bluuebunny/crossref_metadata_2025_split huggingface dataset:
Repeatability of standard metabolic rate and gas exchange characteristics in a highly variable cockroach,Perisphaeriasp.
Authors: Marais Elrike , Chown Steven L. 
Published: November 2003

SUMMARYFor natural selection to take place several conditions must be met,including consistent variation among individuals. Although this assumption is increasingly being explored in vertebrates, it has rarely been investigated for insect physiological traits, although variation in these traits is usually assumed to be adaptive. We investigated repeatability (r) of metabolic rate and gas exchange characteristics in a highly variable Perisphaeriacockroach species. Although this species shows four distinct gas exchange patterns at rest, metabolic rate (r=0.51) and the bulk of the gas exchange characteristics (r=0.08–0.91, median=0.42) showed high and significant repeatabilities. Repeatabilities were generally lower in those cases where the effects of body size were removed prior to estimation of r. However, we argue that because selection is likely to act on the trait of an animal of a given size, rather than on the residual variation of that trait once size has been accounted for, size correction is inappropriate. Our results provide support for consistency of variation among individuals, which is one of the prerequisites of natural selection that is infrequently tested in insects.
Na+/K+-ATPase α-isoform switching in gills of rainbow trout (Oncorhynchus mykiss) during salinity transfer
Authors: Richards Jeff G. , Semple Jeffrey W. , Bystriansky Jason S. , Schulte Patricia M. 
Published: November 2003

SUMMARYWe identified five Na+/K+-ATPase α-isoforms in rainbow trout and characterized their expression pattern in gills following seawater transfer. Three of these isoforms were closely related to other vertebrate α1 isoforms (designated α1a, α1b and α1c),one isoform was closely related to α2 isoforms (designated α2) and the fifth was closely related to α3 isoforms (designated α3). Na+/K+-ATPase α1c- and α3-isoforms were present in all tissues examined, while all others had tissue specific distributions. Four Na+/K+-ATPase α-isoforms were expressed in trout gills (α1a, α1b, α1c and α3). Na+/K+-ATPase α1c- and α3-isoforms were expressed at low levels in freshwater trout gills and their expression pattern did not change following transfer to 40% or 80% seawater. Na+/K+-ATPase α1a and α1b were differentially expressed following seawater transfer. Transfer from freshwater to 40% and 80% seawater decreased gill Na+/K+-ATPaseα1a mRNA, while transfer from freshwater to 80% seawater caused a transient increase in Na+/K+-ATPase α1b mRNA. These changes in isoform distribution were accompanied by an increase in gill Na+/K+-ATPase enzyme activity by 10 days after transfer to 80% seawater, though no significant change occurred following transfer to 40% seawater. Isoform switching in trout gills following salinity transfer suggests that the Na+/K+-ATPase α1a- andα1b-isoforms play different roles in freshwater and seawater acclimation, and that assays of Na+/K+-ATPase enzyme activity may not provide a complete picture of the role of this protein in seawater transfer.
Loss of gustatory responses to pyrrolizidine alkaloids after their extensive ingestion in the polyphagous caterpillar Estigmene acrea
Authors: Bernays E. A. , Rodrigues D. , Chapman R. F. , Singer M. S. , Hartmann T. 
Published: November 2003

SUMMARY
Electrophysiological recordings from taste sensilla of the caterpillar Estigmene acrea with the pyrrolizidine alkaloid (PA) seneciphylline N-oxide demonstrated that extensive feeding on plants rich in PAs caused a loss in response of the PA-sensitive cell in the lateral styloconic sensillum on the galea. The effect could be repeated using pure PAs fed to the insect in synthetic diets and by injection of PA into the hemolymph. The sensitivity loss lasted for approximately two hours and was less pronounced in individuals that had been reared on PA-containing food. Behavioral experiments and field observations demonstrate a parallel reduction in responsiveness to PAs and to PA-containing plants.
Influences of thermal acclimation and acute temperature change on the motility of epithelial wound-healing cells (keratocytes) of tropical,temperate and Antarctic fish
Authors: Ream Rachael A. , Theriot Julie A. , Somero George N. 
Published: November 2003

