bluuebunny/crossref_metadata_2025 huggingface dataset:
Approximate versions of Melamed's theorem
Authors: Barbour A. D. , Brown Timothy C.
Published: April 2006

In 1979, Melamed proved that, in an open migration process, the absence of ‘loops' is necessary and sufficient for the equilibrium flow along a link to be a Poisson process. In this paper, we prove approximation theorems with the same flavour: the difference between the equilibrium flow along a link and a Poisson process with the same rate is bounded in terms of expected numbers of loops. The proofs are based on Stein's method, as adapted for bounds on the distance of the distribution of a point process from a Poisson process in Barbour and Brown (1992b). Three different distances are considered, and illustrated with an example consisting of a system of tandem queues with feedback. The upper bound on the total variation distance of the process grows linearly with time, and a lower bound shows that this can be the correct order of approximation.
A modified block replacement policy with two variables and general random minimal repair cost
Authors: Sheu Shey-Huei
Published: April 2006

This paper considers a modified block replacement with two variables and general random minimal repair cost. Under such a policy, an operating system is preventively replaced by new ones at timeskT(k=1, 2, ···) independently of its failure history. If the system fails in [(k − 1)T,(k− 1)T+T0) it is either replaced by a new one or minimally repaired, and if in [(k− 1)T+T0, kT) it is either minimally repaired or remains inactive until the next planned replacement. The choice of these two possible actions is based on some random mechanism which is age-dependent. The cost of theith minimal repair of the system at ageydepends on the random partC(y) and the deterministic partci(y). The expected cost rate is obtained, using the results of renewal reward theory. The model with two variables is transformed into a model with one variable and the optimum policy is discussed.
Average case behavior of random search for the maximum
Authors: Calvin James M. , Glynn Peter W.
Published: April 2006

This paper is a study of the error in approximating the global maximum of a Brownian motion on the unit interval by observing the value at randomly chosen points. One point of view is to look at the error from random sampling for a given fixed Brownian sample path; another is to look at the error with both the path and observations random. In the first case we show that for almost all Brownian paths the error, normalized by multiplying by the square root of the number of observations, does not converge in distribution, while in the second case the normalized error does converge in distribution. We derive the limiting distribution of the normalized error averaged over all paths.
Ruin probabilities via local adjustment coefficients
Authors: Asmussen Søren , Nielsen Hanne Mandrup
Published: April 2006

Let ψ(u) be the ruin probability in a risk process with initial reserve u, Poisson arrival rate β, claim size distribution B and premium rate p(x) at level x of the reserve. Let y(x) be the non-zero solution of the local Lundberg equation . It is shown that is non-decreasing and that log ψ(u) ≈ –I(u) in a slow Markov walk limit. Though the results and conditions are of large deviations type, the proofs are elementary and utilize piecewise comparisons with standard risk processes with a constant p. Also simulation via importance sampling using local exponential change of measure defined in terms of the γ(x) is discussed and some numerical results are presented.
Convergence to stationary state for a Markov move-to-front scheme
Authors: Rodrigues Eliane R.
Published: April 2006

This work considersitems (e.g. books, files) arranged in an array (e.g. shelf, tape) withNpositions and assumes that items are requested according to a Markov chain (possibly, of higher order). After use, the requested item is returned to the leftmost position of the array. Successive applications of the procedure above give rise to a Markov chain on permutations. For equally likely items, the number of requests that makes this Markov chain close to its stationary state is estimated. To achieve that, a coupling argument and the total variation distance are used. Finally, for non-equally likely items and so-calledp-correlated requests, the coupling time is presented as a function of the coupling time when requests are independent.
Some general characteristics of two-state reliability models for maintained systems
Authors: Marlow Norman A. , Tortorella Michael
Published: April 2006

Formulas for the asymptotic failure rate, long-term average availability, and the limiting distribution of the number of long ‘outages' are obtained for a general class of two-state reliability models for maintained systems. The results extend known formulas for alternating renewal processes to a wider class of point processes that includes sequences of dependent or non-identically distributed operating and repair times.
Max-infinite divisibility and multivariate total positivity
Authors: Alzaid Abdulhamid A. , Proschan Frank
Published: April 2006

The concept of max-infinite divisibility is viewed as a positive dependence concept. It is shown that every max-infinitely divisible distribution function is a multivariate totally positive function of order 2 (MTP2). Inequalities are derived, with emphasis on exchangeable distributions. Applications and examples are given throughout the paper.
TheM/M/1 queue with mass exodus and mass arrivals when empty
Authors: Chen Anyue , Renshaw Eric
Published: April 2006

AnM/M/1 queue is subject to mass exodus at rateβand mass immigration at ratewhen idle. A general resolvent approach is used to derive occupation probabilities and high-order moments. This powerful technique is not only considerably easier to apply than a standard direct attack on the forward p.g.f. equation, but it also implicitly yields necessary and sufficient conditions for recurrence, positive recurrence and transience.
The rate of occurrence of failures
Authors: Yeh Lam
Published: April 2006

In this article, we assume that the state of a system forms a continuous-time Markov chain or a higher-dimensional Markov process after introducing some supplementary variables. A formula for evaluating the rate of occurrence of failures for the system is derived. As an application of the theory, a maintenance model for a two-component system is also studied.
On crossing times for multidimensional walks with skip-free components
Authors: Borovkov K. A.
Published: April 2006

