1,861 research outputs found
Engineering and harnessing giant atoms in high-dimensional baths: a cold atoms' implementation
Emitters coupled simultaneously to distant positions of a photonic bath, the
so-called giant atoms, represent a new paradigm in quantum optics. When coupled
to one-dimensional baths, as recently implemented with transmission lines or
SAW waveguides, they lead to striking effects such as chiral emission or
decoherence-free atomic interactions. Here, we show how to create giant atoms
in dynamical state-dependent optical lattices, which offers the possibility of
coupling them to structured baths in arbitrary dimensions. This opens up new
avenues to a variety of phenomena and opportunities for quantum simulation. In
particular, we show how to engineer unconventional radiation patterns, like
multi-directional chiral emission, as well as collective interactions that can
be used to simulate non-equilibrium many-body dynamics with no analogue in
other setups. Besides, the recipes we provide to harness giant atoms in high
dimensions can be exported to other platforms where such non-local couplings
can be engineered.Comment: 9 pages, 5 figures. Title changed to accommodate to the new focus of
the main text. Several typos correcte
Emitters of -photon bundles
We propose a scheme based on the coherent excitation of a two-level system in
a cavity to generate an ultrabright CW and focused source of quantum light that
comes in groups (bundles) of photons, for an integer tunable with the
frequency of the exciting laser. We define a new quantity, the \emph{purity} of
-photon emission, to describe the percentage of photons emitted in bundles,
thus bypassing the limitations of Glauber correlation functions. We focus on
the case and show that close to 100% of two-photon emission and
90% of three-photon emission is within reach of state of the art cavity QED
samples. The statistics of the bundles emission shows that various
regimes---from -photon lasing to -photon guns---can be realized. This is
evidenced through generalized correlation functions that extend the standard
definitions to the multi-photon level.Comment: Introduce the n-th order N-photon correlation functions. Reorganized
to emphasize the N-photon emitter, now extended to the antibunching regime,
rather than only coherent emission as previsoul
Impact of Fluid Substitution on the Performance of an Axial Compressor Blade Cascade Working with Supercritical Carbon Dioxide
Abstract
Recent research on turbomachinery design and analysis for supercritical carbon dioxide (sCO2) power cycles has relied on computational fluid dynamics. This has produced a large number of works whose approach is mostly case-specific, rather than of general application to sCO2 turbomachinery design. As opposed to such approach, this work explores the aerodynamic performance of compressor blade cascades operating on air and supercritical CO2 with the main objective to evaluate the usual aerodynamic parameters of the cascade for variable boundary conditions and geometries, enabling “full” or “partial” similarity. The results present both the global performance of the cascades and certain features of the local flow (trailing edge and wake). The discussion also highlights the mechanical limitations of the analysis (forces exerted on the blades), which is the main restriction for applying similarity laws to extrapolate the experience gained through decades of work on air turbomachinery to the new working fluid. This approach is a step toward the understanding and appropriate formulation of a multi-objective optimization problem for the design of such turbomachinery components where sCO2 is used as the operating fluid. With this objective, the paper aims to identify and analyze what would be expected if a common description of such computational design problems similar to those where air is the working fluid were used.</jats:p
Energy evaluation of extruded compound foods for dogs by near-infrared spectroscopy
Near-infrared reflectance spectroscopy (NIRS) was used to predictthe chemical composition, the apparent digestibility and the content ofdigestible nutrients and energy of commercial extruded compoundfoods fordogs
Reducing techno-anxiety in high school teachers by improving their ICT problem-solving skills
Teachers need to continuously update their information and communication technologies (ICT) knowledge, but they are usually not trained to deal with the problems arising from their use. In fact, studies in the literature report techno-anxiety (i.e. unpleasant physiological activation and discomfort due to present or future use of ICT) in teachers. Thus, the goal of this action research is to study if teachers’ techno-anxiety can be reduced by increasing their ability to solve technological problems. An inter-subject experiment has been carried out with 46 teachers. High school teachers were chosen because they are digital immigrants, while at the moment of this research their students are digital natives (born around year 2000). Since we could not find any specific training for teachers to increase their resolution skills of technological problems, in order to apply the treatment for our study, we have designed and deployed an online course about ICT problem-solving skills based on the 70/20/10 model for learning and development. Results show the success of the course when it comes to increasing the ICT problem-solving skills and to reducing techno-anxiety.Preprin
Estadística Descriptiva y Probabilidad: (Teoría y problemas)
XXXIV, 261 p. ; 24 cm.Libro ElectrónicoÍndice
Bibliografía: p. [256]-258
