bluuebunny/crossref_metadata_2025 huggingface dataset:
Development and design of wave SC filters
Authors: Limperis A. , Haritantis I.
Published: July 2007

A direct z‐domain simulation ofLCladder and unit‐element filters by means of wave SC circuits is presented. the development of a wave SC circuit is achieved by interconnecting a limited number of basic SC building blocks. the derived circuits are fully parasitic‐free, symmetric and can be optimally designed for dynamic range maximization and capacitance area minimization. the number of operational amplifiers in the simulated unit‐element filters is essentially low in comparison to earlier presented parasitic‐insensitive wave SC filters and to leap‐frog‐type SC filters. Four‐ and two‐phase multiplexed simulatedLCRfilters can be developed. Bilinear s‐z transformation applies for all the circuits; thus the design is exact and there is no requirement for a high clock frequency. Filters with transmission zeros can be developed. the simulated responses of various types of filters are in good agreement with the theory. Detailed examples of different designs are given.
Efficient performance function interpolation scheme and its application to statistical circuit design
Authors: Biernacki R. M. , Styblinski M. A.
Published: July 2007

A concept of ‘maximally’ flat polynomial interpolation of circuit responses (or performance functions) is proposed, developed and exploited. This kind of simple approximation of circuit behaviour proves extremely useful for Monte Carlo statistical yield estimation and optimization. Application of the resulting interpolating polynomials may substantially reduce the number of actual, time‐consuming circuit analyses. Results of all available circuit analyses can be utilized to construct the interpolating polynomials, even if their number is not sufficient for a full unique quadratic or higher‐order interpolation. This is accomplished by selecting the maximally flat interpolation in which all higher‐order‐term coefficients are minimized in the least squares sense. More importantly, a low‐cost updating of the interpolating polynomials is developed in order to accommodate the results of additional circuit simulations as they become available. Examples of this approximation of circuit responses as well as its application to yield estimation and optimization are shown.
An optimal algorithm for rectilinear steiner trees for channels with obstacles
Authors: Chiang Charles , Sarrafzadeh Majid , Wong C. K.
Published: July 2007

The channel rectilinear Steiner tree problem is to construct an optimal rectilinear Steiner tree interconnectingnterminals on the upper shore and the lower shore of a channel without crossing any obstacles inside the channel. However, intersecting boundaries of obstacles is allowed. We present an algorithm that computes an optimal channel rectilinear Steiner tree inO(F1(k)n + F2(k))time, wherekis the number of obstacles inside the channel andF1andF2are exponential functions ofk. For any constantkthe proposed algorithm runs inO(n)time.
The Parametric Yield Enhancement of Integrated Circuits
Authors: Singha Miran , Spence Robert
Published: July 2007

Even where a satisfactory circuit design has been achieved, it is often the case that, owing to variations in the manufacturing process, some of the samples of a mass‐produced circuit will violate the specifications on performance so that the manufacturing yield is less than 100%. Such an undesirable effect can, however, be minimized or even eliminated by redesign of the circuit to the extent of changing parameter values while retaining the original circuit topology. For discrete component circuits algorithms are available to achieve such redesign. the special characteristics of integrated circuits, however, are such that these methods are unsuitable as they stand. Two new algorithms for handling the yield enhancement of integrated circuits are described and their successful application is illustrated in the context of two‐stage CMOS op amps.
Transformation of the transfer function variables of the singularn‐dimensional roesser model
Authors: Galkowski Krzysztof
Published: July 2007

A singular Roesser model is presented for a non‐causaln‐dimensional (n‐D) system described by ann‐D transfer function with non‐monic denominator. Transformations of the transfer function variables (inversion, multivariable bilinear transformation) have been used to transform the given polynomial to monic form. These transformations are also discussed in state‐space description terms. Additionally, the matrixQwhich relates the coefficients vector of the transformed polynomial to that of the original one is obtained usingn‐way matrix methods.
A method for the investigation of high‐order two‐frequency asynchronous oscillators
Authors: Calandra Enrico F. , Sommariva Antonino M.
Published: July 2007

A general method for analysing asynchronous high‐order two‐frequency oscillators is presented. the oscillator model is made up of a GC non‐linear parallel group embedded in a linear lumped time‐invariant network of any order. the approach devised rests on the identification of a pair of narrow‐band impedance operators which permit one to derive first‐approximation steady state and dynamic equations in the phasor domain—as well as stability criteria—in a simple and expressive manner. Previous results from averaging and perturbation treatments on fourth‐order asynchronous oscillators are shown to be obtainable from this theory as particular cases. the sixth‐order oscillator chosen as an application example shows that computational efficiency and accuracy are among the features of the method.
Scheduling Algorithms For Hierarchical Data Control Flow Graphs
Authors: Potkonjak Miodrag , Rabaey Jan M.
Published: July 2007

New algorithms for the allocation, assignment and scheduling of a hierarchical data control flow graph (DCFG) with imposed timing constraints are presented. the hierarchical allocation environment performs a probabilistic search through the design space and converges towards a final solution by iteratively calling and interchanging resource utilisation information with the assignment and scheduling subroutines.

