19 research outputs found
Comprehensive analysis of epigenetic clocks reveals associations between disproportionate biological ageing and hippocampal volume
The concept of age acceleration, the difference between biological age and chronological age, is of growing interest, particularly with respect to age-related disorders, such as Alzheimer’s Disease (AD). Whilst studies have reported associations with AD risk and related phenotypes, there remains a lack of consensus on these associations. Here we aimed to comprehensively investigate the relationship between five recognised measures of age acceleration, based on DNA methylation patterns (DNAm age), and cross-sectional and longitudinal cognition and AD-related neuroimaging phenotypes (volumetric MRI and Amyloid-β PET) in the Australian Imaging, Biomarkers and Lifestyle (AIBL) and the Alzheimer’s Disease Neuroimaging Initiative (ADNI). Significant associations were observed between age acceleration using the Hannum epigenetic clock and cross-sectional hippocampal volume in AIBL and replicated in ADNI. In AIBL, several other findings were observed cross-sectionally, including a significant association between hippocampal volume and the Hannum and Phenoage epigenetic clocks. Further, significant associations were also observed between hippocampal volume and the Zhang and Phenoage epigenetic clocks within Amyloid-β positive individuals. However, these were not validated within the ADNI cohort. No associations between age acceleration and other Alzheimer’s disease-related phenotypes, including measures of cognition or brain Amyloid-β burden, were observed, and there was no association with longitudinal change in any phenotype. This study presents a link between age acceleration, as determined using DNA methylation, and hippocampal volume that was statistically significant across two highly characterised cohorts. The results presented in this study contribute to a growing literature that supports the role of epigenetic modifications in ageing and AD-related phenotypes
HUMAN RESOURCE STRATEGIES IN THE COMMERCIALISATION AND CORPORATISATION OF GOVERNMENT ENTERPRISES
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Final Design of an Air Core, Compulsator Driven 60 Caliber Railgun System
The manufacturing phase of a laboratory-based small-caliber electromagnetic (EM) launcher and compulsator power supply is discussed. The objective of the 29-month program is to develop a compact, lightweight test bed capable of accelerating 32 g masses to 2 km/s at a rate of 10 Hz. Both the power supply and launcher feature significant component design advances which will allow the system to operate at considerably higher energy and power densities than previously demonstrated. The 750 kg compulsator will generate 2.2 kV and the silicon-controlled rectifier (SCR) switch will commutate 386 kA pulses into the 1.6-m long, 0.60 caliber augmented solid armature railgun. The final design and predicted operating characteristics of the compulsator system are described. Overall system performance parameters are reported, including results from the optimization code used to aid in the design of the compulsator system. A system design overview is presented, with emphasis on new materials and state-of-the-art machine components to be used for the first time in a compulsatorCenter for Electromechanic
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Design of a 600 MW Pulsed Air-Core Compulsator
The Center for Electromechanics at The University of Texas at Austin (CEM-UT) is currently in the manufacturing phase of a laboratory based small caliber electromagnetic (EM) launcher and air core compensated pulsed alternator (compulsator) power supply. The two pole, self-excited compulsator features significant component design advances which will allow operation at considerably higher energy (12.3 kJ/kg) and power densities than previously demonstrated. To accomplish this, the generator design features broad use of the current state of the art in materials solid state switching components, and extensive computer modeling. For example, the compulsator features a multilayer composite rotor operating at a tip speed of 530 m/s, silicon nitride ceramic shaft, and silicon nitride rolling element bearings mounted in stationary hydrostatic bearing dampers. Designed specifically for drivmg a small bore augmented railgun, the 750-kg compulsator will operate at 2.2 kV and provide a salvo of current pulses peaking at 386 kA during each discharge cycle. This paper describes the final design and predicted operating characteristics of the compulsator system. Overall system performance parameters are reported, including results from the optimization code used to aid in the design of the compulsator system. A system design overview is presented with emphasis on new materials and state of the art machine components to be used for the first time in a compulsator.Center for Electromechanic