Search results for "Coherence"
showing 10 items of 905 documents
Coherent master equation for laser modelocking
2020
Modelocked lasers constitute the fundamental source of optically-coherent ultrashort-pulsed radiation, with huge impact in science and technology. Their modeling largely rests on the master equation (ME) approach introduced in 1975 by Hermann A. Haus. However, that description fails when the medium dynamics is fast and, ultimately, when light-matter quantum coherence is relevant. Here we set a rigorous and general ME framework, the coherent ME (CME), that overcomes both limitations. The CME predicts strong deviations from Haus ME, which we substantiate through an amplitude-modulated semiconductor laser experiment. Accounting for coherent effects, like the Risken-Nummedal-Graham-Haken multim…
Diversity in Coherence : Strengths and Opportunities of Three Programs
2017
Author's accepted version (post-print). Although teacher educators may perceive their program and courses to be coherent, the question remains to what extent student teachers also are able to perceive the linkages within their programs. Coherence within teacher education programs is important for teacher candidates to build understanding of teaching. Our study draws upon survey data from 269 teacher candidates, in three different teacher education programs, located in three different countries (Norway, Finland, United States [California]) and compares these candidates’ perceptions of the coherence of their teacher education programs. Candidates from a program that has explicitly been workin…
Enseñanza de las ciencias : revista de investigación y experiencias didácticas
2021
La biodiversidad es un concepto complejo, convertido en un importante referente curricular. Esta investigación explora si un ejercicio avanzado de las competencias necesarias para hacer significativo el concepto de biodiversidad en diferentes contextos conlleva una mejora significativa de la calidad de los argumentos implicados en la toma de decisiones sobre conservación de la biodiversidad. Para ello se ha aplicado una metodología cualitativa al análisis de doce argumentos formulados por estudiantes de 1.º de Bachillerato, caracterizados por su elevada complejidad estructural, de los cuales se muestra uno a modo de ejemplo. Los resultados revelan que, a pesar del nivel de cohesión estructu…
Sense of coherence and psychological well-being in cardiac patients: Is the association mediated by self-efficacy?
2019
Aim of the studyA large deal of research on cardiac patients concentrates on analyses of mutual relationships between sense of coherence and psychological well-being, sense of coherence and self-efficacy, or psychological well-being and self-efficacy. It has been proven that self-efficacy plays a crucial role as a mediator of the relationships between various psychological constructs.Subject or material and methodsA total number of 176 patients (82 women and 94 men), age 45-82 years (M = 58.56, SD = 8.25) participated in the study. All participants were patients admitted to the cardiology department with coronary heart disease and undergoing medical interventions. All participants were aske…
Experimental approach for testing the uncoupling between cardiovascular variability series
2002
In cardiovascular variability analysis, the significance of the coupling between two series is commonly assessed by defining a zero level on the magnitude-squared coherence (MSC). Although the use of the conventional value of 0.5 does not consider the dependence of MSC estimates on the analysis parameters, a theoretical threshold Tt is available only for the weighted covariance (WC) estimator. In this study, an experimental threshold for zero coherence Te was derived by a statistical test from the sampling distribution of MSC estimated on completely uncoupled time series. MSC was estimated by the WC method (Parzen window, spectral bandwidth B = 0.015, 0.02, 0.025, 0.03 Hz) and by the parame…
Time Series Corrections and Analyses in Thermal Remote Sensing
2013
The time span of surface thermal data bases now reaches a few decades. However, studies using surface thermal time series are seldom, due to the difficulty of obtaining temporally coherent estimations for this parameter. Applications for surface thermal multitemporal analysis range from climate change studies and modeling to anomaly detection for natural or industrial hazard detection. This chapter presents methods to improve the temporal coherence of temperature time series, through data reconstruction of atmospheric and cloud contaminated observations, and through the correction of the orbital drift effect which hinders the use of the longest data sets. Then, methods for the analysis of t…
Population trapping due to cavity losses
2008
In population trapping the occupation of a decaying quantum level keeps a constant non-zero value. We show that an atom-cavity system interacting with an environment characterized by a non-flat spectrum, in the non-Markovian limit, exhibits such a behavior, effectively realizing the preservation of nonclassical states against dissipation. Our results allow to understand the role of cavity losses in hybrid solid state systems and pave the way to the proper description of leakage in the recently developed cavity quantum electrodynamic systems.
Entanglement trapping in structured environments
2008
The entanglement dynamics of two independent qubits each embedded in a structured environment under conditions of inhibition of spontaneous emission is analyzed, showing entanglement trapping. We demonstrate that entanglement trapping can be used efficiently to prevent entanglement sudden death. For the case of realistic photonic band-gap materials, we show that high values of entanglement trapping can be achieved. This result is of both fundamental and applicative interest since it provides a physical situation where the entanglement can be preserved and manipulated, e.g. by Stark-shifting the qubit transition frequency outside and inside the gap.
Phase Coherence in Conceptual Spaces for Conversational Agents
2010
This chapter attempts to enhance the traditional chatbots with associative/intuitive capabilities. According to these considerations, it tries to create a conversational agent model that takes into consideration, aside from the traditional rule - based dialogue mechanism, also some sort of intuitive reasoning ability. The aim is in attempting to overcome the rigid pattern - matching rules, proposing a "phase coherence" paradigm into a semantic space. With this locution the chapter intend that the vectors representing the elements of the dialogue are coherent with the context. The chapter trust that this intuitive - associative capability can be obtained using the LSA methodology. The repres…
Early Confucian Legal Thought: A Theory of Natural Law?
2015
Confucianism has often been compared to natural law, mainly to its non-volunta- ristic currents. However, the possibility to include Confucianism in the group of natural law theories is problematic. Recently, a few scholars, and notably Peerenboom, have challenged the widely shared thesis that Confucius and early Confucian thinkers should be mentioned in the ranks of natural law philosophers. He contends that early Confucian jurisprudence is more profitably compared to Dworkin’s coherence theory of law than to natural law. The present article discusses three core points: the laws of nature and natural law, the connection between law and morality, and the basic epistemological assumptions pr…