Resting and peak metabolic rates of Arctic Tern nestlings and their relations to growth rate

We measured resting and peak metabolism in relation to growth rate in arctic tern Sterna paradisaea chicks over the first 10 d after hatching. For chicks with varying growth rate, body mass seems to be a better predictor of resting metabolic rate rather than age. The effect of changes in growth rate on resting metabolism of arctic terms is smaller than found interspecifically in hatchlings. It is possible that difference exist in the heat increment of feeding between fast and slow growers that would further reduce the effect of growth rate on resting metabolism. Chicks that had body masses lower than 75% of that expected for their age were metabolically inferior in withstanding a thermal challenge compared with chicks of the same age but normal mass. In contrast to resting metabolic rate, the extent of peak metabolic rate is related to both body mass and age. This, in part, the maturation of the thermoregulatory system proceeds steadily with time even when body mass lags behind.

Growth rates of the infaunal bivalve Soletellina alba (Lamarck, 1818) (Bivalvia: Psammobiidae) in an intermittent estuary of southern Australia

Caging and a mark–recapture design were used to estimate the growth rate of the brittle, infaunal bivalve Soletellina alba in the Hopkins River estuary. The growth of both caged and uncaged individuals was monitored at three sites near the mouth of the estuary over 180 days. Growth rates did not differ for caged and uncaged bivalves, or for bivalves subject to different amounts of handling, or between sites. Growth did differ between consecutive time intervals, which was attributable to negligible growth occurring during the colder months of autumn/winter. Comparisons of the condition (as indicated by total mass for length³) of S. alba were inconsistent between sites for caged and uncaged bivalves and for those subject to different amounts of handling. Soletellina alba is a rapidly growing bivalve with mean growth rates for the three time intervals being 0.04±0.002 mm day⁻¹ in summer, 0.02±0.001 mm day⁻¹ in autumn and 0.03±0.001 mm day⁻¹ from summer to winter. Using existing literature, it was shown that a significant relationship exists between maximum shell length and onset of sexual maturity in bivalve molluscs. This relationship predicts that S. alba should reach the onset of sexual maturity at 15.8 mm length. Therefore, it appears that it may be possible for juvenile S. alba (<1 mm) to grow, reach sexual maturity and reproduce in between annual mass-mortality events caused by winter flooding.

Using inorganic polymer to reduce leach rates of metals from brown coal fly ash

The burning of brown coal for electricity generation produces thousands of tonnes of fly ash each year. Treatment of the fly ash can reduce leach rates of metals and allow it to be disposed in less prescribed landfill. A geopolymer matrix was investigated as a potential stabilisation method for fly ash obtained from electrostatic precipitators and ash disposal ponds. The ratio of fly ash and geopolymer was varied to determine the effects of different compositions on leaching rates. The major element leachate concentrations obtained from pond ash were lower than that of precipitator fly ash. Conversely, precipitator ash-geopolymers were better for trace heavy metal stabilisation. Effective reduction of elemental concentrations in the leachate has been achieved, particularly for calcium, arsenic, selenium, strontium and barium. Scanning electron microscopy revealed the distribution of metals originated from fly ash and from added geopolymer material. It also showed that some elements are leached from ash particles to the geopolymer phase and others remained as undissolved particles. Qualitative analysis showed that fly ash particles interacted with the geopolymers phase through surface reactions.

Rates of student-reported antisocial behavior, school suspensions, and arrests in Victoria, Australia and Washington State, United States

Background: Few methodologically rigorous international comparisons of student-reported antisocial behavior have been conducted. This paper examines whether there are differences in the frequency of both antisocial behavior and societal responses to antisocial behavior in Victoria, Australia and Washington State, United States. These 2 states were chosen due to their similarities on sociodemographic characteristics and their differences in policy frameworks around problem behavior including antisocial behavior and substance use.

Methods: State representative samples of students (N = 5769) in school grades 5, 7, and 9 in Victoria and Washington State completed a modified version of the Communities That Care self-report survey of behavior and societal responses to behavior. Chi-square analyses compared frequencies of antisocial behavior, school suspensions, and police arrests in the 2 states. Multivariate logistic regression analyses were conducted for each outcome measure to examine the effect of state, controlling for sample design, clustering of students within schools, age, socioeconomic status, and urbanicity.

Results: Few state differences in student-reported antisocial behavior were found, although frequencies varied across behavior type and grade level. Differences in societal responses were observed across grade levels with grade 5 Washington students reporting higher rates of school suspension. Older Washington students reported more arrests.

Conclusions: Rates of student antisocial behavior appear similar in these 2 states in Australia and the United States. However, youth in the United States relative to Australia may experience greater societal consequences for problem behavior. Further research is required to examine the impact of these consequences on subsequent behavior.

