High Coefficient Of Variation Values Research Articles

Short Communication: Evaluation of quantitative and qualitative morphological characters of sunflower (Helianthus annuus) germplasm

Purwati RD, Herwati A. 2016. Evaluation of quantitative and qualitative morphological characters of sunflower (Helianthus annuus) germplasm. Biodiversitas 17: 461-465. Sunflower (Helianthus annuus L.) germplasm collection in ISFCRI was characterized aiming to distinguish the morphological characters of each genotype. Based on that information it would be possible to observe the diversity and to choose appropriate parent genotypes for successful hybridization. The investigation was carried out in the Pasirian Experimental Station, Lumajang District, East Java, Indonesia located at 110 m above the sea level (113° E, 8° S) in the 2015 growing season. Thirty-three germplasm accessions were characterized. Each accession was planted in 32 m² plot size with four lines. Fertilizer dose was 75 kg Nitrogen + 30 kg P2O5 + 30 kg K2O per ha. The results showed that the low variation value in some quantitative characters such as seed size, weight of 100 seeds, seeds thickness, plant height, leaf size, ray floret length, bract length, head diameter, the flowering time, and seed oil content. The qualitative characters exhibited high coefficient of variation values with only one exception-pollen formation in sunflower inflorescences. These results indicated that on the base of their qualitative morphological characters, sunflower accessions possessed high diversity. The seed size and seed thickness showed significant positive correlation with 100 seeds weight. These two characters might be used as selection criteria in sunflower breeding programs for appropriate screening of parental genotypes included in hybridizing process aiming the increase of plant productivity.

Commercial Iranian olive cultivars: morphological traits, molecular diversity, and genetic structure

ABSTRACTIran is considered to have a unique gene pool of different fruit and nut species including olive (Olea europaea L.). In this study, we used 22 previously developed microsatellite (simple sequence repeat; SSR) markers for olive to evaluate the level of genetic variation and to produce identification keys for 63 Iranian accessions of olive belonging to 17 groups of cultivars. Based on morphological features, the number of flowers per inflorescence, fruit weights, endocarp weights, oil percentages, and flesh weights per endocarp had the highest coefficient of variation values, indicating the large extent of morphological variability among the 63 Iranian olive cultivars studied. All 22 microsatellite (SSR) markers revealed a high level of polymorphism, with a mean polymorphic information content (PIC) value of 0.511. Analyses of genetic structure among the 63 olive accessions were carried out using model-based methods, which showed a tendency for geographical clustering. Ten SSRs out of the 22 were successful for the identification of unique ID keys for 52 of the 63 accessions. In most cases, there was disagreement between the molecular data and the morphological data. These results could be used to reconstruct and maintain a collection of olive for future breeding programmes.

Comparison of relative abundance indices calculated from two methods of generating video count data

The use of baited remote underwater video to remotely observe fish and generate indices of relative abundance has steadily gained acceptance as a fisheries management tool particularly as survey time series have matured. Because ‘capture’ for this gear is visually derived, fish can possibly be counted multiple times and therefore different methods of estimating site abundances have been developed. We compared the performance of two video abundance estimation techniques, MaxN and MeanCount, by generating relative indices of abundance using a delta lognormal model. We demonstrated high correspondence between standardized indices produced through the years analyzed independent of the species evaluated, indicating there was little change in the information content between indices. Despite the agreement between the indices, estimates for proportion positive and coefficient of variation (CV) showed a general reduction in precision when using the MeanCount method for all species analyzed. Systematic underestimation of proportion positives and high CV values generated using MeanCount is problematic for the use of that abundance estimation method. Individual-based modeling results confirmed that MeanCount is linearly related to true abundance, while MaxN showed a power relationship. However, the MaxN estimate became linear as the area observed was increased in the model from 25% to 100%, which suggests that syncing cameras and generating counts over the entire observed area would eliminate the asymptotic relationship and simplify the use of MaxN estimators. Better understanding of catchability for optical type gears would enhance understanding of the relationship between the generated index and true population abundance, and supply assessment scientist with a clearer understanding of how to incorporate these types of survey data into assessments.

