bluuebunny/crossref_metadata_2025 huggingface dataset:
A unified theory for coherent systems in reliability part III: Two special cases for multinary systems—binary‐type coherence and homogeneous coherence
Authors: Mazars N.
Published: May 2007

As shown in a companion‐paper,1binary and multinary coherent systems can be studied with unified arguments, through monotone binary coherent systems. These are binary coherent systems submitted to some monotone constraint and generalize the classic theory of free binary coherent systems. By considering the unified point of view thus obtained, this paper gives what is perhaps the most suggestive representation for multinary coherent systems, since this extends the definition of binary coherent systems in terms of series‐parallel (parallel‐series) structures. Then, this paper examines the special case of multinary systems that can be studied directly with the classic theory of free binary coherent systems. It thus enlarges and complements, in a shorter unified manner, the particular cases considered in earlier studies.
Tracking models and the optimal regret distribution in asset allocation
Authors: Dembo Ron S. , King Alan J.
Published: May 2007

We present a tracking model for asset allocation that tracks desired investment goals. The model is shown to be optimal with respect to an investor's ‘regret distribution’, the cumulative distribution of the difference between the revenue under perfect foresight and that possible without foresight. Relationships with Markowitz mean/variance models are also explored.
New concepts and algorithms for portfolio choice
Authors: Dueck Gunter , Winker Peter
Published: May 2007

The paper studies the design of optimal (bond) portfolios taking into account various possible utility functions of an investor. The most prominent model for portfolio optimization was introduced by Markowitz. A real solution in this model can be achieved by quadratic programming routines for mean‐variance analysis. Of course, there are many reasons for an investor to prefer other utility criteria than return/variance of return in the Markowitz model. In the last few years, many efficient multiple purpose optimization heuristics have been invented for the needs in optimizing telephone nets, chip layouts, job shop scheduling etc. Some of these heuristics have essential advantages: they are extremely flexible and very easy to implement on computers. One example of such an algorithm is the threshold‐accepting algorithm (TA). TA is able to optimize portfolios under nearby arbitrary constraints and subject to nearly every utility function. In particular, the utility functions need neither to be convex, differentiable nor ‘smooth’ in any sense. We implemented TA for bond portfolio optimization with different utility criteria. The algorithms and computational results are presented. Under various utility functions, the ‘best’ portfolios look surprisingly different and have quite different qualities. Thus, for a portfolio manager it might be useful to provide himself with such a ‘multiple‐taste’ optimizer in order to be able easily to readjust it according to his own personal utility considerations.
Portfolio insurance and synthetic securities
Authors: Geman Hélyette
Published: May 2007

This paper aims to look at the situation of portfolio insurance, both from a theoretical and a practical standpoint, a decade after the methodology was first introduced by Leland and Rubinstein, and a few years after management strategies based on portfolio insurance were hurt by the crash of 1987. After a general introduction in Section 1, Section 2 presents a survey of different portfolio strategies and more specifically those related to portfolio insurance. Section 3 underlines the different issues raised by the market plunge of 1987, namely the problem of volatility misspecification, and studies the possible answers offered at this point by academics and practitioners. Section 4 contains some concluding comments.
Quadratic programming for portfolio optimization
Authors: Ho Diem
Published: May 2007

Portfolio optimization is a procedure for generating a portfolio composition which yields the highest return for a given level of risk or a minimum risk for given level of return. The problem can be formulated as a quadratic programming problem. We shall present a new and efficient optimization procedure taking advantage of the special structure of the portfolio selection problem. An example of its application to the traditional mean‐variance method will be shown. Formulation of the procedure shows that the solution of the problem is vector intensive and fits well with the advanced architecture of recent computers, namely the vector processor.
Run orders and quantitative factors in asymmetrical designs
Authors: El Mossadeq A. , Koblinsky A.
Published: May 2007

Results on run orders leading to trend‐free symmetrical factorial designs are extended to the asymmetrical case, using the character theory of abelian groups. The tools developed apply equally to the construction of designs for quantitative treatment factors with eight or more regularly spaced levels. Abelian group theory can also be used to find minimum‐cost run orders for asymmetrical designs, with a cost based on the number of changes of levels between successive runs.
On the generation of high‐quality white noise series
Authors: Figwer J. , Niederlinski A.
Published: May 2007

A new approach to the simulation of white‐noise time‐series is presented. The approach is based on the frequency‐domain property of white‐noise as having a flat power spectrum density (PSD). From such a PSD, a linear complex spectrum of random‐phase multisinusoidal series (MS) may be generated. Next, the fast Fourier transform is applied to this linear spectrum to generate a random‐phase multisinusoidal N‐sample series, simulating the white‐noise series. The properties of some MS series are discussed including a gaussian white noise multisinusoidal series. The idea is illustrated by a number of examples. They demonstrate that the spectral and correlation properties of such series are enhanced in comparison to the properties of the random phases used to generate them. They also demonstrate that the spectral and correlation properties of such series are better, especially for short series, in comparison with standard white noise generators.
Stochastic models for the plastic rotation process in heat straightening of damaged steel plates
Authors: de Bejar Luis A. , Robinson Paul F. , Avent R. Richard
Published: May 2007

