bluuebunny/crossref_metadata_2025 huggingface dataset:
A computational method using genetic algorithms for obtaining Stackelberg solutions to two‐level linear programming problems
Authors: Nishizaki Ichiro , Sakawa Masatoshi , Niwa Keiichi , Kitaguchi Yasuhiro
Published: August 2002

Stackelberg solutions have been derived for two‐level linear programming problems using genetic algorithms which in recent years have shown their efficacy in optimization problems having discrete variables. Two‐level linear programming problems are converted into single‐level programming problems by including the optimal conditions of lower‐level problems in the conditions of higher‐level problems. The obtained one‐level programming problems become 0–1 mixed programming problems. A computational method for obtaining Stackelberg solutions by generating initial population and using corresponding genetic operators based on the characteristics of the problems by expressing the 0–1 variables as individuals of the genetic algorithms is proposed. The efficacy of the proposed method is shown in computational experiments by comparing it with the variable elimination method. © 2002 Scripta Technica, Electron Comm Jpn Pt 3, 85(6): 55–62, 2002
Optimizing method using frequency annealing: Escape from a local minimum by approximate descent estimation of a low‐pass filter using neighbor data
Authors: Tomikawa Yoshihiro
Published: August 2002

This paper proposes frequency annealing (FA) as an optimization method which searches for the global optimal solution without using the derivative of the objective function. FA detects the global optimal solution efficiently by smoothing the objective function with a low‐pass filter. The gradient of the low‐pass filter, which is defined by a convolution integral, is approximated by the value of the objective function at a finite number of evaluation points defined according to the Gaussian probability density function. Thus, a gradient method without using the derivative of the objective function is realized. The effectiveness of the approximation of the low‐pass filter gradient is verified by the variance analysis of the approximation value. It is shown that by defining the neighbor points with an adequate probability density function, the approximation accuracy is made independent of the dimension M. The usefulness of the approach is demonstrated by a two‐dimensional problem and a simulation of perceptron training. FA can detect the global optimal solution even when the objective function has a local minimum or a discontinuity. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 85(8): 38–50, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.1111
The nonstandard FDTD method for three‐dimensional acoustic analysis and its numerical dispersion and stability condition
Authors: Kudo Hironori , Kashiwa Tatsuya , Ohtani Tadao
Published: August 2002

Recently, the present authors have applied the FDTD (Finite‐Difference Time‐Domain) method to acoustic problems. FDTD is one of the finite‐difference methods in the time domain used in electromagnetic problems. However, in this method, phase errors cannot be neglected in a large‐scale propagation analysis such as indoor acoustic propagation and they cause problems in the analysis. In order to reduce the phase error, Cole has invented the NS‐FDTD (Non‐Standard FDTD) method for electromagnetic problems. However, the numerical dispersion and stability condition are not described in Cole's paper. Also, the definition is given only for a cubic lattice. In this paper, an application of the three‐dimensional NS‐FDTD method to acoustic problems is attempted. Further, the method is extended to a rectangular lattice. The numerical dispersion and stability condition of the present method are derived. As a result, it is shown that the present method has much higher accuracy than the FDTD method. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 85(9): 15–24, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.1115
Measurement of arc properties and spectrum intensity in AC arcs surrounded by plastics
Authors: Ito Hiroyuki , Sakuta Tadahiro , Kobayashi Tadashi
Published: August 2002

This paper describes experimental results on the arc‐quenching properties under the condition of being surrounded by plastic found in low‐voltage circuit breakers. The alternating current used is from 500 to 1100 A(rms) with 60‐Hz frequency. The plastic materials investigated here are polymethylpentene (C3H5), polymethylmethacryl‐ate (C5H8O2), polybutyleneterephthalate (C12H14O4), polycarbonate (C16H18O3), and PTFE (C2F4). In conjunction with the usual arc current and voltage measurements, two images of spectrum intensity of 511 and 522 nm emitted from copper electrode vapor are detected simultaneously by using two bandpass filters. A high‐speed digital video technique (4500 frames per second) is used for analyzing the transient space movement of copper vapor.

The arc voltage is strongly influenced by the plastic materials rather than the arc current. Especially in the case of C3H5, the magnitude of the arc current was strongly limited by its high arc voltage. On the other hand, in the case of C2F4, the arc cannot be interrupted and the arc voltage is the lowest value of all. The arcing period is also much influenced by the type of plastic material (the shortest and longest were C3H5 and C2F4, respectively), while it shows almost no change with amplitude of arc current. The spectroscopic images of copper vapor obtained by high‐speed video for transparent plastics of C5H8O2 and C16H18O3 showed that the vapor expanding speed of the former is considerably faster than that of the latter. The results indicate strongly that the arc‐quenching property is affected by the ablation and blast speed of arc‐surrounding plastic materials. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 140(1): 38–47, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10002
Magnetic circuit design method for magnetic force control systems using inverse magnetostrictive effect: Examination of energy conversion efficiency depending on ΔE effect
Authors: Ueno Toshiyuki , Qiu Jinhao , Tani Junji
Published: August 2002

