bluuebunny/crossref_metadata_2025_split huggingface dataset:
Parameter estimation and bit error rate of optimum receiver in a class‐A impulsive radio noise environment
Authors: Kanemoto Hideki , Miyamoto Shinichi , Morinaga Norihiko 
Published: March 2003

AbstractSince most of the noise generated by electronic equipment using high‐frequency devices has statistical properties that are quite different from Gaussian noise, the bit error rate of conventional receivers is greatly degraded in a man‐made noise environment, because they are designed with the presumption of Gaussian noise. One of the methods of providing a better bit error rate in such a noise environment is the use of an optimum receiver. This optimum receiver attains a high bit error rate by using maximum likelihood symbol detection based on the statistical properties of the noise, and the statistical properties of the noise must be known a priori for optimum reception. In this paper, we use the Middleton class‐A impulsive radio noise model as the statistical model of the noise and study the parameter estimation and bit error rate of an optimum receiver in a class‐A impulsive radio noise environment. First, we evaluate the effect of errors in parameter estimation on the bit error rate of the optimum receiver in a class‐A impulsive radio noise environment, and show that to improve the performance of the optimum receiver in this noise environment, we should use parameters that express the statistics of the noise. Next we study the relationship between the number of noise samples used in estimation and the parameter estimation accuracy, and demonstrate that large numbers of noise samples are needed for highly accurate parameter estimation. However, it is shown that a quite good bit error rate can be obtained by the optimum receiver in the noise environment even if parameter estimation is based on a somewhat smaller number of noise samples (for example, about 700 samples for an impulsive indexA= 0.05 and a Gaussian component ratio Γ′ = 0.05). © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 86(8): 68–78, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.1173
Volatility forecasting for risk management
Authors: Brooks Chris , Persand Gita 
Published: March 2003

AbstractRecent research has suggested that forecast evaluation on the basis of standard statistical loss functions could prefer models which are sub‐optimal when used in a practical setting. This paper explores a number of statistical models for predicting the daily volatility of several key UK financial time series. The out‐of‐sample forecasting performance of various linear and GARCH‐type models of volatility are compared with forecasts derived from a multivariate approach. The forecasts are evaluated using traditional metrics, such as mean squared error, and also by how adequately they perform in a modern risk management setting. We find that the relative accuracies of the various methods are highly sensitive to the measure used to evaluate them. Such results have implications for any econometric time series forecasts which are subsequently employed in financial decision making. Copyright © 2002 John Wiley & Sons, Ltd.
Market risk management of banks: implications from the accuracy of Value‐at‐Risk forecasts
Authors: Wong Michael Chak Sham , Cheng Wai Yan , Wong Clement Yuk Pang 
Published: March 2003

AbstractThis paper adopts the backtesting criteria of the Basle Committee to compare the performance of a number of simple Value‐at‐Risk (VaR) models. These criteria provide a new standard on forecasting accuracy. Currently central banks in major money centres, under the auspices of the Basle Committee of the Bank of International settlement, adopt the VaR system to evaluate the market risk of their supervised banks. Banks are required to report VaRs to bank regulators with their internal models. These models must comply with Basle's backtesting criteria. If a bank fails the VaR backtesting, higher capital requirements will be imposed. VaR is a function of volatility forecasts. Past studies mostly conclude that ARCH and GARCH models provide better volatility forecasts. However, this paper finds that ARCH‐ and GARCH‐based VaR models consistently fail to meet Basle's backtesting criteria. These findings suggest that the use of ARCH‐ and GARCH‐based models to forecast their VaRs is not a reliable way to manage a bank's market risk. Copyright © 2002 John Wiley & Sons, Ltd.
Haematological, hepatic and renal alterations after repeated oral and intraperitoneal administration of monoisoamyl DMSA. II. Changes in female rats
Authors: Flora Swaran J. S. , Mehta Ashish 
Published: March 2003

