Synthesis of all-digital delay lines

© 2017 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other worksThe synthesis of delay lines (DLs) is a core task during the generation of matched delays, ring oscillator clocks or delay monitors. The main figure of merit of a DL is the fidelity to track variability. Unfortunately, complex systems have a great diversity of timing paths that exhibit different sensitivities to static and dynamic variations. Designing DLs that capture this diversity is an ardous task. This paper proposes an algorithmic approach for the synthesis of DLs that can be integrated in a conventional design flow. The algorithm uses heuristics to perform a combinatorial search in a vast space of solutions that combine different types of gates and wire lengths. The synthesized DLs are (1) all digital, i.e., built of conventional standard cells, (2) accurate in tracking variability and (3) configurable at runtime. Experimental results with a commercial standard cell library confirm the quality of the DLs that only exhibit delay mismatches of about 1% on average over all PVT corners.Peer ReviewedPostprint (author's final draft

The contrastive value of lexical stress in visual word recognition: Evidence from spanish

Resumen tomado de la publicaciónEl valor contrastivo del acento léxico en el reconocimiento visual de palabras: evidencia del español. Antecedentes: muchos pares de palabras en español, en particular muchas formas verbales, difieren solo en la sílaba acentuada, tal como aNImo y aniMÓ. Así el acento puede adquirir un valor contrastivo que fue confirmado por Dupoux, Pallier, Sebastian y Mehler (1997) en español, pero no en francés, en percepción auditiva. Método: este estudio contrasta el efecto de primado en pares de palabras que difieren en su patrón de acentuación con el efecto de repetición, el primado solo de acento (sin relación ortográfica) y el primado morfológico en reconocimiento visual de palabras. Resultados: usando priming enmascarado se obtuvo facilitación para los pares con diferente acento (rasGÓ/RASgo) comparando con los pares sin relación (dorMÍ/RASgo), pero no se produjo comparando con los no relacionados de igual acento (PERsa/RASgo). Sin embargo, los pares idénticos (RASgo-RASgo) produjeron facilitación comparando con ambas condiciones ortográficamente relacionadas. Con un SOA largo los pares con diferente acento (ortográficamente iguales) produjeron una facilitación significativa, como ocurrió con los pares relacionados morfológicos (RASga/RASgo), sobre los pares ortográficamente diferentes (PERsa/RASgo). Conclusión: estos resultados confirman la importancia del procesamiento temprano y preléxico del acento para la selección léxica en español, como ocurre con las características ortográficas y fonológicas de las palabras.Universidad de Oviedo. Biblioteca de Psicología; Plaza Feijoo, s/n.; 33003 Oviedo; Tel. +34985104146; Fax +34985104126; [email protected]

Assessment of the lifetime of district heating pipes

This thesis is concerned with the degradation and assessment of the lifetime of district heating pipes, where accelerated ageing is used to study the degradation in a short time frame.The project was divided into four interrelated parts. In the first part, polyurethane foam obtained from district heating pipes was aged at an elevated temperature in two different environments, and the effects of the accelerated ageing on the physical properties and chemical structure were studied. In the second part, district heating pipes were aged using an accelerated method to examine directly the degradation of the polyurethane foam in the pipes. The adhesion strength and thermal conductivity were followed during the entire ageing process. The chemical structure of some polyurethane samples was also analysed to identify any sign of deterioration. In the third part, several naturally aged pipes were collected and their remaining adhesion strength measured, as well as their chemical structure to compare the natural and accelerated ageing. Finally, an alternative method for accelerated ageing was proposed, applying thermal and cyclic mechanical loads on the pipes at the same time and exposing the pipes to more realistic conditions than the traditional accelerated ageing.The results confirmed that oxygen plays a central role in the activation of the degradation process, which is faster at higher temperatures. The adhesion strength and thermal conductivity measurements showed that the temperature of accelerated ageing should be chosen carefully to avoid the activation of degradation processes that are not relevant for the specific application. The studies of natural ageing presented evidence that some pipes have lost only approximately 20% of their initial adhesion strength after 30 years in service. These pipes could probably be used for a longer time. Finally, the combination of thermal and cyclic mechanical loads is a promising method of accelerated ageing because mechanical loads affected both the adhesion strength and the chemical structure of the tested pipes, leading to more rapid ageing. This methodology should be adopted in accelerated ageing testing to avoid overestimating the lifetime of DH pipes

