bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of aging on behavior and leg kinematics during locomotion in two species of cockroach
Authors: Ridgel A. L. , Ritzmann R. E. , Schaefer P. L. 
Published: November 2003

SUMMARYAging is often associated with locomotor deficits. Behavior in aged Blaberus discoidalis cockroaches was analyzed during horizontal walking, climbing, righting and inclined walking. Adult animals showed a decrease in spontaneous locomotion with increasing age. Tarsal abnormalities,termed `tarsus catch', were often present in aged individuals. In `tarsus catch', the prothoracic leg catches on the mesothoracic leg during the swing phase. This deficit causes alterations of the gait, but animals are able to regain a tripod gait after the perturbation. The tibio-tarsal joint angle in individuals with `tarsus catch' was significantly less than in intact animals. Structural defects were consistently associated with `tarsus catch'. The tracheal tubes in the tarsus and around the tibio-tarsal joint were often discolored and the tarsal pads were hardened in aged cockroaches. All aged individuals were able to climb. However, prior to climbing, some animals with`tarsus catch' failed to show postural changes that are normally seen in young animals. Aged individuals can right as rapidly as 1-week-old adults. However,animals with `tarsus catch' take longer to right than aged intact individuals. Old cockroaches have difficulty climbing an incline of 45°, and leg slipping is extensive. Slipping may be caused by tarsal degeneration, but animals that are unsuccessful in inclined walking often show uncoordinated gaits during the attempt. Escape behavior was examined in aged American cockroaches (Periplaneta americana). They do not show normal escape. However, after decapitation, escape movements return, suggesting that degeneration in head ganglia may actually interfere with escape. These findings provide evidence for age-related changes both in the periphery and in the central nervous system of cockroaches and stress the importance of multi-level approaches to the study of locomotion.
Sensitivity Improvement in the Detection of Trichloroethylene by Applying Oxidizing Agents to the Quartz Crystal Microbalance Method
Authors: Noda Kazutoshi , Naganawa Ryuuichi , Kanekiyo Yasumasa , Tao Hiroaki 
Published: November 2003

Abstract
A new quartz crystal microbalance-based method has been developed for high-sensitivity detection of trichloroethylene. The method uses oxidizing agents such as lead dioxide and sulfuric acid, by which trichloroethylene is converted into hydrogen chloride, which in turn reacts directly with a copper electrode placed on the quartz crystal surface. The new method enables the measurement of very low concentrations of trichloroethylene, and has a detection limit comparable to the Japanese Environmental Standard (0.2 mg·m−3).
Optical Fiber Communications
Authors: Keiser Gerd 
Published: November 2003

AbstractOptical fibers are used extensively for data transmission systems because of their dielectric nature and their large information‐carrying capacity. Network architectures using multiple wavelength channels per optical fiber are utilized in local, metropolitan, or wide‐area applications to connect thousands of users having a wide range of transmission capacities and speeds. A powerful aspect of an optical communication link is that many different wavelengths can be sent along a fiber simultaneously in the 1300‐to‐1600‐ nm spectrum. The technology of combining a number of wavelengths onto the same fiber is known as wavelength division multiplexing (WDM). The concept of WDM used in conjunction with optical amplifiers has resulted in communication links that allow rapid communications between users in countries all over the world.
Maximum‐Likelihood Estimation
Authors: Haykin Simon 
Published: November 2003

AbstractThis article addresses different facets of maximum likelihood estimation. Starting with the likelihood function, the Cramér‐Rao inequality and properties of maximum likelihood estimators are described. Another estimator, namely, the conditional mean estimator, is discussed. An iterative algorithm, known as the Expectation‐Maximization (EM) algorithm, for computing the maximum likelihood estimate is described.
Sigma‐Delta Converters in Communication Systems
Authors: Harris Fred 
Published: November 2003

