67,761 research outputs found
MHD Disc Winds and Linewidth Distributions
We study AGN emission line profiles combining an improved version of the
accretion disc-wind model of Murray & Chiang with the magneto-hydrodynamic
model of Emmering et al. We show how the shape, broadening and shift of the C
IV line depend not only on the viewing angle to the object but also on the wind
launching angle, especially for small launching angles. We have compared the
dispersions in our model C IV linewidth distributions to observational upper
limit on that dispersion, considering both smooth and clumpy torus models. As
the torus half-opening angle (measured from the polar axis) increases above
about 18? degrees, increasingly larger wind launching angles are required to
match the observational constraints. Above a half-opening angle of about 47?
degrees, no wind launch angle (within the maximum allowed by the MHD solutions)
can match the observations. Considering a model that replaces the torus by a
warped disc yields the same constraints obtained with the two other models
Condensate splitting in an asymmetric double well for atom chip based sensors
We report on the adiabatic splitting of a BEC of Rb atoms by an
asymmetric double-well potential located above the edge of a perpendicularly
magnetized TbGdFeCo film atom chip. By controlling the barrier height and
double-well asymmetry the sensitivity of the axial splitting process is
investigated through observation of the fractional atom distribution between
the left and right wells. This process constitutes a novel sensor for which we
infer a single shot sensitivity to gravity fields of . From a simple analytic model we propose improvements
to chip-based gravity detectors using this demonstrated methodology.Comment: 4 pages, 5 figure
Pupil participation in Scottish schools: final report
This research was commissioned by Learning and Teaching Scotland (LTS) to evaluate the nature of pupil participation in primary and secondary schools across Scotland. The specific objectives of the research were:
<p>· To describe what school staff and pupils understand by the term ‘pupil participation’.</p>
<p>· To describe the range and usage of pupil participation mechanisms employed in schools.</p>
<p>· To describe how school staff respect and respond to pupils’ views and ideas, and those of the wider community.</p>
<p>· To identify the characteristics of schools and classrooms that facilitate effective pupil participation.</p>
<p>· To identify possible barriers to the development of pupil participation in schools and to make suggestions about how these can be overcome.</p>
<p>· To capture examples of effective practice of pupil participation.</p>
<p>· To make suggestions about how pupil participation can help support the implementation of the Curriculum for Excellence.</p>
Surface roughness detector Patent
Roughness detector for recording surface pattern of irregularitie
APPLICATION OF A DYNAMIC PANEL DATA ESTIMATOR TO CROSS-COUNTRY COFFEE DEMAND: A TALE OF TWO ERAS
We estimate price and income elasticities of demand for green coffee beans in panels of up to 40 countries, both during and after the operation of export quotas under International Coffee Agreements. The dynamic panel estimator proposed in Han and Phillips (2007) is used because it is a consistent estimator, for any length of panel, regardless of the presence of unit roots. Dynamic panel data models, of any type, do not seem to have been previously applied to coffee demand. We find evidence of a concave relationship between income and coffee consumption for countries which are members of the International Coffee Organization, but no evidence of such a relationship for other countries. A further conclusion is that measures which increase the price of coffee beans can be expected to have little effect on coffee sales.Coffee Demand, Dynamic Panel Data, International Coffee Organization
2MASS 1315-2649: A High Proper Motion L Dwarf with Strong H-alpha Emission
In Hall (2002) I reported that 2MASSI J1315309-264951 is an L dwarf with
strong H-alpha emission. Two spectroscopic epochs appeared to show that the
H-alpha was variable, decreasing from 121 Angstroms to 25 Angstroms EW, which I
interpreted as a flare during the first observation. Gizis (2002) independently
discovered this object, and his intermediate spectroscopic epoch shows H-alpha
with 97 Angstroms EW. A new fourth epoch of spectroscopy again shows a very
large H-alpha EW (124 Angstroms), confirming this object to be a persistent,
strong H-alpha emitter. Whether the H-alpha is steady (like 2MASS 1237+6526) or
from continuous strong flaring (like PC0025+0447) remains unclear. Imaging
confirms that 2MASS 1315-2649 has a high proper motion (0.71"/year),
corresponding to a transverse velocity of ~76 km/s at its distance of ~23 pc.
Thus 2MASS 1315-2649 is consistent with being >~2 Gyr old and therefore
relatively massive. If that is so, the correlation of H-alph activity with mass
found by Gizis et al. (2000) would seem to support the continuous strong
flaring scenario, though it does not rule out a brown dwarf binary accretion
scenario.Comment: 2 pages, ApJL accepte
Pupil participation in Scottish schools: how far have we come?
The United Nations Convention on the Rights of the Child (UN, 1989), which applies to all children under the age of 18, established the overarching principles guiding pupil participation. In most European states, signatories to the Convention have enacted policies to promote the voice of the child or young person in decisions that affect them. In education systems strategies to enhance the pupil participation are an increasing feature of deliberation on education for citizenship, curriculum flexibility, pedagogical approaches and assessment for learning. Despite the positive policy context and professional commitment to principles of inclusion, translating policy intentions so that the spirit of the legislation is played out in the day-to-day experiences of pupils is a constant challenge. This article reports on research that examines how pupil participation is understood and enacted in Scottish schools. It considers how the over-laying of diverse policies presents mixed messages to practitioners
Self-similar static solutions admitting a two-space of constant curvature
A recent result by Haggag and Hajj-Boutros is reviewed within the framework
of self-similar space-times, extending, in some sense, their results and
presenting a family of metrics consisting of all the static spherically
symmetric perfect fluid solutions admitting a homothety.Comment: 6 page
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