An efficient flamelet progress-variable method for modeling non-premixed flames in weak electric fields

Combustion stabilization and enhancement of the flammability limits are mandatory objectives to improve nowadays combustion chambers. At this purpose, the use of an electric field in the flame region provides a solution which is, at the same time, easy to implement and effective to modify the flame structure. The present work describes an efficient flamelet progress-variable approach developed to model the fluid dynamics of flames immersed in an electric field. The main feature of this model is that it can use complex ionization mechanisms without increasing the computational cost of the simulation. The model is based on the assumption that the combustion process is not directly influenced by the electric field and has been tested using two chemi-ionization mechanisms of different complexity in order to examine its behavior with and without the presence of heavy anions in the mixture. Using a one- and two-dimensional numerical test cases, the present approach has been able to reproduce all the major aspects encountered when a flame is subject to an imposed electric field and the main effects of the different chemical mechanisms. Moreover, the proposed model is shown to produce a large reduction in the computational cost, being able to shorten the time needed to perform a simulation up to 40 times.Comment: 26 pages, 13 figures, paper accepted for publication on Computers and Fluid

Entanglement control in hybrid optomechanical systems

We demonstrate the control of entanglement in a hybrid optomechanical system comprising an optical cavity with a mechanical end-mirror and an intracavity Bose-Einstein condensate (BEC). Pulsed laser light (tuned within realistic experimental conditions) is shown to induce an almost sixfold increase of the atom-mirror entanglement and to be responsible for interesting dynamics between such mesoscopic systems. In order to assess the advantages offered by the proposed control technique, we compare the time-dependent dynamics of the system under constant pumping with the evolution due to the modulated laser light.Comment: Published versio

Entanglement production by quantum error correction in the presence of correlated environment

We analyze the effect of a quantum error correcting code on the entanglement of encoded logical qubits in the presence of a dephasing interaction with a correlated environment. Such correlated reservoir introduces entanglement between physical qubits. We show that for short times the quantum error correction interprets such entanglement as errors and suppresses it. However for longer time, although quantum error correction is no longer able to correct errors, it enhances the rate of entanglement production due to the interaction with the environment.Comment: 7 pages, 3 figures, published versio

Normal form decomposition for Gaussian-to-Gaussian superoperators

In this paper we explore the set of linear maps sending the set of quantum Gaussian states into itself. These maps are in general not positive, a feature which can be exploited as a test to check whether a given quantum state belongs to the convex hull of Gaussian states (if one of the considered maps sends it into a non positive operator, the above state is certified not to belong to the set). Generalizing a result known to be valid under the assumption of complete positivity, we provide a characterization of these Gaussian-to-Gaussian (not necessarily positive) superoperators in terms of their action on the characteristic function of the inputs. For the special case of one-mode mappings we also show that any Gaussian-to-Gaussian superoperator can be expressed as a concatenation of a phase-space dilatation, followed by the action of a completely positive Gaussian channel, possibly composed with a transposition. While a similar decomposition is shown to fail in the multi-mode scenario, we prove that it still holds at least under the further hypothesis of homogeneous action on the covariance matrix

Analysis of the SET/FTY720 Complex by NMR Reveals a Unique Mechanism for the Activation of PP2A

Protein phosphatase 2A (PP2A) is a major serine/threonine phosphatase with tumor suppressor function. PP2A holoenzyme contains numerous combinations of its various isoforms of scaffolding (A), regulatory (B), and catalytic (C) subunits. In many cancer types, an endogenous PP2A inhibitor, inhibitor 2 of PP2A (SET) oncoprotein, is overexpressed, resulting in PP2A inhibition, leading to enhanced cell growth, and attenuation of cell death. It is known that targeting SET with bioactive sphingolipid ceramide or sphingolipid analogue drug FTY720 leads to the reactivation of PP2A, leading to necroptosis. However, structural details of the interaction between SET and FTY720 (or ceramide) with regards to mechanism of the PP2A activation have been unknown. Here, we report the first in solution examination of SET-sphingolipid complex by NMR spectroscopy. Data revealed that FTY720 binding may result in a structural shift in the N-terminal region of SET, which prevents its oligomerization. This then leads to the release of SET from the catalytic subunit of a specific PP2A holoenzyme, which comprises PP2AAβ, PP2A-B56γ, and PP2ACα subunits, for increased PP2A activity, while SET remains associated with the PP2A-B56γ. The activation of this specific PP2A holoenzyme by SET-FTY720 complex then regulates a number of downstream effector proteins involved in various biological functions, such as tumor suppressor non-muscle myosin IIA. Attenuation of FTY720-SET association by point mutations enhances SET- PP2A inhibitory complex, leading to resistance to PP2A activation, which is recapitulated by R71A and E111A SET mutations

Nutritional Education and Promotion in Central America Through Dietary Guidelines Development