AbstractThe Sigma‐Delta (Σ‐Δ) converter is a source coding process that forms an enhanced‐resolution representation of a sampled data time series from a sequence of over sampled, low‐resolution measurements. The process employs three fundamental concepts, specifically, over sampling to obtain correlated samples, feedback around the quantizer to shape the noise power spectrum, and filtering to suppress the out‐of band shaped noise spectrum. The process can be applied to the task of quantizing an input analog signal, to the task or re‐quantizing an existing digital signal, or as a pre‐processor in the task of converting a digital signal to an analog signal. These tasks are commonly referred to as analog‐to‐digital conversion (A‐to‐D or ADC), digital‐to‐digital conversion (D‐to‐D or DDC), and digital‐to‐analog conversion (D‐to‐A or DAC). The Σ‐Δ converter is incorporated in many systems to enhance various signal processing and signal conditioning tasks commonly present in modern modem designs. In this section we present the fundamentals of the sigma‐delta converter, introduce a variety of implementation options, and demonstrate typical performance curves. We also illustrate a number of standard and unconventional applications of the Σ‐Δ converter in contemporary communication systems.
Concatenated Convolutional Codes and Iterative Decoding
Authors: Ryan William E. 
Published: November 2003

AbstractTurbo codes, first presented to the coding community in 1993, represent one of the most important breakthroughs in coding since Ungerboeck introduced trellis codes in 1982. This chapter presents a tutorial exposition of parallel and serial concatenated convolutional codes (PCCCs and SCCCs). Included here are a simple derivation for the performance of these codes and a straightforward presentation of their iterative decoding algorithms. A detailed description of soft‐input/soft‐output (SISO) decoding based on the BCJR algoithm is given, both in the probability domain and in the log domain. The iterative (turbo) decoding algorithm which employs SISO decoders as component decoders is also described in detail for PCCCs and SCCCs. The treatment is intended to be a launching point for further study in the field and to provide sufficient information for the design of computer simulations.
MIMOCommunication Systems
Authors: Nabar Rohit U. , Paulraj Arogyaswami J. 
Published: November 2003

Abstract—MIMO technology is an emerging area that promises significant improvements in coverage and capacity of wireless networks. In this chapter, we review this rapidly developing technology. We present the key leverages of MIMO–array gain, diversity gain, multiplexing gain and interference reduction and provide insights into how these gains may be utilized to improve the quality of wireless communication. We introduce a simple MIMO channel model for flat fading conditions in an interference free environment and present previously derived capacity results for MIMO systems that hint to a significant capacity advantage. We discuss the broad goals of MIMO signaling (multiplexing vs diversity), the tradeoffs in receiver design for various signaling schemes and coding and modulation techniques for MIMO. Finally, we conclude with a list of emerging research areas in the field of MIMO communication systems.
Peak‐to‐Average Power Ratio of Orthogonal Frequency‐Division Multiplexing
Authors: Tellambura Chintha , Parker Matthew G. 
Published: November 2003

AbstractOFDM techniques have been proposed for digital TV broadcasting and high speed wireless networks over multipath channels. One of the principal disadvantages of OFDM is the occurrence of high peak to average power ratios. This article examines the statistical distribution of PAR, computational methods and several PAR reduction methods.
Chaos in Communications
Authors: Yao Kung , Chen Chi‐Chung 
Published: November 2003

AbstractThis paper examines the roles in which chaos have been used in various approaches in communications. In the first approach, instead of modulating a periodic sinusoidal carrier as in conventional communications, various forms of modulation using an aperiodic chaotic waveform have been proposed. They include chaotic masking, dynamical feedback, chaotic switching, and different versions of chaos shift keying. Since these continuous‐time chaotic digital communication systems are modeled as stochastic nonlinear dynamical systems, the error probabilities of many of these systems do not have analytically tractable forms, but must be numerically evaluated using Ito/Stratonovich stochastic integrations. In the second approach, symbolic dynamics viewed as a “coarse‐grained” description of a chaotic dynamical system is exploited for modulating/coding of digital data. In the third approach, chaotic dynamics are viewed as analog channel encoders. In the fourth approach, communications using chaotic pulse‐position‐modulation are discussed. In the fifth approach, CDMA communication systems using spread sequences generated from chaotic dynamics are considered. Finally, in the sixth approach, the roles of chaos in laser communication and modeling of RF propagation effects for clutter and fading channel are discussed. Some comments are also provided on the practicality of various chaos‐based communication schemes.
Design and Analysis of Low‐Density Parity‐Check Codes for Applications to Perpendicular Recording Channels
Authors: Kurtas Erozan M. , Kuznetsov Alexander V. , Vasic Bane 
Published: November 2003