Association between Argyrophilic Proteins of Nucleolar Organizer Regions, Clinicomorphological Parameters, and Survival in Non-Small-Cell Lung Cancer.

We studied argyrophilic proteins associated with nucleolar organizer regions (AgNOR) in non-small-cell cancer. We determined the area index (AI) and coefficient of variation (CV) of AgNOR. AI is associated with the key clinicomorphological parameters within the TNM system: T and N values, greatest tumor dimension up to 3 cm and more, disease stage, histogenesis, and tumor differentiation. CV is associated with T value, greatest tumor dimension up to 3 cm and more, histogenesis, and tumor differentiation. Survival of patients is longer in low AI or CV values versus high AI or CV values, longer in low AI and CV values (−AI/−CV type), shorter in high AI and CV values (+AI/+CV type), and intermediate in opposite AI and CV values (−AI/+CV and +AI/−CV types). Independent predictors in non-small-cell lung cancer include N value, greatest tumor dimension, histogenesis, and CV. Assessment of quantitative values and heterogeneity of AgNOR is important for differential diagnosis and prognosis of non-small-cell lung cancer.

Assessment of Trabecular Bone Yield and Post-yield Behavior from High-Resolution MRI-Based Nonlinear Finite Element Analysis at the Distal Radius of Premenopausal and Postmenopausal Women Susceptible to Osteoporosis

To assess the performance of a nonlinear microfinite element model on predicting trabecular bone yield and post-yield behavior based on high-resolution in vivo magnetic resonance images via the serial reproducibility. The nonlinear model captures material nonlinearity by iteratively adjusting tissue-level modulus based on tissue-level effective strain. It enables simulations of trabecular bone yield and post-yield behavior from micro magnetic resonance images at in vivo resolution by solving a series of nonlinear systems via an iterative algorithm on a desktop computer. Measures of mechanical competence (yield strain/strength, ultimate strain/strength, modulus of resilience, and toughness) were estimated at the distal radius of premenopausal and postmenopausal women (N = 20, age range 50-75) in whom osteoporotic fractures typically occur. Each subject underwent three scans (20.2 ± 14.5 days). Serial reproducibility was evaluated via coefficient of variation (CV) and intraclass correlation coefficient (ICC). Nonlinear simulations were completed in an average of 14 minutes per three-dimensional image data set involving analysis of 61 strain levels. The predicted yield strain/strength, ultimate strain/strength, modulus of resilience, and toughness had a mean value of 0.78%, 3.09 MPa, 1.35%, 3.48 MPa, 14.30 kPa, and 32.66 kPa, respectively, covering a substantial range by a factor of up to 4. Intraclass correlation coefficient ranged from 0.986 to 0.994 (average 0.991); CV ranged from 1.01% to 5.62% (average 3.6%), with yield strain and toughness having the lowest and highest CV values, respectively. The data suggest that the yield and post-yield parameters have adequate reproducibility to evaluate treatment effects in interventional studies within short follow-up periods.

Croton Codiaeum variegatum (L.) Blume cultivars characterized by leaf phenotypic parameters

Croton Codiaeum variegatum (L.) Blume is a popular ornamental foliage plant that displays an anomalous range of variations in its leaf size, shape and color pattern. By fixing such leaf variations, more than 300 cultivars have been produced in the world. Until now, however, only a limited number of studies have been made to describe the leaf phenotypic diversity. Here we investigated the diversity of leaf phenotype in croton cultivars with a numerical taxonomic approach. One-way analysis of variance confirmed significant phenotypic variations in the croton cultivars for 12 quantitative leaf parameters. Among the numerical parameter tested, the leaf index that is the ratio of leaf length to leaf width showed the highest variability. High coefficient of variation values were observed in petiole length, leaf area and leaf down quarter width. In contrast with leaf morphology, the composition of leaf pigments that contribute to leaf coloration did not show diversity. Based on the analyses of the leaf parameters, we clustered the croton cultivars into four major groups. The results of this study provide a numerical basis for classification of croton cultivars. A possible involvement of transposon is discussed in terms of somatic mutation that results in the leaf phenotypic diversity.

