bluuebunny/crossref_metadata_2025 huggingface dataset:
EFFICIENT DECIMATOR AND INTERPOLATOR ARRAY STRUCTURES
Authors: ABDEL-RAHEEM ESAM , EL-GUIBALY FAYEZ , ANTONIOU ANDREAS
Published: November 2004

New and efficient array processor implementations of polyphase FIR and IIR decimators and interpolators, with integer compression and expansion factors, are derived using an algebraic mapping technique. The technique is based on the time-domain representation of the algorithms. It has the merit of being suitable for describing multirate algorithms. The control signals necessary to implement the polyphase structures are explicitly identified. Different array structures are derived in which the inputs are broadcast or pipelined and outputs are pipelined or added simultaneously. Upper bounds on the input/output processing rates are provided in terms of system parameters and hardware delays. The work is extended to map decimators/interpolators with fractional compression/expansion factors onto systolic hardware structures. The new structures have the advantages of being modular, regular, hierarchical, and pipelined.
EXPERIMENTAL STATIC AND DYNAMIC CHARACTERISTICS OF MOS-CONTROLLED THYRISTORS FOR RESISTIVE LOADS
Authors: KAZIMIERCZUK MARIAN K. , THIRUNARAYAN NANDAKUMAR , NGUYEN BICK T. , WEIMER JOSEPH A.
Published: November 2004

Experimental results are given for a PMOS-controlled thyristor (PMCT). The static IA-VAK characteristics of a PMCT were measured using a programmable high power curve tracer for both forward and reverse anode-to-cathode voltage VAK at different temperatures. The characteristics are similar to the ID-VD characteristics of typical p-n junction diodes. The device has a low forward voltage drop at high-current levels, e.g. VF(AK) = 1.6 V at IA = 200 A . The dynamic behavior of the PMCT was measured in a single switch configuration under resistive loading. The transient waveforms of anode current iA, gate current iG, anode-to-cathode voltage vAK, and gate-to-anode drive voltage vGA were observed at turn-on and turn-off for power levels up to 5 kW. The measured turn-on time was 0.3 μs and the measured turn-off time was 2.2 μs. The switching power loss and the conduction power loss were 3 W and 18 W, respectively.
CMOS PWM CONTROL CIRCUIT WITH PROGRAMMABLE DEAD TIME
Authors: SIFERD RAYMOND E. , CRAVENS ROBERT C. , KAZIMIERCZUK MARIAN K.
Published: November 2004

Some types of dc–dc power converters require a control circuit to produce two pulse width modulated (PWM) signals that are 180° out of phase. In many applications, a critical element of the control circuit is the capability to program a specified amount of dead time when both PWM signals are low. This paper presents an integrated circuit implementation of a control circuit that can be programmed with digital inputs to produce variable dead times. The circuit was fabricated in 2-micron CMOS technology with a 1.7 mm × 1.7 mm die and tested to verify complete functionality. Control chips that are currently available require external capacitor/resistor combinations to produce the required dead time. A unique design of a Bi-CMOS buffer with an output current up to 1.4 A is also included, which enables the PWM circuit to directly drive the gates of power MOSFETs.
SNUBBER BEHAVIOR AND DESIGN IN FLYBACK CONVERTERS FOR ISOLATED IGBT DRIVERS
Authors: BRAMBILLA ANGELO
Published: November 2004

When flyback converters are connected to floating loads, voltage swings at the output can give rise to spikes which pass through the flyback transformer stray capacitor. This happens when flyback converters supply IGBT floating gate drivers. These voltage spikes can interfere with the correct behavior of the gate driver. In order to reduce the transformer stray capacitance, the two windings must be wound on the opposite sides of the core. However, this reduces the coupling factor of the transformer by increasing its leakage inductance and snubbers must be employed in some cases.

This paper deals with snubber design and behavior for flyback converter applications. Since it is shown that snubbers transfer the energy through the flyback transformer, they should be designed in a different way with respect to conventional applications.
INTRODUCING PULSE ANGLE MODULATION FOR INVERTERS
Authors: EL-BAKRY MAHMOUD
Published: November 2004

This paper introduces three types of pulse angle modulations found to be suitable for application to variable voltage variable frequency inverters, namely: (i) pulse position modulation, (ii) pulse frequency modulation and (iii) pulse repetition period modulation. Their harmonic analyses show very low relative values of low order harmonics, near the reference frequency. Modifications to the second and third types are introduced to further reduce the relative values of low order harmonics. Variation of the magnitude of the reference frequency component is investigated by varying either the modulation factor or the duty cycle. It was proven and verified that varying the duty cycle does not affect the harmonic spectrum near the reference frequency.
FORMAL METHODS TO AID THE EVOLUTION OF SOFTWARE
Authors: WARD M. P. , BENNETT K. H.
Published: November 2004

