622 research outputs found
Young people’s experiences of fashion modelling: An exploratory phenomenological study
Research about fashion modelling within Psychology remains sparse. Rare empirical studies which do exist exhibit a tendency to pathologise models, and provide only a superficial insight into this career. Little is known about who a fashion model really is, what a young person who models experiences in their careers, or how they make sense of this role. With this in mind, the current study sought to explore the lived experience of young people who are fashion models. Three participants offered experiential accounts of modelling in the fashion industry, and Interpretative Phenomenological Analysis (IPA) revealed superordinate themes: ‘Growth and Development’, ‘Changes in Self-Perception’, and ‘A Job? Or a Way of Life?’. Change was found to be an integral part of the participants’ experiences, which led to both positive and negative developmental outcomes, including a self-reported growth in confidence and maturity, yet a potentially more self-critical view of one’s appearance. The role seemed to be an all-encompassing lifestyle rather than a job, and it is argued that modelling at a young age may act as a catalyst for a transition into adulthood. This study is exploratory in nature but provides an initial insight into the experiences of fashion modelling. The discussion identifies ways in which cognate sub-disciplines of Psychology may contribute to this area of research, thus developing and extending further the Psychological literature base in the field of fashion studies
Instabilities in the two-dimensional cubic nonlinear Schrodinger equation
The two-dimensional cubic nonlinear Schrodinger equation (NLS) can be used as
a model of phenomena in physical systems ranging from waves on deep water to
pulses in optical fibers. In this paper, we establish that every
one-dimensional traveling wave solution of NLS with trivial phase is unstable
with respect to some infinitesimal perturbation with two-dimensional structure.
If the coefficients of the linear dispersion terms have the same sign then the
only unstable perturbations have transverse wavelength longer than a
well-defined cut-off. If the coefficients of the linear dispersion terms have
opposite signs, then there is no such cut-off and as the wavelength decreases,
the maximum growth rate approaches a well-defined limit.Comment: 4 pages, 4 figure
Convergence to equilibrium for the discrete coagulation-fragmentation equations with detailed balance
Under the condition of detailed balance and some additional restrictions on
the size of the coefficients, we identify the equilibrium distribution to which
solutions of the discrete coagulation-fragmentation system of equations
converge for large times, thus showing that there is a critical mass which
marks a change in the behavior of the solutions. This was previously known only
for particular cases as the generalized Becker-D\"oring equations. Our proof is
based on an inequality between the entropy and the entropy production which
also gives some information on the rate of convergence to equilibrium for
solutions under the critical mass.Comment: 28 page
Diffusion quantum Monte Carlo study of three-dimensional Wigner crystals
We report diffusion quantum Monte Carlo calculations of three-dimensional
Wigner crystals in the density range r_s=100-150. We have tested different
types of orbital for use in the approximate wave functions but none improve
upon the simple Gaussian form. The Gaussian exponents are optimized by directly
minimizing the diffusion quantum Monte Carlo energy. We have carefully
investigated and sought to minimize the potential biases in our Monte Carlo
results. We conclude that the uniform electron gas undergoes a transition from
a ferromagnetic fluid to a body-centered-cubic Wigner crystal at r_s=106+/-1.
The diffusion quantum Monte Carlo results are compared with those from
Hartree-Fock and Hartree theory in order to understand the role played by
exchange and correlation in Wigner crystals. We also study "floating" Wigner
crystals and give results for their pair-correlation functions
Astrophysical constraints on primordial black holes in Brans-Dicke theory
We consider cosmological evolution in Brans-Dicke theory with a population of
primordial black holes. Hawking radiation from the primordial black holes
impacts various astrophysical processes during the evolution of the Universe.