AbstractWe recently reported the effects of repeated administration of the monoisoamyl ester of dimercaptosuccinic acid (MiADMSA) on a few selected biochemical variables indicative of haematopoietic, liver, kidney and brain toxicity, oxidative stress and essential metal status in male rats. The present investigation studies similar changes in female rats to ﬁnd out if the changes are independent of gender. The results suggest signiﬁcant and pronounced toxic effects of MiADMSA on haem biosynthesis, liver and kidneys in female rats exposed to higher doses of orally (p.o.) or intraperitoneally (i.p.) administered MiADMSA, compared with the effects in male rats. No effects on brain tissues were seen. A pronounced depletion of copper was noted in the blood and liver of MiADMSA administered rats, irrespective of route of exposure. It can be concluded that the administration of MiADMSA in female rats is confounded with side‐effects and may require caution during its use and further exploration. Copyright © 2003 John Wiley & Sons, Ltd.
Kupffer cells are responsible for liver cirrhosis induced by carbon tetrachloride
Authors: Muriel Pablo , Escobar Yesenia 
Published: March 2003

AbstractInhibition of Kupffer cells could disrupt the sequence of events leading to organ injury by damping down the ﬁbrogenic stimulus. To elucidate the role of Kupffer cells in liver ﬁbrosis and cirrhosis, rats were treated with gadolinium chloride (GdCl3) and cirrhosis was induced by subchronic carbon tetrachoride (CCl4) administration. Carbon tetrachloride was administered three times per week for 8 weeks to male Wistar rats treated simultaneously with GdCl3 (20 mg kg−1, i.p. daily); appropriate controls were performed. Serum enzyme activities of alkaline phosphatase (ALP), γ‐glutamyl transpeptidase (γ‐GTP) and alanine aminotransferase (ALT) and bilirubin concentration increased signiﬁcantly by CCl4, whereas GdCl3 prevented completely the increase in γ‐GTP and partially prevented the increase in ALP, ALT and bilirubins (P < 0.05). Liver glycogen was depleted by CCl4, an effect that GdCl3 was not capable of preventing. Moreover, gadolinium by itself depleted it. Lipid peroxidation increased about 2.5‐fold by administration with CCl4, whereas GdCl3 preserved lipid peroxidation within normal values. Hepatic collagen increased threefold after subchronic intoxication with CCl4 (P < 0.05) whereas GdCl3 prevented partially (P < 0.05) the increase in collagen content, as evidenced by the liver hydroxyproline content and by the histopathological analysis. The present results suggest that Kupffer cells are needed for the production of CCl4‐induced cirrhosis, because their inactivation with GdCl3 prevents the disease. Published in 2003 by John Wiley & Sons, Ltd.
Involvement of oxidative sress in the toxicity of 4‐monochlorophenol in Hep G2 cells in culture
Authors: Trufﬁn D. , Garçon G. , Hannothiaux M. H. , Colein P. , Shirali P. , Grave‐Descampiaux B. 
Published: March 2003

AbstractChlorophenols, mainly used as biocides, are compounds with a wide spectrum of toxic effects, including teratogenic and carcinogenic actions. The aim of this study was to examine possible 4‐monochlorophenol (4‐MCP) toxicity related to metabolic pathways, which may implicate semiquinones and reactive oxygen species (ROS), in human Hep G2 cells. The effects of 4‐MCP were performed through cytotoxicity assays (viability, ATP level), metabolic activities (4‐MCP intracellular concentration, NADPH cytochrome P‐450 reductase (Cyt P‐450 red.) and glutathione‐S‐transferase activities, CYP 3A7 mRNA expression) and oxidative stress (superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase activities, glutathione status, malondialdehyde concentration, CYP 2E1 mRNA expression). According to the literature, in this work Hep G2 cells were incubated in the continuous presence of 4‐MCP at 350 μM over 24 or 48 h. Results showed statistically signiﬁcant decreases in ATP levels (24 or 48 h, P < 0.05) versus controls. The 4‐MCP intracellular concentrations increased as early as 8–24 h and then decreased (P < 0.01). Decreases in Cyt. P‐450 red. (24 h, P < 0.05), catalase (24 h, P < 0.05; 48 h, P < 0.01), glutathione peroxidase activities (48 h, P < 0.05) and reduced glutathione concentrations (48 h, P < 0.05) were observed. In addition, exposure to 4‐MCP increased mRNA expressions of CYP 3A7 (24 h, P < 0.05; 48 h, P < 0.01) and CYP 2E1 (24 h, P < 0.01) versus controls. Taken together, these results suggest that 4‐MCP metabolites could induce oxidative stress conditions in Hep G2 cells. Published in 2003 by John Wiley & Sons, Ltd.
The adrenal cortex and steroidogenesis as cellular and molecular targets for toxicity: critical omissions from regulatory endocrine disrupter screening strategies for human health?
Authors: Harvey Philip W. , Everett David J. 
Published: March 2003