There is a vast collection of operational software systems which are vitally important to their users, yet are becoming increasingly difficult to maintain, enhance, and keep up to date with rapidly changing requirements. For many of these so-called legacy systems, the option of throwing the system away and rewriting it from scratch is not economically viable. Methods are therefore urgently required which enable these systems to evolve in a controlled manner. The approach described in this paper uses formal proven program transformations, which preserve or refine the semantics of a program while changing its form. These transformations are applied to restructure and simplify the legacy systems and to extract higher-level representations. By using an appropriate sequence of transformations, the extracted representation is guaranteed to be equivalent to the code. The method is based on a formal wide spectrum language, called WSL, with an accompanying formal method. Over the last ten years we have developed a large catalog of proven transformations, together with mechanically verifiable applicability conditions. These have been applied to many software development, reverse engineering, and maintenance problems. In this paper, we focus on the results of using this approach in the reverse engineering of medium scale, industrial software, written mostly in languages such as assembler and JOVIAL. Results from both benchmark algorithms and heavily modified, geriatric software are summarized. We conclude that formal methods have an important practical role in software evolution.
AN EVOLUTION-BASED APPROACH TO PROGRAM UNDERSTANDING USING CULTURAL ALGORITHMS
Authors: REYNOLDS ROBERT G. , SVERDLIK WILLIAM
Published: November 2004

Program understanding plays a very important role in the software engineering field as an essential part of the widely accepted reuse process. Unfortunately, the lack of general tools for this purpose often prevents users from effectively retrieving software modules for reuse. The primary difficulty is in determining which of the already-available modules performs the desired function. This paper explores the task of extracting functional knowledge from a program object (i.e., coded module) using an evolutionary-learning technique, cultural algorithms, to automatically learn classification rules for a reuse library. The modules are stored in a reuse library in the PM system using a faceted classification scheme. Therefore, the goal is to learn a set of rules to characterize the semantics of code modules based on their syntactic structure. The most difficult part of the process is to identify those parts of the program that provide specific evidence of the presence of a concept. Here, evolutionary-learning techniques are employed to interactively identify lines in a module that are "believed" to provide evidence for the presence of a facet value (concept) in the code by a user. A prototype is used to learn concepts relating to the "list" and "stack" programming concepts.
A FUNCTIONAL REPRESENTATION FOR SOFTWARE REUSE AND DESIGN
Authors: LIVER BEAT , ALLEMANG DEAN T.
Published: November 2004

In this paper, we present a framework for maintainable software design, based on a multilevel understanding of software function. This framework is the novel functional representation ZD, in which domain concepts (e.g., employee records) as well as computational concepts (e.g., stacks and queues) are represented in a reusable manner. We use ZD to support the construction of a library of reusable components for novel configurations. In order to achieve this, we provide mechanisms for supporting flexible configurations, address problems of determining the correctness of a combination of library components, and consider the computational complexity of finding combinations. These problems all stem from problems of interactions between components. Therefore, the structure of ZD is focused on representing and handling these interactions. We show how the approach based on ZD resolves certain well-known problems faced by other library-based component reuse architectures.
REACHABILITY TESTING: AN APPROACH TO TESTING CONCURRENT SOFTWARE
Authors: HWANG GWAN-HWAN , TAI KUO-CHUNG , HUANG TING-LU
Published: November 2004

Concurrent programs are more difficult to test than sequential programs because of non-deterministic behavior. An execution of a concurrent program non-deterministically exercises a sequence of synchronization events called a synchronization sequence (or SYN-sequence). Non-deterministic testing of a concurrent program P is to execute P with a given input many times in order to exercise distinct SYN-sequences. In this paper, we present a new testing approach called reachability testing. If every execution of P with input X terminates, reachability testing of P with input X derives and executes all possible SYN-sequences of P with input X. We show how to perform reachability testing of concurrent programs using read and write operations. Also, we present results of empirical studies comparing reachability and non-deterministic testing. Our results indicate that reachability testing has advantages over non-deterministic testing.
BOOTSTRAP: A SOFTWARE PROCESS ASSESSMENT AND IMPROVEMENT METHODOLOGY
Authors: SIMILÄ JOUNI , KUVAJA PASI , KRZANIK LECH
Published: November 2004

The BOOTSTRAP approach to software process assessment and improvement offers a methodology which can be suitably used with different types of the software process and products, and with different software producing organization structures and sizes. The approach is supported by cumulative data about the software industry as a whole as well as its individual sectors. At the same time BOOTSTRAP is based on the ISO 9000 series quality standards and appropriately general software project management standards (ESA-PSS-05), as well as is related to such defacto maturity standards as SEI's CMM. More granularity in expressing capability (in terms of scale and multidimensionality) makes BOOTSTRAP particularly suitable for process improvement. While having established position in Europe and participating in such wider standardization efforts as ISO/SPICE, it is important for BOOTSTRAP to look for comparisons of assumptions and results elsewhere. This paper presents the BOOTSTRAP methodology and and in conclusions brings forward some topics that may constitute a cultural interface orspecific boundary conditions between different software process assessment and improvement approaches.
COGITO: A METHODOLOGY AND SYSTEM FOR FORMAL SOFTWARE DEVELOPMENT
Authors: BLOESCH A. , KAZMIERCZAK E. , KEARNEY P. , TRAYNOR OWEN
Published: November 2004

Cogito 1 is the first iteration of a Z-based integrated methodology and support system for formal software development. This paper gives an overview of the Cogito methodology and associated tools. Particular emphasis is placed on the way in which Cogito integrates the various phases of the formal development process and provides comprehensive tools support for all phases of development addressed by the methodology.
A KNOWLEDGE-BASED SYSTEM TO MODEL HUMAN SUPERVISORY CONTROL IN DYNAMIC PLANNING
Authors: DAVE RAKESH , GANAPATHY SUBHASHINI , FENDLEY MARY , NARAYANAN S.
Published: November 2004

