A univariate and multivariate examination of measurement error in anthropometry

Replicate anthropometric measurements on 20 male and 22 female Eskimos were examined using analysis of variance, product-moment correlation coefficients, and canonical variates with Mahalanobis' D² distances. Analysis of variance indicated that 12 of the 16 variables could be measured comparably by two investigators. Those variables with readily defined endpoints yielded the highest correlations between the results of two anthropometrists. The multivariate analysis demonstrated a high level of discrimination between two sets of data taken on the same group of subjects. This suggests that population comparisons using data from two or more investigators could be significantly affected by measurement error.     

Radiological anthropometry of the hand in Turner's syndrome.

Metacarpal-phalangeal (M-P) lengths, metacarpal sign, and carpal angle were studied using 142 pairs of hand X-rays from 81 individuals with Turner's syndrome age 6 to 25 years. Left M-P lengths, grouped by bone age, were compared with normal female standards and Z-score pattern profiles calculated for each bone age. Differences between Turners and normals in most M-P lengths increased with age, particularly after puberty. Calculation of inter-individual and intra-individual variability yielded good evidence for a M-P pattern profile typical of Turner's syndrome, with increasing growth deficiency from distal to proximal and lateral to medial. The incidence of positive metacarpal sign was 33.8%, with no significant difference between XO and non-XO Turners. It did not appear that M4 ceased growth prematurely, suggesting that short M4 is not the result of early epiphyseal fusion. Carpal angle, reported to be abnormally decreased in Turners, was not found to differ from normal. There was no difference between right and left sides or between XO and non-XO Turners, but carpal angle did decrease significantly with both decreasing ulnar deviation in positioning of the hand and increasing age. In the latter respect Turners differ from normals who show an increase in carpal angle with age.     

Reliability of anthropometric methods and replicate measurements

The Spearman-Brown Prophesy formula, derived from psychometrics, may be used in anthropometric studies to describe the relationship between the intraclass reliability coefficient for a single measurement and the reliability resulting from the mean of replicate measurements. This theory may be applied to determine expected reliabilities of anthropometric protocols using replicate measurements and to determine the numbers of replicate measurements necessary to achieve desired levels of reliability.     

Usefulness of R-R interval and its variability in evaluation of thermal comfort

The use of R-R interval and the coefficient of variation in R-R intervals (CV_R-R) for the evaluation of thermal comfort was investigated. The experiments were carried out with ten male subjects but data from one were excluded from the analysis. Thermal sensation, comfort, and tolerance of environmental conditions were reported and mean skin temperature, R-R interval and CV_R-R were monitored during a 3 h period in a climatic chamber with the operative temperature set at 26, 20, or 30° C. Relative humidity was maintained at ca. 50% in each case. At the operative temperature of 20° C, the mean skin temperature was significantly lower, the cold sensation was significantly more intense, and discomfort was significantly greater than at 26° C and R-R interval was increased significantly. Seven of the nine subjects were unable to tolerate this thermal environment. The R-R interval and CV_R-R were increased in five and four of those seven subjects, respectively. At the operative temperature of 30° C, the mean skin temperature was significantly higher, and the sensation of warmth was significantly more intense than at 26° C. Seven of the nine subjects felt discomfort, and four of the seven reported an inability to tolerate this thermal environment. The R-R interval and CV_R-R were decreased in four and three of these four subjects, respectively. At the operative temperature of 20° C CV_R-R was significantly greater than that at 30° C. Together with the subjective indices, R-R interval and CV_R-R are considered worthy of further evaluation as objective indications of the effect on people of the thermal environment.     

Age-dependent heart rate variability in preschool children living under the conditions of the European Arctic region

The results of analysis of specific characteristics of the heart rate variability (HRV) regulation in preschool children living under the Arctic high-latitude conditions are presented. The principal ageand gender-specific differences in the HRV regulation have been inferred from the intergroup evaluations of the HRV indicators in boys and girls. A functional developmental delay has been shown in 2.5-year-old girls compared with boys of the same age group. The applied orthostatic test has shown lower reserve capacities in children of the senior group compared with the junior group. It has been shown that the mechanisms of the regulation of cardiac rhythm in girls experience higher strain during orthostasis as compared with boys. The division of children into age groups with an age difference of one year has allowed the detection of the tendency towards basically different responses to functional loads during orthostasis. The mean HRV values characteristic of four- to six-year-old children living in the Arctic are presented. It has been shown that the children living at middle latitudes have a higher adaptive potential compared with the children living in high-latitude Arctic areas.     

