4,221 research outputs found
Entanglement induced by a single-mode heat environment
A thermal field, which frequently appears in problems of decoherence,
provides us with minimal information about the field. We study the interaction
of the thermal field and a quantum system composed of two qubits and find that
such a chaotic field with minimal information can nevertheless entangle the
qubits which are prepared initially in a separable state. This simple model of
a quantum register interacting with a noisy environment allows us to understand
how memory of the environment affects the state of a quantum register.Comment: 13pages, 3 figure
Stochastic simulations of the quantum Zeno effect
Published versio
Machine Learning Assisted Characterization of Labyrinthine Pattern Transitions
We present a comprehensive approach to characterizing labyrinthine structures
that often emerge as a final steady state in pattern forming systems. We employ
machine learning based pattern recognition techniques to identify the types and
locations of topological defects of the local stripe ordering to augment
conventional Fourier analysis. A pair distribution function analysis of the
topological defects reveals subtle differences between labyrinthine structures
which are beyond the conventional characterization methods. We utilize our
approach to highlight a clear morphological transition between two zero-field
labyrinthine structures in single crystal Bi substituted Yttrium Iron Garnet
films. An energy landscape picture is proposed to understand the athermal
dynamics that governs the observed morphological transition. Our work
demonstrates that machine learning based recognition techniques enable novel
studies of rich and complex labyrinthine type structures universal to many
pattern formation systems
Elucidating novel disease mechanisms in severe asthma
Corticosteroids are broadly active and potent anti-inflammatory agents that, despite the introduction of biologics, remain as the mainstay therapy for many chronic inflammatory diseases, including inflammatory bowel diseases, nephrotic syndrome, rheumatoid arthritis, chronic obstructive pulmonary disease and asthma. Significantly, there are cohorts of these patients with poor sensitivity to steroid treatment even with high doses, which can lead to many iatrogenic side effects. The dose-limiting toxicity of corticosteroids, and the lack of effective therapeutic alternatives, leads to substantial excess morbidity and healthcare expenditure. We have developed novel murine models of respiratory infection-induced, severe, steroid-resistant asthma that recapitulate the hallmark features of the human disease. These models can be used to elucidate novel disease mechanisms and identify new therapeutic targets in severe asthma. Hypothesis-driven studies can elucidate the roles of specific factors and pathways. Alternatively, 'Omics approaches can be used to rapidly generate new targets. Similar approaches can be used in other diseases
On the evolution of superposition of squeezed displaced number states with the multiphoton Jaynes-Cummings model
In this paper we discuss the quantum properties for superposition of squeezed
displaced number states against multiphoton Jaynes-Cummings model (JCM). In
particular, we investigate atomic inversion, photon-number distribution,
purity, quadrature squeezing, Mandel parameter and Wigner function. We show
that the quadrature squeezing for three-photon absorption case can exhibit
revivals and collapses typical to those occurring in the atomic inversion for
one-photon absorption case. Also we prove that for odd number absorption
parameter there is a connection between the evolution of the atomic inversion
and the evolution of the Wigner function at the origin in phase space.
