3,883 research outputs found
Dynamics from diffraction
A model-independent approach for the extraction of detailed
lattice dynamical information from neutron powder diffraction data is described. The technique is based on a statistical analysis of atomistic configurations generated using reverse Monte Carlo structural refinement.
Phonon dispersion curves extracted in this way are shown to
reproduce many of the important features found in those determined independently using neutron triple-axis spectroscopy. The extent to which diffraction data are sensitive to lattice dynamics is explored in a
range of materials. The prospect that such detailed dynamical information might be accessible using comparatively facile experiments such as neutron
powder diffraction is incredibly valuable when studying systems for which established spectroscopic methods are prohibitive or
inappropriate
Emergence of long-range order in BaTiO3 from local symmetry-breaking distortions
By using a symmetry motivated basis to evaluate local distortions against
pair distribution function data (PDF), we show without prior bias, that the
off-centre Ti displacements in the archetypal ferroelectric BaTiO3 are zone
centred and rhombohedral-like in nature across its known ferroelectric and
paraelectric phases. With our newly-gained insight we construct a simple Monte
Carlo (MC) model which captures our main experimental findings and demonstrate
how the rich crystallographic phase diagram of BaTiO3 emerges from correlations
of local symmetry-breaking distortions alone. Our results strongly support the
order-disorder picture for these phase transitions, but can also be reconciled
with the soft-mode theory of BaTiO3 that is supported by some spectroscopic
techniques.Comment: 5 pages, 3 figure
University lecturers’ adaptability: Examining links with perceived autonomy support, organisational commitment, and psychological wellbeing
In this study, we examined associations between university lecturers’ perceived autonomy support (PAS), adaptability, organisational commitment, and psychological wellbeing. A sample of university lecturers (N = 102) from a single ex-polytechnic higher education institution in the United Kingdom completed validated scales for each construct in the spring term. Inspired by prior work in pre-tertiary education with schoolteachers, a conceptual model of predicted relations was developed and tested using structural equation modelling (SEM). Findings showed that PAS was positively associated with lecturers’ adaptability, organisational commitment, and psychological wellbeing; however, adaptability was unable to influence these outcomes independently of its association with PAS. The findings extend prior work with schoolteachers suggesting that, while adaptability is of importance, its influence may be more salient at pre-tertiary level – where there is typically heightened regulation and lower autonomy – and less salient when autonomy options are wider, as is the case in higher education
Interactive Methods for Teaching Action Potentials, an Example of Teaching Innovation from Neuroscience Postdoctoral Fellows in the Fellowships in Research and Science Teaching (FIRST) Program
Acquiring a faculty position in academia is extremely competitive and now typically requires more than just solid research skills and knowledge of one’s field. Recruiting institutions currently desire new faculty that can teach effectively, but few postdoctoral positions provide any training in teaching methods. Fellowships in Research and Science Teaching (FIRST) is a successful postdoctoral training program funded by the National Institutes of Health (NIH) providing training in both research and teaching methodology. The FIRST program provides fellows with outstanding interdisciplinary biomedical research training in fields such as neuroscience. The postdoctoral research experience is integrated with a teaching program which includes a How to Teach course, instruction in classroom technology and course development and mentored teaching. During their mentored teaching experiences, fellows are encouraged to explore innovative teaching methodologies and to perform science teaching research to improve classroom learning. FIRST fellows teaching neuroscience to undergraduates have observed that many of these students have difficulty with the topic of neuroscience. Therefore, we investigated the effects of interactive teaching methods for this topic. We tested two interactive teaching methodologies to determine if they would improve learning and retention of this information when compared with standard lectures. The interactive methods for teaching action potentials increased understanding and retention. Therefore, FIRST provides excellent teaching training, partly by enhancing the ability of fellows to integrate innovative teaching methods into their instruction. This training in turn provides fellows that matriculate from this program more of the characteristics that hiring institutions desire in their new faculty
Producción, consumo de información e impacto de la Revista de Arquitectura (Bogotá). Análisis bibliométrico 2016-2019
