Identifying the energy gap: magnitude and determinants of 5-year weight gain in midage women

Objective: The aims of this study were to estimate average yearly weight gain in midage women and to identify the determinants of weight gain and gaining weight at double the average rate.
Research Methods and Procedures: The study sample comprised 8071 participants (45 to 55 years old) in the Australian Longitudinal Study on Women's Health who completed mailed surveys in 1996, 1998, and 2001.
Results: On average, the women gained almost 0.5 kg per year [average 2.42 kg (95% confidence interval, 2.29 to 2.54) over 5 years]. In multivariate analyses, variables associated with energy balance (physical activity, sitting time, and energy intake), as well as quitting smoking, menopause/hysterectomy, and baseline BMI category were significantly associated with weight gain, but other behavioral and demographic characteristics were not. After adjustment for all of the other biological and behavioral variables, the odds of gaining weight at about twice the average rate (>5 kg over 5 years) were highest for women who quit smoking (odds ratio = 2.94; 95% confidence interval, 2.17, 3.96). There were also independent relationships between the odds of gaining >5 kg and lower levels of habitual physical activity, more time spent sitting, energy intake (but only in women with BMI > 25 at baseline), menopause transition, and hysterectomy.
Discussion: The average weight gain equates with an energy imbalance of only about 10 kcal or 40 kJ per day, which suggests that small sustained changes in the modifiable behavioral variables could prevent further weight gain.

Application of submerged membrane bioreactor for aquaculture effluent reuse

Discharging the nutrient rich aquaculture effluents into inland water bodies and oceans is becoming a serious concern due to the adverse effect that brings in the form of eutrophication and subsequent damages to those waters. A laboratory scale biological reactor consisting of a denitrifying compartment followed by a submerged membrane bioreactor (SMBR) compartment was used to treat 40 L d−1 of aquaculture effluent with an average concentration of 74 mg L−1 nitrate (NO3 − ). Sugar was added to the aquaculture effluent in order that to enter into the denitrifying compartment at a carbon: nitrogen ratio (C:N) of 2:1 and 4:1. A hollow fibre membrane with a pore size of 0.4 μm and a filtration area of 0.20 m2 was used in the SMBR and was operated at an average flux of 0.20 m3 m−2 d−1. An intermittent suction period of 12 min followed by a relaxation period of 3 min was maintained in the SMBR throughout the experiment. Different aeration rates of 1, 3, 5 and 10 Lpm were applied to the SMBR to determine the rate of membrane fouling and 5 Lpm aeration rate was found to be optimum with respect to the rate of fouling of membrane at a C:N ratio of 4:1. The average rate of fouling at 1, 3, 5 and 10 Lpm were 1.17, 0.70, 0.48 and 0.52 kPa d−1, respectively. The increase in the rate of fouling when the aeration was increased from 5 to 10 Lpm may be due to the breakage of suspended particles into finer particles which could have increased the fouling of membrane. It was also found that increasing the C:N ratio from 2:1 to 4:1 resulted in more cake being formed on the membrane surface as well as an increase in the reduction of NO3 − from 64% to 78%. Preliminary calculations show that 2.4 to 3.2 g of suspended solids could be accumulated per square meter of membrane surface before physical cleaning of membrane is required (at a transmembrane pressure of 20 kPa).

Prospective evaluation of respiratory exacerbations in children with cystic fibrosis from newborn screening to 5 years of age

Background Newborn screening allows novel treatments for cystic fibrosis (CF) to be trialled in early childhood before irreversible lung injury occurs. As respiratory exacerbations are a potential trial outcome variable, we determined their rate, duration and clinical features in preschool children with CF; and whether they were associated with growth, lung structure and function at age 5 years. Methods: Respiratory exacerbations were recorded prospectively in Australasian CF Bronchoalveolar Lavage trial subjects from enrolment after newborn screening to age 5 years, when all participants underwent clinical assessment, chest CT scans and spirometry. Results 168 children (88 boys) experienced 2080 exacerbations, at an average rate of 3.66 exacerbations per person-year; 80.1% were community managed and 19.9% required hospital admission. There was an average increase in exacerbation rate of 9% (95% CI 4% to 14%; p<0.001) per year of age. Exacerbation rate differed by site (p<0.001) and was 26% lower (95% CI 12% to 38%) in children receiving 12 months of prophylactic antibiotics. The rate of exacerbations in the first 2 years was associated with reduced forced expiratory volume in 1 s z scores. Ever having a hospitalmanaged exacerbation was associated with bronchiectasis (OR 2.67, 95% CI 1.13 to 6.31) in chest CT scans, and lower weight z scores at 5 years of age (coefficient -0.39, 95% CI -0.74 to -0.05). Conclusions Respiratory exacerbations in young children are markers for progressive CF lung disease and are potential trial outcome measures for novel treatments in this age group.