With the increases in the levels of automation and computerization, supervisory control systems are becoming increasingly common in commercial and military applications. A supervisory control system consists of one or more human operators interacting with highly automated components such as those seen in satellite ground control, flexible manufacturing systems, or nuclear power plants. Humans typically perform cognitively intense tasks such as monitoring, planning, real-time control, and troubleshooting, and are ultimately responsible for the safe and efficient operation of the overall system. Although developments on supervisory control have led to useful applications in interface design and automation, there is a scarcity of research that empirically evaluates human decision making in supervisory control through emulation of task performance using knowledge-based systems. In the context of dynamic planning involving simulated search and rescue missions using ground based autonomous robots and uninhabited aerial vehicles, we developed a knowledge-based system that mimics supervisory control performance. This paper describes the application domain, the details of the simulation model, and the implementation and assessment of a knowledge-based system that mimics human supervisory control performance.
EFFECTS OF FORMAL PLANNING AND CONTROL ON GROWTH: A CASE STUDY APPROACH
Authors: ROMANO CLAUDIO A. , RATNATUNGA JANEK
Published: November 2004

While planning and control and their impact on small firm growth are implicit in many academic discussions, much of our understanding of these phenomena are based on speculation and opinion. Thus, they seem neglected areas of small business research. This paper seeks to improve the understanding of formal planning and control systems and their relationship to the growth of small business in Australian manufacturing.

First, a framework is developed which incorporates the main contextual variables which independently and simultaneously have been shown to have a major relationship with growth. Second, the study provides empirically-based qualitative evidence to further the understanding of causality in the growth of small business by focusing on how formal planning and control systems are embedded within the external or internal contextual variables of small business and the characteristics of their management.

Evidence is also provided as to the conditions and circumstances under which formal planning and control are likely to be most effective in controlling the effects of contextual variables, and to the differences between high growth and low growth firms in the use of formal planning and control. The findings of this study are important for two principal reasons. First, it has provided the opportunity to conduct exploratory research into how a small business is managed within the context in which the processes are applied. Second, it has provided the opportunity to identify factors which encourage or discourage small firms to plan, thus providing a better understanding of the planning and control process adopted by small firms.
THE DEVELOPMENT OF CHINA'S PRIVATE ENTREPRENEURSHIP
Authors: CHAU SANDY S.
Published: November 2004

This paper serves as a review on the recent growth of private entrepreneurship in China. Since the economic reform began, private enterprise has become one of the fastest growing segments of China's economy. Prior to December 1978, when private sector activities were legalized, China had a mere 150,000 registered self-employed workers. In 1981, the State Council specified the size and scope of private sector activities in which urban 'geti hu', or individual households, were allowed to operate. In 1987, Beijing allowed for a second classification of private entrepreneur, the 'siying giye', or private enterprise with more than eight employees. Based on two major national surveys in 1992 and 1993 on private enterprises, this paper reports on this new breed of Chinese private entrepreneurship.
POWER PROPERTIES OF THE T2 CONTROL CHART
Authors: WIERDA SIEBRAND J. , STEERNEMAN TON
Published: November 2004

The T2 control chart is a multivariate SPC tool that monitors the mean vector of a process and that examines whether it remains stable over time. This paper examines the probability that the T2 control chart signals for an out-of-control situation. This probability is called the power of the chart. We study the effect on the power consequent on a change in the sample sizes, the dimension, or the level. For the bivariate case, we consider the impact on the power consequent on a change in the correlation coefficient. Finally, we examine what happens if the assumption that the covariance matrix is stable over time is violated.
STATISTICAL PROCESS CONTROL FOR LOW NONCONFORMITY PROCESSES
Authors: GOH T.N. , XIE M.
Published: November 2004

Statistical process control of high quality products is an important issue in modern quality control applications because of the success of continuous improvement efforts worldwide. The conventional Shewhart control charts based on 3-sigma control limits tend to encounter certain practical and theoretical problems as “zero-defect” is approached. In this paper, we describe some general approaches to solving this problem, focusing on the control charts for nonconformities or defects. We suggest that for a moderate nonconformity process, the exact probability limits should be used. For a lower non-conformity process, a “pattern recognition” approach can be applied. Finally, for a near-zero nonconformity process, a modified approach based on the cumulative count of nonconformities can be used.
DYNAMIC RELIABILITY MEASURES AND LIFE DISTRIBUTION MODELS FOR MULTISTATE SYSTEMS
Authors: YANG KAI , XUE JIANAN
Published: November 2004

This paper generalizes the dynamic binary state reliability parameters R(t), F(t), λ(t) and MTBF to corresponding dynamic multistate reliability parameter vectors R(t), F(t), λ(t) and M. Then, probability models for system lifetime used on binary state reliability models, such as exponential, Weibull, and other distributions are generalized for multistate models. Continuous time Markov process and Semi-Markov process are used to model the lifetime distribution for multistate system. Multistate reliability measures, such as R(t), F(t), λ(t), M are derived for those multistate reliability models.
SOFTWARE FAILURE DATA ANALYSIS USING THE LEAST SQUARES APPROACH AND THE TIME PER FAILURE CONCEPT
Authors: KNAFL G.J. , MORGAN J.A. , FOLLENWEIDER R.L. , KARCICH R.M.
Published: November 2004