Strong ground-motion prediction and uncertainties estimation for Delhi, India

An endeavour has been made in the present study to estimate the uncertainties in strong ground-motion estimation for Delhi region. The strong ground motion (SGM) has been estimated using the logic-tree approach with equal weights chosen for the branches of the logic tree because a scientific preference has not yet been developed for the area. Coefficient of variation (COV) maps have been generated along with the mean SGM which aid in visualizing the effect of our lack of knowledge on the final results and highlight those areas where improved scientific understanding can have an impact on future hazard maps. Monte Carlo simulation has been sued to consider the effect of the variation in the seismic hazard parameters. The spectral ground generated for various return periods suggests higher values in the north-west region with a decreasing trend towards the south-east part of Delhi. The hazard gradient is highest at spectral acceleration (Sa) 0.1 s and lowest at spectral acceleration (Sa) 1.0 s for all return periods. The highest COV values (~0.60) were observed in case of PGA while lowest COV values (~0.15) were observed for spectral acceleration (Sa) 0.3 s at all return periods. One of the conspicuous observations is that the trends of COV maps have been found to be governed by the boundaries of the seismogenic sources. While COV values are governed mostly by Line Sources in smaller return and time periods, in higher return periods trend of the COV maps were found to be governed by the boundaries of the Areal Sources.

Influence of Pupil Dilation on Repeatability of Scanning Laser Polarimetry With Variable and Enhanced Corneal Compensation in Different Stages of Glaucoma

To evaluate the influence of pupil dilation on repeatability of scanning laser polarimetry with variable (GDx-VCC) and enhanced (GDx-ECC) corneal compensation, in different stages of glaucoma. One eye of each of 37 Caucasian participants [14 healthy and ocular hypertensive subjects with mean deviation (MD) <2 dB, 11 glaucoma patients with MD 6 to 12 dB, and 12 glaucoma patients with MD >15 dB] was imaged 5 times with both GDx-VCC and GDx-ECC, before and after pupil dilation. No statistically significant alteration was found for any parameter or most coefficients of variation in any group, or in the total study population, due to pupil dilation. Intraclass correlation was similar with both compensation techniques: it varied between 98.5% and 99.2% before, and 97.3% and 99.1% after pupil dilation for all participants. Intrasession variability was below 6 mum for all parameters and all groups irrespective of corneal compensation and pupil dilation. By using GDx-ECC, a statistically significant trend for higher coefficient of variation values in more severe stages of glaucoma was found, irrespective of pupil dilation (Jonckheere-Terpstra test, P<0.026, for all parameters). With GDx-VCC this trend was not seen for 2 of the 3 parameters before pupil dilation, but did appear for all parameters in mydriasis (P<0.002). Repeatability of GDx-VCC and GDx-ECC is similar, and is satisfactory for clinical purposes; it is only minimally influenced by pharmacological mydriasis. However, repeatability of the measurement decreases with increasing severity of glaucoma. This characteristic is better detectable with GDx-ECC than with GDx-VCC.

Reproducibility and repeatability of measuring the electrical impedance of the pregnant human cervix-the effect of probe size and applied pressure