La arquitectura tiene un amplio campo de acción disciplinar que abarca las ciencias sociales, el arte y las humanidades, y la ingeniería, por lo cual se busca caracterizar las prácticas de producción editorial, consumo de información e impacto presentes en la Revista de Arquitectura (Bogotá). Para lograr esto se realizó un estudio de carácter descriptivo y retrospectivo, a partir de indicadores bibliométricos, tomado artículos originales, revisados por pares y publicados en las tres secciones principales. Como resultado de esto, se identificó un publicación constante y homogénea en las tres secciones, pero con diferencias en la dinámica de producción y consumo de información siendo en la sección TMS donde hay mayor número de referencias bibliográficas y un mejor índice Price, también se destaca el uso de revistas y de literatura en inglés. En la sección CUE, se observó concentración de la literatura en español, y un equilibro entre las fechas de las referencias cada cinco años. Para el caso de PAU, se observó mayor internacionalización y una preferencia por el libro y uso de referencias de fechas de 15 o más años. A nivel general se observó un impacto positivo por citación y métricas alternativas
The Research Excellence Framework (REF): Assessing the impact of social work research on society
This paper reviews one aspect, impact, of the forthcoming assessment of research in UK universities, the Research Excellence Framework (REF), and examines its meaning and potential for enhanced partnerships between social work practice and academia in the context of the current economic crisis. Examples of case studies being developed to show how research has societal impact are described and some of the complexities of what, on the surface appears to echo social work 19s desire to make a positive difference to the lives of people in society, are drawn out. The importance of the REF for the integration of social work practice and academia have been rehearsed many times. This paper argues that making an impact is everybody 19s concern and practitioners and those who use social work services and their carers have a role to play in its creation and identification
Radiation of Neutron Stars Produced by Superfluid Core
We find that neutron star interior is transparent for collisionless electron
sound, the same way as it is transparent for neutrinos. In the presence of
magnetic field the electron sound is coupled with electromagnetic radiation and
form the fast magnetosonic wave. We find that electron sound is generated by
superfluid vortices in the stellar core. Thermally excited helical vortex waves
produce fast magnetosonic waves in the stellar crust which propagate toward the
surface and transform into outgoing electromagnetic radiation. The vortex
radiation has the spectral index -0.45 and can explain nonthermal radiation of
middle-aged pulsars observed in the infrared, optical and hard X-ray bands. The
radiation is produced in the stellar interior which allows direct determination
of the core temperature. Comparing the theory with available spectra
observations we find that the core temperature of the Vela pulsar is T=8*10^8K,
while the core temperature of PSR B0656+14 and Geminga exceeds 2*10^8K. This is
the first measurement of the temperature of a neutron star core. The
temperature estimate rules out equation of states incorporating Bose
condensations of pions or kaons and quark matter in these objects. Based on the
temperature estimate and cooling models we determine the critical temperature
of triplet neutron superfluidity in the Vela core Tc=(7.5\pm 1.5)*10^9K which
agrees well with recent data on behavior of nucleon interactions at high
energies. Another finding is that in the middle aged neutron stars the vortex
radiation, rather then thermal conductivity, is the main mechanism of heat
transfer from the stellar core to the surface. Electron sound opens a
perspective of direct spectroscopic study of superdense matter in the neutron
star interiors.Comment: 43 pages, 7 figures, to appear in Astrophysical Journa
Panoramic Views of the Cygnus Loop
We present a complete atlas of the Cygnus Loop supernova remnant in the light
of [O III] (5007), H alpha, and [S II] (6717, 6731). Despite its shell-like
appearance, the Cygnus Loop is not a current example of a Sedov-Taylor blast
wave. Rather, the optical emission traces interactions of the supernova blast
wave with clumps of gas. The surrounding interstellar medium forms the walls of
a cavity through which the blast wave now propagates, including a nearly
complete shell in which non-radiative filaments are detected. The Cygnus Loop
blast wave is not breaking out of a dense cloud, but is instead running into
confining walls. The interstellar medium dominates not only the appearance of
the Cygnus Loop but also the continued evolution of the blast wave. If this is
a typical example of a supernova remnant, then global models of the
interstellar medium must account for such significant blast wave deceleration.Comment: 28 pages AAS Latex, 28 black+white figures, 6 color figures. To be
published in The Astrophysical Journal Supplement Serie
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