Manual para alumnos de titulaciones experimentales que proporciona una visión práctica e intuitiva de la estadística descriptiva y el cálculo de probabilidades, campos básicos y fundamentales de la ciencia estadísticaLibro : Español (spa) : 3a. edIndice general
Prólogo XIII
1. Introducción XIII
2. History (Histórico) XV
3. Licencia de Documentación Libre de GNU XVI
4. GNU Free Documentation License XXVI
A Estadística Descriptiva 1
1 Síntesis de la información 7
1. Rese˜na histórica 7
2. La organización de la información 9
3. Representaciones grá?cas 15
4. Medidas centrales 17
5. Medidas de posición 26
6. Medidas de dispersión 27
7. Desigualdad de Tchebychev 31
8. Momentos de la distribución 31
9. Medidas de forma 33
10. Transformaciones 36
11. Análisis exploratorio de datos 37
12. Ejercicios 40
2 Análisis conjunto de variables. 53
1. Distribución conjunta de dos caracteres 53
2. Distribuciones marginales 55
3. Distribuciones condicionadas 55
4. Independencia 60
5. Medidas de dependencia. Coeficientes de relación 61
6. Ejercicios 78
3 Ajuste y regresión bidimensional 89
1. Introducción 89
2. Ajuste. Criterio de los mínimos cuadrados 91
3. Análisis de la bondad del ajuste 97
4. Regresión. Método de regresión a la media 100
5. Análisis de la bondad de la regresión 102
6. Notas y conclusiones 104
7. Ejercicios 105
B Probabilidad 113
4 Teoría de la probabilidad 117
1. Evolución histórica 117
2. Conjuntos. Operaciones 120
3. Algebra de sucesos 122
4. Distintas de?niciones del concepto de probabilidad 126
5. Propiedades de la función de probabilidad 129
6. Probabilidad condicionada. Independencia 131
7. Dependencia e independencia 132
8. Teorema de la probabilidad total. Teorema de Bayes 133
9. Ejercicios 136
5 Variable aleatoria 145
1. Concepto 145
2. Variables discretas y continuas 146
3. Variables unidimensionales 147
4. Variables multidimensionales 161
5. Ejercicios 173
6 Algunos modelos probabilísticos 185
1. Distribución uniforme discreta 185
2. Experimento de Bernouilli 186
3. Distribución hipergeométrica 191
4. Proceso de Poisson 192
5. Distribución uniforme continua 195
6. Distribución normal 197
7. Relación entre binomial, Poisson y normal 200
8. Teorema central del límite 201
9. Distribución gamma 202
10. Distribución beta 203
11. Distribución de Cauchy 204
12. Distribuciones derivadas de la normal 206
13. Distribución de Laplace 210
14. Distribución logística 211
15. Distribución de Pareto 211
16. Algunos modelos multidimensionales 212
17. Ejercicios 215
A Combinatoria 225
1. Introducción 225
2. Variaciones con repetición 225
3. Variaciones 226
4. Permutaciones 226
5. Permutaciones con repetición 226
6. Combinaciones sin repetición 227
7. Combinaciones con repetición 228
8. Ejercicios 228
B Tablas Estadísticas 233
C Bibliografía 25
The colored Hanbury Brown--Twiss effect
The Hanbury Brown--Twiss effect is one of the celebrated phenomenologies of
modern physics that accommodates equally well classical (interferences of
waves) and quantum (correlations between indistinguishable particles)
interpretations. The effect was discovered in the late thirties with a basic
observation of Hanbury Brown that radio-pulses from two distinct antennas
generate signals on the oscilloscope that wiggle similarly to the naked eye.
When Hanbury Brown and his mathematician colleague Twiss took the obvious step
to propose bringing the effect in the optical range, they met with considerable
opposition as single-photon interferences were deemed impossible. The Hanbury
Brown--Twiss effect is nowadays universally accepted and, being so fundamental,
embodies many subtleties of our understanding of the wave/particle dual nature
of light. Thanks to a novel experimental technique, we report here a
generalized version of the Hanbury Brown--Twiss effect to include the frequency
of the detected light, or, from the particle point of view, the energy of the
detected photons. In addition to the known tendencies of indistinguishable
photons to arrive together on the detector, we find that photons of different
colors present the opposite characteristic of avoiding each others. We
postulate that fermions can be similarly brought to exhibit positive
(boson-like) correlations by frequency filtering.Comment: 18 pages, includes supplementary material of the derivation
Role of toxin activation on binding and pore formation activity of the Bacillus thuringiensis Cry3 toxins in membranes of Leptinotarsa decemlineata (Say)
AbstractBinding and pore formation constitute key steps in the mode of action of Bacillus thuringiensis δ-endotoxins.In this work, we present a comparative analysis of toxin-binding capacities of proteolytically processed Cry3A, Cry3B and Cry3C toxins to brush border membranes (BBMV) of the Colorado potato beetle Leptinotarsa decemlineata (CPB), a major potato coleopteran-insect pest. Competition experiments showed that the three Cry3 proteolytically activated toxins share a common binding site. Also heterologous competition experiments showed that Cry3Aa and Cry3Ca toxins have an extra binding site that is not shared with Cry3Ba toxin. The pore formation activity of the three different Cry3 toxins is analysed. High pore-formation activities were observed in Cry3 toxins obtained by proteolytical activation with CPB BBMV in contrast to toxins activated with either trypsin or chymotrypsin proteases. The pore-formation activity correlated with the formation of soluble oligomeric structures. Our data support that, similarly to the Cry1A toxins, the Cry3 oligomer is formed after receptor binding and before membrane insertion, forming a pre-pore structure that is insertion-competent
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