bluuebunny/crossref_metadata_2025 huggingface dataset:
ORGANO-HALOGEN USES FOR CONTROLLED CUTTING OF CARBON NANOTUBES
Authors: EL-HAMI KHALIL , MATSUSHIGE KAZUMI
Published: November 2003

A novel method of precise and controlled cutting of CNTs into pieces is presented in this letter. Sidewalls of CNTs covered by an organo-halogen such as polyvinylidene fluoride and trifluoroethylene P(VDF/TrFE) were cut by conventional transmission electron microscopy. Bombardment of CNT/P(VDF/TrFE) nanocomposite with an energetic TEM electron beam was found to effect a breakage of the molecular chain bonds of the P(VDF/TrFE) copolymer. This is due to the creation of instability and weakness under electron beam bombardments. The copolymer is locally heated and decomposed. During this process, radicals and instantaneous new bonds of HF gas, which is strong acid, were formed. Predominating chemical reactions attack and open the CNT's bonds. With this reproducible and controllable method1 desirable lengths of CNT could be obtained with an error estimated at ±3 nm. The P(VDF/TrFE) layer could play a further role in protecting and isolating CNTs in electronic circuits.
IMPROVEMENT IN SEPARATION OF NANOSTRUCTURED CARBON CLUSTERS C60 AND C70
Authors: JOVANOVIC T. , KORUGA Dj. , JOVANCICEVIC B. , SIMIC-KRSTIC J.
Published: November 2003

We used carbon soot produced by electrical arc method. Fullerenes, mainly C 60 and C 70, were Soxhlet extracted from collected soot with chlorobenzene, by modified procedure yielding 5.8% of the extract. Chlorobenzene fullerenes extract was then separated on an active alumina column, modifying the existing methods, by elution with hexane and xylene/hexanes mixtures in determined ratios and orders. Buckminsterfullerene C 60 was identified in the first purified fraction using EI mass spectrometry, IR and UV/vis methods. The second and the third purified fraction, carbon soot and chlorobenzene soot extract were characterized by IR and UV/vis methods. Identifications of fullerenes in purified and unpurified forms were analyzed and compared.
On clean ideals
Authors: Chen Huanyin , Chen Miaosen
Published: November 2003

We introduce the notion of clean ideal, which is a natural
generalization of clean rings. It is shown that every matrix
ideal over a clean ideal of a ring is clean. Also we prove that
every ideal having stable range one of a regular ring is clean.
These generalize the corresponding results for clean
rings.
Nested symmetric representation of elements of the Suzuki chain groups
Authors: Sayed Mohamed
Published: November 2003

We demonstrate an economic and concise method for representing
the elements of groups involved in the Suzuki chain. For example,
we represent each element of Suz : 2 by a permutation on 14
letters from L3(2) : 2 followed by four words, each of length at
most two, in 14, 36, 100, and 416 involutory symmetric
generators, respectively. Such expressions will have an obvious
advantage over permutations on 1782 provided that it is
reasonably simple to multiply and invert them. We refer to this
as nested symmetric representation of an element of the
group.
Shields‐Harary numbers of graphs with respect to continuous concave cost functions
Authors: Holliday John , Johnson Peter
Published: November 2003

The Shields‐Harary numbers are a class of graph parameters that
measure a certain kind of robustness of a graph, thought of as a
network of fortified reservoirs, with reference to a given cost
function. We prove a result about the Shields‐Harary numbers with
respect to concave continuous cost functions which will simplify
the calculation of these numbers for certain classes of graphs,
including graphs formed by two intersecting cliques, and complete
multipartite graphs.
Parrondo′s paradox
Authors: Berresford Geoffrey C. , Rockett Andrew M.
Published: November 2003

Since coming to the attention of the general news media several
years ago, the paradoxical combination of two losing games into a
winning game by J. M. R. Parrondo has been the subject of
numerous numerical investigations and simulations. This note
provides a clear statement of the nature of the paradox together
with a straightforward analysis and resolution that is accessible
to a wide audience.
On Pierce‐like idempotents and Hopf invariants
Authors: Dula Giora , Hilton Peter
Published: November 2003

