Semiclassical Propagation of Wavepackets with Complex and Real Trajectories

International audienceWe consider a semiclassical approximation, first derived by Heller and coworkers, for the time evolution of an originally Gaussian wave packet in terms of complex trajectories. We also derive additional approximations replacing the complex trajectories by real ones. These yield three different semiclassical formulae involving different real trajectories. One of these formulae is Heller's thawed Gaussian approximation. The other approximations are non-Gaussian and may involve several trajectories determined by mixed initial–final conditions. These different formulae are tested for the cases of scattering by a hard wall, scattering by an attractive Gaussian potential and bound motion in a quartic oscillator. The formula with complex trajectories gives good results in all cases. The non-Gaussian approximations with real trajectories work well in some cases, whereas the thawed Gaussian works only in very simple situations

Hopf algebras and Markov chains: Two examples and a theory

The operation of squaring (coproduct followed by product) in a combinatorial Hopf algebra is shown to induce a Markov chain in natural bases. Chains constructed in this way include widely studied methods of card shuffling, a natural "rock-breaking" process, and Markov chains on simplicial complexes. Many of these chains can be explictly diagonalized using the primitive elements of the algebra and the combinatorics of the free Lie algebra. For card shuffling, this gives an explicit description of the eigenvectors. For rock-breaking, an explicit description of the quasi-stationary distribution and sharp rates to absorption follow.Comment: 51 pages, 17 figures. (Typographical errors corrected. Further fixes will only appear on the version on Amy Pang's website, the arXiv version will not be updated.

Tocopherol and fatty acids content and proximal composition of four avocado cultivars (Persea Americana Mill)

Avocado pulp is widely regarded as a great source of edible oil containing fat-soluble vitamins and omega-3 fatty acids (FA). However, avocado peel and seeds are also good sources of edible oil and are less explored byproducts. This paper aimed at determining the proximal composition, FA and tocopherol contents of the pulp, peel, and seeds of Quintal, Fortuna, Margarida, and Hass avocado cultivars. The pulps presented high concentrations of oleic acid. In addition, peel and seeds presented lower omega-6/omega-3 ratios than the pulp. There was also a considerable amount of tocopherol in the peel and seeds, especially in Hass peel (230.7 mg/100 g). According to the results, the peel and seeds of avocado that are considered byproducts, can be utilized in food industry

Food bioactive compounds and emerging techniques for their extraction: Polyphenols as a case study

Experimental studies have provided convincing evidence that food bioactive compounds (FBCs) have a positive biological impact on human health, exerting protective effects against noncommunicable diseases (NCD) including cancer and cardiovascular (CVDs), metabolic, and neurodegenerative disorders (NDDs). These benefits have been associated with the presence of secondary metabolites, namely polyphenols, glucosinolates, carotenoids, terpenoids, alkaloids, saponins, vitamins, and fibres, among others, derived from their antioxidant, antiatherogenic, anti-inflammatory, antimicrobial, antithrombotic, cardioprotective, and vasodilator properties. Polyphenols as one of the most abundant classes of bioactive compounds present in plant-based foods emerge as a promising approach for the development of efficacious preventive agents against NCDs with reduced side effects. The aim of this review is to present comprehensive and deep insights into the potential of polyphenols, from their chemical structure classification and biosynthesis to preventive effects on NCDs, namely cancer, CVDs, and NDDS. The challenge of polyphenols bioavailability and bioaccessibility will be explored in addition to useful industrial and environmental applications. Advanced and emerging extraction techniques will be highlighted and the high-resolution analytical techniques used for FBCs characterization, identification, and quantification will be considered.FCT (Fundação para a Ciência e a Tecnologia) through the CQM Base Fund-UIDB/00674/ 2020, the Programmatic Fund- UIDP/00674/2020, and the PhD fellowship SFRH/BD/116895/2016 granted to João Gonçalves. Madeira 14–20 Program, project PROEQUIPRAM-Reforço do Investimento em Equipamentos e Infraestruturas Científicas RAM (M1420-01-0145-FEDER-000008), ARDITIAgência Regional para o Desenvolvimento da Investigação Tecnologia e Inovação through the project M1420-01-0145-FEDER-000005-Centro de Química da Madeira-CQM+ (Madeira 14–20 Program) and Project M1420-09-5369-FSE-000001 for the Post-Doctoral fellowship granted to JAMP. Núcleo Regional da Madeira da Liga Portuguesa Contra o Cancro (NRM-LPCC) for the professional internship granted to Joselin Aguiar. FCT for financial support by national funds FCT/MCTES to CIMO (UIDB/00690/2020). National funding by FCT, P.I., through the institutional scientific employment program-contract for L. Barros, and B.R. Albuquerque research grant (SFRH/BD/136370/2018). European Regional Development Fund (ERDF) through the Regional Operational Program North 2020, within the scope of the project Mobilizador Norte-01-0247-FEDER-024479: ValorNatural®. FEDER-Interreg España-Portugal programme for financial support through the project 0377_Iberphenol_ 6_E and TRANSCoLAB 0612_TRANS_CO_LAB_2_P. R.C.G. Corrêa is a research grant recipient of Cesumar Institute of Science Technology and Innovation (ICETI).info:eu-repo/semantics/publishedVersio

