73 research outputs found
Onset of Mechanical Stability in Random Packings of Frictional Spheres
No full textUsing sedimentation to obtain precisely controlled packings of noncohesive spheres, we find that the volume fraction ?RLP of the loosest mechanically stable packing is in an operational sense well defined by a limit process. This random loose packing volume fraction decreases with decreasing pressure p and increasing interparticle friction coefficient ?. Using x-ray tomography to correct for a container boundary effect that depends on particle size, we find for rough particles in the limit p?0 a new lower bound, ?RLP=0.550±0.001
Corrigendum: The Body Odor Disgust Scale (BODS): Development and validation of a novel olfactory disgust assessment [Chem. Senses, (2016) (1-10)] doi: 10.1093/chemse/bjw107
No full textIn "The Body Odor Disgust Scale (BODS): Development and Validation of a Novel Olfactory Disgust Assessment" by Marco Tullio Liuzza et al., the sentence in section "Confirmatory factor analysis", "One hundred sixty-eight participants (49.6%) defined themselves as female." should be "One hundred twenty-eight participants (49.6%) defined themselves as female.". This has been corrected in print and online. The author regrets this error
(U-Th)/He thermochronometry: Mapping 3D geometry using micro-X-ray tomography and solving the associated production-diffusion equation
No full textInternational audience(UTh)/He ages reflect the combined effects of He (á particles) loss due to diffusion and He ingrowth due to radioactive decay of U and Th series. Furthermore, the á particles are emitted with sufficient kinetic energy that they can travel, in theory, up to 20 ìm and as a result, á particles may be ejected beyond the crystal edges. To circumvent this problem a correction factor must be applied, which is essentially based on the geometry of the crystals [Farley, K. A., Wolf, R., and Silver, L. (1996). The effect of long alpha-stopping distances on (UTh)/He dates. Geochimica et Cosmochimica Acta, 60:42234229]. This strongly limits the application of the technique to crystals of appropriate geometries. We present here a method to compute the effects of á-ejection for (UTh)/He dating by taking into account the 3D morphology of individual crystals determined with micro-X-ray tomography. We also develop a model which solves the diffusion equation for the crystals that have been imaged. We then couple this model with an inversion algorithm to extract the range of thermal histories that the rocks may have experienced. This technique is applied to detrital samples from rocks collected in the Southern Alps of New Zealand, a region of high exhumation rate
Surface chemistry and tip-sample interactions in atomic force microscopy
No full textMicrofabricated silicon nitride cantilevers with integral tips are commonly employed in atomic force microscopy. The link between surface chemistry, including surface group acid-base dissociation and counterion complexation, and tip-sample interaction in aqueous electrolyte solution is examined. Silicon nitride tip interaction with "flat plate" samples of both muscovite mica and silicon nitride as a function of aqueous solution pH and electrolyte concentration is investigated. The long-range component of the interaction is normalized with respect to an effective tip radius, and as a result electrical double layer and van der Waals interactions can be discussed quantitatively. Microfracture and tribochemical tip wear is also discussed with reference to atomic force microscope contact mode imaging. Non-retarded Hamaker constants are reported for a range of silicon nitride, silica, silicon and muscovite mica systems.Peer-reviewe
Examination of the geometry of long-range tip—sample interaction in atomic force microscopy
No full textMaking your finances tangible: A service proposition for a new financial platform
No full textThe challenge addressed within this master thesis is to decide on the next focus area for Equip as an early-stage startup regarding new proposition development. Equip is a Fintech startup currently developing a financial coaching platform to be offered to employees paid by their employer. For employers, it is a valuable strategy to improve employees’ financial wellbeing since financial stress results in lower productivity, increased absenteeism and lower retention. In addition, improving employees’ financial wellbeing can also attract young and new talent while maintaining current employees. The most common reasons early-stage startups fail are lack of resources and insufficient customer research, resulting in the absence of good product market fit. The platform involves a complex stakeholder field: two types of customers, namely the employer and its employees, and in addition to these, the service supplier in the form of several financial experts. The researcher of this master thesis has identified each of these actors’ motivation to use and interact with Equip. Different stakeholders' needs and value indicators were discovered through literature, user interviews, generative sessions and internal analysis of Equip. During a joint prioritisation session with Equip’s team, the identified needs were assessed according to the expected customer and business value they would generate.The prioritisation resulted in the focus area: Providing personal guidance during the first steps users have to take to secure their financial future so that they stop procrastinating.A new proposition, i.e. the Financial Roadmap, was developed through ideation and experimentation. The Financial Roadmap enables users to simulate the effect of specific financial decisions (i.e. life events) on the development of their financial situation over time. This allows users to think ahead of their financial future by putting a plan together and making their finances more tangible. Given that measuring the impact on the repeat usage rate by implementing the Financial Roadmap is impossible since this requires full implementation and time, a Minimal Viable Product is presented to validate the concept further. A product roadmap and operational roadmap show how the designed concept and its MVP fit within the bigger picture of Equip’s development as a startup to accomplish its vision of becoming the go-to platform to manage your entire financial life.Strategic Product Desig
Late Devonian antiarch remains (placoderm fish) from the Gilberton Formation, north Queensland
No full textNew Devonian fish remains are described from the lower part of the Gilberton Formation of north Queensland, the first identifiable specimens found since the original specimen was described in 1936. They include the first determinable dermal skull bones from this deposit. Some dermal bones of the trunk armour are closely associated, and of similar size with morphology consistent with coming from the same fish, permitting a provisional reconstruction of the ventral wall of trunk armour. The new morphological evidence indicates a form close to the antiarch Remigolepis, and a likely age of late Famennian for the lower fossiliferous strata of the Gilberton Formation.GCY
acknowledges Professors Tim Senden and
Adrian Sheppard for provision of facilities in
the Research School of Physics and Department
of Applied Mathematics, ANU, and funding
under Australian Research Council Discovery
grants DP1092870 and DP140104161. CJB
acknowledges the provision of facilities by
the Queensland Museum
Contact Angles of Aqueous Solutions on Copper Surfaces Bearing Self-Assembled Monolayers
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