The seeds of invasion: enhanced germination in invasive European populations of black locust (Robinia pseudoacacia L.) compared to native American populations.

Local adaptation and the evolution of phenotypic plasticity may facilitate biological invasions. Both processes can enhance germination and seedling recruitment, which are crucial life-history traits for plants. The rate, timing and speed of germination have recently been documented as playing a major role during the invasion process. Black locust (Robinia pseudoacacia L.) is a North American tree, which has spread widely throughout Europe. A recent study demonstrated that a few populations are the source of European black locust. Thus, invasive populations can be compared to native ones in order to identify genetic-based phenotypic differentiation and the role of phenotypic plasticity can thereby be assessed. A quantitative genetics experiment was performed to evaluate 13 juvenile traits of both native and invasive black locust populations (3000 seeds, 20 populations) subjected to three different thermal treatments (18 °C, 22 °C and 31 °C). The results revealed European populations to have a higher germination rate than the native American populations (88% versus 60%), and even when genetic distance between populations was considered. Moreover, this trait showed lower plasticity to temperature in the invasive range than in the native one. Conversely, other studied traits showed high plasticity to temperature, but they responded in a similar way to temperature increase: the warmer the temperature, the higher the growth rate or germination traits values. The demonstrated genetic differentiation between native and invasive populations testifies to a shift between ranges for the maximum germination percentage. This pattern could be due to human-mediated introduction of black locust.

Care needs of persons with long-term spinal cord injury living at home in the Netherlands.

STUDY DESIGN: Cross-sectional survey. OBJECTIVES: To describe the care received, care needs and preventability of secondary conditions according to persons with long-term spinal cord injury (SCI) living at home. SETTING: The Netherlands. METHODS: A questionnaire was sent to all members of the Dutch SCI Patient Organisation. From a list of 26 SCI secondary conditions, participants chose the five conditions they perceived as most important. For each of these conditions, they described the type of care they received, their need for (extra) care and its preventability. RESULTS: Response rate was 45% (n=453) and mean time after injury was 13.3 years. In case of secondary conditions, participants were more likely to visit their general practitioner (58%) than another medical specialist (29%) or rehabilitation specialist (25%). For all most-important secondary conditions, care was received in 47% and care, or extra care, was needed in 41.3%. Treatment was the type of care most often received (29.5%) and needed (17.2%). However, for information and psychosocial care, the care needed (12.2 and 9.9%, respectively) was higher than the care received (7.6 and 5.9%, respectively). Thirty-four percent of all most-important secondary conditions were perceived as preventable, the rate increasing to 52.8% for pressure sores, of which 29.9% were considered to be preventable by the participants themselves. CONCLUSIONS: This study showed substantial unmet care needs in persons with long-term SCI living at home and underlines the further improvement of long-term care for this group. Information, psychosocial care and self-efficacy seem to be the areas to be enhanced.

Hybrid origin and differentiation of two tetraploid Achillea species in East Asia: molecular, morphological and ecogeographical evidence.

Achillea (Asteraceae-Anthemideae) offers classical models for speciation by hybridization and polyploidy. Here, we test the suspected allotetraploid origin of two species, Achillea alpina and Achillea wilsoniana between phylogenetically distinct lineages in East Asia. A total of 421 AFLP bands from 169 individuals and 19 populations of five 2x- and two 4x-species were obtained. The data set was analysed with a newly developed model that accounts for polyploidy and assumes lack of recombination between the parental chromosome sets (i.e. disomic inheritance). A. alpina and A. wilsoniana then appear to be allotetraploids between Achillea acuminata-2x (sect. Ptarmica) and Achillea asiatica-2x (sect. Achillea). The two 4x-species share 44% and 48% of their AFLP bands with A. acuminata-2x, and 39% and 38% with A. asiatica-2x, respectively. Eight plastid haplotypes (A-H) were detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analyses. A. alpina-4x and A. wilsoniana-4x share haplotype F only with A. asiatica-2x. This is consistent with the hybrid origin(s) involving the latter as the maternal ancestor. This result corroborates our previous DNA sequence data, where A. alpina-4x and A. wilsoniana-4x are also placed close to A. asiatica-2x. Morphology, ecology, and amplified fragment length polymorphism (AFLP) profiles of the two 2x-species are distinct, whereas the two 4x-species, grouped as A. alpina aggregate, form a nearly continuous link between them. Considering all evidence, this 4x-aggregate is regarded as the product of a hybridization between genetically distant 2x-ancestors limited to China and adjacent areas: one A. acuminata-like, and the other A. asiatica-like. The allopolyploid A. alpina agg. exhibits considerable morphological variation and ecological flexibility, and has expanded throughout eastern Asia and to northern North America, far beyond the ranges of their presumed 2x-ancestors.

