Strain localisation patterns under equal-channel angular pressing

Instabilities of plastic flow in the form of localised shear bands were experimentally observed to result from equal-channel angular pressing (ECAP) of magnesium alloy AZ31. The appearance of shear bands and their spacing were dependent on velocity of the pressing and applied back-pressure. A generic gradient plasticity theory involving second-order strain gradient terms in a constitutive model was applied to the case of AZ31 deformed by ECAP. Linear stability analysis was applied to the set of equations describing the deformation behaviour in the process zone idealised as a planar shear zone. A full analytical solution providing a dispersion relation between the rate of growth of a perturbation and the wave number was obtained. It was shown that the pattern of incipient localised shear bands exhibits a spectrum of characteristic lengths corresponding to admissible wave numbers. The interval of the spectrum of wave numbers of viable, i.e. growing, perturbations predicted by linear stability analysis was shown to be in good agreement with the experimentally observed spectrum. The effect of back-pressure applied during ECAP was also considered. The predicted displacement of the shear band spectrum towards lower wave numbers, shown to be a result of the decreased shear strain rate in the shear zone, was consistent with the experimentally observed increase of the band spacing with increased back-pressure. A good predictive capability of the general modelling frame used in conjunction with linear stability analysis was thus demonstrated in the instance of the particular alloy system and the specific processing conditions considered.

Visual pigments, oil droplets, ocular media and cone photoreceptor distribution in two species of passerine bird: the blue tit (Parus caeruleus L.) and the blackbird (Turdus merula L.)

The spectral absorption characteristics of the retinal photoreceptors of the blue tit (Pal trs caeruleus) and blackbird (Turdus merula) were investigated using microspectrophotometry. The retinae of both species contained rods, double cones and four spectrally distinct types of single cone. Whilst the visual pigments and cone oil droplets in the other receptor types are very similar in both species, the wavelength of maximum sensitivity (lambda(max)) of long-wavelength-sensitive single and double cone visual pigment occurs at a shorter wavelength (557 nm) in the blackbird than in the blue tit (563 nm). Oil droplets located in the long-wavelength-sensitive-single cones of both species cut off wavelengths below 570-573 nm, theoretically shifting cone peak spectral sensitivity some 40 nm towards the long-wavelength end of the spectrum. This raises the possibility that the precise lambda(max) of the long-wavelength-sensitive visual pigment is optimised for the visual function of the double cones. The distribution of cone photoreceptors across the retina, determined using conventional light and fluorescence microscopy also varies between the two species and may reflect differences in their visual ecology.

Motivation, readiness to change, and weight loss following adjustable gastric band surgery

High levels of readiness to change (RTC) are considered critical to the long-term success of weight management programs including bariatric surgery. However, there are no data to support this assertion. We hypothesize that RTC level will not influence weight outcomes following surgery. In 227 consecutive patients undergoing adjustable gastric banding surgery, we recorded reasons for seeking surgery, and RTC measured with the University of Rhode Island Change Assessment. Scores were blinded until study completion. The primary outcome measure was percentage of excess BMI loss at 2 years (%EBMIL-2); others included compliance and surgical complications. Of 227 subjects, 204 (90%) had weight measurement at 2 years. There was no significant correlation between RTC score and %EBMIL-2 (r = 0.047, P = 0.5). Using the median split for RTC score the lowest 102 subjects mean %EBMIL-2 was 52.9 ± 26.9% and the highest 52.2 ± 28.3%, P = 0.869. There was no weight loss difference between highest and lowest quartiles, or a nonlinear relationship between weight loss and RTC score. There was no significant relationship between RCT score and compliance, or likelihood of complications. Those motivated by appearance were more likely to be younger women who lost more weight at 2 years. Poor attendance at follow-up visits was associated with less weight loss, especially in men. Measures of RTC did not predict weight loss, compliance, or surgical complications. Caution is advised when using assessments of RTC to predict outcomes of bariatric surgery.

