Effects of replication on measured S-N curves of metals

Replication, or repeated tests at the same stress amplitude, is used to provide statistical confidence in life data during the development of S-N curves. This paper discusses the effects of replication on the measurement of S-N curves and presents an alternative to traditional replication methods for the determination of S-N curves, particularly for the development of preliminary S-N curves. Using specimens made out of the extruded bars of a magnesium alloy, it is demonstrated that the S-N curve estimated using the data from non-replication tests is almost same as that from replication tests. The advantage of using non-replication fatigue tests is that it uses fewer specimens, in this instance, only half of that required for 50% replication fatigue test, to achieve the same estimation as that of the replication fatigue tests. Another advantage of using non-replication fatigue tests is that it can detect the non-linearity using limited specimens.

A comparison of two methods in acquiring stimulus-response curves with transcranial magnetic stimulation

Background
The stimulus–response (S–R) curve is a well accepted constituent in transcranial magnetic stimulation (TMS) studies. However, it has been suggested that parameters of the S–R curve differ when stimuli are provided in a “ramped” (measured steps from low to high intensity), or “random” fashion.

Hypothesis
We hypothesized that there would be no difference in the parameters of the S–R curve between either methodologies.

Methods
Using a randomised cross-over design, 10 healthy participants (29.6 ± 6.4 yrs, 3 f) completed “ramped” or “random” curves in biceps brachii (BB) and first dorsal interosseous (FDI) muscles of both limbs. Curves were compared using mixed-factor ANOVA and correlated between limbs and methodologies.

Results
No differences (P > 0.05) and high correlations (range 0.71–0.97; P < 0.001) were observed in BB and FDI data between curves.

Conclusions
This study demonstrated that either methodology provides similar parameters of the S–R curve in healthy participants.

Effects of time since fire on birds : how informative are generalized fire response curves for conservation management?

Fire is both a widespread natural disturbance that affects the distribution of species and a tool that can be used to manage habitats for species. Knowledge of temporal changes in the occurrence of species after fire is essential for conservation management in fire-prone environments. Two key issues are: whether postfire responses of species are idiosyncratic or if multiple species show a limited number of similar responses; and whether such responses to time since fire can predict the occurrence of species across broad spatial scales. We examined the response of bird species to time since fire in semiarid shrubland in southeastern Australia using data from surveys at 499 sites representing a 100-year chronosequence. We used nonlinear regression to model the probability of occurrence of 30 species with time since fire in two vegetation types, and compared species' responses with generalized response shapes from the literature. The occurrence of 16 species was significantly influenced by time since fire: they displayed six main responses consistent with generalized response shapes. Of these 16 species, 15 occurred more frequently in mid- or later-successional vegetation (>20 years since fire), and only one species occurred more often in early succession (<5 years since fire). The models had reasonable predictive ability for eight species, some predictive ability for seven species, and were little better than random for one species. Bird species displayed a limited range of responses to time since fire; thus a small set of fire ages should allow the provision of habitat for most species. Postfire successional changes extend for decades and management of the age class distribution of vegetation will need to reflect this timescale. Response curves revealed important seral stages for species and highlighted the importance of mid- to late-successional vegetation (>20 years). Although time since fire clearly influences the distribution of numerous bird species, predictive models of the spatial distribution of species in fire-prone landscapes need to incorporate other factors in addition to time since fire.

Shifting curves? Trends in thinness and obesity among Australian youth, 1985 to 2010

Objective To describe 25-year trends in the prevalence of ≤Grade 2 thinness and obesity among Australian children by sex, age and socioeconomic (SES) background.

Methods Cross-sectional surveys of New South Wales school-aged children aged 6.0–16.9 years conducted in 1985–1997–2004–2010 (n = 19 434). Height/weight were measured, and thinness and obesity were defined by international standards. SES was derived from children's residential postcode using the Australian Bureau of Statistics' Index of Relative Socioeconomic Disadvantage, most proximal to the survey year.

Results Since 1985, the prevalence of thinness has not varied by survey year. Age was not associated with thinness; however, thinness was lower among middle SES boys, compared with high SES (OR: 0.45, 95%CI: 0.21, 0.97). The prevalence of obesity trebled between 1985 and 1997 (1.7% vs. 5.1% P = 0.000); however, since 1997, obesity prevalence has not significantly changed. Since 1997, obesity was higher among younger compared with older girls (OR: 2.11, 95%CI: 1.48, 3.00) and SES was inversely associated with obesity in boys (OR: 2.05, 95%CI: 1.44, 2.92) and girls (OR: 1.86, 95%CI: 1.27, 2.74).