Furthermore, we show that the nonclassical states whose the Wigner functions
values at the origins are negative will be always nonclassical when they are
evolving through the JCM with even absorption parameter. Also we demonstrate
that various types of cat states can be generated via this system.Comment: 27 pages, 10 figure
Diagnosing idiopathic learning disability: a cost-effectiveness analysis of microarray technology in the National Health Service of the United Kingdom
Array based comparative genomic hybridisation (aCGH) is a powerful technique for detecting clinically relevant genome imbalance and can offer 40 to > 1000 times the resolution of karyotyping. Indeed, idiopathic learning disability (ILD) studies suggest that a genome-wide aCGH approach makes 10â15% more diagnoses involving genome imbalance than karyotyping. Despite this, aCGH has yet to be implemented as a routine NHS service. One significant obstacle is the perception that the technology is prohibitively expensive for most standard NHS clinical cytogenetics laboratories. To address this, we investigated the cost-effectiveness of aCGH versus standard cytogenetic analysis for diagnosing idiopathic learning disability (ILD) in the NHS. Cost data from four participating genetics centres were collected and analysed. In a single test comparison, the average cost of aCGH was ÂŁ442 and the average cost of karyotyping was ÂŁ117 with array costs contributing most to the cost difference. This difference was not a key barrier when the context of follow up diagnostic tests was considered. Indeed, in a hypothetical cohort of 100 ILD children, aCGH was found to cost less per diagnosis (ÂŁ3,118) than a karyotyping and multi-telomere FISH approach (ÂŁ4,957). We conclude that testing for genomic imbalances in ILD using microarray technology is likely to be cost-effective because long-term savings can be made regardless of a positive (diagnosis) or negative result. Earlier diagnoses save costs of additional diagnostic tests. Negative results are cost-effective in minimising follow-up test choice. The use of aCGH in routine clinical practice warrants serious consideration by healthcare providers
Hemodynamic alterations and regional myocardial blood flow during supraceliac aortic occlusion in dogs with a critical coronary stenosis
The hemodynamic consequences and myocardial blood flow alterations associated with cross-clamping of the thoracic aorta were studied during pentobarbital (control), halothane (1 MAC), and isoflurane (1 MAC) anesthesia in dogs with a critical stenosis of the left circumflex coronary artery. Aortic clamping at the level of the diaphragm resulted in significant and equivalent increases in mean aortic pressure and left atrial pressure during the control clamp, halothane clamp, and isoflurane clamp periods. Likewise, aortic clamping resulted in a significant and equivalent decrease in cardiac output during control-clamp, halothane clamp, and isoflurane clamp. Myocardial contractility as assessed by dP/dt was depressed during halothane and isoflurane anesthesia when compared with control, but no further change in contractility was associated with aortic clamping. No signifcant alterations in regional or transmural myocardial bloc flow were found with halothane or isoflurane anesthesia, c with aortic clamping during halothane or isoflurane anesthesia. It is concluded that there are significant hemodynami consequences associated with aortic clamping, that neithe halothane nor isoflurane anesthesia alters these consequences when compared with pentobarbital anesthesia alone and that the deterioration in myocardial function observe during aortic clamping with halothane and isoflurane anesthesia cannot be attributed to any maldistribution of myocardh blood flow.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29461/1/0000544.pd
Compressive properties of min-mod-type limiters in modelling shockwave-containing flows
The long-ignored compressive properties of Min-mod-type limiter is investigated in this manuscript by demonstrating its potential in numerically modelling shockwave-containing flows, especially in shock wave/boundary layer interaction (SWBLI) problems. Theoretical studies were firstly performed based on Swebyâs total variation diminishing (TVD) limiter region and Spekreijseâs monotonicity-preserving limiter region to indicate Min-mod-type limitersâ compressive properties. The influence of limiters on the solution accuracy was evaluated using a hybrid-order analysis method based on the grid-independent study in three typical shockwave-containing flows. The conclusions are that, Min-mod-type limiter can be utilized as a dissipative and/or compressive limiter, but depending on the reasonable value of the compression parameter. The compressive Min-mod limiter tends to be more attractive in modelling shockwave-containing flows as compared to other commonly preferred limiters because of its stable computational process and its high-resolution predictions. However, the compressive Min-mod limiter may suffer from its slightly poor convergence, as that observed in other commonly accepted smooth limiters in modelling SWBLI problems. Š 2020, The Author(s)
Preparation and control of a cavity-field state through atom-driven field interaction: towards long-lived mesoscopic states
The preparation of mesoscopic states of the radiation and matter fields
through atom-field interactions has been achieved in recent years and employed
for a range of striking applications in quantum optics. Here we present a
technique for the preparation and control of a cavity mode which, besides
interacting with a two-level atom, is simultaneously submitted to linear and
parametric amplification processes. The role of the amplification-controlling
fields in the achievement of real mesoscopic states, is to produce
highly-squeezed field states and, consequently, to increase both: i) the
distance in phase space between the components of the prepared superpositions
and ii) the mean photon number of such superpositions. When submitting the
squeezed superposition states to the action of similarly squeezed reservoirs,
we demonstrate that under specific conditions the decoherence time of the
states becomes independent of both the distance in phase space between their
components and their mean photon number. An explanation is presented to support
this remarkable result, together with a discussion on the experimental
implementation of our proposal. We also show how to produce number states with
fidelities higher than those derived as circular states
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