The allocation, assignment and scheduling problem is posed in a such a way that the specific costs of all hardware elements are taken into account and simultaneously addressed. the proposed algorithms have novel constructive and rejectionless iterative improvement probabilistic components.

The effectiveness of the algorithms is demonstrated with the aid of extensive experimental results. In addition to the standard benchmarks, we have studied a broad class of test examples of a very diverse nature, thus covering the global design space. We also discuss how min‐bound estimations are used to more easily and realistically assess the quality of the allocation, assignment and scheduling algorithms.
A prototype tool for the design‐oriented symbolic analysis of analogue circuits
Authors: Dorel F. , Declercq M.
Published: July 2007

New methodologies for the ‘design‐oriented’ symbolic analysis of analogue circuits are presented. the objective of this analysis is to obtain results that will give more insight into the circuit behaviour. the feature of the presented methods is to allow the network function to be stated in several parts, with an eventual hierarchical dependence on each other, but without loss of interpretability.

Several methods are combined. the first one consists of a rule‐based algorithm for network reduction which allows significant simplification before the main analysis is performed. Initially, simple models can be used, since the effects of parasitic elements can be computed afterwards at little CPU expense, thanks to the implementation of the extra element theorem.3the network is divided into blocks by a simple decomposition algorithm. Each block is analysed and the network function is next calculated.

To reduce the size of the calculated expressions, the symbolic calculator uses the concept of ‘correction factor’, based on a comparison between the orders of magnitude of the symbolic terms. A PROLOG prototype tool has been written in order to validate these methods. A simple two‐stage amplifier is taken as an example. the solution contains 11 products, to be compared with the 174 that would give a direct topological analysis.
Automation of the ic layout of continuous‐time transconductance‐capacitor filters
Authors: Daasch W. Robert , Wedlake Martine , Schaumann Rolf , Wu Pan
Published: July 2007

To exploit the increased circuit density available in current technologies for continuous‐time (c‐t) systems, it is proposed to extend the range of analogue design automation to the larger c‐t subsystems, specifically filters, commonly found in communications, mass storage devices and other interfaces to real‐world signals. the synthesis is based onLCladder simulation using only transconductances and grounded capacitors (TGC). the method retains many of the characteristics of digital design automation and therefore allows a direct mapping of these techniques. the TGC approach is shown to require a minimum of component types which are ideally suited to integration in MOS, bipolar or GaAs technologies. A simple example for the automation of c‐t filter designs as well as results of CMOS c‐t filters are included to demonstrate the viability of this approach. Related and equally important areas addressed are tuning, compensation for parasitics and scaling.
Computer‐aided manipulation of mason's formula and its applications
Authors: Wang Chi‐Hsu
Published: July 2007

This paper presents a new method to determine the symbolic gain of a linear system via Mason's formula. A combined searching algorithm based on the breadth‐first and depth‐first searching algorithms in a directed graph is devised to find the forward paths and loops in the linear system. Mason's formula is then determined via touching‐non‐touching matches of forward paths and loops in the system. A SPICE‐like system Description language (SDL) is also proposed to describe the linear system so that this new algorithm can be put into execution in a computer language. In comparison with other approaches, this method is more straightforward and needs no complicated matrix operations. the completeness of this new method had already been guaranteed by Mason's original formula. It is also believed that Mason's formula has a new interpretation through this new approach.
On symbolic dynamics of a chaotic second‐order digital filter
Authors: Galias Zbigniew , Ogorzalek Maciej J.
Published: July 2007

This paper presents a contribution to the symbolic analysis of fractal patterns exhibited by a second‐order digital filter with modular adder overflow characteristic. We use symbolic dynamics for the analysis of phenomena encountered in the system. We present several new results concerning the existence of admissible sequences for periodic orbits in the filter. an efficient computational algorithm based on rigorous mathematical results presented in the paper enabled us to calculate sequences with long periods, thus allowing deeper understanding of the underlying mechanisms of complex behaviour encountered in the filter.
On algorithms in the parallel design of logic and layout of circuits with functional blocks
Authors: Szolgay Peter
Published: July 2007

Some algorithms in an experimental design methodology for circuits with combinatorial logic blocks are described in which the circuit schematics and the layout of the blocks are designed in parallel. A combinational circuit is represented by three parallel descriptions, namely the functional (truth table), the incidence (connections) and the one‐dimensional layout. to support this design method, new types of algorithms have been developed for the component extraction and interconnection phases, enabling the interactive design activity of ‘twin’ designers. the two‐dimensional layout—which is a fourth representation—of the whole circuit is generated using the one‐dimensional layout model.
Discrete‐time cellular neural networks
Authors: Harrer Hubert , Nossek Josef A.
Published: July 2007

A network structure called a discrete‐time cellular neural network is introduced. It is derived from cellular neural networks and feedback threshold networks. the architecture is discussed and its advantages are presented. Convergence is proved for a large class of templates and applications are given for the following image‐processing tasks: linear thresholding, connected component detection, hole filling, concentric contouring, increasing and decreasing objects step by step, searching for objects with minimal distance, and oscillation.
Cellular neural networks: Theory and circuit design
Authors: Nossek Josef A. , Seiler Gerhard , Roska Tamás , Chua Leon O.
Published: July 2007

Cellular neural networks or CNNs are a novel neural network architecture introduced by Chua and Yang which is very general and flexible, has some important properties desirable for design applications and can be efficiently implemented on custom hardware based on analogue VLSI technology.