Two separate theoretical models are developed to predict the number of heat applications necessary to repair specified bends in damaged steel plates. One model is an application of the theory of reliability; this idealization is subsequently further simplified for practical engineering applications. The second is an application of the theory of stochastic processes: envisioning the record of plastic rotations obtained from the actual heat‐straightening of a subject plate as a finite portion of a member of the infinite ensemble of possible records for the repair, and assuming this process to be stationary and ergodic in the heat‐number domain, the theory of discrete spectral analysis is used to construct the power spectral density function of the process, and simulate artificial records. Then, simple statistical analysis allows the prediction with any desired degree of confidence. These independent probability‐based estimates successfully verify each other. As expected, the required number of repair heats for each test in the ensuing experimental program, under carefully controlled laboratory conditions, was consistently smaller than the corresponding theoretical prediction.
Job‐shop scheduling to minimize total waiting time
Authors: Chu Chengbin , Portmann Marie‐Claude
Published: May 2007

This paper addresses the job‐shop scheduling problem to minimize total waiting time. This also is equivalent to minimizing the work in process. Although, this problem is of relevance to manufacturing systems (Job‐shops), most of the work in the literature concerns the minimization of makespan for which the algorithms proposed are implicit enumeration procedures. For the minimization of total waiting time, to our knowledge, there are only empirical priority rules, all of which construct non‐delay schedules (i.e. there is no inserted idle time on the machines). In this work, we use theoretical results obtained for a single machine scheduling problem to construct an efficient heuristic for the problem at hand. This algorithm provides active schedules that are not always non‐delay schedules. The convergence and the complexity of the algorithm are discussed. The performance is also evaluated with respect to a classical priority rule.
The exploratory analysis of qualitative variables by means of three‐way analysis of two types of quantification matrices
Authors: Kiers Henk A. L.
Published: May 2007

A comparison is made between a number of techniques for the exploratory analysis of qualitative variables. The paper mainly focuses on a comparison between multiple correspondence analysis (MCA) and Gower's principal co‐ordinates analysis (PCO), applied to qualitative variables. The main difference between these methods is in how they deal with infrequent categories. It is demonstrated that MCA solutions can be dominated by infrequent categories, and that, especially in such cases, PCO is a useful alternative to MCA, because it tends to downweight the influence of infrequent categories. Apart from studying the difference between MCA and PCO, other alternatives for the analysis of qualitative variables are discussed, and compared to MCA and PCO.
A mean reverting process for pricing treasury bills and futures contracts
Authors: Morgan Ieuan G. , Neave Edwin H.
Published: May 2007

An analytically tractable, discrete‐time single‐factor model is developed for valuing treasury bills and futures contracts. It uses a multiplicative binomial foward process that creates neither negative nor implausibly large positive interest factors, and which can incorporate different possible degrees of mean reversion. The paper derives explicit formulae for bill prices, futures prices, their conditional variances and risk premia in a setting that relates the evolution of the term structure more closely to both model and data than do other similar works. In contrast to other term‐structure constrained models, this paper emphasizes that in a one‐factor model the martingale probabilities cannot be treated independently of the perturbation functions. The paper's empirical methods also differ from the customary approaches. Instead of comparing differences between model‐predicted and observed prices, the paper applies ARCH methodology to test model‐predicted ratios of conditional variances to risk premia. Our tests find influences exogenous to the model, but these factors do not seem capable of being explained with two‐factor models using only interest rates.
The nature and extent of the geographic market for hogs in the United States
Authors: Uri Noel D.
Published: May 2007

This paper looks at the question of whether hogs sold at different locations in the United States are part of a single geographic market covering the entire country. An answer to this question is sought using an approach to defining a geographic market based on the notion of instantaneous causality. The empirical results, based on prices for hogs at sixteen different locations over the period October 1989 to May 1992, suggest that there was but a single identifiable geographic market covering the entire United States. The implications of this finding are explored.
Information theory approach in efficiency measurement
Authors: Sengupta Jati K.
Published: May 2007

The current non–parametric method of measuring productive efficiency of input–output systems is generalized here in the stochastic case in terms of an information theory approach based on the concept of entropy. Use of maximum entropy as a method of finding the most probable distribution of the input–output data set and as a predictive criterion is illustrated for production systems with multiple inputs and outputs.
Bounds on stochastic convex allocation problems
Authors: Edirisinghe Chanaka , Atkins Derek , Iyogun Paul
Published: May 2007

We consider a stochastic convex program arising in a certain resource allocation problem. The uncertainty is in the demand for a resource which is to be allocated among several competing activities under convex inventory holding and shortage costs. The problem is cast as a two–period stochastic convex program and we derive tight upper and lower bounds to the problem using marginal distributions of the demands, which may be stochastically dependent. It turns out that these bounds are tighter than the usual bounds in the literature which are based on limited moment information of the underlying random variables. Numerical examples illustrate the bounds.
Non–parametric probability density function estimation on a bounded support: Applications to shape classification and speech coding
Authors: Saoudi S. , Hillion A. , Ghorbel F.
Published: May 2007

