bluuebunny/crossref_metadata_2025 huggingface dataset:
National culture, trust, and perceptions about ethical behavior in intra‐ and cross‐cultural negotiations: An analysis of NAFTA countries
Authors: Elahee Mohammad N. , Kirby Susan L. , Nasif Ercan
Published: November 2002

This study investigates the role of national culture in the formation of the trust that people are likely to
extend to exchange partners in business negotiations and, consequently, how the level of such trust influences the
likelihood of using certain questionable tactics in intra‐ and cross‐cultural negotiations. Based on
survey data collected from businesspeople from Canada, Mexico, and the United States, this article shows that trust
is culturally embedded and has a negative relationship with the likelihood of using certain questionable negotiation
tactics. The study found that Mexican negotiators are less likely to use questionable negotiation tactics in
intracultural negotiations as compared to cross‐cultural negotiations. On the other hand,the intended
negotiation behaviors of Canadian and U.S. negotiators were not found to vary significantly across intra‐ and
cross‐cultural negotiations. The findings of the study underscore the importance of building relationship
with exchange partners, especially when such exchange partners come from countries that represent collectivistic,
high‐context, strong uncertainty‐avoidance,and large power‐distance cultures. © 2002 Wiley
Periodicals, Inc.
Negotiating alliances in emerging markets—Do partners' contributions matter?
Authors: De Mattos Claudio , Sanderson Stuart , Ghauri Pervez
Published: November 2002

This article explores a “tool” that may be used for the informal phase of negotiations of
alliances in emerging markets. Four different partner perspectives of the partners of an alliance are analyzed:
how the foreign investor views his own contributions to the venture, how the foreign investor views the local
partner's contributions, how the local partner views his own contributions, and how the local partner
views the contributions of the proposed foreign investor. Three categories of differences in perception are
identified. These four perspectives and three categories are discussed using the appropriate research findings
from relevant literature. The article discusses the implications for business negotiations of the identified
perceptual conflicts for international business practitioners, researchers, and policy makers. © 2002
Wiley Periodicals, Inc.
Cyst‐based toxicity tests XII—Development of a short chronic sediment toxicity test with the ostracod crustaceanHeterocypris incongruens: Selection of test parameters
Authors: Chial Belgis , Persoone Guido
Published: November 2002

Experiments were carried out with neonates of the freshwater ostracodHeterocypris incongruenshatched from cysts in order to develop a new culture/maintenance‐free solid‐phase microbiotest for the toxicity assessment of contaminated sediments. Based on preliminary investigations, a number of test parameters were investigated for a short‐chronic assay: hatching time, size of the cups of the multiwell test plates, feeding of the test organisms prior to the test, amount of supplemental algal food, volume of sediment, and duration of the test. On the basis of the findings, a test protocol was formulated for a 6‐day assay in 12‐cup multiwell plates with 10 organisms per cup and 3 replicates. The test organisms were collected 52 h after the start of the incubation of the cysts in standard freshwater at 25°C under continuous illumination after a 4‐h prefeeding with 1.3 mg/mLSpirulina.The test biota in the cups were exposed to 300 μL of test sediment in 2 mL of standard freshwater with 3 × 107live algal cells (Raphidocelis subcapitata) as food supplement. Calibrated sand was used as a reference sediment. Mortality and growth of the ostracods were determined after 6 days' incubation at 25°C in darkness. The selected test parameters for the new microbiotest were found adequate for toxicity determination of natural sediments compared with the 10‐day contact test with the amphipodHyalella azteca. © 2002 Wiley Periodicals, Inc. Environ Toxicol 17: 520–527, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/tox.10085
Cyst‐based toxicity tests XIII—Development of a short chronic sediment toxicity test with the ostracod crustacean Heterocypris incongruens: Methodology and precision
Authors: Chial Belgis , Persoone Guido
Published: November 2002

Experiments were carried out with neonates of the freshwater ostracod Heterocypris incongruens to verify and complete previous choices of test parameters for a new culture/maintenance‐free solid‐phase microbiotest for freshwater sediments. From trials with increasing volumes of reference sediment, it was concluded that 300 μL was the most appropriate amount of substrate to be put in 12‐cup multiwell plates with 2 mL of standard freshwater. Tests in 3–9 replicates eventually showed that six parallels were needed to have good assay precision (repeatability). Application of the final test protocol to oil‐contaminated sediments from the St. Lawrence River in Canada revealed that the 6‐day chronic ostracod microbiotest had less variation in repeated tests than did the 10‐day contact assay with Hyalella azteca and hence can be considered more precise. Based on the 95% confidence intervals for mortality and growth of the ostracods in the controls (reference sediment) of the 56 tests carried out for the Canadian project, a validity threshold of 20% for mortality was eventually selected, in analogy with the acceptability limits applied in many chronic bioassays. A minimum length of 600 μm in the control sediment after 6 days' exposure was also taken as the threshold for good health of the test organisms and for reliable test conditions. The new microbiotest has been tailored in a handy and user‐friendly new toxkit, the Ostracodtoxkit, which is particularly suited for cost‐effective routine monitoring. © 2002 Wiley Periodicals, Inc. Environ Toxicol 17: 528–532, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/tox.10086
Cyst‐based toxicity tests XIV—Application of the ostracod solid‐phase microbiotest for toxicity monitoring of river sediments in Flanders (Belgium)
Authors: Chial Belgis , Persoone Guido
Published: November 2002