BackgroundThe utility of cervical electrical impedance spectroscopy (EIS) as a diagnostic tool is being investigated in clinical trials. We sought to assess the reliability of two different sizes of tetrapolar probes used in measuring cervical impedance.MethodsCervical transfer impedance was measured at 14 frequencies between 76 and 625 000 Hz from 11 pregnant subjects at term. Repeated measurements were taken with two probes (3 mm and 12 mm diameter) applied softly (approximately 0.7 Newton of force), and firmly (approximately 2.2 Newton) to the surface of the cervix by two observers. The intra-class correlation coefficient (ICC), coefficient of variation (CV) and repeatability standard deviations (SD) were derived from these measurements and compared.ResultsMeasurements taken by one observer were highly repeatable for both probes as demonstrated by high ICC and low CV values. Probe performance was improved further by firm application. Firm application of the 3 mm probe resulted in ICC values that ranged from 0.936 to 0.986 (p = 0.0001) and CV values between 1.0 and 3.4%. Firm pressure with the 12 mm probe resulted in ICC values that ranged between 0.914 and 0.988 (p = 0.0001) with CV values between 0.7 and 2.1%. In addition, the repeatability SD was low across all frequencies implying that there was low intra-observer variability. Measurements taken by 2 observers with firm application of the 12 mm probe demonstrated moderate reproducibility between 9.8 and 156 kHz, the frequency range in which previous clinical studies have shown predictive association between high cervical resistivity and vaginal delivery: ICC values ranged between 0.528 and 0.638 (p < 0.05), CV values were between 3.3 and 5.2% and reproducibility SD values were also low. In contrast the 3 mm probe demonstrated poor reproducibility at all study frequencies.ConclusionMeasuring cervical resistivity by a single observer with both the 3 and 12 mm probes is highly repeatable whilst inter-observer reproducibility is poor with the 3 mm probe but moderately good when the 12 mm probe is firmly applied to the cervix in the frequency range 9.8 to 156 kHz, consistent with our observations of probe performance in clinical trials.

Novel Scaled Bioequivalence Limits with Leveling-off Properties

(1) To develop novel scaled bioequivalence (BE) limits with levelling-off properties based solely on variability considerations and (2) to evaluate their performance in comparison to the classic unscaled BE limits 0.80-1.25, the expanded BE limits 0.75-1.33 and the recently proposed Geometric Mean Ratio (GMR)-dependent scaled BE limits BELscW (Karalis et al., Eur. J. Pharm. Sci., 26:54-61, 2005). Two model functions were used to ensure the gradual change of the BE limits from a starting value towards a predefined plateau value. Plots of the new BE limits and extreme GMR values ensuring BE as a function of the coefficient of variation (CV) were constructed. Two-period crossover BE studies with 12, 24, or 36 subjects were simulated assuming CV values from 10 to 60%. Power curves were constructed by recording the percentage of accepted BE studies as the true GMR was raised from 1.00 to 1.50. The percentage of the true GMR within the simulated BE limits vs. true GMR was used to evaluate the estimation accuracy of the scaled methods. Depending on the parameters' values of the model functions, the scaled BE limits exhibit different performance. Four new scaled BE limits, showing favourable performance for the evaluation of average BE are presented. At low variability levels two of the novel BE limits show similar performance to the 0.80-1.25 criterion, while the other two (as expected from their design) appear to be less permissive. At high CV values (30, 40%) all new BE limits exhibit much higher statistical power than the 0.80-1.25 criterion. They show almost identical behavior with the expanded 0.75-1.33 limits and appear to be less permissive than BELscW. Finally, the percentage of the true GMR within the simulated BE limits vs. true GMR shows a sharp decline. Due to the absence of the GMR factor in the model functions a more accurate estimation of the new scaled BE limits, compared to BELscW, is observed. The new scaled BE limits appear to be highly effective at all levels of variation investigated and present satisfactory estimation accuracy.