The accretion of radiation by the black holes in the radiation dominated era
may be effective in imparting them a longer lifetime. We present a detailed
study of how this affects various standard astrophysical constraints coming
from the evaporation of primordial black holes. We analyze constraints from the
present density of the Universe, the present photon spectrum, the distortion of
the cosmic microwave background spectrum and also from processes affecting
light element abundances after nucleosynthesis. We find that the constraints on
the initial primordial black hole mass fractions are tightened with increased
accretion efficiency.Comment: 15 page
Primordial black holes in braneworld cosmologies: astrophysical constraints
In two recent papers we explored the modifications to primordial black hole
physics when one moves to the simplest braneworld model, Randall--Sundrum type
II. Both the evaporation law and the cosmological evolution of the population
can be modified, and additionally accretion of energy from the background can
be dominant over evaporation at high energies. In this paper we present a
detailed study of how this impacts upon various astrophysical constraints,
analyzing constraints from the present density, from the present high-energy
photon background radiation, from distortion of the microwave background
spectrum, and from processes affecting light element abundances both during and
after nucleosynthesis. Typically, the constraints on the formation rate of
primordial black holes weaken as compared to the standard cosmology if black
hole accretion is unimportant at high energies, but can be strengthened in the
case of efficient accretion.Comment: 17 pages RevTeX4 file with three figures incorporated; final paper in
series astro-ph/0205149 and astro-ph/0208299. Minor changes to match version
accepted by Physical Review
Hawking radiation of nonsingular black holes in two dimensions
In this letter we study the process of Hawking radiation of a black hole
assuming the existence of a limiting physical curvature scale. The particular
model is constructed using the Limiting Curvature Hypothesis (LCH) and in the
context of two-dimensional dilaton gravity. The black hole solution exhibits
properties of the standard Schwarzschild solution at large values of the radial
coordinate. However, near the center, the black hole is nonsingular and the
metric becomes that of de Sitter spacetime. The Hawking temperature is
calculated using the method of complex paths. We find that such black holes
radiate eternally and never completely evaporate. The final state is an
eternally radiating relic, near the fundamental scale, which should make a
viable dark matter candidate. We briefly comment on the black hole information
loss problem and the production of such black holes in collider experiments.Comment: 8 pages, 4 figures; minor revisions; references added; version to
appear in JHE
Demkov-Kunike model for cold atom association: weak interaction regime
We study the nonlinear mean-field dynamics of molecule formation at coherent
photo- and magneto-association of an atomic Bose-Einstein condensate for the
case when the external field configuration is defined by the quasi-linear level
crossing Demkov-Kunike model, characterized by a bell-shaped pulse and finite
variation of the detuning. We present a general approach to construct an
approximation describing the temporal dynamics of the molecule formation in the
weak interaction regime and apply the developed method to the nonlinear
Demkov-Kunike problem. The presented approximation, written as a scaled
solution to the linear problem associated to the nonlinear one we treat,
contains fitting parameters which are determined through a variational
procedure. Assuming that the parameters involved in the solution of the linear
problem are not modified, we suggest an analytical expression for the scaling
parameter.Comment: 6 pages, 4 figure
Constraints on diffuse neutrino background from primordial black holes
We calculated the energy spectra and the fluxes of electron neutrino emitted
in the process of evaporation of primordial black holes (PBHs) in the early
universe. It was assumed that PBHs are formed by a blue power-law spectrum of
primordial density fluctuations. We obtained the bounds on the spectral index
of density fluctuations assuming validity of the standard picture of
gravitational collapse and using the available data of several experiments with
atmospheric and solar neutrinos. The comparison of our results with the
previous constraints (which had been obtained using diffuse photon background
data) shows that such bounds are quite sensitive to an assumed form of the
initial PBH mass function.Comment: 18 pages,(with 7 figures
Faddeev calculations for the A=5,6 Lambda-Lambda hypernuclei
Faddev calculations are reported for Lambda-Lambda-5H, Lambda-Lambda-5He and
Lambda-Lambda-6He in terms of two Lambda hyperons plus the respective nuclear
clusters, using Lambda-Lambda central potentials considered in past non-Faddeev
calculations of Lambda-Lambda-6He. The convergence with respect to the
partial-wave expansion is studied, and comparison is made with some of these
Lambda-Lambda hypernuclear calculations. The Lambda-Lambda Xi-N mixing
effect is briefly discussed.Comment: submitted for publicatio
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