 h-1 and 5.8 (5.4-6.4) mg kg-1 h-1, respectively, in the older group. In both groups the dose-response curves for suppression of proprioception, finger counting and perception of light touch in conscious patients were shifted to the left of the curves for loss of consciousness and eyelash reflex. Dose-response curves for noxious stimuli were shifted to the right of those for loss of consciousness.

Mean Values of Derivatives of Modular L-Series

Mean Values of Derivatives of Modular L-Series

Mean value of the electric field gradient in a molecule

The relationship between the mean value of the second derivative of the electrostatic potential of the electronic shell of a molecule on its axis and the first derivative of the energy of the molecule with respect to the internuclear distance has been established.