In statistics, it is usually difficult to estimate the probability density function from N independent samples X1,X2, …︁, XN identically distributed. A lot of work has been done in the statistical literature on the problem of probability density estimation (e.g. Cencov, 1962; Devroye and Gyorfi, 1981; Hall, 1980 and 1982; Hominal, 1979; Izenman, 1991; Kronmal and Tarter, 1968; Parzen, 1962; Rosenblatt, 1956). In this paper, we consider random variables on bounded support. Orthogonal series estimators, studied in detail by Kronmal and Tarter (1968), by Hall (1982) and by Cencov (1962), show that there is a disadvantage related to the Gibbs phenomenon on the bias of these estimators. We suggest a new method for the non–parametric probability density function estimation based on the kernel method using an appropriately chosen regular change of variable. The new method can be used for several problems of signal processing applications (scalar or vector quantization, speech or image processing, pattern recognition, etc.). Applications to shape classification and speech coding are given.
Behaviour of queueing approximations based on sample moments
Authors: Johnson Mary A. , Luhman Jennifer A.
Published: May 2007

We investigate moment–based queueing approximations in the presence of sampling error. Let L be the steady–state mean number in the system for a GI/M/1 queue. We focus on the estimation of L under the assumption that only sample moments of the interarrival–time distribution are known. A simulation experiment is carried out for several interarrival–time distributions. For each case, sample moments from the interarrival–time distribution are matched to an approximating phase–type distribution and the corresponding estimate L is obtained. We show that the sampling error in the moments induces bias as well as variability in L. Based on our simulation experiment, we suggest matching only two moments when the sample coefficient of variation is low or when sample size is low; otherwise, matching three moments is preferable.
A multivariate stochastic model with non‐stationary trend component
Authors: Kato Hiroko , Naniwa Sadao , Ishiguro Makio
Published: May 2007

The purposes of this paper are to introduce a multivariate non‐stationary stochastic time series model without individual detrending and to extract the multiple relationships between variables. To infer the statistical relation between variables, we attempt to estimate the co‐movement of multivariate non‐stationary time series components. The model is expressed in state‐space form, and time series components are estimated by the maximum likelihood method using numerical optimization algorithm. The Kalman filter algorithm is used to compute the likelihood of the model. The AIC procedure gives a criterion for selecting the best model fit for the data. The multiple relationship becomes clear by analysing estimated AR coefficients. Real economic data are used for a numerical example.
Semi‐parametric estimation of covariate effects using the positive stable frailty model
Authors: Wang S. T. , Klein John P. , Moeschberger M. L.
Published: May 2007

Many biological and medical studies have as a response of interest the time to occurrence of some event, such as the occurrence of a particular symptom or disease, remission, relapse, death due to some specific disease, or simply death. In this paper we study the problem of assessing the effect of potential risk factors on the outcome event of interest through a parametric or semi‐parametric frailty model where the lifetimes have a reason to be considered dependent. This dependence may arise because of multiple endpoints within the same individual or because, when studying a single endpoint, there are natural groupings between study subjects. The objective of this paper is to extend both parametric and semi‐parametric approaches to regression analysis in which the lifetimes of individuals in a group are effected by the same random frailty which follows a positive stable distribution. Some comparisons of the properties of this frailty distribution with other frailty distributions are made and an example which assesses the effect of a treatment in a litter‐matched tumorigenesis study is presented.
A time‐continuous markov chain interest model with applications to insurance
Authors: Norberg Ragnar
Published: May 2007

The force of interest is modelled by a homogeneous time‐continuous Markov chain with finite state space. Ordinary differential equations are obtained for expected values of various functionals of this process, in particular for moments of present values of payment streams that may be deterministic or, possibly, also stochastic and driven by a time‐continuous Markov chain. The homogeneity of the interest process gives rise to explicit formulae for expected values of some stationary functionals, e.g. moments of a perpetuity. Applications are made to some standard forms of insurance.
Harald cramér and insurance mathematics
Authors: Martin‐Löf Anders
Published: May 2007

A short history of the works of Harald Cramér in insurance mathematics is given. In particular, the early development of the collective risk theory starting with the works of F. Lundberg is outlined. Also, the so called zero point method for premium calculations invented by Cramér is described.
Joint test for functional forms and heteroscedasticity with property sales and valuation data
Authors: Wang Peijie
Published: May 2007

This paper proposes an approach to jointly testing functional forms and heteroscedasticity within the general Box‐Cox transformation framework. The approach is then applied to decide empirically the character of the residuals from regressions of properties' open market prices on their valuation.
Coadsorption‐Induced Reconstruction of Supramolecular Assembly Characteristics
Authors: Wu Dongxia , Deng Ke , He Meng , Zeng Qingdao , Wang Chen
Published: May 2007

A host supramolecular structure consisting of bis‐(2,2′:6′,2“‐terpyridine)‐4′‐oxyhexadecane (BT‐O‐C16) is shown to respond to coadsorbed molecules in dramatic ways, as observed by scanning tunneling microscopy (STM) on a highly oriented pyrolytic graphite (HOPG) surface under ambient conditions. Interestingly, the lattice parameter of the triphenylene‐filled complex differs significantly from that of the coronene‐filled one, although the triphenylene and coronene molecules are nearly the same size. The STM study and density functional theory calculations reveal that intermolecular hydrogen‐bond interactions play an essential role in forming the assembly structures. The different electronic properties of coronene and triphenylene molecules are responsible for the difference in lattice parameters and consequently for the difference in filling behaviors in the coronene/BT‐O‐C16 and triphenylene/BT‐O‐C16 binary systems.
AMPCS: Adaptive model predictive control scheduler for guaranteed delay in DiffServ architecture
Authors: Mahramian Mehran , Taheri Hassan , Haeri Mohammad
Published: May 2007

