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Addressing the needs of international postgraduate students: the role of social capital
Self-evidently, international students are likely to have considerable informational and social needs when coming to study in the UK. This paper reports the findings of a small study of such needs among international postgraduate students in the School of Health Sciences. It was an interview study, with twelve students participating. Though the study was designed to support the creation of an online resource, the findings suggest that meeting those needs satisfactorily requires a multi-faceted approach. Both face-to-face and online processes are needed to help students to develop the social capital necessary to success in undertaking the course, getting to know the university, and adjusting to life in England
Optical Dielectric Functions of III-V Semiconductors in Wurtzite Phase
Optical properties of semiconductors can exhibit strong polarization
dependence due to crystalline anisotropy. A number of recent experiments have
shown that the photoluminescence intensity in free standing nanowires is
polarization dependent. One contribution to this effect is the anisotropy of
the dielectric function due to the fact that most nanowires crystalize in the
wurtzite form. While little is known experimentally about the band structures
wurtzite phase III-V semiconductors, we have previously predicted the bulk band
structure of nine III-V semiconductors in wurtzite phase.Here, we predict the
frequency dependent dielectric functions for nine non-Nitride wurtzite phase
III-V semiconductors (AlP, AlAs, AlSb, GaP, GaAs, GaSb, InP, InAs and InSb).
Their complex dielectric functions are calculated in the dipole approximation
by evaluating the momentum matrix elements on a dense grid of special k-points
using empirical pseudopotential wave functions. Corrections to the momentum
matrix elements accounting for the missing core states are made using a scaling
factor which is determined by using the optical sum rules on the calculated
dielectric functions for the zincblende polytypes. The dielectric function is
calculated for polarizations perpendicular and parallel to the c-axis of the
crystal
Effect of time delay on feedback control of a flashing ratchet
It was recently shown that the use of feedback control can improve the
performance of a flashing ratchet. We investigate the effect of a time delay in
the implementation of feedback control in a closed-loop collective flashing
ratchet, using Langevin dynamics simulations. Surprisingly, for a large
ensemble, a well-chosen delay time improves the ratchet performance by allowing
the system to synchronize into a quasi-periodic stable mode of oscillation that
reproduces the optimal average velocity for a periodically flashing ratchet.
For a small ensemble, on the other hand, finite delay times significantly
reduce the benefit of feedback control for the time-averaged velocity, because
the relevance of information decays on a time scale set by the diffusion time
of the particles. Based on these results, we establish that experimental use of
feedback control is realistic.Comment: 6 pages, 6 figures, to appear in Europhysics Letter
Asymptotic stabilization of Euler-Poincaré mechanical systems
Stabilization of mechanical control systems by the method of controlled Lagrangians
and matching is used to analyze asymptotic stabilization of systems whose
underlying dynamics are governed by the Euler-Poincar´e equations. In particular, we
analyze asymptotic stabilization of a satellite
An adaptive controller for enhancing operator performance during teleoperation
An adaptive controller is developed for adjusting robot arm parameters while manipulating payloads of unknown mass and inertia. The controller is tested experimentally in a master/slave configuration where the adaptive slave arm is commanded via human operator inputs from a master. Kinematically similar six-joint master and slave arms are used with the last three joints locked for simplification. After a brief initial adaptation period for the unloaded arm, the slave arm retrieves different size payloads and maneuvers them about the workspace. Comparisons are then drawn with similar tasks where the adaptation is turned off. Several simplifications of the controller dynamics are also addressed and experimentally verified
What did Aspiring Young Entrepreneurs in Nicaragua Recognize as Agribusiness and Ecotourism Opportunities using Photovoice as a Data Collection Tool?
Interest in entrepreneurship education by scholars and practitioners as a way to overcome poverty is growing. Yet little is known about how entrepreneurship can be a successful approach to achieving prosperity in resource-poor conditions. Entrepreneurship has been mainly associated with the view of entrepreneurs as super humans capable of solving all problems, especially if operating in resource-rich contexts. This qualitative study’s purpose was to explore, through photovoice methodology, the entrepreneurial opportunities involving agribusiness and ecotourism that Nicaraguan students recognized in their communities. Photovoice allowed the researchers to gain in-depth information from students who expressed in images what may have been difficult to explain in words. The students recognized different opportunities linked to their contexts as expressed through photos documenting local assets and materials. The study participants also indicated interests in doing social good, which suggested a more societally oriented view of entrepreneurship. The poor, including youth often marginalized, were able to recognize business opportunities in concert with their economic conditions. Opportunity recognition may be one of the more promising ways to overcome poverty. Its facilitation holds implications for agricultural, tourism, and rural development curricula and educational programming
New remarks on the Cosmological Argument
We present a formal analysis of the Cosmological Argument in its two main
forms: that due to Aquinas, and the revised version of the Kalam Cosmological
Argument more recently advocated by William Lane Craig. We formulate these two
arguments in such a way that each conclusion follows in first-order logic from
the corresponding assumptions. Our analysis shows that the conclusion which
follows for Aquinas is considerably weaker than what his aims demand. With
formalizations that are logically valid in hand, we reinterpret the natural
language versions of the premises and conclusions in terms of concepts of
causality consistent with (and used in) recent work in cosmology done by
physicists. In brief: the Kalam argument commits the fallacy of equivocation in
a way that seems beyond repair; two of the premises adopted by Aquinas seem
dubious when the terms `cause' and `causality' are interpreted in the context
of contemporary empirical science. Thus, while there are no problems with
whether the conclusions follow logically from their assumptions, the Kalam
argument is not viable, and the Aquinas argument does not imply a caused
origination of the universe. The assumptions of the latter are at best less
than obvious relative to recent work in the sciences. We conclude with mention
of a new argument that makes some positive modifications to an alternative
variation on Aquinas by Le Poidevin, which nonetheless seems rather weak.Comment: 12 pages, accepted for publication in International Journal for
Philosophy of Religio
Feedback-controlled transport in an interacting colloidal system
Based on dynamical density functional theory (DDFT) we consider a
non-equilibrium system of interacting colloidal particles driven by a constant
tilting force through a periodic, symmetric "washboard" potential. We
demonstrate that, despite of pronounced spatio-temporal correlations, the
particle current can be reversed by adding suitable feedback control terms to
the DDFT equation of motion. We explore two distinct control protocols with
time delay, focussing on either the particle positions or the density profile.
Our study shows that the DDFT is an appropriate framework to implement
time-delayed feedback control strategies widely used in other fields of
nonlinear physicsComment: 6 pages, 5 figure
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