Stratifications of Newton polygon strata and Traverso's conjectures for p-divisible groups

The isomorphism number (resp. isogeny cutoff) of a p-divisible group D over an algebraically closed field is the least positive integer m such that D[p^m] determines D up to isomorphism (resp. up to isogeny). We show that these invariants are lower semicontinuous in families of p-divisible groups of constant Newton polygon. Thus they allow refinements of Newton polygon strata. In each isogeny class of p-divisible groups, we determine the maximal value of isogeny cutoffs and give an upper bound for isomorphism numbers, which is shown to be optimal in the isoclinic case. In particular, the latter disproves a conjecture of Traverso. As an application, we answer a question of Zink on the liftability of an endomorphism of D[p^m] to D.Comment: 50 pages, to appear in Annals of Mathematic

Designing a regional e-logistics portal

A variety of optimization and negotiation technologies hold the promise of delivering value to the logistics processes of businesses both small and large, yet they tend to remain inaccessible to SMEs (largely due to price and complexity concerns). This paper describes the early-phase steps in a project to develop a regional e- logistics portal. The project seeks to make constraint-based optimization and automated negotiation technologies accessible to SMEs within a portal that also serves their information needs. The paper highlights several novel aspects of the design of the portal, as well as a novel requirements gathering process involving community consultation

Accuracy of the modified Hardinge approach in acetabular positioning

© 2016 Joule Inc. or its licensors. Background: The surgical approach chosen for total hip arthroplasty (THA) may affect the positioning of the acetabular component. The purpose of this study was to examine the accuracy in orienting the acetabular component using the modified Hardinge approach. Methods: We used our institutional arthroplasty database to identify patients with primary, press-fit, hemispherical acetabular components of a metal-on-polyethylene THA performed between 2003 and 2011. Patients with radiographs obtained 1-3 years after the index procedure were included for measurement of anteversion and inclination angles. Acceptable values of anteversion and abduction angles were defined as 15° ± 10° and 40° ± 10°, respectively. Results: We identified 1241 patients from the database, and the modified Hardinge approach was used in 1010 of the patients included in our analysis. The acetabular component was anteverted in the acceptable zone in 54.1% of patients. The abduction angle was within the defined range in 79.2% of patients. Combined anteversion and abduction angles within the defined zone were present in 43.6% of patients. Conclusion: Consistent with studies examining accuracy from other approaches, our study reveals that the modified Hardinge approach was only moderately accurate in positioning the acetabular component in the acceptable zone

Total sitting time and risk of myocardial infarction, coronary heart disease and all-cause mortality in a prospective cohort of Danish adults

BACKGROUND: Evidence suggests that sitting time is adversely associated with health risks. However, previous epidemiological studies have mainly addressed mortality whereas little is known of the risk of coronary heart disease. This study aimed to investigate total sitting time and risk of myocardial infarction, coronary heart disease incidence and all-cause mortality. METHODS: In the Danish Health Examination Survey (DANHES) conducted in 2007-2008 we tested the hypothesis that a higher amount of daily total sitting time is associated with greater risk of myocardial infarction, coronary heart disease and all-cause mortality. The study population consisted of 71,363 men and women aged 18-99 years without coronary heart disease. Participants were followed for myocardial infarction, coronary heart disease and mortality in national registers to August 10, 2012. Cox regression analyses were performed with adjustment for potential confounders and multiple imputation for missing values. RESULTS: During a mean follow-up period of 5.4 years 358 incident cases of myocardial infarction, 1,446 of coronary heart disease, and 1,074 deaths from all causes were registered. The hazard ratios associated with 10 or more hours of daily sitting compared to less than 6 hours were 1.38 (95% CI: 1.01, 1.88) for myocardial infarction, 1.07 (95% CI: 0.91, 1.27) for coronary heart disease and 1.31 (95% CI: 1.09, 1.57). Compared to sitting less than 6 hours per day and being physically active in leisure time, the hazard ratios of sitting more than 10 hours per day and also being physically inactive in leisure time were 1.80 (95% CI: 1.15, 2.82) for myocardial infarction, 1.42 (95% CI: 1.11, 1.81) for coronary heart disease, and 2.29 (95% CI: 1.82, 2.89) for all-cause mortality. CONCLUSIONS: The results suggest that a higher amount of daily total sitting time is associated with all-cause mortality, particularly among inactive adults. In relation to coronary heart, disease results were less clear. This paper adds new evidence to the limited data on the evidence of sitting time and cardiovascular disease and mortality