An increasing number of different applications face the challenge of providing end‐to‐end quality of service (QoS) support such as bandwidth, delay, jitter, and packet loss. In this paper, we have focused on DiffServ architecture to improve its accuracy. We proposed a new algorithm, called Adaptive Model Predictive Control Scheduler (AMPCS), to schedule differentiated buffers in routers, using Adaptive Model Predictive Control as the controller. AMPCS regulates the service rates of aggregated traffic classes dynamically in a way that some constraints on proportional delay or absolute delay can be guaranteed. Our contribution is to apply a model predictive controller to the scheduling problem to control the QoS parameters accurately. Simulation results show that the AMPCS performs acceptable QoS differentiations at core routers while it maintains end‐to‐end delay
constraints. Copyright © 2007 John Wiley & Sons, Ltd.
Satiety and test meal intake among women with binge eating disorder
Authors: Sysko Robyn , Devlin Michael J. , Walsh B. Timothy , Zimmerli Ellen , Kissileff Harry R.
Published: May 2007

Objective:

The purpose of the study was to measure test meal consumption and the changes in hunger and fullness during a test meal in obese individuals with and without binge eating disorder (BED) and normal‐weight controls.

Method:

Twelve women with BED, 12 obese control participants, and 12 normal‐weight control participants participated in two single‐item test meal sessions. In one session participants were instructed to “binge,” and the other eat a normal meal. Participants made ratings of hunger and fullness on visual analog scales after every 75‐g increment of food.

Results:

In comparison to obese or normal‐weight controls, patients with BED consumed significantly more food to reach a similar level of fullness or hunger.

Conclusion:

Individuals with BED consumed significantly more food and showed blunted changes in hunger and fullness during both the binge and nonbinge meals. These findings suggest that individuals with BED may have disturbances in satiety that in some ways resemble those described among individuals with bulimia nervosa. © 2007 by Wiley Periodicals, Inc.
Pathways utilized by dendritic cells for binding, uptake, processing and presentation of antigens derived from HIV‐1
Authors: Sabado Rachel L. , Babcock Ethan , Kavanagh Daniel G. , Tjomsland Veronica , Walker Bruce D. , Lifson Jeffrey D. , Bhardwaj Nina , Larsson Marie
Published: May 2007

The outcome following HIV infection depends on the nature and durability of the HIV‐specific T cell response induced initially. The activation of protective T cell responses depends upon dendritic cells (DC), antigen‐presenting cells which have the capacity to process and present viral antigens. DC pulsed with aldrithiol‐2‐inactivated HIV and delivered in vivo were reported to induce immune responses and promote virologic control in chronically HIV‐1‐infected subjects. To gain an understanding of this phenomenon, we characterized the steps involved in the presentation of antigens derived from aldrithiol‐2‐treated vs. infectious HIV‐1 by DC. Antigen presentation, on both MHC class I and II, was independent of DC‐specific ICAM‐3‐grabbing integrin, DEC‐205 and macrophage mannose receptor, C‐type lectins expressed by the DC. Inhibitor studies showed that presentation on MHC class I was dependent on viral fusion in a CD4/coreceptor‐dependent manner, both at the cell surface and within endosomes, and access to the classical endosomal processing pathway. MHC class II presentation of HIV‐associated antigens was dependent on active endocytosis, probably receptor‐mediated, and subsequent degradation of virions in acidified endosomes in the DC. Our study brings forth new facts regarding the binding, uptake, and processing of chemically inactivated virions leading to efficient antigen presentation and should aid in the design of more effective HIV vaccines.
Effect of Ligand Architecture on the Structure and Properties of Square‐Planar Nickel(II) Complexes of Amide‐Based Macrocycles
Authors: Sharma Savita K. , Upreti Shailesh , Gupta Rajeev
Published: May 2007

The present work discusses the design and synthesis of four novel macrocyclic ligands and their NiII complexes. All four ligands (H21EN, H22EN, H23OP, H24OP) are designed to provide an identical donor‐environment composed of two deprotonated anionic amide‐N coordination and two neutral amine‐N coordination and an identical 12‐membered macrocyclic ring around the nickel center. The NiII complexes (1, 2, 3, and 4 of doubly deprotonated ligands [1EN]2–, [2EN]2–, [3OP]2–, and [4OP]2–, respectively) are prepared and thoroughly characterized. The coordination geometry around the NiII center is square planar as determined by the single crystal structure analyses. The average Ni–Namide bond lengths are shorter by ca. 0.1 Å than the average Ni–Namine distances while the average Namide–Ni–Namide angles are shorter by ca. 4° than the average Namine–Ni–Namine angles. The NiII ion is housed quite tightly within the aperture of the macrocycle as seen by the short Ni–N bond lengths and a very small displacement (0.11–0.17 Å) of the Ni center out of the N4 basal plane. The detailed 1H and 13C NMR studies on the diamagnetic Ni–complexes reveal that the solid state conformation of the complexes 1–4 is retained in the solution. The NiIII/II potential is fairly positive (>0.6 V vs. SCE) for all four complexes, while the complexes with phenylene as part of the ligand also show the oxidation(s) of the ring(s) (>1.1 V vs. SCE). Coulometric measurements confirm both responses as 1e– process. Electrochemical or chemical oxidation at the 1st potential results in the generation of an unstable “green species” that show distinct features in the absorption spectrum and exhibit anisotropic EPR spectrum. These findings strongly point out that the unstable green species is a NiIII species. The 2nd and/or 3rd oxidation is centered on the phenylene ring(s) and lead to an immediate decomposition. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Mesoporous Carbon Prepared from Carbohydrate as Hard Template for Hierarchical Zeolites
Authors: Zhu Kake , Egeblad Kresten , Christensen Claus Hviid
Published: May 2007

