An advanced symbolic analyzer for the automatic generation of analog circuit design equations

A tool for symbolic analysis of analog integrated circuits is presented featuring accurate simplification, pole/zero extraction, and tools for parametric AC circuit characterization. The program, called ASAP, uses signal flowgraph methods and has been written in C for portability. In its current version, ASAP is able to deal with the complexity levels arising in typical analog building blocks when described by device-level models. The ASAP inputs and outputs, the architecture, and the graphical interface are discussed

Tool for fast mismatch analysis of analog circuits

A tool is presented that evaluates statistical deviations in performance characteristics of analog circuits, starting from statistical deviations in the technological parameters of MOS transistors. Performance is demonstrated via the analysis of a Miller OTA in two different configurations and a linearized CMOS transconductor. The CPU time is reduced by a factor of 25 to 90 with respect to conventional Monte Carlo simulation, while maintaining similar accuracy in the computations

Continuous-time cascaded ΣΔ modulators for VDSL: A comparative study

This paper describes new cascaded continuous-time ΣΔ modulators intended to cope with very high-rate digital subscriber line specifications, i.e 12-bit resolution within a 20-MHz signal bandwidth. These modulators have been synthesized using a new methodology that is based on the direct synthesis of the whole cascaded architecture in the continuous-time domain instead of using a discrete-to-continuous time transformation as has been done in previous approaches. This method allows to place the zeroes/poles of the loop-filter transfer function in an optimal way and to reduce the number of analog components, namely, transconductors and/or amplifiers, resistors, capacitors and digital-to-analog converters. This leads to more efficient topologies in terms of circuitry complexity, power consumption and robustness with respect to circuit non-idealities. A comparison study of the synthesized architectures is done considering their sensitivity to most critical circuit error mechanisms. Time-domain behavioral simulations are shown to validate the presented approach.Ministerio de Educación y Ciencia TEC2004-01752/MI

A design tool for high-resolution high-frequency cascade continuous- time Σ∆ modulators

Event: Microtechnologies for the New Millennium, 2007, Maspalomas, Gran Canaria, SpainThis paper introduces a CAD methodology to assist the de signer in the implementation of continuous-time (CT) cas- cade Σ∆ modulators. The salient features of this methodology ar e: (a) flexible behavioral modeling for optimum accuracy- efficiency trade-offs at different stages of the top-down synthesis process; (b) direct synthesis in the continuous-time domain for minimum circuit complexity and sensitivity; a nd (c) mixed knowledge-based and optimization-based architec- tural exploration and specification transmission for enhanced circuit performance. The applicability of this methodology will be illustrated via the design of a 12 bit 20 MHz CT Σ∆ modulator in a 1.2V 130nm CMOS technology.Ministerio de Ciencia y Educación TEC2004-01752/MICMinisterio de Industria, Turismo y Comercio FIT-330100-2006-134 SPIRIT Projec

Global design of analog cells using statistical optimization techniques

We present a methodology for automated sizing of analog cells using statistical optimization in a simulation based approach. This methodology enables us to design complex analog cells from scratch within reasonable CPU time. Three different specification types are covered: strong constraints on the electrical performance of the cells, weak constraints on this performance, and design objectives. A mathematical cost function is proposed and a bunch of heuristics is given to increase accuracy and reduce CPU time to minimize the cost function. A technique is also presented to yield designs with reduced variability in the performance parameters, under random variations of the transistor technological parameters. Several CMOS analog cells with complexity levels up to 48 transistors are designed for illustration. Measurements from fabricated prototypes demonstrate the suitability of the proposed methodology

Relationship between shoulder pain and skin temperature measured by infrared thermography in a wheelchair propulsion test

Wheelchair Users (WCUs) depend on their upper extremities for their daily living. Therefore, it is not unusual to find that shoulder pain (SP) is a problem for WCUs and reduces their participation in sport and leisure activities

Characterisation of the National Network of Silos and Granaries in Castilla y León, Spain: A Case Study

[EN] In 1995, Spain’s National Network of Silos and Granaries was divided into a basic network and a secondary network. Of the total storage units identified, 541 are vertical units or silos forming part of the secondary network. Unlike the silos of the basic network, many of the secondary network silos, which were primarily reception units sited near the areas where the grain was grown, have been repurposed. This article describes a methodology developed to inventory silos based on their general features, construction and technological facilities, and its application to the 123 silos in the secondary network in the Spanish region of Castilla y León. The exercise was conducted in conjunction with a socioeconomic analysis of the communities where the silos are located. All the silos studied are located in the most productive areas and close to farms, have small storage capacities and include all but one silo typology, the transition macro-silo. Some are still used for grain storage, whilst others have been converted into multi-purpose warehouses, gymnasiums, community centres or other specialised facilities. Ideas for silo repurposing implemented in other regions of Spain and other countries might well be applied in Castilla y León. In addition, this methodology has proved useful to identify proposals that are viable in the more highly populated communities.S

Cyclodextrin-scaffolded glycotransporters for gene delivery

Abstract: Conventional drugs consist of a formulation of a bioactive species and a carrier, the former accounting for most of the sophistication of the design. In the case of biomolecular drugs, however, the role of the carrier becomes decisive in enabling the load to reach its target to carry out its designed therapeutic function. Thus, the clinical success of gene therapy, where the active principles are nucleic acids, critically depends on the use of efficient and safe delivery systems. Carbohydrates have proven particularly useful in this regard. Glycocoating, similarly to poly(ethylene)glycol (PEG)-coating (pegylation), can stabilize colloidal aggregates by improving solvation and preventing nonspecific interactions, for example, with serum proteins. Moreover, glycoconjugates can drive specific recognition and receptor-mediated internalization in target cells. Actually, the inherent flexibility of carbohydrate and glycoconjugate chemistry has greatly contributed to enlarging the range of functional materials that can be rationally conceived for gene delivery. Herein, this is illustrated with selected examples that focus on controlling the architectural parameters of the vectors to make them suitable for structure¿activity relationship (SAR) and optimization studies. The members of the cyclomaltooligosaccharide (cyclodextrin, CD) family will be the central actors of the story.Peer Reviewe

Pharmacological chaperone therapy for Gaucher disease: A patent review

Introduction: Mutations in the gene encoding for acid β-glucosidase (β-glucocerebrosidase, GlcCerase) are seen in Gaucher disease (GD), which give rise to significant protein misfolding effects and result in progressive accumulation of glucosyl ceramide. The main treatment for GD is enzyme replacement therapy (ERT). The iminosugar glycosidase inhibitor N-(n-butyl)-1-deoxynojirimycin (miglustat, Zavesca™) is used in a second treatment modality known as substrate reduction therapy. At the beginning of the 21st century, a third therapeutic paradigm was launched, namely, pharmacological chaperone therapy (PCT). This therapeutic strategy relies on the capability of such inhibitors to promote the correct folding and stabilize mutant forms of lysosomal enzymes, such as GlcCerase, as they pass through the secretory pathway. Areas covered: This review summarizes the different approaches used to implement the concept of PCT for GD. It discusses the relevant research, patents and patent applications filed in the last decade. Expert opinion: While the significance of PCT remains a matter of debate, the great interest gathered regarding it in a relatively few years reflects its broad potential scope, well beyond GD. The fact that pharmacological chaperones can be designed to cross the blood brain barrier (BBB) make them candidates for the treatment of neuronopathic forms of GD that are not responsive to ERT. Combined therapies offer even broader possibilities that deserve to be fully explored.Ministerio de Ciencia e Innovación CTQ2007-61180/PPQ, SAF2010-15670Junta de Andalucía P08-FQM-0371