In view of the need for rapid and low‐cost solid‐phase assays for contaminated sediments, a new 6‐day “culture/maintenance‐free” microbiotest has been developed with the freshwater ostracod crustacean Heterocypris incongruens at the Laboratory for Biological Research in Aquatic Pollution at the Ghent University in Belgium. The sensitivity of the Ostracodtoxkit F™ has been compared with that of the 10‐day sediment contact test with the amphipod crustacean Hyalella azteca and the two pore water assays (on the anostracan crustacean Thamnocephalus platyurus and the microalgae Raphidocelis subcapitata) selected by the Flemish Environmental Agency for initial hazard assessment of contaminated sediments. The exercise was performed on 26 sediments collected at random from various rivers of the Flemish hydrographic basin in Belgium. The toxicity data ranged from nontoxic to highly toxic for the solid‐phase assays and showed that the mortality of the two test biota varied from “nearly identical” to “substantially different,” depending on the sediment. The correlation coefficient for the data pairs was weakly positive (r = 0.60), mainly because of 5 samples for which a low mortality had been noted with the ostracod versus a much higher mortality for the amphipod. However, for 4 out of the 5 samples of concern, a substantial growth inhibition was recorded for H. incongruens, showing that this assay eventually performed as did the amphipod test in detecting the toxic character of the sediments. The comparison of toxicity data of the two solid‐phase assays with those of the two pore water tests again confirmed that both types of bioassay provided complementary (nonredundant) information. On the basis of its various advantages (independence of stock culturing/maintenance, user‐friendliness, precision, and time and cost savings) the new ostracod microbiotest appears to be a promising tool for routine toxicity assessment of contaminated sediments. © 2002 Wiley Periodicals, Inc. Environ Toxicol 17: 533–537, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/tox.10087
Effects of cyanobacterial biomass and purified microcystins on malformations inXenopus laevis: Teratogenesis assay (FETAX)
Authors: Dvořáková Dagmar , Dvořáková Kateřina , Bláha Luděk , Maršálek Blahoslav , Knotková Zora
Published: November 2002

Xenopus laevis(African clawed frog) embryos in a 96‐h teratogenesis assay (FETAX) were exposed to 0–250 μg/L and 500 μg/L of purified microcystin‐LR (MCYST‐LR) for the estimation of lethality, as well as to equivalent concentrations of biomass containing MCYST‐LR (natural water bloom dominated byMicrocystis aeruginosa)and biomass without MCYST‐LR (bloom dominated byMicrocystis wesenbergii). The highest tested concentrations of purified MCYST‐LR caused up to 30% lethality after a 96‐h exposure, corresponding to a LC25of 380 μg/L. Cyanobacterial biomass containing MCYST‐LR caused significant lethality up to 50% at the highest tested concentrations (300 mg/L, i.e., 250 μg/L of MCYST‐LR). The estimated 96‐h LC25values varied from 125 mg/L (biomass containing MCYST‐LR) up to 232 mg/L (biomass without MCYST‐LR). A statistically significant increase in the number of malformed embryos was observed after exposure to cyanobacterial samples. Purified MCYST‐LR at and above 25 μg/L significantly increased the number of malformations, with 53% of surviving embryos malformed in the highest tested concentration, 250 μg/L (EC25= 27 μg/L). Exposure to the highest concentration of MCYST‐LR containing biomass resulted in more than 60% of the embryos being malformed and an EC25of 52 mg/L (i.e., 43 μg of MCYST‐LR/L). Cyanobacterial biomass with no natural microcystin also induced substantial malformations—about 50% aberrant embryos at the highest concentration, 300 mg/L (EC25= 75 mg/L). External additions of purified MCYST‐LR to the biomass that was originally without microcystins resulted in a slight additional increase in the rate of malformations (80% at the highest concentration, 300 mg of biomass plus 250 μg of MCYST‐LR per liter). A comparison of lethality and effects on malformations (teratogenic index,TI= LC25/EC25) showed that all samples had significant teratogenic potential in the FETAX assay (TIMCYST‐LR= 14;TIfor biomass with and without microcystin ranged between 2.4 and 3.1, respectively). We conclude that cyanobacterial water blooms can significantly alter the normal development of amphibian embryos. © 2002 Wiley Periodicals, Inc. Environ Toxicol 17: 547–555, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/tox.10088
Polycyclic aromatic hydrocarbon contamination and LUMIStox® solvent extract toxicity of marine sediments in the North Aegean Sea, Greece
Authors: Papadopoulou Despina , Samara Constantini
Published: November 2002