Given a set K with cardinality ‖K‖  = n, a wedge
decomposition of a space Y indexed by K, and a cogroup A,
the homotopy group G = [A, Y] is shown, by using Pierce‐like
idempotents, to have a direct sum decomposition indexed by
P(K) − {ϕ} which is strictly functorial if G is abelian.
Given a class ρ : X → Y, there is a Hopf invariant
HIρ on [A, Y] which extends Hopf′s definition when ρ is a comultiplication. Then HI = HIρ is a functorial sum of HIL over L ⊂ K, ‖L‖  ≥ 2. Each HIL is a
functorial composition of four functors, the first depending only
on An+1, the second only on d, the third only on ρ,
and the fourth only on Yn. There is a connection here with
Selick and Walker′s work, and with the Hilton matrix calculus, as
described by Bokor (1991).
Biallelic transcriptional activation of oncogenic transcription factors in T-cell acute lymphoblastic leukemia
Authors: Ferrando Adolfo A. , Herblot Sabine , Palomero Teresa , Hansen Mark , Hoang Trang , Fox Edward A. , Look A. Thomas
Published: November 2003

Aberrant expression of transcription factor oncogenes such as HOX11, HOX11L2, TAL1/SCL, LYL1, LMO1, and LMO2 can be detected in lymphoblasts from up to 80% of patients with acute T-cell lymphoblastic leukemia (T-ALL). Transcriptional activation of these oncogenes in leukemic cells typically results from chromosomal rearrangements that place them next to highly active cis-acting transcriptional regulatory elements. However, biallelic activation of TAL1 in some T-ALL cases has been previously proposed. We have used allele-specific mRNA analysis to show that trans-acting mechanisms leading to biallelic overexpression of TAL1 are involved in 10 (42%) of 24 TAL1+ informative T-ALL cases, 2 (17%) of 12 HOX11+ informative cases, and 7 (64%) of 11 LMO2+ informative cases. We propose that aberrant expression of oncogenic transcription factors in a significant fraction of T-ALLs may result from loss of the upstream transcriptional mechanisms that normally down-regulate the expression of these oncogenes during T-cell development.
Mechanisms of homing in the fiddler crabUca rapax2. Information sources and frame of reference for a path integration system
Authors: Layne John E. , Barnes W. Jon P. , Duncan Lindsey M. J.
Published: November 2003

Fiddler crabs Uca rapax are central-place foragers, making feeding excursions of up to several meters from their burrows. This study investigates the sources of directional and distance information used by these crabs when returning to their burrows. We tested the spatial frame of reference(egocentric or exocentric), and the source of spatial information (idiothetic or allothetic) used during homing. We also tested which components of their locomotion they integrated (only voluntary, or voluntary plus reflexive).

Fiddler crabs in their natural mudflat habitat were passively rotated during normal foraging behavior using experimenter-controlled disks, before they returned home. Crabs resisted passive rotations on the disk by counter-rotating when the disk turned, which was a compensatory response to unintended movement. Crabs were usually situated eccentrically on the disk,and therefore were also subjected to a translation when the disk rotated. No crab actively compensated for this translation. Crabs that fully compensated for disk rotation made no directional homing error. Crabs that did not fully compensate homed in a direction that reflected their new body orientation. In other words, if we succeeded in reorienting a crab (i.e. it undercompensated for disk rotation), its homing error was equal to the angle by which it had been reoriented, regardless of the magnitude of the optomotor compensation.

Computer-modelled crabs, each equipped with a path integrator utilizing different combinations of external (allothetic) and path-related (idiothetic)input, traversed the digitized paths of the real crabs. The home vector computed by the model crab was then compared to the homing direction observed in the real crab. The model home vector that most closely matched that of the real crab was taken to comprise the path integration mechanism employed by fiddler crabs. The model that best matched the real crab gained direction and distance idiothetically (from internal sources such as proprioceptors), and integrated only voluntary locomotory information.

Crabs were also made to run home across a patch of wet acetate, on which they slipped and were thus forced to take more steps on the homeward path than theoretically required by the home vector. Crabs whose running velocity across the patch was unusually low also stopped short of their burrow before finding it. Crabs whose running velocity was not impeded by the patch did not stop short, but ran straight to the burrow entrance, as did control crabs that ran home with no slippery patch. We interpret this to mean that the velocity of some crabs was impeded because of slipping, and these therefore stopped short of their burrow after having run out their homing vector. This is positive evidence in support of the hypothesis that path integration is mediated either by leg proprioceptors or by efferent commands, but our data do not allow us to distinguish between these two possibilities.
Auto-spermatophore extrusion in male crickets
Authors: Kumashiro Mikihiko , Tsuji Yohei , Sakai Masaki
Published: November 2003