SUMMARYThe ability to heal superficial wounds is an important element in an organism's repertoire of adaptive responses to environmental stress. In fish,motile cells termed keratocytes are thought to play important roles in the wound-healing process. Keratocyte motility, like other physiological rate processes, is likely to be dependent on temperature and to show adaptive variation among differently thermally adapted species. We have quantified the effects of acute temperature change and thermal acclimation on actin-based keratocyte movement in primary cultures of keratocytes from four species of teleost fish adapted to widely different thermal conditions: two eurythermal species, the longjaw mudsucker Gillichthys mirabilis (environmental temperature range of approximately 10-37°C) and a desert pupfish, Cyprinodon salinus (10-40°C), and two species from stable thermal environments, an Antarctic notothenioid, Trematomus bernacchii(-1.86°C), and a tropical clownfish, Amphiprion percula(26-30°C). For all species, keratocyte speed increased with increasing temperature. G. mirabilis and C. salinus keratocytes reached maximal speeds at 25°C and 35°C, respectively, temperatures within the species' normal thermal ranges. Keratocytes of the stenothermal species continued to increase in speed as temperature increased above the species'normal temperature ranges. The thermal limits of keratocyte motility appear to exceed those of whole-organism thermal tolerance, notably in the case of T. bernacchii. Keratocytes of T. bernacchii survived supercooling to -6°C and retained motility at temperatures as high as 20°C. Mean keratocyte speed was conserved at physiological temperatures for the three temperate and tropical species, which suggests that a certain rate of motility is advantageous for wound healing. However, there was no temperature compensation in speed of movement for keratocytes of the Antarctic fish, which have extremely slow rates of movement at physiological temperatures. Keratocytes from all species moved in a persistent,unidirectional manner at low temperatures but at higher temperatures began to take more circular or less-persistent paths. Thermal acclimation affected the persistence and turning magnitude of keratocytes, with warmer acclimations generally yielding more persistent cells that followed straighter paths. However, acclimation did not alter the effect of experimental temperature on cellular speed. These findings suggest that more than one temperature-sensitive mechanism may govern cell motility: the rate-limiting process(es) responsible for speed is distinct from the mechanism(s) underlying directionality and persistence. Keratocytes represent a useful study system for evaluating the effects of temperature at the cellular level and for studying adaptive variation in actin-based cellular movement and capacity for wound healing.
Carrierless Amplitude–Phase Modulation
Authors: Saltzberg Burton R. 
Published: November 2003

Abstract
Carrierless Amplitude‐Phase Modulation (CAP) is a two‐dimensional digital modulation system very similar to Quadrature Amplitude Modulation (QAM). As in QAM, the modulated signal consists of two passband signals occupying the same spectrum. Instead of using explicit modulation by a pair of quadrature carriers as in QAM, CAP achieves orthogonality by passing the data signals through a pair of band‐pass filters which constitute a Hilbert pair. CAP has found application particularly in Digital Subscriber Line systems.
High‐Rate Punctured Convolutional Codes
Authors: Haccoun David 
Published: November 2003

AbstractThis chapter presents high‐rate punctured convolutional codes. Perforation matrices, weight spectra and upper bounds on the bit error probability of the best known punctured codes having memory 2 ≤ M ≤ 8, and coding rates 2/3 ≤ R ≤ 7/8 are provided. Rate‐2/3 and 3/4 long‐memory punctured convolutional codes with 9 ≤ M ≤ 23 are provided together with the leading terms of their weight spectra and their bit error performance bounds.
Trends in Wireless Indoor Networks
Authors: Pahlavan K. , Beneat J. , Li X. 
Published: November 2003

