787 research outputs found
Effect of high pressure on multiferroic BiFeO3
We report experimental evidence for pressure instabilities in the model
multiferroic BiFeO3 and namely reveal two structural phase transitions around 3
GPa and 10 GPa by using diffraction and far-infrared spectroscopy at a
synchrotron source. The intermediate phase from 3 to 9 GPa crystallizes in a
monoclinic space group, with octahedra tilts and small cation displacements.
When the pressure is further increased the cation displacements (and thus the
polar character) of BiFeO3 is suppressed above 10 GPa. The above 10 GPa
observed non-polar orthorhombic Pnma structure is in agreement with recent
theoretical ab-initio prediction, while the intermediate monoclinic phase was
not predicted theoretically.Comment: new version, accepted for publication in Phys. Rev.
Immersive multi-user decision training games with ARLearn
Serious gaming approaches so far focus mainly on skill development, motivational aspects or providing immersive learning situations. Little work has been reported to foster awareness and decision competencies in complex deci-sion situations involving incomplete information and multiple stakeholders. We address this issue exploring the technical requirements and possibilities to de-sign games for such situations in three case studies: a hostage taking situation, a multi-stakeholder logistics case, and a health-care related emergency case. To implement the games, we use a multi-user enabled mobile game development platform (ARLearn). We describe the underlying real world situations and edu-cational challenges and analyse how these are reflected in the ARLearn games realized. Based on these cases we propose a way to increase the immersiveness of mobile learning games.SALOM
Benefits of supportive strategies for carers of people with high-grade glioma: a systematic review: Strategies for addressing the needs of high-grade glioma carers
Purpose: To systematically review and examine current evidence for the carer-reported benefits of supportive care strategies for carers of adults with high-grade glioma (HGG). Methods: Four databases (CINAHL, EMBASE, PubMed, PsycINFO) were searched for articles published between January 2005 and April 2022 that assessed strategies for addressing the supportive care needs of carers of adults with HGG (WHO grade 3–4). Study selection and critical appraisal were conducted independently by three authors (DJ/MC, 2021; DJ/RJ 2022). Data extraction was conducted by one author (DJ) and checked by a second author (RJ). Results were synthesised narratively. Results: Twenty-one studies involving 1377 caregivers were included, targeting the carer directly (n = 10), the patient-carer dyad (n = 3), or focused on people with HGG + / − their carers (n = 8). A paucity of high-quality evidence exists for effective and comprehensive support directly addressing outcomes for carers of adults with HGG. Strategies that demonstrated some benefits included those that built carer knowledge or provided emotional support, delivered by health professionals or through peer support. Supportive and early palliative care programmes have potential to reduce unmet carer needs while providing ongoing carer support. Conclusion: Strategies incorporating an educational component, emotional support, and a regular needs assessment with corresponding tailored support are most valued by carers. Future practice development research should adopt a value-based approach and exceed evaluation of efficacy outcomes to incorporate evaluation of the experience of patients, carers, and staff, as well as costs
Non-equilibrium Casimir forces: Spheres and sphere-plate
We discuss non-equilibrium extensions of the Casimir force (due to
electromagnetic fluctuations), where the objects as well as the environment are
held at different temperatures. While the formalism we develop is quite
general, we focus on a sphere in front of a plate, as well as two spheres, when
the radius is small compared to separation and thermal wavelengths. In this
limit the forces can be expressed analytically in terms of the lowest order
multipoles, and corroborated with results obtained by diluting parallel plates
of vanishing thickness. Non-equilibrium forces are generally stronger than
their equilibrium counterpart, and may oscillate with separation (at a scale
set by material resonances). For both geometries we obtain stable points of
zero net force, while two spheres may have equal forces in magnitude and
direction resulting in a self-propelling state.Comment: 6 pages, 6 figure