The reproductive cycle of the male cricket consists of the mating stage and the sexually refractory stage. The latter is further divided into the first refractory stage (RS1) from spermatophore extrusion in copulation to spermatophore preparation after copulation, and the second refractory stage(RS2) from spermatophore preparation to recommencement of a calling song. RS2 is time-fixed and unaffected by the female or by stress, hence RS2 is assumed to be controlled by the reproductive timer. Previously, we suggested that the timer is located in the terminal abdominal ganglion (TAG), because functional inactivation of the TAG by local cooling lengthened RS2 in proportion to cooling time. To obtain further evidence of timer localization and to examine the operation of the timer in dissected animals, we investigated the characteristics of auto-spermatophore extrusion, a phenomenon in which males eject the mature spermatophore themselves without any prior courtship. The occurrence of auto-spermatophore extrusion was 100% in dissected males with the TAG separated, compared to 1.7% in intact males. The time interval (SPaSE)between spermatophore preparation and auto-spermatophore extrusion was comparable to RS2 measured by the calling song. Spike recording from a genital motor neurone in the separated TAG indicated that burst discharge associated with auto-spermatophore extrusion occurred with a SPaSE comparable to RS2. Other efferent neurones, some of which were identified as dorsal unpaired median (DUM) neurones, showed a time-dependent spike frequency increase during SPaSE. These results strengthen our previous conclusion that the reproductive timer is located within the TAG, and demonstrate that the timer functions normally even when the TAG is separated from the central nervous system.
Heterotrophy on ultraplankton communities is an important source of nitrogen for a sponge–rhodophyte symbiosis
Authors: Pile Adele J. , Grant Adrienne , Hinde Rosalind , Borowitzka Michael A.
Published: November 2003

Grazing on ultraplankton by the sponge partner of an invertebrate/algal symbiotic association can provide enough particulate organic nitrogen to support the nitrogen needs of both partners. The previously unknown natural diet of the sponge in the Haliclona–Ceratodictyon association consists of bacteria and protozoans, which are rich sources of nitrogen. Retention of ultraplankton varied with season and time of day. During the winter there was an order of magnitude more nitrogen taken up than in summer. Time of day during each season also affected the amount of ultraplankton retained. In summer retention was higher at night whereas the opposite was true during winter. Overall, the Haliclona–Ceratodictyonassociation is able to meet its metabolic nitrogen demands through grazing on the naturally occurring water column community.
Controlling muscle mitochondrial content
Authors: Moyes Christopher D.
Published: November 2003

Mitochondrial content, a chief determinant of aerobic capacity, varies widely among muscle types and species. Mitochondrial enzyme levels in vertebrate skeletal muscles vary more than 100-fold, from fish white muscle to bird flight muscles. Recent studies have shed light on the transcriptional regulators that control mitochondrial gene expression in muscle fiber differentiation and development, and in the context of pathological conditions such as neuromuscular disease and obesity. While the transcriptional co-activator PGC-1α (peroxisome proliferator-activated receptor gamma co-activator 1) has emerged as a master controller of mitochondrial gene expression, it is important to consider other mechanisms by which coordinated changes in mitochondrial content could arise. These studies,largely using biomedical models, provide important information for comparative biologists interested in the mechanistic basis of inter-species variation in muscle aerobic capacity.
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

Aging 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

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).
Price-Based Global Market Segmentation for Services
Authors: Bolton Ruth N. , Myers Matthew B.
Published: November 2003

In business-to-business marketing, managers are often tasked with developing effective global pricing strategies for customers characterized by different cultures and different utilities for product attributes. The challenges of formulating international pricing schedules are especially evident in global markets for service offerings, where intensive customer contact, extensive customization requirements, and reliance on extrinsic cues for service quality make pricing particularly problematic. The purpose of this article is to develop and test a model of the antecedents of business customers’ price elasticities of demand for services in an international setting. The article begins with a synthesis of the services, pricing, and global marketing literature streams and then identifies factors that account for differences in business customers’ price elasticities for service offerings across customers in Asia Pacific, Europe, and North America. The findings indicate that price elasticities depend on service quality, service type, and level of service support and that horizontal segments do exist, which provides support for pricing strategies transcending national borders. The article concludes with a discussion of the managerial implications of these results for effective segmentation of global markets for services.
Teaching Old Brands New Tricks: Retro Branding and the Revival of Brand Meaning
Authors: Brown Stephen , Kozinets Robert V. , Sherry John F.
Published: November 2003