AbstractCurrent testing strategies to assess the endocrine disrupting properties of chemicals have omitted examination of the adrenal gland and do not adequately cover the process of steroidogenesis. Steroidogenesis is critical for adrenocortical function as well as that of the testes and ovaries, and presents multiple molecular targets for toxicity, ranging from general effects on all steroidogenic tissues (e.g. via StAR protein or CYP11A1 cholesterol side‐chain cleavage) through to speciﬁc targets affecting only adrenocortical function (e.g. CYP11β/18 and glucocorticoid synthesis). Numerous chemicals of environmental relevance are now being shown to affect adrenocortical function both in vivo in aquatic species and in vitro in human cell lines, and given the vital role of the adrenal gland to human health and development, there is a strong case for including dedicated assessment techniques in screening batteries for endocrine‐disrupting chemicals, not least to assist in general data interpretation (e.g. whether adrenal hypertrophy is due to stress or to a more sinister adrenocortical insufﬁciency). Cell lines such as H295R (derived from a human adrenocortical adenocarcinoma) currently exist that will allow assessment of cortisol production and most of the major enzymes and functional proteins in the steroidogenic pathway (e.g. StAR; CYP11A1/scc; CYP11β/18; CYP17; CYP19; CYP21; 3β‐hydroxysteroid dehydrogenase). Adequate assessment of adrenocortical function, as with any component of the integrated endocrine system, probably also will require the development of speciﬁc in vivo methodology to include effects on hypothalamo‐pituitary function. Finally, although there is currently no direct evidence that environmental exposure to endocrine‐disrupting (oestrogenic) chemicals has actually caused adverse human health effects, lessons have been learned on their potential from the diethylstilboestrol case. Similar evidence exists from aminoglutethimide and etomidate on the lethal impact of unpredicted chemically induced adrenal insufﬁciency in sensitive human subgroups, and it would seem prudent to incorporate relevant tests for adrenal function and steroidogenesis into current regulatory validation programmes. Published in 2003 by John Wiley & Sons, Ltd.
Underarm cosmetics and breast cancer
Authors: Darbre P. D. 
Published: March 2003

AbstractAlthough risk factors are known to include the loss of function of the susceptibility genes BRCA1/BRCA2 and lifetime exposure to oestrogen, the main causative agents in breast cancer remain unaccounted for. It has been suggested recently that underarm cosmetics might be a cause of breast cancer, because these cosmetics contain a variety of chemicals that are applied frequently to an area directly adjacent to the breast. The strongest supporting evidence comes from unexplained clinical observations showing a disproportionately high incidence of breast cancer in the upper outer quadrant of the breast, just the local area to which these cosmetics are applied. A biological basis for breast carcinogenesis could result from the ability of the various constituent chemicals to bind to DNA and to promote growth of the damaged cells. Multidisciplinary research is now needed to study the effect of long‐term use of the constituent chemicals of underarm cosmetics, because if there proves to be any link between these cosmetics and breast cancer then there might be options for the prevention of breast cancer. Copyright © 2003 John Wiley & Sons, Ltd.
Pesticide residue on/in the washed skin and its potential contribution to dermal toxicity
Authors: Zendzian Robert P. 
Published: March 2003

AbstractWashing the skin of humans or experimental animals after exposure to a pesticide or other chemical may leave a major portion of the dose on/in the washed skin. Questions have been raised as to whether this skin residue can contribute to the toxicity of a pesticide by continued post‐wash absorption. In a set of 19 pesticides tested in the rat to determine the fate of this skin residue, absorption from the washed skin continued in 15 at all doses tested, continued in 2 pesticides at only some of the doses tested and did not continue in 2 volatile pesticides. However, only nine pesticides showed an increase in systemic concentration following absorption from the washed skin, which can be considered indicative of potential increased toxicity. The time of occurrence and magnitude of the increase varied with chemical and dose, being a combination of rate and magnitude of absorption and rate and magnitude of excretion of the absorbed chemical. Similar patterns of continued absorption of skin residue may be expected to occur in humans. Published in 2003 by John Wiley & Sons, Ltd.
Modeling an electrochemical process to remove Cr(VI) from rinse‐water in a stirred reactor
Authors: Rodríguez Miriam G , Aguilar Ricardo , Soto Gabriel , Martínez Sergio A 
Published: March 2003

