Effects of endurance training status and sex difference on Na+, K+-pump mRNA expression, content and maximal activity in human skeletal muscle

Aim: This study investigated the effects of endurance training status and sex differences on skeletal muscle Na⁺,K⁺-pump mRNA expression, content and activity. Methods: Forty-five endurance-trained males (ETM), 11 recreationally active males (RAM), and nine recreationally active females (RAF) underwent a vastus lateralis muscle biopsy. Muscle was analysed for Na⁺,K⁺-pump α1, α2, α3, β1, β2 and β3 isoform mRNA expression (real-time reverse transcription-polymerase chain reaction), content ([³H]-ouabain-binding site) and maximal activity (3-O-methylfluorescein phosphatase, 3-O-MFPase). Results: ETM demonstrated lower α1, α3, β2 and β3 mRNA expression by 74%, 62%, 70% and 82%, respectively, than RAM (P < 0.04). In contrast, [³H]-ouabain binding and 3-O-MFPase activity were each higher in ETM than in RAM, by 16% (P < 0.03). RAM demonstrated a 230% and 364% higher α3 and b3 mRNA expression than RAF, respectively (P < 0.05), but no significant sex differences were found for α1, α2, β1 or β2 mRNA, [³H]-ouabain binding  or 3-O-MFPase activity. No significant correlation was found between years of endurance training and either [³H]-ouabain binding or 3-O-MFPase activity. Significant but weak correlations were found between the number of training hours per week and 3-O-MFPase activity (r = 0.31, P < 0.02) and between incremental exercise V O_2(peak) and both   [³H]-ouabain binding (r = 0.33, P < 0.01) and 3-O-MFPase activity (r = 0.28, P < 0.03). Conclusions: Isoform-specific differences in Na⁺,K⁺-pump mRNA expression were found with both training status and sex differences, but only training status influenced Na⁺,K⁺-pump content and maximal activity in human skeletal muscle.

Alternating heat transfer between objects of large geometrical difference

The heat transfer on the surface of an object in a gas fluidised bed is sequentially and alternately induced by particle-packet and gas bubble. This phenomenon is studied with computational simulation. The particle-packet and bubble are modelled by a double particle-layers and porous medium model and a hemispherical model, respectively. The heat transfer to and within the object is simulated concurrently. Different grid schemes are applied and different grid sizes are used in meshing the particle-packet and the object as there is a very large difference in their geometrical sizes. Based on theoretical analysis, an approximate method is developed to calculate the heat flux at the surface of the object. The simulation is implemented in a CFD package and the results are compared with experiments.

Foraging behaviour of sympatric Antarctic and subantarctic fur seals: does their contrasting duration of lactation make a difference?

The duration of periods spent ashore versus foraging at sea, diving behaviour, and diet of lactating female Antarctic (Arctocephalus gazella, AFS) and subantarctic (A. tropicalis, SFS) fur seals were compared at Iles Crozet, where both species coexist. The large disparity in lactation duration (SFS: 10 months, AFS: 4 months), even under local sympatry, has led to the expectation that AFS should exhibit higher foraging effort or efficiency per unit time than SFS to allow them to wean their pups in a shorter period of time. Previous evidence, however, has not supported these expectations. In this study, the distribution of foraging trip durations revealed two types of trips: overnight (OFT, <1 day) and long (LFT, >1 day), in common with other results from Macquarie Island. However, diving behaviour differed significantly between foraging trip types, with greater diving effort in OFTs than in LFTs, and diving behaviour differed between fur seal species. OFTs were more frequent in SFS (48%) than in AFS (28%). SFS performed longer LFTs and maternal attendances than AFS, but spent a smaller proportion of their foraging cycle at sea (66.2 vs. 77.5%, respectively). SFS dove deeper and for longer periods than AFS, in both OFTs and LFTs, although indices of diving effort were similar between species. Diel variation in diving behaviour was lower among SFS, which foraged at greater depths during most of the night time available than AFS. The diving behaviour of AFS suggests they followed the nychthemeral migration of their prey more closely. Concomitant with the differences in diving behaviour, AFS and SFS fed on the same prey species, but in different proportions of three myctophid fish (Gymnoscopelus fraseri, G. piabilis, and G. nicholsi) that represented most of their diet. The estimated size of the most important fish consumed did not vary significantly between fur seal species, suggesting that the difference in dive depth was mostly a result of changes in the relative abundance of these myctophids. The energy content of these fish at Iles Crozet may thus influence the amount and quality of milk delivered to pups of each fur seal species. These results contrast with those found at other sites where both species coexist, and revealed a scale of variation in foraging behaviour which did not affect their effort while at sea, but that may be a major determinant of foraging efficiency and, consequently, maternal investment.

