Theory of holey twistsonic media

Rotating two overlapping lattices relative to each other produces the well known moiré interference patterns and has surprisingly led to strongly correlated superconductivity in twisted bilayer graphene. This seminal effect that is associated with electrons occupying flat dispersion bands has stimulated a surge of activities in classical wave physics such as acoustics to explore equivalent scenarios. Here, we mimic twisted bilayer physics by employing a rigorous sound wave expansion technique to conduct band engineering in holey bilayer plates, i.e., twistsonic media. Our numerical findings show how one flexibly is able to design moiré sound interference characteristics that alone are controlled by the twist angle and the interlayer air separation. More specifically, our numerical approach provides a significant advantage in both computational speed and storage size in comparison with widely used commercial finite-element-method solvers. We foresee that our findings should stimulate further studies in terms of band engineering and exotic topological twisted phases.J.C. acknowledges the support from the European Research Council (ERC) through the Starting Grant 714577 PHONOMETA. Z.Z. acknowledges the support from the NSFC (12104226), the China National Postdoctoral Program for Innovative Talents (BX20200165) and the China Postdoctoral Science Foundation (2020M681541). D.T. acknowledges the support of MINECO through a Ramón y Cajal grant (Grant No. RYC-2016-21188) and of the Ministry of Science, Innovation and Universities trough project number RTI2018-093921-A-C42

Multiple scattering theory of non-Hermitian sonic second-order topological insulators

Topological phases of sound enable unconventional confinement of acoustic energy at the corners in higher-order topological insulators. These unique states which go beyond the conventional bulk-boundary correspondence have recently been extended to non-Hermitian wave physics comprising finite crystal structures including loss and gain units. We use a multiple scattering theory to calculate these topologically trapped complex states that agree very well to finite element predictions. Moreover, our semi-numerical tool allows us to compute the spectral dependence of corner states in the presence of defects, illustrating the limits of the topological resilience of these confined non-Hermitian acoustic states

PRÁCTICAS DE DISCRIMINACIÓN LABORAL EN MÉXICO, POR ANTECEDENTES PENALES

El objetivo general de esta investigación es analizar profundamente, la problemática que gira en torno a las prácticas discriminatorias en el ámbito laboral hacia personas ex convictas en México, para que de esta manera se pueda plantear una posible solución dotada de viabilidad. El propósito principal de esta investigación es examinar y detallar los elementos que conforman la discriminación laboral en México, especialmente por Antecedentes Penales. Planteando una serie de definiciones para así despejar dudas y concluir situaciones implícitas, pues desde luego la no discriminación es necesaria para el correcto y mejor funcionamiento de una sociedad. Probablemente el tema de la igualdad sea repetitivo en la presente investigación, ya que atendiendo al criterio del destacado Dr. Jesús Rodríguez Zepeda: “En el texto se insiste una y otra vez en el carácter de derecho fundamental de la no discriminación, para el acceso a las oportunidades socialmente disponibles” sobre todo el derecho al trabajo. Es preciso definir respecto al tema tratado, que es una sociedad justa, entendiendo que “una sociedad justa es aquella en la que no existen, o al menos no son significativos, los tratos de desprecio hacia grupos completos por razón de una característica o atributo (como el hecho de contar con Antecedentes Penales) que además han sido estigmatizados y asociados con inferioridad y falta de valor”, se habla del estigma bajo el que están catalogados, equivocadamente, las personas con Antecedentes Penales y su exclusión en el ámbito laboral

Ancient Landslide Reactivation at the Viaduct No. 1 Located on the Caraca-La-Guaira Highway in Venezuela

Reactivation of an ancient landslide detected in 1987 affected the southern side of the Viaduct No.1 located in the Caracas-La Guaira highway, which connects Caracas, capital of Venezuela, with its main seaport and the Simon Bolivar International Airport. The Viaduct was built in 1953 and covered a gorge of approximately 300 m. It consisted of three parallel double-hinged arch ribs made of plain concrete spanning over approximately 152 m and two smaller access Viaducts on either side of the arch rib span. This paper summarizes the results from geotechnical investigation, the evaluation of inclinometers readings and surface control points and the main rehabilitation measures conducted on the structure

Ultrathin Acoustic Parity-Time Symmetric Metasurface Cloak

Invisibility or unhearability cloaks have beenmade possible by using metamaterials enabling light or sound to flow around obstacle without the trace of reflections or shadows. Metamaterials are known for being flexible building units that can mimic a host of unusual and extreme material responses, which are essential when engineering artificial material properties to realize a coordinate transforming cloak. Bending and stretching the coordinate grid in space require stringent material parameters; therefore, small inaccuracies and inevitablematerial losses become sources for unwanted scattering that are decremental to the desired effect.These obstacles further limit the possibility of achieving a robust concealment of sizeable objects from either radar or sonar detection. By using an elaborate arrangement of gain and lossy acousticmedia respecting parity-time symmetry, we built a one-way unhearability cloak able to hide objects seven times larger than the acoustic wavelength. Generally speaking, our approach has no limits in terms of working frequency, shape, or size, specifically though we demonstrate how, in principle, an object of the size of a human can be hidden from audible sound

KheOps: Cost-effective Repeatability, Reproducibility, and Replicability of Edge-to-Cloud Experiments