AbstractExperimental studies were developed in a batch reactor (16 dm3), to obtain the kinetic model of Cr(VI) removal by means of an electrochemical process. An overall kinetic model was obtained and experimentally validated in a continuous stirred electrochemical reactor (16 dm3) with synthetic and industrial wastewater. To develop the mathematical model of the continuous reactor in relation to the Cr(VI) and Fe(II) concentration in the solution, a classical mass balance procedure was performed. The Cr(VI) concentration in the electrochemically‐treated waters was less than 0.5 mg dm−3. In the electrochemical process the Cr(VI) reduction is caused by the Fe(II) released from the anode due to the electric current applied, by the Fe(II) released for the dissolution (corrosion) of the electrodes due to the acidic media, and by reduction at the cathode. During the process, reduction from Fe(III) to Fe(II) occurs. All of these different reactions cause a diminution in the quantity of sludge generated. Finally, it was found that due to the slow rate of reduction of Cr(VI) during the first part of the process it is necessary to develop a method of control to apply the process in a continuous industrial system.© 2003 Society of Chemical Industry
Control of filamentous organisms in food‐processing wastewater treatment by intermittent aeration and selectors
Authors: Nakhla George , Lugowski Andrew 
Published: March 2003

AbstractVarious measures were tested at a full‐scale wastewater treatment plant to control sludge bulking by type 0041 and 0675 filamentous microorganisms, instigated by highly variable wastewater loadings from a food‐processing facility. Intermittent aeration on a 1‐h on 1‐h off basis was found to effect a marginal improvement in sludge settling characteristics, as reflected by about an 11–36% reduction in the Sludge Volume Index (SVI) to 118 cm−3 g−1. At BOD loadings of 1500 kg d−1 which marginally exceeded the design capacity of the plant of 1200 kg d−1, SVI rose sharply to 230 cm−3 g−1 in less than a week. The anoxic selector effected a reduction in SVI to 170 cm−3 g−1 within 3 weeks of operation at temperatures of 8–12 °C. The aerobic selector was most effective, reducing SVIs further to 79 cm−3 g−1 in 2 weeks. Sludge settleablity was found to be inversely proportional to the aerobic selector food‐to‐microorganism ratio. The optimum aerobic selector loading was found to be 1.8–2.7 kgBOD5 kgMLVSS d−1, with corresponding SVIs in the range of 80–120 cm−3 g−1.© 2003 Society of Chemical Industry
Nitrite accumulation characteristics of high strength ammonia wastewater in an autotrophic nitrifying biofilm reactor
Authors: Yun Ho‐Joon , Kim Dong‐Jin 
Published: March 2003

AbstractSelective nitrification was carried out to accumulate nitrite from high strength ammonia wastewater in an autotrophic nitrifying biofilm reactor. Nitrification efficiencies and nitrite accumulation characteristics were investigated at various operating conditions such as ammonium load, oxygen supply and free ammonia concentration. The biofilm reactor showed very stable nitrification efficiencies of more than 90% at up to 2 kg NH4‐N m−3 d−1 and the nitrite content was maintained at around 95%. Inhibition by free ammonia on nitrite oxidizers seems to be the major factor for nitrite accumulation. Batch kinetic analyses of ammonium and nitrite oxidation showed that nitrite oxidation activity was selectively inhibited in the presence of free ammonia. However, the activity recovered quickly as the free ammonia concentration decreased below the threshold inhibition concentration. Examination of specific ammonia and nitrite oxidation activities and the most probable number indicated that the number of nitrite‐oxidizing microorganisms in the nitrite‐accumulating system was less than that in the normal nitrification system due to long‐term free ammonia inhibition of the nitrite oxidizers. The reduced population of nitrite oxidizers in the biofilm system was also responsible for the accumulation of nitrite in the biofilm reactor.© 2003 Society of Chemical Industry
Elimination of inorganic mercury from waste waters using crandallite‐type compounds
Authors: Monteagudo José M , Durán Antonio , Carmona Manuel S , Schwab Roland G , Higueras Pablo 
Published: March 2003