AbstractIn this paper we introduce a novel class of a very high‐rate low‐density parity check codes and analyze their performance in a perpendicular magnetic recording system. Our codes are well‐structured and, unlike random codes, can lend themselves to a very low complexity implementation for high speed applications.
Horn Antennas
Authors: Jull Edward V. 
Published: November 2003

AbstractThe development of horns as antennas, array elements and reflector feeds is outlined. Expressions for the vector radiation fields of open‐ended rectangular and circular waveguides and pyramidal, sectoral and conical horns are given. Some far field radiation patterns and formulas for near and far field axial gain are shown. Dual‐mode, conical and profile horns are illustrated and their advantages as feeds for reflector antennas described. The phase centers of certain horns are defined. The importance of horn impedance is indicated and a few typical VSWR values are given.
Power Control in
CDMA
Cellular Communication Systems
Authors: Rintamäki Matti 
Published: November 2003

Abstract
Transmitter power control (TPC) is an essential radio resource management function in CDMA cellular communication systems. Since in CDMA the users share the same frequency band simultaneously, any unnecessary increase in transmitter powers will increase the interference seen by all other users. Thus it is important to minimize the transmitter powers while at the same time providing the users with sufficient quality of service (QoS). Merely finding a suitable power level initially for each transmitter is not sufficient, since the wireless radio environment changes all the time. Therefore, a TPC algorithm needs to be able to adapt to the changes in the radio channel conditions. Furthermore, the next generation in cellular communication systems will provide various services, including real‐time and non‐real‐time services with various data rates. The different service types lead to different, and even conflicting, solutions to efficient TPC.
Vocoders
Authors: Spanias Andreas 
Published: November 2003

AbstractIn the last decade we have witnessed substantial progress towards the application of vocoders in communications and multimedia. Vocoders are typically based on a source‐system model whose parameters are encoded in a compact binary format. The objective in voice or speech coding is to represent speech with a minimum number of bits while preserving its perceptual quality. A number of vocoders are embedded in cellular and multimedia standards. The objective of this chapter is to provide a review of vocoding algorithms with emphasis on those methods that are part of telephony standards
ModernEthernet Technologies
Authors: Lam Cedric F. 
Published: November 2003

AbstractEthernet has emerged from a multiple access protocol used in a local area environment to a ubiquitous transport technology reaching into metro and wide area networks. The technology and architecture of Ethernet has gone through many changes since it was invented in the 1970s. This paper reviews the latest development of Ethernet technologies. Section 1 introduces the Ethernet development trend. Section 2 reviews the general Ethernet concepts, which include architecture of Ethernet with respect to the OSI reference model, Ethernet MAC frame format, Ethernet addressing schemes, the CSMA/CD protocol and the concept of repeaters. Modern Ethernet is based on a hubbed architecture in which stations are connected to a switch hub. Functions of Ethernet switches are discussed in Section 3. Section 4 covers the development of the Ethernet physical layer and the technologies used to implement Ethernet devices. Section 5 is devoted to 10Gigabit Ethernet which is the latest Ethernet Standard involving advanced fiber optic technologies. In section 6, we discuss the work on Ethernet for the First Mile (EFM) that the IEEE802.3 Standard Group has initiated for the purpose of providing Ethernet services through economical copper and optical fiber access networks. The research work on Ethernet Passive Optical Networks (EPON) has been discussed in detail in this section. Section 7 concludes the paper.
Multidimensional Codes
Authors: Shea John M. , Wong Tan F. 
Published: November 2003