The paper deals with processes in(or), one of whose components is skip-free. We obtain identities for distributions of hitting times for the components of the process generalizing the well-known one for the one-dimensional case. These relations reflect the fact that in this case spatial and time coordinates play, in some sense, symmetric roles. They turn out to be useful for solving several problems. For example, they allow us to find the distribution of the number of jumps of the process, which fall in a fixed set before the skip-free component of the process hits a fixed level. Examples are given showing how our results can be applied to models in branching processes, queueing, and risk theory.
Probability bounds on the finite sum of the binary sequence of orderk
Authors: Dhar Sunil K. , Jiang Xulun
Published: April 2006

The cumulative distribution of the finite sum of the binary sequence of orderkis studied and some of its applications discussed. Certain properties of this sequence are investigated and uniformly superior bounds for the cumulative distribution under minimal information on the ‘success' probabilities are derived.
Brownian motions on shape and size-and-shape spaces
Authors: Le Huiling
Published: April 2006

The diffusions on the shape and size-and-shape spaces induced by brownian motions on the pre-size-and-shape spaces have been investigated in several papers (cf.). We here address the dual problem: the character of the diffusions on the pre-shape and pre-size-and-shape spaces which induce brownian motions on the shape and size-and-shape spaces. In particular we show that the shape and size-and-shape spaces for k labelled points in ℝm are stochastically complete if k > m and obtain the heat kernels of certain diffusions which induce brownian motions on the size-and-shape spaces.
Expansions for Markov-modulated systems and approximations of ruin probability
Authors: Błaszczyszyn Bartłomiej , Rolski Tomasz
Published: April 2006

LetNbe a stationary Markov-modulated marked point process on ℝ with intensityβ∗and consider a real-valued functionalψ(N). In this paper we study expansions of the formEψ(N) =a0+β∗a1+ ·· ·+ (β∗)nan+o((β∗)n) forβ∗→ 0. Formulas for the coefficientsaiare derived in terms of factorial moment measures ofN. We computea1anda2for the probability of ruinφuwith initial capitalufor the risk process in the Markov-modulated environment;a0= 0. Moreover, we give a sufficient condition forϕuto be an analytic function ofβ∗. We allow the premium rate functionp(x) to depend on the actual risk reserve.
Bonferroni inequalities and deviations of discrete distributions
Authors: Móri Tamás F.
Published: April 2006

In the paper we first show how to convert a generalized Bonferroni-type inequality into an estimation for the generating function of the number of occurring events, then we give estimates for the deviation of two discrete probability distributions in terms of the maximum distance between their generating functions over the interval [0, 1].
First passage time distribution of a Wiener process with drift concerning two elastic barriers
Authors: Dominé Marco
Published: April 2006

We solve the Fokker-Planck equation for the Wiener process with drift in the presence of elastic boundaries and a fixed start point. An explicit expression is obtained for the first passage density. The cases with pure absorbing and/or reflecting barriers arise for a special choice of a parameter constellation. These special cases are compared with results in Darling and Siegert [5] and Sweet and Hardin [15].
A heterogeneous blocking system in a random environment
Authors: Falin G.
Published: April 2006

We obtain a necessary and sufficient condition for the interaction between a service system and an external environment under which the stationary joint distribution of the set of busy channels and the state of the external environment is given by a product-form formula.
Geometric Markov chains
Authors: Rising William
Published: April 2006

A generalization of the familiar birth–death chain, called the geometric chain, is introduced and explored. By the introduction of two families of parameters in addition to the infinitesimal birth and death rates, the geometric chain allows transitions beyond the nearest neighbor, but is shown to retain the simple computational formulas of the birth–death chain for the stationary distribution and the expected first-passage times between states. It is also demonstrated that even when not reversible, a reversed geometric chain is again a geometric chain.
Runs on a circle
Authors: Koutras M. V. , Papadopoulos G. K. , Papastavridis S. G.
Published: April 2006

In the present paper we study the number of occurrences of non-overlapping success runs of lengthin a sequence of (not necessarily identical) Bernoulli trials arranged on a circle. An exact formula is given for the probability function, along with some sharp bounds which turn out to be very useful in establishing limiting (Poisson convergence) results. Certain applications to statistical run tests and reliability theory are also discussed.
Product forms based on backward traffic equations
Authors: Boucherie Richard J.
Published: April 2006

This paper introduces a new form of local balance and the corresponding product-form results. It is shown that these new product-form results allow capacity constraints at the stations of a queueing network without reversibility assumptions and without special blocking protocols. In particular, exact product-form results for heavily loaded queueing networks are obtained.
The general correlated random walk
Authors: Chen Anyue , Renshaw Eric
Published: April 2006

In this paper we provide further results on the generald-dimensional correlated random walk. In particular, we prove that then-step characteristic function of any correlated random walk satisfies a recurrence formula which enables both it and the total characteristic function to be obtained. Some examples are then considered.
Exponential upper bounds via martingales for multiplexers with Markovian arrivals
Authors: Buffet E. , Duffield N. G.
Published: April 2006