In this paper an abstract normalized definition of cellular neural networks with arbitrary interconnection topology is given. Instead of stability, the property of convergence is found to be of central importance: large classes of convergent CNNs in practice always asymptotically approach some stable equilibrium where each component of the corresponding output is binary‐valued.

A highly efficient CMOS‐compatible CNN circuit architecture is then presented where a basic cell consists of only two fully differential op amps, two capacitors and several MOSFETs, while a variable interconnection weight is realized with only four MOSFETs. Since all these elements are standard components in the current analogue IC technology and since all network functions are implemented directly on the device level, this architecture promises high cell and interconnection densities and extremely high operating speeds.
Design of high‐speed, high‐density CNNS in cmos technology
Authors: Cruz José M. , Chua Leon O.
Published: July 2007

An analogue VLSI circuit architecture for the CMOS implementation of cellular neural networks (CNNs) is presented. It is based exclusively on the use of small capacitors and operational transconductance amplifiers operating in continuous time. Integrated circuit implementations of this architecture are very well suited for processing applications requiring large array size and high speed. We describe a systematic design approach for those circuits and present the design, fabrication and testing of two chips. These chips are used for connected component detection applications and are the first working integrated circuit implementation of a CNN. They contain 2000 transistors and have been fabricated using 2 μm CMOS technology. the density is 32 cells per square millimetre of silicon and the time constant of the processing is of the order of 10−7s. Experimental results of static and dynamic tests are given, including a complete image‐processing example.
Detecting moving and standing objects using cellular neural networks
Authors: Roska T. , Boros T. , Radványi A. , Thiran P. , Chua L. O.
Published: July 2007

The general framework of motion detection based on discrete time samples of the moving image is defined. Four types of motion detection problem are studied. the simplest one is a model resembling the famous Hubel‐Wiesel experiment with a cat's retina for detecting the motion of an object having a given speed in a given direction. the most complicated case is the determination of the vertical and horizontal velocity components of a moving image.

Various cloning template sequences are proposed for detecting different types of motion. In the sampled mode the consecutive black‐and‐white snapshots are fed to the input and to the initial state nodes of the cellular neural network respectively. After the transients have decayed, the output gives the information necessary for detecting the presence or absence of a specific motion as well as for estimating the direction and magnitude of the velocity vector. In continuous mode the sampling process is eliminated by the use of delay‐type templates.

Conditions are analysed under which the detection is correct. the circuit realization of some motion detectors is discussed and the use of a programmable dual‐CNN structure is proposed.
Very‐high‐output‐impedance cascode current sources/current mirrors/transresistance stages and their applications
Authors: Zarabadil Seyed R. , Ismail Mohammed
Published: July 2007

A reconfigurable MOS/BiMOS cascode current source/transresistance stage with very high output impedance is presented in this paper. A cascode active feedback circuit has been employed to achieve such a high output impedance, which approaches the leakage resistance of a reverse‐biased junction, assuming that the MOS devices have a large channel length and do not exhibit the short‐channel effect. Through small‐signal analysis and SPICE simulation it is shown that the proposed current source/transresistance stage provides an output open‐circuit Thevinin voltage greater than 108 V. This is an increase of about four orders of magnitude as compared with the conventional cascode current source with the same output voltage range. For scaled technologies this current source/transresistance stage is shown to be ideal for practical high‐performance analogue circuit design. We have incorporated the current sources with active feedback in the output stage of a folded cascode op amp and obtained a large DC gain improvement without significantly affecting its high‐frequency/transient behaviour.
Determination of volterra transfer functions of non‐linear multiport networks
Authors: Larsen Torben
Published: July 2007

A method is presented to determine frequency domain Volterra transfer functions of non‐linear multiport networks containing non‐linear multiport subsystems (elements). the method is based on an extension of the probing method to allow arbitrary (also commensurate) frequencies. A recursively based algorithm for the determination of Volterra transfer functions of non‐linear multiport networks is derived. A computer implementation of the method in a symbolic programming language is presented. This makes it possible to determine algebraic expressions of the Volterra transfer functions. Three examples are considered.
Elimination of limit cycles in direct form digital filters using error feedback
Authors: Laakso Timo I.
Published: July 2007

The elimination of zero‐input limit cycles in direct form filter sections using either a rounding or a magnitude truncation fixed‐point quantizer is considered. the well‐known criterion of Chang is reformulated for second‐order filter sections in a more practical form using the bilinear transformation. This enables graphical interpretation and quantitative analysis of the possible error feedback solutions for different pole locations.

