CMOS Sigma-Delta Converters Rosa, Jos? M. de la; R?o, Roc?o del
2013, 2013-05-06T00:00:00, 2013-03-13, 2013-02-25
eBook
A comprehensive overview of Sigma-Delta Analog-to-Digital Converters (ADCs) and a practical guide to their design in nano-scale CMOS for optimal performance.This book presents a systematic and ...comprehensive compilation of sigma-delta converter operating principles, the new advances in architectures and circuits, design methodologies and practical considerations minus; going from system-level specifications to silicon integration, packaging and measurements, with emphasis on nanometer CMOS implementation. The book emphasizes practical design issues – from high-level behavioural modelling in MATLAB/SIMULINK, to circuit-level implementation in Cadence Design FrameWork II. As well as being a comprehensive reference to the theory, the book is also unique in that it gives special importance on practical issues, giving a detailed description of the different steps that constitute the whole design flow of sigma-delta ADCs. The book begins with an introductory survey of sigma-delta modulators, their fundamentals architectures and synthesis methods covered in Chapter 1. In Chapter 2, the effect of main circuit error mechanisms is analysed, providing the necessary understanding of the main practical issues affecting the performance of sigma-delta modulators. The knowledge derived from the first two chapters is presented in the book as an essential part of the systematic top-down/bottom-up synthesis methodology of sigma-delta modulators described in Chapter 3, where a time-domain behavioural simulator named SIMSIDES is described and applied to the high-level design and verification of sigma-delta ADCs. Chapter 4 moves farther down from system-level to the circuit and physical level, providing a number of design recommendations and practical recipes to complete the design flow of sigma-delta modulators. To conclude the book, Chapter 5 gives an overview of the state-of-the-art sigma-delta ADCs, which are exhaustively analysed in order to extract practical design guidelines and to identify the incoming trends, design challenges as well as practical solutions proposed by cutting-edge designs.Offers a complete survey of sigma-delta modulator architectures from fundamentals to state-of-the art topologies, considering both switched-capacitor and continuous-time circuit implementationsGives a systematic analysis and practical design guide of sigma-delta modulators, from a top-down/bottom-up perspective, including mathematical models and analytical procedures, behavioural modeling in MATLAB/SIMULINK, macromodeling, and circuit-level implementation in Cadence Design FrameWork II, chip prototyping, and experimental characterization.Systematic compilation of cutting-edge sigma-delta modulatorsComplete description of SIMSIDES, a time-domain behavioural simulator implemented in MATLAB/SIMULINKPlenty of examples, case studies, and simulation test benches, covering the different stages of the design flow of sigma-delta modulatorsA number of electronic resources, including SIMSIDES, the statistical data used in the state-of-the-art survey, as well as many design examples and test benches are hosted on a companion websiteEssential reading for Researchers and electronics engineering practitioners interested in the design of high-performance data converters integrated in nanometer CMOS technologies; mixed-signal designers.
Epigenetic alterations have been suggested to be associated with obesity and related metabolic disorders. Here we examined the correlation between obesity and insulin resistance with the methylation ...frequency of the leptin (LEP) and adiponectin (ADIPOQ) promoters in obese adolescents with the aim to identify epigenetic markers that might be used as tools to predict and follow up the physiological alterations associated with the development of the metabolic syndrome.
One hundred and six adolescents were recruited and classified according to body mass index and homeostasis model of assessment-insulin resistance index. The circulating concentrations of leptin, adiponectin and of several metabolic markers of obesity and insulin resistance were determined by standard methods. The methylation frequency of the LEP and ADIPOQ promoters was determined by methylation-specific PCR (MS-PCR) in DNA obtained from peripheral blood samples.
Obese adolescents without insulin resistance showed higher and lower circulating levels of, respectively, leptin and adiponectin along with increased plasmatic concentrations of insulin and triglycerides. They also exhibited the same methylation frequency than lean subjects of the CpG sites located at -51 and -31 nt relative to the transcription start site of the LEP gene. However, the methylation frequency of these nucleotides dropped markedly in obese adolescents with insulin resistance. We found the same inverse relationship between the combined presence of obesity and insulin resistance and the methylation frequency of the CpG site located at -283 nt relative to the start site of the ADIPOQ promoter.
These observations sustain the hypothesis that epigenetic modifications might underpin the development of obesity and related metabolic disorders. They also validate the use of blood leukocytes and MS-PCR as a reliable and affordable methodology for the identification of epigenetic modifications that could be used as molecular markers to predict and follow up the physiological changes associated with obesity and insulin resistance.
