Diffusion Thermopower at Even Denominator Fractions

We compute the electron diffusion thermopower at compressible Quantum Hall states corresponding to even denominator fractions in the framework of the composite fermion approach. It is shown that the deviation from the linear low temperature behavior of the termopower is dominated by the logarithmic temperature corrections to the conductivity and not to the thermoelectric coefficient, although such terms are present in both quantities. The enhanced magnitude of this effect compared to the zero field case may allow its observation with the existing experimental techniques.Comment: Latex, 12 pages, Nordita repor

Exercise and Polycystic Ovary Syndrome.

Polycystic ovary syndrome (PCOS) is a complex endocrinopathy affecting both the metabolism and reproductive system of women of reproductive age. Prevalence ranges from 6.1-19.9% depending on the criteria used to give a diagnosis. PCOS accounts for approximately 80% of women with anovulatory infer-tility, and causes disruption at various stages of the reproductive axis. Evidence suggests lifestyle modification should be the first line of therapy for women with PCOS. Several studies have examined the impact of exercise interventions on reproductive function, with results indicating improvements in menstrual and/or ovulation frequency following exercise. Enhanced insulin sensitivity underpins the mechanisms of how exercise restores reproductive function. Women with PCOS typically have a cluster of metabolic abnormalities that are risk factors for CVD. There is irrefutable evidence that exercise mitigates CVD risk factors in women with PCOS. The mechanism by which exercise improves many CVD risk factors is again associated with improved insulin sensitivity and decreased hyperinsulinemia. In addition to cardiometabolic and reproductive complications, PCOS has been associated with an increased prevalence of mental health disorders. Exercise improves psychological well-being in women with PCOS, dependent on certain physiological factors. An optimal dose-response relationship to exercise in PCOS may not be feasible because of the highly individualised characteristics of the disorder. Guidelines for PCOS suggest at least 150 min of physical activity per week. Evidence confirms that this should form the basis of any clinician or healthcare professional prescription

Fabrication and characterisation of multi-level lateral nano-devices

The design of surface gate patterns, used to define nanostructurcs in AlGaAs GaAs heterostructures, is greatly enhanced by the possibility of establishing electrical contact to, and independently biasing, a 100 nm wide isolated gate. We describe the fabrication of a multi-level metallisation architecture which can be used to contact a nanoscale central gate and monitor the transition from a quantum dot to ring geometry. We employ geometry induced quantum interference effects as a novel low temperature characterisation tool and report experiments in which the central electrode acts as an artificial impurity. \ua9 1994.Peer reviewed: YesNRC publication: Ye

Critical temperature and critical current of thin-film superfluid 3He

Superfluid3He film flow over the rim of a copper beaker has been measured. The flow rate was measured as a function of temperature and as a function of depth of3He below the rim or film thickness at the rim. The critical current, calculated from the flow rate, varied as (1 -T/Tc p)3/2 as expected for pair-breaking;Tc p is a film-thickness-dependent critical temperature. However, the magnitude of the current was an order of magnitude smaller than expected for pair-breaking, in agreement with other experiments that have demonstrated a lower dissipation mechanism in superfluid3He. The suppression of the critical temperature Tc p/Tc b, where Tc b=0.93 mK is the bulk3He transition temperature, varied from 0.93 to 0.7 as the film thickness at the rim varied from 120 to 90 nm. These ratios are larger than expected from Ginzburg-Landau or microscopic theory of superfluid3He-B. \ua9 1988 Plenum Publishing Corporation.Peer reviewed: YesNRC publication: Ye

Late quaternary environmental change at Lake McKenzie, Southeast Queensland: evidence from microfossils, biomarkers and stable isotope analysis

Unravelling links between climate change and vegetation response during the Quaternary is a research priority, and needed if the climate-environment interactions of modern systems are to be fully understood. Using a sediment core from Lake McKenzie, Fraser Island, we reconstruct changes in the lake ecosystem and surrounding vegetation over the last ca. 36.9 cal kyr BP. Evidence is drawn from multiple sources, including pollen, micro-charcoal, biomarker and stable isotope (C and N) analyses, and is used to improve understanding about the timing and spatial scale of past changes that have occurred locally and in the southeast Queensland region. The glacial period of the record, from ca. 36.9-18.3 cal kyr BP, is characterised by lower lake water levels and increased abundance of, or closer proximity to, plants of the aquatic and littoral zone. High abundance of biomarkers and microfossils of the colonial green alga Botryococcus occur at this time and include high variation in individual botryococcene 13C values. A distinct period of dry or ephemeral conditions at the site is detected during deglaciation, causing a hiatus in the sedimentary record covering the time period from ca. 18.3-14.0 cal kyr BP. The recommencement of sediment accumulation around 14.0 cal kyr BP occurs with evidence of lower fire activity in the area and reduced abundance of terrestrial herbs in the surrounding sclerophyll vegetation. The Lake McKenzie record conforms to existing records from Fraser Island by containing evidence for a mid-Holocene dry period, spanning the time period from ca. 6.1-2.5 cal kyr BP. © The Author

Anthropogenic acceleration of sediment accretion in lowland floodplain wetlands, Murray-Darling Basin, Australia

Over the last decade there has been a deliberate focus on the application of paleolimnological research to address issues of sediment flux and water quality change in the wetlands of the Murray-Darling Basin of Australia. This paper reports on the research outcomes on cores collected from sixteen wetlands along the Murrumbidgee-Murray River continuum. In all sixteen wetlands radiometric techniques and exotic pollen biomarkers were used to establish sedimentation rates from the collected cores. Fossil diatom assemblages were used to identify water source and quality changes to the wetlands. The sedimentation rates of all wetlands accelerated after European settlement, as little as two-fold, and as much as eighty times the mean rate through the Late Holocene. Some wetlands completely infilled through the Holocene, while others have rapidly progressed towards a terrestrial state due to accelerated accretion rates. Increasing wetland salinity and turbidity commenced within decades of settlement, contributing to sediment inputs. The sedimentation rate was observed to slow after river regulation in one wetland, but has accelerated recently in others. The complex history of flooding and drying, and wetland salinisation and eutrophication, influence the reliability of models used to establish recent, fine-resolution chronologies with confidence and the capacity to attribute causes to documented effects. © 2008 Elsevier B.V.Peter Gell, Jennie Fluin, John Tibby, Gary Hancock, Jennifer Harrison, Atun Zawadzki, Deborah Haynes, Syeda Khanum, Fiona Little, Brendan Wals