We adapt data analytic techniques to the software reliability setting. We develop an evaluation procedure based on scatterplots of transformed data, crossvalidation using the predicted residual sum of squares (PRESS) criterion, residual plots, and normal plots. We analyze a software failure data set collected at Storage Technology Corporation utilizing this evaluation technique. We identify a new model which, for this data set, outperforms several established software reliability models, including the delayed S-shaped, exponential, inverse linear, logarithmic, power, and log power models. The failure intensity, and hence the reliability, for this model at any point in time is a function of the time per failure, that is, the ratio of cumulative time divided by cumulative failures, a quantity that agrees with the mean time between failures for time points at which failures occur.
ON IMPORTANCE MEASURES USED IN COMMON CAUSE FAILURE QUANTIFICATION
Authors: PAN ZHIJIE , NONAKA YASUO
Published: November 2004

In quantitative analysis of common cause failures (CCFs), importance measures for ranking the importance of the CCF events will be significant to limit the CCF analysis framework, find out efficient defence strategies against CCF, and make sensitivity analysis for them. In this paper, three importance measures are defined for different types of common cause failure events: Structure Importance, Probability Importance, and β-Importance. Simplified algorithms for calculating these importance measures are developed.
PERSPECTIVE AND OVERVIEW OF MANUFACTURING INITIATIVES IN THE UNITED STATES
Authors: LEE JAY
Published: November 2004

The strategic application of the computer-integrated manufacturing technology can markedly improve manufacturers’ product quality, responsiveness to customers, process control and flexibility, and flexibility of capital investment — all determinants of global manufacturing competitiveness. Companies need to reach customers or suppliers anywhere in the world to develop the network of global alliances and partnerships among businesses. This paper discusses the enabling technologies that support manufacturing globalization. It also introduces the major initiatives in Computer-Integrated Manufacturing (CIM) in the United States. Finally, new challenges in moving the computer-integrated manufacturing to a global marketplace is addressed.
ON MODELING AND ANALYZING CORRUPTED RELIABILITY DATA
Authors: WATKINS A.J. , GRIFFIN R.M.
Published: November 2004

This paper is concerned with the effect of various data recording errors on the estimation of parameters in models commonly used in the analysis of reliability data. We start by outlining sources of such errors, and propose some modeling strategies that allow these errors into the framework of our analysis. It is then shown that the estimation of model parameters needs to take into account a mis-specified model, with the consequence that any theoretical advantages nominally enjoyed by estimators are reduced. In particular, the results from a series of simulation experiments show that the maximum likelihood estimator is no longer asymptotically unbiased. We next outline an approach that generalizes the usual asymptotic theory to obtain expressions for both the mean and variance of the maximum likelihood estimator in the present framework; these expressions involve both the underlying distribution and parameters controlling the extent to which recording errors are present in a data set. We then link these expressions to results obtained in a series of simulation experiments, and show that this approach accommodates a general formulation of the effect of data recording errors. We conclude with a discussion of the practical consequences of this work.
BROADCASTING IN A THREE-STAGE POINT-TO-POINT NONBLOCKING NETWORK
Authors: HWANG F.K. , LIN C.H.
Published: November 2004

Three-stage networks have been widely studied as a point-to-point network and later, also as a broadcast network. In this paper we consider using such networks for point-to-point calls and broadcasting calls simultaneously. We note that the point-to-point nonblocking property and the broadcast rearrangeable property do not coexist due to different routing strategies. We propose a new routing strategy for broadcast calls which preserves the point-to-point nonblocking property, and keeps the broadcast calls almost rearrangeable when most calls are point-to-point.
STUDY OF TRAPPING RATE AND DEFECT DENSITY IN AlSi11.35Mg0.23 BY POSITRON ANNIHILATION TECHNIQUE
Authors: ABDEL-RAHMAN M. A. , ABDALLAH M. S. , BADAWI EMAD A.
Published: November 2004

The measurements of Positron Annihilation Lifetime Technique (PALT) have been performed on AlSi 11.35 Mg 0.23 Alloys. It has been shown that positrons can become trapped at imperfect locations in solids and their mean lifetime can be influenced by changes in the concentration of such defects. No change has been observed in the mean lifetime values at the saturation of defect concentration. The trapping rates of positrons can be determined for thickness reduction up to 11% for dislocation. The concentration of defect (ρ') range varies from 8.65×1015 to 2.35×1018 cm -3 up to the maximum value of strain (ε) 0.23.
RESONANT PHOTOEMISSION OF N2O ON Ir(110)
Authors: CARABINEIRO S. A. C. , DE GROOT F. M. F , KJELDGAARD L. , RUBENSSON J.-E. , NIEUWENHUYS B. E.
Published: November 2004