Test-re-test reliability of walking speed, step length and step width measurement after traumatic brain injury: a pilot study.

PRIMARY OBJECTIVE: Assess the test-re-test reliability of walking speed, step length and step width measurement in people with traumatic brain injury (TBI). RESEARCH DESIGN: Repeated measures (two test occasions). METHODS: Thirteen people with TBI completed four comfortable and four fast-paced walking trials of the 10 m walk test and two trials of the 6-minute walk test (6MWT). Walking speed, step length and step width were measured during the 10 m walk test and walking distance and average speed were measured during the 6MWT. The tests were repeated 1-week later. MAIN RESULTS: Walking speed and distance showed excellent test-re-test reliability, with an intra-class correlation coefficient (ICC) of 0.95-0.96. Reliability was also high for step length and width measurement (ICC 0.91-0.98). CONCLUSIONS: This test-re-test reliability means that walking speed and distance and step length and width can be used by physiotherapists to monitor improvements in walking after TBI.

Inter-rater reliability and concurrent validity of walking speed measurement after traumatic brain injury.

OBJECTIVE: To assess the inter-rater reliability and concurrent validity of walking speed measurement after traumatic brain injury. DESIGN: Twelve subjects each completed five comfortably paced and five fast-paced walking trials. Walking speed was measured simultaneously by five observers using a stopwatch (clinical procedure) and by infrared timing gates (gold standard). SETTING: Brain injury rehabilitation unit. SUBJECTS: People with traumatic brain injury who could walk independently and were participating in a rehabilitation programme. MAIN OUTCOME MEASURES: Walking speed over a 10-metre distance. RESULTS: The inter-rater reliability of walking speed measured using a stopwatch was very high, with an intraclass correlation coefficient of at least 0.998 for both comfortable and fast-paced tests. Concurrent validity was excellent for comfortable and fast tests, with perfect correlations between the stopwatch and infrared timing gate measurement procedures. CONCLUSIONS: Physiotherapists can use a stopwatch as a reliable and valid measurement tool to quantify walking speed over a short distance at both comfortable and fast paces in people who have sustained traumatic brain injuries.

Inter-rater reliability and concurrent validity of step length and step width measurement after traumatic brain injury.

PURPOSE: To determine the inter-rater reliability and concurrent validity of step length and step width measurement after traumatic brain injury. METHOD: Twelve people with traumatic brain injury completed six comfortable and six fast paced walking trials over a 10 m distance. Step length and step width were measured by five observers using two procedures. First, using pens taped on the subjects' heels which marked the floor at each heel strike and a tape measure. Second, by videotaping the subjects' feet as they walked on a mat marked with 5 cm grids and using a computer program to digitize foot position and calculate step length and width. RESULTS: The inter-rater reliability of step length and width measurements was very high, with intraclass correlation coefficients between 0.94 and 1.00, for both procedures. Concurrent validity was excellent, with correlations between the procedures ranging from 0.93 to 1.00. However, attaching pens to the heels did cause a slight reduction in right step length and walking speed when walking at a fast or comfortable pace, respectively. CONCLUSIONS: Assessing step length and width using pens taped to the subjects' heels and a tape measure is a reliable and valid clinical measure after traumatic brain injury.

An investigation of the relationship between work and family size decisions over time.

