Digital Demodulator for BFSK waveform based upon Correlator and Differentiator Systems

The present article relates in general to digital demodulation of Binary Frequency Shift Keying (BFSK waveform) . New processing methods for demodulating the BFSK-signals are proposed here. Based on Sampler Correlator, the hardware consumption for the proposed techniques is reduced in comparison with other reported. Theoretical details concerning limits of applicability are also given by closed-form expressions. Simulation experiments are illustrated to validate the overall performance

Short-term synaptic facilitation improves information retrieval in noisy neural networks

Short-term synaptic depression and facilitation have been found to greatly influence the performance of autoassociative neural networks. However, only partial results, focused for instance on the computation of the maximum storage capacity at zero temperature, have been obtained to date. In this work, we extended the study of the effect of these synaptic mechanisms on autoassociative neural networks to more realistic and general conditions, including the presence of noise in the system. In particular, we characterized the behavior of the system by means of its phase diagrams, and we concluded that synaptic facilitation significantly enlarges the region of good retrieval performance of the network. We also found that networks with facilitating synapses may have critical temperatures substantially higher than those of standard autoassociative networks, thus allowing neural networks to perform better under high-noise conditions.Comment: 6 pages, 3 figures, to appear in EP

Tunneling Splittings in Mn12-Acetate Single Crystals

A Landau-Zener multi-crossing method has been used to investigate the tunnel splittings in high quality Mn$_{12}$-acetate single crystals in the pure quantum relaxation regime and for fields applied parallel to the magnetic easy axis. With this method several individual tunneling resonances have been studied over a broad range of time scales. The relaxation is found to be non-exponential and a distribution of tunnel splittings is inferred from the data. The distributions suggest that the inhomogeneity in the tunneling rates is due to disorder that produces a non-zero mean value of the average transverse anisotropy, such as in a solvent disorder model. Further, the effect of intermolecular dipolar interaction on the magnetic relaxation has been studied.Comment: Europhysics Letters (in press). 7 pages, including 3 figure

High-throughput variable-to-fixed entropy codec using selective, stochastic code forests

Efficient high-throughput (HT) compression algorithms are paramount to meet the stringent constraints of present and upcoming data storage, processing, and transmission systems. In particular, latency, bandwidth and energy requirements are critical for those systems. Most HT codecs are designed to maximize compression speed, and secondarily to minimize compressed lengths. On the other hand, decompression speed is often equally or more critical than compression speed, especially in scenarios where decompression is performed multiple times and/or at critical parts of a system. In this work, an algorithm to design variable-to-fixed (VF) codes is proposed that prioritizes decompression speed. Stationary Markov analysis is employed to generate multiple, jointly optimized codes (denoted code forests). Their average compression efficiency is on par with the state of the art in VF codes, e.g., within 1% of Yamamoto et al.\u27s algorithm. The proposed code forest structure enables the implementation of highly efficient codecs, with decompression speeds 3.8 times faster than other state-of-the-art HT entropy codecs with equal or better compression ratios for natural data sources. Compared to these HT codecs, the proposed forests yields similar compression efficiency and speeds

Chicanx histories of the present: a praxis against gang injunctions in Orange County, California, 2008–2016

Chicanxs Unidxs de Orange County (CU) is a community organisation in Southern California. Founded in 2006, CU is small, multigenerational and multi-ethnic. Its organising has focused predominantly on building community power by focusing on local politics, abusive policing and the gentrification of Chicanx neighbourhoods. This article presents an evidence-based narrative of several CU campaigns (primarily between 2008 and 2016). CU’s tactical aggressiveness and strategic pragmatism forced significant changes to ‘civil gang injunctions’ in California. For decades, California law enforcement has used such injunctions to suppress a generation of young people of colour as ‘gang members’. Minors and adults have been prohibited indefinitely from engaging in otherwise legal activities without due process. CU’s emphasis on the longevity of institutionalised and societal racism, rooted in the colonial conquest, resembles arguments associated with critical race theory (CRT) – though CU was not inspired by CRT. CU’s praxis resembles practices of critical pedagogy – though it was not directly modelled on it either. Rather, we argue that CU’s praxis is embedded in the members’ lived experience and study of the local history of racism, community and social movements. All five of this article’s authors were members of CU and were involved in the organising described in this article. The authors wrote this at the request of the CU membership, and it has been discussed and revised by the full membership

ANÁLISIS DEL DESEMPLEO, LA MIGRACIÓN Y LA POBREZA EN MÉXICO

La mayoría de los movimientos poblacionales en todas las regiones geográficas del mundo, obedecen principalmente a motivaciones vinculadas con la búsqueda de mejores condiciones de vida. No obstante, en casi todos los casos el costo social de lograr que los hogares reciban lo necesario para sobrevivir es la ruptura familiar y la seguridad personal.Los graves problemas que están enfrentando las economías subdesarrolladas con bajo o nulo crecimiento económico, altas tasas de desempleo, elevado índice de migración y millones de habitantes en pobreza extrema. El objetivo del presente trabajo fue analizar el desempleo, la migración y la pobreza en México. El desempleo es uno de los problemas de la economía mexicana (según INEGI de 5.5%), le sigue la migración y la pobreza extrema. Debido al incremento del desempleo y los bajos salarios que tiene el país estimulan a las personas a emigrar. Aunado a lo anterior, en Estados Unidos de América la tasa de desempleo de los migrantes mexicanos se elevó de 8.0% a 12.0% (2009) aproximadamente, provocando una fuerte disminución en las remesas, lo que trae como consecuencia una baja en los ingresos de las familias que viven de dichas transferencias ocasionando que se agudice la pobreza en el país

Causal representation of multi-loop Feynman integrands within the loop-tree duality

The numerical evaluation of multi-loop scattering amplitudes in the Feynman representation usually requires to deal with both physical (causal) and unphysical (non-causal) singularities. The loop-tree duality (LTD) offers a powerful framework to easily characterise and distinguish these two types of singularities, and then simplify analytically the underling expressions. In this paper, we work explicitly on the dual representation of multi-loop Feynman integrals generated from three parent topologies, which we refer to as Maximal, Next-to-Maximal and Next-to-Next-to-Maximal loop topologies. In particular, we aim at expressing these dual contributions, independently of the number of loops and internal configurations, in terms of causal propagators only. Thus, providing very compact and causal integrand representations to all orders. In order to do so, we reconstruct their analytic expressions from numerical evaluation over finite fields. This procedure implicitly cancels out all unphysical singularities. We also interpret the result in terms of entangled causal thresholds. In view of the simple structure of the dual expressions, we integrate them numerically up to four loops in integer space-time dimensions, taking advantage of their smooth behaviour at integrand level.Comment: 24 pages, 8 figures. v2: references added; matches published versio