The synthesis of limit‐cycle‐free error feedback for second‐order filter sections is addressed in detail and several solutions are proposed. the error feedback coefficients are constrained to power‐of‐two values or to symmetric values so that the implementation is efficient, e.g. with signal processors. Different limit‐cycle‐free solutions are discussed with design examples and their round‐off noise properties are compared.

The absence of limit cycles is related to the round‐off noise properties of the filter section. the main conclusion of the paper is that when the EF coefficients are appropriately chosen, low round‐off noise and the absence of limit cycles can always be accomplished at the same time. A particularly close correlation between limit cycles and roundoff noise is demonstrated with a rounding quantizer: a limit‐cycle‐free implementation always guarantees low roundoff noise. For most complex conjugate pole locations the converse relation also holds, i.e. low round‐off noise implies the absence of limit cycles.
On the realization of OTA‐C filters
Authors: Acar C. , Anday F. , Kuntman H.
Published: July 2007

A synthesis procedure based on the signal flow graph is given for generating second‐order active filters using a minimum number of operational transconductance amplifiers and grounded capacitors. the pole quality factor and pole frequency sensitivities are studied for the proposed filters. Furthermore, the limitations on input signal amplitude are studied and a simple formula is derived for the input signal amplitude not causing clipping and slew‐rate‐limiting problems.
On the dynamic behaviour of two‐cell cellular neural networks
Authors: Civalleri Pier Paolo , Gilli Marco
Published: July 2007

A complete study of non‐linear differential equations describing two‐cell cellular neural networks (CNNs) is presented. the stability properties are investigated and the domains of attraction of the stable fixed points are determined. Also, the conditions for the existence of periodic and homoclinic cycles are stated.
Analysis of quasi‐resonant converters using a state plane method
Authors: Baha B.
Published: July 2007

In this paper a state plane method has been used to analyse flyback and buck quasi‐resonant converters (QRCs). By using the state plane method, the DC voltage conversion ratio and the voltage and current stresses of the active switch, the diode and the resonant capacitor have been derived graphically. the DC voltage conversion ratio and the current stress of the active switch have been used to design QRC circuits. A flyback QRC has been designed, simulated, built and tested. the experimental results have been found to be in good agreement with PSpice simulations.
A 2d neural network with application to solving a class of matrix equations
Authors: Fa‐Long Luo , Yan‐Da Li
Published: July 2007

This paper presents a 2D neural network with application to solving a class of matrix equations. We show both analytically and by simulations that this neural network is guaranteed to be stable and to provide results arbitrarily close to the accurate solutions of the matrix equations within an elapsed time of only a few characteristic time constants of the network. Parameters such as the interconnection strengths and bias currents of this proposed network can be obtained from the known matrices of the matrix equations without any computations.
Synthesis of complex lossless two‐ports
Authors: Scarth Gordon B. , Martens G. O.
Published: July 2007

A new synthesis algorithm is presented for the realization of a doubly terminated complex lossless two‐port from a given canonic set of scattering polynomials. the synthesis algorithm is based entirely on polynomial evaluations and thus polynomial arithmetic and routines for zero finding are not needed. the accuracy problem due to coefficient sensitivity is avoided. In particular, explicit knowledge of the intermediate polynomials is not required. the simplicity and functionality of the algorithm are based on a new representation of elementary sections given by a set of canonic parameters, namely the transmission zero of the section, the reflectance evaluated at the transmission zero and, for reciprocal sections, the return group delay evaluated at the transmission zero. A great deal of freedom is available, since transmission zeros with any multiplicity and located anywhere in the complex plane are realized independently. Also, complex networks composed exclusively of either inductors or capacitors as the dynamic elements are possible. an example is given to illustrate the robustness of the algorithm.
Finding all stable equilibria of cellular neural networks
Authors: Fajfar Iztok , Bratkovic Franc
Published: July 2007

An efficient algorithm is given for finding all stable equilibrium states of a cellular neural network. the method is based upon a new theorem concerning the network dynamics. the theorem implies the implementation of a simple sign test which, combined with a binary tree search, efficiently performs the task of searching the equilibria. Since the proposed algorithm uses information about the network architecture and dynamic behaviour, it exhibits two important advantages over other more general methods for searching the equilibria of resistive piecewise‐linear circuits. First, the regions which cannot possibly include stable steady states can be eliminated even before starting to perform the algorithm. Secondly, there is no need to solve any set of linear equations, which is usually the most tedious part of equilibrium‐searching methods.
A novel canonic, bipolynomial analogue filter configuration with a minimum number of common‐ground capacitors
Authors: Milić Mirko , Kandić Dragan
Published: July 2007