We obtain explicit upper bounds in closed form for the queue length in a slotted time FCFS queue in which the service requirement is a sum of independent Markov processes on the state space {0, 1}, with integral service rate. The bound is of the form[queue lengthfor anywherec< 1 andy> 1 are given explicitly in terms of the parameters of the model. The model can be viewed as an approximation for the burst-level component of the queue in an ATM multiplexer. We obtain heavy traffic bounds for the mean queue length and show that for typical parameters this far exceeds the mean queue length for independent arrivals at the same load. We compare our results on the mean queue length with an analytic expression for the case of unit service rate, and compare our results on the full distribution with computer simulations.
Limit theorems and estimation theory for branching processes with an increasing random number of ancestors
Authors: Dion J. P. , Yanev N. M.
Published: April 2006

This paper deals with a Bienaymé-Galton-Watson process having a random number of ancestors. Its asymptotic properties are studied when both the number of ancestors and the number of generations tend to infinity. This yields consistent and asymptotically normal estimators of the mean and the offspring distribution of the process. By exhibiting a connection with the BGW process with immigration, all results can be transported to the immigration case, under an appropriate sampling scheme. A key feature of independent interest is a new limit theorem for sums of a random number of random variables, which extends the Gnedenko and Fahim (1969) transfer theorem.
Orthogonal representations of random fields and an application to geophysics data
Authors: Ruiz-Medina M. D. , Valderrama M. J.
Published: April 2006

We present a brief summary of some results related to deriving orthogonal representations of second-order random fields and its application in solving linear prediction problems. In the homogeneous and/or isotropic case, the spectral theory provides an orthogonal expansion in terms of spherical harmonics, called spectral decomposition (Yadrenko 1983). A prediction formula based on this orthogonal representation is shown. Finally, an application of this formula in solving a real-data problem related to prospective geophysics techniques is presented.
A Highly Sensitive Hybrid Colorimetric and Fluorometric Molecular Probe for Cyanide Sensing Based on a Subphthalocyanine Dye
Authors: Palomares E. , Martínez‐Díaz M. V. , Torres T. , Coronado E.
Published: April 2006

A highly sensitive, selective colorimetric and fluorometric molecular probe based on a subphthalocyanine dye has been developed for cyanide‐anion determination in aqueous solution. It has also been shown that a carboxysubphthalocyanine derivative can be covalently anchored to transparent mesoporous nanocrystalline high‐surface‐area metal oxide films to detect low concentrations of cyanide anion in pure water with no interference from other anionic or cationic species.
Growing Metal Nanoparticles by Enzymes
Authors: Willner I. , Baron R. , Willner B.
Published: April 2006

Enzymes act as catalysts for the growth of metallic nanoparticles (NPs). The enzyme‐mediated growth of metallic NPs provides a general means to follow biocatalyzed transformations, and to develop optical sensors for different substrates such as glucose, L‐DOPA, alcohols, lactate or nerve gas analogs. Enzymes modified with Au NPs act as biocatalysts for the fabrication of metallic nanowires. The dip‐pen nanolithography of NP‐functionalized enzymes on Si surfaces yields biocatalytic templates that enable the orthogonal evolution of nanowires consisting of different metals.
New unbiased symmetric metrics for evaluation of air quality models
Authors: Yu Shaocai , Eder Brian , Dennis Robin , Chu Shao‐Hang , Schwartz Stephen E.
Published: April 2006

Unbiased symmetric metrics to quantify the relative bias and error between modeled and observed concentrations, based on the factor between measured and observed concentrations, are introduced and compared to conventionally employed metrics. Application to the evaluation of several data sets shows that the new metrics overcome concerns with the conventional metrics and provide useful measures of model performance. Copyright © 2006 Royal Meteorological Society
Chirality as an inherent general property of matter
Authors: Davankov Vadim
Published: April 2006

A statement has been formulated that chirality is an indispensable inherent property of all material objects, at one level of organization of matter or another. The translation of chirality from one level of material objects to another deserves our attention. The parity violation of weak interactions can be discussed in terms of the homochirality of the pool of fundamental particles, as it translates into optical activity of metal vapors. Individual photons and energy quanta are considered to be chiral entities, too, since they can be separated into beams of circularly polarized radiation. The chiral structure of the universe has been proposed and a method of determining the orientation of the axis of rotation of the universe suggested. Chirality 18:459–461, 2006. © 2006 Wiley‐Liss, Inc.
Synthesis, chiral HPLC resolution and configuration assignment of 1‐phenylglyceryl trinitrate stereomers
Authors: Chegaev Konstantin , Lazzarato Loretta , Tron Gian Cesare , Marabello Domenica , Stilo Antonella Di , Cena Clara , Fruttero Roberta , Gasco Alberto , Vanthuyne Nicolas , Roussel Christian
Published: April 2006

As an introductory study of in vitro vasodilating activity, the access to the four stereomers of 1‐phenylglyceryl trinitrate is described using achiral and chiral chromatography. For semi‐preparative separation of the enantiomers, a Chiralcel OD (250 × 10 mm, 10 μm) was used. Catalytic reduction leading to the corresponding stereomers of 1‐phenylglycerol allowed absolute configuration assignments. The same methods were used for the separation and configuration assignment of the enantiomers of 3‐phenylpropane‐1,2‐diyl dinitrate. Chirality, 2006. © 2006 Wiley‐Liss, Inc.
Restriction landmark genome scanning method using isoschizomers (MspI/HpaII) for DNA methylation analysis
Authors: Takamiya Tomoko , Hosobuchi Saeko , Asai Kenji , Nakamura Eiji , Tomioka Keisuke , Kawase Makoto , Kakutani Tetsuji , Paterson Andrew H. , Murakami Yasufumi , Okuizumi Hisato
Published: April 2006

