Generating high-order exceptional points in coupled electronic oscillators using complex synthetic gauge fields

Exceptional points (EPs) are degeneracies of non-Hermitian systems, where both eigenvalues and eigenvectors coalesce. Classical and quantum systems exhibiting high-order EPs have recently been identified as fundamental building blocks for the development of novel, ultra-sensitive opto-electronic devices. However, arguably one of their major drawbacks is that they rely on non-linear amplification processes that could limit their potential applications, particularly in the quantum realm. In this work, we show that high-order EPs can be designed by means of linear, time-modulated, chain of inductively coupled RLC (where R stands for resistance, L for inductance, and C for capacitance) electronic circuits. With a general theory, we show that $N$ coupled circuits with $2N$ dynamical variables and time-dependent parameters can be mapped onto an $N$-site, time-dependent, non-Hermitian Hamiltonian, and obtain constraints for $\mathcal{PT}$-symmetry in such models. With numerical calculations, we obtain the Floquet exceptional contours of order $N$ by studying the energy dynamics in the circuit. Our results pave the way toward realizing robust, arbitrary-order EPs by means of synthetic gauge fields, with important implications for sensing, energy transfer, and topology

Development of Surface-Coated Polylactic Acid/Polyhydroxyalkanoate (PLA/PHA) Nanocomposites

This work reports on the design and development of nanocomposites based on a polymeric matrix containing biodegradable Polylactic Acid (PLA) and Polyhydroxyalkanoate (PHA) coated with either Graphite NanoPlatelets (GNP) or silver nanoparticles (AgNP). Nanocomposites were obtained by mechanical mixing under mild conditions and low load contents (<0.10 wt %). This favours physical adhesion of the additives onto the polymer surface, while the polymeric bulk matrix remains unaffected. Nanocomposite characterisation was performed via optical and focused ion beam microscopy, proving these nanocomposites are selectively modified only on the surface, leaving bulk polymer unaffected. Processability of these materials was proven by the fabrication of samples via injection moulding and mechanical characterisation. Nanocomposites showed enhanced Young modulus and yield strength, as well as better thermal properties when compared with the unmodified polymer. In the case of AgNP coated nanocomposites, the surface was found to be optically active, as observed in the increase of the resolution of Raman spectra, acquired at least 10 times, proving these nanocomposites are promising candidates as surface enhanced Raman spectroscopy (SERS) substrates

Influence of cerebral vasodilation on blood reelin levels in growth restricted fetuses

Fetal growth restriction (FGR) is one of the most important obstetric pathologies. It is frequently caused by placental insufficiency. Previous studies have shown a relationship between FGR and impaired new-born neurodevelopment, although the molecular mechanisms involved in this association have not yet been completely clarified. Reelin is an extracellular matrix glycoprotein involved in development of neocortex, hippocampus, cerebellum and spinal cord. Reelin has been demonstrated to play a key role in regulating perinatal neurodevelopment and to contribute to the emergence and development of various psychiatric pathologies, and its levels are highly influenced by pathological conditions of hypoxia. The purpose of this article is to study whether reelin levels in new-borns vary as a function of severity of fetal growth restriction by gestational age and sex. We sub-grouped fetuses in: normal weight group (Group 1, n = 17), FGR group with normal umbilical artery Doppler and cerebral redistribution at middle cerebral artery Doppler (Group 2, n = 9), and FGR with abnormal umbilical artery Doppler (Group 3, n = 8). Our results show a significant association of elevated Reelin levels in FGR fetuses with cerebral blood redistribution compared to the normal weight group and the FGR with abnormal umbilical artery group. Future research should focus on further expanding the knowledge of the relationship of reelin and its regulated products with neurodevelopment impairment in new-borns with FGR and should include larger and more homogeneous samples and the combined use of different in vivo techniques in neonates with impaired growth during their different adaptive phases. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

Eficacia de la alta presión hidrostática como tratamiento cuarentenario para mejorar la calidad de los frutos del mango infestados por la mosca de la fruta Mexicana Anastrepha ludens