The adsorption of N 2 O on Ir (110) was investigated with high-resolution resonant photoemission at 135 K. The results obtained show evidence of molecular adsorption of N 2 O , along with some dissociation. It is found that the nitrogen photoemission spectra measured at the terminal and central nitrogen energy positions of the N 2 O / Ir (110) system are equivalent to those of N 2 O in the gas phase. In contrast, the oxygen spectrum shows little resemblance to the gas phase oxygen spectrum of N 2 O . In the nitrogen resonant photoemission spectra one can only discover resonant behavior with constant binding energy peaks. In contrast, the oxygen resonant photoemission spectra shows dominantly Auger behavior with peaks at constant kinetic energies. Both observations reveal that the oxygen is bonded to the Ir surface. A systematic study as a function of coverage and temperature and a comparison with other surfaces differing in structure and composition is needed to understand the variations in the adsorption behavior of N 2 O on metal surfaces.
ATOMIC FORCE MICROSCOPY STUDIES ON GROWTH STEPS AND 2D NUCLEI ON THE {100} FACES OF DEUTERATED L-ARGININE PHOSPHATE CRYSTALS
Authors: GENG Y. L. , XU D. , SUN D. L. , DU W. , LIU H. Y. , ZHANG G. H. , WANG X. Q.
Published: November 2004

Growth steps and 2D nuclei of the {100} faces of the deuterated L-arginine phosphate (DLAP) crystals have been studied using ex-situ atomic force microscopy (AFM). Straight steps along the b direction as well as meandered steps are detected. The bunched steps have wider terraces than the elementary ones, which are supposed to result from the slower growth rate of the former than the latter. Many 2D nuclei exist on the step terraces and edges acting as the growth sources. Occasionally, 2D islands generated by 2D nuclei could also be observed. In conclusion, the crystal grows by layer growth mechanism.
CONTRIBUTION OF THE MORPHOLOGICAL GRAIN SIZES TO THE ELECTRICAL RESISTIVITY OF PLATINUM AND GOLD THIN FILMS
Authors: CATTANI M. , SALVADORI M. C.
Published: November 2004

We have measured the morphological grain sizes of nanostructured platinum and gold thin films. In previous works their electrical resistivities have been measured and a theoretical approach was proposed to explain the resistivity experimental data. It will be shown that within the framework of our theoretical approach, the morphological grain sizes play an essential role in the electrical resistivity of these metallic thin films.
Muscarinic activation of Na+-dependent ion transporters and modulation by bicarbonate in rat submandibular gland acinus
Authors: Lee Ji Eun , Nam Joo Hyun , Kim Sung Joon
Published: November 2004

To investigate the interaction between the ion channels and transporters in the salivary fluid secretion, we measured the membrane voltage ( Vm) and intracellular concentrations of Ca2+, Na+([Na+]c), Cl−, and H+(pHi) in rat submandibular gland acini (RSMGA). After a transient depolarization induced by a short application of acetylcholine (ACh; 5 μM, 20 s), RSMGA showed strong delayed hyperpolarization ( Vh,ACh; −95 ± 1.8 mV) that was abolished by ouabain. In the HCO3−-free condition, the Vh,AChwas also blocked by bumetanide, a blocker of Na+-K+-2Cl−cotransporter (NKCC). In the presence of HCO3−(24 meq, bubbled with 5% CO2), however, the Vh,AChwas not blocked by bumetanide, but it was suppressed by ethylisopropylamiloride (EIPA), a Na+/H+exchanger (NHE) inhibitor. Similarly, the ACh-induced increase in [Na+]cwas totally blocked by bumetanide in the absence of HCO3−, but only by one-half in the presence of HCO3−. ACh induced a prominent acidification of pHiin the presence of HCO3−, and the acidification was further increased by EIPA treatment. Without HCO3−, an application of ACh strongly accelerated the NKCC activity that was measured from the decay of pHiduring the application of NH4+(20 mM). Notably, the ACh-induced activation of NKCC was largely suppressed in the presence of HCO3−. In summary, the ACh-induced anion secretion in RSMGA is followed by the activation of NKCC and NHE, resulting an increase in [Na+]c. The intracellular Na+-induced activation of electrogenic Na+/K+-ATPase causes Vh,ACh. The regulation of NKCC and NHE by ACh is strongly affected by the physiological level of HCO3−.
Mathematical model of oxygen distribution in engineered cardiac tissue with parallel channel array perfused with culture medium containing oxygen carriers
Authors: Radisic Milica , Deen William , Langer Robert , Vunjak-Novakovic Gordana
Published: November 2004

A steady-state model of oxygen distribution in a cardiac tissue construct with a parallel channel array was developed and solved for a set of parameters using the finite element method and commercial software (FEMLAB). The effects of an oxygen carrier [Oxygent; 32% volume perfluorocarbon (PFC) emulsion] were evaluated. The parallel channel array mimics the in vivo capillary tissue bed, and the PFC emulsion has a similar role as the natural oxygen carrier hemoglobin in increasing total oxygen content. The construct was divided into an array of cylindrical domains with a channel in the center and tissue space surrounding the channel. In the channel, the main modes of mass transfer were axial convection and radial diffusion. In the tissue region, mass transfer was by axial and radial diffusion, and the consumption of oxygen was by Michaelis-Menten kinetics. Neumann boundary conditions were imposed at the channel centerline and the half distance between the domains. Supplementation of culture medium by PFC emulsion improved mass transport by increasing convective term and effective diffusivity of culture medium. The model was first implemented for the following set of experimentally obtained parameters: construct thickness of 0.2 cm, channel diameter of 330 μm, channel center-to-center spacingof 700 μm, and average linear velocity per channel of 0.049 cm/s, in conjunction with PFC supplemented and unsupplemented culture medium. Subsequently, the model was used to define favorable scaffold geometry and flow conditions necessary to cultivate cardiac constructs of high cell density (108 cells/ml) and clinically relevant thickness (0.5 cm). In future work, the model can be utilized as a tool for optimization of scaffold geometry and flow conditions.
Sympathetic outflow enhances the stretch reflex response in the relaxed soleus muscle in humans
Authors: Hjortskov Nis , Skotte Jørgen , Hye-Knudsen Christian , Fallentin Nils
Published: November 2004

