Scalable computation of thermomechanical turbomachinery problems

A commonly held view in the turbomachinery community is that finite element methods are not well-suited for very large-scale thermomechanical simulations. We seek to dispel this notion by presenting performance data for a collection of realistic, large-scale thermomechanical simulations. We describe the necessary technology to compute problems with $O(10^7)$ to $O(10^9)$ degrees-of-freedom, and emphasise what is required to achieve near linear computational complexity with good parallel scaling. Performance data is presented for turbomachinery components with up to 3.3 billion degrees-of-freedom. The software libraries used to perform the simulations are freely available under open source licenses. The performance demonstrated in this work opens up the possibility of system-level thermomechanical modelling, and lays the foundation for further research into high-performance formulations for even larger problems and for other physical processes, such as contact, that are important in turbomachinery analysis.The support of Mitsubishi Heavy Industries is gratefully acknowledged. CNR is supported by EPSRC Grant EP/N018877/1

Hippocampal alterations in glutamatergic signaling during amyloid progression in AβPP/PS1 mice

Our previous research demonstrated that soluble amyloid-β (Aβ)42, elicits presynaptic glutamate release. We hypothesized that accumulation and deposition of Aβ altered glutamatergic neurotransmission in a temporally and spatially dependent manner. To test this hypothesis, a glutamate selective microelectrode array (MEA) was used to monitor dentate (DG), CA3, and CA1 hippocampal extracellular glutamate levels in 2–4, 6–8, and 18–20 month-old male AβPP/PS1 and age- matched C57BL/6J control mice. Starting at 6 months of age, AβPP/PS1 basal glutamate levels are elevated in all three hippocampal subregions that becomes more pronounced at the oldest age group. Evoked glutamate release was elevated in all three age groups in the DG, but temporally delayed to 18–20 months in the CA3 of AβPP/PS1 mice. However, CA1 evoked glutamate release in AβPP/PS1 mice was elevated at 2–4 months of age and declined with age. Plaque deposition was anatomically aligned (but temporally delayed) with elevated glutamate levels; whereby accumulation was first observed in the CA1 and DG starting at 6–8 months that progressed throughout all hippocampal subregions by 18–20 months of age. The temporal hippocampal glutamate changes observed in this study may serve as a biomarker allowing for time point specific therapeutic interventions in Alzheimer’s disease patients

Amyloid-B(42) stimulated hippocampal lactate release is coupled to glutamate uptake

Since brain glucose hypometabolism is a feature of Alzheimer’s disease (AD) progression, lactate utilization as an energy source may become critical to maintaining central bioenergetics. We have previously shown that soluble amyloid-β (Aβ) 42 stimulates glutamate release through the α7 nicotinic acetylcholine receptor (α7nAChR) and hippocampal glutamate levels are elevated in the APP/PS1 mouse model of AD. Accordingly, we hypothesized that increased glutamate clearance contributes to elevated extracellular lactate levels through activation of the astrocyte neuron lactate shuttle (ANLS). We utilized an enzyme-based microelectrode array (MEA) selective for measuring basal and phasic extracellular hippocampal lactate in male and female C57BL/6J mice. Although basal lactate was similar, transient lactate release varied across hippocampal subregions with the CA1 \u3e CA3 \u3e dentate for both sexes. Local application of Aβ 42 stimulated lactate release throughout the hippocampus of male mice, but was localized to the CA1 of female mice. Coapplication with a nonselective glutamate or lactate transport inhibitor blocked these responses. Expression levels of SLC16A1, lactate dehydrogenase (LDH) A, and B were elevated in female mice which may indicate compensatory mechanisms to upregulate lactate production, transport, and utilization. Enhancement of the ANLS by Aβ 42 -stimulated glutamate release during AD progression may contribute to bioenergetic dysfunction in AD

Using Hunter Survey Data To Estimate Wolf Population Sizes In Montana, 2007-2009

Reliable knowledge of the status and trend of carnivore populations is critical to their conservation. In the Northern Rocky Mountains, wildlife managers need a time- and costefficient method for monitoring the large, growing population of gray wolves (Canis lupus) at a state-wide scale. We explored how hunter survey data could be incorporated into a multiyear patch occupancy model framework to estimate the abundance and distribution of wolf packs, wolves, and breeding pairs in Montana for 2007- 2009. We used hunter observations of wolves to estimate the probability that a given landscape patch was occupied by a wolf pack, and used additional data/models in combination with occupancy model output to provide estimates of total number of wolves and number of breeding pairs. Our modeling framework also allowed us to examine how geographic and ecological factors influenced occupancy and detection of wolf packs. Our models provided estimates of number of packs, number of wolves, and number of breeding pairs that were within 20 percent of Montana Fish, Wildlife, and Parks minimum counts for 2007-2009. We found occupancy was positively related to forest cover, rural roads, and elevation and detection probability was positively related to hunter effort and forest cover. We believe that patch occupancy models based on hunter surveys offer promise as a method for accurately monitoring elusive carnivores at state-wide scales in a time- and cost-efficient manner