General and Spatial Variability of Soil Under Vetiver Grass Strips

ABSTRACT The variability of surface soils on the same field is influenced largely by soil erosion and runoff deposition. The general and spatial variability of soils on runoff plots under the influence of vetiver grass strips (VGS) was therefore studied using both the conventional “Fisher” statistics and geostatistics. The focus was on safe use of vetiver system for combating land degradation in view of its various advantages. The overall objective was to quantify the variability in relation to VGS effects on the soil and its influence on other plants. The VGS were established at 20 m spacing two years earlier, hence some soil had accumulated on the upper slope side at a mean rate of 71.0 mm per year. There were greater faunal activities around the VGS than elsewhere in the field. The study area was on a 5% slope and grid (5 m × 3 m) systematic sampling was used; the samples were collected at depths of 0-5 cm and 5-10 cm were processed and analyzed physically and chemically. Static soil properties such as total sand (ranged 712 to 866 g kg−1) and bulk density (1.24 to 1.51 g cm−3) had low co-efficient of variation (CV) values (CV < 15%), and dynamic soil properties, which could easily be influenced by management, (such as available phosphorus, P, and silt; ranging from 2.85 to 13.2 mg kg−1 and 64 to174 g kg−1, respectively) had high CV values of 35% to 70%. Gravel content (50.4-175.1 g kg−1) was not significantly different amongst plots in the field. All the parameters analyzed followed a normal frequency distribution. For the geostatistics, considered along a south-north transect only, the semivariances approached the overall variance, Ko, within distance lags of 5-20 m for clay at 5-10 cm depth, total sand and soil pH at 0-5 cm depth. Values beyond the variance distances, Ko, were considered independent of each other. Bulk density, available P, and soil pH revealed no spatial dependence on the VGS effect. The results of the effects of VGS on properties of soils bound by it showed that clay and bulk density were less with VGS than without; 83.83 g kg−1 clay with VGS and 90.5 g kg−1 without VGS; bulk density of 1.40 g cm−3 with VGS and 1.43 g cm−3 without VGS both at 0-5 cm depth. The reverse was observed for sand content, though; their effects were linked to slope, erosion and pedogenic factors rather than VGS. Among the chemical properties, organic carbon (OC) and total nitrogen (TN) were higher in parcels of land bounded by the VGS than those without. At 5-10 cm depth, OC was 14.25 g kg−1 with VGS and 11.35 g kg−1 without. Similar rise was observed for soil pH; 5.61 with VGS and 5.25 in the control without VGS at 0-5 cm depth. In contrast, available P was lower in lags bounded by VGS than those without VGS. The use of the VGS technology in combination with mechanical measures such as along water ways, gully embankments, roadsides and sloppy farm-lands to protect and rehabilitate marginal lands to facilitate crop production, and the integration of soil variability with problem solving were recommended. It was concluded that since VGS did not cause any significant difference in the soil physical properties it can be safely used as an environmentally-friendly natural resource to improve and protect farmlands and infrastructures. However, the application of geostatistics was not necessary because of the small volume of the data involved, conventional statistics were enough to fully quantify the variability.

Exigência nutricional de sódio para frangos de corte de 1 a 21 dias de idade

Com o objetivo de determinar as exigências em sódio para pintos de corte machos e fêmeas, durante a fase inicial, foram utilizados 800 pintos, sexados, da marca comercial Avian Farms, no período de 1 a 21 dias de idade, com peso médio inicial de 40,5 g, submetidos a uma dieta basal (3.000 kcal EM/kg e 21,1% de PB) deficiente em sódio (0,017%), suplementada com NaCl, correspondente aos níveis 0,077, 0,137, 0,197, 0,257 e 0,317% de sódio total. O delineamento utilizado foi o inteiramente casualizado, em arranjo fatorial 5x2 (níveis de sódio x sexo), com quatro repetições e 20 aves por unidade experimental. Foram avaliados o ganho de peso (GP), o consumo de ração (CR), a conversão alimentar (CA), o peso absoluto (PAA) e relativo (PRA) de adrenal, o rendimento (RC) e a matéria seca (MS) de carcaça, com as exigências estimadas por meio do modelo de regressão polinomial. Os níveis suplementares de sódio influenciaram GP, CR, CA e PRA, em ambos os sexos, não ocorrendo efeito significativo dos níveis estudados sobre PAA, RC e MS. Demonstrou-se que as avaliações biométricas (peso das adrenais) não são apropriadas para estudos de exigência, por causa do alto coeficiente de variação obtido no estudo. Com base nas características de desempenho, as exigências mínimas recomendadas de sódio, estimadas pelo modelo de regressão quadrática, foram de 0,256 e 0,255%, para machos e fêmeas, respectivamente.