A new magnetic force control method using giant magnetostrictive material (GMM) was proposed and its feasibility was confirmed in earlier studies by the authors. This new method is based on the inverse magnetostrictive effect and the magnetic force is controlled by changing the stress or strain in the magnetostrictive material. This method is expected to have lower heat generation and higher energy conversion efficiency compared to traditional methods, since a constant magnetic force can be maintained by merely applying a constant stress. In this study, the energy conversion efficiency of this method is investigated experimentally using a universal test machine. The input elastic energy was calculated from the stress‐strain loading curve and the converted magnetic energy was estimated from the generated magnetic field. Since the elastic energy is strongly dependent on the history of the strain‐stress loading curve, and the loading curve is affected by the applied magnetic field in the magnetostrictive material, it is important to optimize the bias magnetic field for maximum energy conversion efficiency. The relationships between the elastic modulus and the magnetic field were measured experimentally and the results show that the bias magnetic field must be carefully chosen to obtain high efficiency of energy conversion. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 140(1): 8–15, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10026
Effective impedance of magnetically insulated transmission lines with geometrical discontinuity
Authors: Hiraoka Kazuki , Nakajima Mitsuo , Shiho Makoto , Horioka Kazuhiko
Published: August 2002

Space‐charge electrons transport a considerable fraction of the current in magnetically insulated transmission lines (MITLs). When an MITL has geometrical discontinuity, the interaction between the disturbed electronics and the nonlinearly coupled electromagnetic field makes their behavior difficult to predict. In this paper, the power flow through such MITLs is discussed by means of a particle simulation code and an analytical model. The results show that the space‐charge electrons tend to maintain the effective impedance of the transmission line by changing the distribution and the boundary of the space charge flow. Although a fraction of the space charge flow shunts the gap when the discontinuity is larger than the critical value, the total current upstream of the discontinuity is still preserved. © 2001 Scripta Technica, Electr Eng Jpn, 135(4): 9–16, 2001
UV laser generation in GdYCOB crystal
Authors: Furuya Hiroyuki , Nakao Hiroshi , Yoshimura Masashi , Mori Yusuke , Sasaki Takatomo
Published: August 2002

We have developed a new rare‐earth calcium oxyborate crystal GdxY1‐xCa4O(BO3)3 (GdYCOB) in order to control birefringence in nonlinear optical crystals. This GdYCOB has been grown by the Czochralski technique. In addition, we have succeeded in generating noncritically phase‐matched (NCPM) second and third harmonics of Nd:YAG laser radiation. We observed two types of photoinduced damage in high‐power third‐harmonic generation (THG). We report the prevention of these kinds of damage by means of an elevated crystal temperature and describe THG performance in the GdYCOB crystal. © 2001 Scripta Technica, Electr Eng Jpn, 136(2): 26–30, 2001
Analysis of ferrite orthogonal core for high‐frequency region based on three‐dimensional nonlinear magnetic circuit
Authors: Ichinokura Osamu , Yoshida Hiroshi , Tajima Katsubumi
Published: August 2002

This paper presents an operating analysis of a ferrite orthogonal core for high‐frequency power control and power conversion. The analysis is based on the three‐dimensional nonlinear magnetic circuit of the orthogonal core, and is called Reluctance Network Analysis. The magnetization characteristics of the ferrite orthogonal core are calculated accurately by using Reluctance Network Analysis. On the basis of the obtained magnetization curves, we can analyze the operating characteristics of the various application circuits of the orthogonal core. For an example, the control characteristics of a high‐frequency variable inductor using the ferrite orthogonal core are calculated in this paper. © 2001 Scripta Technica, Electr Eng Jpn, 137(4): 10–17, 2001
Application of time‐frequency analysis for EMC study of a power conversion system
Authors: Akamatsu Keiji , Michihira Masakazu , Funaki Tsuyoshi , Kawasaki Zenichiro , Matsuura Kenji
Published: August 2002

In recent years, the harmonics and EMI noise sent out from an electric power conversion system have attracted a great deal of attention in electromagnetic environment problems, so that the above considerations have become important. Therefore, there is a need for a detailed frequency analysis, for example, of transient phenomena during switching. We thus have proposed an analytic technique using the wavelet transform, in which it is possible to detect a phenomenon in terms of both time and frequency. In this paper, we perform an analysis using a wavelet transform on actual measured data at the switching interval. Then, based on the results obtained, we demonstrate the high validity of the wavelet transform and its application to the field of power electronics. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 140(1): 48–56, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.1170
An efficient method to compute closest loadability limit in power systems
Authors: Harada Shigemi , Yorino Naoto , Sasaki Hiroshi
Published: August 2002

A closest loadability limit (CLL) is considered as a most reliable index in the assessment and enhancement of voltage stability of a power system. Two kinds of methods, the iterative method and the direct N‐R method, have been proposed so far, but the computation of CLL is known to be troublesome. The former method is quite time‐consuming and its convergence is sometimes distributed due to the existence of multiple local CLLs, while the latter method is hardly useful unless a very accurate initial condition is available.

