3,478 research outputs found
Pathways from caring and engaging adults to youth vocational identity: the mediational roles of career search self-efficacy and goal capacity
This study examines the role played by access to caring and engaging adults, career search self-efficacy (CSSE), and goal capacity in the development of youth vocational identity. The study used a bootstrapping approach to analyze data, collected from a survey of 1,579 youths enrolled in 14 U.S. high schools, to test a hypothesized serial multiple mediation model. Results indicate both direct and multiple indirect pathways from adults influences to the youth vocational identity. Two specific pathways of influence were found through CSSE and goal capacity respectively. Additionally, a serial multiple mediation effect was found whereby CSSE and goal capacity collectively mediated the relationship. This indicates that greater access to caring and engaging adults contributes to higher CSSE, which accounts for a higher level of goal capacity, and eventually leads to the better vocational identity in youth. These findings establish notable implications for practices that are discussed in closing.First author draf
Quantified Uncertainty in Thermodynamic Modeling for Materials Design
Phase fractions, compositions and energies of the stable phases as a function
of macroscopic composition, temperature, and pressure (X-T-P) are the principle
correlations needed for the design of new materials and improvement of existing
materials. They are the outcomes of thermodynamic modeling based on the
CALculation of PHAse Diagrams (CALPHAD) approach. The accuracy of CALPHAD
predictions vary widely in X-T-P space due to experimental error, model
inadequacy and unequal data coverage. In response, researchers have developed
frameworks to quantify the uncertainty of thermodynamic property model
parameters and propagate it to phase diagram predictions. In previous studies,
uncertainty was represented as intervals on phase boundaries (with respect to
composition) or invariant reactions (with respect to temperature) and was
unable to represent the uncertainty in eutectoid reactions or in the stability
of phase regions. In this work, we propose a suite of tools that leverages
samples from the multivariate model parameter distribution to represent
uncertainty in forms that surpass previous limitations and are well suited to
materials design. These representations include the distribution of phase
diagrams and their features, as well as the dependence of phase stability and
the distributions of phase fraction, composition activity and Gibbs energy on
X-T-P location - irrespective of the total number of components. Most
critically, the new methodology allows the material designer to interrogate a
certain composition and temperature domain and get in return the probability of
different phases to be stable, which can positively impact materials design
Lasing oscillation condition and group delay control in gain-assisted plasmon-induced transparency
A gain-assisted plasmonic waveguide with two detuned resonators is
investigated in the plasmon-induced transparency window. Phase map is employed
to study power transmittance and group delay for varying gain coefficients and
frequency detunings of the two resonators. The gain coefficient for lasing
oscillation condition is analytically shown to vary quadratically with the
frequency detuning. In the amplification regime below the lasing threshold, the
spectrum implies not only large group delay, but also high transmittance and
narrow linewidth. This is in contrast to those in the loss-compensation regime
and the passive case in which there always exists a trade-off between the
linewidth and the peak transmittance.Comment: 15 pages, 4 figure
Enhanced transmission of optically thick metallic films at infrared wavelengths
For an optically thick metallic film, the transmission for both s- and
p-polarized waves is extremely low. If the metallic film is coated on both
sides with a finite dielectric layer, light transmission for -polarized
waves can be enhanced considerably. This enhancement is not related to surface
plasmon-polaritions. Instead, it is due to the interplay between Fabry-Perot
interference in the coated dielectric layer and the existence of the Brewster
angle at the dielectric/metallic interface. It is shown that the coated
metallic films can act as excellent polarizers at infrared wavelengths.Comment: 3 pages, 4 figures. Submitted to Appl. Phys. Let
Ground state and edge excitations of quantum Hall liquid at filling factor 2/3
We present a numerical study of fractional quantum Hall liquid at Landau
level filling factor in a microscopic model including long-range
Coulomb interaction and edge confining potential, based on the disc geometry.
We find the ground state is accurately described by the particle-hole conjugate
of a Laughlin state. We also find there are two counter-propagating
edge modes, and the velocity of the forward-propagating mode is larger than the
backward-propagating mode. The velocities have opposite responses to the change
of the background confinement potential. On the other hand changing the
two-body Coulomb potential has qualitatively the same effect on the velocities;
for example we find increasing layer thickness (which softens of the Coulomb
interaction) reduces both the forward mode and the backward mode velocities.Comment: 12 pages, 13 figure
Fractional quantum Hall effect at : Ground states, non-Abelian quasiholes, and edge modes in a microscopic model
We present a comprehensive numerical study of a microscopic model of the
fractional quantum Hall system at filling fraction , based on the
disc geometry. Our model includes Coulomb interaction and a semi-realistic
confining potential. We also mix in some three-body interaction in some cases
to help elucidate the physics. We obtain a phase diagram, discuss the
conditions under which the ground state can be described by the Moore-Read
state, and study its competition with neighboring stripe phases. We also study
quasihole excitations and edge excitations in the Moore-Read--like state. From
the evolution of edge spectrum, we obtain the velocities of the charge and
neutral edge modes, which turn out to be very different. This separation of
velocities is a source of decoherence for a non-Abelian quasihole/quasiparticle
(with charge ) when propagating at the edge; using numbers obtained
from a specific set of parameters we estimate the decoherence length to be
around four microns. This sets an upper bound for the separation of the two
point contacts in a double point contact interferometer, designed to detect the
non-Abelian nature of such quasiparticles. We also find a state that is a
potential candidate for the recently proposed anti-Pfaffian state. We find the
speculated anti-Pfaffian state is favored in weak confinement (smooth edge)
while the Moore-Read Pfaffian state is favored in strong confinement (sharp
edge).Comment: 15 pages, 9 figures; Estimate of e/4 quasiparticle/hole coherence
length when propagating along the edge modified in response to a recent
revision of Ref. 25, and minor changes elsewher
The Universal Edge Physics in Fractional Quantum Hall Liquids
The chiral Luttinger liquid theory for fractional quantum Hall edge transport
predicts universal power-law behavior in the current-voltage (-)
characteristics for electrons tunneling into the edge. However, it has not been
unambiguously observed in experiments in two-dimensional electron gases based
on GaAs/GaAlAs heterostructures or quantum wells. One plausible cause is the
fractional quantum Hall edge reconstruction, which introduces non-chiral edge
modes. The coupling between counterpropagating edge modes can modify the
exponent of the - characteristics. By comparing the fractional
quantum Hall states in modulation-doped semiconductor devices and in graphene
devices, we show that the graphene-based systems have an experimental
accessible parameter region to avoid the edge reconstruction, which is suitable
for the exploration of the universal edge tunneling exponent predicted by the
chiral Luttinger liquid theory.Comment: 7 pages, 6 figure
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