Malnutrition has been one of the major health problems which affects two of every ten children, under five years old, in Central American countries. During recent years, in addition to malnutrition problems, almost all Central American countries have reported an increase in the incidence of chronic illness such as diabetes, cardio-vascular diseases and some cancers. This tendency has been associated with the increase of overweight and obesity among the adult population, especially among women. Both poor nutrition and over nutrition constitute high priority health problems, which need to be addressed through comprehensive health promotion programs that includes a strong component of nutrition educaiton. The strategies and actions to promote appropriate diets and healthy lifestyles, that emanated from the last International Conference on Nutrition (FAO 1992), includes: - nutrition education and dietary guidance for the general public - training of professionals in health care, agriculture extension and related services - development of food-services guidelines - involvement of consumer groups and the food industry - ensuring food quality and safety - monitoring and evaluating national food and nutrition situations - encouraging the availability of the variety of foods needed to meet consumer demand To accomplish these recommendations many sectors need to take an active role in the promotion of healthy habits. The public sector, including health professionals can work to educate the general public about diet and health. The food industry plays an essential role by responding to consumer demand to produce and market the variety of foods needed for a healthy diet. Both the formal and non-formal education system must play a central role, incorporating nutrition into education in general, and within the context of local culture. In addition to school systems, the health and agriculture sector, public information channels, unions, youth groups and community leaders should take an active role in education and promotion of nutrition healthy lifestyles (FAO 1992). I believe that the first step, to carry out such a comprehensive nutrition promotion strategy should be the development of dietary guidelines, as the basis of information that every sector should use as they develop their own educational programs, directed to different populations, applying different educational strategies. The purpose of this document is to present a model of dietary guidelines and graphic design to promote health and nutrition in Central American Countries, as well as a proposal to implement these dietary guidelines. To develop the model of dietary guidelines, experiences from different countries, such as the United States, Mexico and Venezuela were reviewed and adapted. Graphic designs from fourteen countries were reviewed. The content of this document is presented in four sections: the first one presents a bibliographic review of dietary guidelines development in the United States and Latin American countries. The second demonstrates the adaptation and application of these concepts to the development of the Guatemalan dietary guidelines and graphic design. The third section introduces a bibliographic review of the recommendations to implement dietary guidelines in the United States, as well as my suggestion to develop and implement dietary guidelines in Central American countries. In the last section I present some ideas about the application of non-formal education strategies, to adapt the dietary guidelines at community level. This document will be translated into Spanish, and will be reviewed by a team of nutritionists, communicators and educators from the Institute of Nutrition of Central America and Panama. After that, this document will be disseminated to other Latin American countries and could be used as the basis to develop dietary guidelines in Latin American countries

Influence of electromagnetic interferences on the gravimetric sensitivity of surface acoustic waveguides

Surface acoustic waveguides are increasing in interest for (bio)chemical detection. The surface mass modification leads to measurable changes in the propagation properties of the waveguide. Among a wide variety of waveguides, Love mode has been investigated because of its high gravimetric sensitivity. The acoustic signal launched and detected in the waveguide by electrical transducers is accompanied by an electromagnetic wave; the interaction of the two signals, easily enhanced by the open structure of the sensor, creates interference patterns in the transfer function of the sensor. The influence of these interferences on the gravimetric sensitivity is presented, whereby the structure of the entire sensor is modelled. We show that electromagnetic interferences generate an error in the experimental value of the sensitivity. This error is different for the open and the closed loop configurations of the sensor. The theoretical approach is completed by the experimentation of an actual Love mode sensor operated under liquid in open loop configuration. The experiment indicates that the interaction depends on the frequency and the mass modifications.Comment: 28 pages, 8 figure

Cavity-aided quantum parameter estimation in a bosonic double-well Josephson junction

We describe an apparatus designed to make non-demolition measurements on a Bose-Einstein condensate (BEC) trapped in a double-well optical cavity. This apparatus contains, as well as the bosonic gas and the trap, an optical cavity. We show how the interaction between the light and the atoms, under appropriate conditions, can allow for a weakly disturbing yet highly precise measurement of the population imbalance between the two wells and its variance. We show that the setting is well suited for the implementation of quantum-limited estimation strategies for the inference of the key parameters defining the evolution of the atomic system and based on measurements performed on the cavity field. This would enable {\it de facto} Hamiltonian diagnosis via a highly controllable quantum probe.Comment: 8 pages, 5 figures, RevTeX4; Accepted for publication in Phys. Rev.

The First Fermi-LAT SNR Catalog SNR and Cosmic Ray Implications

Galactic cosmic ray (CRs) sources, classically proposed to be Supernova Remnants (SNRs), must meet the energetic particle content required by direct measurements of high energy CRs. Indirect gamma-ray measurements of SNRs with the Fermi Large Area Telescope (LAT) have now shown directly that at least three SNRs accelerate protons. With the first Fermi LAT SNR Catalog, we have systematically characterized the GeV gamma-rays emitted by 279 SNRs known primarily from radio surveys. We present these sources in a multiwavelength context, including studies of correlations between GeV and radio size, flux, and index, TeV index, and age and environment tracers, in order to better understand effects of evolution and environment on the GeV emission. We show that previously sufficient models of SNRs' GeV emission no longer adequately describe the data. To address the question of CR origins, we also examine the SNRs' maximal CR contribution assuming the GeV emission arises solely from proton interactions. Improved breadth and quality of multiwavelength data, including distances and local densities, and more, higher resolution gamma-ray data with correspondingly improved Galactic diffuse models will strengthen this constraint.Comment: 8 pages, 10 figures; in Proceedings of the 34th International Cosmic Ray Conference (ICRC 2015), The Hague (The Netherlands