This paper proposes a new method to compute a CLL, consisting of three stages of computations. The first stage is to obtain a rough initial estimate of a CLL, where multiple local CLLs can be approximated by the multiple load flow solutions. The initial estimate is refined by the second stage computation based on a method similar to the conventional iterative method. The third stage is to obtain a direct solution by mean of the N‐R method. The effectiveness of the proposed method is demonstrated using IEEE 14, 30, 57, and 118 bus test systems. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 140(1): 57–67, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.1171
Growth mechanism of electron density in radio frequency afterglow plasmas
Authors: Ohtsu Yasunori , Shimizu Koji , Fujita Hiroharu
Published: August 2002

Temporal evolutions of electrons have been investigated on extinction process in radio frequency (RF) afterglow plasmas using various gases. The electron density was found to increase just after the RF power was switched off, and then decayed. This density growth depended on the gas pressure and gas mixture ratio, especially the amount of Ar gas. The growth mechanism has been studied by considering collisions between the metastable atoms to account fully for the results. © 2001 Scripta Technica, Electr Eng Jpn, 135(2): 26–32, 2001
A proposal of a WDM transmission system using three wavelength bands of 1.3, 1.47, and 1.55 μm employing optical amplifers
Authors: Yamashita Ikuo , Seikai Shigeyuki , Sawa Shinnosuke
Published: August 2002

A WDM transmission system using the wavelength bands of 1.3, 1.47, and 1.55 μm is proposed. Selection of these wavelengths makes it possible to use off‐the‐shelf optical couplers and to apply known types of amplifiers. Among three kinds of optical amplifiers, Tm3+‐doped fiber amplifiers for the 1.47 μm band are constructed and their basic properties are determined experimentally. Crosstalk between the 1.47‐ and 1.55‐μm bands originating from insufficient isolation of the couplers and Raman scattering becomes negligibly small by considering the combination of the couplers and reducing the input optical power to the single mode fiber (SMF) to below 6 dBm. Experiments on repeaterless transmission over a 50‐km SMF show error‐free performance in the 10 Gb/s × 6 WDM case where two light signals of different wavelength are launched in each band. Finally, the utility of the 1.47‐μm band is discussed theoretically. © 2001 Scripta Technica, Electr Eng Jpn, 135(2): 43–51, 2001
Waste Minimisation Clubs: a cost‐efficient policy instrument?
Authors: Henningsson Stefan , Pratt Rachel M. , Phillips Paul S. , Hyde Katherine
Published: August 2002

The total amount of solid waste generated in Europe is estimated to grow by 10% every year and there is increased concern over the associated environmental impacts. As a result, the minimization of waste at source in business and industry is a top priority in the European Community's waste strategy.

In the UK, regional Waste Minimisation Clubs (WMCs) have been established to promote sustainable waste management in business and industry. The company clusters taking part in these clubs have reported financial savings combined with reductions in environmental impact. These results are disseminated to encourage further savings by the UK industry.

This paper examines the savings as well as the costs involved in ten WMCs. It finds that there is a lack of standardization in the reporting of WMC results. This makes it difficult to evaluate the influence of WMCs, whilst also having an adverse effect on the credibility of waste minimization in business. Despite these problems, the paper finds that there is still strong evidence to suggest that these ten WMCs have been efficient in stimulating cost savings by industry, with an average rate of return on investment of 170%. It also finds that the financial benefits for companies are key outcomes of WMCs and that these benefits significantly exceed the estimated social benefits of the reduced environmental burden. Copyright © 2001 John Wiley & Sons, Ltd and ERP Environment.
Inherited predisposition and breast cancer: Modifiers of BRCA1/2‐associated breast cancer risk
Authors: Rebbeck Timothy R.
Published: August 2002

Germline mutations in the BRCA1 and BRCA2 (BRCA1/2) genes explain a substantial proportion of hereditary breast and ovarian cancer. Women who have inherited a mutation in one of these genes are at increased risk to develop breast and/or ovarian cancer, although there is variability in the manifestation of tumors by age and site. This variability may be explained, in part, by the BRCA1/2 mutation type or location. However, it is also possible that risk‐modifying factors exist that explain interindividual variability in cancer risk. These factors include genes at other loci and endogenous or exogenous exposures. A more complete understanding of factors that modify cancer risk in BRCA1 and BRCA2 mutation carriers may help to refine estimates of cancer risk. A number of exposures, including reproductive history and exogenous hormone use, have been implicated as BRCA1/2‐associated cancer risk modifiers. Similarly, genes involved in hormone metabolism, including the AIB1 and AR genes, have been linked with altered breast cancer risk. Therefore, although germline BRCA1/2 mutations raise a woman's breast and ovarian cancer risk, other factors may interact with BRCA1/2 mutations to modulate this risk. Environ. Mol. Mutagen. 39:228–234, 2002. © 2002 Wiley‐Liss, Inc.
Dermal benzene and trichloroethylene induce aneuploidy in immature hematopoietic subpopulations in vivo
Authors: Giver Cynthia R. , Wong Rosemary , Moore Dan H. , Pallavicini Maria G.
Published: August 2002