Trace formulae for non-equilibrium Casimir interactions, heat radiation and heat transfer for arbitrary objects
We present a detailed derivation of heat radiation, heat transfer and
(Casimir) interactions for N arbitrary objects in the framework of
fluctuational electrodynamics in thermal non-equilibrium. The results can be
expressed as basis-independent trace formulae in terms of the scattering
operators of the individual objects. We prove that heat radiation of a single
object is positive, and that heat transfer (for two arbitrary passive objects)
is from the hotter to a colder body. The heat transferred is also symmetric,
exactly reversed if the two temperatures are exchanged. Introducing partial
wave-expansions, we transform the results for radiation, transfer and forces
into traces of matrices that can be evaluated in any basis, analogous to the
equilibrium Casimir force. The method is illustrated by (re)deriving the heat
radiation of a plate, a sphere and a cylinder. We analyze the radiation of a
sphere for different materials, emphasizing that a simplification often
employed for metallic nano-spheres is typically invalid. We derive asymptotic
formulae for heat transfer and non-equilibrium interactions for the cases of a
sphere in front a plate and for two spheres, extending previous results. As an
example, we show that a hot nano-sphere can levitate above a plate with the
repulsive non-equilibrium force overcoming gravity -- an effect that is not due
to radiation pressure.Comment: 29 pages, 6 figures (v2: Sentence added in Sec. 1
The Atacama Cosmology Telescope: The LABOCA/ACT Survey of Clusters at All Redshifts
We present a multi-wavelength analysis of eleven Sunyaev Zel'dovich effect
(SZE)-selected galaxy clusters (ten with new data) from the Atacama Cosmology
Telescope (ACT) southern survey. We have obtained new imaging from the Large
APEX Bolometer Camera (345GHz; LABOCA) on the Atacama Pathfinder EXperiment
(APEX) telescope, the Australia Telescope Compact Array (2.1GHz; ATCA), and the
Spectral and Photometric Imaging Receiver (250, 350, and ;
SPIRE) on the Herschel Space Observatory. Spatially-resolved 345GHz SZE
increments with integrated S/N > 5 are found in six clusters. We compute 2.1GHz
number counts as a function of cluster-centric radius and find significant
enhancements in the counts of bright sources at projected radii . By extrapolating in frequency, we predict that the combined
signals from 2.1GHz-selected radio sources and 345GHz-selected SMGs contaminate
the 148GHz SZE decrement signal by ~5% and the 345GHz SZE increment by ~18%.
After removing radio source and SMG emission from the SZE signals, we use ACT,
LABOCA, and (in some cases) new Herschel SPIRE imaging to place constraints on
the clusters' peculiar velocities. The sample's average peculiar velocity
relative to the cosmic microwave background is .Comment: 19 pages, 11 figures, Accepted for Publication in The Astrophysical
Journa
A Natural Experiment on Innovation Without Patents
Innovation occurs within a complex web of law. Of the myriad legal doctrines that affect innovation, the most directly relevant is intellectual property, particularly patent law. The United States Constitution, in Article I, Section 8, states a strong public policy goal for the granting of patents (and copyrights) to inventors: “To promote the Progress of Science and useful Arts, by securing for limited Times to Authors and Inventors the exclusive Right to their respective Writings and Discoveries.” Despite the Founding Fathers’ apparent faith in the societal benefits afforded by patent protection, a crescendo of recent critics have accused the patent system of complicating, slowing, or even thwarting innovation. Patents certainly present significant hurdles for open and user innovation. Moreover, von Hippel (2005) and Strandburg (2008) have demonstrated that user innovators, especially individuals, tend to be poorly served, and often harmed, by the patent system
On decoding and rewriting genomes: a psychoanalytical reading of a scientific revolution