A mesoporous carbon prepared from sucrose was successfully employed as a hard template to produce hierarchical silicalite‐1, thus providing a very simple and inexpensive route to desirable zeolite catalysts from widely available raw materials. The porous carbon was prepared by hydrothermal treatment of a mixture of sucrose and ammonia followed by carbonization of the mixture in N2 at high temperatures. The porous carbon produced by this method was subsequently applied as a hard template in the synthesis of mesoporous silicalite‐1 and removed by combustion after synthesis. X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected‐area electron diffraction (SAD), thermal gravimetry (TG), differential scanning calorimetry (DSC), N2 physisorption measurements, Hg porosimetry and CHN elemental analysis techniques were applied to investigate the porous carbon template as well as the mesoporous zeolite single‐crystal material. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Ten Years of a Biomimetic Approach to the Copper(II) Radical Site of Galactose Oxidase (Eur. J. Inorg. Chem. 17/2007)
Authors: Thomas Fabrice
Published: May 2007

The cover picture showsshows the active site of Galactose Oxidase, as it was crystallized in the middle of the 1990s. Its active form featured an unprecedented copper(II)‐tyrosyl (Tyr272·) radical system. Since 1996, several model compounds of this entity have been developed worldwide. They contributed significantly to the enhanced understanding of the spectral properties, structural attributes, and even to the reactivity of the enzyme's active site. Four prototypical complexes are shown; each of them is representative of the main classes of ligands developed (tripodal, salen, TACN, and iminosemiquinone scaffolds). Phenoxyl radicals typically exhibit absorption bands at around 420 and 600−800 nm, as shown in the UV/Vis spectrum. Ten years of this bioinorganic story is discussed in the Microreview by F. Thomas on p. 2379 ff.
Effect of Pinus radiata plantations on water balance in Chile
Authors: Huber Anton , Iroumé Andrés , Bathurst James
Published: May 2007

The effect of Pinus radiata (D. Don) plantations on water resources at different Chilean sites located between 33 and 40 south was determined. Incoming precipitation, canopy interception loss, evapotranspiration, net evapotranspiration (transpiration and evaporation from the soil), percolation and soil water content were measured in each site, where Pinus radiata plantations were 12 to 17 years old and between 700 and 830 trees ha−1 dense. The results were compared with those obtained from areas covered with perennial grasses and shrubs at the same sites. The pine canopies intercepted on average 36–40% of the annual rainfall at all sites where rainfall was less then 1200 mm, while only 15% of the mean rainfall was intercepted in the southernmost and rainy (2081 mm year−1) site. Annual net evapotranspiration increased from south to north from 32% of the incoming precipitation for the southernmost site to 55% for the one located at the lower latitude. In this northernmost site almost the entire incoming precipitation was evapotranspired. Annual percolation registered its minimum value in the northern site (5% of incoming precipitation) and its maxima in the southern one (53%). The values of net evapotranspiration and percolation were regulated by the pluviometric regime and the soil moisture retention capacity in each site. Compared with the shrub or grass covers, sites under Pinus radiata plantations registered higher water consumption by evapotranspiration and reduced percolation. Copyright © 2007 John Wiley & Sons, Ltd.
Characterization of groundwater quality in Kinmen Island using multivariate analysis and geochemical modelling
Authors: Liu Chen‐Wuing , Jang Cheng‐Shin , Chen Chan‐Po , Lin Chun‐Nan , Lou Kuo‐Liang
Published: May 2007

Kinmen is located in the south‐west of Mainland China and mainly has two islands, Large Kinmen and Leiyu. Residents in Kinmen have drunk groundwater over several decades. This work characterized the quality of groundwater in Kinmen using factor analysis (FA), cluster analysis (CA) and geochemical simulation. The factor scores were plotted spatially to illustrate the groundwater quality and were used to discuss the grouped relationship using CA. Salinization, redox and organic matter factors are identified from 17 hydrochemical measurements in 18 wells. Acidic and oxidizing groundwater with nitrate‐N pollution is distributed mainly in the west of Large Kinmen. Saline groundwater is distributed to the north‐east of Large Kinmen and in the south of Leiyu. Groundwater with organic matter is present throughout Leiyu. Five groups of the groundwater quality divided by CA can be interpreted according to one to three factors. The grouped characteristics of the groundwater quality help the local government and industries to plan the use and protection of groundwater resources. Furthermore, a geochemical simulation was used to demonstrate the formation processes of the acidic and oxidizing groundwater properties in granitic sediments. A large amount of the precipitation of the kaolinite and magnetite releases concentrations of hydrogen ion and raises the redox potential in the aquifers. Copyright © 2007 John Wiley & Sons, Ltd.
Epigenetic silencing of CDX2 is a feature of squamous esophageal cancer
Authors: Guo MingZhou , House Michael G. , Suzuki Hiromu , Ye Ying , Brock Malcolm V. , Lu Fengmin , Liu Zhihua , Rustgi Anil K. , Herman James G.
Published: May 2007