Numerical modelling of MPA-CVD reactors with the discontinuous Galerkin finite element method

In this article we develop a fully self consistent mathematical model describing the formation of a hydrogen plasma in a microwave power assisted chemical vapour deposition (MPA-CVD) reactor employed for the manufacture of synthetic diamond. The underlying multi-physics model includes constituent equations for the background gas mass average velocity, gas temperature, electromagnetic field energy and plasma density. The proposed mathematical model is numerically approximated based on exploiting the discontinuous Galerkin finite element method. We demonstrate the practical performance of this computational approach on a variety of CVD reactor geometries for a range of operating conditions

Differential rotation measurement of soft X-Ray corona

The aim of this paper is to study the latitudinal variation in the solar rotation in soft X-ray corona. The time series bins are formed on different latitude regions of the solar full disk (SFD) images that extend from 80 degree South to 80 degree North. These SFD images are obtained with the soft X-ray telescope (SXT) on board the Yohkoh solar observatory. The autocorrelation analyses are performed with the time series that track the SXR flux modulations in the solar corona. Then for each year, extending from 1992 to 2001, we obtain the coronal sidereal rotation rate as a function of the latitude. The present analysis from SXR radiation reveals that; (i) the equatorial rotation rate of the corona is comparable to the rotation rate of the photosphere and the chromosphere, (ii) the differential profile with respect to the latitude varies throughout the period of the study; it is more in the year 1999 and least in 1994 and (iii) the equatorial rotation period varies systematically with sunspot numbers and indicates its dependence on the phases of the solar activity cycle.Comment: 9 Pages, 4 Figures, Accepted for Publication in MNRA

Combining Hunter Surveys and Territorial Dynamics to Monitor Wolf Pack Abundance and Distribution in Montana

Carnivores are difficult to monitor on large spatial scales. We developed a patch occupancy model (POM) using hunter surveys to monitor gray wolves (Canis lupus) in Montana, and evaluated the ability of these models to provide wildlife managers with a time-and cost-efficient monitoring technique. We used hunter’s sightings of wolves as our index of occupancy and explored how classifying a patch as occupied based on different minimum number of wolves sighted (1,2,3,4, or 5) or different minimum number of hunters sighting wolves (1,2,3,4,or 5) affected results. We also evaluated how our definition of a “patch” influenced the occupancy estimates by creating POMs with 3 different patch sizes that corresponded to the variation in wolf territory sizes in Montana. We ran multiple models with different patch sizes predicting occupancy classified according to different levels of minimum wolf sightings and minimum hunters seeing wolves. We assessed model accuracy by comparing POM estimates to the Montana Fish, Wildlife, and Parks (FWP) minimum wolf pack count. Our preliminary results showed that patch size did not strongly influence occupancy estimates and that a patch should only be identified as occupied if ? 2 to ? 4 hunters each observed ? 2 to ? 4 wolves in that patch. Within this range, FWP’s minimum wolf pack count fell within the 95-percent confidence interval of POM estimates for 33 percent of the models

Prodromal Glutamatergic Modulation with Riluzole Impacts Glucose Homeostasis and Spatial Cognition in Alzheimer\u27s Disease Mice.

BACKGROUND: Prior research supports a strong link between Alzheimer\u27s disease (AD) and metabolic dysfunction that involves a multi-directional interaction between glucose, glutamatergic homeostasis, and amyloid pathology. Elevated soluble amyloid-β (Aβ) is an early biomarker for AD-associated cognitive decline that contributes to concurrent glutamatergic and metabolic dyshomeostasis in humans and male transgenic AD mice. Yet, it remains unclear how primary time-sensitive targeting of hippocampal glutamatergic activity may impact glucose regulation in an amyloidogenic mouse model. Previous studies have illustrated increased glucose uptake and metabolism using a neuroprotective glutamate modulator (riluzole), supporting the link between glucose and glutamatergic homeostasis. OBJECTIVE: We hypothesized that targeting early glutamatergic hyperexcitation through riluzole treatment could aid in attenuating co-occurring metabolic and amyloidogenic pathologies with the intent of ameliorating cognitive decline. METHODS: We conducted an early intervention study in male and female transgenic (AβPP/PS1) and knock-in (APPNL - F/NL - F) AD mice to assess the on- and off-treatment effects of prodromal glutamatergic modulation (2-6 months of age) on glucose homeostasis and spatial cognition through riluzole treatment. RESULTS: Results indicated a sex- and genotype-specific effect on glucose homeostasis and spatial cognition with riluzole intervention that evolved with disease progression and time since treatment. CONCLUSION: These findings support the interconnected nature of glucose and glutamatergic homeostasis with amyloid pathology and petition for further investigation into the targeting of this relationship to improve cognitive performance