Savings provisions in Australian electoral law : their forms, functions and historical development

The introduction of universal suffrage in 1902 established voting as a right for adult Australians who were British subjects and over 21 years of age. However, parties, parliaments, and electoral authorities have not been content with merely ensuring that citizens are entitled to vote. They have also enacted measures that aim to maximise citizen participation in elections. Turnout was made compulsory in 1925, which largely solved the ‘problem’ of voluntary abstention from the ballot box. A second concern has been disenfranchisement caused by incorrectly completed ballot papers. This situation arises when a voter submits a ballot that fails to comply with the legal requirements for a formal vote. Since the introduction of compulsory voting, debates about how to improve electoral turnout have largely concentrated on how to reduce rates of informality.The ‘problem’ of informality has long occupied the attention of electoral authorities and policy makers. This is due, in part, to the fact that rates of informality in Australia have been consistently high relative to other mature democracies. Moreover, the prevailing view in much of the Australian literature is that most informal voting is the result of mistakes and therefore ‘accidental’ or ‘unintentional’. Estimates of unintentional informal voting at national elections vary, but usually fall within the range of 80 to 85 per cent of informal votes cast. Even by the more conservative estimates of the Australian Electoral Commission (‘AEC’) the average rate of unintentional voting in the four national elections conducted in the period between 2001 and 2010 was 60.45 per cent.

Cigarette smoking is negatively associated with family average income among urban and rural men in regional Mainland China

Socio-economic status (SES) has a strong influence on cigarette smoking behaviour. However, as a more sensitive and realistic index of SES, family average income (FAI) has little studied regarding its association with smoking. With a response rate of 90.1%, a cross-sectional study was conducted among randomly selected urban-rural participants (n  = 29,353) between October of 2000 and March of 2001 in Nanjing, China. The proportion of male participants who were current smokers was 54.7%; for females it was 2.2%. After adjustment for possible confounding variables (area of residence, age, education, occupation) males in the middle (OR 0.76; 95% CI 0.69–0.84) and higher (OR 0.64; 95% CI 0.57–0.71) FAI tertiles had lower odds of being smokers than did males in the lower FAI tertile. There were no differences by FAI category in the odds of being an ex-smoker. Therefore, current smoking among adult males is inversely associated with family average income in a regional Chinese population. FAI may inform the targeting of campaigns or other initiatives, particularly in populations where material prosperity is low in some social groups.

Family average income and diagnosed Type 2 diabetes in urban and rural residents in regional mainland China.

Aims: To explore the relationship between family average income (FAI; an index of socio-economic status) and Type 2 diabetes in a region of mainland China. Methods: Population-based cross-sectional study, conducted between October 2000 and March 2001 in administrative villages (n = 45) randomly selected from three urban districts and two rural counties of NanJing municipality, mainland China, with a regional population of 5.6 million. Participants were all local residents aged ≥ 35 years old (n = 29 340); 67.7% from urban areas, 32.3% from rural areas, 49.8% male and 50.2% female. Results: The response rate of eligible participants was 90.1%. The overall prevalence of self-reported Type 2 diabetes was 1.9%. After adjustment for possible confounding variables (age, gender, area of residence, body mass index, educational level, smoking status, occupational and leisure-time physical activity), participants in the higher and middle FAI categories were more than twice as likely to have Type 2 diabetes as those in the lower FAI category. Conclusions: The prevalence of Type 2 diabetes is positively related to socio-economic status (indexed by FAI) in Chinese at the population level. After controlling for potential confounding factors, people in higher socio-economic status groups are more likely to have Type 2 diabetes. These associations are consistent with other effects of epidemiological transition and identify a need for preventive initiatives.