CDX2, a mammalian homologue of the homeobox gene ‘caudal,’ is expressed in gut epithelia and plays an important role in establishing the intestinal phenotype during development. Mice heterozygously disrupted for CDX2 develop disorganized polypoid hamartomas with glandular epithelium and stratified squamous metaplasia resembling foregut mucosa. Since no genetic disruptions of CDX2 have been reported to explain loss of gene function, we examined whether epigenetic mechanisms altered CDX2 expression. Eleven of 17 squamous esophageal cancer cell lines lacked expression of CDX2 that was restored following treatment with 5‐aza‐2′‐deoxycytidine, while all colorectal cancer cell lines expressed CDX2. Loss of expression was associated with DNA methylation in the 5′ region of CDX2 determined by methylation specific PCR and bisulfite sequencing. Methylation of CDX2 was rare in primary colorectal (1 of 44 tumors, 2%) and esophageal adenocarcinoma neoplasms (2 of 43 tumors, 5%), but was common in esophageal squamous carcinoma (24 of 45 tumors, 49%). No CDX2 methylation was found in normal tissues. Using semi‐quantitative RT‐PCR, expression of CDX2 was found in low level in normal esophagus, at higher levels in primary adenocarcinoma of the esophagus, but not in primary squamous cancers of the esophagus. Restoration of CDX2 in silenced cell lines resulted in expression of the CDX2 target gene MUC2, a gene important in glandular differentiation. Our results suggest that the inactivation of CDX2 in esophageal cancer associated with DNA methylation may be an important determinant of the squamous or non‐adenomatous phenotype. © 2007 Wiley‐Liss, Inc.
Malignant ascites protect against TRAIL‐induced apoptosis by activating the PI3K/Akt pathway in human ovarian carcinoma cells
Authors: Lane Denis , Robert Véronique , Grondin Roxanne , Rancourt Claudine , Piché Alain
Published: May 2007

Ascites are commonly found in ovarian cancer patients with advanced disease and are rich in cellular components and growth‐promoting factors. The purpose of this study was to assess the effect of malignant ascites on TRAIL‐induced apoptosis. We demonstrate that malignant ascites obtained from women with advanced ovarian cancer protect tumor cells from TRAIL‐ and FasL‐induced apoptosis but not against cisplatin‐induced apoptosis. This antiapoptotic effect was consistently found among different malignant ascites while nonmalignant peritoneal fluids or conditioned medium from TRAIL‐resistant cells failed to protect tumor cells against TRAIL killing. Malignant ascites strongly inhibits TRAIL‐induced caspase‐3 activation and PARP cleavage. Furthermore, ascites activate PI3K and its downstream target Akt and increases c‐FLIPS protein levels without affecting ERK phosphorylation status. The antiapoptotic effect of malignant ascites is abrogated by the inhibition of PI3K with LY294002, by a specific inhibitor of Akt and by Akt siRNA. We further show that the pro‐survival effect of ascites can be suppressed by down‐regulation of c‐FLIPS. Our data indicate that malignant effusions protect against TRAIL‐induced apoptosis by activating the PI3K/Akt pathway. These findings demonstrate that the tumor microenvironment may contribute to the resistance of ovarian cancer cells to death receptor‐induced apoptosis. © 2007 Wiley‐Liss, Inc.
CD40‐mediated death and cytokine secretion in colorectal cancer: A potential target for inflammatory tumour cell killing
Authors: Georgopoulos Nikolaos T. , Merrick Alison , Scott Nigel , Selby Peter J. , Melcher Alan , Trejdosiewicz Ludwik K.
Published: May 2007

CD40, a member of the tumour necrosis factor family, is expressed in a variety of epithelial cells. Although soluble CD40 agonists are growth‐inhibitory, membrane‐presented CD40 ligand (CD40L) induces extensive apoptosis in carcinoma cells. This study investigated whether CD40 is expressed in human colorectal carcinoma (CRC) cells and explored the functional consequences of CD40 ligation. CD40 expression in a panel of CRC lines was assessed by flow cytometry and in resected human CRCs by immunohistochemistry. CRC cells were treated in vitro with soluble CD40 agonists or cocultured with fibroblasts expressing membrane‐bound CD40 ligand. Apoptosis was determined by flow cytometry using Annexin V/propidium iodide labelling and by a DNA fragmentation assay. Cytokine secretion induced by CD40 ligation was quantified by a multiplex‐bead array approach. We show that CD40 is expressed in a proportion of established CRC lines in culture and that receptor expression is functional. Activation of CD40 by membrane‐presented CD40L, but not soluble agonists, causes high levels of death in CD40‐positive CRC cells and induces secretion of proinflammatory cytokines. In agreement with our in vitro observations, immunohistochemical studies demonstrated that CD40 is highly expressed in a proportion of colorectal cancer specimens. The high level of susceptibility of CRC cells to CD40‐killing combined with the ability of CD40 to induce concomitant secretion of proinflammatory cytokines suggest that CD40 ligation may represent a novel mechanism for elimination of CRC cells and render CD40 a promising therapeutic target for the eradication of colorectal tumours. © 2007 Wiley‐Liss, Inc.
Pancreatic cancer microenvironment
Authors: Kleeff Jörg , Beckhove Philipp , Esposito Irene , Herzig Stephan , Huber Peter E. , Löhr J. Matthias , Friess Helmut
Published: May 2007