Organic extracts of surface marine sediment collected from six sites within the bay of Kavala (north Aegean Sea, Greece) were used for determining priority pollutant polycyclic aromatic hydrocarbons (PAHs) and doing toxicity testing. PAH analyses and LUMIStox® acute toxicity measurements were conducted in two sediment grain‐size fractions: silt/clay (< 63 μm) and sand (63–2000 μm). Sixteen PAH concentrations were found at low‐ to moderate levels, ranging from 44 to 166 ng/g dry weight in the fine fraction and from 45 to 148 ng/g dry weight in the coarse fraction. Molecular indices revealed that PAHs in the bay sediment originate mainly from pyrolytic sources, but some petroleum influence was also evident. A comparison of sedimentary PAH levels with sediment quality guidelines (SQGs) indicated an absence of acutely toxic concentrations. However, all sediment extracts were found to be toxic with the LUMIStox® acute toxicity test, with 15‐min EC50s in the ranges of 1.0–4.0 and 1.1–4.5 mg of dry sediment/mL for the fine and the coarse fractions, respectively. No significant correlations between EC50s and concentrations of individual or total PAHs was found, suggesting that chemical analysis of PAHs alone cannot be considered a reliable indicator of sediment toxicity. © 2002 Wiley Periodicals, Inc. Environ Toxicol 17: 556–566, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/tox.10089
Use of RNA arbitrarily primed PCR to identify genomic alterations in the digestive gland of the freshwater bivalve Unio tumidus at a contaminated site
Authors: Rodius F. , Hammer C. , Vasseur P.
Published: November 2002

The technique of RNA arbitrarily primed polymerase chain reaction (RAP‐PCR) was developed to detect DNA damage and variations in gene expression in response to exposure to toxic compounds. This approach was tested on the freshwater bivalve Unio tumidus to explore the ability of RAP‐PCR to detect effects induced by river sediment contaminated with polycyclic aromatic hydrocarbons (PAHs), polychlorobiphenyls (PCBs), and metals. In a first step the primer concentration was optimized to obtain reproducible amplifications of both high‐ and low‐molecular‐weight products. Optimized conditions allowed us to detect variations corresponding to the loss of PCR products in some animals exposed at the contaminated site compared with the control. Our results for the RAP‐PCR approach performed on separate animals in field studies showed that interindividual variations could correspond to DNA damage and/or variations in gene expression. © 2002 Wiley Periodicals, Inc. Environ Toxicol 17: 538–546, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/tox.10090
Comparative toxicity of chlorothalonil and chlorpyrifos: Ceriodaphnia dubia and Pimephales promelas
Authors: Sherrard R. M. , Murray‐Gulde C. L. , Rodgers Jr. J. H. , Shah Y. T.
Published: November 2002

This study was done to characterize responses of Ceriodaphnia dubia Richard and Pimephales promelas Rafinesque exposed to aqueous solutions of chlorothalonil (tetrachloroisophthalonitrile) and chlorpyrifos (O,O‐diethyl O‐3,5,6‐trichloro‐2‐pyridyl phosphorothioate). Chlorothalonil (a fungicide) and chlorpyrifos (an insecticide) are intensely used in agricultural, silvicultural, and urban settings. These pesticides may enter aquatic systems through several pathways including rainfall runoff. C. dubia and P. promelas have been used to monitor surface waters and discern the effects of pesticides that contaminate those waters. Modified static renewal exposures (7 or 10 days) with individual solutions of chlorothalonil and chlorpyrifos were used to obtain mortality data for C. dubia and P. promelas, from which potency curves were derived, as well as sublethal effects data (reproduction or growth). In these experiments P. promelas was more sensitive to chlorothalonil, and C. dubia was more sensitive to chlorpyrifos. Lower and upper thresholds (i.e., LC0 and LC100) for 7‐day P. promelas exposures to chlorothalonil were 14.4 and 30.8 μg/L, respectively, in contrast to the lower and upper threshold values, 103 and 210 μg/L, respectively, for C. dubia. Ten‐day exposures of C. dubia to chlorpyrifos resulted in lower and upper threshold values of 0.05 and 0.09 μg/L, whereas 10‐day exposures of P. promelas to chlorpyrifos yielded threshold values of 26 and 274 μg/L. The results of this study illustrated differences in species' sensitivities to chlorothalonil and chlorpyrifos as well as differences in the duration of the exposure necessary to illustrate effects that might be elicited from pesticide exposures. © 2002 Wiley Periodicals, Inc. Environ Toxicol 17: 503–512, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/tox.10091
PCBs, mercury, and organochlorine concentrations in lake trout, walleye, and whitefish from selected tribal fisheries in the Upper Great Lakes region
Authors: Gerstenberger Shawn L. , Dellinger John A.
Published: November 2002

The purpose of this study was to determine the concentrations of environmental contaminants in the edible portion of fish tissue consumed by Ojibwa residing in the Upper Great Lakes region. Lake trout, whitefish, and walleye were collected from Lake Superior, Lake Huron, Lake Michigan, and selected inland lakes. These fish were harvested by either commercial fishing or spearfishing techniques and analyzed for environmental contaminants. Samples were pooled by species and location of collection and were analyzed as composites. The concentrations of congener‐specific polychlorinated biphenyl (PCB), total mercury, and 17 other organochlorine compounds of the pooled samples were determined using gas chromatographic and atomic absorption techniques. Differences were noted in both the concentration and composition of contaminants depending on the geographic location of collection and the species examined. Lake trout and whitefish contained higher concentrations of organochlorine compounds than did walleye; and samples from Lakes Michigan and Huron had much higher concentrations than did Lake Superior fish. Conversely, mercury was much higher in walleye (580 ppb) when compared with lake trout (117 ppb) and whitefish (10 ppb). Several PCB congeners were commonly found in all fish samples; these included PCBs 138 + 163, 153, 66 + 95, 118, 77 + 110, 180, and 101. Lake trout accumulated the highly chlorinated PCB congeners, whereas walleye and whitefish accumulated certain lower tri‐ and tetrachlorobiphenyl congeners. In conclusion, the fish harvested and consumed by Ojibwa tribal members contained both mercury and organochlorine compounds. The concentrations of contaminants found in fish tissue differed among species and sampling sites. Consequently, it is imperative to sample fish that best represent those being consumed by tribal members and to continue long‐term monitoring of fish from ceded waters. Therefore, risk assessment and risk management strategies need to take into account geographic location of the fish and unique preparation methods and to be directed at the contaminant(s) of concern for given locations. © 2002 Wiley Periodicals, Inc. Environ Toxicol 17: 513–519, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/tox.10092
Sensitivity of juvenile Macomona liliana (bivalvia) to UV‐photoactivated fluoranthene toxicity
Authors: Ahrens Michael J. , Nieuwenhuis Ronald , Hickey Christopher W.
Published: November 2002