AbstractThis chapter provides an overview of the trends in wireless indoor networks. Since the late 1970's when the concept of wireless LAN was first introduced, this area has gone through significant ups and downs. After a very exciting development period in the late 1980's, market revenues still remained far below predictions in the mid 1990's. However, during the late 1990's with the introduction of wireless personal area networking, Bluetooth technology, and home networking, a new surge of excitement has emerged in the wireless indoor communication industry, resulting in a number of new start up projects. Furthermore in the past few years, the emergence of wireless indoor positioning systems to augment wireless indoor telecommunication services, has attracted tremendous attention to wireless indoor networks.
Frequency‐Division Multiple Access (
FDMA
): Overview and Performance Evaluation
Authors: Pavlidou Fotini‐Niovi 
Published: November 2003

Abstract
A general presentation of the Frequency Division Multiple Access Technique (FDMA) is tried. The main operation principles and the applications environment are presented first. The performance of the system is illustrated in terms of throughput and ‐noise ratio factors. The different kinds of noise affecting the system performance are described. Then, the quite numerous implementation alternatives are examined and the difference in the used terminology is investigated. A comparison with other Access Techniques is given finally with a reference list for further investigation.
Trellis Coding
Authors: Schlegel Christian 
Published: November 2003

AbstractThe tremendous growth of high‐speed logic circuits and very large‐scale integration (VLSI) has ushered in the digital information age, where information is stored, processed, and moved in digital format. in this article we discuss error control coding, which is accomplished by introducing dependencies among a large number of digital symbols. Trellis coding is a specific, widespread error control methodology.
Channel Modeling and Estimation
Authors: Tong Lang 
Published: November 2003

AbstractThe design of high performance communication systems often requires channel state information. For many applications, especially in wireless communications, such information must be obtained adaptively. In this article, a parametric model of the transmission of linearly modulated signals over a band‐limited channel is presented. Also included is an overview of various parameter estimation techniques and performance bounds of estimators under different model assumptions.
Antennas
Authors: Balanis Constantine A. , Polycarpou Anastasis C. 
Published: November 2003

AbstractThis chapter is a summary on the theory of antennas, and it has been written as an introduction for the technologist and as a review for the antenna expert. The paper traces the history of antennas and some of the most basic radiating elements, demonstrates the fundamental principles of antenna radiation, reviews Maxwell's equations, and outlines basic procedures and equations of radiation. Modeling of antenna sources excitation is illustrated, and antenna parameters and figures‐of‐merit are introduced. The basics of arrays, as well as those of adaptive arrays and smart antennas, are discussed.
Adaptive Receivers for Spread‐Spectrum Systems
Authors: Mitra Urbashi 
Published: November 2003

AbstractAdaptive demodulation algorithms for direct‐sequence code‐division multiple‐Access (DSCDMA) signaling are described herein. The article begins with a review of multiple‐access signaling and DSCDMA modulation. Several key static (nonadaptive) multiuser reception schemes are described and some basic elements of adaptive algorithms are presented. Adaptive receivers for additive white Gaussian noise channels and frequency selective fading channels are provided.
Unequal Error Protection Codes
Authors: Aksu Arda 
Published: November 2003

Abstract
The error correcting capability of the Unequal Error Protection (UEP) codes is described in terms of correcting errors in specific digits of a codeword even though other digits may be decoded incorrectly. UEP codes were first studied in [1] by Masnick and Wolf. Since then, there has been a proliferation of studies in the field of UEP codes, both in theory and in practical applications. This article provides a tutorial treatment of UEP codes and describes some applications.
Acoustic Transducers
Authors: Massa Donald P. 
Published: November 2003

Abstract
The purpose of this article is to provide a brief overview of the very extensive topic of acoustic transducers. Transducers are devices that transform one form of energy into another. We present a brief historical overview and then discuss the many factors that affect the design of an electroacoustic transducer. Next, we discuss the various transduction materials and mechanisms needed to transform electrical energy into sound and vice versa. Finally, we present several short descriptions of the construction of a few electroacoustic transducers.
Active Antennas
Authors: Mickelson Alan R. 
Published: November 2003