Family average income and body mass index above the healthy weight range among urban and rural resicents in regional Mainland China

Objective: To explore the relationship between family average income (FAI; an index of socio-economic status) and body mass index (BMI; a widely used, inexpensive indicator of weight status) above the healthy weight range in a region of Mainland China. Design: Population-based cross-sectional study, conducted between October 1999 and March 2000 on a sample of regular local residents aged 35 years or older who were selected by random cluster sampling. Setting: Forty-five administrative villages selected from three urban districts and two rural counties of Nanjing municipality, Mainland China, with a regional population of 5.6 million. Subjects: In total, 29 340 subjects participated; 67.7% from urban and 32.3% from rural areas; 49.8% male and 50.2% female. The response rate among eligible participants was 90.1%. Results: The proportion of participants classified as overweight was 30.5%, while 7.8% were identified as obese. After adjusting for possible confounding variables (age, gender, area of residence, educational level, occupational and leisure-time physical activity, daily vegetable consumption and frequency of red meat intake), urban participants were more likely to be overweight or obese relative to their rural counterparts, more women than men were obese, and participants in the lowest FAI tertile were the least likely to be above the healthy weight range. Conclusions: The proportion of adults with BMI above the healthy weight range was positively related to having a higher socio-economic status (indexed by FAI) in a regional Chinese population.

Influence of stocking rate and mixed grazing of Angora goats and Merino sheep on animal and pasture production in southern Australia : 3 : mohair and wool production and quality

The effects of animal species (AS; Angora goats, Merino sheep, mixed-grazed goats and sheep at the ratio of 1:1) and stocking rate (SR; 7.5, 10 and 12.5 animals/ha) on fibre production and quality were determined in a replicated experiment on improved annual temperate pastures in southern Australia from 1981 to 1984. Separately grazed sheep produced the most total clean fibre/ha at each SR. Mixed-grazed treatments produced amounts of clean fibre/ha similar to the arithmetic mean of sheep and goat treatments at 7.5/ha (21.9 versus 21.3 kg/ha), 10% more at 10/ha (28.3 versus 25.3 kg/ha, P < 0.05) and 7% more at 12.5/ha (31.6 versus 29.6 kg/ha, P < 0.10). Clean wool production/head was affected by AS and SR but not year. Clean mohair production was affected by SR and year but not AS. Variation in mean fibre diameter (MFD) accounted for 67 and 71%, respectively, of the variation in clean wool and clean mohair production/head. There was an AS SR interaction for clean fibre production/t pasture. Growth rate of mohair was highest in autumn and least in summer. In each season, an increase in the SR reduced the clean mohair growth rate. Growth rate of wool was highest in spring and least in summer. Wool and mohair MFD were affected by an AS SR interaction. Mohair MFD was also affected by year and season. At 10/ha, wool from mixed-grazed sheep had a greater MFD than wool from separately grazed sheep (20.2 versus 18.9 μm) and mixed-grazed goats grew mohair 1 μm coarser than separately grazed goats. At 12.5/ha mixed-grazed goats grew mohair 1.9 μm finer than separately grazed goats. Mohair MFD was predicted by a multiple regression that included average liveweight for the period of fleece growth, season of growth (summer 1 μm finer than winter) and year (range 1.27 μm). Mohair MFD increased 4.7 μm/10 kg increase in average fleece-free liveweight (P = 6.4 10-14). Fleece-free liveweight alone accounted for 76.4% of the variation in mohair MFD. There was an AS SR interaction for the incidence of kemp and medullated fibres; under severe grazing pressure their incidence was suppressed. This experiment indicated that the principles associated with the effects of SR on wool production on annual temperate pastures apply to mohair production. Mixed grazing of Merino sheep and Angora goats produced complementary and competitive effects depending on the SR. Angora goats should not be grazed alone or mixed-grazed with sheep on annual temperate pastures at SR greater than that recommended for Merino sheep.

What is rate? Does context or representation matter?

Rate is an important, but difficult, mathematical concept. Despite more than 20 years of research, especially with calculus students, difficulties are reported with this concept. This paper reports the results from analysis of data from 20 Australian Grade 10 students. Interviews targeted students’ conceptions of rate, focussing on the influence of representation and context on their expression of their understanding of rate. This analysis shows that different representations of functions provide varying levels of rate-related information for individual students. Understandings of rate in one representation or context are not necessarily transferred to another representation or context. Rate is an important, but commonly misunderstood, mathematical concept with many everyday applications (Swedosh, Dowsey, Caruso, Flynn, & Tynan, 2007). It is a complicated concept comprising many interwoven ideas such as the ratio of two numeric, measurable quantities but in a context where both quantities are changing. In mathematics classes, this is commonly expressed as change in the dependent variable resulting from a unit change in the independent variable, and variously described as constant or variable rate; average or instantaneous rate. In addition, rate may be seen as a purely abstract mathematical notion or embedded in the understanding of real-world applications. This paper explores the research question: Are students’ expressions of their conceptions of rate affected by either context or mathematical representation? This question was part of a larger study (Herbert, 2010) conducted with Grade 10 students from the Australian state of Victoria.

