Structural Variables (structural + variable)

Distribution by Scientific Domains


Selected Abstracts


The influence of family environment and child temperament on work/family role strain for mothers and fathers

INFANT AND CHILD DEVELOPMENT, Issue 5 2003
Marceline Lee
Abstract This study examined the additive effect of structural variables, child characteristics, and the family environment on mothers' and fathers' work/family role strain. Differences between mothers and fathers on these variables were also examined. The sample consisted of 36 dualearner families whose children had been in daycare from infancy through 4 years of age. Structural variables included work schedules and time spent with child for mothers only, fathers only, and both parents together with child. Child characteristics included temperament and health. Family environment variables included different components of the family environment (conflict, cohesion, expressiveness, organization, and control) and parenting daily hassles. Results showed that mothers' time with child and caregiving for child were greater than fathers'. Mothers reported more expressiveness in the family and more daily hassles with children than fathers. Mothers' level of role strain was also significantly higher than fathers'. For mothers, role strain was associated with hours away from home, child sociability, family conflict, and daily hassles resulting in an R2 of 0.57. Fathers' role strain was associated with family expressiveness, organization, and their wives' daily hassles resulting in an R2 of 0.37. Data suggest that mothers' and fathers' role strain may be driven by somewhat different factors. For women, aspects of the family and the child and work hours accounted for a considerable portion of the variance while for men, only aspects of the family environment were associated with their level of role strain. Copyright 2003 John Wiley & Sons, Ltd. [source]


Nonheterochronic developmental changes underlie morphological heterochrony in the evolution of the Ardeidae

JOURNAL OF EVOLUTIONARY BIOLOGY, Issue 2 2000
Cubo
Evolutionary changes in developmental timing and rates (heterochrony) are a source of morphological variation. Here we explore a central issue in heterochronic analysis: are the alterations in developmental timing and rates the only factor underlying morphological heterochrony? Tarsometatarsal growth through endochondral ossification in Ardeidae evolution has been taken as a case study. Evolutionary changes in bone growth rate (morphological heterochrony) might be either (a) the result of alterations in the mitotic frequency of epiphyseal chondrocytes (process-heterochrony hypothesis), or (b) the outcome of alterations in the number of proliferating cells or in the size of hypertrophic chondrocytes (structural hypothesis). No correlation was found between tarsometatarsal growth rates and the frequency of cell division. However, bone growth rates were significantly correlated with the number of proliferating cells. These results support the structural hypothesis: morphological acceleration and deceleration are the outcome of evolutionary changes in one structural variable, the number of proliferating cells. [source]


GENDER, STRUCTURAL DISADVANTAGE, AND URBAN CRIME: DO MACROSOCIAL VARIABLES ALSO EXPLAIN FEMALE OFFENDING RATES?,

CRIMINOLOGY, Issue 2 2000
DARRELL STEFFENSMEIER
Building on prior macrosocial-crime research that sought to explain either total crime rates or male rates, this study links female offending rates to structural characteristics of U.S. cities. Specifically, we go beyond previous research by: (1) gender disaggregating the Uniform Crime Report (UCR) index-crime rates (homicide, robbery, aggravated assault, burglary, larceny-theft) across U.S. cities; (2) focusing explicitly on the effects of structural disadvantage variables on the index-offending rates of females; and (3) comparing the effects of the structural variables on female rates with those for male rates. Alternative measures of structural disadvantage are used to provide more theoretically appropriate indicators, such as gender-specific poverty and joblessness, and controls are included for age structure and structural variables related to offending. The main finding is consistent and powerful: The structural sources of high levels of female offending resemble closely those influencing male offending, but the effects tend to be stronger on male offending rates. [source]


Crystal structure refinement of the ternary compound Cu2SnTe3 by X-ray powder diffraction