We proposed a novel canonic, multiple‐loop feedback, bipolynomial analogue filter configuration with a minimum number of common‐ground capacitors which contains same‐type active functional blocks. A detailed analysis of sensitivity criterion minimization is given and a comparison is made with other filter configurations.
Chua's circuit 10 years later
Authors: Chua Leon O.
Published: July 2007

More than 200 papers, two special issues (Journal of Circuits, Systems, and Computers, Vol.3, Nos. 1 and 2, 1993;IEEE Transactions on Circuits and Systems, Vol. 40 No 10, 1993), an international workshop on ‘Chua's Circuit: Chaotic Phenomena and Applications’ at NOLTA ‘93, and a book (R. N. Madan (ed.),Chua's Circuit: A Paradigm for Chaos, World Scientific, Singapore, 1993) on Chua's circuit have been published since its inception a decade ago. This review paper attempts to present an overview of these timely publications, almost all within the last six months, and to identify four milestones of this very active research area.

An important milestone is the recent fabrication of amonolithicChua circuit. the robustness of this IC chip demonstrates that an array of Chua circuits can also be fabricated into a monolithic chip, thereby opening the floodgate to many unconventional applications in information technology, synergetics and even music.

The second milestone is the recent global unfolding of Chua's circuit obtained by adding a linear resistor in series with the inductor to obtain acanonicalChua circuit—now generally referred to asChua's oscillator.This circuit is most significant because it is structurally thesimplest(it contains only six circuit elements) but dynamically the most complex among all non‐linear circuits and systems described by a 21‐parameter family of continuous odd‐symmetric piecewise‐linear vector fields.

The third milestone is the recent discovery of several important new phenomena in Chua's circuits, e.g.stochastic resonance, chaos‐chaos‐type intermittency, 1/f noise spectrum, etc. These new phenomena could have far‐reaching theoretical and practical significance.

The fourth milestone is the theoretical and experimental demonstration that Chua's circuit can be easilycontrolledfrom a chaotic regime to a prescribed periodic or constant orbit, or it can besynchronizedwith two or more identical Chua circuits operating in an oscillatory or chaotic regime. These recent breakthroughs have ushered in a new era wherechaosis deliberately created and exploited for unconventional applications e.g. secure communication.
Blind signal separation using cellular neural networks
Authors: Yang Tao
Published: July 2007

In this paper a two‐layer cellular neural network (CNN) is used to separate blind signals. the topological structures of the CNN and the inner parameters are presented. the first CNN layer functions as an adaptive filter which converges asymptotically to an equilibrium point in the mean. A stochastic stability model is used to find conditions under which cells in the first layer converge. Conditions leading to correct equilibrium solutions are also presented using this model. the second CNN layer functions as a signal separator. Simulations show that the CNN blind signal separator has strong robustness and works even better than the theory predicts.
A new analytical/iterative approach to statistical delay characterization of cmos digital combinational circuits
Authors: Aftab S. A. , Styblinski M. A.
Published: July 2007

This paper is believed to be one of the first attempts to statistically characterize signal delays of basic CMOS digital building blocks. Analytic expressions in terms of the transistor geometries and technological process variations are provided for fast delay computations, to be used for manufacturing yield optimization, delay variability reduction and general VLSI circuit design for quality. the proposed approach is novel in several ways: (1) It is a combination of an accurate, semi‐empirical MOS transistor model with the use of an efficient interpolation technique to link the non‐physical model parameters to the ‘designable’ and ‘noise’ factors. (2) It uses several newly developed analytical delay formulae where possible and simple iterative solutions where direct analytical solutions do not exist. (3) the resulting hybrid analytical/iterative models are tuned, if necessary, to enhance the overall statistical accuracy. (4) Local delays are combined together for the analysis of complex combinational VLSI circuits. (5) C‐code is generated for specific delay paths to further increase efficiency (improvement in analysis times by two to four orders of magnitude with respect to SPICE, with about 5%‐10% accuracy). Examples of statistical delay characterization are used to illustrate the high accuracy of the proposed approach in modelling the influence of the ‘noise’ parameters on circuit delay relative to direct SPICE‐based Monte Carlo analysis. the important impact of the proposed approach is that statistical evaluation and optimization of delays in much larger VLSI circuits will become possible.
Design of selective lowpass sampled‐data and digital filters exhibiting equiripple amplitude and phase error characteristics
Authors: Abo‐zahhad Mohammed , Henk Tamás
Published: July 2007

A method is presented for the design of reciprocal reactant sampled‐data and digital filters exhibiting equiripple passband and stopband amplitude characteristics and approximating a linear phase characteristic such that the phase error response is equiripple too. the passband amplitude characteristic approximates unity transmission and the stopband amplitude characteristic approximates zero. Odd‐ and even‐degree cases are considered separately. the stopband amplitude response is controlled by an arbitrary number of finite transmission zeros together with two (one) zeros at infinity for even (odd) transfer functions. All the available degrees of freedom are used for controlling the filter performances. Thus the resulting solutions are selective and have good amplitude and phase characteristics. A comparison between our method and a recently published method shows that this approach has higher stopband loss and smaller phase error ripple with wider bandwidth.
Global dynamic behaviour of a three‐cell connected component detector cnn
Authors: Civalleri Pier Paolo , Gilli Marco
Published: July 2007