Anthropometric evaluation of dysmorphology in craniofacial anomalies: Treacher Collins syndrome

Advances in surgical techniques for correction of craniofacial anomalies have necessitated the development of objective pre- and postoperative quantitative assessments. Standard anthropometric techniques, supplemented by additional methods oriented to specific clinical problems, have proved useful in defining surface dysmorphology in craniofacial patients. A series of 77 surface measurements of the head and face and 41 proportions were determined in 20 preoperative patients with Treacher Collins syndrome, a rare congenital defect of the first and second branchial arches. To permit comparison with age- and sex-specific data for healthy North American children, the patient data were converted to standard (Z) scores. To test the hypothesis Z = 0, Student's t-test was performed on all variables. The anthropometric findings verified many of the clinical findings in this syndrome. In addition, a number of previously unreported defects were found. The cranium was low and short with a low, narrow forehead and a narrow cranial base. The face was narrow and shallow, the mandible long and narrow, and the lower face receding. The eye fissures were short with an antimongoloid inclination, but the orbits were hyperteloric. The nasal root was high and wide, the nasofrontal angle open, and the bridge inclination low. The labial fissure was narrow, and the ears were microtic. Except in the nasal root the defects were hypoplastic. Most of these defects were either horizontal or anteroposterior. Recognition of the defective areas and their contribution to disproportions of the head and face is important in the development of surgical strategies.     

The evolutionary history of Drosophila buzzatii. XXXV. Inversion polymorphism and nucleotide variability in different regions of the second chromosome

Inversions are portions of a chromosome where the gene order is reversed relative to a standard reference orientation. Because of reduced levels of recombination in heterokaryotypes, inversions have a potentially important effect on patterns of nucleotide variability in those genomic regions close to, or included in, the inverted fragments. Here we report sequence variation at three anonymous regions (STSs) located at different positions in relation to second-chromosome inversion breakpoints in 29 isochromosomal lines derived from an Argentinean population of Drosophila buzzatii. In agreement with previous findings in Drosophila, gene flux (crossing over and/or gene conversion) between arrangements seems to appreciably increase as we approach the middle sections of inversion 2j, and patterns of nucleotide variability within, as well as genetic differentiation between chromosome arrangements, are comparable to those observed at the molecular marker outside the inverted fragments. On the other hand, nucleotide diversity near the proximal breakpoint of inversion 2j is reduced when contrasted with that found at the other regions, particularly in the case of derived inverted chromosomes. Using the data from the breakpoint, we estimate that the inversion polymorphism is approximately 1.63 N generations old, where N is the effective population size. An excess of low-frequency segregating polymorphisms is detected; mostly in the ancestral 2st arrangement and probably indicating a population expansion that predates the coalescent time of inversion 2j. Heterogeneity in mutation rates between the markers linked to the inversions may be sufficient to explain the different levels of nucleotide diversity observed. When considered in the context of other studies on patterns of variation relative to physical distance to inversion breakpoints, our data appear to be consistent with the conclusion that inversions are unlikely to be "long-lived" balanced polymorphisms.     

Arm lengths and arm reaches: some interrelationships of structural and functional body dimensions

Structural measurements of the human body have for the most part been of little practical use as indicators of such functional body dimensions as arm reaches. These dimensions, which define the area around the body to which a person can reach given certain specified conditions and constraints are often critical for the design and layout of workspaces. However, they are relatively difficult and time-consuming to obtain, usually requiring specially constructed measuring systems for each differing design situation, as well as resurveys for each physically distinct population. An alternate approach, described here, investigates the interrelationships between these two classes of measurements with the aim of predicting functional reaches from structural body dimensions. In the present study traditional structural measurements and 117 functional arm reaches were obtained on 100 subjects. Correlations between the two types of measures are reported. Regression equations are presented which can predict functional arm reaches from two structural body dimensions on anthropometrically differing populations under a fixed set of workspace conditions.     

Age-associated differences in motor output variability and coordination during the simultaneous dorsiflexion of both feet

Older adults are more variable than young adults on tasks that demand the simultaneous control of more than one effector, and the difference between age groups may be related to their different capacity of coordinating the force output of the involved effectors. The goal of this study was to determine whether age-associated differences in motor output variability during tasks involving the simultaneous dorsiflexion of two feet can be partially explained by differences in coordination and possibly attenuated by physical training. Ten young and 22 old adults (10 trained and 12 untrained old adults) volunteered to participate in the study. Trained older adults had experience in a high-intensity mixed modality training (MMT) regime for a minimum of 1?year. Volunteers performed successive trials of a constant force task and a goal-directed task, with and without visual feedback. Within- and between-trial variability were calculated and coordination was quantified using the uncontrolled manifold (UCM) approach (i.e., co-variation of the force outputs of both feet were used to quantify a motor synergy index). Older adults exhibited greater variability and lower synergy (p?p?相似文献   

大鼠心率变异性频谱中高频成分的中枢机理分析

本文探讨心率变异性（ＨＲＶ）频谱中高频成分的中枢机理。对正常ＳＤ大量给予不同频率的人工通气并电刺激延髓疑核,观察ＨＲＶ频谱的改变,记录与呼吸节律同步的延髓头端腹外侧区（ｒＶＬＭ）及其周围区神经元细胞外单位放电,对ＨＲＶ和放电变异性进行相干函数分析。结果显示：（１）ＨＲＶ的高频成分的中心频率随着人工通气频率的增加而增加,呈高度线性相关,（ｒ＝０．８３,Ｐ〈０．０００１）;（２）对ｒＶＬＭ及其周围区与     

Occurrence and variability of River Habitat Survey features across Europe and the consequences for data collection and evaluation