Restriction landmark genome scanning (RLGS) is a 2‐DE of genomic DNA, which visualizes thousands of loci. In a conventional RLGS method for methylation analysis, we have used a methylation sensitive restriction enzyme, NotI as a landmark. However, it was unable to discriminate methylation polymorphism from sequence polymorphism. Here, we report an improved RLGS method to detect methylated sites directly. We employed isoschizomers, MspI and HpaII, that recognize the same sequence (CCGG) but have different methylation sensitivity. We carried out the RLGS analysis of Arabidopsis thaliana ecotype Columbia, and obtained a pair of spot patterns with MspI and HpaII. We detected 22 spots in both patterns. In comparison of them, 18% of the spots were polymorphic, which indicated the methylation of C5mCGG sites. Further analyses revealed an additional methylated site of NotI. Moreover, 52 and 54 restriction enzyme sites were also analyzed in two other ecotypes, Wassilewskija and Landsberg erecta, respectively. Consequently, 15% of the 52 common sites showed methylation polymorphism among the three ecotypes. The restriction sites analyzed in this study were located in or near genes, and contribute new data about the correlation between methylation status and gene expression. Therefore, this result strongly indicates that the improved RLGS method is readily applicable to practical analyses of methylation dynamics, and provides clues to the relationship between methylation and gene expression.
Demographics and motives affecting faculty retirement
Authors: Conley Valerie Martin
Published: April 2006

Late‐career decisions are made by faculty who vary widely in career achievement, personal circumstances, and now, retirement patterns.
Simulation of groundwater dynamics in the North China Plain by coupled hydrology and agricultural models
Authors: Nakayama Tadanobu , Yang Yonghui , Watanabe Masataka , Zhang Xiying
Published: April 2006

We simulated the effects of irrigation on groundwater flow dynamics in the North China Plain by coupling the NIES Integrated Catchment‐based Ecohydrology (NICE) model with DSSAT‐wheat and DSSAT‐maize, two agricultural models. This combined model (NICE‐AGR) was applied to the Hai River catchment and the lower reach of the Yellow River (530 km wide by 840 km long) at a resolution of 5 km. It reproduced excellently the soil moisture, evapotranspiration and crop production of summer maize and winter wheat, correctly estimating crop water use. So, the spatial distribution of crop water use was reasonably estimated at daily steps in the simulation area. In particular, NICE‐AGR reproduced groundwater levels better than the use of statistical water use data. This indicates that NICE‐AGR does not need detailed statistical data on water use, making it very powerful for evaluating and estimating the water dynamics of catchments with little statistical data on seasonal water use. Furthermore, the simulation reproduced the spatial distribution of groundwater level in 1987 and 1988 in the Hebei Plain, showing a major reduction of groundwater level due mainly to overpumping for irrigation. Copyright © 2006 John Wiley & Sons, Ltd.
Effectiveness of three post‐fire rehabilitation treatments in the Colorado Front Range
Authors: Wagenbrenner J. W. , MacDonald L. H. , Rough D.
Published: April 2006

Post‐fire rehabilitation treatments are commonly implemented after high‐severity wildfires, but few data are available about the efficacy of these treatments. This study assessed post‐fire erosion rates and the effectiveness of seeding, straw mulching, and contour felling in reducing erosion after a June 2000 wildfire northwest of Loveland, Colorado. Site characteristics and sediment yields were measured on 12 burned and untreated control plots and 22 burned and treated plots from 2000 to 2003. The size of the hillslope plots ranged from 0·015 to 0·86 ha.

Sediment yields varied significantly by treatment and were most closely correlated with the amount of ground cover. On the control plots the mean sediment yield declined from 6–10 Mg ha−1in the first two years after burning to 1·2 Mg ha−1in 2002 and 0·7 Mg ha−1in 2003. Natural regrowth caused the amount of ground cover on the control plots to increase progressively from 33% in fall 2000 to 88% in fall 2003. Seeding had no effect on either the amount of ground cover or sediment yields. Mulching reduced sediment yields by at least 95% relative to the control plots in 2001, 2002, and 2003, and the lower sediment yields are attributed to an immediate increase in the amount of ground cover in the mulched plots. The contour‐felling treatments varied considerably in the quality of installation, and sediment storage capacities ranged from 7 to 32 m3ha−1. The initial contour‐felling treatment did not reduce sediment yields when subjected to a very large storm event, but sediment yields were significantly reduced by a contour‐felling treatment installed after this large storm. The results indicate that contour felling may be able to store much of the sediment generated in an average year, but will not reduce sediment yields from larger storms. Copyright © 2006 John Wiley & Sons, Ltd.
Cytotoxicity and altered c‐myc gene expression by medical polyacrylamide hydrogel
Authors: Xi T.F. , Fan C.X. , Feng X.M. , Wan Z.Y. , Wang C.R. , Chou L.L.
Published: April 2006