Retro brands are relaunched historical brands with updated features. The authors conduct a “netnographic” analysis of two prominent retro brands, the Volkswagen New Beetle and Star Wars: Episode I—The Phantom Menace, that reveals the importance of Allegory (brand story), Aura (brand essence), Arcadia (idealized community), and Antinomy (brand paradox). Retro brand meanings are predicated on a utopian communal element and an enlivening paradoxical essence. Retro brand management involves an uneasy, cocreative, and occasionally clamorous alliance between producers and consumers.
Optical Fiber Communications
Authors: Keiser Gerd
Published: November 2003

Optical 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

This 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

The 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

Turbo 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

—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.
Optical Modulators—Lithium Niobate
Authors: Madabhushi Rangaraj
Published: November 2003

The modulation schemes, general principles of operation, design considerations, device characteristics, fabrication technology and reliability aspects of the Lithium Niobate modulators are discussed. on and reliability of the Lithium Niobate optical modulators.
Peak‐to‐Average Power Ratio of Orthogonal Frequency‐Division Multiplexing
Authors: Tellambura Chintha , Parker Matthew G.
Published: November 2003

OFDM 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

This 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

In 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

The 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

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

In 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

Ethernet 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

In 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

This 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

The 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

In 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

A 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

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

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

This 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

This 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.
Liquid‐Phase Separation with the Rotational Particle Separator
Authors: van Kemenade E. , Mondt E. , Hendriks T. , Verbeek P.
Published: November 2003

Recently, the rotational particle separator (RPS) was introduced as a new technique for separating solid and/or liquid particles of 0.1 μm and larger from gases. In this patented technique the principles of centrifugation are exploited to enhance separation of small‐sized phases and particulate matter of density different from the carrier fluid. Practical designs of the RPS available in the market include equipment for purifying gases of industrial processes and portable air cleaners for domestic appliances. New developments are made in the area of the offshore industry. It concerns the separation of oil droplets from water and the separation of condensate, oil, and sand from natural gas. A particular feature of both designs is that the filter element is freely mounted in bearings and rotates, without the need of a motor, by introducing a swirl in the fluid flowing towards the filter element. The design is particularly suited for operation under high pressures as the rotating filter element is fully contained within a cylindrical pipe. The shaft does not pin through the external wall, so no sealing is required. Based on known RPS design principles and fluid flow relations an oil‐water separator is designed and tested.
Where is the Anion Extraction Going?
Authors: Gloe K. , Stephan H. , Grotjahn M.
Published: November 2003

Reactive extraction processes represent efficient and smart technologies for separation and concentration of metal ions in solution, which are frequently used in industry. Despite the importance of anions in biology, medicine, environment and industry, practical examples of anion extraction are relatively limited compared to metal ion separation. Anion extraction processes are mainly based on the nonspecific ion pair formation with hydrophobic ammonium cations. In this case the phase transfer of anions is dominated by their lipophilicity. The reasons for this situation are closely connected with the specific features of anions in contrast to cations. Novel approaches for specific binding and selective transport of anionic components are based both on the better understanding of the biological role of anions and on the possibilities of supramolecular chemistry to create receptor architectures with complementary binding modes for anions. In the given review the authors discuss present research tendencies and application possibilities of new extractant types for separation and concentration of anionic species in solution.
Poly(vinyl alcohol) Ultrafiltration Membranes: Synthesis, Characterization, the Use for Enzyme Immobilization
Authors: Djennad M. , Benachour D. , Berger H. , Schomäcker R.
Published: November 2003

An enzymatic hydrolysis in a symmetric membrane, combining reaction and separation, has been studied. PVA hydrogel was chosen because of its hydrophilicity expecting to minimize membrane fouling and concentration polarization. The membrane pores containing covalently bound enzymes serve as catalyst support. The membrane immobilization of the enzyme and the filtration mode of operating the process were chosen in order to avoid product inhibition of the enzyme. The properties of cross‐linked PVA hydrogel were investigated. The conversion of the hydrolysis of p‐nitrophenyllaurate with two different loadings of Cr lipase was evaluated. The conversion of the reaction decreased with both increasing substrate flux and initial concentration. The kinetic parameters were obtained. Compared to the free lipase, the Km of the membrane bonded enzyme was lower and its Rmax approximately the same.
Biosorption Processes for Natural and Waste Water Treatment – Part II: Experimental Studies and Theoretical Model of a Biosorption Fixed Bed
Authors: Pidlisnyuk V.V. , Marutovsky R.M. , Radeke K.‐H. , Klimenko N.A.
Published: November 2003