Growth and survival rates of large-type sporophytes of Ecklonia cava transplanted to a growth environment with small-type sporophytes

Stipe lengths of sporophytes of Ecklonia cava Kjellman have been reported to be longer along the southeast than southwest coast of the Izu Peninsula, central Japan. Two bays in this region that have natural populations of E. cava, but with different stipe lengths, were chosen for transplant experiments to examine if stipe length was an environmentally controlled trait. Transplant experiments were carried out in order to determine whether large-type sporophytes of E. cava with long stipes growing in Nabeta Bay (southeast Izu Peninsula, Japan) would turn into small-type sporophytes with short stipes when transplanted to Nakagi Bay (southwest Izu Peninsula). Ten juvenile sporophytes of E. cava (stipe length < 5 cm) were collected from Nabeta Bay (large-type habitat) and transplanted to Nakagi Bay (short-type habitat) in December 1995. As a transplant control, ten juvenile sporophytes of E. cava growing in Nakagi Bay were also transplanted to the same artificial reefs. Growth and survival rates of the sporophytes were monitored monthly for 3 y until December 1998. The transplanted sporophytes showed an increase in their stipe length and diameter from winter to spring, whereas almost no increase was observed from summer to autumn. However, the elongation was greater in Nabeta sporophytes than in Nakagi sporophytes. The primary blade length increased mainly from winter to early spring and decreased largely in autumn. Average primary blade lengths were similar in both Nabeta and Nakagi sporophytes from the end of the first year of transplanting. Although ca. 70% of both Nabeta and Nakagi sporophytes survived during the first 2 y after transplantation, no Nakagi sporophytes and only two Nabeta sporophytes survived to the end of the 3 y study period. Despite transplantation to Nakagi Bay, where short sitpes are naturally present, the sporophytes from Nabeta Bay persisted in having longer stipes, which suggests that stipe length is genetically, rather than environmentally, controlled.

HIV, stigma, and rates of infections : a rumour without evidence

The modern concept of a social stigma comes from the work of American sociologist Erving Goffman, who described it as a response to a deeply discrediting attribute that devalues the person [1]. In the medical literature, stigma is almost inevitably written about in terms of adverse social sequelae of a disease—such as leprosy, tuberculosis, epilepsy, schizophrenia, or filariasis [2–6]—or a physical characteristic or functional loss, such as obesity, deafness, or paraplegia [7–9]. The consequences of stigma range from moderate opprobrium at one end of the spectrum to death [10].

Longitudinal surveys of Australian youth : active citizenship and the secondary school experience : community participation rates of Australian youth

LSAY is a research program that follows young Australians as they move through secondary school, into further education or training, and into the labour market and adult life. This website provides access to the electronic full text versions of LSAY research reports, from 1996 to present.

Milk consumption, body composition and pre-weaning growth rates of Australian fur seal

Pre-weaning growth rates, body composition, milk consumption and mass gain efficiency were measured in Australian fur seal Arctocephalus pusillus doriferus pups born in two consecutive breeding periods. Australian fur seals have the highest birth mass of any fur seal species (male 8.3 kg; female 7.2 kg). While their absolute pre-weaning growth rate (male 62 g·day⁻¹; female 53 g·day⁻¹) is similar to that of other temperate latitude fur seals, they have the longest birth-mass doubling time of any otariid species (134–136 days). Daily milk consumption increased from 400 g·day−1 (5 MJ·day−1) after birth to 675 g·day⁻¹ (13.7 MJ·day⁻¹) at age 210 day. However, mean mass-specific milk consumption (41 g·kg⁻¹) is substantially lower than in other otariid species (58–70 g·kg⁻¹) and, combined with a low mass gain efficiency (0.12 g·g⁻¹), contributes to the low mass-specific growth rates observed. There were no significant differences in either absolute or mass-specific milk consumption between the sexes. Significant differences, however, were found between the sexes in the body composition of pups with females generally having larger body lipid stores than males for any given mass. Peak milk yield by Australian fur seal females is estimated at 0.60 MJkg−0.75, substantially less than in Antarctic fur seals. The low level of maternal energy transfer in Australian fur seals may reflect the relatively low marine productivity of their foraging areas.

Maintenance of traditional cultural orientation is associated with lower rates of obesity and sedentary behaviours among African migrant children to Australia

Background: Migrants from developing to developed countries rapidly develop more obesity than the host population. While the effects of socio-economic status on obesity are well established, the influence of cultural factors, including acculturation, is not known.

Objective: To examine the association between acculturation and obesity and its risk factors among African migrant children in Australia.

Design and participants: A cross-sectional study using a non-probability sample of 3- to 12-year-old sub-Saharan African migrant children. A bidimensional model of strength of affiliation with African and Australian cultures was used to divide the sample into four cultural orientations: traditional (African), assimilated (Australian), integrated (both) and marginalized (neither).

