Different Correlations (different + correlation)

Distribution by Scientific Domains

Selected Abstracts

Sperm morphology and aneuploidies: defects of supposed genetic origin

ANDROLOGIA, Issue 6 2006
G. Collodel
Summary As individuals with genetic sperm defects are intracytoplasmic sperm injection candidates, the study of the chromosomal constitution of their spermatozoa is of great interest. This study is a review of the current literature concerning fluorescence in situ hybridisation studies in spermatozoa with genetic sperm defect as ,round head', ,dysplasia of fibrous sheath' (DFS), ,primary ciliary dyskinesia' (PCD), the ,detached tail' and the ,absence of fibrous sheath'. Regarding sperm head defects, elevated XY disomy and diplodies were detected. Genetic defects affecting the sperm tail seemed to have a different correlation with chromosome meiotic segregation. Only chromosome 18, among the autosomes, was studied and the percentage of frequency of disomy was generally within the normal range. In the more frequently studied defect, DFS, the alterations in gonosome disomy and diploidy were recorded by different groups. Regarding PCD defects, elevated frequencies of disomy of sex chromosomes and diploidy were observed, whereas the absence of the fibrous sheath and the detached tail did not show any meiotic disturbance. The problem of genetic sperm defects should be seriously considered when these sperm are used for assisted reproduction, owing to the high risk of transmission of chromosomal imbalance and of mutations that could cause genetic sperm defects in offspring. [source]

Inherent flammability parameters,Room corner test application

J. G. Quintiere
Abstract It has been hypothesized that four parameters are solely responsible for a material's performance in a flammability scenario. This excludes effects of material physical integrity, i.e. melting, delamination, etc. They are (1) the critical heat flux below which piloted ignition cannot occur (CHF), (2) the ratio of heat of combustion to heat of gasification (HRP), (3) the thermal response parameter related to the thermal inertia and the ignition temperature (TRP), and (4) the available energy per unit area (AEP). The fire scenario controls the process by its initial heat flux and region of ignition. The hypothesis is applied to 54 tests of the ISO Room Corner Test to assess its validity. It is shown that these four parameters give good correlations in predicting the time to flashover and whether it occurs. In principle, different correlations could be developed for other scenarios of tests and fire configurations. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Aboveground biomass estimation of the shrubs, Echiochilon fruticosum (Desf.) and Helianthemum kahiricum (Del.) in the arid zone rangelands of Tunisia

Abdelkader Idi
Abstract The knowledge of the plant biomass is very important for the assessment of the rangeland productivity. It could help to select the appropriate species for the improvement of natural ecosystems (rehabilitation, restoration and seedling). By examining different correlations between the biomass production and the volume parameters of two North African shrub species of high range value (Echiochilon fruticosum Desf. and Helianthemum kahiricum Del.), we aimed to establish the appropriate regression models, which could be useful for the prediction of the productivity of these species. The data showed a significant relationship between the total biomass (TB) production and the mean diameter (MD) of the studied species (R2 = 0.65 for Echiochilon and R2 = 0.75 for Helianthemum). Likewise, annual fresh production (leaves and current-year shoots) was well correlated with MD of Helianthemum (R2 = 0.82). However, the correlation between these two parameters was relatively low for Echiochilon (R2 = 0.42). Résumé Il est très important de connaître la biomasse végétale pour évaluer la productivité d'un territoire. Il peut être utile de sélectionner les espèces appropriées pour l'amélioration d'écosystèmes naturels (restauration, réhabilitation, plantations). En analysant différentes corrélations entre les paramètres de production de biomasse et de volume de deux espèces d'arbustes nord-africains de grande distribution (Echiochilon fruticosum Desf. et Helianthemum kahiricum Del.), nous avons voulu établir les modèles de régression appropriés qui pourraient servir pour prédire la productivité de ces espèces. Les données ont montré un lien significatif entre la production totale de biomasse et le diamètre moyen des espèces étudiées (R2 = 0.65 pour Echiochilon, et R2 = 0.75 pour Helianthemum). De même, la production annuelle de matière fraîche (feuilles et rameaux de l'année) était bien liée au diamètre moyen pour Helianthemum (R2 = 0.82). Cependant, la corrélation entre ces deux paramètres était relativement faible pour Echiochilon (R2 = 0.42). [source]

Effects of shear and electrical properties on flow characteristics of pharmaceutical blends

AICHE JOURNAL, Issue 3 2010
Kalyana C. Pingali
Abstract This article examines the effects and interactions of shear rate, shear strain on electrical and flow properties of pharmaceutical blends. An unexpectedly strong relation between the flow and passive electrical properties of powders is observed to depend on the shear history of the powder bed. Charge density, impedance, dielectrophoresis, flow index, and dilation were measured for several pharmaceutical blends after they were subjected to a controlled shear environment. It was found that the increase in the shear strain intensified the electrical properties for blends that did not contain MgSt. The opposite effect was found in blends lubricated with MgSt. Different shear conditions resulted in different correlations between flow index and dilation. Flow properties of powders were found to improve with continuous exposure to shear strain. It was also found that flow properties correlated to charge acquisition and impedance for different shear treatments. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source]

Seasonal influenza activity in Hong Kong and its association with meteorological variations