Star polymers rupture induced by constant forces

In this work, we study the breakage process of an unknotted three-arm star-shaped polymer when it is pulled from its free ends by a constant force. The star polymer configuration is described through an array of monomers coupled by anharmonic bonds, while the rupture process is tracked in three-dimensional space by means of Langevin Molecular Dynamics simulations. The interaction between monomers is described by a Morse potential, while a Weeks-Chandler-Anderson energetic contribution accounts for the excluded volume interaction. We explore the effect of the molecular architecture on the distributions of rupture times over a broad interval of pulling forces and star configurations. It was found that the rupture time distribution of the individual star arms is strongly affected by the star configuration imposed by the pulling forces and the length of the arms. We also observed that for large pulling forces the rupture time distributions resemble the dominant features observed for linear polymer chains. The model introduced here provides the basic ingredients to describe the effects of tensile forces on stress-induced degradation of branched macromolecules and polymer networks.Fil: García, Nicolás. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; ArgentinaFil: Febbo, Mariano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; ArgentinaFil: Vega, Daniel Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; ArgentinaFil: Milchev, A.. Bulgarian Academy of Sciences; Bulgari

EL PRINCIPIO CONSTITUCIONAL DE SOLIDARIDAD INTERTERRITORIAL EN ESPAÑA Y EN ALEMANIA: APLICACIÓN Y LÍMITES

El present estudi analitza l’aplicació del principi constitucional de solidaritat interterritorial a Espanya i a Alemanya centrant-se en la qüestió dels seus límits. Inicialment es presenta el cas d’Espanya, incloent tant les comunitats autònomes de règim comú com les forals i prestant especial atenció als límits a la solidaritat que va introduir l’Estatut d’autonomia de Catalunya, i que en part van ser declarats inconstitucionals pel seu caràcter unilateral. Aquestes previsions estatutàries s’havien inspirat en gran mesura en els principis seguits a Alemanya, com el de prohibició d’anivellament total o el d’ "ordinalitat”, motiu pel qual la segona part de l’article analitza la normativa d’aquest país i la seva interpretació per la jurisprudència constitucional. En general, la situació existent actualment a tots dos estats no és tan dispar, ja que, malgrat la sentència del Tribunal Constitucional sobre l’Estatut, el sistema de finançament aprovat el 2009 continua aplicant aquests principis. Tanmateix, a diferència del que succeeix a Alemanya, a Espanya destaca l’asimetria provocada per l’escassa contribució dels territoris forals a la solidaritat, aspecte que resulta injustificat i que per tant s’hauria de corregir.This article analyses the application of the constitutional principle of fiscal equalization in Spain and Germany focusing on the issue of its limits. To begin with, the Spanish case is presented, including both the autonomous communities under the common system and the Basque Country and Navarre, and paying particular attention to the limits to solidarity which had been foreseen by the Statute of Autonomy of Catalonia and which have been partly declared unconstitutional due to their unilateral character. Given that these statutory provisions had been inspired to a large extent by the principles followed in Germany, such as the prohibition of a complete fiscal equalization, the second part of the article analyses the legal framework of this country and its interpretation in the constitutional case law. In general, the current situation in both States is not so different, given that, despite the decision of the Spanish Constitutional Court on the Statute of Autonomy of Catalonia, the general financing system of 2009 still applies these principles. Catalonia, the general financing system of 2009 still applies these principles. However, in contrast to the situation in Germany, a notable difference is the asymmetry which exists in Spain due to the limited contribution of the Basque Country and Navarre to fiscal equalization transfers, which is unjustified and therefore should be corrected.El presente estudio analiza la aplicación del principio constitucional de solidaridad interterritorial en España y en Alemania centrándose en la cuestión de sus límites. Inicialmente se presenta el caso de España, incluyendo tanto las comunidades autónomas de régimen común como las forales y prestando especial atención a los límites a la solidaridad que introdujo el Estatuto de Autonomía de Cataluña y que en parte fueron declarados inconstitucionales por su carácter unilateral. Tales previsiones estatutarias se habían inspirado en gran medida en los principios seguidos en Alemania, como el de prohibición de nivelación total o el de “ordinalidad”, por lo que la segunda parte del artículo analiza la normativa de este país y su interpretación por la jurisprudencia constitucional. En general, la situación existente actualmente en ambos Estados no es tan dispar, ya que, a pesar de la sentencia del Tribunal Constitucional sobre el Estatuto, el sistema de financiación aprobado en 2009 continúa aplicando estos principios. Sin embargo, a diferencia de lo que sucede en Alemania, en España destaca la asimetría provocada por la escasa contribución de los territorios forales a la solidaridad, aspecto que resulta injustificado y que por lo tanto debería corregirse