In various documents the view emerges that contemporary biotechnosciences are currently experiencing a scientific revolution: a massive increase of pace, scale and scope. A significant part of the research endeavours involved in this scientific upheaval is devoted to understanding and, if possible, ameliorating humankind: from our genomes up to our bodies and brains. New developments in contemporary technosciences, such as synthetic biology and other genomics and “post-genomics” fields, tend to blur the distinctions between prevention, therapy and enhancement. An important dimension of this development is “biomimesis”: i.e. the tendency of novel technologies and materials to mimic or plagiarize nature on a molecular and microscopic level in order to optimise prospects for the embedding of technological artefacts in natural systems such as human bodies and brains. In this paper, these developments are read and assessed from a psychoanalytical perspective. Three key concepts from psychoanalysis are used to come to terms with what is happening in research laboratories today. After assessing the general profile of the current revolution in this manner, I will focus on a particular case study, a line of research that may serve as exemplification of the vicissitudes of contemporary technosciences, namely viral biomaterials. Viral life forms can be genetically modified (their genomes can be rewritten) in such a manner that they may be inserted in human bodies in order to produce substances at specific sites such as hormones (testosterone), neurotransmitters (dopamine), enzymes (insulin) or bone and muscle tissue. Notably, certain target groups such as top athletes, soldiers or patients suffering from degenerative diseases may become the pioneers serving as research subjects for novel applications. The same technologies can be used for various purposes ranging from therapy up to prevention and enhancement
From tacit knowledge to visual expertise: Eye-tracking support in maritime education and training
The maritime pilot is an expert with knowledge on a specific navi- gational route. The maritime pilot cadet undergoes maritime education and training in classrooms, onboard vessels and in simulators. Developing visual expertise is a basic objective. Transferring knowledge from experienced mar- itime pilots to maritime pilot cadets is challenging since some of this knowledge is tacit. The transference is achieved by externalization and socialization pro- cesses. The objective of this pre-study was to assess eye-tracking methodology as a tool to support maritime education and training, and for transferring tacit knowledge. The study was performed in an explorative way during simulator sessions, by interviews, questionnaires and observations. The result shows that eye-tracking methodology is useful for transferring tacit knowledge in simulator settings, but not during other parts of the education and training. The results also show that situational awareness of maritime pilot instructors and maritime pilot cadets increases when utilizing eye-tracking methodology
The Atacama Cosmology Telescope: Sunyaev-Zel'dovich Selected Galaxy Clusters at 148 GHz from Three Seasons of Data
[Abridged] We present a catalog of 68 galaxy clusters, of which 19 are new
discoveries, detected via the Sunyaev-Zel'dovich effect (SZ) at 148 GHz in the
Atacama Cosmology Telescope (ACT) survey of 504 square degrees on the celestial
equator. A subsample of 48 clusters within the 270 square degree region
overlapping SDSS Stripe 82 is estimated to be 90% complete for M_500c > 4.5e14
Msun and 0.15 < z < 0.8. While matched filters are used to detect the clusters,
the sample is studied further through a "Profile Based Amplitude Analysis"
using a single filter at a fixed \theta_500 = 5.9' angular scale. This new
approach takes advantage of the "Universal Pressure Profile" (UPP) to fix the
relationship between the cluster characteristic size (R_500) and the integrated
Compton parameter (Y_500). The UPP scalings are found to be nearly identical to
an adiabatic model, while a model incorporating non-thermal pressure better
matches dynamical mass measurements and masses from the South Pole Telescope. A
high signal to noise ratio subsample of 15 ACT clusters is used to obtain
cosmological constraints. We first confirm that constraints from SZ data are
limited by uncertainty in the scaling relation parameters rather than sample
size or measurement uncertainty. We next add in seven clusters from the ACT
Southern survey, including their dynamical mass measurements based on galaxy
velocity dispersions. In combination with WMAP7 these data simultaneously
constrain the scaling relation and cosmological parameters, yielding \sigma_8 =
0.829 \pm 0.024 and \Omega_m = 0.292 \pm 0.025. The results include
marginalization over a 15% bias in dynamical mass relative to the true halo
mass. In an extension to LCDM that incorporates non-zero neutrino mass density,
we combine our data with WMAP7+BAO+Hubble constant measurements to constrain
\Sigma m_\nu < 0.29 eV (95% C. L.).Comment: 32 pages, 21 figures To appear in J. Cosmology and Astroparticle
Physic
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