Animal experiments suggest that an increase in sympathetic outflow can depress muscle spindle sensitivity and thus modulate the stretch reflex response. The results are, however, controversial, and human studies have failed to demonstrate a direct influence of the sympathetic nervous system on the sensitivity of muscle spindles. We studied the effect of increased sympathetic outflow on the short-latency stretch reflex in the soleus muscle evoked by tapping the Achilles tendon. Nine subjects performed three maneuvers causing a sustained activation of sympathetic outflow to the leg: 3 min of static handgrip exercise at 30% of maximal voluntary contraction, followed by 3 min of posthandgrip ischemia, and finally during a 3-min mental arithmetic task. Electromyography was measured from the soleus muscle with bipolar surface electrodes during the Achilles tendon tapping, and beat-to-beat changes in heart rate and mean arterial blood pressure were monitored continuously. Mean arterial pressure was significantly elevated during all three maneuvers, whereas heart rate was significantly elevated during static handgrip exercise and mental arithmetic but not during posthandgrip ischemia. The peak-to-peak amplitude of the short-latency stretch reflex was significantly increased during mental arithmetic ( P < 0.05), static handgrip exercise ( P < 0.001), and posthandgrip ischemia ( P < 0.005). When expressed in percent change from rest, the mean peak-to-peak amplitude increased by 111 (SD 100)% during mental arithmetic, by 160 (SD 103)% during static handgrip exercise, and by 90 (SD 67)% during posthandgrip ischemia. The study clearly indicates a facilitation of the short-latency stretch reflex during increased sympathetic outflow. We note that the enhanced stretch reflex responses observed in relaxed muscles in the absence of skeletomotor activity support the idea that the sympathetic nervous system can exert a direct influence on the human muscle spindles.
Medical Genetic Services in the State of Rio de Janeiro, Brazil
Authors: Horovitz Dafne Dain Gandelman , de Mattos Ruben Araújo , Llerena Jr Juan Clinton
Published: November 2004

Rio de Janeiro is a state with close to 15 million inhabitants and approximately 250,000 births per year. The state counts nine clinical genetic units in public institutions, providing for 9,400 outpatient consultations yearly, which is insufficient to cover the estimated needs. Laboratory tests such as cytogenetics, inborn errors of metabolism and molecular studies are available on a limited basis. Newborn screening in the public health system is being performed for phenylketonuria, congenital hypothyroidism and sickle cell disease. In the state there are also special treatment programs for osteogenesis imperfecta and Gaucher’s disease, subsidized by the Brazilian Ministry of Health. Presently, efforts of medical geneticists are concentrated on highlighting the practical relevance of clinical genetics, and the need to integrate the specialty into the public health system in a functional network of genetic services.
Genetic Services and Research in the State of Minas Gerais, Brazil
Authors: Aguiar Marcos José Burle
Published: November 2004

The state of Minas Gerais in Brazil has a surface of 586,528 km2, and 18 million inhabitants. Infant mortality rate is 20/1,000, and congenital anomalies are its second cause. There are 11 medical schools where basic genetics, but not clinical genetics, is taught. Genetic services in the state include: newborn screening for hypothyroidism, phenylketonuria, sickle cell disease and cystic fibrosis; clinical-genetic diagnostic evaluation and counseling; prenatal diagnosis, fetal medicine and paternity testing. Medical genetic services and research are underdeveloped because of limitations such as lack of health policies in genetics, small number of trained specialists, little knowledge about genetics among health professionals and low reimbursement rates.
Genetic Services in Chile
Authors: Taucher Silvia Castillo
Published: November 2004

Demographic changes in Chile have positioned congenital malformations as a major cause of infant morbidity and mortality. At the same time, medical genetics has become increasingly important in relation to the diagnosis and management of individuals with birth defects and hereditary conditions as well as in the study of pathological pregnancies and reproductive problems. In addition, recent advances in genomic research are expanding the relevance of medical genetics to medicine as a whole. This article reviews the clinical genetic resources currently available in Chile; the teaching of genetics in undergraduate, graduate, and continued medical education; some relevant interventions that have taken place in our country, e.g. the expansion of the newborn screening program and the initiation of a folic acid fortification program, and recent efforts to enhance population access to clinical genetics services.
Genetic Services in Ecuador
Authors: Paz-y-Miño César
Published: November 2004