CRYSTAL RESEARCH AND TECHNOLOGY, Issue 4 2008
G. E. Delgado
Abstract The ternary compound Cu2SnTe3 crystallizes in the Imm2 (N 44) space group, Z = 2, with a = 12.833(4) , b = 4.274(1) , c = 6.043(1) , V = 331.5(1) 3. Its structure was refined from X-ray powder diffraction data using the Rietveld method. The refinement of 25 instrumental and structural variables led to Rp = 10.2%, Rwp = 11.8%, Rexp = 7.7%, RB = 10.6%, S = 1.6 and ,2 = 2.6, for 5501 step intensities and 163 independent reflections. This compound is isostructural with Cu2GeSe3, and consists of a three-dimensional arrangement of slightly distorted CuTe4 and SnTe4 tetrahedra connected by common corners. ( 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


The influence of family environment and child temperament on work/family role strain for mothers and fathers

INFANT AND CHILD DEVELOPMENT, Issue 5 2003
Marceline Lee
Abstract This study examined the additive effect of structural variables, child characteristics, and the family environment on mothers' and fathers' work/family role strain. Differences between mothers and fathers on these variables were also examined. The sample consisted of 36 dualearner families whose children had been in daycare from infancy through 4 years of age. Structural variables included work schedules and time spent with child for mothers only, fathers only, and both parents together with child. Child characteristics included temperament and health. Family environment variables included different components of the family environment (conflict, cohesion, expressiveness, organization, and control) and parenting daily hassles. Results showed that mothers' time with child and caregiving for child were greater than fathers'. Mothers reported more expressiveness in the family and more daily hassles with children than fathers. Mothers' level of role strain was also significantly higher than fathers'. For mothers, role strain was associated with hours away from home, child sociability, family conflict, and daily hassles resulting in an R2 of 0.57. Fathers' role strain was associated with family expressiveness, organization, and their wives' daily hassles resulting in an R2 of 0.37. Data suggest that mothers' and fathers' role strain may be driven by somewhat different factors. For women, aspects of the family and the child and work hours accounted for a considerable portion of the variance while for men, only aspects of the family environment were associated with their level of role strain. Copyright 2003 John Wiley & Sons, Ltd. [source]


On the equivalence of the Rietveld method and the correlated integrated intensities method in powder diffraction

JOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 4 2004
William I. F. David
The Rietveld method is the most straightforward and statistically correct approach for the refinement of crystal structure parameters from powder diffraction data. The equivalent two-stage approach, involving the refinement of structural parameters based on integrated intensities extracted using the Pawley method, is extremely useful in circumstances such as the global optimization methods of structure determination, where a great many refinements need to be performed very quickly. The equivalence is emphasized in a simple mathematical relationship between the goodness of fits obtained in Rietveld, Pawley and correlated integrated intensities refinements. A rationale is given for determining the estimated standard deviations for structural variables from powder diffraction data. [source]


Explaining bird species composition and richness in eucalypt-dominated remnants in subhumid Tasmania

JOURNAL OF BIOGEOGRAPHY, Issue 9 2003
Michael A. MacDonald
Abstract Aim To determine the factors influencing the distribution of birds in remnants in a fragmented agricultural landscape. Location Forty-seven eucalypt remnants and six sites in continuous forest in the subhumid Midlands region of Tasmania, Australia. Methods Sites were censused over a two-year period, and environmental data were collected for remnants. The avifauna of the sites was classified and ordinated. The abundances of bird species, and bird species composition, richness, abundance and diversity were related to environmental variables, using simple correlation and modelling. Results There were two distinct groups of sample sites, which sharply differed in species composition, richness, diversity and bird abundance, separated on the presence/absence of noisy miner (Manorina melanocephala Latham) colonies, remnant size, vegetation structural attributes and variables that reflected disturbance history. The approximate remnant size threshold for the change from one group to another was 20,30 ha. Remnant species richness and diversity were most strongly explained by remnant area and noisy miner abundance, with contributions from structural and isolation attributes in the second case. Segment richness was explained by precipitation, logging history and noisy miner abundance. Bird abundance was positively related to precipitation and negatively related to tree dieback. The 28 individual bird species models were highly individualistic, with vegetation structural variables, noisy miner abundance, climatic variables, variables related to isolation, area, variables related to floristics, disturbance variables, the nature of the matrix and remnant shape all being components in declining order of incidence. Age of the remnant did not relate to any of the dependent variables. Main conclusions Degraded and small remnants may have become more distinct in their avifaunal characteristics than might otherwise be the case, as a result of the establishment of colonies of an aggressive native bird, the noisy miner. The area, isolation and shape of remnants directly relate to the abundance of relatively few species, compared to vegetation attributes, climate and the abundance of the noisy miner. The nature of the matrix is important in the response of some species to fragmentation. [source]