High hydrostatic pressure (HPP) has been reported as an alternative quarantine process in fruits infested by Ceratitis capitata Wiedemann, Rhagoletis indifferens Curran and Cydia pomonella (L.). In Mexico and other Latin-American countries, the Mexican fruit fly Anastrepha ludens Loew is one of the most important insects infesting mangoes, citrus, and other fruits. The present study aimed to determine the effect of pressure level and time on the survival of eggs and larvae of the Mexican fruit fly. Eggs and larvae were pressurized at 25, 50, 75, 100, or 150 MPa for 0, 5, 10 or 20 min at 25 8C. Ripe and green mangoes were also pressurized under the same conditions. On pressurized eggs of 1, 2, 3, and 4 days old, their ability to hatch was recorded. On pressurized first, second and third instars, the percentage of survival was registered. Furthermore, third instars were studied for their ability to pupate and to develop adults. The results showed that although most of eggs and larvae died at pressures lower than 100 MPa, some of them were able to survive even at 150 MPa, and a few third instars were able to pupate and to develop to adulthood. Green mangoes were affected by pressures above 75 MPa but they were more resistant than ripe mangoes. HPP treatments seem to be feasible as a quarantine process for mangoes; however, more studies, such as combining HPP with temperature treatments, are needed in order to decrease the pressure level to avoid fruit damageLa alta presión hidrostática ha sido descrita como un proceso de cuarentena alternativa en frutas infestadas por Ceratitis capitata Wiedemann, Rhagoletis indifferens Curran y Cydia pomonella (L.). En México y otros países Latinoamericanos, la mosca de la fruta mexicana Anastrepha ludens Loew es uno de los más importantes insectos que infestan los mangos, cítricos y otras frutas. El presente estudio tuvo como meta determinar el efecto del nivel de presión y tiempo sobre la supervivencia de huevos y larvas de la mosca de la fruta mexicana. Huevos y larvas se presurizaron a 25, 50, 75, 100, y 150 MPa durante 0, 5, 10, y 20 min a 25 8C. Mangos maduros y verdes también se presurizaron bajo las mismas condiciones. En huevos presurizados de uno, dos, tres y cuatro días de vida, se registró su capacidad para eclosionar. En primera, segunda y tercera etapa larvaria presurizada, el porcentaje de supervivencia también se registró. Además, en la tercera etapa larvaria se estudió su capacidad para salir de la crisálida y desarrollar adultos. Los resultados mostraron que aunque la mayoría de los huevos y larvas murieron a presiones por debajo de 100 MPa, algunos de ellos fueron capaces de sobrevivir aun a 150 MPa, y unas pocas larvas de tercera etapa fueron capaces de salir de la crisálida y desarrollar adultos. Los mangos verdes se vieron afectados por las presiones por encima de 75 MPa pero fueron más resistentes que los mangos maduros. Los tratamientos de alta presión hidrostática parecen ser un proceso viable como método cuarentenario para mangos, sin embargo, se necesitan más estudios tales como la combinación de alta presión hidrostática junto con tratamientos térmicos para disminuir los niveles de presión y evitar daños en la frutaThe authors are grateful to Fondo Mixto CONACYT –Gobierno del Estado de Tamaulipas for the financial support of this work (Project TAMPS-2003-C02-15), to CONACYT for the scholarship granted to author Hugo Ernesto CandelarioS

Smart Machine Vision for Universal Spatial Mode Reconstruction

Structured light beams, in particular those carrying orbital angular momentum (OAM), have gained a lot of attention due to their potential for enlarging the transmission capabilities of communication systems. However, the use of OAM-carrying light in communications faces two major problems, namely distortions introduced during propagation in disordered media, such as the atmosphere or optical fibers, and the large divergence that high-order OAM modes experience. While the use of non-orthogonal modes may offer a way to circumvent the divergence of high-order OAM fields, artificial intelligence (AI) algorithms have shown promise for solving the mode-distortion issue. Unfortunately, current AI-based algorithms make use of large-amount data-handling protocols that generally lead to large processing time and high power consumption. Here we show that a low-power, low-cost image sensor can itself act as an artificial neural network that simultaneously detects and reconstructs distorted OAM-carrying beams. We demonstrate the capabilities of our device by reconstructing (with a 95$\%$ efficiency) individual Vortex, Laguerre-Gaussian (LG) and Bessel modes, as well as hybrid (non-orthogonal) coherent superpositions of such modes. Our work provides a potentially useful basis for the development of low-power-consumption, light-based communication devices

DISTRIBUCIÓN GEOGRÁFICA Y ECOLÓGICA DE LA FLORA AMENAZADA DE EXTINCIÓN EN LA ZONA ÁRIDA DEL ESTADO DE SAN LUIS POTOSÍ, MÉXICO

The objective of the present study is todetermine which of the endangered plant taxalisted in the 1994 Norma Oficial Mexicana(NOM-059-ECOL-1994) are present in thearid zones of San Luis Potosí and to analyze togeographical and ecological distributions ofthese taxa in the state, 29 species and 5varieties in 18 genera and 5 families are present,42% of the endangered species are found inrosette scrub, 33% in microphyllousshrublands, 20% in desert grassland and 5% incrassicaulous vegetation. The presence of 25 ofthe 29 endangered species was noted in thecorridor formed by the eastern slope of theSierra de Librillos and the western slope of theierra La Trinidad, an area which includes partsof the municipios of Matehuala, Villa deGuadalupe, Guadalcázar, Cerritos and VillaHidalgo. Many of these species are endemicand hence vulnerable to extinction.Ante la presencia en la zona árida del estado deSan Luis Potosí de especies de plantasconsideradas bajo algún tipo de riesgo, seplantearon como objetivos identificar cuáles delos taxa mencionados en la NOM-059-ECOL-1994 se encuentran en el área de estudio yanalizar su distribución geográfica y ecológica.Se localizaron cinco familias botánicas, 18géneros, 29 especies y cinco variedades, bajoalguna de las categorías de la Norma OficialMexicana (1994). En el matorral desérticorosetófilo se concentra la mayoría de lasespecies (42%), le siguen el matorral desérticomicrófilo (33%), el zacatal (20%) y el matorralcrasicaule (5%). De las 29 especies estudiadas,25 se encuentran en el corredor formado por lavertiente oriental de la Sierra de Librillos y lavertiente occidental de la Sierra La Trinidad,que comprende parte de los municipios deMatehuala, Villa de Guadalupe, Guadalcázar,Cerritos y Villa Hidalgo, área en donde se encuentran diversas especies endémicas y por lotanto vulnerables a la extinción