1,326 research outputs found
Relationship with theory:A study exploring the impact of theory on the way trainee counselling psychologists make sense of their emotional responses to clients in practice
A Capability Maturity Model to assess Government ICT4D Policy
The efforts of a Government to provide ICTs in a developing country are mostly well intended but not always successful. To establish why this happens can be a complex process. Influencing government initiatives are a variety of inhibitors, enablers and influences ranging from the diversity of stakeholders and their cultures and history, to skill levels, existing infrastructure, economic conditions, access, prejudice and politics, and language. All these factors need to be understood and managed before current or future initiatives can hope to be successful. To this end, the purpose of this paper was to develop a Capability Maturity Model for use as a conceptual framework to advance the understanding of researchers and practitioners of Governmental ICT4D policy, and the implementation of that policy. This paper sets up a theoretical model with four levels of maturity, each level consisting of five dimensions. Each of the five dimensions are then discussed and, finally, the use and contribution of the model is outlined
Magnetic field effects on the density of states of orthorhombic superconductors
The quasiparticle density of states in a two-dimensional d-wave
superconductor depends on the orientation of the in-plane external magnetic
field H. This is because. in the region of the gap nodes, the Doppler shift due
to the circulating supercurrents around a vortex depend on the direction of H.
For a tetragonal system the induced pattern is four-fold symmetric and, at zero
energy, the density of states exhibits minima along the node directions. But
YBa_2C_3O_{6.95} is orthorhombic because of the chains and the pattern becomes
two-fold symmetric with the position of the minima occuring when H is oriented
along the Fermi velocity at a node on the Fermi surface. The effect of impurity
scattering in the Born and unitary limit is discussed.Comment: 24 pages, 11 Figure
Design and Testing of a Novel Air-cooled Condenser for Concentrated Solar Power Plants
AbstractThis paper aims at developing a novel air-cooled condenser for concentrated solar power plants. The condenser offers two significant advantages over the existing state of the art. Firstly, it can be installed in a modular format where pre-assembled condenser modules reduce installation costs. Secondly, instead of using large, fixed speed fans, smaller speed controlled fans are incorporated into the individual modules. This facility allows the operating point of the condenser to change in order to maximise plant efficiency at all times. Two condenser designs were proposed and full-scale prototype modules were manufactured for experimental testing. Both designs comprise a bank of circular finned tubes, coupled to an array of axial fans. The air-side thermal and aerodynamic characteristics were measured using a purpose built steady-state test facility. The measurements were correlated and compared well with existing correlations in the relevant literature, thus validating their use in thermodynamic models to predict power plant performance. A plant performance analysis was conducted combing the experimental measurements with output data from a 50MW concentrated solar power plant. This analysis firstly verified that the plant efficiency can be continually maximised by altering the condenser fan speed. Furthermore, under certain conditions plant output can be increased by over 10% by varying fan speed by 10% of the full speed. The study also provides a comparison of the two designs in terms of their effect on the plant output power. With respect to the thermodynamic efficiency and cost-efficiency, the four row condenser substantially outperforms the initial six row design
The Broadband Infrared Emission Spectrum of the Exoplanet TrES-3
We use the Spitzer Space Telescope to estimate the dayside thermal emission
of the exoplanet TrES-3 integrated in the 3.6, 4.5, 5.8, and 8.0 micron
bandpasses of the Infrared Array Camera (IRAC) instrument. We observe two
secondary eclipses and find relative eclipse depths of 0.00346 +/- 0.00035,
0.00372 +/- 0.00054, 0.00449 +/- 0.00097, and 0.00475 +/- 0.00046, respectively
in the 4 IRAC bandpasses. We combine our results with the earlier K band
measurement of De Mooij et al. (2009), and compare them with models of the
planetary emission. We find that the planet does not require the presence of an
inversion layer in the high atmosphere. This is the first very strongly
irradiated planet that does not have a temperature inversion, which indicates
that stellar or planetary characteristics other than temperature have an
important impact on temperature inversion. De Mooij & Snellen (2009) also
detected a possible slight offset in the timing of the secondary eclipse in K
band. However, based on our 4 Spitzer channels, we place a 3sigma upper limit
of |ecos(w)| < 0.0056 where e is the planets orbital eccentricity and w is the
longitude of the periastron. This result strongly indicates that the orbit is
circular, as expected from tidal circularization theory.Comment: Accepted by Ap
Detection of transit timing variations in excess of one hour in the Kepler multi-planet candidate system KOI 806 with the GTC
We report the detection of transit timing variations (TTVs) well in excess of
one hour in the Kepler multi-planet candidate system KOI 806. This system
exhibits transits consistent with three separate planets -- a Super-Earth, a
Jupiter, and a Saturn -- lying very nearly in a 1:2:5 resonance, respectively.
We used the Kepler public data archive and observations with the Gran
Telescopio de Canarias to compile the necessary photometry. For the largest
candidate planet (KOI 806.02) in this system, we detected a large transit
timing variation of -103.56.9 minutes against previously published
ephemeris. We did not obtain a strong detection of a transit color signature
consistent with a planet-sized object; however, we did not detect a color
difference in transit depth, either. The large TTV is consistent with
theoretical predictions that exoplanets in resonance can produce large transit
timing variations, particularly if the orbits are eccentric. The presence of
large TTVs among the bodies in this systems indicates that KOI806 is very
likely to be a planetary system. This is supported by the lack of a strong
color dependence in the transit depth, which would suggest a blended eclipsing
binary.Comment: 9 pages, 4 figures, accepted into A&A Letter
Fermi-Liquid Interactions in d-Wave Superconductor
This article develops a quantitative quasiparticle model of the
low-temperature properties of d-wave superconductors which incorporates both
Fermi-liquid effects and band-structure effects. The Fermi-liquid interaction
effects are found to be classifiable into strong and negligible renormalizaton
effects, for symmetric and antisymmetric combinations of the energies of
and quasiparticles, respectively. A particularly
important conclusion is that the leading clean-limit temperature-dependent
correction to the superfluid density is not renormalized by Fermi-liquid
interactions, but is subject to a Fermi velocity (or mass) renormalization
effect. This leads to difficulties in accounting for the penetration depth
measurements with physically acceptable parameters, and hence reopens the
question of the quantitative validity of the quasiparticle picture.Comment: 4 page
The Challenge of Wide-Field Transit Surveys: The Case of GSC 01944-02289
Wide-field searches for transiting extra-solar giant planets face the
difficult challenge of separating true transit events from the numerous false
positives caused by isolated or blended eclipsing binary systems. We describe
here the investigation of GSC 01944-02289, a very promising candidate for a
transiting brown dwarf detected by the Transatlantic Exoplanet Survey (TrES)
network. The photometry and radial velocity observations suggested that the
candidate was an object of substellar mass in orbit around an F star. However,
careful analysis of the spectral line shapes revealed a pattern of variations
consistent with the presence of another star whose motion produced the
asymmetries observed in the spectral lines of the brightest star. Detailed
simulations of blend models composed of an eclipsing binary plus a third star
diluting the eclipses were compared with the observed light curve and used to
derive the properties of the three components. Our photometric and
spectroscopic observations are fully consistent with a blend model of a
hierarchical triple system composed of an eclipsing binary with G0V and M3V
components in orbit around a slightly evolved F5 dwarf. We believe that this
investigation will be helpful to other groups pursuing wide-field transit
searches as this type of false detection could be more common than true
transiting planets, and difficult to identify.Comment: To appear in ApJ, v. 621, 2005 March 1
- …