Accumulation of genetic damage in long‐lived cell populations with proliferative capacity is implicated in tumorigenesis. Hematopoietic stem cells (hsc) maintain lifetime hematopoiesis, and recent studies demonstrate that hsc in leukemic patients are cytogenetically aberrant. We postulated that exposure to agents associated with increased leukemia risk would induce genomic changes in cells in the hsc compartment. Aneusomy involving chromosomes 2 and 11 in sorted hsc (Lin−c‐kit+Sca‐1+) and maturing lymphoid and myeloid cells from mice that received topical doses of benzene (bz) or trichloroethylene (TCE) was quantified using fluorescence in situ hybridization. Six days after bz or TCE exposure, aneuploid cells in the hsc compartment increase four‐ to eightfold in a dose‐ and schedule‐independent manner. Aneuploid lymphoid and myeloid cells from bz‐ and TCE‐treated mice approximate controls, except after repeated benzene exposures. Aneuploid cells are more frequent in the hsc compartment than in mature hematopoietic subpopulations. Hematotoxicity was also quantified in bz‐ and TCE‐exposed hematopoietic subpopulations using two colony‐forming assays: CFU‐GM (colony‐forming units/granulocyte‐macrophage progenitors) and CAFC (cobblestone area–forming cells). Data indicate that bz is transiently cytotoxic (≤1 week) to hsc subpopulations, and induces more persistent toxicity (>2 weeks) in maturing, committed progenitor subpopulations. TCE is not hematotoxic at the doses applied. In conclusion, we provide direct evidence for induction of aneuploidy in cells in the hsc compartment by topical exposure to bz and TCE. Disruption of genomic integrity and/or toxicity in hsc subpopulations may be one step in leukemic progression. Environ. Mol. Mutagen. 37:185–194, 2001. © 2001 Wiley‐Liss, Inc.
Gene‐ and tissue‐specificity of mutation in Big Blue® rats treated with the hepatocarcinogen N‐hydroxy‐2‐acetylaminofluorene†
Authors: Chen Tao , Mittelstaedt Roberta A. , Shelton Sharon D. , Balachandra Dass S. , Manjanatha Mugimane G. , Casciano Daniel A. , Heflich Robert H.
Published: August 2002

In a previous study, we found that treating transgenic Big Blue® rats with the hepatocarcinogen N‐hydroxy‐2‐acetylaminofluorene (N‐OH‐AAF) produced the same major DNA adduct in the target liver and the nontarget spleen lymphocytes and bone marrow cells, induced lacI mutants in the liver, and induced much lower frequencies of lacI and hprt mutants in spleen lymphocytes. In the present study, sequence analysis was conducted on lacI DNA and hprt cDNA from the mutants, to determine the mutational specificity of N‐OH‐AAF in the rat. All the mutation spectra from N‐OH‐AAF–treated rats differed significantly from corresponding mutation profiles from untreated animals (P = 0.02 to P < 0.0001). Although there were similarities among the mutational patterns derived from N‐OH‐AAF–treated rats (e.g., G:C → T:A transversion was the most common mutation in all mutation sets), there were significant differences in the patterns of basepair substitution and frameshift mutation between the liver and spleen lymphocyte lacI mutants (P = 0.02) and between the spleen lymphocyte lacI and hprt mutants (P = 0.04). Also, multiplex PCR analysis of genomic DNA from the hprt mutants indicated that 12% of mutants from treated rats had major deletions in the hprt gene; no corresponding incidence of large deletions was evident among lacI mutations. All the mutation profiles reflect the general mutational specificity of the major DNA adduct formed by N‐OH‐AAF. The differences between N‐OH‐AAF mutation in the endogenous gene and transgene can be partially explained by the structures of the two genes. The tissue‐specificity of the mutation spectra may contribute to targeting tumor formation to the liver. Environ. Mol. Mutagen. 37:203–214, 2001. Published 2001 Wiley‐Liss, Inc.
Usefulness of genetic susceptibility and biomarkers for evaluation of environmental health risk
Authors: Au William W. , Oh Hye Young , Grady James , Salama Salama A. , Heo Moon Young
Published: August 2002

Recent attention is focused on understanding the genetic basis for individual susceptibility to the development of chronic disease. An emphasis is concentrated on establishing an association between inheritance of polymorphic chemical metabolizing genes and development of environmental cancer (e.g., lung cancer among cigarette smokers). The early reports of such associations have been very encouraging. However, some reported positive associations were not substantiated in subsequent studies using larger sample sizes and different ethnic populations. In this review, some confounding factors that contribute to the discrepancies are presented (e.g., ethnic‐dependent distribution of variant gene alleles, differential expression of metabolizing genes, and inadequate study design). It is possible that the precision of the association can be improved if the mentioned investigations are complemented with concurrent studies of biological activities/effects. The usefulness of integrating metabolic susceptibility with biomarker measurement for understanding the development of lung cancers is presented. The importance of using adequate sample size and experimental design is emphasized. Development of a reliable approach for prediction of environmental disease not only will provide fundamental information regarding the genetic basis of human disease but will be useful for reducing disease burden in the population and for advancing patient care. Environ. Mol. Mutagen. 37:215–225, 2001. © 2001 Wiley‐Liss, Inc.
Effect of mutagen‐induced cell lethality on the dose response of germline mutations
Authors: Lee William R. , Perantie Dana C. , Clark Kristin B. , Guillot Dixie A. , Wilson Vincent L.
Published: August 2002