Quantal variability at glutamatergic synapses in area CA1 of the rat neonatal hippocampus.

Quantal variability was determined at glutamatergic synapses in the neonatal (postnatal days 1-7) rat hippocampal slice preparation. Synaptic AMPA and NMDA quantal EPSCs were recorded from CA1 pyramidal neurones using the whole-cell, or perforated, patch-clamp technique. Release was evoked by minimal stimulation using brief trains (10 impulses, 50 Hz), and various tests ascertained that this stimulation activated single release sites releasing single vesicles. Both AMPA and NMDA quantal responses at a given release site varied considerably in magnitude, the coefficient of variation (CV) among the synapses averaging 0.39 and 0.30, respectively. This variability differed among the synapses, from 0.2 to 0.7, and 0.10 to 0.50, respectively, and CV values of AMPA responses co-varied with those of the NMDA responses. Both for AMPA and NMDA, low CV values were associated with a Gaussian distribution of EPSC peak values, whereas synapses with high CV values displayed distributions skewed towards lower values. Analysis of successive NMDA responses during a train revealed a considerable degree of non-saturation of NMDA receptors by a single vesicle. The results are compatible with a quantal variability based, to a large extent, on non-saturated AMPA and NMDA responses fluctuating as a function of the amount of transmitter released from each vesicle.

Dynamics of membrane excitability determine interspike interval variability: a link between spike generation mechanisms and cortical spike train statistics.

We propose a biophysical mechanism for the high interspike interval variability observed in cortical spike trains. The key lies in the nonlinear dynamics of cortical spike generation, which are consistent with type I membranes where saddle-node dynamics underlie excitability (Rinzel & Ermentrout, 1989). We present a canonical model for type I membranes, the theta-neuron. The theta-neuron is a phase model whose dynamics reflect salient features of type I membranes. This model generates spike trains with coefficient of variation (CV) above 0.6 when brought to firing by noisy inputs. This happens because the timing of spikes for a type I excitable cell is exquisitely sensitive to the amplitude of the suprathreshold stimulus pulses. A noisy input current, giving random amplitude "kicks" to the cell, evokes highly irregular firing across a wide range of firing rates; an intrinsically oscillating cell gives regular spike trains. We corroborate the results with simulations of the Morris-Lecar (M-L) neural model with random synaptic inputs: type I M-L yields high CVs. When this model is modified to have type II dynamics (periodicity arises via a Hopf bifurcation), however, it gives regular spike trains (CV below 0.3). Our results suggest that the high CV values such as those observed in cortical spike trains are an intrinsic characteristic of type I membranes driven to firing by "random" inputs. In contrast, neural oscillators or neurons exhibiting type II excitability should produce regular spike trains.

Quantitative and qualitative analysis of the ascendent frequency whistles of tucuxi, Sotalia fluviatilis, in the Sepetiba Bay, Rio de Janeiro, Brazil

Sotalia fluviatilis was the only cetacean species observed in all 16 boat surveys (82 h) conducted in the Sepetiba Bay (22° 58′, 44° 02′W), between December 1993 and August 1995. During the boat survey of 5 January, 1995—a very calm day (Beaufort = 1)—it was possible to make good subaquatic sound recordings (30 min) of a group of ca. 20 young and subadult dolphins. As there is little bioacoustic information on tucuxi, sonogram analysis was used to characterize the tucuxi’s whistles of ascendent frequency. The qualitative analysis resulted in 866 whistles divided in 48 types. Some of these sonograms shapes match the ones presented by other cetacean species sonograms (Tursiops truncatus, Delphinus delphis, and Globicephala macrorhynchus). The quantitative analysis was based on: number of harmonics; number of inflexions; beginning, final, maximum, and minimum frequecies; duration; and frequency modulation. Minimum, maximum, and average values, standard deviation, and coefficient of variation were calculated for each type of whistle. The S. fluviatilis whistles are extremely diverse (high coefficient of variation values for each type) and frequent (38.5 whistles/min), seeming to have an important role in social relations among these animals. Such whistle diversity and quantities could be explained by the composition of the dolphin group, i.e, it was exclusively formed by young and subadult animals.

