284 research outputs found
The Influence of a Compressed Semester on Student Performance in a Career and Technical Course
A thesis presented to the faculty of the College of Business and Technology at Morehead State University in partial fulfillment of the requirements for the Degree Master of Science by Michael W. Hazzard on April 21, 2022
Queenie With Her Hair in a Braid
https://digitalcommons.library.umaine.edu/mmb-vp/6095/thumbnail.jp
High-intensity two-frequency photoassociation spectroscopy of a weakly bound molecular state: theory and experiment
We investigate two-frequency photoassociation of a weakly bound molecular
state, focusing on a regime where the ac Stark shift is comparable to the
halo-state energy. In this "high-intensity" regime, we observe features absent
in low-intensity two-frequency photoassociation. We experimentally measure the
spectra of Sr atoms coupled to the least bound state of the
Sr ground electronic channel through an intermediate electronically
excited molecular state. We compare the spectra to a simple three-level model
that includes a two-frequency drive on each leg of the transition. With
numerical solution of the time-dependent Schrodinger equation, we show that
this model accurately captures (1) the existence of experimentally observed
satellite peaks that arise from nonlinear processes, (2) the locations of the
two-photon peak in the spectrum, including ac Stark shifts, and (3) in some
cases, spectral lineshapes. To better understand these numerical results, we
develop an approximate treatment of this model, based on Floquet and
perturbation theory, that gives simple formulas that accurately capture the
halo-state energies. We expect these expressions to be valuable tools to
analyze and guide future two-frequency photoassociation experiments.Comment: 12 pages, 7 figure
A Novel Dielectric Anomaly in Cuprates and Nickelates: Signature of an Electronic Glassy State
The low-frequency dielectric response of hole-doped insulators
La_{2}Cu_{1-x}Li_{x}O_{4} and La_{2-x}Sr_{x}NiO_{4} shows a large dielectric
constant \epsilon ^{'} at high temperature and a step-like drop by a factor of
100 at a material-dependent low temperature T_{f}. T_{f} increases with
frequency and the dielectric response shows universal scaling in a Cole-Cole
plot, suggesting that a charge glass state is realized both in the cuprates and
in the nickelates.Comment: 5 pages, 4 figure
Exploring quantum criticality based on ultracold atoms in optical lattices
Critical behavior developed near a quantum phase transition, interesting in
its own right, offers exciting opportunities to explore the universality of
strongly-correlated systems near the ground state. Cold atoms in optical
lattices, in particular, represent a paradigmatic system, for which the quantum
phase transition between the superfluid and Mott insulator states can be
externally induced by tuning the microscopic parameters. In this paper, we
describe our approach to study quantum criticality of cesium atoms in a
two-dimensional lattice based on in situ density measurements. Our research
agenda involves testing critical scaling of thermodynamic observables and
extracting transport properties in the quantum critical regime. We present and
discuss experimental progress on both fronts. In particular, the thermodynamic
measurement suggests that the equation of state near the critical point follows
the predicted scaling law at low temperatures.Comment: 15 pages, 6 figure
SU(N) magnetism in chains of ultracold alkaline-earth-metal atoms: Mott transitions and quantum correlations
We investigate one dimensional SU Hubbard chains at zero temperature,
which can be emulated with ultracold alkaline earth atoms, by using the density
matrix renormalization group (DMRG), Bethe ansatz (BA), and bosonization. We
compute experimental observables and use the DMRG to benchmark the accuracy of
the Bethe ansatz for where the BA is only approximate. In the worst case,
we find a relative error in the BA ground state energy
for at filling 1/N, which is due to the fact that BA improperly
treats the triply and higher occupied states. Using the DMRG for and
the BA for large , we determine the regimes of validity of strong- and
weak-coupling perturbation theory for all values of and in particular, the
parameter range in which the system is well described by a SU Heisenberg
model at filling 1/N. We find this depends only weakly on . We investigate
the Berezinskii-Kosterlitz-Thouless phase transition from a Luttinger liquid to
a Mott-insulator by computing the fidelity susceptibility and the Luttinger
parameter at 1/N filling. The numerical findings give strong evidence
that the fidelity susceptibility develops a minimum at a critical interaction
strength which is found to occur at a finite positive value for .Comment: 19 pages, 13 figures and 2 tables; slightly revised version as
published in Phys. Rev.
Crafting interactive decoration
© 2017 ACM. everyday artefacts. This involves adorning them with decorative patterns that enhance their beauty while triggering digital interactions when scanned with cameras. These are realized using an existing augmented reality technique that embeds computer readable codes into the topological structures of hand-drawn patterns. We describe a research through design process that engaged artisans to craft a portfolio of interactive artefacts, including ceramic bowls, embroidered gift cards, fabric souvenirs, and an acoustic guitar. We annotate this portfolio with reflections on the crafting process, revealing how artisans addressed pattern, materials, form and function, and digital mappings throughout their craft process. Further reflection on our portfolio reveals how they bridged between human and system perceptions of visual patterns and engaged in a deep embedding of digital interactions into physical materials. Our findings demonstrate the potential for interactive decoration, distilling the craft knowledge involved in creating aesthetic and functional decoration, highlight the need for transparent computer vision technologies, and raise wider issues for HCI's growing engagement with craft
What do older people learn from young people? : Intergenerational learning in ‘day centre’ community settings in Malta
This study analyses what motivates older people to attend ‘day centres’ in Malta and what they believe that they derive from young people who carry out their placements at these day ‘centres’ These young people, who are aged 16–17, attend a vocational college in Malta and are studying health and social care. The study is based on a qualitative approach and employs the usage of focus groups. The main findings are that the elderly see the students as helping them on an emotional level by giving them encouragement, and on a practical level, by offering them insights that help them in modern-day life
Complementary hydro-mechanical coupled finite/discrete element and microseismic modelling to predict hydraulic fracture propagation in tight shale reservoirs
This paper presents a novel approach to predict the propagation of hydraulic fractures in tight shale reservoirs. Many hydraulic fracture modelling schemes assume that the fracture direction is pre-seeded in the problem domain discretization. This is a severe limitation as the reservoir often contains large numbers of pre-existing fractures that strongly influence the direction of the propagating fracture. To circumvent these shortcomings a new fracture modelling treatment is proposed where the introduction of discrete fracture surfaces is based on new and dynamically updated geometrical entities rather than the topology of the underlying spatial discretization. Hydraulic fracturing is an inherently coupled engineering problem with interactions between fluid flow and fracturing when the stress state of the reservoir rock attains a failure criterion. This work follows a staggered hydro-mechanical coupled finite/discrete element approach to capture the key interplay between fluid pressure and fracture growth. In field practice the fracture growth is hidden from the design engineer and microseismicity is often used to infer hydraulic fracture lengths and directions. Microsesimic output can also be computed from changes of the effective stress in the geomechanical model and compared against field microseismicity. A number of hydraulic fracture numerical examples are presented to illustrate the new technology
- …