The global dynamic behaviour of a three‐cell connected component detector CNN described by the template [‐s, p, s] is addressed. In the casep‐1 >s> O the structure of the domains of attraction of the stable equilibria and the stable manifolds of the saddle points is represented by means of a suitable planar graph. In the cases>p‐ 1 > O it is shown that five stable and two unstable limit cycles occur. It is proved that one of the stable cycles lies entirely on the planex1= ‐x3whereas the others have the property that the second cell works only in the linear part of the output characteristic. Moreover, the domains of attraction of the stable cycles are found to be separated by the stable manifolds of the unstable equilibria (still existing fors>p‐ 1 > O ) and of the above two unstable limit cycles.
PastA—the characterization of the inherent fluctuations in the fabrication process for circuit simulation
Authors: Müller‐l Guntram E.
Published: July 2007

For worst‐case analysis, Monte Carlo analysis, yield optimization and design centring, the variations and correlations of the device model parameters in the electrical circuit simulation are of fundamental significance. This paper describes a method for the complete characterization of the inherent fluctuations in the fabrication process for the simulation in IC design. the emphasis is placed on analogue simulation owing to the complex connections between circuit design and technology and the multitude of devices with correlated parameters; nevertheless, statistical requirements for digital simulation can be fully covered.

This characterization works with all technologies whether CMOS, BiCMOS or bipolar. the prerequisites are accurate nominal device model parameters for the circuit simulation and information about fabrication statistics, e.g. process control monitor measurements. A new approach with connection coefficients for the calculation of the correlation coefficients is presented. Dependent parameters can be easily defined through a connection hierarchy. With the presented approach the variations and correlations of model parameters for simulation can be generated from estimates or measurements of the fabrication process. Based on sensitivity analysis, the variations and correlations of design objectives can be estimated. This enables the designer to do circuit analysis and optimization (limit parameters, worst‐case distances) as well as Monte Carlo analysis.
Neuropsychological study of underweight and “weight‐recovered” anorexia nervosa compared with bulimia nervosa and normal controls
Authors: Bosanac Peter , Kurlender Simone , Stojanovska Lillian , Hallam Karen , Norman Trevor , McGrath Caroline , Burrows Graham , Wesnes Keith , Manktelow Tamsin , Olver James
Published: July 2007

Objective:

To compare executive, memory and visuospatial functioning of DSM‐IV anorexia nervosa (AN), bulimia nervosa (BN), and normal controls (NC).

Method:

A comparison of women involving: (i) 16 AN with body mass indices (BMI) ≤ 17.5 kg/m2; (ii) 12 AN with BMI > 18.5 kg/m2 for at least 3 months; (iii) 13 BN; and (iv) 16 NC participants was performed with groups of similar age and intelligence. Groups were assessed with EDE‐12, MADRS, HAMA, Cognitive Drug Research (CDR) battery, and Bechara tasks.

Results:

Significant impairments in CDR Power of Attention were present in underweight AN and BN participants. CDR Morse Tapping was significantly impaired in all clinical groups. The BN and weight‐recovered AN groups were significantly impaired on CDR immediate word recall. The BN group alone was significantly impaired on CDR delayed word recall.

Conclusion:

Attentional impairment is similar in AN and BN. Impaired motor tasks in AN persist after “weight‐recovery” and are similar to impairments in BN. BN may be discriminated from AN on word recall. © 2007 by Wiley Periodicals, Inc. Int J Eat Disord 2007
Anorexia nervosa and Raynaud's phenomenon: A case report
Authors: Yucel Basak , Uzum Ayse Kubat , Ozbey Nese , Kamali Sevil , Yager Joel
Published: July 2007

Objective:

To describe and discuss potential relationships between anorexia nervosa (AN) and Raynaud's phenomenon, the course and concurrent treatment of these two disorders as they appeared simultaneously, and a potential treatment modification entailed in such concurrent therapies.

Background:

Although Raynaud's phenomenon has been described during the course of AN, the associations and interactions between these two conditions are not clear.

Method:

We report the medical workup, treatment, and outcomes in a 19‐year old female patient who developed Raynaud's phenomenon following the onset of AN.

Results:

After treatment with nutritional rehabilitation, counseling, and individual and group therapy, the patient's weight, eating disorder‐related behaviors, and attitudes improved significantly. Raynaud's related symptoms improved, following treatment with a calcium channel blocker and antiaggregant therapy. In conjunction with nutritional efforts to treat the patient's long‐standing amenorrhea and osteopenia, the treatment team elected to also administer estrogen hormone in addition to oral calcium and vitamin D supplementation. Since oral contraceptives are to be avoided in patients with Raynaud's phenomenon who show clinical findings suggesting connective tissue disorder, the treatment team elected to treat this patient with transdermal hormone replacement therapy.