AbstractIn this chapter we provide a brief introduction to multidimensional codes. In particular, we focus on product codes and other similar codes that use parity checks over multidimensional arrays. We present a brief introduction to product codes and their properties. We then focus on multidimensional codes based on single parity‐check constituent codes. We provide two applications that illustrate that these codes can be useful in achieving performance close to the channel capacity.
Nonuniformly Spaced Tapped‐Delay‐Line Equalizers For Sparse Multipath Channels
Authors: Lee Frederick K. H. , McLane Peter J. 
Published: November 2003

AbstractThis article presents a general overview on the use of nonuniformly spaced tapped‐delay‐line equalizers (NU‐Es) as a reduced‐complexity technique for a class of dispersive channels called sparse multipath channels. Advantages of using NU‐Es over conventional uniformly‐spaced tapped‐delay‐line equalizers are discussed, and existing methodologies for designing finite‐length NU‐Es are reviewed, with detailed elaboration of a design approach based on infinite‐length equalizers. Performance and properties of the finite‐length NU‐Es are demonstrated via a practical example.
Chirp Modulation
Authors: Dahlhaus Dirk 
Published: November 2003

AbstractThe fundamentals of chirp modulation (CM) for spread spectrum signaling in a communication system are presented. Properties of CM signals like the representation in the time and frequency domains, the correlation functions of upchirp and downchirp signals arising in the context of matched filtering and sidelobe reduction techniques are discussed in detail. Modulation schemes including linear and nonlinear modulation as well as multiple access schemes are described and analyzed in terms of the resulting bit‐error rates. The comparison of different implementation methods is followed by a discussion of other aspects related to CM in communcation systems.
Low‐Density Parity‐Check Codes: Design and Decoding
Authors: Johnson Sarah J. , Weller Steven R. 
Published: November 2003

AbstractIn this chapter, we treat code design and decoding for a family of error correction codes known as low‐density parity‐check (LDPC) codes. The chapter begins with an introduction to error correction in telecommunications with the focus on parity‐check equations and codes defined by their parity‐check matrices. To introduce the concepts behind iterative decoding, a hard‐decision iterative algorithm is discussed before the soft‐decision sum‐product decoding algorithm is presented. Following sections focus on the relationship of graph‐based representations of codes to the development of both the theoretical understanding and implementation of iterative decoders, and current methods for design of LDPC codes. The chapter concludes with the connections of LDPC codes and their decoding to other topics and likely future directions in the area.
Photonic Crystal Fibers
Authors: Tajima Katsusuke 
Published: November 2003

AbstractA photonic crystal fiber (PCF), which is composed of small air holes running through the fiber length, has various kinds of unique features that cannot be realized in a standard single‐mode fiber. We cannot expect more advancement in optical fiber optics without PCFs.In this article, various important properties such as dispersion, mode‐field diameter, and the single‐mode property are reviewed. Also, applications such as dispersion‐compensating fibers, supercontinuum, and polarization‐maintaining fibers are explained.
Economic Issues of
US
Agricultural Pesticide Use
Authors: Osteen Craig , Padgitt Merritt 
Published: November 2003

Abstract
The use of synthetic organic pesticides in US agriculture grew dramatically from the late 1940s until the early 1980s, stabilized in the 1980s, and increased at a much slower rate through the 1990s. The extent of pesticide use responded to market factors, such as price trends, which affected crop acreage and encouraged use of more cost‐effective inputs, but also to farm programs. The development of genetically modified crops, if accepted by consumers and regulators, may influence future pesticide use trends, crop yields, and pest control costs. Increased pesticide use led to concerns about counterproductive effects on pest control, such as increased pest resistance. Scientists developed the concepts of integrated pest management (IPM) and economic thresholds to eliminate unnecessary pesticide applications and encourage nonpesticide practices where economically feasible. Increased pesticide use also led to controversies about food safety, water quality, worker safety, and wildlife mortality. These concerns, and changing societal attitudes emerging in the 1960s, resulted in a series of laws, including the Food Quality Protection Act of 1996, that changed the regulatory process to emphasize protection from pesticide hazards. The regulatory process affects pesticide use by influencing the development of pesticides, registering new materials, and removing others from the market.
Fungicides, Cymoxanil
Authors: Joshi Madan M. 
Published: November 2003