Metabolic rate and membrane fatty acid composition in birds : a comparison between long-living parrots and short-living fowl

Both basal metabolic rate (BMR) and maximum lifespan potential (MLSP) vary with body size in mammals and birds and it has been suggested that these are mediated through size-related variation in membrane fatty acid composition. Whereas the physical properties of membrane fatty acids affect the activity of membrane proteins and, indirectly, an animal's BMR, it is the susceptibility of those fatty acids to peroxidation which influence MLSP. Although there is a correlation between body size and MLSP, there is considerable MLSP variation independent of body size. For example, among bird families, Galliformes (fowl) are relatively short-living and Psittaciformes (parrots) are unusually long-living, with some parrot species reaching maximum lifespans of more than 100 years. We determined BMR and tissue phospholipid fatty acid composition in seven tissues from three species of parrots with an average MLSP of 27 years and from two species of quails with an average MLSP of 5. 5 years. We also characterised mitochondrial phospholipids in two of these tissues. Neither BMR nor membrane susceptibility to peroxidation corresponded with differences in MLSP among the birds we measured. We did find that (1) all birds had lower n-3 polyunsaturated fatty acid content in mitochondrial membranes compared to those of the corresponding tissue, and that (2) irrespective of reliance on flight for locomotion, both pectoral and leg muscle had an almost identical membrane fatty acid composition in all birds.

Genetic correlation between resting metabolic rate and exploratory behaviour in deer mice (Peromyscus maniculatus)

According to the ‘pace-of-life’ syndrome hypothesis, differences in resting metabolic rate (RMR) should be genetically associated with exploratory behaviour. A large number of studies reported significant heritability for both RMR and exploratory behaviour, but the genetic correlation between the two has yet to be documented. We used a quantitative genetic approach to decompose the phenotypic (co)variance of several metabolic and behavioural measures into components of additive genetic, common environment and permanent environment variance in captive deer mice. We found significant additive genetic variance for two mass-independent metabolic measures (RMR and the average metabolic rate throughout the respirometry run) and two behavioural measures (time spent in centre and distance moved in a novel environment). We also detected positive additive genetic correlation between mass-independent RMR and distance moved (rA = 0.78 ± 0.23). Our results suggest that RMR and exploratory behaviour are functionally integrated traits in deer mice, providing empirical support for one of the connections within the pace-of-life syndrome hypothesis.

Behavioral inference of diving metabolic rate in free-ranging leatherback turtles

Good estimates of metabolic rate in free‐ranging animals are essential for understanding behavior, distribution, and abundance. For the critically endangered leatherback turtle (Dermochelys coriacea), one of the world’s largest reptiles, there has been a long‐standing debate over whether this species demonstrates any metabolic endothermy. In short, do leatherbacks have a purely ectothermic reptilian metabolic rate or one that is elevated as a result of regional endothermy? Recent measurements have provided the first estimates of field metabolic rate (FMR) in leatherback turtles using doubly labeled water; however, the technique is prohibitively expensive and logistically difficult and produces estimates that are highly variable across individuals in this species. We therefore examined dive duration and depth data collected for nine free‐swimming leatherback turtles over long periods (up to 431 d) to infer aerobic dive limits (ADLs) based on the asymptotic increase in maximum dive duration with depth. From this index of ADL and the known mass‐specific oxygen storage capacity (To2) of leatherbacks, we inferred diving metabolic rate (DMR) as . We predicted that if leatherbacks conform to the purely ectothermic reptilian model of oxygen consumption, these inferred estimates of DMR should fall between predicted and measured values of reptilian resting and field metabolic rates, as well as being substantially lower than the FMR predicted for an endotherm of equivalent mass. Indeed, our behaviorally derived DMR estimates ( mL O2 min−1 kg−1) were times the resting metabolic rate measured in unrestrained leatherbacks and times the average FMR for a reptile of equivalent mass. These DMRs were also nearly one order of magnitude lower than the FMR predicted for an endotherm of equivalent mass. Thus, our findings lend support to the notion that diving leatherback turtles are indeed ectothermic and do not demonstrate elevated metabolic rates that might be expected due to regional endothermy. Their capacity to have a warm body core even in cold water therefore seems to derive from their large size, heat exchangers, thermal inertia, and insulating fat layers and not from an elevated metabolic rate.