Quantitative and qualitative analysis of the descent, up–down, and down–up frequency whistles of tucuxi, Sotalia fluviatilis, in the Sepetiba Bay, Rio de Janeiro, Brazil

Sotalia fluviatilis was the only cetacean species observed in all 16 boat surveys (82 h) conducted in the Sepetiba Bay (22° 58′S, 44° 02′W), between December 1993 and August 1995. Previously, S. fluviatilis whistles were bioacoustically poorly characterized. The objective of this research was a quali–quantitative characterization of tucuxi’s acoustic emissions of descent, up–down, and down–up frequency. The sound analysis was based on sonograms from 30 min of a subaquatic recording obtained on 5 January, 1995. The qualitative analysis resulted in 390 whistles classified in 3 subclasses (descent, up–down, and down–up frequency), 21 types, and 46 subtypes. The quantitative analysis was based on: number of harmonics; number of inflexions; beginning, final, maximum, and minimum frequencies; duration; and frequency modulation. Minimum, maximum, and average values, standard deviation, and coefficient of variation were calculated for each type and subtype of whistle. The S. fluviatilis whistles are extremely diverse (high coefficient of variation values for each subclass, type, and subtype) and frequent (38.5 whistles/min), seeming to have an important role in the social relations among these animals. Such whistle diversity and quantities could be explained by the composition of the dolphin group, i.e., it was exclusively formed by young and subadult animals.

Seasonal variation in the circadian rhythm of pulmonary function in stable asthmatic children who have nearly outgrown their asthma.

To study whether nocturnal bronchial obstruction changes during the year, we assessed the circadian FEV1 variation during four consecutive seasons in 20 children (12 boys; aged 9-12 years) with episodic asthma who were outgrowing their asthma. FEV1 was determined every 4 h between 10:00 and 10:00 during two consecutive days. The last six FEV1 values were submitted to cosinor and coefficient of variation (CV) analyses. The seasonal means (SD) in the group 24 h percent predicted FEV1 was 85.5 (11.4), 81.2 (10.6), 86.0 (11.6), and 82.2 (14.0)% during spring, summer, autumn, and winter, respectively. The difference between the summer and autumn FEV1 values was statistically significant (p < 0.05). The mean (SD) of the circadian amplitude values was 4.1 (4.3), 6.0 (3.8), 4.9 (3.4), and 7.2 (4.1)% during spring, summer, autumn, and winter, respectively. The difference in amplitude between the spring and winter and between the autumn and winter values was statistically significant (p < 0.05). CV values of 48 of the 80 (60%) circadian FEV1 time series exceeded the average CV of 5% observed in nonasthmatic children studied in our laboratory. There was an unequal distribution during the year in elevated CV values; 6, 17, 10, and 15 of the high CV values occurred, respectively, in the spring, summer, autumn, and winter. These results suggest that nocturnal bronchial obstruction may change seasonally in terms of severity and amplitude in children who have nearly outgrown their asthma.

Variability of grip strength during isometric contraction.