Monitoring Teriparatide-Associated Changes in Vertebral Microstructure by High-Resolution CT In Vivo: Results From the EUROFORS Study,

JOURNAL OF BONE AND MINERAL RESEARCH, Issue 9 2007
Christian Graeff Dipl-Ing
Abstract We introduce a method for microstructural analysis of vertebral trabecular bone in vivo based on HRCT. When applied to monitor teriparatide treatment, changes in structural variables exceeded and were partially independent of changes in volumetric BMD. Introduction: Monitoring of osteoporosis therapy based solely on bone densitometry is insufficient to assess anti-fracture efficacy. Assessing bone microstructure in vivo is therefore of importance. We studied whether it is possible to monitor effects of teriparatide on vertebral trabecular microstructure independent of BMD by high-resolution CT (HRCT). Materials and Methods: In a subset of 65 postmenopausal women with established osteoporosis who participated in the EUROFORS study, HRCT scans of T12, quantitative CT of L1,L3, and DXA of L1,L4 were performed after 0, 6, and 12 mo of teriparatide treatment (20 ,g/d). We compared BMD and 3D microstructural variables in three groups of women, based on prior antiresorptive treatment: treatment-nave; pretreated; and pretreated women showing inadequate response to treatment. Results: We found statistically highly significant increases in most microstructural variables and BMD 6 mo after starting teriparatide. After 12 mo, apparent bone volume fraction (app. BV/TV) increased by 30.6 4.4% (SE), and apparent trabecular number (app. Tb.N.) increased by 19.0 3.2% compared with 6.4 0.7% for areal and 19.3 2.6% for volumetric BMD. The structural changes were partially independent of BMD as shown by a significantly larger standardized increase and a standardized long-term precision at least as good as DXA. Patients who had shown inadequate response to prior osteoporosis treatment did show improvements in BMD and structural measures comparable to treatment-nave patients. Conclusions: HRCT is a feasible method for longitudinal microstructural analysis of human vertebrae in vivo, offers information beyond BMD, and is sufficiently precise to show profound effects of teriparatide after 12 mo. [source]


Genome Screen for Quantitative Trait Loci Underlying Normal Variation in Femoral Structure

JOURNAL OF BONE AND MINERAL RESEARCH, Issue 6 2001
Daniel L. Koller
Abstract Femoral structure contributes to bone strength at the proximal femur and predicts hip fracture risk independently of bone mass. Quantitative components of femoral structure are highly heritable traits. To identify genetic loci underlying variation in these structural phenotypes, we conducted an autosomal genome screen in 309 white sister pairs. Seven structural variables were measured from femoral radiographs and used in multipoint sib-pair linkage analyses. Three chromosomal regions were identified with significant evidence of linkage (log10 of the odds ratio [LOD] > 3.6) to at least one femoral structure phenotype. The maximum LOD score of 4.3 was obtained for femur neck axis length on chromosome 5q. Evidence of linkage to chromosome 4q was found with both femur neck axis length (LOD = 3.9) and midfemur width (LOD = 3.5). Significant evidence of linkage also was found to chromosome 17q, with a LOD score of 3.6 for femur head width. Two additional chromosomal regions 3q and 19p gave suggestive (LOD > 2.2) evidence of linkage with at least two of the structure phenotypes. Chromosome 3 showed evidence of linkage with pelvic axis length (LOD = 3.1), midfemur width (LOD = 2.8), and femur head width (LOD = 2.3), spanning a broad (60 cm) region of chromosome 3q. Linkage to chromosome 19 was supported by two phenotypes, femur neck axis length (LOD = 2.8) and femur head width (LOD = 2.8). This study is the first genome screen for loci underlying variation in femoral structure and represents an important step toward identifying genes contributing to the risk of osteoporotic hip fracture in the general population. [source]