This study assessed the sensitivity of Macomona liliana (bivalvia, tellinacea) to UV‐photoactivated fluoranthene toxicity. Juvenile clams (0.5–2.0 mm) were exposed to a range of aqueous fluoranthene concentrations (5–500 μg/L) for 96 h, after which the clams' ability to rebury in control sediment was determined. Survivors of these fluoranthene‐only toxicity tests were then exposed in clean seawater to UV radiation from a solar radiation–simulating light source for 1 h. The differences between EC50 values before and after UV exposure provided a measure of phototoxicity of the bioaccumulated fluoranthene. Fluoranthene tissue burdens corresponding to the EC50 values were determined by exposing a second batch of clams to 14C‐radiolabeled fluoranthene. A third experiment quantified the kinetics of fluoranthene uptake and elimination in water‐only exposures. Fluoranthene phototoxicity was found to depend on the dose of fluoranthene and the duration of UV exposure. Exposure of animals to 1 h of UV radiation resulted fluoranthene toxicity that was 3 times higher (EC50 = 46 μg/L) than that of those with no UV exposure (EC50 = 153 μg/L). The corresponding critical body burden (i.e., fluoranthene tissue concentration at which 50% of the clams failed to rebury) was 6 ng/clam (or 700 μg/g dry weight [dw]) and 21 ng/clam (or 2300 μg/g dw) for UV‐exposed and UV‐unexposed animals, respectively. First‐order uptake and elimination coefficients, determined in the kinetics experiment, were 0.825 Lg−1 h−1 and 0.059 h−1, respectively, indicating rapid uptake and a short fluoranthene tissue half‐life of approximately 12 h for M. liliana. Compared with other bivalve species of similar size, M. liliana appeared to be more than 1 order of magnitude less sensitive to UV‐activated fluoranthene toxicity, although these differences may be a result in part of differences in the UV exposure regime. Nonetheless, the majority of M. liliana exposed to a fluoranthene concentration of 50 μg/L displayed evidence of UV‐photoactivated toxicity within 30–60 min of irradiation, and prolonging UV exposure more than 2 h killed all clams. These results demonstrate that even short UV exposures, as perhaps encountered during normal feeding or byssus‐drifting behavior, may significantly increase toxicity to juvenile M. liliana possessing elevated fluoranthene tissue concentrations. © 2002 Wiley Periodicals, Inc. Environ Toxicol 17: 567–577 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/tox.10093
A blind coherent spatiotemporal processor of orthogonal Walsh‐modulated CDMA signals
Authors: Affes Sofiène , Mermelstein Paul
Published: November 2002

A more efficient detection of orthogonal Walsh‐modulated Code Division Multiple Access (CDMA) signals is required not only for better exploitation of current IS‐95 CDMA systems but also for future cdma2000 3G networks. Integration of adaptive antennas at the base station has been recognized as one key lever to increasing capacity and spectrum efficiency. Prospective array‐receiver solutions such as the 2‐D‐RAKE improve performance; however, in the absence of a pilot signal, they have to implement noncoherent detection. In this work, we propose a space‐time processor that achieves coherent detection of orthogonal Walsh‐modulated CDMA signals without a pilot. We assess its performance in spatially correlated Rayleigh‐fading. Simulation results for voice links of 9.6 Kbps indicate that up to an antenna‐correlation factor of 0.8, the proposed receiver outperforms the conventional 2‐D‐RAKE's capacity by 90% in nonselective fading. This gain shrinks fast at higher correlation factors. In selective fading, however, it maintains about a 130% gain in capacity over the entire correlation range. For data links of 153.6 Kbps, this performance advantage increases up to 180–200%. With high‐speed mobiles, however, it vanishes quickly at correlation factors beyond 0.5. Overall, the capacity gains of the proposed spatiotemporal receiver structure increase with reduced relative Doppler (Doppler‐frequency/symbol‐rate ratio). This may arise from increased spatiotemporal diversity, higher transmission rates, and/or slower mobility. Copyright © 2002 John Wiley & Sons, Ltd.
Models for MIMO propagation channels: a review
Authors: Yu Kai , Ottersten Björn
Published: November 2002