The use of measures of strength variability as a means of determining sincerity of effort is becoming a more common practice, particularly in medico-legal and rehabilitation settings. The stability of such variability measures, however, has not been documented. This research investigated, in two studies, the trial-to-trial variability of grip strength under maximal and submaximal effort conditions. In the first study, 63 subjects were asked to give 100% grip effort, and in the second study 40 subjects from the original group were asked to give 50% grip effort. The Jamar hand dynamometer was used to measure grip strength in both experiments, and a coefficient of variation (CV) was calculated for every three repeat measures at each handle position. Testing was conducted on two separate occasions for both experiments. Although the interoccasion reliability of grip strength was very high, in comparison, the CV was not stable over test occasions, with interoccasion reliability indices close to zero. Factors significantly influencing CV were effort level, with submaximal effort producing larger CVs, and gender, with females having greater strength variability. If the rule is applied that one or more CVs above the 7.5% cut-off value could indicate submaximal effort, then for this sample of subjects giving maximal effort, 97% of females and 64% of males would be misclassified. Applying a single CV classification cut-off value to a mixed sample of subjects appears to unfairly discriminate against the females. Further research into the factors associated with high CV values is essential before the CV can be used with any confidence in a clinical setting as a method for determining sincerity of effort.

Responses of pigeon horizontal semicircular canal afferent fibers. II. High-frequency mechanical stimulation.

1. The horizontal semicircular canals of anesthetized (barbiturate/ketamine) pigeons were mechanically stimulated by the use of a piezoelectric micropusher that provided controlled indentation of the surgically exposed membranous horizontal semicircular duct. 2. Extracellular action potentials from single horizontal semicircular canal afferent (HCA) fibers were recorded during sinusoidal mechanical stimulation. This method of stimulation was shown in the companion paper to produce equivalent responses to those produced by rotation for frequencies ranging from 0.01 to 10 Hz. 3. Sinusoidal mechanical stimulation produced clearly entrained action potentials in some HCA fibers up to a frequency of 400 Hz (highest stimulus frequency tested), with stimulus probe displacements of +/- 1.0 and +/- 2.5 microns. Thirty-four HCA fibers were thoroughly studied. 4. For most HCA fibers, the number of action potentials per stimulus cycle decreased as stimulus frequency increased, until only one action potential per stimulus cycle was elicited. The point at which only one spike per stimulus cycle was observed was dependent on both the fiber's resting mean discharge rate (MDR) and the fiber's coefficient of variation (CV) obtained during the MDR. 5. Dynamic response properties of individual HCA fibers were found to be correlated with the fiber's CV and the resting level MDR. Neurons with lower CV values had less adaptation, higher short time constants, and lower high corner frequencies than did neurons with high CV values. For a given CV class of HCA fibers, neurons with higher MDRs had more enhanced gains and more advanced phase shifts at high stimulus frequencies than did neurons with lower MDRs. 6. Transfer function parameters affecting the dynamics of the high-frequency response were derived from the mean gain and phase shift values of regular-, intermediate-, and irregular-firing HCA fibers. Best-fit short time constant (tau S) values of 4.6, 1.9, and 2.0 ms; hair cell membrane time constant (tau M) values of 10.3, 13, and 7 ms; excitatory postsynaptic membrane time constant (tau E) values of 0.8, 0.4, and 0.5 ms; and synaptic delay time constant (tau D) values of 0.5, 0.5, and 1.4 ms were determined for regular, intermediate, and irregular classes of HCA fibers, respectively. 7. The values of 4.6, 1.9, and 2.0 ms derived for the regular, intermediate, and irregular afferents would suggest upper-corner frequencies of 35, 84, and 80 Hz for these classes of HCA fibers, respectively.

Ultrasonic tissue characterization of the placenta: is it of clinical value?

Placentas of 84 antenatal patients have been examined throughout pregnancy (14-40 weeks of gestation). The coefficient of variation (the standard deviation divided by the mean) of echo-peak amplitude distributions obtained from placental images was used to characterize the placentas in different groups. Placentas of smokers yielded higher coefficient of variation values throughout pregnancy (P less than 0.05). This placental texture index was significantly lower for nonsmoking mothers of low-birth-weight babies after 30 weeks of gestation (P less than 0.001). Quantitative analysis of placental appearance may be of clinical value in selecting nonsmoking women at risk for low-birth-weight babies during the third trimester.