Pancreatic ductal adenocarcinoma remains an extremely aggressive malignancy that is virtually therapy‐resistant and has therefore one of the worst prognoses of all human cancers. The focus of research, which had been placed mostly on genetic and epigenetic alterations of the cancer cells themselves, has shifted gradually towards the microenvironment. The cancer microenvironment consists of various components, including fibroblasts, endothelial cells, immune cells, and endocrine cells, that interact with each other and the cancer cells in a complex fashion. This interplay has implications for pancreatic cancer cell growth, migration and invasion, angiogenesis, and immunological recognition of cancer cells. Evidence is accumulating that the cancer microenvironment plays an active role in disease progression, and efforts are being made to target this interplay between cancer cells and host cells to improve the outcome of this deadly disease. © 2007 Wiley‐Liss, Inc.
More proofs of menger's theorem
Authors: Nash‐Williams C. St. J. A. , Tutte W. T.
Published: May 2007

Four ways of proving Menger's Theorem by induction are described. Two of them involve showing that the theorem holds for a finite undirected graph G if it holds for the graphs obtained from G by deleting and contracting the same edge. The other two prove the directed version of Menger's Theorem to be true for a finite digraph D if it is true for a digraph obtained by deleting an edge from D.
Some recent results in hamiltonian graphs
Authors: Lesniak‐Foster L.
Published: May 2007

A variety of recent developments in hamiltonian theory are reviewed. In particular, several sufficient conditions for a graph to be hamiltonian, certain hamiltonian properties of line graphs, and various hamiltonian properties of powers of graphs are discussed. Furthermore, the concept of an n‐distant hamiltonian graph is introduced and several theorems involving this special class of hamiltonian graphs are presented.
Blocks and the nonorientable genus of graphs
Authors: Stahl Saul , Beineke Lowell W.
Published: May 2007

Examples are given to show that the nonorientable genus of a graph is not additive over its blocks. A nonorientable analog for the Battle, Harary, Kodama, and Youngs Theorem is proved; this completely determines the nonorientable genus of a graph in terms of its blocks. It is also shown that one of the above counterexamples has the minimum possible order.
Packing and covering constants for certain families of trees. I
Authors: Meir A. , Moon J. W.
Published: May 2007

If ℱ denotes a family of rooted trees, let pk(n) and ck(n) denote the average value of the k‐packing and k‐covering numbers of trees in ℱ that have n nodes. We assume, among other things, that the generating function y of trees in ℱ satisfies a relation of the type y = xϕ(y) for some power series ϕ. We show that the limits of pk(n)/n and ck(n)/n as n → ∞ exist and we describe how to evaluate these limits.
Computer reconstruction of small graphs
Authors: McKay B. D.
Published: May 2007

The Reconstruction Conjecture is established for graphs with nine vertices.
The number of self‐complementary achiral necklaces
Authors: Palmer E. M. , Schwenk A. J.
Published: May 2007

Necklaces with beads of two colors which are left unchanged both by a reflection as well as by the interchange of the two colors are characterized in terms of their axes of symmetry. This characterization is then used to enumerate them. For n = 2rm with r ≥ 1 and m odd, the number of self‐complementary achiral necklaces is magnified image for large even n, this sum is asymptotic to 2{n/4}‐1.
Bounds on chromatic numbers of multiple factors of a complete graph
Authors: Plesník Ján
Published: May 2007

Bounds on the sum and product of the chromatic numbers of n factors of a complete graph of order p are shown to exist. The well‐known theorem of Nordhaus and Gaddum solves the problem for n = 2. Strict lower and some upper bounds for any n and strict upper bounds for n = 3 are given. In particular, the sum of the chromatic numbers of three factors is between 3p1/3 and p + 3 and the product is between p and [(p + 3)/3]3.
Graphs with unique maximal clumpings
Authors: Blass Andreas
Published: May 2007

A partition of the vertices of a graph is called a clumping if, for vertices in distinct partition classes, adjacency depends only on the partition classes, not on the specific vertices. We give a simple necessary and sufficient condition for a finite graph to have a unique maximal clumping. We also investigate the extent to which this and related results generalize to infinite graphs.
Generalized Embedding Schemes
Authors: Stahl Saul
Published: May 2007

Covering projections are used to provide a logical foundation for the generalized embedding schemes which describe embeddings of graphs on closed surfaces that are not necessarily orientable. Criteria are provided to resolve the question of when such schemes describe the same embedding, and when that embedding is orientable. The schemes are then applied to derive some interpolation‐type theorems for embeddings on closed surfaces.
The genus of the n‐octahedron: Regular cases
Authors: Jungerman Mark , Ringel Gerhard
Published: May 2007