Conclusion:

The co‐occurrence of AN and Raynaud's phenomenon merits close and persistent follow‐up by a multidisciplinary team and may lead to alterations of usual therapeutic approaches. © 2007 by Wiley Periodicals, Inc.
Treatment perception in adolescent onset anorexia nervosa: Retrospective views of patients and parents
Authors: Halvorsen Inger , Heyerdahl Sonja
Published: July 2007

Objective:

To investigate perception of treatment in former patients with anorexia nervosa (AN) and their parents, and to determine whether this was related to outcome and treatment characteristics. Client satisfaction is important for treatment engagement and adherence.

Method:

Forty‐six (of 55) girls with adolescent onset AN, 33 mothers and 26 fathers participated in a follow‐up study conducted 8.8 (SD 3.3) years after start of treatment. The former patients were assessed using diagnostic interviews. Only nine participants (19%) had an eating disorder (ED) at follow‐up. Perception of treatment was assessed by questionnaires.

Results:

Parents reported having an overall positive perception of treatment. However, reports from former patients were significantly more negative than from the parents. In former patients, the “perception of therapists” total score and the items “therapists' knowledge of ED” and “usefulness of pediatric inpatient treatment” correlated with ED symptoms at follow‐up. The perception of therapists scores of the parents were not associated with the ED outcome of their daughters. More family therapy sessions were associated with the former patients' satisfaction with the therapists, while higher age at admission was associated with their mothers' satisfaction.

Conclusion:

In spite of good ED outcome, former patients were only moderately satisfied with their treatment, whereas parental satisfaction was high. © 2007 by Wiley Periodicals, Inc.
Exposure of glia to pro‐oxidant agents revealed selective Stat1 activation by H2O2 and Jak2‐independent antioxidant features of the Jak2 inhibitor AG490
Authors: Gorina Roser , Sanfeliu Coral , Galitó Aida , Messeguer Àngel , Planas Anna M.
Published: July 2007

The JAK/STAT pathway is activated in response to cytokines and growth factors. In addition, oxidative stress can activate this pathway, but the causative pro‐oxidant forms are not well identified. We exposed cultures of rat glia to H2O2, FeSO4, nitroprussiate, or paraquat. We assessed oxidative stress by measuring reactive oxygen species (ROS) and oxidated proteins, we determined phosphorylated Stat1 (pStat1), and we evaluated the effect of antioxidants (trolox, propyl gallate, and N‐acetylcysteine) and of Jak2 (Janus tyrosine kinases) inhibitors (AG490 and Jak2‐Inhibitor‐II). Pro‐oxidant agents induced ROS and protein oxidation, excluding nitroprussiate that induced protein nitrosylation. H2O2, and to a lesser extent FeSO4, increased the level of pStat1, whereas nitroprussiate and paraquat did not. Trolox and propyl gallate strongly prevented ROS formation but they did not abolish H2O2‐induced pStat1. In contrast, NAC did not reduce the level of ROS but it prevented the increase of pStat1 induced by H2O2, evidencing a differential effect on ROS formation and on Stat1 phosphorylation. H2O2 induced pStat1 in mixed glia cultures and, to a lesser extent, in purified astroglia, but not in microglia. Jak2 inhibitors reduced H2O2‐induced pStat1, suggesting the involvement of this kinase in the increased phosphorylation of Stat1 by peroxide. Unexpectedly, AG490, but not Jak2‐Inhibitor‐II, reduced ROS formation, and it abrogated lipid peroxidation in microsomal preparations. Furthermore, AG490 reduced ROS in glial cells that were transfected with siRNA to silence Jak2 expression. These findings reveal previously unrecognized Jak2‐independent antioxidant properties of AG490, and show that Jak2‐dependent Stat1 activation by peroxide is dissociated from ROS generation. © 2007 Wiley‐Liss, Inc.
Cognitive impairment in older people: future demand for long‐term care services and the associated costs
Authors: Comas‐Herrera Adelina , Wittenberg Raphael , Pickard Linda , Knapp Martin
Published: July 2007

Background

Projections are presented of future numbers of older people with cognitive impairment (CI) in England, their demand for long‐term care (LTC) services and future costs of their care. The sensitivity of the projections to factors that are likely to affect future LTC expenditure is explored. These factors include future numbers of older people, prevalence rates of CI, trends in household composition, informal care provision, care service patterns and unit costs.

Methods

A macrosimulation (or cell‐based) model was developed to produce the projections, building on an earlier PSSRU model. Base case assumptions are made about trends in key factors expected to impact on future LTC expenditure, and variant assumptions about the key factors are introduced to test for sensitivity.