PIP: This longitudinal study finds that wife's labor force participation and family size are spuriously correlated. Research data are from the Panel Study of Young Married Couples collected by the Survey Research Laboratory of the University of Illinois. The sample represents a marriage cohort. In 1972, a list of couples married in August of that year and residing in the Chicago metropolitan area was provided by the Illinois Office of Vital Records. Only those couples in which the husband was aged 30 or less were considered. A random sample of 400 couples was drawn from this group. At the start of the survey, the average age of the women was 21 and men 23. Data used in the study consisted of information collected in 1978 and 1980, after 6 and 8 years of marriage. 2 measures of actual labor force behavior of the wife were taken at each of the 2 points in time. Family size was indicated through 3 measures at each point in time, and achievement motivation of the wife was measured with a 5-point bipolar very positive/very negative scale asking for the evaluation of the wife's attitude toward work. Responses from both the husband and wife served as 2 measures of a latent achievement motivation variable in the key informant methodology. 3 dimensions of sex role norms were measured with Scanzoni's Wife's Self-actualization Scale, Traditional Wife Role Scale, and Problematic Husband Alterations Scale. Responses from both spouses were used. Findings indicate that, except for certain special cases, wife's work and family size are not causally related. Although negatively correlated between themselves, wife's work and family size appear to be mutually dependent on achievement motivation of the wife, sex role norms, and the felt value of children. Thus, when the effects of these antecedents are partialled-out, no evidence for causality exists between wife's work and family size outcomes. Evidence suggests that the spouses in a marriage socially construct their role relationships and this then serves as a common antecedent influencing work and family size choices.^ieng

Labor force participation and fertility: a social analysis of their antecedents and simultaneity.

PIP: The nature of the relationship between labor force participation and fertility is examined for 172 families residing in the Chicago metropolitan area. The sample represents a marriage cohort. The data was collected during the 6th year of marriage (1978). The average age of the wife was 27, that of the husband 29. About 15% of the sample was black, the rest white. The median years of schooling completed was 13 for the wife and 14 for the husband. Median family income (less wife's earnings) was US$15,000; approximately 96% of the husbands and 53% of the wives were employed. The hypothesis is that family decisions are socially constructed through husband and wife interactions wherein individual needs and desires of the spouses are resolved by means of give-and-take and mutual influence. Economic factors, societal forces, group pressures and physiological concerns are presumed to work through the psychological characteristics of the spouses and the social interactions transpiring between them. The is, the exogenous determinants are assumed to constitute the setting or context for individual and social decision making. They either enter as inputs to joint decision making or else shape the needs, desires, or other psychological reactions of spouse prior to decision making. In this study, the specific phenomena to be explained are wife's labor force participation and family size. Also tested is the effect of psychological investment in these 2 issues and the impact of the role relationship between the spouses. The hypotheses are scrutinized at 2 levels of analysis: the individual spouses and the husband-wife dyad. Comparisons are made among social psychological models, wherein either the husband of wife provides information as they perceive their relationship and a sociological model wherein group constructs are formed with the husband and wife acting as informants on the pattern of norms guiding their relation. A A strutural equation methodology is employed to better model measurement error and errors in equations imultaneously. The results show that labor force participation of wife and fertility do not appear to be causally related. Rather, social forces within the family function as common antecedents, thereby producing a spurious observed bivariate association. This implies that labor force participation and fertility decision entail joint decision making and influence. Another implication is that the decision process seems to be neither atomistic nor necessarily sequential. The present study also differs from previous efforts in the methodology employed. Variables were operationalized in concert with sociological theory--social variables were used to explain social outcomes.^ieng

Toward a general theory of fertility: a causal modeling approach.

A general theory of fertility is derived hypothesizing that the demand for children is primarily an outcome of social psychological processes within the family, subject to certain socioeconomic constraints. Two broad social psychological processes are posited as determinants of fertility. The first suggests that the attitudes or tastes of family members influence the demand for children. The second maintains that the nature of the husband-wife interaction (in terms of power, conflict, decision making, and marital satisfaction) determines family size. Socioeconomic variables, in the form of the normative social structure and social stratification, and economic constraints, such as income and price, are hypothesized to influence fertility through their impact on social psychological processes within the family. The overall theory is tested on two independent samples--one in Ankara, Turkey, the second in Mexico City, Mexico--using a structural equation methodology.