Organization of the Streptococcal ExPortal and its Interaction with Cationic Antimicrobial Peptides

Streptococcus pyogenes and other Gram-positive pathogens are highly dependent on secreted virulence proteins for their ability to colonize a host and evade the immune effectors that act on pathogens to prevent this. Unlike eukaryotes and Gram-negative bacteria, all Gram-positive pathogens lack a cellular compartment dedicated to folding and processing secreted proteins once they have been translocated across the cytoplasmic membrane. S. pyogenes and other Gram-positive organisms overcome this challenge by clustering the secretory translocons at a defined anionic lipid microdomain of the cytoplasmic membrane that is enriched for accessory factors needed for protein biogenesis, referred to as the ExPortal. The manner in which S. pyogenes achieves and maintains spatial coordination of the factors that constitute the ExPortal is not understood. Given the importance of secreted virulence proteins to streptococcal pathogenicity, the ExPortal is an attractive target for the development of therapeutics that can efficiently counter streptococcal infections. I investigated the interaction of cationic antimicrobial peptides with the streptococcal ExPortal to provide insights into how this secretory organelle is organized and how it may be targeted by this mechanism of innate immunity. Cationinc antimicrobial peptides: CAPs) targeted the anionic lipid microdomain of the ExPortal. Traditionally regarded as membrane permeabilizing compounds, CAPs interacted with the streptococcal membrane at concentrations that did not porate the membrane. Rather, exposure of S. pyogenes to sub-lethal CAP concentrations resulted in concomitant redistribution of anionic lipids, translocons and accessory factors to peripheral regions of the membrane. In addition, CAPs inhibited secretion of important virulence proteins, including the pathogenically relevant SpeB protease and Streptolysin O: SLO) cytolysin. One of the CAPs investigated also targets the lipid II precursor of extracellular peptidoglycan, suggesting the influence of CAPs on ExPortal organization extended beyond their affinity for negatively charged membrane lipids and that the streptococcal cell wall is involved in organizing the ExPortal. Removal of extracellular peptidoglycan also resulted in redistribution of anionic lipids and ExPortal protein, indicating the cell wall is required for maintaining proper localization of both lipid and protein components of the ExPortal. Exposure of streptococci to lantibiotics that preferentially bind and sequester lipid II in the cytoplasmic membrane disrupted ExPortal organization and secretory function in a manner similar to CAP activity. Given that both CAPs and lantibiotics target lipid components of the cytoplasmic membrane, it appears that lipid segregation in the membrane is central to organization of the ExPortal. Establishment or maintenance of this lipid segregation could involve interaction with petidoglycan synthesis in the streptococcal membrane, as two membrane-localized synthetic enzymes, one integral: MraY), the other membrane-associated: MurN), that are required for lipid II production are localized in the same anionic lipid microdomain to where secretory translocons of the ExPortal are targeted to. This provides a potential model for the mechanism(s) organizing the ExPortal. Cytoskeletal proteins and cell wall biogenesis components which are observed to interact with cytoplasmic membrane structures to organize membrane localized processes required for cell growth and division influence the segregation of anionic lipids in the membrane, and by extension, where and how the ExPortal is organized. Testing of this model by genetic and molecular approaches that target components of cell division and peptidoglycan will provide both further insights into how Gram-positive bacteria coordinate protein biogenesis with secretion as well as reveal novel potential targets for the development of effective therapeutics against pathogens like S. pyogenes

Enantioselective Organocatalytic Diels-Alder Trapping of Photochemically Generated Hydroxy-o-Quinodimethanes

The photoenolization/Diels-Alder strategy offers straightforward access to synthetically valuable benzannulated carbocyclic products. This historical light-triggered process has never before succumbed to efforts to develop an enantioselective catalytic approach. Herein, we demonstrate how asymmetric organocatalysis provides simple yet effective catalytic tools to intercept photochemically generated hydroxy-o-quinodimethanes with high stereoselectivity. We used a chiral organic catalyst, derived from natural cinchona alkaloids, to activate maleimides toward highly stereoselective Diels-Alder reactions. An unconventional mechanism of stereocontrol is operative, wherein the organocatalyst is actively involved in both the photochemical pathway, by leveraging the formation of the reactive photoenol, and the stereoselectivity-defining event