5,141 research outputs found
Survey of curriculums in summer music camps and correlation with school music.
Thesis (M.M.)--Boston Universit
A class of exactly solvable models for the Schrodinger equation
We present a class of confining potentials which allow one to reduce the
one-dimensional Schroodinger equation to a named equation of mathematical
physics, namely either Bessel's or Whittaker's differential equation. In all
cases, we provide closed form expressions for both the symmetric and
antisymmetric wavefunction solutions, each along with an associated
transcendental equation for allowed eigenvalues. The class of potentials
considered contains an example of both cusp-like single wells and a
double-well.Comment: 5 pages, 7 figure
Localization of massless Dirac particles via spatial modulations of the Fermi velocity
The electrons found in Dirac materials are notorious for being difficult to
manipulate due to the Klein phenomenon and absence of backscattering. Here we
investigate how spatial modulations of the Fermi velocity in two-dimensional
Dirac materials can give rise to localization effects, with either full
(zero-dimensional) confinement or partial (one-dimensional) confinement
possible depending on the geometry of the velocity modulation. We present
several exactly solvable models illustrating the nature of the bound states
which arise, revealing how the gradient of the Fermi velocity is crucial for
determining fundamental properties of the bound states such as the zero-point
energy. We discuss the implications for guiding electronic waves in few-mode
waveguides formed by Fermi velocity modulation.Comment: 9 pages, 6 figure
Bielectron vortices in two-dimensional Dirac semimetals
Searching for new states of matter and unusual quasiparticles in emerging
materials and especially low-dimensional systems is one of the major trends in
contemporary condensed matter physics. Dirac materials, which host
quasiparticles which are described by ultrarelativistic Dirac-like equations,
are of a significant current interest from both a fundamental and applied
physics perspective. Here we show that a pair of two-dimensional massless
Dirac-Weyl fermions can form a bound state independently of the sign of the
inter-particle interaction potential, as long as this potential decays at large
distances faster than Kepler's inverse distance law. This leads to the
emergence of a new type of energetically-favourable quasiparticle: bielectron
vortices, which are double-charged and reside at zero-energy. Their bosonic
nature allows for condensation and may give rise to Majorana physics without
invoking a superconductor. These novel quasiparticles arguably explain a range
of poorly understood experiments in gated graphene structures at low doping.Comment: 9 pages, 2 figure
One-dimensional Coulomb problem in Dirac materials
We investigate the one-dimensional Coulomb potential with application to a
class of quasirelativistic systems, so-called Dirac-Weyl materials, described
by matrix Hamiltonians. We obtain the exact solution of the shifted and
truncated Coulomb problems, with the wavefunctions expressed in terms of
special functions (namely Whittaker functions), whilst the energy spectrum must
be determined via solutions to transcendental equations. Most notably, there
are critical bandgaps below which certain low-lying quantum states are missing
in a manifestation of atomic collapse.Comment: 7 pages, 5 figure
Massless Dirac fermions in two dimensions: Confinement in nonuniform magnetic fields
We show how it is possible to trap two-dimensional massless Dirac fermions in
spatially inhomogeneous magnetic fields, as long as the formed magnetic quantum
dot (or ring) is of a slowly decaying nature. It is found that a modulation of
the depth of the magnetic quantum dot leads to successive
confinement-deconfinement transitions of vortexlike states with a certain
angular momentum, until a regime is reached where only states with one sign of
angular momentum are supported. We illustrate these characteristics with both
exact solutions and a hitherto unknown quasi-exactly solvable model utilizing
confluent Heun functions.Comment: 7 pages, 3 figure
Agents of Soviet Decline: Mass Media Representations of Prostitution During Perestroika
In 1986, the Soviet newspaper Komsomolskaya pravda printed an article titled “Nina of Minsk” detailing the scandalous adventures of a prostitute-turned-brothel owner. The first of its kind, this article horrified and fascinated the Soviet reading public in equal measure, serving as an initial exposure to the topic of prostitution in the mass media.
The conversation surrounding prostitution became more heated in light of the Soviet Union’s failing economy, as well as the policy of glasnost’, which freed the press from rigid censorship. Prostitution rapidly became a popular topic of debate due to its illicit nature and impact on labor and public health issues. In response to these concerns, individuals from all walks of life began writing letters to newspapers explaining their views on prostitution. This public conversation about prostitution thus reflected a broader set of social and economic anxieties, and offers historians specific insight into how the Soviet public was reacting to the economic turmoil that rocked the Soviet Union in the 1980s. This thesis will explore this conversation and how the mass media’s focus on prostitution reveals concerns about broader social issues, including shifting gender norms, standards of morality, and public health, more specifically associated with fears about the spread of AIDS
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