Reference Values For Variables Research Articles

Observed links between coastal ocean processes and Indian Oil Sardine (Sardinella longiceps) fishery along the southwest coast of India

The annual fishery of the Indian Oil Sardine (IOS), Sardinella longiceps, seems to be influenced by the ambient conditions prevailing in the habitats during their early life-history. The present study is aimed at understanding the putative behaviour of IOS along the southwest coast of India (SWCI) to monsoonal upwelling which triggers surface productivity. Mixed layer temperature is observed to be an indicator of the habitat choice and reproductive performance of IOS. A Multi-Criteria Analysis (MCA) model was envisioned to explain the interannual variability of the IOS fishery. In this model, the coactions of variables such as standardized catch per unit effort (SCPUE) of IOS in the first quarter (January to March), southwest monsoonal upwelling index (SWM-UI), and pre-monsoonal mixed layer temperature (PM-MLT) over three decades from 1985 to 2016 were looked upon as indicators to explain the interannual fluctuations in the fishery. Eight different criteria for eight ranks were assigned using reference values for variables. The model ranks the years based on the respective conditions defined based on the suitability criteria for IOS. The model showed a strong relationship of the variables on the annual IOS fishery and revealed that the higher first quarter SCPUE (>3.678) and SWM-UI (>758.7 kg/m/s) influences the interannual variability of the fishery significantly. The primary causative factor for the collapse of this fishery during 1992-99 was the frequent occurrence or co-occurrence of extreme climatic events such as El Niño, La Niña and Indian Ocean Dipole (IOD). Further, a significant increase (p<0.05) in IOS fishery was observed during 2000-07 due to favourable upwelling conditions along the SWCI. The uncertainties prevailing in a complex tropical ecosystem and associated challenges in resolving a multi-craft-gear fishery were addressed using statistical tools to infer logical explanation on the decline and revival of IOS.

Factoring in the spatial effects of symbolic number representation

Spatial constituents of adult symbolic number representation produce effects of size-value congruity, Spatial Numerical Association of Response Codes (SNARC), and numerical distance. According to behavioral experiments, these effects belong to distinct processing stages. Yet, these effects evoke overlapping responses in both early and late Event Related Potentials (ERPs). To probe whether these overlaps indicate sharing of resources, all relevant stimulus and response conditions were factorially combined in a numerical value comparison task. To secure ERP validity, same numbers were compared against variable reference values. This design resulted in previously unobserved interactions in behavior but inhibited late ERP effects. All effects arose early in the P1 component (around 100 ms) and most showed hemispheric specificity. Independency of congruity and SNARC effects was observed, whereas SNARC and numerical distance were closely intertwined. Differences in hemispheric specificity, rather than stage-wise separation, were key to independence.

Data based online operational performance optimization with varying work conditions for steam-turbine system

One of the most urgent problems facing China today is saving energy in the power industry. Moreover, because the steam-turbine system is a main part of the power unit, its operation is of great significance for energy saving. This paper presents an optimization model for steam-turbine systems based on a data-mining method from an operator’s perspective. The main aim of the proposed methodology is to provide reference values of the independent variables for the operator to minimize heat consumption rate. These were determined based on fuzzy C-means clustering and statistical methods by mining the historical operation data resources with respect to varying load and ambient temperature. The proposed methodology application was implemented as an online optimization system for an on-duty steam-turbine system. The application results showed that the energy savings reached up to 79,000 GJ, which is remarkable. The reference values of variables were helpful for improving the steam-turbine system’s performance.

Reference standards for body fat measures using GE dual energy x-ray absorptiometry in Caucasian adults.

BackgroundDual energy x-ray absorptiometry (DXA) is an established technique for the measurement of body composition. Reference values for these variables, particularly those related to fat mass, are necessary for interpretation and accurate classification of those at risk for obesity-related health complications and in need of lifestyle modifications (diet, physical activity, etc.). Currently, there are no reference values available for GE-Healthcare DXA systems and it is known that whole-body and regional fat mass measures differ by DXA manufacturer.ObjectiveTo develop reference values by age and sex for DXA-derived fat mass measurements with GE-Healthcare systems.MethodsA de-identified sample of 3,327 participants (2,076 women, 1,251 men) was obtained from Ball State University’s Clinical Exercise Physiology Laboratory and University of Wisconsin-Milwaukee’s Physical Activity & Health Research Laboratory. All scans were completed using a GE Lunar Prodigy or iDXA and data reported included percent body fat (%BF), fat mass index (FMI), and ratios of android-to-gynoid (A/G), trunk/limb, and trunk/leg fat measurements. Percentiles were calculated and a factorial ANOVA was used to determine differences in the mean values for each variable between age and sex.ResultsNormative reference values for fat mass variables from DXA measurements obtained from GE-Healthcare DXA systems are presented as percentiles for both women and men in 10-year age groups. Women had higher (p<0.01) mean %BF and FMI than men, whereas men had higher (p<0.01) mean ratios of A/G, trunk/limb, and trunk/leg fat measurements than women.ConclusionThese reference values provide clinicians and researchers with a resource for interpretation of DXA-derived fat mass measurements specific to use with GE-Healthcare DXA systems.

Normal Reference Values for Doppler Echocardiography: Influences of Ageing, Gender and Ethnicity.

Normal Reference Values for Doppler Echocardiography: Influences of Ageing, Gender and Ethnicity.