Molecular tests for mutations require a sample of tissue from which DNA is extracted, to determine the presence or absence of one or more mutations per sample. To ensure mutation fixation each sample must consist of an equal number of cells that have had one or more DNA replications. In an in vivo test, surviving stem cells compensate to give the same number of cells per sample, leaving as the only evidence for stem cell lethality the increase in mutants of clonal origin because the mutant clone developed from a population of fewer stem cells. A problem is that an increase in mutagen dose increases stem cell death, resulting in a decreased number of surviving target cells, thus giving a downward bias of samples with one or more mutations per sample. To compare in vivo tests with molecular tests we will use as a model system the sex‐linked recessive lethal (SLRL) test for germ cell mutations in Drosophila melanogaster. Spermatogonia cells in male larvae were exposed to ENU and mutations detected in sperm cells from adults. The same SLRL data were analyzed by two methods: (1) The conventional analysis of SLRL data, in which each mutation of a cluster of mutations of common origin was counted. (2) An analysis was used to simulate a sample for molecular analysis by determining mutations per male with an equal size sample of progeny per male. With this second analysis a correction factor is required based on the change in cluster size of mutants of common origin. Environ. Mol. Mutagen. 37:340–344, 2001 © 2001 Wiley‐Liss, Inc.
Characteristics of mutations generated through digestion with restriction enzyme and ligation in plasmid DNA
Authors: Nakamura Shingo , Ikehata Hironobu , Ono Tetsuya
Published: August 2002

Recently, the use of restriction enzymes has been extended to studies in which rare events such as mutation and mistakes in DNA repair are examined. In these studies, the specificity of restriction enzymes becomes critical. To clarify the nature of the rare unexpected events occurring in the process of cutting of DNA with restriction enzymes then ligating it, we studied the molecular characteristics of unexpected plasmid DNAs that were retrieved as mutants of the plasmid after transfection to E. coli. The plasmid used was pUR288, containing lacZ as a marker of mutation. It was digested with restriction enzymes under the conditions recommended by the supplier of the enzymes and under the presence of DMSO, which is known to induce star activity of the enzymes. Comparisons of mutant frequencies and of nucleotide sequences of the mutants found in the different conditions indicated that nonspecific endonucleolytic activity similar to that found under star activity was present under the recommended conditions and, further, was responsible for the creation of deletion‐type mutations. The frequency of these events ranged from 10−5 to 10−3, depending on the kind of restriction enzymes analyzed. Although the levels of the nonspecificity were not high, they should be considered in assays such as mutation and mistakes in DNA repair, where rare events are examined. Environ. Mol. Mutagen. 38:46–54, 2001 © 2001 Wiley‐Liss, Inc.
Cleaner energy production in industrial recycling networks
Authors: Korhonen Jouni , Savolainen Ilkka
Published: August 2002

This paper considers the possibility to develop cleaner energy production with a perspective on regional material and energy flow management. The co‐production method of district and industrial heat/steam and electricity (of heat and power, CHP) using renewable or waste fuels is viewed as a physical anchor tenant function for locally based industrial recycling networks. Arguably, this production method may be used to enhance the integration of producers as well as end‐consumers into a local recycling network of matter and energy. Copyright © 2001 John Wiley & Sons, Ltd. and ERP Environment
Use of secondary information in space–time statistics for biomonitoring studies of saline deposition
Authors: Figueira Rui , Sousa António J. , Pacheco Adriano M. G. , Catarino Fernando
Published: August 2002

Atmospheric salinity is often neglected in studies of atmospheric pollution, despite its proven hazardous effects in man‐made structures, vegetable organisms (crops and natives) and soil/water resources. Biomonitoring with lichens, which has been extensively used in assessing metal element deposition, was applied to the measurement of the deposition of saline elements, in a sampling programme established on the south‐west coast of Portugal, for a period of 52 months. The concentration of chloride and sodium, used as tracers of saline deposition, was measured in thalli of Ramalina spp., and was shown to be dependent on the distance from the coast, the intensity of rain observed before the sampling date and the dry period before sampling. These three factors were used in the definition of a space–time multiplicative regression model that reproduces the space–time trend of the data, and was used as secondary variable in kriging with external drift. Results of kriging estimation on a generalized space–time domain, showed better results when using secondary information as external drift, in comparison with ordinary kriging results. Copyright © 2001 John Wiley & Sons, Ltd.
Testing whether samples of blue‐green algae have the same cell density
Authors: Laslett Geoff M. , Correll Ray
Published: August 2002