AbstractThe removal of inorganic mercury from waste water streams arising from mines, using an artificial amorphous compound of the crandallite type synthesized in our laboratory, Ca0.5Sr0.5Al3(OH)6(HPO4) (PO4), has been investigated. This compound exhibits an extremely wide range of ionic substitutions: Ca2+ and Sr2+ were interchanged with Hg2+, so the mercury content of the waste water, ranging from 70 to 90 ppm, was reduced to less than 0.1 ppm. The process has been studied under batch conditions. The crandallite showed a high capacity for the exchange of mercury from mercuric nitrate solutions, 1.555 meq g−1. The ion‐exchange equilibrium isotherms for Hg2+ were correlated by the Langmuir equation. The recovery of mercury from Hg‐crandallite using HCl solutions and thermal treatment was also studied. Optimum recuperation of mercury is achieved by chemical reaction with HCl solution (pH 2.25). At these conditions, 75% of the mercury is recovered as the HgCl42− complex in a simple batch process, and the crandallite (in the protonic form) can be reused.© 2003 Society of Chemical Industry
Preparation and characterization of precipitated zinc silicates
Authors: Michalska Iwona , Krysztafkiewicz Andrzej , Bogacki Mariusz B , Jesionowski Teofil 
Published: March 2003

AbstractThe study aimed to obtain highly dispersed particles of zinc silicate, a potential filler of polymers or a paint pigment, by precipitation from solutions of sodium metasilicate and of zinc salts. The technique of silicate precipitation was worked out, and the conditions causing precipitation were optimized. The temperature, sodium metasilicate solution flow rate and concentration of zinc salts were selected so as to obtain silicates of the lowest possible bulk density, and which had low water‐absorbing capacity and high paraffin oil‐absorbing capacity. In the study, the effects of precipitation parameters were examined on the principal physicochemical properties of the silicates, the structure and uniform character of silicate particles, particle size distribution, and the surface morphology. Particular attention was devoted to the particle size distribution and the tendency to form primary agglomerates (aggregates) and secondary agglomerates, using dynamic light scattering (DLS). Studies were undertaken to develop a technique which could prevent formation of silicate particle agglomerates. With this aim, the silicates' surface was modified either during their precipitation or by the so‐called dry technique. For the modification, silane coupling agents were applied. The extent of silicate surface hydrophobicity was examined by estimation of the enthalpies of immersion of the modified silicate surface. The silicates obtained were tested as fillers of rubber mixtures (in butadiene–styrene rubber).© 2003 Society of Chemical Industry
Bioremediation of toluene‐contaminated air using an external loop airlift bioreactor
Authors: Harding Rochelle C , Hill Gordon A , Lin Yen‐Han 
Published: March 2003

AbstractAn external loop airlift bioreactor (ELAB) has been used to capture and degrade toluene from a contaminated air stream. Using a spinning sparger, the toluene could be transferred from small, uniform bubbles into the aqueous culture media with an overall mass transfer coefficient as high as 1.1 h−1. Due to the very volatile nature of toluene, Pseudomonas putida (ATCC 23973) was cultured and maintained on benzyl alcohol, the first intermediate compound in the metabolic degradation pathway for toluene. Consequently, before successful continuous operation of the ELAB with toluene‐contaminated air, Pseudomonas putida was acclimatized to toluene by using 30 min intermittent sparging of contaminated air into the bioreactor. Continuous sparging of toluene‐contaminated air could then be successfully carried out with 100% capture and biodegradation efficiency at a contaminated air concentration of 15 mg dm−3 and a loading rate of 35 mg dm−3 h−1. Higher concentrations and loading rates were only partially degraded. Although this capture matches only the low rates reported earlier using biofilters to remediate toluene, the ELAB operates using submerged culture and requires no packing which can plug during biofilter operation. In this study, Pseudomonas putida grew on toluene at a maximum specific growth rate of only 0.05 h−1.© 2003 Society of Chemical Industry
Identification and modelling of aerobic hydrolysis – application of optimal experimental design
Authors: Insel Güçlü , Orhon Derin , Vanrolleghem Peter A 
Published: March 2003

AbstractHydrolysis mechanism plays a dominant role in the delicate balance of electron donor/electron acceptor ratios in BNR and EBPR systems as an important carbon source. In this study, the surface‐saturation‐type hydrolysis kinetics was investigated based on respirometric measurements, within the context of the theoretical and the practical identifiability of mathematical models. The identifiable parameters of a selected model were derived from respirograms. In addition, the information from the experiments was evaluated on the basis of Optimal Experimental Design (OED) methodology for different initial conditions of the batch respirometric experiment.© 2003 Society of Chemical Industry