Introducción: el estudio analizó (a) las diferencias entre madres y padres en sus actividades matemáticas en el hogar y en otros factores del ambiente matemático (actitudes, ansiedad, creencias y ...expectativas matemáticas) y (b) la asociación entre los factores del ambiente matemático y las actividades matemáticas en el hogar. Método: participaron 266 familias de niños y niñas chilenos de primer a tercer grado de primaria (edad promedio = 93.35 meses, DE = 11.45 meses). Ambos padres contestaron un cuestionario sobre matemáticas en el hogar. Resultados: las madres reportaron realizar actividades matemáticas con mayor frecuencia que los padres. Análisis de ecuaciones estructurales mostraron que las actividades matemáticas realizadas por los padres se relacionaron con sus creencias, actitudes y expectativas matemáticas; mientras que las de las madres se relacionaron con sus creencias, actitudes y género de los niños. Conclusiones: los hallazgos aportan a la comprensión del ambiente matemático en el hogar.
We analyze the onset and initial expansion of the 2018 Martian Global Dust Storm (GDS 2018) using ground‐based images in the visual range. This is the first case of a confirmed GDS initiating in the ...Northern Hemisphere. A dusty area extending about 1.4×105 km2 and centered at latitude +31.7°±1.8° and west longitude 18°±5°W in Acidalia Planitia was captured on 30 and 31 May 2018 (Ls = 184.9°). From 1 to 8 June, daily image series showed the storm expanding southward along the Acidalia corridor with velocities of 5 m/s and simultaneously progressing eastward and westward with horizontal velocities ranging from 5 to 40 m/s. By 8 June the dust reached latitude ‐55° and later penetrated in the South polar region, whereas in the North the dust progression stopped at latitude approximately +46°. We compare the onset and expansion stage of this GDS with the previous confirmed storms.
Key Points
May‐June 2018 ground‐based images show the onset and early evolution of a Martian Global Dust Storm (GDS)
The outbreak took place at location (North hemisphere) and time (solar longitude 184.9°) unusual for most GDSs
The expansion involved horizontal velocities in all directions in the range 5‐40 m/s
Esta contribución completa la entrevista con Antonio Gilman Guillén, cuya primera parte se publicó en Trabajos de Prehistoria 77 (1). Gilman es Profesor Emérito de la California State ...University-Northridge (EE. UU.), fue director de Trabajos de Prehistoria (2015-2018) y ha dedicado la mayor parte de su trabajo a la Prehistoria Reciente de la península ibérica. Los temas tratados en esta segunda entrega se agrupan en dos bloques. En el primero de ellos se plasman sus reflexiones sobre la experiencia de su relación con la Arqueología española. Se repasan sus opiniones sobre la arqueología tradicional bajo el franquismo, el proceso de modernización, con sus rasgos específicos, y las tendencias recientes y los cambios más relevantes en el registro arqueológico. Estas cuestiones se abordan desde su experiencia como investigador extranjero en España y sus propias contribuciones científicas. También se presta atención a su actividad como recopilador crítico de la cronología radiocarbónica ibérica. El segundo bloque se dedica al contexto intelectual de su práctica arqueológica. Se discuten sus raíces en la segunda generación de la New Archaeology y las aportaciones del marxismo a la consolidación de un funcionalismo crítico con sentido histórico y sus referentes teóricos en la obra de autores como Childe, Adams o Wolf. Se examinan en este contexto sus puntos de vista en relación con algunos de los temas que definen el campo de su trabajo como prehistoriador: los problemas del origen de la desigualdad social y el Estado, las formas políticas de las “sociedades intermedias” y la “Revolución del Paleolítico Superior”. Se hace referencia también a los desafíos que presenta el desarrollo de la “ciencia arqueológica” y particularmente la paleogenética, y su influencia en el retorno de la arqueología histórico-cultural y difusionista. Finalmente, se valora la contraposición entre las tradiciones del historicismo europeo y la Arqueología antropológica norteamericana y el momento actual de esta última.
ABSTRACT
Low temperature is an environmental stress that affects crop production and quality and regulates the expression of many genes, and the level of a number of proteins and metabolites. Using ...leaves from pepper (Capsicum annum L.) plants exposed to low temperature (8 °C) for different time periods (1 to 3 d), several key components of the metabolism of reactive nitrogen and oxygen species (RNS and ROS, respectively) were analysed. After 24 h of exposure at 8 °C, pepper plants exhibited visible symptoms characterized by flaccidity of stems and leaves. This was accompanied by significant changes in the metabolism of RNS and ROS with an increase of both protein tyrosine nitration (NO2‐Tyr) and lipid peroxidation, indicating that low temperature induces nitrosative and oxidative stress. During the second and third days at low temperature, pepper plants underwent cold acclimation by adjusting their antioxidant metabolism and reverting the observed nitrosative and oxidative stress. In this process, the levels of the soluble non‐enzymatic antioxidants ascorbate and glutathione, and the activity of the main NADPH‐generating dehydrogenases were significantly induced. This suggests that ascorbate, glutathione and the NADPH‐generating dehydrogenases have a role in the process of cold acclimation through their effect on the redox state of the cell.