Abstract
An active antenna is an antenna system in which the antenna is an integral part of the circuit supplying the signal to (driving) the antenna, in transmit mode, and/or the circuit receiving the signal from the antenna is an integral part of the antenna, in the receiving mode. Such an antenna system can exhibit characteristics which are quite distinct from those exhibited by an ideal linear antenna which is electrically isolated from its feed, or read‐out, network. The first section of this article gives an historical perspective on developments in radio technology before giving a qualitative discussion of transmission line modes and antenna modes and how these modes need to relate to one and another in an active configuration. The second section of this article is quantitative and first introduces the Poynting vector in order to analyze impedance matching from an electromagnetic viewpoint before presenting a circuit theoretical discussion of oscillators and their impedance matching requirements. The third section of the article discusses some applications such as active impedance matching, parametric down conversion, power boosting, proximity detection, and active retroflection as well as quasi‐optical power combining (borrowing from array concepts introduced in the second section)
Continuous Phase Frequency Shift Keying (
CPFSK
)
Authors: Schonhoff Thomas A. 
Published: November 2003

Abstract
Continuous Phase Frequency Shift Keying (CPFSK) is a modulation that, as its name implies, can be characterized as a traditional frequency shift keyed (FSK) signal constrained to maintain continuous phase at its symbol time boundaries. This constraint offers important advantages in error rate performance as well as signal spectrum containment. In this paper, the modulation is introduced and its relationship to the more general Continuous Phase Modulation (CPM) is outlined. The spectrum of CPFSK is presented and optimal coherent and noncoherent receiver structures are developed. Finally, the coherent and noncoherent error‐rate performance of CPFSK is presented.
Optical Solitons
Authors: Karlsson Magnus , Andrekson Peter 
Published: November 2003

AbstractThe properties and history of soliton pulse propagation in optical fibers are reviewed. Both fundamental mathematical aspects are discussed as well as applied engineering issues for e.g. the generation and use of solitons in fiber‐optic communication systems. We distinguish between conventional solitons, which have a constant dispersion along the transmission, and dispersion‐managed solitons for which the dispersion varies along the transmission line. Finally the most recent soliton field experiments are reviewed and discussed.
Optical SynchronousCDMASystems
Authors: Ohtsuki Tomoaki , Sasase Iwao 
Published: November 2003

AbstractOptical CDMA systems have been investigated widely to apply for high speed LAN, because they allow multiple users to access the network simultaneously. For optical CDMA systems, both asynchronous and synchronous systems have been studied. With synchronous CDMA, the available number of signature codes is larger than that of asynchronous CDMA systems. For a given value of bit error rate, synchronous CDMA systems can accommodate more simultaneous users than asynchronous CDMA systems. Furthermore, synchronous CDMA can be efficiently used in conjunction with TDMA and WDMA on multimedia communication networks.This chapter discusses sequences, modulations, system architectures used in optical synchronous CDMA systems and their performance.
Compensation of Nonlinear Distortion inRFPower Amplifiers
Authors: Chang Sekchin , Powers Edward J. 
Published: November 2003

AbstractIn this article the concept of using predistorters to compensate for distortion associated with the saturation properties of RF power amplifiers (PAs) is described. The nonlinear input‐output characteristics of RF PAs are described, and the sensitivity of multicarrier systems, such as orthogonal frequency division multiplexing (OFDM), to nonlinear PAs is discussed. A brief overview of various predistorters is presented and the ability of a particular Volterra‐based predistorter to reduce bit error rate (BER), total degradation, and output backoff is demonstrated via a simulation experiment using a 16‐QAM‐based OFDM system.
Trellis‐Coded Modulation
Authors: Wilson Stephen G. 
Published: November 2003

AbstractTrellis‐coded modulation (TCM) is an important practical means of achieving several decibels in link efficiency on Gaussian channels, without bandwidth expansion, and is now a component of numerous wireline and wireless standards. This article surveys the important principles in the design and analysis of such encoders, provides tabulations of best codes, and illustrates with discussion of two standards employing TCM.
Reflector Antennas
Authors: Rappaport Carey 
Published: November 2003

AbstractReflector antennas are a primary means of transmitting communications signals from point‐to‐point. This section briefly summarizes the important characteristics and design considerations of reflector antennas, including farfield radiation pattern, antenna gain and beamwidth, single and dual reflectors, offset designs to prevent blockage, aperture phase errors and the effects of optical aberrations, and wide field of view scanning systems.
Path Loss Prediction Models in Cellular Communication Channels
Authors: Bertoni H. L. 
Published: November 2003