Medical Polyacrylamide Hydrogel (PAMG)has been used in plastic and aesthetic surgery for years. However, its safety is still in doubt in many countries. In the current research, first an approach, using high performance liquid chromatography (HPLC), to determine the amount of residual acrylamide monomer (AM) in the PAMG was presented. Then the cytotoxicity of PAMG was investigated using cell counting and methyl thiazolyl tetrazolium (MTT) assay. To explore the mechanism of this toxicity, normal human fibroblasts cultured in medium extracts were analyzed. Membrane changes and other related parameters were investigated using flow cytometry (FCM). Real time fluorescent polymerase chain reaction (real time PCR) was also introduced to determine the biological response of the fibroblasts. During this process, three representative genes (p53, β‐actin, and c‐myc, which are tumor suppressor genes, housekeeping genes, and proto‐oncogenes respectively) were selected for examination. Results indicated that a method based on HPLC is practical and simple for determining AM in PAMG. The detection limits can reach the desired ppb level, and so it can fully meet the requirements of the studies of PAMG. Polyacylamide Hydrogel inhibits the growth of human fibroblasts and may cause the apoptosis of human fibroblasts. Moreover, it can alter physical parameters such as the size and the granularity of these cells. Furthermore, these three genes have a relatively typical amplification plot and highly related, wide‐range standard curves, and so this reaction system is definitely suitable for the semiquantification of these genes. PAMG induces the increase of the message ribonucleic acid (mRNA) expression of c‐myc, while the p53 and β‐actin remain even. This change is not related to the concentration of AM in the gel and may be incited by other components in the extract of PMAG. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Use of polylactic acid/polytrimethylene carbonate blends membrane to prevent postoperative adhesions
Authors: Qin Yuyue , Yuan Minglong , Li Lin , Guo Siyuan , Yuan Mingwei , Li Wei , Xue Jing
Published: April 2006

The objective of the study was to evaluate the effect of a novel biodegradable membrane on the prevention of postoperative adhesion formation. The membrane was prepared by blending 50% PLA (polylactic acid) with 50% PTMC (polytrimethylene carbonate). The prepared blends polymer membrane was more flexible than pure PLA membrane, as measured by glass‐transition temperature and tensile study. Cytotoxicity study revealed that PLA/PTMC blends membrane showed good biocompatibility. The membrane elicited slight tissue reaction based on the results of histological study. Thirty adult Japanese rabbits were used for the intestine adhesion model. The treatment group had PLA/PTMC membrane, the control group had chitosan, and the blank control group was not operated. The animals were housed for two weeks and sacrificed to investigate adhesion of intestine. Compared with the blank control group, the treatment group and the control group lowered the extent of adhesions (p < 0.01), but the treatment group was better than the control group (p < 0.05). The in‐vivo studies confirmed that PLA/PTMC blends membrane could prevent postoperative adhesions. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Water absorption characteristics of novel Cu/LDPE nanocomposite for use in intrauterine devices
Authors: Xia Xianping , Cai Shuizhou , Hu Junhui , Xie Changsheng
Published: April 2006

Intrauterine devices (IUDs), especially the copper‐containing IUDs (Cu‐IUDs), are one of the worldwide used forms for birth control, owing to their advantages of long‐lasting and high efficacy, economy, safety, and reversibility. However, it is not perfect for the existing Cu‐IUDs; some shortcomings related to its side effects have not been overcome yet. For this reason, a new Cu‐IUDs material, the copper/low‐density polyethylene (Cu/LDPE) nanocomposite, has been developed in our research team. The structure and water uptake characteristics of this new Cu‐IUDs material have been investigated by using X‐ray diffraction (XRD), Scanning electron microscopy (SEM), X‐ray energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FT‐IR), and gravimetric analysis in this paper. The results of XRD, SEM, EDS, and FT‐IR show three important outcomes associated with the structure of the nanocomposite. First, the nanocomposite is hybrid of the polymer and the copper nanoparticles (nano‐Cu). Second, porosities, nano‐Cu aggregates, and primary alcohol (RCH2OH) are existed in the nanocomposite. Third, the nano‐Cu aggregates are distributed uniformly in the polymer matrix in general. The results of Gravimetric analysis, which associated with the water uptake characteristics of the nanocomposite, exhibit that the water absorption behavior of the nanocomposite obeys the classical diffusion theory very well, the water uptake of the nanocomposite increases with the increasing of the nano‐Cu loading, and that the water uptake ability of the nanocomposite with 15.0 wt % nano‐Cu (50 nm in diameter) is about 150 times larger than that of the base resin and about 45 times higher than that of the Cu/LDPE microcomposite with 15.0 wt % copper microparticles (5 μm in diameter). These water uptake characteristics are mainly attributed to the structure of the Cu/LDPE composites and the size effect of the nano‐Cu. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Effect of high light intensity on cavity wall adaptation of a resin composite with a self‐etching primer system
Authors: Shinkai Koichi , Suzuki Shiro , Katoh Yoshiroh
Published: April 2006