The n‐octahedron On, also denoted K(2,2, …, 2) or Kn(2), is the complete n‐partite graph with two vertices in each partite set. The formula

for the (orientable) genus of On is conjectured for all n and proved for n ≠ (mof 3). Triangular embeddigns are possible precisely when n ≠ 2 (mod 3), and the formula is established by exhibiting such embeddings.
A bibliographic survey of edge‐colorings
Authors: Fiorini S.
Published: May 2007

This paper presents a bibliography on edge‐colorings of graphs which is as complete as possible to date. We introduce the papers by a brief discussion of the ideas involved.
A class of Hamiltonian regular graphs
Authors: Erdös Paul , Hobbs Arthur M.
Published: May 2007

In this paper, we show that n ⩾ 4 and if G is a 2‐connected graph with 2n or 2n−1 vertices which is regular of degree n−2, then G is Hamiltonian if and only if G is not the Petersen graph.
Centers to centroids in graphs
Authors: Slater Peter J.
Published: May 2007

For S ⊆ V(G) the S‐center and S‐centroid of G are defined as the collection of vertices u ∈ V(G) that minimize es(u) = max {d(u, v): v ∈ S} and ds(u) = ∑u∈S d(u, v), respectively. This generalizes the standard definition of center and centroid from the special case of S = V(G). For 1 ⩽ k ⩽|V(G)| and u ∈ V(G) let rk(u) = max {∑s∈S d(u, s): S ⊆ V(G), |S| = k}. The k‐centrum of G, denoted C(G; k), is defined to be the subset of vertices u in G for which rk(u) is a minimum. This also generalizes the standard definitions of center and centroid since C(G; 1) is the center and C(G; |V(G)|) is the centroid. In this paper the structure of these sets for trees is examined. Generalizations of theorems of Jordan and Zelinka are included.
Current graphs and bi‐embeddings
Authors: Anderson I. , White A. T.
Published: May 2007

Let N(γ,γ′) denote the size of the smallest complete graph which cannot be edge‐partitioned into two parts embeddable in closed orientable surfaces of genera γ,γ′ respectively. The theory of current graphs is used to determine the values of N(γ,γ′) in certain cases. Some related block designs are discussed.
Degree frequencies in digraphs and tournaments
Authors: Alspach Brian , Reid K. B.
Published: May 2007

The number of vertices in a digraph G having a particular outdegree (indegree) is called the frequency of the outdegree (indegree). A set F of distinct positive integers {f1, f2, …, fn} is the frequency set of the digraph G if every outdegree and indegree occurs with frequency fj∈F and for each fj∈F there is a least one outdegree and at least one indegree with frequency fj. We prove that each nonempty set F of positive integers is the frequency set of some tournament, and we determine the smallest possible order for such a tournament. Similar results for asymmetric digraphs are also given. The results and techniques for frequency sets are used to derive corresponding results for vertex frequency partitions.
On supercompact graphs
Authors: Lim Chong‐Keang
Published: May 2007

A graph G is called a supercompact graph if G is the intersection graph of some family 𝒯 of subsets of a set X such that 𝒯 satisfies the Helly property and for any x≠y in X, there exists S ∈ 𝒯 with x ∈ S, y ∉ S. Various characterizations of supercompact graphs are given. It is shown that every clique‐critical graph is supercompact. Furthermore, for any finite graph, H, there is at most a finite number of different supercompact graphs G such that H is the clique‐graph of G.
Fixed‐edge theorem for graphs with loops
Authors: Nowakowski Richard , Rival Ivan
Published: May 2007

Let G be an undirected graph without multiple edges and with a loop at every vertex—the set of edges of G corresponds to a reflexive and symmetric binary relation on its set of vertices. Then every edge‐preserving map of the set of vertices of G to itself fixes an edge [{f(a), f(b)} = {a, b} for some edge (a, b) of G] if and only if (i) G is connected, (ii) G contains no cycles, and (iii) G contains no infinte paths. The proof is conerned with those subgraphs H of a graph G for which there is an edge‐preserving map f of the set of vertices of G onto the set of vertices of H and satisfying f(a) = a for each vertex a of H.
Graphs with prescribed connectivity and line graph connectivity
Authors: Bauer Douglas , Tindell Ralph
Published: May 2007

Chartrand and Stewart have shown that the line graph of an n‐connected graph is itself n‐connected. This paper shows that for every pair of integers m > n > 1 there is a graph of point connectivity n whose line graph has point connectivity m. The corresponding question for line connectivity is also resolved.
Theorem on directed graphs, applicable to logic
Authors: Shoesmith D. J. , Smiley T. J.
Published: May 2007

A semicycle is said to turn at a point a if the arcs incident to a are both to it or both from it. We prove that if a nonempty set of points of a finite directed graph contains a turning point of each semicycle, then one of its members is a turning point of every semicycle to which it belongs; and we indicate the application of this result to mathematical logic through the modeling of arguments by graphs.
Spectral criterion for cycle balance in networks
Authors: Acharya B. Devadas
Published: May 2007

A network is cycle balanced if the product of the weights (nonzero real numbers) of the lines of every cycle in it is positive. In this paper, we prove that a network D is cycle balanced if and only if its adjacency matrix is isospectral with its nonnegative counterpart. Consequent to this theorem is an analogous criterion for structural balance in sigraphs (abbreviation for “signed graphs”) as also for cycle balance in signed digraphs. These criteria establish in a natural way a wide scope for cospectrality considerations in the classes of signed digraphs and sigraphs.