Main outcome measures: Body mass index (BMI), leisure-time physical activity (PA) and sedentary behaviours (SBs) and energy density of food.

Results: In all, 18.4% (95% confidence interval (CI): 14–23%) were overweight and 8.6% (95% CI: 6–12%) were obese. After adjustment for confounders, integrated (ß=1.1; P<0.05) and marginalized ß(=1.4; P<0.01) children had higher BMI than traditional children. However, integrated children had significantly higher time engaged in both PA (ß=46.9, P<0.01) and SBs (ß=43.0, P<0.05) than their traditional counterparts. In comparison with traditional children, assimilated children were more sedentary (ß=57.5, P<0.01) while marginalization was associated with increased consumption of energy-dense foods (ß=42.0, P<0.05).

Conclusions: Maintenance of traditional orientation was associated with lower rates of obesity and SBs. Health promotion programs and frameworks need to be rooted in traditional values and habits to maintain and reinforce traditional dietary and PA habits, as well as identify the marginalized clusters and address their needs.

Sexing accuracy and indicators of maturation status in captive Murray cod Maccullochella peelii peelii using non-invasive ultrasonic imagery

Macroscopic- and histological-based assessments of gonad condition were compared with ultrasound images to determine the feasibility of this technology as a non-invasive diagnostic tool for identifying sex and assessing maturation status of Murray cod. Four age-classes (1⁺, 2⁺, 3⁺ and 6⁺ years), were sub-sampled at monthly intervals throughout their annual reproductive cycle and scanned with a 5 MHz linear transducer. An interpretation of sex was made from the resulting images and maximum cross-sectional gonad diameter and area were recorded. Fish were subsequently dissected to confirm gender, and the weights and maturation status of gonads determined and then compared with their respective image profile. Ovaries of females were usually a distinctive feature in ultrasound images, being particularly obvious in older and/or more developed fish. In contrast, the identification of male testis was more problematic. Nonetheless, identifying sex from ultrasound images was consistently achieved by recording the presence/absence of a female ovary (96% total sexing accuracy). Maximum cross-sectional ovary diameter and area were highly correlated with gonad weight (r² = 0.90 and 0.89, respectively) suggesting that indices of maturation status, comparable to the gonadosomatic index (GSI), can be obtained non-destructively from ultrasound scans of females. A less distinct relationship occurred between these dimensions and weight of testes (r² = 0.41). Significant increases (P < 0.05) in mean gonad index (GI, calculated from gonad diameter) occurred for most gonad development stages. However, differences in mean GI between maturation stages were confounded by phenotypic variability, indicating that GI may be limited to population level studies. Nevertheless, ultrasound images of ovaries at each development stage were visually distinctive and enabled qualitative evaluations of maturity, thereby complementing quantitative GI assessments. Repeated serial-monitoring of the same population using ultrasound appears to have great potential for tracking maturation-induced changes in broodfish.

Differential rates of offspring provisioning in Gould’s petrels: are better feeders better breeders?

Procellariiformes (albatrosses and petrels) must accumulate substantial energy reserves to sustain them while incubating their single egg. They then produce a chick that is often more than 130% of their own body mass. Thus, despite the variable nature of resource availability in the marine environment, successful reproduction requires a considerable increase in foraging rates. Birds that are better foragers are, therefore, likely to be better parents. As surrogates of foraging ability, we assessed two parental traits that are separated temporally over the breeding season, body condition during incubation and provisioning performance, in Gould’s petrel (Pterodroma leucoptera). Although parental condition did not influence hatching success, we found significant positive correlations between the average body condition of a breeding pair and both the growth rate of chicks (g day^–1) and the body condition of chicks at peak mass. Provisioning rate also correlated positively with chick condition. Chick condition was positively correlated with haemoglobin concentration [Hb] at peak mass, which was positively correlated with [Hb] at fledging. Because the probability of survival after fledging may be influenced by chick body condition and [Hb], the ability of parents to acquire additional resources for breeding is likely to be an important determinant of reproductive success.

High rates of oxygen reduction over a vapor phase-polymerized PEDOT electrode

The air electrode, which reduces oxygen (O₂), is a critical component in energy generation and storage applications such as fuel cells and metal/air batteries. The highest current densities are achieved with platinum (Pt), but in addition to its cost and scarcity, Pt particles in composite electrodes tend to be inactivated by contact with carbon monoxide (CO) or by agglomeration. We describe an air electrode based on a porous material coated with poly(3,4-ethylenedioxythiophene) (PEDOT), which acts as an O₂ reduction catalyst. Continuous operation for 1500 hours was demonstrated without material degradation or deterioration in performance. O₂ conversion rates were comparable with those of Pt-catalyzed electrodes of the same geometry, and the electrode was not sensitive to CO. Operation was demonstrated as an air electrode and as a dissolved O₂ electrode in aqueous solution.