This study evaluated the effect of high light intensity using a plasma arc lamp on the cavity wall adaptation of photo‐polymerized composite restorations. Bowl‐shaped cavities were prepared on the labial surfaces of extracted bovine teeth. Each cavity was restored with a resin composite restorative system (SE Bond & Clearfil AP‐X) and then polymerized using a plasma arc lamp (Arc Light II) with a series of light intensities, including 1100, 1200, 1300, 1400, 1500, and 1600 mW/cm2, and a halogen lamp (Candilux) with 400 mW/cm2 light intensity (n = 10). The photo‐irradiation time was adjusted for each group to receive a total energy output of approximately 16,000 mJ/cm2. The specimens were subjected to 2500 cycles of thermal fatigue and sectioned bucco‐lingualy through the center of the restoration. Contraction gaps on the sections were measured using a replica‐SEM observation technique. The degree of gap formation was determined as the ratio of the total length of the contraction gaps to the total length of the cavity wall on each sectioned specimen. The value was converted to a percentage. The data were statistically analyzed with Kruskal‐Wallis and Mann‐Whitney U tests at a 0.05 level of significance. There were no significant differences (p > 0.05) in the cavity adaptation among the composites polymerized by the plasma arc lamp with high light intensities and the composite polymerized with the halogen lamp with 400 mW/cm2 light intensity. There were no significant differences (p > 0.05) in the degree of cavity adaptation among the specimens polymerized with light intensities higher than 1100 mW/cm2. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Urease immobilization on an ion‐exchange textile for urea hydrolysis
Authors: Yeon Kyeong‐Ho , Lueptow Richard M
Published: April 2006

Ion‐exchange textiles are used as organic supports for urease immobilization with the aim of developing reactive fibrous materials able to promote urea removal. A non‐woven, polypropylene‐based cation‐exchange textile was prepared using UV‐induced graft polymerization. Urease was covalently immobilized onto the cation‐exchange textile using three different coupling agents: N‐(3‐dimethylaminopropyl)‐N′‐ethylcarbodiimide hydrochloride (EDC), N‐cyclohexyl‐N′‐(b‐[N‐methylmorpholino]ethyl)carbodiimide p‐toluenesulfonate (CMC), and glutaraldehyde (GA). The immobilized biocatalyst was characterized by means of FT‐IR spectrometry, SEM micrographs, dependence of the enzyme activity on pH and temperature, and according to the kinetic constants of the free and immobilized ureases. The biotextile prepared with EDC in the presence of N‐hydroxysuccinimide performs best. The optimum pH was 7.2 for the free urease and 7.6 for the immobilized ureases. The reactivity was maximal at 45 °C for free urease, 50 °C for biotextiles prepared using EDC or CMC, and 55 °C for biotextiles prepared with GA. The activation energy for the immobilized ureases was 4.73–5.67 kcal mol−1, which is somewhat higher than 4.3 kcal mol−1 for free urease. The urea conversion for a continuous‐flow immobilized urease reactor is nearly as good as a continuously stirred tank reactor having a much longer residence time, suggesting that the packed bed reactor had sufficient diffusive mixing and residence time to reach nearly optimal results. Urease immobilized on a biotextile using EDC has good storage and operational stability. Copyright © 2006 Society of Chemical Industry
Optimization of Nannochloropsis oculata growth using the response surface method
Authors: Spolaore Pauline , Joannis‐Cassan Claire , Duran Elie , Isambert Arsène
Published: April 2006

Optimization of Nannochloropsis oculata growth was undertaken using the response surface method. A central composite design was defined to study the effects of temperature, pH, incident light intensity and aeration rate on the maximum growth rate of the microalga. Using statistical analysis, the first model calculated to fit results was twice improved. The final model obtained was used to clarify the effects of each factor and their interactions on the growth of Nannochloropsis oculata. The optimum growth conditions of this microorganism were also estimated as 21 °C, 52 µmol photons m−2 s−1, pH 8.4 and 14.7 VVH of aeration rate. These conditions were tested and validated experimentally since the maximum growth rate achieved with these parameters, 0.0359 h−1, is the best reported in this study. Copyright © 2006 Society of Chemical Industry
Using fear appeals to promote cancer screening—are we scaring the wrong people?
Authors: Jones Sandra C. , Owen Neville
Published: April 2006

There is debate regarding the use of fear appeals (emphasizing severe threats to health) in social marketing, to encourage preventive behaviours, such as screening for breast cancer. While it has been found that fear appeals may result in attitude and behaviour change there is also the risk of inciting inappropriate levels of fear, motivating the wrong audience or instigating maladaptive behaviour in the target group such as denial or defensive avoidance. This study examined the impact of an experimental threat manipulation for mammography screening on a group of women in regional Australia. The study found that varying the level of threat had no impact on stated intentions of the women to undergo mammographic screening. However, it also found that high‐threat messages resulted in stronger negative emotional reactions and greater perceived susceptibility among younger women who are not the target group for screening in Australia. The results of this study emphasize the importance of limiting the use of high levels of threat in social marketing campaigns, and ensuring that campaigns are appropriately designed to specifically impact upon and motivate the target group.