This paper reviews recently published results on multiple input multiple output (MIMO) channel modeling. Both narrowband and wideband models are considered. We distinguish between two main approaches to MIMO channel modeling, that is, physically based and nonphysically based modeling. The nonphysical models primarily rely on the statistical characteristics of the MIMO channels obtained from the measured data, while the physical models describe the MIMO channel (or its distribution)viasome physical parameters. We briefly review different MIMO channel models and discuss their relationships. Some interesting aspects will be described in more detail and we note areas in which few results are available. Copyright © 2002 John Wiley & Sons, Ltd.
Parallel concatenated turbo multiple antenna coded modulation: principles and performance
Authors: Cui Dongzhe , Haimovich Alexander M. , Chen Hangjun
Published: November 2002

A channel‐coding scheme is introduced that features parallel concatenated recursive systematic codes with multilevel modulation and multiple transmit/receive antennas. The proposed scheme is a type of turbo space–time codes and is referred to asturbo multiple antenna coded modulation(turbo‐MACM). Turbo‐MACM combines the advantages of powerful turbo codes with the transmit/receive diversity of multiple antenna coded modulation. The scheme utilizes recursive and systematic constituent codes and features full rate and, as demonstrated by simulations, full spatial diversity. An iterative symbol‐by‐symbolmaximum a posteriori(MAP) algorithm operating in the log domain is developed for decoding turbo‐MACM. Simulation results are provided for 4‐PSK and 8‐PSK schemes over the block‐fading channel. It is shown that the scheme provides an advantage of 3 to 5 dB over conventional space–time codes of comparable complexity. Copyright © 2002 John Wiley & Sons, Ltd.
Channel estimation and interference suppression for space–time coded systems in frequency‐selective fading channels
Authors: Li Ling , Li Hongbin , Yao Yu‐Dong
Published: November 2002

It is of great interest to provide high data rate services in wireless communication systems. In order to support such services, it is desirable to extend space‐time (ST) coding, originally proposed for known, frequency‐nonselective fading channels, to unknown, multipath channels. In this paper, we consider the problem of interference suppression for wireless TDMA (time division multiple access) systems equipped with multiple transmit antennas and receive antennas in frequency‐selective fading channels. A novel scheme with space‐time block coding based transmit diversity (STTD) is presented to estimate the multipath channel, coherently demodulate information symbols, and meanwhile suppress radio interference. The proposed scheme is simple to implement and able to mitigate interference of various origins, including intersymbol interference (ISI), cochannel interference (CCI), and others. Numerical examples are presented to illustrate the performance of the proposed estimator and detector in multipath Rayleigh‐fading channels. Copyright © 2002 John Wiley & Sons, Ltd.
A moment generating function (MGF)‐based approach for performance evaluation of space‐time coded communication systems
Authors: Simon Marvin K.
Published: November 2002

A few years back, a generic analysis approach referred to as the MGF method was introduced for the purpose of simplifying the evaluation of the performance of digital communication over fading channels. A particular case of high interest that fell under the umbrella of the methodology was the evaluation of the average error probability performance of systems that employ receive diversity to combat multipath as well as the possible inclusion of error‐correcting coding/decoding for improving power efficiency. In this paper, we extend the methodology to space‐time coded systems. Illustrative examples are explicitly given for space‐time trellis coding. The emphasis of the paper is on the performance analysis tools and their application, as opposed to the design of the space‐time codes themselves. Copyright © 2002 John Wiley & Sons, Ltd.
Space–time receivers for GSM radio interfaces in subway tunnel environments
Authors: González‐López Miguel , Dapena Adriana , Castedo Luis , Lienard Martine , Degauque Pierre , Asarta María J. , Crespo Pedro
Published: November 2002

In this paper, we investigate how to increase the capacity of GSM (Global System for Mobile communications) radio interfaces in subway tunnel environments by means of antenna arrays and Space–Time (ST) receivers. We address the modeling, both theoretically and experimentally, of the multiple‐antenna wireless channels encountered in subway tunnels. We demonstrate that propagation is conveniently modeled by a flat‐fading channel, but there exist strong spatial correlations among channel components that decrease capacity and affect receivers' performance. Different space–time GSM receiving strategies have also been investigated. We first consider ST equalization techniques that only account for the noise and the controlled Intersymbol Interference (ISI) introduced by the modulation format employed in GSM. Then, we analyze the performance of receivers that incorporate ST coding capabilities and show the superior performance of iterative MAP (Maximum a Posteriori) receivers that interchange soft information among the equalizer and the ST decoder. All receivers are evaluated with experimental channels measured in the subway of Paris. Copyright © 2002 John Wiley & Sons, Ltd.
Complex field coded MIMO systems: performance, rate, and trade‐offs
Authors: Ma Xiaoli , Giannakis Georgios B.
Published: November 2002

The quest for reliable high‐rate wireless links motivates fading‐resilient and bandwidth‐efficient communication systems capable of capitalizing on available forms of diversity. This tutorial focuses on linear complex field (LCF) coding—a powerful tool that complements the traditional Galois field (GF) coding, in enabling diversity transmissions over single‐ and multi‐antenna fading channels. Performance and capacity analyses are provided, along with systematic guidelines for constructing LCF encoders, and options available to the designer for selecting LCF decoders. Emphasis is placed on high‐performance and high‐rate designs, and the emerging performance‐rate‐complexity trade‐offs. Copyright © 2002 John Wiley & Sons, Ltd.
Biogenic silica dissolution in the oceans: Reconciling experimental and field‐based dissolution rates
Authors: Van Cappellen Philippe , Dixit Suvasis , van Beusekom Justus
Published: December 2002