River Habitat Survey (RHS) data collected for the EU-funded STAR project was used to identify hydromorphological characteristic features of rivers in four European regions namely: lowlands; mountain; the Alps; and the Mediterranean. Using RHS attributes, Habitat Quality Assessment (HQA) – a measure of natural habitat diversity, and Habitat Modification Score (HMS) – a measure of anthropogenic modification, we identified considerable differences in frequency, diversity and evenness of features between the regions. A relatively small subset of features clearly distinguish the hydromorphological characters of lowland, Alpine and southern European rivers. It was more difficult to distinguish mountain rivers from Alpine rivers. The highest statistical differences are observed between Lowland and Mountain region. Within the four regions studied the RHS attributes that most strongly influence the HQA and HMS indices were identified. We conclude that specific effort should be made to ensure these are recorded properly as part of the quality control of RHS data. Electronic supplementary material Electronic supplementary material is available for this article at and accessible for authorised users.     

The variability of nitrifying activity in field soils

The effect of pH on the activity of nitrifying organisms was examined in pasture soils ranging in pH from 4.9 to 7.3, using a short-term nitrification assay (SNA). The optimum pH for nitrifier activity (pH_opt) was generally close to the soil pH, suggesting that the indigenous nitrifier populations adjusted to the prevailing soil pH. A consequence was that the SNA at the soil pH (SNA_pH) bore a near 1:1 relationship with the SNA at the pH_opt (SNA_opt) over a wide range of SNA values. The effect of soil moisture tension on the SNA was less pronounced than that of pH, but an optimum occurred around pF 3.4.     

Genetic variability at the pig SLA complex in U.S. breeds of pigs1

Lymphocytes from 90 mature pigs and 548 growing pigs from 6.5 litters were screened with cytotoxic antibodies against swine lymphocyte antigens. Pigs included in the survey were from the Chester White, Duroc, Hampshire, Landrace and Yorkshire breeds. Significant differences between breeds were found in the frequency of the three haplotypes tested. Such differences may provide the genetic variability needed to determine associations between disease susceptibility and the pig's major histocompatibility gene complex.     

Germination variability and the effect of various pre-treatment on germination in the perennial spurge Euphorbia nicaeensis All.

Patterns of seed germination of the perennial spurge Euphorbia nicaeensis were studied in three populations in south-western Spain. We investigated the variation in seed viability and germination among individuals, and among populations over 2 consecutive years. We also studied if diverse factors such as temperature, acid scarification, darkness or caruncle loss affect the germination of the seeds.

Interindividual and interpopulation variability in seed viability was found. E. nicaeensis seeds are nondormant, so differences in interpopulation viability translate into differences in final germination rates. The germination percentage of the seeds from each population was similar in the 2 years studied. The effects of diverse factors were homogeneous in the two populations studied. Darkness has no effect on seed germination, and ecarunculate seeds germinated in the same proportions as carunculate seeds; this could allow the seeds to germinate in the chambers of deserted anthills. Acid scarification significantly reduced the germination percentage in only one of the populations, but over 50% of the seeds germinated, which could allow herbivores to act as occasional dispersing agents. The seeds that were preheated at 100 °C for 1 and 5 min germinated in the same proportions as the control group. The seeds that were preheated at 120 °C for 5 min displayed a significant decrease in germination, but the percentage was over 40% for both populations, indicating that the seeds could still germinate after the passage of a fire.     

Diarrheal diseases and growth retardation in preschool Guatemalan children.

The relationship between diarrheal diseases and growth increments in total body length and weight was investigated in 716 rural Ladino Gautemalan children. Data on diarrheal diseases were provided by the mothers through retrospective surveys carried out at 14-day intervals. Increments in length and weight, semestral from near birth at four years and yearly thence to seven, were related to days ill with diarrheal diseases during the same time interval. Because the data here reported were collected over a two year period, a child may have had information for more than one period. In total, 1,343 child periods were investigated. Days ill with diarrheal diseases were found to be significantly associated with reduced growth in length and weight. It was assumed that the average differences in growth by seven years of age between children in the present sample and children from well-to-do societies, are mainly a function of environmental differences and consequently, a measure of the extent of growth retardation. By expressing the growth retardation specifically associated with diarrheal diseases as a fraction of the above differences it was then estimated that around 10% of this growth retardation was associated with diarrheal diseases.     

On the relation between genetic and environmental variability in animals

Summary If a phenotypic character is under stabilizing selection, the selective disadvantage of a nonoptimal genotype will decrease exponentially to zero as the proportion of phenotypic variation that is environmental in origin -V _e /V _p - increases. Under the modified mutation-drift hypothesis of genetic polymorphism, the proportion of mutations that are effectively neutral and average heterozygosity should increase with this ratio. Invertebrates, because of their small size, fast development, and low degree of homeostasis (relative to vertebrates), are expected to show a larger environmental component of phenotypic variation than vertebrates. This may help explain why invertebrates are in general more genetically variable than vertebrates and why, when laboratory populations ofDrosophila are maintained in heterogeneous environments, genetic variability is lost less rapidly than when they are kept in constant conditions.