Copyright © 2006 John Wiley & Sons, Ltd.
Nanocomposites at elevated temperatures: migration and structural changes
Authors: Lewin Menachem , Pearce E. M. , Levon Kalle , Mey‐Marom Abraham , Zammarano Mauro , Wilkie Charles A. , Jang Bok Nam
Published: April 2006

The possible effect of temperature stability of organic layered silicates (OLSs) on the structure and flammability behavior of polymer/montmorillonite (MMT) nanocomposites has been discussed in a previous publication. Above 200°C, the OLS begins to decompose, and the nanocomposite structure is gradually destroyed even before pyrolysis and combustion. Data on the decomposition of polymer/OLS mixtures upon isothermal thermogravimetric analysis (TGA) experiments are presented, and include rates and energies of activation at a range of temperatures from 200 to 400°C. Decomposition of OLSs in the presence of polymer is discussed in view of the decomposition of clay, pristine surfactant, and OLS. Accumulation of clay by migration to the surface of samples at a range of temperatures is indicated by X‐ray diffraction (XRD) and attenuated total reflectance Fourier transform infrared (ATR‐FTIR) measurements on the isothermally heated samples. Mechanistic considerations concerning changes in the structure of the nanocomposite, the decomposition of OLS, and migration of clay will be presented. Copyright © 2006 John Wiley & Sons, Ltd.
Nasal bone length at 11–14 weeks of pregnancy in the Korean population
Authors: Moon Min Hoan , Cho Jeong Yeon , Lee Yu Mi , Lee Young Ho , Yang Jae Hyug , Kim Moon Young , Park Seong Ho
Published: April 2006

Objectives

The aim of this study was to provide reference values for nasal bone length (NBL) scanned at 11–14 weeks' gestation in the Korean population and compare these values with those of the Caucasian and African–American populations.

Methods

From April 2004 to July 2004, fetal NBLs were measured in well‐dated, non‐anomalous fetuses at 11–14 weeks' gestation in the Korean population. Regression analysis was used to assess the relationship between NBL and crown‐rump length (CRL), and reference values including the 5th, 50th, and 95th percentile were calculated for each gestational age. The reference values in our study were compared with those of the Caucasian and African–American populations.

Results

A total of 982 cases were prospectively included in the study. NBL increased linearly with advance in CRL and was described by the equation; NBL (mm) = 0.433 + 0.022 × CRL (mm), R2 = 0.37. The median values (5%, 95%) were 1.5 mm (1.2 mm, 1.9 mm), 1.7 mm (1.4 mm, 2.1 mm), 1.9 mm (1.6 mm, 2.3 mm), and 2.1 mm (1.7 mm, 2.6 mm) for 11, 12, 13, and 14 weeks' gestation, respectively. The median values for each gestational age in the Korean population were significantly lower than those in the Caucasian and African–American populations (P < 0.0001).

Conclusion

There is a difference in NBL scanned at 11–14 weeks' gestation between the Korean and the Caucasian/African–American populations, and so racial adjustment is needed in the evaluation of the fetal nasal bone for current first‐trimester screening. Copyright © 2006 John Wiley & Sons, Ltd.
Euchromatic variant 16p+. Implications in prenatal diagnosis
Authors: López Pajares I. , Villa O. , Salido M. , Mori M. A. , Gonzalez A. , Lapunzina P. , De Torres M. L. , Vallcorba I. , Palomares M. , Fernández L. , Delicado A.
Published: April 2006

Background

Euchromatic imbalances at the cytogenetic level are usually associated with phenotypic consequences. Among the exceptions are euchromatic variants of chromosome 16 (16p+) with normal phenotype. There is a growing list of euchromatic duplications and deletions involving both G‐positive and G‐negative bands that seem to be phenotypically neutral, but these euchromatic variants are rare.

Objective

The aim of this report is to describe a new familial case of euchromatic variant 16p+ and to emphasise the misinterpretation of these rare euchromatic variants particularly when ascertained at prenatal diagnosis.

Methods and Results

Fluorescence in situ hybridisation with clone RP11‐261A7 showed an amplified signal in the larger chromosome 16. This clone contains FLJ43855 gene, similar to sodium‐ and chloride‐dependent creatine transporter.

Conclusion

So, this 16p+ variant that involves amplification of pseudogenetic sequences is considered a polymorphism in normal individuals. Copyright © 2006 John Wiley & Sons, Ltd.
Enhanced detection of sulfo‐peptides as onium salts in matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry
Authors: Ueki Masaaki , Yamaguchi Miyuki
Published: April 2006

A new two‐component system, consisting of a matrix and an onium salt as comatrix, is described for detection of sulfo‐peptides in the positive mode by matrix‐assisted desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOFMS). Binary iodonium salts were superior to quaternary phosphonium salts in terms of suppression of desulfation and salt formation with the carboxyl group. Of the iodonium salts examined, bis(4‐tert‐butylphenyl)iodonium (BTI) hexafluorophosphate and bromide were most effective in giving intensive molecular ion signals in the form of [M(BTI)+BTI]+. The conditions optimized for O‐sulfated tyrosine‐containing peptides could be applicable for O‐sulfated serine‐ and threonine‐containing peptides. In the case of a phospho‐peptide, a molecular ion appeared more intensively as a proton adduct than as a BTI adduct. Copyright © 2006 John Wiley & Sons, Ltd.
Tubulin assemblies as biomolecular templates for nanostructure synthesis: from nanoparticle arrays to nanowires
Authors: Behrens Silke , Habicht Wilhelm , Wu Jin , Unger Eberhard
Published: April 2006

Particles and nanotubes were synthesized after incubation with a metal salt and subsequent chemical reduction of the formed metal/biomolecule complexes. As investigated by scanning force microscopy (SFM) and electron microscopy, the nucleation and growth of metal clusters as well as continuous metal layers on microtubules lead to the template‐directed formation of micrometer‐long particle chains, or metal nanotubes. Copyright © 2006 John Wiley & Sons, Ltd.
Full discretization of some reaction diffusion equation with blow up
Authors: Barro Geneviève , Mampassi Benjamin , Some Longin , Ntaganda Jean , So Ousséni
Published: April 2006