Ecuador has a population of 12 million inhabitants, composed of a variety of ethnic groups. The majority of the population lives in rural areas. There is a severe deficiency in health services, and most diseases are associated with poor life conditions: malnutrition, parasitic diseases and infections. At the same time, however, chronic diseases, e.g. cancer, have increased in prevalence. Most genetic services are provided by the private sector, which offers clinical genetic consultations and counseling, cytogenetic analyses, a limited number of molecular and biomedical tests, and prenatal diagnosis. Genetic research is centered in the universities of important cities (Quito, Guayaquil and Cuenca). The government sponsors some university research projects but does not conduct health actions in genetics in the community. There is an incipient interest in ethic and legal issues in genetics, such as how to provide modern genomic medicine in a resource-poor country.
Genetic Services in Mexico City
Authors: Kofman-Alfaro Susana , Zenteno Juan Carlos
Published: November 2004

In the year 2002, the population of Mexico was approaching 103 million inhabitants. Approximately 74% of them live in the cities with a continuous migration from rural to urban areas. Genetic departments are concentrated in the capital and other big cities. In this paper we review the current status of genetic departments in Mexico City, emphasizing the main areas of genetic services offered to the public and involved in research. We also comment on the deficiencies identified and suggest recommendations to improve the quality of the genetic services offered to the Mexican population.
Do We Need to Perform Cystoscopy on All Adults Attending Urology Centres as Outpatients?
Authors: Kumar V. , Patel H.R. , Nathan S.M. , Miller R.A. , Lawson A.H.
Published: November 2004

Introduction: There has been considerable expansion in the use of flexible cystoscopy (FC) and people who can perform the procedure. Hence, there is a criticism that this procedure is being overused with no management benefit. Materials and Methods: We audited the use of FC in a district hospital for a period of 1 year. The results of FC for non-standard indications (other than haematuria and check cystoscopy) were analysed for their diagnostic yield. Results: Of the 1,390 FCs performed, 295 were done for non-standard indications. 46.14% of these cystoscopies had positive findings. Cancer detection rate was 6.10%. Cystoscopy altered the management in 14.08% of patients and was supportive to diagnosis and management in 32.06%. Conclusion: This procedure is certainly not overused and the ever-increasing requirement of this simple procedure has serious resource implications for the National Health Service.
Bladder Tumor Recurrence after Primary Surgery for Transitional Cell Carcinoma of the Upper Urinary Tract
Authors: Oehlschläger S. , Baldauf A. , Wiessner D. , Gellrich J. , Hakenberg O.W. , Wirth M.P.
Published: November 2004

Objective: Primary transitional cell carcinoma (TCC) of the upper urinary tract represents 6–8% of all TCC cases. Nephroureterectomy with removal of a bladder cuff is the treatment of choice. The rates of TCC recurrence in the bladder after primary upper urinary tract surgery described in the literature range between 12.5 and 37.5%. In a retrospective analysis we examined the occurrence of TCC after nephroureterectomy for upper tract TCC in patients without a previous history of bladder TCC at the time of surgery. Methods: Between 1990 and 2002, 29 patients underwent primary nephroureterectomy for upper tract TCC. The mean age of the patients was 69.5 years. In 5 cases upper urinary tract tumors were multilocular, in the remaining cases unilocular in the renal pelvis (n = 12) or the ureter (n = 12). The follow-up was available for 29 patients with a mean follow-up of 3.37 (0.1–11.2) years. Results: 11/29 (37.9%) patients had TCC recurrence with 9/11 patients having bladder TCC diagnosed within 2.5 years (0.9–6.0) after nephroureterectomy. 13/29 patients are alive without TCC recurrence, 3/29 patients died due to systemic TCC progression and 5/29 died of unrelated causes without evidence of TCC recurrence. Conclusion: Our data indicate a high incidence of bladder TCC after nephroureterectomy for primary upper tract TCC of up to 6 years after primary surgery. Because of the high incidence of bladder TCC within the first 3 years of surgery, careful follow-up is needed over at least this period.
p53 Gene Mutations in Superficial Bladder Cancer
Authors: Lorenzo Romero J.G. , Salinas Sánchez A.S. , Giménez Bachs J.M. , Sánchez Sánchez F. , Escribano Martínez J. , Hernández Millán I.R. , Segura Martín M. , Virseda Rodríguez J.A.
Published: November 2004

Objectives: To assess the presence of p53 gene mutations in superficial tumors of the urinary bladder (transitional cell carcinoma) and their relationship to classic prognostic factors for cancer recurrence and progression. To analyze the implication of these mutations on the P53 protein structure. Materials and Methods: Observational, cross-sectional study of 90 consecutive patients, 60 with superficial transitional cell carcinoma (pTa and pT1) and 30 without neoplastic disease (control group). Samples of bladder tumor and control normal mucosa were analyzed by polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) to detect p53 mutations in exons 5–9. Automatic sequencing was used to characterize the mutations and their effect on the P53 protein was analyzed. Bivariate analysis was used to assess the association with other prognostic factors. Results: PCR-SSCP found no mutations in any control group patient, whereas 38.3% of patients with superficial transitional cell carcinoma had one or more mutations in the exons analyzed. Thirty mutations were sequenced; all were point mutations and 86.67% were considered relevant for the P53 structure. A total of 93.3% of the mutations were located in highly conserved regions and 73.3% in mutational hot spots. The highest cell differentiation grades and pT1 stage were associated with a higher incidence of p53 gene mutations. Previous recurrences and other tumor-related histological variables were not associated with a higher percentage of mutations. Conclusion: Mutations at p53 did not appear in healthy bladder mucosa and were significantly more frequent in pT1 and high-grade (G-II and G-III) tumors. All mutations detected were point mutations and most caused considerable P53 structural abnormalities, implying major repercussions on P53 function. These data suggest that certain p53 mutations may have prognostic value, even though they were not associated with other classic recurrence and tumor progression parameters. Future analyses of the progress of patients with superficial bladder transitional cell carcinoma and mutated p53 will help clarify this aspect.
Extracorporeal Shockwave Lithotripsy Compared with Ureteroscopy for the Removal of Small Distal Ureteral Stones
Authors: Hautmann Stefan , Friedrich Martin G. , Fernandez Salvador , Steuber Thomas , Hammerer Peter , Braun Peter Martin , Jünemann Klaus-Peter , Huland Hartwig
Published: November 2004

