21,666 research outputs found
The role of voice technology in advanced helicopter cockpits
The status of voice output and voice recognition technology in relation to helicopter cockpit applications is described. The maturing of this technology provides many opportunities for new approaches to crew workload reduction. The helicopter operating environment, potential application areas, and the impact on advanced cockpit design are discussed
Fractional Chern Insulators in Bands with Zero Berry Curvature
Even if a noninteracting system has zero Berry curvature everywhere in the
Brillouin zone, it is possible to introduce interactions that stabilise a
fractional Chern insulator. These interactions necessarily break time-reversal
symmetry (either spontaneously or explicitly) and have the effect of altering
the underlying band structure. We outline a number of ways in which this may be
achieved, and show how similar interactions may also be used to create a
(time-reversal symmetric) fractional topological insulator. While our approach
is rigorous in the limit of long range interactions, we show numerically that
even for short range interactions a fractional Chern insulator can be
stabilised in a band with zero Berry curvature.Comment: 7 pages, 2 figures; Published versio
Perturbative Approach to Flat Chern Bands in the Hofstadter Model
We present a perturbative approach to the study of the Hofstadter model for
when the amount of flux per plaquette is close to a rational fraction. Within
this approximation certain eigenstates of the system are shown to be
multi-component wavefunctions that connect smoothly to the Landau levels of the
continuum. The perturbative corrections to these are higher Landau level
contributions that break rotational invariance and allow the perturbed states
to adopt the symmetry of the lattice. In the presence of interactions, this
approach allows for the calculation of generalised Haldane pseudopotentials,
and in turn, the many-body properties of the system. The method is sufficiently
general that it can apply to a wide variety of lattices, interactions and
magnetic field strengths.Comment: 40 pages, 15 figures; v2 includes minor changes, additional
references and an expanded background sectio
How much are senior UK public health professionals taught about mental health?
Directors, consultants and specialists in public mental health play a major role in developing and implementing local and national mental health policy. This study focuses on what academic training they receive about mental health via Master of Public Health (MPH) programmes. If you are a clinical psychologist involved in teaching on a MPH course we would be interested in hearing about your experiences
They (Don't) Care About Education: A Counternarrative on Black Male Students' Responses to Inequitable Schooling
Focus group interviews and systematic content analysis of 304 essays written by black male undergraduates refute the dominant message that black men do not care about education. On the contrary, these students aspire to earn doctoral degrees in education despite acute understanding that the education system is stacked against them. The analysis asks what compels that dedication
Fluorine in the solar neighborhood - is it all produced in AGB-stars?
The origin of 'cosmic' fluorine is uncertain, but there are three proposed
production sites/mechanisms: AGB stars, nucleosynthesis in Type II
supernovae, and/or the winds of Wolf-Rayet stars. The relative importance of
these production sites has not been established even for the solar
neighborhood, leading to uncertainties in stellar evolution models of these
stars as well as uncertainties in the chemical evolution models of stellar
populations.
We determine the fluorine and oxygen abundances in seven bright, nearby
giants with well-determined stellar parameters. We use the 2.3 m
vibrational-rotational HF line and explore a pure rotational HF line at 12.2
m. The latter has never been used before for an abundance analysis. To be
able to do this we have calculated a line list for pure rotational HF lines. We
find that the abundances derived from the two diagnostics agree.
Our derived abundances are well reproduced by chemical evolution models only
including fluorine production in AGB-stars and therefore we draw the conclusion
that this might be the main production site of fluorine in the solar
neighborhood. Furthermore, we highlight the advantages of using the 12 m
HF lines to determine the possible contribution of the -process to the
fluorine budget at low metallicities where the difference between models
including and excluding this process is dramatic
Far-infrared observations of Sagittarius B2: Reconsideration of source structure
New moderate-angular-resolution far-infrared observations of the Sagittarius B2 star-forming region are presented, discussed, and compared with recent radio molecular and continuum observations of this source. In contrast to previous analyses, its far-infrared spectrum is interpreted as the result of a massive frigid cloud overlying a more-or-less normal infrared source, a natural explanation for the object's previously-noted pecularities. The characteristics derived for the obscuring cloud are similar to those found for the W51 MAIN object. Both sources have high sub-millimeter surface brightness, a high ratio of sub-millimeter to far-infrared flux, and numerous regions of molecular maser emission
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