Spindown of massive rotating stars

Models of rapidly rotating massive stars at low metallicities show significantly different evolution and higher metal yields compared to non-rotating stars. We estimate the spin-down time-scale of rapid rotating non-convective stars supporting an alpha-Omega dynamo. The magnetic dynamo gives rise to mass loss in a magnetically controlled stellar wind and hence stellar spin down owing to loss of angular momentum. The dynamo is maintained by strong horizontal rotation-driven turbulence which dominates over the Parker instability. We calculate the spin-down time-scale and find that it could be relatively short, a small fraction of the main-sequence lifetime. The spin-down time-scale decreases dramatically for higher surface rotations suggesting that rapid rotators may only exhibit such high surface velocities for a short time, only a small fraction of their main-sequence lifetime.Comment: Accepted by MNRA

Monotone traveling wavefronts of the KPP-Fisher delayed equation

In the early 2000's, Gourley (2000), Wu et al. (2001), Ashwin et al. (2002) initiated the study of the positive wavefronts in the delayed Kolmogorov-Petrovskii-Piskunov-Fisher equation. Since then, this model has become one of the most popular objects in the studies of traveling waves for the monostable delayed reaction-diffusion equations. In this paper, we give a complete solution to the problem of existence and uniqueness of monotone waves in the KPP-Fisher equation. We show that each monotone traveling wave can be found via an iteration procedure. The proposed approach is based on the use of special monotone integral operators (which are different from the usual Wu-Zou operator) and appropriate upper and lower solutions associated to them. The analysis of the asymptotic expansions of the eventual traveling fronts at infinity is another key ingredient of our approach.Comment: 25 pages, 2 figures, submitte

The Effect of Cluster Formation on Graphene Mobility

We investigate the effect of gold (Au) atoms in the form of both point-like charged impurities and clusters on the transport properties of graphene. Cryogenic deposition (18 K) of Au decreases the mobility and shifts the Dirac point in a manner that is consistent with scattering from point-like charged impurities. Increasing the temperature to room temperature promotes the formation of clusters, which is verified with atomic force microscopy. We find that for a fixed amount of Au impurities, the formation of clusters enhances the mobility and causes the Dirac point to shift back towards zero.Comment: 12 pages, 3 figure

Planarian toxicity fluorescent assay: a rapid and cheap pre-screening tool for potential skin irritants

Here we report a new planarian (Dugesia lugubris) fluorescent assay as a rapid and cheap pre-screening tool to predict strong skin irritants. Our aim was to provide a simple and cost-effective in vivo method that avoided use of higher vertebrates. Adapting previously reported methods for planaria mobility alongside an acute toxicity assay, different irritants at five concentrations (0.1%, 0.05%, 0.025%, 0.01% and 0.005% w/v) were tested but both methods failed to discriminate the irritation potential of the test compounds. Therefore, a new alternative fluorescence assay was developed, hypothesising that increasing damage from the irritant to the planarian outer protective membrane will increase accumulation of sodium fluorescein in the flatworm. Fourteen test chemicals were selected representing strong, moderate, mild and non-irritants. In general, results showed increasing sodium fluorescein accumulation within planaria following acute exposure to increasingly strong skin irritants; on exposure to the strong irritants, benzalkonium chloride, citronellal, methyl palmitate, 1-bromohexane and carvacrol, fluorescence within the planaria was significantly greater (P < 0.05) than the negative controls and the common non-irritants PEG-400, dipropylene glycol and isopropyl alcohol; fluorescence values of planaria tested with negative controls and non-irritants were not significantly different. For all test compounds, Fluorescence Intensity of the planaria was compared with literature Primary Irritation Index data and generated a statistically significant (P < 0.005) Pearson correlation (r) of 0.87. Thus, the planarian fluorescent assay is a promising tool for rapid early testing of potential strong skin irritants, and non-irritants, and avoids use of higher vertebrate models

On the fifth anniversary of the Australian Unity Wellbeing Index: what have we learned about subjective wellbeing?

Department of Rehabilitation SciencesRefereed conference pape