Correlations between clinical and historical variables, and cerebral structural variables in people with mild intellectual disability and schizophrenia

JOURNAL OF INTELLECTUAL DISABILITY RESEARCH, Issue 2 2001
T. L. Sanderson
Abstract The increased prevalence of schizophrenia in the population with mildly intellectual disability (ID) remains unexplained. The present study explores several possibilities by examining historical/clinical findings in relation to structural neuroimaging findings in three groups: (1) comorbid mild ID and schizophrenia; (2) schizophrenia alone; and (3) mild ID alone. Information about clinical and historical variables was obtained from 101 subjects (39 with comorbidity, 34 with schizophrenia and 28 with mild ID), out of whom 68 (23, 25 and 20, respectively) had had a cerebral magnetic resonance imaging (MRI) scan. Although a number of significant correlations exist between clinical variables and structural MRI abnormalities in all three groups, no clearly predictive inter- or between-group differences emerged. More striking was the finding that showed small amygdalo-hippocampal size to be associated with a history of central nervous system injury, especially meningitis. These findings provide support for the view that cognitive impairment and comorbid psychosis can result from a common cause, such as meningitis or obstetric complications, possibly interacting with other factors, such as family history. [source]


Synthesis and liquid crystalline properties of poly(1-alkyne)s carrying triphenylene discogens

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 9 2008
Changmin Xing
Abstract Triphenylene-containing 1-decynes with different alkyl chain lengths and their polymers are synthesized and the effects of the structural variables on their mesomorphic properties are investigated. The monomers [HCC(CH2)8CO2C18H6 (OCmH2m+1)5; m = 4,9] are prepared by consecutive etherization, coupling, and esterification reactions. The monomers form columnar phases at room temperature. The polymerizations of the monomers are effected by [Rh(nbd)Cl]2, producing soluble polymers in high yields (up to 84%). The structures and properties of the polymers are characterized and evaluated by IR, NMR, TGA, DSC, POM, and XRD analyses. All the polymers are thermally stable, losing little of their weights when heated to 300 C. The isotropization temperature of the polymers increases initially with the length of alkyl chain but decreases on further extension. Although the polymers with shorter and longer alkyl chain lengths adopt a homogeneous hexagonal columnar structure, those with intermediate ones form mesophases with mixed structures. 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2960,2974, 2008 [source]


Eurosiberian meadows at their southern edge: patterns and phytogeography in the NW Tien Shan

JOURNAL OF VEGETATION SCIENCE, Issue 2 2009
Viktoria Wagner
Abstract Question: What are the community types, underlying gradients and phytogeographical affinities of montane meadows in the western Tien Shan? Location: Aksu-Jabagly Nature Reserve, South Kazakhstan, Middle Asia. Methods: Species composition, structural and environmental variables were studied in 98 plots. Species composition was classified by cluster analysis and gradients explored using NMDS. Relationships between species richness, environmental and structural variables were investigated with regression analysis. Phytogeographic patterns were assessed by examining species distribution types. Results: Seven community types were distinguished by cluster analysis. Three axes of the NMDS explained 77% of the variation, showing different overlap of communities with environmental and structural properties. Species richness showed linear relationships with pH, altitude, heat load, soil skeletal content and structural variables. Middle Asian and Eurosiberian species constituted the majority of the species pool and cover. Conclusion: The studied communities represent a unique mixture of Middle Asian and Eurosiberian species that exhibit structural and environmental similarities to Eurosiberian meadows. The Tien Shan mountain meadows can thus be considered an endemic-rich southern outlier of the broader Eurosiberian meadow formation. Shifts in land-use patterns pose a potential threat that deserves more attention from conservationists. [source]