This paper aims at the development of numerical schemes for nonlinear reaction diffusion problems with a convection that blows up in a finite time. A full discretization of this problem that preserves the blow — up property is presented as well as a numerical simulation. Efficiency of the method is derived via a numerical comparison with a classical scheme based on the Runge Kutta scheme.
A critical role for the histidine residues in the catalytic function of acyl‐CoA:cholesterol acyltransferase catalysis: Evidence for catalytic difference between ACAT1 and ACAT2
Authors: An Sojin , Cho Kyung-Hyun , Lee Woo Song , Lee Jie-Oh , Paik Young-Ki , Jeong Tae-Sook
Published: April 2006

To investigate a role for histidine residues in the expression of normal acyl‐CoA:cholesterol acyltransferase (ACAT) activity, the histidine residues located at five different positions in two isoenzymes were substituted by alanine, based on the sequence homology between ACAT1 and ACAT2. Among the 10 mutants generated by baculovirus expression technology, H386A–ACAT1, H460A–ACAT1, H360A–ACAT2, and H399A–ACAT2 lost their enzymatic activity completely. A reduction in catalytic activity is unlikely to result from structural changes in the substrate‐binding pocket, because their substrate‐binding affinities were normal. However, the enzymatic activity of H386A–ACAT1 was restored to <37% of the level of the wild‐type activity when cholesterol was replaced by 25‐hydroxycholesterol as substrate. H527A–ACAT1 and H501A–ACAT2, termed carboxyl end mutants, exhibit activities of ∼96% and ∼75% of that of the wild‐type. Interestingly, H425A–ACAT1 showed 59% of the wild‐type activity, in contrast to its equivalent mutant, H399A‐ACAT2. These results demonstrate that the histidine residues located at the active site are very crucial both for the catalytic activity of the enzyme and for distinguishing ACAT1 from ACAT2 with respect to enzyme catalysis and substrate specificity.
Mucosal interplay among commensal and pathogenic bacteria: Lessons from flagellin and Toll‐like receptor 5
Authors: Rumbo Martin , Nempont Clément , Kraehenbuhl Jean-Pierre , Sirard Jean-Claude
Published: April 2006

Toll‐like receptors (TLR) detect pathogen‐associated molecular patterns (PAMP) and play a crucial role in triggering immunity. Due to their large surfaces in direct contact with the environment, mucosal tissues are the major sites of PAMP‐TLR signalling. How innate and adaptive immunity are triggered through flagellin–TLR5 interaction is the main focus of the review. In view of recent reports on genetic polymorphism, we will summarize the impact of TLR5 on the susceptibility to mucosal infections and on various immuno‐pathologies. Finally, the contribution of TLRs in the induction and maintenance of mucosal homeostasis and commensal discrimination is discussed.
Fragmented Pathways to Care
Authors: Strike Carol , Rhodes Anne E. , Bergmans Yvonne , Links Paul
Published: April 2006

Using qualitative methods, this study examined how, and under what circumstances, suicidal men used mental health services. In particular, the analyses focused on fragmented pathways to care. Fifteen men with a history of suicidal and aggressive behaviors and a diagnosis of borderline personality disorder and/or antisocial personality disorder participated in semistructured interviews that consisted of questions about their mental health status and experiences with mental health and addiction services. Interviews were taped and transcribed. An iterative, inductive qualitative analytic process was used. Men followed a cyclical pattern wherein negative experiences with health care providers were said to be followed by avoidance of health care settings, crisis, and then by involuntary service utilization. Men identified five health care provider and three personal practices, and two types of episodes they believed to contribute to their fragmented pathways to care. Implementation of specialized interventions, and providing patients with more information and more opportunity to participate in decisions, may improve interactions between patients and providers and improve patients' mental health status.
Impaired phagocytic mechanism in annexin 1 null macrophages
Authors: Yona Simon , Heinsbroek Sigrid E M , Peiser Leanne , Gordon Siamon , Perretti Mauro , Flower Roderick J
Published: April 2006

The role of the anti‐inflammatory protein annexin‐A1 (Anx‐A1) in the phagocytic process has been investigated using a murine bone marrow culture‐derived macrophage model from Anx‐A1+/+ and Anx‐A1−/− mice.

Macrophages prepared from Anx‐A1−/− mice exhibited a reduced ingestion of zymosan, Neisseria meningitidis or sheep red blood cells, when compared to Anx‐A1+/+ cells and in the case of zymosan this effect was also mirrored by a reduced clearance in vivo when particles were injected into the peritoneal cavity of Anx‐A1−/− mice.

The ablation of the Anx‐A1 gene did not cause any apparent cytoskeletal defects associated with particle ingestion but the cell surface expression of the key adhesion molecule CD11b was depressed in the Anx‐A1−/− cells providing a possible explanation for the attenuated phagocytic potential of these cells.

The production of the cytokines TNFα and IL‐6 was increased in Anx‐A1−/− macrophages following phagocytosis of all types of particle.

British Journal of Pharmacology (2006) 148, 469–477. doi:10.1038/sj.bjp.0706730