Results

Expenditure on LTC services for older people with CI is projected to rise from 0.60% of Gross Domestic Product (GDP) (£5.4 billion) in 2002 to 0.96% of GDP (£16.7 billion) in 2031, under base case assumptions. Under variant assumptions, the projection for 2031 ranges from 0.83% to 1.11% of GDP. These figures do not include the opportunity costs of informal care.

Conclusions

Sensitivity analysis shows that projected demand for LTC is sensitive to assumptions about the future numbers of older people and future prevalence rates of CI and functional disability. Projected expenditure is also sensitive to assumptions about future rises in the real unit costs of services. Copyright © 2007 John Wiley & Sons, Ltd.
Functional neuroanatomy of the parahippocampal region: The lateral and medial entorhinal areas
Authors: Kerr Kristin M. , Agster Kara L. , Furtak Sharon C. , Burwell Rebecca D.
Published: July 2007

The entorhinal cortex (EC) serves a pivotal role in corticohippocampal interactions, but a complete description of its extrinsic connections has not been presented. Here, we have summarized the cortical, subcortical, and hippocampal connections of the lateral entorhinal area (LEA) and the medial entorhinal area (MEA) in the rat. We found that the targets and relative strengths of the entorhinal connections are strikingly different for the LEA and MEA. For example, the LEA receives considerably heavier input from the piriform and insular cortices, whereas the MEA is more heavily targeted by the visual, posterior parietal, and retrosplenial cortices. Regarding subcortical connections, the LEA receives heavy input from the amygdala and olfactory structures, whereas the MEA is targeted by the dorsal thalamus, primarily the midline nuclei and also the dorsolateral and dorsoanterior thalamic nuclei. Differences in the LEA and MEA connections with hippocampal and parahippocampal structures are also described. In addition, because the EC is characterized by bands of intrinsic connectivity that span the LEA and MEA and project to different septotemporal levels of the dentate gyrus, special attention was paid to the efferents and afferents of those bands. Finally, we summarized the connections of the dorsocaudal MEA, the region in which the entorhinal “grid cells” were discovered. The subregional differences in entorhinal connectivity described here provide further evidence for functional diversity within the EC. It is hoped that these findings will inform future studies of the role of the EC in learning and memory. © 2007 Wiley‐Liss, Inc.
CA3 NMDA receptors are required for experience‐dependent shifts in hippocampal activity
Authors: Kent Kelly , Hess Kenneth , Tonegawa Susumu , Small Scott A.
Published: July 2007

The anatomical distribution of sensory‐evoked activity recorded from the hippocampal long‐axis can shift depending on prior experience. In accordance with Marr's computational model of hippocampal function, CA3 NMDA receptors have been hypothesized to mediate this experience‐dependent shift in hippocampal activity. Here we tested this hypothesis by investigating genetically‐modified mice in which CA3 NMDA receptors are selectively knocked‐out (CA3‐NR1 KO). First, we were required to develop an fMRI protocol that can record sensory‐evoked activity from the mouse hippocampal long‐axis. This goal was achieved in part by using a dedicated mouse scanner to image odor‐evoked activity, and by using non‐EPI (echo planer imaging) pulse sequences. As in humans, odors were found to evoke a ventral‐predominant activation pattern in the mouse hippocampus. More importantly, odor‐evoked activity shifted in an experience‐dependent manner. Finally, we found that the experience‐dependent shift in hippocampal long‐axis activity is blocked in CA3‐NR1 knock‐out mice. These findings establish a cellular mechanism for the plasticity imaged in the hippocampal long‐axis, suggesting how experience‐dependent modifications of hippocampal activity can contribute to its mnemonic function. © 2007 Wiley‐Liss, Inc.
Moss beneath a leafless larch canopy: influence on water and energy balances in the southern mountainous taiga of eastern Siberia
Authors: Suzuki Kazuyoshi , Kubota Jumpei , Yabuki Hironori , Ohata Tetsuo , Vuglinsky Valery
Published: July 2007

The southern mountainous taiga of eastern Siberia has a sparse larch canopy and an understory dominated by a thick moss layer. The physiology of moss is very different from that of other plants, as mosses lack roots and vascular systems and take up water directly. During May 2002, we conducted hydrological and meteorological measurements in the taiga of eastern Siberia to investigate the role of understory moss on water and energy balances within a leafless larch forest. We found that below‐leafless canopy net all‐wave radiation partitions into 39% latent heat flux and 39% sensible heat flux, while the mean daily Bowen ratio is about 1. Ground heat flux on the moss surface is also an important factor, as it comprises 22% of net all‐wave radiation. Evaporation from moss beneath the leafless canopy was 24 mm during the 1‐month observation period, representing 23% of the water flux into the larch forest. This finding implies that moss intercepted 23% of the water flux into the larch forest. In addition, evaporation from the moss understory during May 2002 comprised 22% of total evapotranspiration previously estimated above the canopy (April–October 2001). We conclude that moss is an important component of the water and energy balance in larch forests in the taiga region. Copyright © 2007 John Wiley & Sons, Ltd.