Environmental and neighbourhood effects on tree fern distributions in a neotropical lowland rain forest

JOURNAL OF VEGETATION SCIENCE, Issue 1 2007
Mirkka M. Jones
Abstract Questions: To what extent are the distributions of tropical rain forest tree ferns (Cyatheaceae) related to environmental variation, and is habitat specialization likely to play a role in their local coexistence? Location: Lowland rain forest at La Selva Biological Station, Costa Rica. Methods: Generalized linear (GLM) and generalized additive (GAM) logistic regression were used to model the incidence of four tree fern species in relation to environmental and neighbourhood variables in 1154 inventory plots regularly distributed across 6 km2 of old-growth forest. Small and large size classes of the two most abundant species were modelled separately to see whether habitat associations change with ontogeny. Results: GLM and GAM model results were similar. All species had significant distributional biases with respect to micro-habitat. Environmental variables describing soil variation were included in the models most often, followed by topographic and forest structural variables. The distributions of small individuals were more strongly related to environmental variation than those of larger individuals. Significant neighbourhood effects (spatial autocorrelation in intraspecific distributions and non-random overlaps in the distributions of certain species pairs) were also identified. Overlaps between congeners did not differ from random, but there was a highly significant overlap in the distributions of the two most common species. Conclusions: Our results support the view that habitat specialization is an important determinant of where on the rain forest landscape tree ferns grow, especially for juvenile plants. However, other factors, such as dispersal limitation, may also contribute to their local coexistence. [source]


Socioeconomic Correlates of Rates of Child Maltreatment in Small Communities

AMERICAN JOURNAL OF ORTHOPSYCHIATRY, Issue 1 2010
Asher Ben-Arieh
This study expands the research on neighborhood effects and child maltreatment by examining the structural conditions, including religion and nationality, in small towns in Israel. The results are compared with those in inner-city and suburban neighborhoods in Western countries. Five community structural variables were statistically correlated with investigated cases of child maltreatment: adults' unemployment rate, rate of new immigrants, rate of children in single-parent families, population gain or loss, and the community's location in relation to a central city. A multivariate regression analysis of these variables explained 44% of the variance. [source]


The impact of ageing-in-place policies on structural change in residential aged care

AUSTRALASIAN JOURNAL ON AGEING, Issue 1 2009
Bev Richardson
Objectives:,This paper reports findings from a study to investigate the impact of ageing-in-place policies on resident dependency levels and to explore the relationship between structural variables and outcome ratings. Methods:,The study involved a time series data collection of high- and low-care places and accreditation ratings from both the first and the second accreditation cycles in Queensland (N = 482 and 499). Paired-samples t-tests were also conducted on a sample of homes providing both high- and low-level care to assess changing dependency levels over the two time periods. Results:,A statistically significant increase (0.005) was found in the proportion of residents classified as high care living in low-care homes between the first and the second accreditation cycles. Conclusions:,The findings suggest that the ageing-in-place regulatory intervention achieved the intended policy goal and homes have effectively implemented staffing and quality control strategies to accommodate the changes. [source]


Updating an input,output table for use in policy analysis

AUSTRALIAN JOURNAL OF AGRICULTURAL & RESOURCE ECONOMICS, Issue 4 2000
Benjamin L. Buetre
The long lag in the publication of input,output tables is one of the central constraints in applied general equilibrium analysis. Model builders often use out-dated databases leading to analyses that are inappropriate for the policy questions being addressed. This occurs particularly when there exists a significant structural change in the economy. We discuss the updating of an input,output table of the Philippines by simulation technique. A detailed computable general equilibrium model of the Philippine economy with comparative static and forecasting capabilities is utilised. The data are drawn from known percentage changes of macroeconomic variables such as those in the national accounts and structural variables such as employment and output by industry. [source]