Introduction: The treatment of small distal ureteral stones smaller or equal to 5 mm in size is still highly controversial. In distal ureteral stones larger than 5 mm in size, ureteroscopy (URS) has been shown in many studies to be superior to shockwave lithotripsy (SWL). The objective was to analyze the stone-free rate after treatment of distal ureteral stones with in situ SWL or URS. Materials and Methods: A total of 3,857 SWL treatments were performed at our institution between 1996 and 2001. During this period 45 in situ SWL procedures were performed with the Dornier MFL 5000 lithotripter on distal ureteral stones regardless of the stone size. A total of 262 URS treatments were performed on distal ureteral stones. URS for small (5 mm or less) distal ureteral stones was performed in 110 cases. Results: Distal ureteral stones smaller or equal to 5 mm in size were treated successfully stone free in 78% in one SWL session. Patients required a second SWL in 14% of the cases and 8% of the patients required a third SWL session. URS patients were successfully stone free after the procedure in 97% of the cases. Failed URS that needed an additional URS were performed in 2 and 1% of the patients had one SWL in situ treatment. Conclusions: URS treatment has shown to be the therapy of choice for distal ureteral stones. It is more effective than SWL treatment in this stone location. In experienced hands URS is a safe though even more invasive procedure than SWL. This can be expected as urologists perform more than 40 URS procedures per year.
Hemostasis in Tubeless PNL: Point of Technique
Authors: Aron Monish , Goel Rajiv , Kesarwani Pawan K. , Gupta Narmada P.
Published: November 2004

Introduction: Tubeless PNL (percutaneous nephrolithotomy), in a highly selected group of patients, is a modification aimed at reducing the morbidity of PNL. We present a simple technique of achieving tract hemostasis as an adjunct to the safe performance of a tubeless PNL. Materials and Methods: Charts of 40 consecutive patients who underwent tubeless PNL at our center were reviewed. In the latter 20 consecutive patients, diathermy coagulation of the intrarenal bleeders and tract was done and these patients were compared with the earlier 20 patients in whom fulguration was not done. Drop in hemoglobin, postoperative analgesic requirement, operating time, length of hospitalization and postoperative complications were compared. Results: No statistical difference was found between the operative times and drop in hemoglobin for both the groups. The length of hospitalization and postoperative analgesic requirement were significantly less in the fulguration group. No significant complications were noted in either of the two groups. Conclusions: Fulguration of visible intrarenal and tract bleeders is a simple, safe and effective hemostatic adjunct in patients undergoing tubeless PNL.
Gyrus Plasmasect: Is It Better than Monopolar Transurethral Resection of Prostate?
Authors: Yang Stone , Lin Wen-Chou , Chang Huang-Kuang , Hsu Jong-Ming , Lin Wun-Rong , Chow Yung-Chiong , Tsai Wei-Kung , Lee Te-An , Lo King-Yik , Chow Ko , Chen Marcelo
Published: November 2004

Introduction: This randomized prospective study was conducted to compare the efficacy and safety of the Gyrus Plasmasect loop bipolar transurethral resection of prostate (TURP) and conventional monopolar TURP in the treatment of benign prostatic hyperplasia (BPH). Materials and Methods: A total of 117 men were enrolled in this study. Fifty-eight patients underwent Gyrus Plasmasect TURP and 59 patients underwent monopolar TURP. They were followed up for 3 months after surgery. Results: Significant improvements were seen postoperatively in both the Gyrus and monopolar groups in terms of prostatic volume, International Prostate Symptom Score, quality of life score, peak flow rate, and post-void residual urine volume. However, the degree of improvement was not statistically different between the 2 groups. Significantly less blood loss, shorter postoperative catheterization time and length of hospital stay were seen in the Gyrus group. Conclusions: Gyrus Plasmasect TURP yielded comparable results to monopolar TURP; however, this is only a preliminary study and follow-up is necessary to assess its long-term efficacy.
Localized Primary Amyloidosis of the Genitourinary Tract: Does Conservatism Help?
Authors: Zaman Waheed , Singh Vishwajeet , Kumar Binay , Mandhani Anil , Srivastava Aneesh , Kumar Anant , Kapoor Rakesh
Published: November 2004

Primary amyloidosis of the genitourinary tract is a rare clinical entity with an excellent prognosis in most cases. It is of interest to the urologist as it mimics malignancy. The definitive diagnosis is made on histologic examination and by excluding secondary causes of amyloidosis. We present 4 patients with primary localized amyloidosis of the genitourinary tract who were treated with transurethral resections alone with satisfactory outcome.