Abstract
Cymoxanil is a unique cyanoacetamide fungicide that is used extensively in combination with other fungicides to control downy mildews of grapes, potatoes, vegetables, and several other crops. It displays preventive, curative, penetrant, and local systemic activity on treated plants. In the target pathogen, cymoxanil inhibits synthesis of nucleic acids, amino acids, and other cellular processes. Cymoxanil is safe to mammals and nontarget plants, animals, and microorganisms. It is metabolized rapidly and extensively in animals, plants, and environment. Combining cymoxanil with fungicides belonging to different modes of action has helped prevent the selection of strains of pathogens resistant to this fungicide.
Skeletal pathology in a prehistoric Pacific Island sample: Issues in lesion recording, quantification, and interpretation
Authors: Buckley H.R. , Tayles N. 
Published: November 2003

AbstractThis paper presents a profile of evidence of disease in a skeletal sample from Taumako Island, Southeast Solomon Islands, Melanesia, and aims to increase awareness of the prehistoric Pacific Island disease environment. It also addresses issues of lesion recording, quantification, and interpretation. Two methodologies for the determination of lesion prevalence were applied, one based on prevalence in observable individuals and one in skeletal elements. The aim of these methodologies was to provide objective data on skeletal lesions in this sample, with transparency in methods for application in comparative studies. The types of lesions observed were predominantly osteoblastic and affecting multiple bones, particularly in the lower limbs. The individual analysis yielded a prevalence of lesions affecting 56.4% of the postcranial sample from birth to old age. As expected, the skeletal element analysis yielded a lower prevalence, with 15.0% of skeletal elements affected. The skeletal element analysis also revealed a pattern of greater lower limb involvement, with a predilection for the tibia. The pattern of skeletal involvement was similar in both analyses, suggesting the validity of employing either method in paleopathological studies. A differential diagnosis of the lesions included osteomyelitis, treponemal disease, and leprosy. Metabolic disease was also considered for subadult lesions. Based on lesion type, skeletal distribution, and epidemiology of lesions in the sample, an etiology of yaws (Treponema pertenue) was suggested as responsible for nearly half the adult lesions, while multiple causes, including yaws, were suggested for the lesions in subadults. Am J Phys Anthropol, 2003. © 2003 Wiley‐Liss, Inc.
Reliability and variability of bioimpedance measures in normal adults: Effects of age, gender, and body mass
Authors: Dittmar Manuela 
Published: November 2003

AbstractThis study aimed to analyze the reliability and evaluate the causes of variability of bioimpedance parameters. Direct measures were analyzed because they are not affected by inappropriate prediction models. Resistance (R), reactance (Xc), and phase angle (PA) were determined at three fixed frequencies (5, 50, and 100 kHz) in 653 normal Germans (244 males and 409 females), aged 20–90 years, using a phase‐sensitive whole‐body tetrapolar bioimpedance analyzer (BIA 2000‐M, Data Input, Germany). From these values, six bioimpedance ratios were calculated (R5/R50, R5/R100, Xc5/Xc50, Xc5/Xc100, PA5/PA50, and PA5/PA100). Reliability of duplicate measurements, as determined by technical error, is high. ANOVA for repeated measurements yields a significant frequency main effect (within‐subjects factor) and significant effects of age and gender (between‐subject factors) on variation of resistance, reactance, and phase angle. Multiple regression analyses indicate independent effects of age, gender, and body mass index on variability of resistance, reactance, and phase angle at the three frequencies. Gender primarily influences variation in resistance (smaller values in males), whereas age mainly affects variations in reactance and phase angle (smaller values in older adults). Obesity is associated with smaller resistance (at all frequencies) and smaller reactance (high frequencies), but larger phase‐angle values (low frequency). The study shows that variability of direct bioimpedance measures depends on age, gender, and body mass characteristics of the study population. The potential benefit for using both low and high frequencies in R measures is to differentiate between extra‐ and intracellular fluid spaces, which may be altered during human growth and aging. Am J Phys Anthropol,121:000 – 000,2003. © 2003 Wiley‐Liss, Inc.