The toxicity of a blue‐green algae sample is a function of its cell density, so it is important to know if related samples in a set have different cell densities. Several plausible tests of the null hypothesis of no difference are proposed. Our study assumes that cells are counted in the laboratory using inverse Poisson sampling of blue‐green algae colonies, a common Australian technique. In the case of two samples, four standardized difference tests and two likelihood ratio tests are compared on a suite of simulated samples. One of the likelihood ratio tests assumes that colony size has a gamma distribution, but the other makes no explicit assumption. All tests are found to have virtually the same power, but the standardized difference test on the log scale and the likelihood ratio tests have nearly invariant standard null distributions and hence are more convenient to use. The semi‐parametric likelihood ratio test generalizes to the multi‐sample case very easily. Its performance on three samples is investigated, and found to be satisfactory. Copyright © 2001 John Wiley & Sons, Ltd.
Simulations of the probability structure of a dispersing, passive scalar
Authors: Zimmerman William B.
Published: August 2002

It is established that there is a time asymptotic dependency of the higher order moments of concentration on the lowest three moments through statistical analysis of field plume releases [Mole and Clarke, 1995]. A microscale model of a diffusion layer randomly buffeted by supercloud size eddies and a model of advection and diffusion in a deterministic helical eddy both demonstrated that this slaving of the higher moments to lower moments obtains time‐asymptotically and collapses with all intermittency factors onto a universal curve for kurtosis against skewness. In this article, this universality with residence time and intermittency factor obtains in two distinct plume models for transverse dispersion – diffusion within a 1‐D lamellae structure and during advection by a 2‐D random streamfunction. In the latter case, some evidence for Chatwin's closure hypothesis relating the expectation of the norm square of the gradient of the concentration, conditional at a given concentration, and the pdf of concentration, is presented. At early residence times in the plume, the power law hypothesis is consistent with simulations to a good degree. At intermediate residence times, however, there are apparently two branches to the proposed relationship, one matching Chatwin's hypothesis. Although not tested here, at long residence times the hypothesis should hold under the simulation scheme as it asymptotes to the assumptions of Chatwin's theory. Copyright © 2001 John Wiley & Sons, Ltd.
A simple two‐stage model for cancer risk in the environment
Authors: Hanayama Nobutane
Published: August 2002

A simple two‐stage (STS) model for cancer death rates on the Lexis diagram is proposed to project cancer risk in the environment, and the identifiability, the existence and consistency of MLEs for the parameters in the proposed model are discussed. From the results of fitting STS and the age‐period‐cohort (APC) model to the data obtained in Japan it is seen that the STS model provides a better fit to the data than the APC model even though the STS model has a smaller number of parameters than the APC model. Further, the results suggest that there are high risks associated with the environmental pollution due to the phase of industrial revolution between 1880 and 1900, malnourishment in the period of World War II, and the environmental pollution due to the economy in the recovery and high growth period between 1950 and 1975. Copyright © 2001 John Wiley & Sons, Ltd.
Statistical tests and power analysis for three in‐vivo bioassays to determine the quality of marine sediments
Authors: van der Hoeven Nelly , Kater Belinda J. , Pieters Jan F.
Published: August 2002

Statistical tests are recommended for three marine sediment in‐vivo bioassays. In two bioassays (Corophium volutator and Echinocardium cordatum), the mortality in the sediment is compared with that in a control. An unconditional 2 × 2 test is recommended. For one bioassay (Rotoxkit MTM with Brachionus plicatilis), mortality in a dilution series of pore water is compared with the mortality in a control. The Williams test for trends is recommended.

For each of these tests the power to assess an effect has been calculated. The number of replicates recommended in the standardized test protocol only allows large effects to be observed in almost all (95 per cent) of the experiments. Given the control mortality rates estimated from a large set of controls, a power of 95 per cent will only be reached if the mortality rate in the tested sediment is over 30 per cent for C. volutator and almost 60 per cent for E. cordatum. To reach this power for bioassays with B. plicatilis, where five concentrations are compared with a control, the mortality rate in the lowest effect concentration should be about 35 per cent.

As an alternative to no effect testing, it is suggested that whether the effect of a treatment remains below some chosen minimal relevant effect (MRE) should be tested. Given an MRE at a fixed mortality rate of 25 per cent and α = 0.05, at least 55 individuals are necessary to be reasonably sure (95 per cent) that a mortality of 10 per cent will not be declared toxic incorrectly.

The tests for mortality are based on the assumption that the survival probabilities of individuals within a test vessel are independent. We have described a method to test this assumption and applied it to the data on C. volutator. Copyright © 2002 John Wiley & Sons, Ltd.
Approximate analysis methods for asymmetric plan base‐isolated buildings
Authors: Ryan Keri L. , Chopra Anil K.
Published: August 2002

An approximate method for linear analysis of asymmetric‐plan, multistorey buildings is specialized for a single‐storey, base‐isolated structure. To find the mode shapes of the torsionally coupled system, the Rayleigh–Ritz procedure is applied using the torsionally uncoupled modes as Ritz vectors. This approach reduces to analysis of two single‐storey systems, each with vibration properties and eccentricities (labelled ‘effective eccentricities’) similar to corresponding properties of the isolation system or the fixed‐base structure. With certain assumptions, the vibration properties of the coupled system can be expressed explicitly in terms of these single‐storey system properties. Three different methods are developed: the first is a direct application of the Rayleigh–Ritz procedure; the second and third use simplifications for the effective eccentricities, assuming a relatively stiff superstructure.