Conclusions The apparent plateau in child obesity is a welcome finding; however, the SES gradients are of concern. If the obesity stabilization is associated with the impact of multiple lifestyle behavioural interventions, the findings suggest obesity programmes have done ‘no harm’, but potentially the dose/delivery of interventions has not been sufficient or appropriate to reduce child obesity levels.

Individual variation in thermal performance curves: swimming burst speed and jumping endurance in wild-caught tropical clawed frogs

The importance of studying individual variation in locomotor performance has long been recognized as it may determine the ability of an organism to escape from predators, catch prey or disperse. In ectotherms, locomotor performance is highly influenced by ambient temperature (Ta), yet several studies have showed that individual differences are usually retained across a Ta gradient. Less is known, however, about individual differences in thermal sensitivity of performance, despite the fact that it could represent adaptive sources of phenotypic variation and/or additional substrate for selection to act upon. We quantified swimming and jumping performance in 18 wild-caught tropical clawed frogs (Xenopus tropicalis) across a Ta gradient. Maximum swimming velocity and acceleration were not repeatable and individuals did not differ in how their swimming performance varied across Ta. By contrast, time and distance jumped until exhaustion were repeatable across the Ta gradient, indicating that individuals that perform best at a given Ta also perform best at another Ta. Moreover, thermal sensitivity of jumping endurance significantly differed among individuals, with individuals of high performance at low Ta displaying the highest sensitivity to Ta. Individual differences in terrestrial performance increased with decreasing Ta, which is opposite to results obtained in lizards at the inter-specific and among-individual levels. To verify the generality of these patterns, we need more studies on individual variation in thermal reaction norms for locomotor performance in lizards and frogs.

Primary teachers’ algebraic thinking: example from lesson study

Previous studies have reported on primary children’s algebraic thinking and generalising in a range of problem settings but there is little evidence of primary teachers’ knowledge of algebraic thinking. In this paper the development in algebraic thinking of one primary teacher who taught a research lesson in a Japanese Lesson Study project involving teachers from three primary schools is presented. The findings suggest the need for professional learning in algebra and reasoning and indicate the value of Lesson Study.

TensorPack : a Maple-based software package for the manipulation of algebraic expressions of tensors in general relativity

In this paper we: (1) introduce TensorPack, a software package for the algebraic manipulation of tensors in covariant index format in Maple; (2) briefly demonstrate the use of the package with an orthonormal tensor proof of the shearfree conjecture for dust. TensorPack is based on the Riemann and Canon tensor software packages and uses their functions to express tensors in an indexed covariant format. TensorPack uses a string representation as input and provides functions for output in index form. It extends the functionality to basic algebra of tensors, substitution, covariant differentiation, contraction, raising/lowering indices, symmetry functions and other accessory functions. The output can be merged with text in the Maple environment to create a full working document with embedded dynamic functionality. The package offers potential for manipulation of indexed algebraic tensor expressions in a flexible software environment.

Curriculum as colour and curves: a synthesis of Black theory, design and creativity realised as critical curriculum writing

This article looks to three inspirational Black women, bell hooks, Stacey McBride-Irby and Patricia Williams, in the pursuit of radical curriculum. While today curriculum is critiqued as racialised, gendered, sexualised and classed, the formats of curriculum documents such as text books, units of work and lesson plans have changed little. These documents are often conceived as linear sequences of steps leading to outcomes, and their voices are distanced and ‘neutral’. Drawing on a doctoral study of curriculum design in Australia, this article embraces a different approach by opening up a unit of work on girls’ popular culture to hooks’ invocations to teach to transgress, so that curriculum might be experienced as colour and curves, rather than a monochrome route to a pre-determined end point. Through this, along with hooks, I invite teachers to live pedagogy, rather than to deliver it.

Curriculum as colour and curves: a synthesis of black theory, design and creativity realised as critical curriculum writing

This article looks to three inspirational Black women, bell hooks, Stacey McBride-Irby and Patricia Williams, in the pursuit of radical curriculum. While today curriculum is critiqued as racialized, gendered, sexualised and classed, the formats of curriculum documents such as text books, units of work and lesson plans have changed little. These documents are often conceived as linear sequences of steps leading to outcomes, and their voices are distanced and “neutral”. Drawing on a doctoral study of curriculum design in Australia, this article embraces a different approach by opening up a unit of work on girls’ popular culture to hooks’ invocations to teach to transgress, so that curriculum might be experienced as colour and curves, rather than a monochrome route to a pre-determined end point. Through this, along with hooks, I invite teachers to live pedagogy, rather than to deliver it.