On average, 50–60% of diatomaceous opal produced in the euphotic zone redissolves within the upper 100 m of the water column. High specific silica dissolution rates in the surface ocean contrast with order‐of‐magnitude lower values in deep‐sea sediments. The lack of a mechanistic understanding of these large variations in dissolution kinetics is a major source of uncertainty in models of nutrient silicon cycling in the oceans. Here we show that the observed variability in biogenic silica reactivity is consistent with results of experimental dissolution studies. Differences in aluminum content and specific surface area of the diatom skeletons, plus differences in temperature and degree of undersaturation, all contribute to lowering silica dissolution rates in deep‐sea sediments relative to the euphotic zone. When variations in these material and environmental properties are accounted for, the predicted specific opal dissolution rate in average surface ocean water is over 2 orders of magnitude faster than the rate measured in recently deposited biosiliceous oozes of the Southern Ocean. The predicted specific dissolution rate, however, is approximately 5 times higher than the value obtained from global estimates of the depth‐integrated dissolution rate and biogenic silica concentration in the upper water column. This discrepancy likely reflects the inhibitory effect of protective organic coatings on fresh diatom shells in surface waters. The experimental data further imply that aluminum incorporation in the silica matrix, during biomineralization or after death of the organisms, enhances the preservation efficiency of biogenic opal in marine sediments.
Constraints on the bulk composition and root foundering rates of continental arcs: A California arc perspective
Authors: Ducea Mihai N.
Published: December 2002

Garnet pyroxenites are the most common deep lithospheric xenolith assemblages found in Miocene volcanic rocks that erupted through the central part of the Sierra Nevada batholith. Elemental concentrations and isotope ratios are used to argue that the Sierra Nevada granitoids and the pyroxenite xenoliths are the melts and the residues/cumulates, respectively, resulting from partial melting/fractional crystallization at depths exceeding 35–40 km. The estimated major element chemistry of the protolith resembles a basaltic andesite. Effectively, at more than about 40 km depth, batholith residua are eclogite facies rocks. Radiogenic and oxygen isotope ratios measured on pyroxenites document unambiguously the involvement of Precambrian lithosphere and at least 20–30% (mass) of crustal components. The mass of the residual assemblage was significant, one to two times the mass of the granitic batholith. Dense garnet pyroxenites are prone to foundering in the underlying mantle. An average removal rate of 25–40 km3/km Myr is estimated for this Cordilleran‐type arc, although root loss could have taken place at least in part after the cessation of arc magmatism. This rate is matched by the average subcrustal magmatic addition of the arc (∼23–30 km3/km Myr), suggesting that the net crustal growth in this continental arc was close to zero. It is also suggested that in order to develop a convectively removable root, an arc must have a granitoid melt thickness of at least 20–25 km. Residues of thinner arcs should be mostly in the granulite facies; they are not gravitationally unstable with respect to the underlying mantle.
Paleomagnetism of Upper Vendian sediments from the Winter Coast, White Sea region, Russia: Implications for the paleogeography of Baltica during Neoproterozoic times
Authors: Popov Viktor , Iosifidi Alexander , Khramov Alexei , Tait Jennifer , Bachtadse Valerian
Published: December 2002

Paleomagnetic results from an Upper Vendian sedimentary sequence exposed along the White Sea shoreline, NW Russia are described. These classical exposures have been the subject of intense paleontological investigations due to their well‐preserved Ediacara fauna, but no paleomagnetic results have as yet been published. A total of 337 hand samples and 210 oriented drill cores (35 sites) along three profiles have been collected at the locality (65.5°, 40.0°E) where a 555 ± 3 Ma U–Pb age of comagmatic zircons from volcanic ash layers has been recently obtained. Standard paleomagnetic procedures yield two main natural remanent magnetization (NRM) components: an intermediate‐temperature (150°–350°C), single‐polarity component (D = 121°, I = 72°, n = 232 samples, k = 46.0, α95 = 1.3°, pole position at 40.0°N, 79.0°E, dp = 2.0°, dm = 2.3°) and a high‐temperature (550°–680°C) dual‐polarity component (normal polarity: D = 278°, I = 43°, n = 54 samples, k = 25.2, α95 = 3.9°, reversed polarity: D = 101°, I = −39° n = 40, K = 23.3, α95 = 4.8°, south pole position at 24°S, 132°E, dp = 2.3°, dm = 3.8°). This latter component, termed Z, passes reversal, stratigraphic, and consistency tests and is interpreted to reflect the direction of the Earth's magnetic field during Late Vendian times. These results put Baltica into low northern latitudes (between 10° and 35°) and the resulting pole position requires modification of the most recent Apparent Polar Wander Paths (APWP) for Baltica.
Waveform inversion of oscillatory signatures in long‐period events beneath volcanoes
Authors: Kumagai Hiroyuki , Chouet Bernard A. , Nakano Masaru
Published: December 2002

