495 research outputs found
Non-stationary rotating black holes: Entropy and Hawking's radiation
We derive a class of non-stationary embedded rotating black holes and study
the Hawking's radiation effects on these embedded black holes. The surface
gravity, entropy and angular velocity, which are three important properties of
black holes, are presented for each of these embedded black holes.Comment: 36 pages, LaTe
Scaling of the Fano effect of the in-plane Fe-As phonon and the superconducting critical temperature in BaKFeAs
By means of infrared spectroscopy we determine the temperature-doping phase
diagram of the Fano effect for the in-plane Fe-As stretching mode in
BaKFeAs. The Fano parameter , which is a
measure of the phonon coupling to the electronic particle-hole continuum, shows
a remarkable sensitivity to the magnetic/structural orderings at low
temperatures. More strikingly, at elevated temperatures in the
paramagnetic/tetragonal state we find a linear correlation between and
the superconducting critical temperature . Based on theoretical
calculations and symmetry considerations, we identify the relevant interband
transitions that are coupled to the Fe-As mode. In particular, we show that a
sizable orbital component at the Fermi level is fundamental for the Fano
effect and possibly also for the superconducting pairing.Comment: Supplemental materials are available upon reques
Psychology students’ perception of and engagement with feedback as a function of year of study
Undergraduate students’ perception of feedback and level of engagement with the feedback they receive have gained increasing attention in the educational literature recently to identify areas which require educators’ attention. However, research in this area has generally been based on limited self-selecting samples, and has not considered how students’ relationship with feedback may alter depending on their year of study. To address this, a survey measuring students’ views and practices regarding feedback was completed at a higher education institution by 447 first-, second- and third-year psychology students, representing 77% of the cohort. Findings revealed that third years responded more negatively in both areas than their first- and second-year counterparts, whose ratings on these aspects themselves were far from optimal. These findings highlight the need for early interventions to improve students’ perception of and engagement with feedback in the earlier years, and to prevent the recorded deterioration later on in the degree course
Transition from an electron solid to the sequence of fractional quantum Hall states at very low Landau level filling factor
At low Landau level filling of a two-dimensional electron system, typically
associated with the formation of an electron crystal, we observe local minima
in Rxx at filling factors nu=2/11, 3/17, 3/19, 2/13, 1/7, 2/15, 2/17, and 1/9.
Each of these developing fractional quantum Hall (FQHE) states appears only
above a filling factor-specific temperature. This can be interpreted as the
melting of an electron crystal and subsequent FQHE liquid formation. The
observed sequence of FQHE states follow the series of composite fermion states
emanating from nu=1/6 and nu=1/8
Inflating Lorentzian Wormholes
It has been speculated that Lorentzian wormholes of the Morris- Thorne type
might be allowed by the laws of physics at submicroscopic, e.g. Planck, scales
and that a sufficiently advanced civilization might be able to enlarge them to
classical size. The purpose of this paper is to explore the possibility that
inflation might provide a natural mechanism for the enlargement of such
wormholes to macroscopic size. A new classical metric is presented for a
Lorentzian wormhole which is imbedded in a flat deSitter space. It is shown
that the throat and proper length of the wormhole inflate. The resulting
properties and stress-energy tensor associated with this metric are discussed.Comment: 24 pg
Reflection and the art of coaching: fostering high-performance in olympic ski cross
In preparation for the 2010 Vancouver Winter Olympic Games, the lead author engaged in systematic reflection in an attempt to implement coaching behaviours and create practice environments that promoted athlete development (psycho-social and physical performance). The research was carried out in relation to his work as head Ski Cross coach working with (primarily) three athletes in their quest for Olympic qualification and subsequent performance success in the Olympic Games. This project sought to examine coach-athlete interactions. Of particular interest were coach and athlete responses regarding the implementation of autonomy supportive coaching behaviours in a high context. Autonomy supportive coaching behaviours have previously been strongly associated with positive athlete psycho-social and performance outcomes, however, a paucity of research has examined its implementation in high-performance contexts. Through the use of participant ethnography, it was possible to gain considerable insights regarding athletes' perceptions of choice, implications of perceived athletic hierarchies, as well as cultural and experience-related influences on training and performance expectations
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