Understanding macrographia in children with autism spectrum disorders

It has been consistently reported that children with autism spectrum disorders (ASD) show considerable handwriting difficulties, specifically relating to accurate and consistent letter formation, and maintaining appropriate letter size. The aim of this study was to investigate the underlying factors that contribute to these difficulties, specifically relating to motor control.

We examined the integrity of fundamental handwriting movements and contributions of neuromotor noise in 26 children with ASD aged 8-13 years (IQ. >. 75), and 17 typically developing controls. Children wrote a series of four cursive letter l's using a graphics tablet and stylus.

Children with ASD had significantly larger stroke height and width, more variable movement trajectory, and higher movement velocities. The absolute level of neuromotor noise in the velocity profiles, as measured by power spectral density analysis, was significantly higher in children with ASD; relatively higher neuromotor noise was found in bands >3. Hz.

Our findings suggest that significant instability of fundamental handwriting movements, in combination with atypical biomechanical strategies, contribute to larger and less consistent handwriting in children with ASD.

Understanding of mental states in later childhood: an investigation of theory of mind in autism spectrum disorder and typical development with a novel task

The developmental trajectories of Theory of Mind (ToM) in later childhood and into adolescence have not been thoroughly investigated, partly due to a lack of sensitive paradigms that can chart development in typical populations or in individuals with a core deficit in ToM, such as those with autism spectrum disorder (ASD). The present study assessed understanding of emotions, beliefs, and intentions using both an established ToM task (Baron‐Cohen et al., 2001) and the more recently developed Comic Strip Task (CST; Cornish et al., 2010). Participants comprised 12 typically-developing (TD) children (mean age: 12·0 years, range: 9·9‐14·8 years) and 12 high-functioning children with ASD (mean age: 11·0 years, range: 9·1‐13·6 years). Results indicated that the ASD group were not impaired on any of the ToM tasks relative to TD children. It was concluded that although children with high-functioning ASD appear to develop basic ToM skills, they do not generalize these to naturalistic situations. The comic-strip paradigm is suggested as a promising way to approach the measurement of ToM across childhood in typical children and those with ASD.

Community-onset Escherichia coli infection resistant to expanded- spectrum cephalosporins in low-prevalence countries

Background
By global standards the prevalence of community onset expanded-spectrum cephalosporin resistant Escherichia coli (ESC-R-EC) remains low in Australia and New Zealand. Of concern, our countries are in a unique position with high extramural resistance pressure from close population and trade links to Asia-Pacific neighbours with high ESC-R-EC rates. We aim to characterize the risks and dynamics of community onset ESC-R-EC in our low-prevalence region.

Methods
A case-control methodology was used. Patients with ESC-R-EC or susceptible E. coli isolated from blood or urine were recruited at six geographically dispersed tertiary hospitals in Australia and New Zealand. Epidemiological data was prospectively collected and bacteria were retained for analysis.

Results
In total, 182 patients (91 cases and 91 controls) were recruited. Multivariate logistic regression identified risk factors for ESC-R amongst E. coli including birth on the Indian subcontinent (OR=11.13, 2.17-56.98, p=0.003), urinary tract infection in the past year (per infection OR=1.430, 1.13-1.82, p=0.003), travel to South East Asia, China, Indian subcontinent, Africa and the Middle East (OR=3.089, 1.29-7.38, p=0.011), prior exposure to trimethoprim+/-sulfamethoxazole &/or an expanded-spectrum cephalosporin (OR=3.665, 1.30-10.35, p=0.014) and healthcare exposure in the previous six months (OR=3.16, 1.54-6.46, p=0.02).

Amongst our ESC-R-EC the blaCTX-M ESBLs was dominant (83% of ESC-R-EC), and the worldwide pandemic clone ST-131 was frequent (45% of ESC-R-EC).

Conclusion
In our low prevalence setting, ESC-R amongst community onset E. coli may be associated with both ‘export’ from healthcare facilities into the community and direct ‘import’ into the community from high-prevalence regions.