The source mechanism of long‐period (LP) events is examined using synthetic waveforms generated by the acoustic resonance of a fluid‐filled crack. We perform a series of numerical tests in which the oscillatory signatures of synthetic LP waveforms are used to determine the source time functions of the six moment tensor components from waveform inversions assuming a point source. The results indicate that the moment tensor representation is valid for the odd modes of crack resonance with wavelengths 2L/n, 2W/n, n = 3, 5, 7, …, where L and W are the crack length and width, respectively. For the even modes with wavelengths 2L/n, 2W/n, n = 2, 4, 6, …, a generalized source representation using higher‐order tensors is required, although the efficiency of seismic waves radiated by the even modes is expected to be small. We apply the moment tensor inversion to the oscillatory signatures of an LP event observed at Kusatsu‐Shirane Volcano, central Japan. Our results point to the resonance of a subhorizontal crack located a few hundred meters beneath the summit crater lakes. The present approach may be useful to quantify the source location, geometry, and force system of LP events, and opens the way for moment tensor inversions of tremor.
Problems in data treatment for ionospheric scintillation measurements
Authors: Forte B. , Radicella S. M.
Published: December 2002

Ionospheric scintillation data detrending is reviewed in this paper. The attention is focused on satellite to ground links (mainly GPS) data. The problem of a fixed (“frozen”) cutoff frequency is pointed out. A possible explanation of the presence of “phase without amplitude” scintillations is given as a result of erroneous data detrending.
Contraction integral equation method in three‐dimensional electromagnetic modeling
Authors: Hursán Gábor , Zhdanov Michael S.
Published: December 2002

The integral equation method has been proven to be an efficient tool to model three‐dimensional electromagnetic problems. Owing to the full linear system to be solved, the method has been considered effective only in the case of models consisting of a strongly limited number of cells. However, recent advances in matrix storage and multiplication issues facilitate the modeling of horizontally large structures. Iterative methods are the most feasible techniques for obtaining accurate solutions for such problems. In this paper we demonstrate that the convergence of iterative methods can be improved significantly, if the original integral equation is replaced by an equation based on the modified Green's operator with the norm less or equal to one. That is why we call this technique the Contraction Integral Equation (CIE) method. We demonstrate that application of the modified Green's operator can be treated as a preconditioning of the original problem. We have performed a comparative study of the convergence of different iterative solvers applied to the original and contraction integral equations. The results show that the most effective solvers are the BIGGSTAB, QMRCGSTAB, and CGMRES algorithms, equipped with preconditioning based on the CIE method.
Optimal water management and conflict resolution: The Middle East Water Project
Authors: Fisher Franklin M. , Arlosoroff Shaul , Eckstein Zvi , Haddadin Munther , Hamati Salem G. , Huber‐Lee Annette , Jarrar Ammar , Jayyousi Anan , Shamir Uri , Wesseling Hans
Published: December 2002

In many situations, actual water markets will not allocate water resources optimally, largely because of the perceived social value of water. It is possible, however, to build optimizing models which, taking account of demand as well as supply considerations, can substitute for actual markets. Such models can assist the formation of water policies, taking into account user‐supplied values and constraints. They provide powerful tools for the system‐wide cost‐benefit analysis of infrastructure; this is illustrated by an analysis of the need for desalination in Israel and the cost and benefits of adding a conveyance line. Further, the use of such models can facilitate cooperation in water, yielding gains that can be considerably greater than the value of the disputed water itself. This can turn what appear to be zero‐sum games into win‐win situations. The Middle East Water Project has built such a model for the Israeli‐Jordanian‐Palestinian region. We find that the value of the water in dispute in the region is very small and the possible gains from cooperation are relatively large. Analysis of the scarcity value of water is a crucial feature.
Cluster observations of fast magnetosonic waves in the terrestrial foreshock
Authors: Eastwood J. P. , Balogh A. , Dunlop M. W. , Horbury T. S. , Dandouras I.
Published: December 2002

Cluster observations of ULF waves in the terrestrial foreshock are presented. Four spacecraft timing techniques on magnetic field measurements are used with plasma bulk velocity measurements to determine wave properties in the plasma rest frame. Based on the propagation speed and polarisation, the waves are found to be fast magnetosonic. The analysis is complemented by a direct examination of the correlation between plasma and field perturbations; consequently, an unambiguous and comprehensive identification of the wave is achieved. The advantages of the four spacecraft analysis are discussed and in particular, calculations of the propagation direction are compared to single spacecraft minimum variance techniques. The ratio of intermediate to minimum eigenvalues is used to characterise the degree to which the wave is circularly polarised. The results of a preliminary statistical survey indicate that if this ratio is greater than 10, minimum variance techniques agree closely with the four spacecraft technique.
Excitation of the FUV Io tail on Jupiter: Characterization of the electron precipitation
Authors: Gérard J.‐C. , Gustin J. , Grodent D. , Delamere P. , Clarke J. T.
Published: December 2002

