170 research outputs found
Development of code evaluation criteria for assessing predictive capability and performance
Computational Fluid Dynamics (CFD), because of its unique ability to predict complex three-dimensional flows, is being applied with increasing frequency in the aerospace industry. Currently, no consistent code validation procedure is applied within the industry. Such a procedure is needed to increase confidence in CFD and reduce risk in the use of these codes as a design and analysis tool. This final contract report defines classifications for three levels of code validation, directly relating the use of CFD codes to the engineering design cycle. Evaluation criteria by which codes are measured and classified are recommended and discussed. Criteria for selecting experimental data against which CFD results can be compared are outlined. A four phase CFD code validation procedure is described in detail. Finally, the code validation procedure is demonstrated through application of the REACT CFD code to a series of cases culminating in a code to data comparison on the Space Shuttle Main Engine High Pressure Fuel Turbopump Impeller
Singlet levels of the NV−centre in diamond
The characteristic transition of theNV− centre at 637 nm is between A
3
2 and E
3 triplet states. There
are also intermediate A
1
1 and E
1 singlet states, and the infrared transition at 1042 nm between these
singlets is studied here using uniaxial stress. The stress shift and splitting parameters are determined,
and the physical interaction giving rise to the parameters is considered within the accepted electronic
model of the centre. It is established that this interaction for the infrared transition is due to a modification
of electron–electron Coulomb repulsion interaction. This is in contrast to the visible 637 nm
transition where shifts and splittings arise from modification to the one-electron Coulomb interaction.
It is also established that a dynamic Jahn–Teller interaction is associated with the singlet E
1 state,
which gives rise to a vibronic level 115 cm−1 above the E
1 electronic state. Arguments associated with
this level are used to provide experimental confirmation that the A
1
1 is the upper singlet level and E
1 is
the lower singlet level.This work was supported by the Australian Research Council (DP 120102232)
Material-Specific Investigations of Correlated Electron Systems
We present the results of numerical studies for selected materials with
strongly correlated electrons using a combination of the local-density
approximation and dynamical mean-field theory (DMFT). For the solution of the
DMFT equations a continuous-time quantum Monte-Carlo algorithm was employed.
All simulations were performed on the supercomputer HLRB II at the Leibniz
Rechenzentrum in Munich. Specifically we have analyzed the pressure induced
metal-insulator transitions in Fe2O3 and NiS2, the charge susceptibility of the
fluctuating-valence elemental metal Yb, and the spectral properties of a
covalent band-insulator model which includes local electronic correlations.Comment: 14 pages, 7 figures, to appear in "High Performance Computing in
Science and Engineering, Garching 2009" (Springer
Tracking individual nanodiamonds in Drosophila melanogaster embryos
Tracking the dynamics of fluorescent nanoparticles during embryonic
development allows insights into the physical state of the embryo and,
potentially, molecular processes governing developmental mechanisms. In this
work, we investigate the motion of individual fluorescent nanodiamonds
micro-injected into Drosophila melanogaster embryos prior to cellularisation.
Fluorescence correlation spectroscopy and wide-field imaging techniques are
applied to individual fluorescent nanodiamonds in blastoderm cells during stage
5 of development to a depth of ~40 \mu m. The majority of nanodiamonds in the
blastoderm cells during cellularisation exhibit free diffusion with an average
diffusion coefficient of (6 3) x 10 \mu m/s, (mean SD).
Driven motion in the blastoderm cells was also observed with an average
velocity of 0.13 0.10 \mu m/s (mean SD) \mu m/s and an average
applied force of 0.07 0.05 pN (mean SD). Nanodiamonds in the
periplasm between the nuclei and yolk were also found to undergo free diffusion
with a significantly larger diffusion coefficient of (63 35) x10
\mu m/s (mean SD). Driven motion in this region exhibited similar
average velocities and applied forces compared to the blastoderm cells
indicating the transport dynamics in the two cytoplasmic regions are analogous.Comment: 20 pages, 6 figure
Nanomechanical sensing using spins in diamond
Nanomechanical sensors and quantum nanosensors are two rapidly developing
technologies that have diverse interdisciplinary applications in biological and
chemical analysis and microscopy. For example, nanomechanical sensors based
upon nanoelectromechanical systems (NEMS) have demonstrated chip-scale mass
spectrometry capable of detecting single macromolecules, such as proteins.
Quantum nanosensors based upon electron spins of negatively-charged
nitrogen-vacancy (NV) centers in diamond have demonstrated diverse modes of
nanometrology, including single molecule magnetic resonance spectroscopy. Here,
we report the first step towards combining these two complementary technologies
in the form of diamond nanomechanical structures containing NV centers. We
establish the principles for nanomechanical sensing using such
nano-spin-mechanical sensors (NSMS) and assess their potential for mass
spectrometry and force microscopy. We predict that NSMS are able to provide
unprecedented AC force images of cellular biomechanics and to, not only detect
the mass of a single macromolecule, but also image its distribution. When
combined with the other nanometrology modes of the NV center, NSMS potentially
offer unparalleled analytical power at the nanoscale.Comment: Errors in the stress susceptibility parameters present in the
original arXiv version have been correcte
Playing in the dark with online games for girls
Pregnant Rapunzel Emergency is part of a series of online free games aimed at young girls (forhergames.com or babygirlgames.com), where dozens of characters from fairy tales, children’s toys and media feature in recovery settings, such as ‘Barbie flu’. The range of games available to choose from includes not only dressing, varnishing nails or tidying messy rooms, but also rather more troubling options such as extreme makeovers, losing weight, or a plethora of baby showers, cravings, hospital pregnancy checks, births (including caesarean), postnatal ironing, washing and baby care. Taking the online game Pregnant Rapunzel Emergency as an exemplar of a current digital trend, the authors explore the workings of ‘dark digital play’ from a number of perspectives – one by each named author. The game selected has (what may appear to adults) several disturbing features in that the player is invited to treat wounds of the kind of harm that might usually be associated with domestic violence towards women
The genome of the Trinidadian guppy, Poecilia reticulata, and variation in the Guanapo population
For over a century, the live bearing guppy, Poecilia reticulata, has been used to study sexual selection as well as local adaptation. Natural guppy populations differ in many traits that are of intuitively adaptive significance such as ornamentation, age at maturity, brood size and body shape. Water depth, light supply, food resources and predation regime shape these traits, and barrier waterfalls often separate contrasting environments in the same river. We have assembled and annotated the genome of an inbred single female from a high-preda- tion site in the Guanapo drainage. The final assembly comprises 731.6 Mb with a scaffold N50 of 5.3 MB. Scaffolds were mapped to linkage groups, placing 95% of the genome assembly on the 22 autosomes and the X-chromosome. To investigate genetic variation in the population used for the genome assembly, we sequenced 10 wild caught male individu- als. The identified 5 million SNPs correspond to an average nucleotide diversity (Ï€) of 0.0025. The genome assembly and SNP map provide a rich resource for investigating adap- tation to different predation regimes. In addition, comparisons with the genomes of other Poeciliid species, which differ greatly in mechanisms of sex determination and maternal resource allocation, as well as comparisons to other teleost genera can begin to reveal how live bearing evolved in teleost fish
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