The accuracy of these proposed methods and the rigid structure method in determining responses are assessed for a range of system parameters including eccentricity and structure flexibility. For a subset of systems with equal isolation and structural eccentricities, two of the methods are exact and the third is sufficiently accurate; all three are preferred to the rigid structure method. For systems with zero isolation eccentricity, however, all approximate methods considered are inconsistent and should be applied with caution, only to systems with small structural eccentricities or stiff structures. Copyright © 2001 John Wiley & Sons, Ltd.
2,3‐α‐Epoxyjaeschkeanadiol 5‐benzoate from Ferula hermonis Boiss
Authors: Diab Youssef , Dolmazon René , Fenet Bernard
Published: August 2002

The new 2,3‐α‐epoxyjaeschkeanadiol 5‐benzoate has been isolated and its 1H‐ and 13C‐NMR signals were completely assigned by the application of the modern NMR techniques. Its conformations are discussed on the basis of molecular modelling calculations and nuclear Overhauser effect spectroscopy (NOESY) spectra. Copyright © 2001 John Wiley & Sons, Ltd.
Essential oil composition of Schizogyne glaberrima DC, a species endemic to the Canary Islands
Authors: Palá‐Paúl J. , Pérez‐Alonso M. J. , Velasco‐Negueruela A. , Sanz J.
Published: August 2002

The chemical composition of the volatile oil from Schizogyne glaberrima DC has been studied by GC and GC–MS. The main constituents of the oil were found to be p‐cymene (64.9%) and limonene (25.2%). This is the first report of the essential oil of this species. It is worth mentioning the presence in the oil of some thymol derivatives. Copyright © 2001 John Wiley & Sons, Ltd.
Linearization of second‐order calibration curves in stable isotope dilution–mass spectrometry
Authors: Fay Laurent B. , Métairon Sylviane , Baumgartner Marcel
Published: August 2002

The quantification of compounds using isotope dilution mass spectrometry requires the establishment of calibration curves prior to determination of any unknown sample. When calibration over a wide concentration range is required and/or when an overlap exists between internal standard and analyte ions (if mono‐ or di‐isotopically‐labelled internal standards are used), second‐order calibration curves are obtained. In this paper we have compared several calculation methods to linearize such calibration curves. We found that the method published by Bush and Trager6 gives a satisfactory linear relationship between the corrected amount ratio y = Ql(Qu+tQl) (the value Qu being the amount of unlabelled analyte, Ql the amount of labelled internal standard and t, the fixed fraction of the internal standard, which is identical to the unlabelled analyte) and the ratio of unlabelled to labelled ion intensities. All the other calculation methods that have been published so far have failed to linearize the second‐order calibration curve build‐up over a wide concentration range. Copyright © 2001 John Wiley & Sons, Ltd.
The discontinuous profile method for simulating two‐phase flow in pipes using the single component approximation
Authors: Guinot Vincent
Published: August 2002

Godunov‐type algorithms are very attractive for the numerical solution of discontinuous flows. The reconstruction of the profile inside the cells is crucial to scheme performance. The non‐linear generalization of the discontinuous profile method (DPM) presented here for the modelling of two‐phase flow in pipes uses a discontinuous reconstruction in order to capture shocks more efficiently than schemes using continuous functions. The reconstructed profile is used to define the Riemann problem at cell interfaces by averaging of the components of the variable in the base of eigenvectors over their domain of dependence. Intercell fluxes are computed by solving the Riemann problem with an approximate‐state solver. The adapted treatment of boundary conditions is essential to ensure the quality of the computational results and a specific procedure using virtual cells at both extremities of the computational domain is required. Internal boundary conditions can be treated in the same way as external ones. Application of the DPM to test cases is shown to improve the quality of computational results significantly. Copyright © 2001 John Wiley & Sons, Ltd.
On the shoreline boundary conditions for Boussinesq‐type models
Authors: Bellotti G. , Brocchini M.
Published: August 2002

We propose and illustrate a novel type of shoreline boundary conditions for Boussinesq‐type models. On the basis of characteristic equations of the non‐linear shallow water equations, boundary conditions are developed equations that can suitably model the motion of the instantaneous shoreline. Such boundary conditions are then implemented in a numerical solver for a specific set of Boussinesq‐type equations, which have been proved very effective for near‐shore modelling. Finally, a number of tests are performed to validate and illustrate the behaviour of the new conditions. Copyright © 2001 John Wiley & Sons, Ltd.
Three dimensional tide‐induced circulation model on a triangular mesh
Authors: Jiang Wensheng , Sun Wenxin
Published: August 2002

In this paper a triangular mesh, which is generated by an automatic triangular mesh generator, is used to calculate the tide‐induced residual current in the Bohai Sea, China. The generator can modify the distribution of the node according to the water depth, thus ensuring the uniform distribution of the Courant number. The three dimensional nonlinear tide equation is employed to get the Eularian residual current and Stokes' drift. Then the Lagrangian residual current is obtained by adding the above two values. It has been proved in other papers that the Lagrangian residual current is more proper to represent the circulation and a numerical example is given. The application of these methods to the Bohai Sea shows that the results are in accordance with those obtained before. Copyright © 2002 John Wiley & Sons, Ltd.
A comparison of methods for bootstrapping in the local level model
Authors: Franco Glaura C. , Souza Reinaldo C.
Published: August 2002