Low temperature is an environmental stress that affects plants growth and consequently crop production and quality. Pepper plants are a worldwide consumable vegetables affected for this stress. In this work it is studied how low temperature influences the metabolism of reactive oxygen and nitrogen species as well as the redox state being the soluble antioxidants (ascorbate and glutathione) and the NADPH‐generating dehydrogenases key components in the process of cold acclimation.
Los parásitos zoonóticos caninos han sido reconocidos como un importante problema de salud pública, especialmente en países en desarrollo con condiciones socioambientales vulnerables. En el contexto ...de “Una Salud” el objetivo de este trabajo fue evaluar el dominio animal mediante la evaluación de enteroparásitos zoonóticos caninos asociados a un Índice de Vulnerabilidad Parasitaria (IVP) en comunidades periféricas (CP) y urbanas (CU) de la ciudad de Mar del Plata. El IPV fue elaborado en un trabajo anterior como un indicador de vulnerabilidad de enfermedades parasitarias, en relación a las condiciones socioambientales relevadas en las comunidades sobre las siguientes dimensiones: vivienda, saneamiento, higiene, educación y trabajo. Se realizó un estudio coproparasitológico para establecer la presencia y la riqueza de parásitos caninos en el ambiente de ambas comunidades. La CP evidenció hogares con mayor número medio de muestras fecales caninas (MFC) con parásitos que la CU, mostrando también la mayor riqueza específica parasitaria con helmintos y protozoos. Las frecuencias de Ancylostomids, Capillariids y Toxocara canis fueron mayores en la CP, pero las frecuencias de Trichuris vulpis y la prueba de coproantígeno positivo para detectar Echinococcus granulosus, fueron similares entre comunidades. La CP evidenció asociación de variables relacionadas con la tenencia de perros (ausencia de atención veterinaria y desparasitación no adecuada), con la presencia de MFC con parásitos y la prueba de coproantígeno positiva. Las familias con IVP medio y alto de la CP evidenciaron una fuerte asociación con la presencia de MFC con parásitos y también con alta riqueza parasitaria, mientras que las familias de la CU con IVP bajo evidenciaron MFC sin parásitos. Estos resultados revelaron un escenario vulnerable para la permanencia y la transmisión de parásitos zoonóticos caninos en la mayoría de las familias de la CP, destacando el valor de las características socio ambientales como predictores de parasitosis
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•Seaweeds are important sources of carbohydrates for the production of biofuels.•Pretreatment is the key step for the development of seaweed biorefinery.•Emerging and green ...technologies can contribute to feasibility of seaweed biorefinery.•Wastes from hydrocolloid industry are interesting alternative for biofuels production.
Concerns about fossil fuels depletion has led to seek for new sources of energy. The use of marine biomass (seaweed) to produce biofuels presents widely recognized advantages over terrestrial biomasses such as higher production ratio, higher photosynthetic efficiency or carbon-neutral emissions. In here, interesting seaweed sources as a whole or as a residue from seaweed processing industries for biofuel production were identified and their diverse composition and availability compiled. In addition, the pretreatments used for seaweed fractionation were thoroughly revised as this step is pivotal in a seaweed biorefinery for integral biomass valorization and for enabling biomass-to-biofuel economic feasibility processes. Traditional and emerging technologies were revised, with particular emphasis on green technologies, relating pretreatment not only with the type of biomass but also with the final target product(s) and yields. Current hurdles of marine biomass-to-biofuel processes were pinpointed and discussed and future perspectives on the development of these processes given.
Diseases caused by the fungus Sclerotinia sclerotiorum are managed mainly through fungicide applications in canola and dry bean. Accurate estimation of the risk of disease development on these crops ...could help farmers make spraying decisions. Five machine learning (ML) models were evaluated in classification and regression modes for predicting disease establishment under different air temperatures and leaf wetness duration conditions. Model algorithms were trained and tested using 20-fold cross validation. Correspondence between predicted and observed values were measured using Cohen's Kappa (classification) and Lin's concordance coefficients (regression). The artificial neural network (ANN) algorithms had average accuracies ≥ 89% (classification) and R
≥ 88% (regression) on canola and dry bean and their correspondence agreements were ≥ 0.83, which is considered substantial to almost perfect. In contrast, logistic regression algorithms had accuracies of 88% for dry bean and 78% for canola; other models were similarly inconsistent. Implementation of ANN models in disease warning systems could help farmers with spraying decisions. At the same time, these models provide insights on temperature and leaf wetness requirements for development of S. sclerotiorum diseases in these crops. Results of this study show the potential of ML models as tools for epidemiological studies on other pathosystems.
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