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Curvilinear Relationships (curvilinear + relationships)
Selected AbstractsThree-dimensional sonographic volume measurement of the fetal spleenJOURNAL OF OBSTETRICS AND GYNAECOLOGY RESEARCH (ELECTRONIC), Issue 5 2007Toshiyuki Hata Abstract Aim:, The objective of this longitudinal study was to evaluate the growth of the fetal spleen in normal pregnancies, using three-dimensional ultrasound. Methods:, Three-dimensional sonographic examinations were performed on 14 appropriate-for-gestational-age fetuses. Fetal splenic volume was measured every 2,3 weeks after 20 weeks of gestational age until delivery. Results:, Curvilinear relationships were found between the gestational age and splenic volume (R2 = 80.2%, P < 0.0001), and normal ranges of splenic volume measurements for estimating the growth of the fetal spleen during normal pregnancy were generated. We found that the splenic volume calculation based on the equation for the volume of the ellipsoid by conventional two-dimensional ultrasound in previous investigations is about twice as large as that using three-dimensional ultrasound in our study, whereas the present data described in this study is quite comparable with previous data from an autopsy series. Conclusion:, Our findings suggest that the standard curve for the fetal splenic volume using three-dimensional ultrasound provides a superior means for evaluating the normal splenic growth in the fetus and for identifying splenic abnormalities in utero. However, the data and its interpretation in our study should be taken with some degree of caution because of the small number of subjects studied. Further studies involving a larger sample size would be needed to confirm these findings. [source] Dispersal in drift-prone macroinvertebrates: a case for density-independenceFRESHWATER BIOLOGY, Issue 5 2002S. HUMPHRIES 1.,Studies of dispersal of macroinvertebrates in streams and rivers tend to be focused on drift, whilst benthic movements are usually considered to be less important. 2.,Field-enclosure experiments with the mayfly Baetis rhodani indicate that net dispersal in this species is simply a proportional loss of individuals from the benthos. 3.,Neither net upstream or downstream movements exhibited evidence of density-dependence in the form of curvilinear relationships between initial and final densities. 4.,The net number of animals moving upstream did not differ significantly from the net number moving downstream. 5.,The probable mechanisms behind density-independent dispersal are discussed, as are the implications for our understanding of population dynamics in relation to invertebrate drift. [source] Long work hours: a social identity perspective on meta-analysis dataJOURNAL OF ORGANIZATIONAL BEHAVIOR, Issue 7 2008Thomas W. H. Ng The current study utilizes social identity theory to investigate employees' work hours. Specifically, we use meta-analysis to examine the relationships between hours worked and indicators of organizational identity (e.g., organizational support and tenure), occupational identity (e.g., human capital investments and work centrality), and family identity (e.g., family responsibilities and family satisfaction). The meta-analysis also allowed us to explore other important correlates of hours worked (e.g., situational demands, job performance, mental health, and physical health), moderating variables (e.g., age, gender, and job complexity), and curvilinear relationships of work hours to social identity indicators. Overall, we found that occupational factors and situational demands had the strongest relationships with hours worked, hours worked were negatively associated with measures of employee well-being, gender had several significant moderating effects, and there were curvilinear relationships between hours worked and well-being and work,family conflict variables. The article concludes with directions for future theoretical and empirical research. Copyright © 2008 John Wiley & Sons, Ltd. [source] Remote sensing of protected areas to derive baseline vegetation functioning characteristicsJOURNAL OF VEGETATION SCIENCE, Issue 5 2004Martín F. Garbulsky Abstract: Question: How can we derive baseline/reference situations to evaluate the impact of global change on terrestrial ecosystem functioning? Location: Main biomes (steppes to rain forests) of Argentina. Methods: We used AVHRR/NOAA satellite data to characterize vegetation functioning. We used the seasonal dynamics of the Normalized Difference Vegetation Index (NDVI), a linear estimator of the fraction of the photosynthetic active radiation intercepted by vegetation (fPAR), and the surface temperature (Ts), for the period 1981,1993. We extracted the following indices: NDVI integral (NDVI -I), NDVI relative range (Rrel), NDVI maximum value (Vmax), date of maximum NDVI (Dmax) and actual evapotranspiration. Results: fPAR varied from 2 to 80%, in relation to changes in net primary production (NPP) from 83 to 1700 g.m- 2.yr -1. NDVI -I, Vmax and fPAR had positive, curvilinear relationships to mean annual precipitation (MAP), NPP was linearly related to MAP. Tropical and subtropical biomes had a significantly lower seasonality (Rrel) than temperate ones. Dmax was not correlated with the defined environmental gradients. Evapotranspiration ranged from 100 to 1100 mm.yr -1. Interannual variability of NDVI attributes varied across the temperature and precipitation gradients. Conclusions: Our results may be used to represent baseline conditions in evaluating the impact of land use changes across environmental gradients. The relationships between functional attributes and environmental variables provide a way to extrapolate ecological patterns from protected areas across modified habitats and to generate maps of ecosystem functioning. [source] Taller women do better in a stressed environment: Height and reproductive success in rural Guatemalan womenAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 3 2008Thomas V. Pollet Previous research on the relationship between height and reproductive success in women has produced mixed results. One possible explanation for these is mediation by ecological factors, such as environmental stress. Here we investigate female height and reproductive success under conditions of environmental stress (poverty) using a large scale dataset from Guatemala (n = 2,571). Controlling for educational attainment, age and ethnicity, we examined relationships between height and childlessness, occurrence of a stillbirth, fertility and child survival. There was no significant relationship between height and never haven given birth. Extremely short women had a significantly raised likelihood of experiencing stillbirth. There were curvilinear relationships between height and age at first birth, fertility, and survival rates for children. Overall, though, the penalties for short stature, particularly in terms of child survival, were far greater than those associated with extreme tallness, and so female height is positively associated with overall fitness in this population. Am. J. Hum. Biol., 2008. © 2008 Wiley-Liss, Inc. [source] | ||||||||||