Influence of growth rate retardation on time budgets and energetics of Arctic Tern Sterna paradisaea and Common Tern S. hirundo chicks

Time budgets of free-living chicks of Arctic Terns Sterna paradisaea and Common Terns S. hirundo throughout development are presented with special reference to changes in time allocation when growth rate varies. Chicks of both species were inactive most of the time observed (87%). Time allocated to the different behaviours changed during development and was generally better correlated with body mass than age. Slower growing nestlings were brooded more and allocated more time to quiescence and less time to locomotion, preening, begging and attacking (the latter two significant only for the Arctic Tern). The energetic implications of variation in time budgets with age and growth rate were considered. Parental brooding resulted in an average energy saving of nearly 40% of an individual nestling's thermoregulatory costs. Whereas thermoregulatory costs remained nearly unchanged in Arctic Tern chicks, these were negatively correlated with growth rate in Common Terns. Tentatively, we estimated a 30% reduction in a nestling's total energy requirement for a 50% reduction in average growth rate for both species.

Habitat switching by Bewick's swans: Maximization of average long-term energy gain?

1. In a system where depletion drives a habitat shift, the hypothesis was tested that animals switch habitat as soon as the average daily net energy intake (or gain) drops below that attainable in the alternative habitat.

2. The study was performed in the Lauwersmeer area. Upon arrival during the autumn migration, Bewick's swans first feed on below-ground tubers of fennel pondweed on the lake, but subsequently switched to feeding on harvest remains in sugar beet fields.

3. The daily energy intake was estimated by multiplying the average time spent foraging per day with the instantaneous energy intake rate while foraging. In the case of pondweed feeding, the latter was estimated from the functional response and the depletion of tuber biomass. In the case of beet feeding, it was estimated from dropping production rate. Gross energy intake was converted to metabolizable energy intake using the assimilation as determined in digestion trials. The daily energy expenditure was estimated by the time-energy budget method. Energetic costs were determined using heart rate.

4. The daily gain of pondweed feeding at the median date of the habitat switch (i.e. when 50% of the swans had switched) was compared with that of beet feeding. The daily gain of beet feeding was calculated for two strategies depending on the night activity on the lake: additional pondweed feeding (mixed feeding) or sleeping (pure beet feeding).

5. The majority of the swans switched when the daily gain they could achieve by staying on the pondweed bed fell just below the average daily gain of pure beet feeders. However, mixed feeders would attain an average daily gain considerably above that of pondweed feeders. A sensitivity analysis showed that this result was robust.

6. We therefore reject the hypothesis that the habitat switch by swans can be explained by simple long-term energy rate maximization. State-dependency, predation risk, and protein requirements are put forward as explanations for the delay in habitat switch.

Assessment of eating rate and food intake in spoon versus fork users in a laboratory setting

Accumulating evidence show positive relationships between eating rate and body weight. Acute food intake is affected by eating rate, bite size, and palatability. The objective was to assess differences between participants who chose to use a spoon vs. fork in eating rate and food intake of four meals that differ in palatability (low vs. high salt) and in energy density (low vs. high fat). Forty-eight healthy adults (16 males, 18-54 y, BMI: 17.8-34.4 kg/m2) were recruited. Participants attended four lunch time sessions after a standardised breakfast. Meals were either (1) low-fat/low-salt, (2) low-fat/high-salt, (3) high-fat/low-salt, or (4) high-fat/high-salt. Nineteen participants (6 males) consistently used a fork and 21 (8 males) used a spoon, 8 participants were inconsistent in cutlery use and excluded from analyses. Spoon users had on average a higher BMI than fork users (p=0.006). Effects of cutlery use, BMI status (BMI<25 vs. BMI>25), salt, and fat, and their interactions were assessed in a General Linear Model. Spoon users consumed faster (fork: 53±2.8g/min; spoon: 62±2.1g/min, p=0.022) and tended to consume more (p=0.09), whereas the duration of the meals were similar (fork: 6.9±0.3min; spoon: 6:7±0.2min, p=0.55). BMI status affected both eating rate and food intake (p=0.005). There were no significant two-way or three-way interactions between salt, fat, and cutlery use on eating rate or food intake. In conclusion, participants who chose to consume with forks ate slower compared to spoon users.