Spectral observation of both polar regions of Jupiter in the far ultraviolet (FUV) obtained with the Space Telescope Imaging Spectrograph (STIS), on board the Hubble Space Telescope from July 1997 to January 2001 have been combined with FUV images to map the FUV color ratio along the STIS slit. Spatially resolved spectra of the aurora carried at ∼12 Å resolution have been used to determine the amount of methane absorption as measured by the FUV color ratio of the Io magnetic footprint and its trailing tail. It is found that the absorption is systematically less than in the main polar aurora, indicating a higher altitude source region. The color ratio of the north tail is shown to slowly decrease downstream from the footprint. The combination of these spectral data with a two‐stream model of the interaction of energetic electrons with the Jovian thermosphere indicates that the mean energy of the electrons creating the north FUV emission ranges from ∼55 keV at the Io footprint to ∼40 keV, 20 degrees downstream in the tail. In parallel, the incident electron energy flux drops by a factor ∼6 over the same angular distance. These observations are consistent with the steady state slippage picture where the subcorotating flux tube is accelerated very slowly up to corotation owing to the nonideal coupling. It is argued that small deviations from corotation can supply sufficient energy to fuel the observed auroral emissions. It is suggested that the parallel electric field accelerating electrons out of the flux tube only moderately depends on the time elapsed since the contact with Io, although the mapping between a point in the tail and Io is very uncertain in the presence of magnetic field line slippage.
Seasonal structures of upper layer circulation in the southern South China Sea from in situ observations
Authors: Fang Wendong , Fang Guohong , Shi Ping , Huang Qizhou , Xie Qiang
Published: December 2002

Conductivity‐temperature‐depth and acoustic Doppler current profiler data from six cruises spanning 1989 to 1999 are used to investigate the seasonal structure of the upper layer circulation in the southern South China Sea (SCS). The surveys were made during winter, late spring, summer, and late fall. More detailed structures not presented in previous studies are found. In summer the upper layer circulation of the southern SCS is dominated by an anticyclonic gyre with a strong eastward flow on its northern border, which originates off the southeast coast of Vietnam: the Summer Southeast Vietnam Offshore Current. In winter a stronger cyclonic gyre exists in the western portion of the southern SCS and a weaker anticyclonic circulation in the eastern portion. At the juncture of these two gyres, there is a strong northward upwind flow, called the Winter Natuna Off‐Shelf Current. In late spring the anticyclonic gyre begins to form in the northwest, and a trace of the Natuna Off‐Shelf Current can still be observed, especially subsurface in the southern part of the study area. Mesoscale eddies are active in this period. In late fall the winter‐type pattern begins to appear. The Natuna Off‐Shelf Current and the cyclonic gyre in the northwest part of the southern SCS emerge, and the summer anticyclonic gyre vanishes. In the southeast the currents are basically toward the northeast with an anticyclonic trend, revealing a multi‐eddy feature. These upper ocean currents appear consistent with the wind forcing.
NOx during background and ozone depletion periods at Alert: Fluxes above the snow surface
Authors: Beine Harald J. , Honrath Richard E. , Dominé Florent , Simpson William R. , Fuentes Jose D.
Published: December 2002

Measurements of nitric oxide (NO) and nitrogen dioxide (NO2) at Alert, Nunavut, Canada showed median background mixing ratios of 0.2 and 1.3 pmol mol−1, respectively, during darkness in late winter 2000, and 2.8 and 10.8 pmol mol−1 during spring in 24‐hour light. Both NO and NO2 showed clear diurnal cycles with noontime maxima during spring. In darkness, no NOx exchange between the snow surface and the overlying atmosphere was detected. During the period of 24‐hour sunlight, the snow surface constituted a source of NOx, whose noon‐time flux reached approximately 40 nmol m−2 h−1. Measured NOx fluxes were roughly equal to HONO fluxes reported during the Alert campaign. The fluxes were correlated to ultraviolet light intensity, but anticorrelated to wind speeds. During 2 days of high wind speeds under O3 depletion conditions, the fluxes were not significantly different from zero. However, under low wind speeds during the O3 depletion event, the snowpack continued to emit a detectable NOx flux. The observed release of NOx and HONO during the sunlit period was small relative to the observed decrease in the snowpack surface‐layer nitrate inventory. Finally, as part of this study, the nitrous acid (HONO) interference in the Xe‐lamp‐based photolytic NO2 measurements was determined; it amounted to 24% of the HONO mixing ratio.
Black carbon radiative heating effects on cloud microphysics and implications for the aerosol indirect effect 1. Extended Köhler theory
Authors: Conant William C. , Nenes Athanasios , Seinfeld John H.
Published: December 2002

Black carbon (BC) aerosol absorbs sunlight that might have otherwise been reflected to space and changes the radiative heating of the atmosphere and surface. These effects may alter the dynamical and hydrological processes governing cloud formation. A new, microphysical, effect of BC on climate is identified here, in which solar heating within BC‐containing cloud condensation nuclei (CCN) slows or prevents the activation of these CCN into cloud drops. Solar‐heated BC‐containing droplets are elevated in temperature by fractions of a degree above the ambient, thus raising the droplet vapor pressure and inhibiting activation of the most absorptive CCN. This paper develops the theory describing the alteration of the Köhler curve (i.e., the equilibrium vapor pressure over a droplet as a function of water uptake) as a function of CCN size and BC fraction. The effect is most significant in those CCN that contain volumes of BC larger than a 500 nm diameter sphere. For an aerosol population with 10% BC mass fraction per particle, solar heating can cause a 10% reduction in the CCN concentration at 0.01% critical supersaturation. On the other hand, the effect of heating by BC absorption on CCN activation above ∼0.1% critical supersaturation is negligible.