A model has been developed for fixed‐bed biosorption performance, i.e. combined action of adsorption of organic water contaminants and their biological destruction in a column. The model contains an adsorption isotherm of the Freundlich type, adsorption kinetics by an overall film mass transfer (Glueckauf equation), maximum bacterial growth,and biological aerobic destruction (Monod model) of the organics by exoenzymes. Bacteria can not penetrate into the pores of the adsorbent. The model was tested using the system aqueous solution of aniline/Pseudomonas putida/Polysorb 40/100. Breakthrough curves in shorter columns have been measured and a velocity‐dependent steady‐state exit concentration was achieved. These curves could be simulated with sufficient accuracy on the basis of isotherm data, mass transfer coefficients and values of biological growth and destruction activity estimated from independent measurements.
From London to Liverpool: Evidence for a Limehouse–Reid porcelain connection based on the analysis of sherds from the Brownlow Hill (ca. 1755–1767) factory site
Authors: Owen J. Victor , Hillis Maurice
Published: November 2003

The diversity of Brownlow Hill porcelains of the Wm Reid & Co. era is due to the remarkably wide range in the composition of their pastes and glazes and inferred firing conditions relative to the initial vitrification temperature. Sixteen of 21 analyzed sherds from the factory site are bone‐ash wares that display large variations in their bulk chemical composition. The remaining samples have silicious‐aluminous (akin to “stone china” sensu Richard Pococke in 1750) and silicious‐aluminous‐calcic (“S‐A‐C”) compositions that resemble Limehouse (London) and Pomona (Staffordshire) porcelains produced during the 1740s. The mineralogy of the Brownlow Hill S‐A‐C sherds suggests firing at a relatively high temperature (Tmax approaching 1400°C, based on relations on the SiO2‐Al2O3‐CaO phase diagram), thereby obscuring the identity of some of the ingredients (e.g., the source of CaO) used in their manufacture. Limehouse and Brownlow Hill may have been linked through the activities of William Ball, who is mentioned in connection with both factories, or indirectly via former Limehouse staff later employed at the Pomona factory, located not far from a Wm Reid & Co. branch factory in Shelton, Stoke‐on‐Trent. In terms of a time line, knowledge of these pastes appears to have spread first from London to Staffordshire, and then to Liverpool. © 2003 Wiley Periodicals, Inc.
Use of versant™ TMA and bDNA 3.0 assays to detect and quantify hepatitis C virus in semen
Authors: Pekler Vyacheslav A. , Robbins Wendie A. , Nyamathi Adeline , Yashina Tatyana L. , Leak Barbara , Robins Terry A.
Published: November 2003

Previous findings of hepatitis C virus (HCV) in human semen have been inconsistent. This study attempted to elucidate the presence of HCV in semen from 80 HCV RNA blood plasma positive homeless men using two novel non‐PCR based techniques. Semen was frozen immediately upon ejaculation in order to preserve virus quantity. This study demonstrated that 36% of the study population had HCV in semen. Bayer's Versant™ HCV RNA Qualitative Assay (Bayer Diagnostics, Emeryville, CA) based on transcription mediated amplification (TMA) assay detected 29 positive semen samples and Versant™ HCV RNA 3.0 Assay (bDNA) (Bayer Diagnostics, Emeryville, CA) detected only six. This demonstrated that TMA was more sensitive than the bDNA in detecting HCV in semen (P<0.002). HCV blood plasma viral load was positively correlated with the presence of HCV in semen (Spearman's Rho=0.40, P<0.0002), while the presence of leukocytes in semen was not (Spearman's Rho=0.19, P<0.12). This supports the hypothesis that HCV is “leaked out” from the peripheral circulation into semen. Three semen samples had a viral load of >5,000 IU/mL. The presence of a high viral load in semen in certain men suggests that sexual transmission of the virus is possible. Laboratory capability to accurately detect HCV positive semen is an important step in establishing the risk of sexual transmission and in identifying strategies for protecting uninfected partners. J. Clin. Lab. Anal. 17:264–270, 2003. © 2003 Wiley‐Liss, Inc.