Current Practices of Measuring and Reference Range Reporting of Free and Total Testosterone in the United States

The evaluation and management of male hypogonadism should be based on symptoms and on serum testosterone levels. Diagnostically this relies on accurate testing and reference values. Our objective was to define the distribution of reference values and assays for free and total testosterone by clinical laboratories in the United States. Upper and lower reference values, assay methodology and source of published reference ranges were obtained from laboratories across the country. A standardized survey was reviewed with laboratory staff via telephone. Descriptive statistics were used to tabulate results. We surveyed a total of 120 laboratories in 47 states. Total testosterone was measured in house at 73% of laboratories. At the remaining laboratories studies were sent to larger centralized reference facilities. The mean ± SD lower reference value of total testosterone was 231 ± 46 ng/dl (range 160 to 300) and the mean upper limit was 850 ± 141 ng/dl (range 726 to 1,130). Only 9% of laboratories where in-house total testosterone testing was performed created a reference range unique to their region. Others validated the instrument recommended reference values in a small number of internal test samples. For free testosterone 82% of laboratories sent testing to larger centralized reference laboratories where equilibrium dialysis and/or liquid chromatography with mass spectrometry was done. The remaining laboratories used published algorithms to calculate serum free testosterone. Reference ranges for testosterone assays vary significantly among laboratories. The ranges are predominantly defined by limited population studies of men with unknown medical and reproductive histories. These poorly defined and variable reference values, especially the lower limit, affect how clinicians determine treatment.

Validation of Two‐Dimensional Methods for Left Atrial Volume Measurement: A Comparison of Echocardiography with Cardiac Computed Tomography

Left atrial volume (LAVol) is an important predictor of cardiovascular outcomes. Different formulas are applied to calculate LAVol using two-dimensional transthoracic echocardiography (2DTTE) with variable reference values. The objective of the study was to evaluate the accuracy of methods to calculate LAVol by 2DTTE or cardiac computed tomography (CT). Overall 177 consecutive patients who underwent both a 2DTTE and retrospective electrocardiogram (ECG)-gated coronary CT angiography (CTA) within 15days were included for this study. LA volume measurements were calculated by 2DTTE and 2DCT using the biplane area-length, biplane Simpson's, prolate-ellipsoid-1 and prolate-ellipsoid-2 methods. These results were compared with those measured by CT using a volumetric method. There was very good correlation between the CT and echocardiographic measures for LAVol, but significant underestimation of the echocardiographic methods when compared to the reference standard (33.5%, 39.1%, 48.1%, and 53.2% for the biplane area-length, biplane Simpson's, prolate-ellipsoid-1, and prolate-ellipsoid-2 methods, respectively). The biplane area-length method using 2DTTE had the closest volume estimation of all echocardiographic methods to the reference standard (67.6±25.5mL vs. 106±35.5mL, r=0.712). Similarly, the biplane area-length method using CT most accurately predicted LAVol (103.3±36.0mL, r=0.965). Compared to CT, 2DTTE provides reasonable assessment of LAVol, although all measurement methods underestimate LAVol. For both 2DTTE and CT, the biplane area-length method appears to provide the most accurate 2D estimate of LAVol.

Temporal-spatial gait analysis by use of a portable walkway system in healthy Labrador Retrievers at a walk

To establish a protocol to collect temporal-spatial gait analysis variables by use of a portable walkway system in Labrador Retrievers at a walk and to determine reference values. 56 healthy Labrador Retrievers. 6 passes across the walkway (3 passes in each direction) were recorded. Inclusion criteria for a pass were that the dog was at a walk (velocity, 60.0 to 90.0 cm/s) and had minimal head turning. The first 3 passes that met the inclusion criteria were analyzed for each dog. Mean stride length was 88.4 cm. Mean stance time (ST) of forelimbs and hind limbs was 0.62 and 0.56 seconds, respectively. Mean stance time percentage (ST%; proportion of stance time to total gait cycle time) for forelimbs and hind limbs was 55.6% and 50.2%, respectively. Mean total pressure index (TPI) of forelimbs and hind limbs was 27.1 and 17.4, respectively. Mean number of sensors (NS) activated by each paw strike of forelimbs and hind limbs was 17 and 13, respectively. Mean forelimb-to-hind limb symmetry ratios were 1.11 (ST), 1.10 (ST%), 1.62 (TPI), and 1.37 (NS). Symmetry ratios for left limbs to right limbs, left forelimb to right forelimb, and left hind limb to right hind limb were 1.00. A protocol for collection of temporal-spatial gait analysis variables with a portable walkway system in Labrador Retrievers at a walk was developed, and reference values for variables and symmetry ratios were reported. Further research will determine the extent to which symmetry ratios differ in dogs with orthopedic disorders.

On-Line Identification of Process Dynamics

Two methods similar to regression analysis are applied to the estimation of parameters in a dynamic process equation. One method uses a residual based directly on the differential equation for the process model. The second method forms the residual from the integro-differential equations derived by integration of the original differential equation with respect to time. The two methods are shown to be complementary in their sensitivity to process and measurement disturbances as well as to errors in the estimate of the process variable reference values. Certain parameters that are very sensitive with one method are shown to be much less sensitive with the other method. A combined method is developed which utilizes each one of the constituent techniqtues to estimate the parameter for which it has the highest accuracy. This not only permits identification with higher overall parameter accuracy, but also under many practical circumstances gives a convergent solution when one of the constituent methods would give a diverging solution having no practical value for updating control coefficients in an adaptive controller. It is shown that the estimate of the magnitude of a pole in a transfer function can be significantly improved by prefiltering the process input and output data with the same lowpass filter. The paper presents a theoretical and experimental evaluation of the identification methods. Formulas are derived for the variances of the parameters permitting an estimation of the parameter accuracy in a particular test. The test data used has been collected from different control loops on paper machines. The disturbance level on some of the variables is very stroang and a test signal-to-noise ratio as low as 0.5 can be encountered. The method is currently used in routine operation in adaptive paper machine control. It is in use on four control loops and has been tested on several other loops as well.