Texture Quantification in Y Ba 2 Cu 3 O 7 Superconducting Films

Una capa superconductora epitaxial de Y Ba2Cu3 7 es el resultado de un óptimo proceso de crecimiento epitaxial de los granos superconductores. Además, la epitaxia del sustrato tiene una directa repercusión en la microestructura y las propiedades físicas de la capa. Por medio de técnicas de caracterización convencionales, tales como: microscopía electrónica de barrido, y difracción de rayos X, permiten realizar una rápida valoración de la calidad de la epitaxia por medio de la cuantificación de la textura de la capa. Presentamos los resultados de la cuantificación de la textura en capas superconductoras de Y Ba2Cu3O7 .Y Ba2Cu3O7 epitaxial superconducting film is consequence of an optimum epitaxial growth process of superconducting grains. Also, the substrate's epitaxy has a direct repercussion on the lm microstructure and its physical properties. Conventional characterization techniques such as: scanning electronic microscopy, and x ray difrraction, allowed us to obtain a quick assessment of epitaxy quality through of texture quantification of the film. We present the results of texture quantification in Y Ba2Cu3O7 superconducting films

Challenges and opportunities of gravitational-wave searches at MHz to GHz frequencies

The first direct measurement of gravitational waves by the LIGO and Virgo collaborations has opened up new avenues to explore our Universe. This white paper outlines the challenges and gains expected in gravitational-wave searches at frequencies above the LIGO/Virgo band, with a particular focus on Ultra High-Frequency Gravitational Waves (UHF-GWs), covering the MHz to GHz range. The absence of known astrophysical sources in this frequency range provides a unique opportunity to discover physics beyond the Standard Model operating both in the early and late Universe, and we highlight some of the most promising gravitational sources. We review several detector concepts that have been proposed to take up this challenge, and compare their expected sensitivity with the signal strength predicted in various models. This report is the summary of the workshop “Challenges and opportunities of high-frequency gravitational wave detection” held at ICTP Trieste, Italy in October 2019, that set up the stage for the recently launched Ultra-High-Frequency Gravitational Wave (UHF-GW) initiative

Um balanço das políticas do governo Lula para a educação superior: continuidade e ruptura

Resumo O trabalho apresenta e analisa as principais políticas para o setor privado de educação superior adotadas pelo governo de Luiz Inácio Lula da Silva (2003/2010). A partir de uma retrospectiva histórica e de uma análise de sua implementação, as políticas são consideradas por meio de uma revisão crítica da literatura e dos dados oficiais. O trabalho demonstra que, apesar de ter realizado políticas para o setor público bastante distintas das do governo de Fernando Henrique Cardoso, no caso do setor privado, há antes um aprofundamento das opções políticas já desenvolvidas durante o governo de Cardoso. Essas opções se traduzem em ações de fomento ao desenvolvimento do setor privado, na medida em que ampliaram o financiamento deste e consolidaram um marco legal que proporcionou segurança jurídica às mantenedoras. Esse fomento, entretanto, veio acompanhado de um sensível aumento e aperfeiçoamento dos mecanismos de controle sobre o crescimento do setor privado