Paul K.S. Chan
Abstract Influenza seasons appear consistently in the temperate regions, but are more variable in tropical/subtropical regions. The determinant for such variation remains poorly understood. This study documented the activity of influenza over a 10-year period in Hong Kong; examining its association with changes in temperature and relative humidity. The two types of influenza exhibited different correlations with meteorological variations. Influenza A showed two seasonal peaks occurring respectively in winter/spring and summer months in most years. Influenza B showed a clear winter/spring peak, but its activity during summer months was more variable. Cold and humid conditions were associated with a higher activity of both influenza A and B. In contrast, hot and humid conditions were associated with a higher activity of influenza A, but were associated with only a moderate, less consistent increase in the activity of influenza B. A trend of increase in the magnitude of summer peaks of influenza A, but not influenza B, was observed. A hypothetical 2°C rise in temperature would decrease the proportion of favorable days for influenza A in December,April from 78% to 57%, but an increase from 58% to 71% in May,November; with a similar effect (from 83% to 62%) for influenza B during December,April, but a modest change (from 17% to 18%) during May,November. The presence of two seasonal peaks of influenza annually emphasizes the need to evaluate the duration of protective immunity offered by vaccination. Further study on the effects of climate change and global warming on the activity of influenza is warranted. J. Med. Virol. 81:1797,1806, 2009. © 2009 Wiley-Liss, Inc. [source]

Relationships between plasma leptin levels and body composition parameters measured by different methods in postmenopausal women

Toivo Jürimäe
The aim of this study was to determine the effects of body composition measured by different methods with different measurement errors on fasting plasma leptin level in normal body mass and obese postmenopausal women. It was hypothesized that the relationship between plasma leptin concentration and body fat is higher using more sophisticated laboratory methods (dual energy X-ray absorptiometry, DXA) in comparison with field methods (bioelectrical impedance analysis, BIA, or skinfold thickness) for body fat measurement because of the greater precision of DXA measurements. Thirty-five postmenopausal (55,83 years of age) healthy Estonian women were divided into two groups: BMI < 27kg/m2 as non obese (n = 18) and BMI> 27kg/m2 as obese (n = 17). Body composition was determined using DXA (total body, arms, legs, and trunk fat percent, fat mass, and LBM) and BIA methods. Body fat percent was significantly higher using the DXA method. Subcutaneous adipose tissue distribution was determined by measuring nine skinfold thicknesses. Body fat distribution was defined as the ratio of waist-to-hip (WHR) and waist-to-thigh (WTR) circumferences. Leptin was determined by means of radioimmunoassays. Leptin concentration was not significantly different between groups (19.0 ± 13.3 and 21.5 ± 21.5ng/ml in non obese and obese groups, respectively). Body fat percent and fat weight measured by DXA or BIA methods and all measured skinfold thickness values, except biceps and abdominal, were higher in obese women. Body height did not correlate significantly with leptin concentrations. The relationships between leptin concentration were highest with body weight (r = 0.67) and BMI (r = 0.73) values in the obese group. All measured body fat parameters using DXA or BIA methods correlated significantly with plasma leptin concentration in the obese group. LBM did not influence the leptin concentration in postmenopausal women. Stepwise multiple regression analysis indicated that the body fat percent measured using the DXA method was highly related to plasma leptin concentration in the obese group (63.2%; R2 × 100). When absolute fat mass parameters were considered, leptin concentration was related to the mass of arms fat tissue in the obese group of women (62.3%). Body fat percent measured by BIA was highly related to plasma leptin concentration in the obese group (63.3%). Only biceps skinfold thickness was related to leptin concentration (22.5% and 58.9%, in the nonobese and obese groups, respectively) from the nine measured skinfold thicknesses. WHR and WTR did not reflect leptin concentration in different groups of postmenopausal women. It was concluded that different methods of body composition estimation generate different correlations with plasma leptin concentration. Body fat percent and especially fat mass measured by DXA are the main predictors relating to plasma leptin concentration in obese, but not in nonobese, postmenopausal women. In addition, fat mass in arms measured by DXA and biceps skinfold thickness were also highly related to leptin concentration. Am. J. Hum. Biol. 15:628,636, 2003. © 2003 Wiley-Liss, Inc. [source]

Fluid flow in an impacting symmetrical tee junction III: three-phase air/water/oil flow

A. P. Doherty
Abstract Results are presented on three-phase air/oil/water horizontal flow in a 0.026 m i.d. symmetrical impacting tee junction. The flow regimes observed agreed with an existing three-phase flow map. The inversion from water-dominated (WD) to oil-dominated (OD) flow was at an oil-to-liquid volumetric ratio of fo = 0.285. The inversion was at a low fo value because of the relatively tranquil conditions studied. Retention of oil on the pipe wall at the air/water two-phase condition at fo = 0 resulted in a dramatic increase in the pressure drop above that expected for the two-phase flow. The pressure drop in the tee junction arms increased with liquid-flow rate. The actual tee junction pressure drop showed a similar pattern to that observed in the inlet arm. The pressure drop was relatively constant in the OD region but showed a dramatic increase in the WD and inversion regions at low fo values. Non-dimensionalising the junction pressure drop as le/d gave a similar pattern but the scatter of data increased. The tee pressure loss data were modelled using the Lockhart-Martinelli ,G parameter and gave similar but different correlations for the WD and OD regions. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source]