Bootstrap in time series models is not straightforward to implement, as in this case the observations are not independent. One of the alternatives is to bootstrap the residuals in order to obtain the bootstrap series and thus use these series for inference purposes. This work deals with the problem of assessing the accuracy of hyperparameters in structural models. We study the simplest case, the local level model, where the hyperparameters are given by the variances of the disturbance terms. As their distribution is not known, we employ the bootstrap to approximate the true distribution, using parametric and non‐parametric approaches. Bootstrap standard deviations are computed and their performances compared to the asymptotic and empirical standard errors, calculated using a Monte Carlo simulation. We also build confidence intervals to the hyperparameters, using four bootstrap methods and the results are compared by means of the length, shape and coverage probabilities of the intervals. Copyright © 2002 John Wiley & Sons, Ltd.
What to do if a dollar is not a dollar? The impact of inflation risk on production and risk management
Authors: Adam‐Müller Axel F. A.
Published: August 2002

An entrepreneur faces two types of risk: one from income generation, one from income spending. His income
from firm profits is risky due to output price fluctuations and other risks. As a consumer, he is also exposed
to inflation risk since he maximizes expected utility of real income. This article focuses on optimal production
and risk management decisions of a risk‐averse entrepreneur jointly facing tradable output price risk and
untradable inflation risk. Inflation risk applies multiplicatively to the entrepreneur's entire nominal
income. Relative risk aversion and the risks' joint distribution determine the effect of introducing a
futures market on production. For dependent risks, this effect may be negative if relative risk aversion is
above one. Relative risk aversion and the joint distribution also determine optimal risk management with futures
contracts where speculation on a real risk premium and cross hedging may be conflicting objectives. © 2002
Wiley Periodicals, Inc. Jrl Fut Mark 22:371–386, 2002
Two‐State Option Pricing: Binomial Models Revisited
Authors: Jabbour George M. , Kramin Marat V. , Young Stephen D.
Published: August 2002

This article revisits the topic of two‐state option pricing. It examines the models developed by Cox,
Ross, and Rubinstein (1979), Rendleman and Bartter (1979), and Trigeorgis (1991)
and presents two alternative binomial models based on the continuous‐time and discrete‐time
geometric Brownian motion processes, respectively. This work generalizes the standard binomial approach,
incorporating the main existing models as particular cases. The proposed models are straightforward and
flexible, accommodate any drift condition, and afford additional insights into binomial trees and lattice models
in general. Furthermore, the alternative parameterizations are free of the negative aspects associated with the
Cox, Ross, and Rubinstein model. © 2001 John Wiley & Sons, Inc. Jrl Fut Mark 21:987–1001,
2001
Discordance of genetic alterations between primary head and neck tumors and corresponding metastases associated with mutational status of the TP53 gene
Authors: Tabor Maarten P. , van Houten Viola M. M. , Kummer J. Alain , Vosjan Maria J. W. D. , Vlasblom Ronald , Snow Gordon B. , Leemans C. René , Braakhuis Boudewijn J. M. , Brakenhoff Ruud H.
Published: August 2002

Ample molecular data are available on the progression from normal mucosa to invasive head and neck squamous cell carcinoma (HNSCC), but information on further genetic progression to metastatic disease is scarce. To obtain insight into the metastatic process, we compared 23 primary HNSCCs with 25 corresponding lymph node metastases (LNMs) and 10 corresponding distant metastases (DMs) with respect to TP53 mutations and patterns of loss of heterozygosity (LOH) based on 26 microsatellite markers on six chromosome arms (3p, 9p, 17p, 13q, 8p, and 18q). In 18 of the 23 patients, a TP53 mutation was detected in the primary tumor, and in all cases the same TP53 mutation was present in the corresponding LNM or DM. In nine of 20 patients with LNMs and three of seven patients with DMs, the LOH pattern of metastasis differed from that of the corresponding primary tumor by at least one marker. Microsatellite markers located on chromosome arms 13q, 8p, and 18q were most frequently discordant, providing evidence that alterations at these chromosomes occur late in HNSCC carcinogenesis. Moreover, evidence was found that DMs had developed directly from the primary tumor and not from LNMs. Remarkably, we observed that the mutational status of the TP53 gene is associated significantly with the degree of genetic differences between primary HNSCCs and corresponding metastases. All patients with TP53 wild‐type primary tumors showed significantly more discordant LOH patterns in the corresponding LNMs and DMs than patients with TP53‐mutated tumors. The percentages were 100% versus 27% (LNMs) and 100% versus 0% (DMs), respectively (P = 0.008 and P = 0.029; two‐sided Fisher exact test). This finding suggests that TP53‐mutated tumors need fewer additional genetic alterations to develop metastases compared with TP53 wild‐type primary tumors. © 2002 Wiley‐Liss, Inc.