Distributed infrastructures for computation and analytics are now evolving towards an interconnected ecosystem allowing complex scientific workflows to be executed across hybrid systems spanning from IoT Edge devices to Clouds, and sometimes to supercomputers (the Computing Continuum). Understanding the performance trade-offs of large-scale workflows deployed on such complex Edge-to-Cloud Continuum is challenging. To achieve this, one needs to systematically perform experiments, to enable their reproducibility and allow other researchers to replicate the study and the obtained conclusions on different infrastructures. This breaks down to the tedious process of reconciling the numerous experimental requirements and constraints with low-level infrastructure design choices.To address the limitations of the main state-of-the-art approaches for distributed, collaborative experimentation, such as Google Colab, Kaggle, and Code Ocean, we propose KheOps, a collaborative environment specifically designed to enable cost-effective reproducibility and replicability of Edge-to-Cloud experiments. KheOps is composed of three core elements: (1) an experiment repository; (2) a notebook environment; and (3) a multi-platform experiment methodology.We illustrate KheOps with a real-life Edge-to-Cloud application. The evaluations explore the point of view of the authors of an experiment described in an article (who aim to make their experiments reproducible) and the perspective of their readers (who aim to replicate the experiment). The results show how KheOps helps authors to systematically perform repeatable and reproducible experiments on the Grid5000 + FIT IoT LAB testbeds. Furthermore, KheOps helps readers to cost-effectively replicate authors experiments in different infrastructures such as Chameleon Cloud + CHI@Edge testbeds, and obtain the same conclusions with high accuracies (> 88% for all performance metrics)

ProvLight: Efficient Workflow Provenance Capture on the Edge-to-Cloud Continuum

Modern scientific workflows require hybrid infrastructures combining numerous decentralized resources on the IoT/Edge interconnected to Cloud/HPC systems (aka the Computing Continuum) to enable their optimized execution. Understanding and optimizing the performance of such complex Edge-to-Cloud workflows is challenging. Capturing the provenance of key performance indicators, with their related data and processes, may assist in understanding and optimizing workflow executions. However, the capture overhead can be prohibitive, particularly in resource-constrained devices, such as the ones on the IoT/Edge.To address this challenge, based on a performance analysis of existing systems, we propose ProvLight, a tool to enable efficient provenance capture on the IoT/Edge. We leverage simplified data models, data compression and grouping, and lightweight transmission protocols to reduce overheads. We further integrate ProvLight into the E2Clab framework to enable workflow provenance capture across the Edge-to-Cloud Continuum. This integration makes E2Clab a promising platform for the performance optimization of applications through reproducible experiments.We validate ProvLight at a large scale with synthetic workloads on 64 real-life IoT/Edge devices in the FIT IoT LAB testbed. Evaluations show that ProvLight outperforms state-of-the-art systems like ProvLake and DfAnalyzer in resource-constrained devices. ProvLight is 26 -- 37x faster to capture and transmit provenance data; uses 5 -- 7x less CPU; 2x less memory; transmits 2x less data; and consumes 2 -- 2.5x less energy. ProvLight and E2Clab are available as open-source tools

Evaluación del posicionamiento preciso a través de los receptores GPS LEA-6T, NEO-M8T y ZED-F9P de bajo costo

Se comparó el posicionamiento obtenido en dos casos de estudios dependientes de las distancias (~31 y ~4.9 Km) a través del método estático mediante el uso de receptores de bajo costo de simple (LEA-6T y NEO-M8T) y doble frecuencia (ZED-F9P); tomando como referencia un receptor de orden geodésico Geomax Zenith 25. Asimismo, el posicionamiento fue evaluado con a la normativa vigente en México para el Circulo de Error Probable (CEP) y Exactitud Posicional Vertical (EPV) con una incertidumbre del 95%. Seencuentran discrepancias entre coordenadas para un mismo punto en el sistema ENU, valores mínimos de ~ 2 mm y ~ 10 mm, para una distancia ~31 y ~4.9 Km, respectivamente, obteniendo el mejor resultado con el receptor de una frecuencia LEA-M8T para la distancia de ~31 km; para el caso ~4.9 km se presenta con el receptor ZED-F9P en conjunto con una antena de orden Geodésico. Por otro lado, los resultados muestran un grado de cumplimiento en el posicionamiento de los receptores de bajo costo favorable donde; se obtienen valores de 8 mm de variación máxima para CEP; para EPV al 95% de confiabilidad, 1 cm de discrepancia. Presentando los mejores resultados los receptores LEA-6T y NEO-M8T, caso ~31 km, en cuanto a CEP y EPV.   A comparative study between the positioning obtained in two case studies depending on distances (~31 and ~4.9 km) was carried out through the static method of survey using the low-cost receivers of single (LEA-6T and NEO-M8T) and double frequency (ZED-F9P). The reference was taken as Geomax Zenith 25 geodetic order receiver. The positioning was evaluated with the current regulations in Mexico for the Circle of Probable Error (CEP) and Vertical Positional Accuracy (EPV) with an uncertainty of 95%. The discrepancies between coordinates for the same point in the ENU system were found to be the minimum values of ~ 2 mm and ~ 10 mm for a distance of ~31 and ~4.9 Km, respectively. The best results were obtained with the NEO-M8T single frequency receiver for the distance of ~31 km and for the distance of ~4.9 km, it is presented with the ZED-F9P receiver in conjunction with a geodetic antenna. Whereas on the other hand, the results show a degree of compliance in the positioning of low-cost receivers wherein the variation values of a maximum of 8 mm are obtained for CEP and for EPV 1 cm discrepancy was observed at 95% reliability. The LEA-6T and NEO-M8T receivers presented the best results for the case of ~31 km, in terms of CEP and EPV