AbstractThe characteristics of the radio channel provide a challenge to the communications engineer in designing systems that are spectrally efficient so as to provide high speed services to a large numbers of subscribers. Path loss is the most basic of the channel characteristics since it influences coverage and interference predictions for any system. Because the radio links in modern wireless systems are between low base station antennas and the subscribers over relatively short paths within cities, or even inside buildings, the buildings have a major influence on the received signal. Modern systems operate at frequenciesfin the UHF (300 MHz ‐ 3 GHz) and microwave bands, so that the radio waves have wavelength λ less than a meter. Since the buildings are large compared to wavelength, it is appropriate to think of the radio waves as traveling along rays between the base station and the subscriber. Ray concepts are used in this chapter to make quantitative predictions of the path loss. These predictions are to compare well with measurements, and measurement based prediction models.
Photonic Analog‐to‐Digital Converters
Authors: Shoop Barry L. 
Published: November 2003

AbstractPhotonic A/D converters have received and continue to receive considerable attention as an alternative approach to providing increased resolution and speed in high‐performance applications. Several potential advantages of using photonics technologies come in the form of high‐speed clocking, broadband sampling, reduced mutual interference of signals, and compatibility with existing photonic‐based systems. This chapter provides an introduction, discusses progress made and present research, and provides a glimpse of several promising future architectures and technologies.
HF
Communications
Authors: Bussgang Julian J. , Parl Steen A. 
Published: November 2003

Abstract
This chapter discusses the uses and evolution of HF radio communications. The characteristics of HF radio links are summarized and the different functions and components of an HF radio terminal explained. The state of the art in HF radio modems is outlined, with emphasis on higher data rate modems. Modeling of the channel, simulation, and testing are summarized. The chapter concludes with a projection of future trends.
Synchronization in Digital Communication Systems
Authors: Luise M. , Mengali U. , Morelli M. 
Published: November 2003

AbstractReliable data detection in digital communication receivers requires that the incoming waveform be time‐aligned with certain locally generated references, namely the data clock and the sinusoidal waveforms used for demodulation. Accomplishment of this goal is referred to assynchronization(abbreviated: sync) and represents a crucial issue in the design of communication systems. Inaccurate receiver synchronization has generally catastrophic effects on the communication link performance. In addition, synchronization circuits encompass such a large part of the receiver resources that they heavily affect the overall cost.In the following we present an overview of the main synchronization functions for a large class of digitally modulated signals, including conventional (narrow‐band) modulations, direct‐sequence spread‐spectrum, and multicarrier signals. The different sync functions are split intosignalandnetworksynchronization. The former includes data clock and carrier frequency/phase recovery, and is typically carried out within the physical layer of a communication network. The latter is usually performed on digital data streams at the higher layers of the ISO/OSI stack, and deals with the time‐alignment of data frames within the format of the digital stream. As the advent of VLSI technology tends to render obsolete the analog circuits employed so far, this chapter is especially concerned with the description of digital signal processing (DSP)‐based synchronization functions.
IPTelephony
Authors: Chapman Caesar Matthew , Ghosal Dipak 
Published: November 2003

AbstractIP telephony networks have emerged as an alternative to the public switched telephone network (PSTN) for providing voice and video transport services. IP telephony systems are designed to transmit packetized voice using the Internet Protocol (IP), allowing providers the ability to bypass the PSTN and offer advanced intelligent network (AIN) services. In this article we present a detailed survey of various issues in IP telephony networks. We discuss how open protocols and architectural entities are designed, as well as how they are used in common deployment scenarios. We outline several issues of packet audio over IP networks and show how the efficient design of IP telephony network elements can significantly improve the received audio quality. IP networks may require advanced resource management and pricing strategies to offer superior quality of service (QoS) under conditions of high demand. We conclude this article with a discussion of security and regulatory issues in IP telephony networks.