1,319 research outputs found
The magnetic exciton of EuS revealed by resonant inelastic x-ray scattering
We report the valence-to-core resonant inelastic x-ray scattering (RIXS) of
EuS measured at the L3 edge of Eu. The obtained data reveal two sets of
excitations: one set is composed of a hole in the S 3p bands and an electron
excited to extended Eu 5d band states, the other is made up from a hole in the
Eu 4f states and an electron in localized Eu 5d states bound to the 4f hole by
its Coulomb potential. The delocalized excitations arise from the
dipole-allowed 5d to 2p emissions, whereas the localized excitations result
from the dipole-forbidden (quadrupole-allowed) 4f to 2p emissions. Both these
emission channels have a comparable intensity thanks to a small number of
occupied 5d states (approximately 0.6) combined with a large number of occupied
4f states (seven). We identify the localized electron-hole pairs with the
"magnetic excitons" suggested in the past as an interpretation of the sharp
features seen in the optical absorption spectra. Our observations provide a
direct experimental evidence of these excitons which has been missing up to
now.Comment: 7 pages, 4 figures, supplemental material (PDF, 8 pages) added as an
ancillary fil
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Tablet Keyboard Configuration Affects Performance, Discomfort and Task Difficulty for Thumb Typing in a Two-Handed Grip
When holding a tablet computer with two hands, the touch keyboard configuration imposes postural constraints on the user because of the need to simultaneously hold the device and type with the thumbs. Designers have provided users with several possible keyboard configurations (device orientation, keyboard layout and location). However, potential differences in performance, usability and postures among these configurations have not been explored. We hypothesize that (1) the narrower standard keyboard layout in the portrait orientation leads to lower self-reported discomfort and less reach than the landscape orientation; (2) a split keyboard layout results in better overall outcomes compared to the standard layout; and (3) the conventional bottom keyboard location leads to the best outcomes overall compared to other locations. A repeated measures laboratory experiment of 12 tablet owners measured typing speed, discomfort, task difficulty, and thumb/wrist joint postures using an active marker system during typing tasks for different combinations of device orientation (portrait and landscape), keyboard layout (standard and split), and keyboard location (bottom, middle, top). The narrower standard keyboard with the device in the portrait orientation was associated with less discomfort (least squares mean (and S.E.) 2.9±0.6) than the landscape orientation (4.5±0.7). Additionally, the split keyboard decreased the amount of reaching required by the thumb in the landscape orientation as defined by a reduced range of motion and less MCP extension, which may have led to reduced discomfort (2.7±0.6) compared to the standard layout (4.5±0.7). However, typing speed was greater for the standard layout (127±5 char./min.) compared to the split layout (113±4 char./min.) regardless of device orientation and keyboard location. Usage guidelines and designers can incorporate these findings to optimize keyboard design parameters and form factors that promote user performance and usability for thumb interaction
Hydrodynamic model for three-phase internal- and external-loop airlift reactors
A mathematical model predicting the hydrodynamic behaviour of three-phase airlift reactors, working with low-density solids and
with high solids loading, was developed. The model allows for the prediction of local gas holdup and liquid velocity in airlift
bioreactors. Model was validated for an external-loop airlift reactor and an internal-loop airlift reactor with an enlarged degassing
zone, being a good agreement obtained between calculated and experimental data.Fundação para a Ciência e a Tecnologia (FCT)
Junta Nacional de Investigação Científica e Tecnológica (JNICT) - PRAXIS 2/2.1/BIO/1061/95
Instituto de Biotecnologia e Química Fina (IBQF) - GGP XXI/BD/2937/9
Modelling design of multiphase bubble-bed reactors for advanced food-industry technologies
Project Copernicu
Modelling design of multiphase bubble-bed reactors for advanced food-industry applications
An EC project (IC15-CT98-0904 / PL979021) under this title commenced November 1998
courtesy of Dr Jindrich Zahradnik, sadly since deceased. In dedication to his memory overviewed
here are contributions from the four partners whose lead investigators appear as authors (plus
coordinator as corresponding author) with principals and researchers recognised in cited
literature. A website (www.copernicus.aston.ac.uk) has been launched to disseminate major
individual components and collaborations facilitated by study exchanges, also envisaged
exploitation by industries. Drawing on this material we outline partners' established expertise and
its unification under EC umbrella funding. To avoid confusion on due credit for contributions,
references are designated by first letters of the above-named authors. At risk of appearing to
favour ones' own wares, we humbly refer readers to our cited papers for contextual
commentaries
Characterization of bubbles in a bubble column by image analysis
Fundação para a Ciência e a
Tecnologia (FCT); EC
Pedigree analysis of Czech Holstein calves with schistosoma reflexum
<p>Abstract</p> <p>Background</p> <p>Schistosoma reflexum (SR) is congenital syndrome briefly characterized by visceral eventration, severe dorsoflexion and ankylosis of the spine and arthrogryposis. A genetic etiology has been proposed, but conclusive evidence has not yet been provided.</p> <p>Methods</p> <p>Pedigree analysis was carried out in 29 cases of SR in Czech Holsteins and Holstein crosses. Genetic relationship was evaluated and inbreeding coefficients calculated. Pedigrees of 15 Czech Holsteins fathering non-SR affected calves were used for comparison.</p> <p>Results</p> <p>Twenty-one cases occurred in one pedigree founded by three sires while three SR calves occurred in another pedigree with a common grandfather. The sex ratio between affected males and females was 11:6. Affected calves shared common ancestors different from those shared by the unaffected calves. The inbreeding coefficient in the SR affected calves was not increased compared to unaffected calves.</p> <p>Conclusions</p> <p>The findings are consistent with SR being inherited autosomal recessively. Further studies are however needed to confirm this and therefore a breeding trial is recommended where a suspected heterozygous sire is mated to closely related females.</p
Miyabeacin: A new cyclodimer presents a potential role for willow in cancer therapy
Willow (Salix spp.) is well known as a source of medicinal compounds, the most famous being salicin, the progenitor of aspirin. Here we describe the isolation, structure determination, and anti-cancer activity of a cyclodimeric salicinoid (miyabeacin) from S. miyabeana and S. dasyclados. We also show that the capability to produce such dimers is a heritable trait and how variation in structures of natural miyabeacin analogues is derived via cross-over Diels-Alder reactions from pools of ortho-quinol precursors. These transient ortho-quinols have a role in the, as yet uncharacterised, biosynthetic pathways around salicortin, the major salicinoid of many willow genotypes
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