520 research outputs found
Phase Transitions and Critical Behavior for Charged Black Holes
We investigate the thermodynamics of a four-dimensional charged black hole in
a finite cavity in asymptotically flat and asymptotically de Sitter space. In
each case, we find a Hawking-Page-like phase transition between a black hole
and a thermal gas very much like the known transition in asymptotically anti-de
Sitter space. For a ``supercooled'' black hole--a thermodynamically unstable
black hole below the critical temperature for the Hawking-Page phase
transition--the phase diagram has a line of first-order phase transitions that
terminates in a second order point. For the asymptotically flat case, we
calculate the critical exponents at the second order phase transition and find
that they exactly match the known results for a charged black hole in anti-de
Sitter space. We find strong evidence for similar phase transitions for the de
Sitter black hole as well. Thus many of the thermodynamic features of charged
anti-de Sitter black holes do not really depend on asymptotically anti-de
Sitter boundary conditions; the thermodynamics of charged black holes is
surprisingly universal.Comment: LaTeX, 14 pages, 9 eps figures; higher resolution figures available
on reques
Dark Matter at the Center and in the Halo of the Galaxy
All presently known stellar-dynamical constraints on the size and mass of the
supermassive compact dark object at the Galactic center are consistent with a
ball of self-gravitating, nearly non-interacting, degenerate fermions with mass
between 76 and 491 keV, for degeneracy factor g=2. Sterile neutrinos of 76 keV
mass, which are mixed with at least one of the active neutrinos with a mixing
angele ~10^{-7}, are produced in about the right amount in the early Universe
by incoherent resonant and non-resonant scattering of active neutrinos having
asymmetry of ~0.01. The former process yields sterile neutrinos with a
quasi-degenerate spectrum while the latter leads to a thermal spectrum. As the
production mechanism of the sterile neutrino is consistent with the constraints
from large scale structure formation, core collapse supernovae, and diffuse
X-ray background, it could be the dark matter particle of the Universe.Comment: 6 pages, to appear in the Beyond 2003 conference proceeding
From fused aromatics to graphene-like nanoribbons: The effects of multiple terminal groups, length and symmetric pathways on charge transport
class of molecular ribbons, with almost-ideal charge transmission, that is weakly dependent on the anchoring structure or electrode crystalline orientation and easy to synthesize has been identified. Charge transport through two sets of aromatic nanoribbons, based on the pyrene and perylene motifs, has been investigated using density functional theory combined with the nonequilibrium Green's function method. The effects of wire length and multiple terminal thiolate groups at the junction with gold leads have been examined. For the oligopyrene series, an exponential drop in the conductance with the increase of the wire length is found. In contrast, the oligoperylene series of nanoribbons, with dual thiolate groups, exhibits no visible length dependence, indicating that the contacts are the principal source of the resistance. Between the Au(001) leads, the transmission spectra of the oligoperylenes display a continuum of highly conducting channels and the resulting conductance is nearly independent of the bias. The predictions are robust against artefacts from the exchange-correlation potential, as evidenced from the self-interaction corrected calculations. Therefore, oligoperylene nanoribbons show the potential to be the almost-ideal wires for molecular circuitry
Academic integrity: An educative and equitable approach in enabling pathway programs
This paper unpacks the key components of an educative approach to academic integrity and applies them to enabling pathway programs. Enabling programs progress high numbers of students from recognised equity groups into undergraduate studies and are recognised for supporting and encouraging students and fostering a sense of belonging (Burke, Bennett, Burgess, Gray, & Southgate, 2016; Hellmundt & Baker, 2017; Lane & Sharp, 2014). University measures to support academic integrity can, on the other hand, be perceived as procedure-based and punitive (Dalal, 2015). In this paper, we provide an integrative review of literature on the common features of an educative approach to academic integrity and enabling programs and introduce exemplars from two universities of enabling pedagogies applied to academic integrity
Empirical Analyses of the Relationship between Trade and Budget Deficit of FYR of Macedonia
The purpose of this article is to analyze the evidence of twin deficits hypothesis by empirically examining the relationship between trade deficit and budget deficit for the case of FYR of Macedonia. The study employs a vector autoregression (VAR) model as well as a Granger causality test in order to investigate the causal relationship between trade and budget deficit variables using quarterly data for the time period 1998Q1–2017Q4. The econometric results of VAR model disclose that there exists a short term relationship between these two variables, implying that higher trade deficits are associated with higher fiscal deficits. Moreover, the causality test shows a unidirectional relationship, revealing that trade deficit causes budget deficit, whereas budget deficit doesn't cause trade deficit.
Keywords: trade deficit, budget deficit, causality analysi
Does an educative approach work? A reflective case study of how two Australian higher education Enabling programs support students and staff uphold a responsible culture of academic integrity
Introduction
Enabling education programs, otherwise known as Foundation Studies or Preparatory programs, provide pathways for students typically under-represented in higher education. Students in Enabling programs often face distinct challenges in their induction to academic culture which can implicate them in cases of misconduct. This case study addresses a gap in the enabling literature reporting on how a culture of academic integrity can be developed for students and staff in these programs through an educative approach.
Case description
This paper outlines how an educative approach to academic integrity is implemented within the Enabling programs of two Australian universities.
Discussion and reflection
This case study reflects upon an approach which makes specific reference to the key elements of ‘support’, ‘approach’ and ‘responsibility’ as highlighted in Bretag and Mahmud’s seminal paper. The paper reports a reduction in misconduct cases at the two institutions suggesting a positive correlation between the interventions and students’ understanding of ethical academic practice. This study reflects upon practitioner experiences with academic integrity investigations to evaluate the effectiveness of this approach.
Conclusions
The authors show that it is possible to ensure academic integrity practices and values are upheld within a supportive learning environment appropriate to a students’ level of study
Constant-roll inflation with tachyon field in the holographic braneworld
We study inflation driven by the tachyon field in the holographic braneworld
by assuming the second slow-roll parameter is constant. The parameter
can be either defined by the tachyon scalar field and the Hubble
parameter or by the Hubble parameter only. By assuming a constant , we
derive and numerically solve a differential equation for the Hubble expansion
rate. We calculate numerically the scalar spectral index and the
tensor-to-scalar ratio. We confront the results with the observational data and
find some constraints on the free model parameters. The swampland conjectures
are discussed in the context of the constant-roll inflation, with some accent
on the holographic model
Tachyon constant-roll inflation in Randall-Sundrum II cosmology
We study inflation in a model with constant second slow-roll parameter
. In this case, the Hubble expansion rate equation has analytical
solutions describing four possible, nontrivial inflation scenarios. The
evolution of the inflaton governed by a tachyon field is studied in the
framework of the standard and Randall-Sundrum II cosmology. The attractor
behavior of the solution is briefly demonstrated. Finally, the calculated
values of the parameters and are compared with observational
data
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