Fun or profit : primary students' perceptions of mathematics and science

As the number of students pursuing mathematics and science in higher education decline, it becomes imperative· that we look for the causes of the decline. As part of the Australian Improving Middle Years Mathematics and Science (IMYMS) project, students were asked to rate their perceptions of classroom practice in mathematics and science and their attitudes to these subjects. Results of this survey reveal little difference in perceptions of classroom practice, but significant differences in students' attitudes between mathematics and science. Differences were particularly evident for items relating to the usefulness of mathematics and science (mathematics was more useful) and enjoyment of the subjects (science is more fun). If teachers are aware of such perspectives, it may be possible to change students' attitudes.

Effective student engagement depends on students enjoying their studies in mathematics and science, being confident in their ability and recognising the relevance of these subjects to everyday life, now and in the future.
(Education Training Committee, 2006, p. xvii)

Science and technology are the widely acknowledged foundation of Australia's future development. Underpinning these are the key learning areas of mathematics and science. However, Australia is experiencing a decline in numbers of mathematics and science students in higher education. Moreover, studies over the last two decades have shown a general decline in Australian students' interest and enjoyment of science across the compulsory secondary school years, with a particularly sharp decline across the primary to secondary school transition (e.g. Adams, Doig, & Rosier 1991; Goodrum, Hackling, & Rennie, 200 I) and a decline in the numbers of students studying' advanced mathematical courses in upper secondary school (Thomas, 2000).

Improving teaching and learning in the middle years of schooling (Years 5 to 9) is receiving particular attention because of the coincidence of the disengagement of students with the significance of these years for the preparation of students for their future role in society. Thus the Improving Middle Years Mathematics and Science: The role of subject cultures in school and teacher change (IMYMS) project, which is the source of data for this paper, is investigating the role of mathematics and science' knowledge and subject cultures in mediating change processes in the middle years of schooling.

Mathematics and science are sometimes seen as "love-hate" subjects, rating highest for subjects disliked, but also rating relatively highly among preferred subjects (Hendley & Stables, 1996). Students, even primary aged students, can often shed light on what constitutes good practice (see, for example, 'van den Heuvel-Panhuizen, 2005). Students' attitudes towards mathematics and science and their perceptions of what they regard as positive aspects of classroom practice have been shown to decline from the primary years to junior secondary (Race, 2000). The decline in interest in science in the early years of secondary school is of particular concern, since it is in these years that attitudes to the pursuit of science subjects and careers are formed (Speering & Rennie, 1996). Students' negative attitude towards the relevance of science ,content for their lives was a strong theme in the report by Goodrum, Hackling, & Rennie (2001) on the status and quality of teaching and learning of science.

As part of the IMYMS project, the IMYMS Student Survey was administered to all students in 2004 and 2005. The survey included a 36 item section on students' perceptions of classroom practice and attitudes towards mathematics and science, and a 24 item section on students' learning preferences. Students completed separate, parallel surveys for mathematics and science.

This paper focuses on students' perceptions and attitudes. It explores the differences in 700 Year 5 and 6 students' perceptions of their learning environment and their attitudes to mathematics and science during 2005, the second (and final) year of schools , involvement in the IMYMS project.

Bribery and networking: Is there a difference?

Nature of bribery contrasted with the practice of networking - whether the different moral and legal treatment of the practices is based on principle or simply cultural preference - bribery and the form of networking known as expenditure networking both have the affect of distorting the proper functioning of the market economy by encouraging business decisions to be made on the basis of economically irrelevant considerations - the objective of both practices is to gain a market advantage by providing a 'sweetener' to a person responsible for delegating the provision of goods and services - expenditure networking does have the positive side effect of drawing people together in a social setting.

Clock synchronization state graphs based on clock precision difference

Consistent and stable global states of clock synchronization are very important in distributed and parallel systems. This paper presents an innovative strategy and method to obtain stable global clock synchronization state graphs in asynchronous Internet environments. Our model will introduce the concept of clock precision difference as a means to evaluate running states of all clocks in this system and make this system  self-adaptive well. Finally, we introduce the concept of clock precision difference into global states analysis of clock synchronization and construct clock synchronization state graphs in order to evaluate distributed clock synchronization states. We also present detailed simulations of the strategy and mathematical analysis used on real Internet environments.

Self-adaptive clock synchronisation based on clock precision difference

This paper presents an innovative strategy to synchronize all virtual clocks in asynchronous Internet environments. Our model is based on the architecture of one reference clock and many slave clocks communicating with each other over the Internet. The paper makes three major contributions to this research area. Firstly, one-way information transmission is applied to reduce traffic overhead on the Internet for the purpose of clock synchronization. Secondly, the slave nodes use local virtual time and the arrival timestamp, from the reference node, to create linear mathematical trend models and to retrieve the clock precision differences between reference clock and slave clocks. Finally, a fault-tolerant and self-adaptive model executed by each slave node based on the above linear trend model is created in order to ensure that the virtual clock is running normally, even when the link between the reference node and this slave node has crashed. We also present detailed simulations of this strategy and mathematical analysis on real Internet environments.

Legacies of White Australia : race, culture and nation

The White Australia policy continues to haunt Australia. Here, leading Australian scholars provide an informed debate on the essential issues of race, identity and nation that will determine our attitudes to immigration, multiculturalism and Australian-Asian engagement in the twenty-first century.