bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gel effect in the bulk reversible addition–fragmentation chain transfer polymerization of methyl methacrylate: Modeling and experiments
Authors: Peklak A. David , Butté Alessandro , Storti Giuseppe , Morbidelli Massimo 
Published: December 2005

AbstractA model for the evaluation of the kinetics and the chain length distribution in living/controlled radical polymerization mediated by reversible addition–fragmentation chain transfer (RAFT) in bulk is presented. Using the free volume theory, the model accounts for the diffusion limitations over both termination and RAFT exchange reactions. Model predictions are compared to experimental results of methyl methacrylate polymerization with cumyl dithiobenzoate as a RAFT agent. It is shown that the polymerization retardation observed in living systems at large conversions is well predicted. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1071–1085, 2006
Epoxy resin containing polyphenylsilsesquioxane: Preparation, morphology, and thermomechanical properties
Authors: Ni Yong , Zheng Sixun 
Published: December 2005

AbstractPolyphenylsilsesquioxane (PPSQ) was incorporated into an epoxy resin to prepare organic–inorganic composites, and two strategies were adopted to afford composites with different morphologies. Phase separation induced by polymerization occurred in the physical blending system. However, nanostructured composites were obtained when a catalytic amount of aluminum triacetylacetonate was added to mediate the reaction between PPSQ and diglycidyl ether of bisphenol A (DGEBA). The intercomponent reaction significantly suppressed the phase separation on the micrometer scale. Organic–inorganic composites with different morphologies displayed quite different thermomechanical properties. Both differential scanning calorimetry and dynamic mechanical analysis showed that the nanostructured composites possessed higher glass‐transition temperatures than the phase‐separated composites with the same loading of PPSQ, although the intercomponent reaction between PPSQ and DGEBA reduced the crosslinking density of the epoxy matrix. This result was ascribed to the presence of nanosized PPSQ domains in the nanostructured composites, which acted as physical crosslinking sites and thus reinforced the epoxy networks. The nanoreinforcement of the PPSQ domains afforded the enhanced dynamic storage modulus for the nanostructured composites in comparison with the phase‐separated composites with a PPSQ concentration less than 15 wt %. In terms of thermogravimetric analysis, the organic–inorganic composites displayed improved thermal stability and flame retardancy. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1093–1105, 2006
Further study of the viscoelastic phase separation of cyanate ester modified with poly(ether imide)
Authors: Zhan Guozhu , Yu Yingfeng , Tang Xiaolin , Tao Qingsheng , Li Shanjun 
Published: December 2005

AbstractIn this study, the viscoelastic phase separation process was studied further by time‐resolved light scattering, differential scanning calorimetry, and scanning electron microscopy in the system of poly(ether imide)‐modified bisphenol‐A dicyanate. It was observed that the evolution time of phase structure and relaxation time of diffusion flow of the bisphenol‐A dicyanate were similar with the phase diagram of curing conversion versus content of PEI. The results suggested that the viscoelastic phase separation was affected by the curing conversion of the system at the onset point of phase separation. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 517–523, 2006
Warming of permafrost in the Arctic National Wildlife Refuge, Alaska
Authors: Osterkamp T. E. , Jorgenson J. C. 
Published: December 2005

AbstractPermafrost borehole temperatures were measured in 1985, 1998, and 2004 on Barter Island near the village of Kaktovik and in the Arctic National Wildlife Refuge (Arctic NWR) north of the Brooks Range. These measurements indicate that the century‐long warming documented for the central and western Arctic has also occurred in the region near Barter Island and in the northern Arctic NWR. At Kaktovik, the warming occurred during the second quarter of the 20th century or earlier and its magnitude exceeded 0.8°C. A more recent warming (since the mid to late 1980s) similar to that in the central and western Arctic is also occurring on Barter Island and in the northern Arctic NWR. Near Kaktovik, the permafrost warmed about 2 to 3°C from 1985 to 2004. In the northern Arctic NWR, on a line extending southward from Tapkaurak Point, it warmed about 1.5 to 2°C from 1985 to 1998. If air temperatures warm 5°C over the next century, as predicted, some of the permafrost in the northern Arctic NWR would be expected to thaw. Copyright © 2005 John Wiley & Sons, Ltd.
Expression of prothymosin alpha is correlated with development and progression in human prostate cancers
Authors: Suzuki Shugo , Takahashi Satoru , Takahashi Seishiro , Takeshita Kentaro , Hikosaka Atsuya , Wakita Toshiaki , Nishiyama Naoki , Fujita Tamio , Okamura Takehiko , Shirai Tomoyuki 
Published: December 2005

AbstractBACKGROUNDOur previous study clearly demonstrated that decreased expression of prothymosin alpha (PTMA) was associated with inhibition of rat prostate carcinogenesis by isoflavones. The purpose of the present investigation was to provide a better understanding of the role of PTMA in human prostate cancers.METHODS AND RESULTSPTMA expression in 68 prostate cancer cases and in prostate cancer cell lines was examined by immunohistochemistry and immunoblotting, and its levels were increased with progression from normal epithelium, through prostatic intraepithelial neoplasia (PIN) to carcinomas, correlating with the Gleason's pattern. All cell lines studied (LNCaP, 22Rv1, DU145, and PC3) showed high PTMA expression compared with prostate epithelial cells (PrEC). Knockdown of PTMA expression in PC3 cells by RNAi resulted in the inhibition of both cell growth and invasion in vitro.CONCLUSIONSThe present study clearly demonstrated that PTMA expression is intimately involved in the differentiation and progression of human prostate cancers, and could be a target for therapy and diagnostic purposes. © 2005 Wiley‐Liss, Inc.
Quantum chemical model study of the acyl migration in 2′(3′)‐formylnucleosides
Authors: Rangelov Miroslav A. , Vayssilov Georgi N. , Petkov Dimiter D. 
Published: December 2005

AbstractThis work reports a density functional study of the mechanism of acyl migration between vicinal OH groups in monoformylated cis‐tetrahydrofuran‐3,4‐diol as a model system for the acyl migration in amino‐acylated tRNA. In addition, migration toward the ionized hydroxyl group was modeled, which simulates the process in the presence of basic reagents. The polarized continuum model (PCM) for four solvents evaluated the solvent effect on the reaction energetics. The computational results suggest that the stepwise mechanism via an orthoester intermediate is preferred by 45–48 kJ/mol over the concerted mechanism where migration of the formyl group, and the proton from the vicinal OH group occurs simultaneously via a four‐atom transition state. The conformational constrains of the THF ring could increase the energy of the transition states by ∼24 and 37 kJ/mol for the stepwise and concerted reaction paths, respectively. The calculated lowest activation energy of the reaction both in vacuum and in solvents is rather high, at 188 and 172–182 kJ/mol, respectively. These results suggest that in real systems, the process is most likely catalyzed by preliminary deprotonation of the vicinal OH group. In this case, the formyl group migration proceeds spontaneously, and the intermediate formed is 15–30 kJ/mol more stable than the initial anion of the monoformylated diol. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Multiobjective Tabu Search method used in chemistry
Authors: Rusu T. , Bulacovschi V. 
Published: December 2005

AbstractThe use of a combined artificial intelligence method in macromolecular chemistry design is described. This method implies a Back‐Propagation (BP) Neural Network, modified for two‐dimensional input data and for a system composed of a genetic algorithm extended by a Tabu Search operator used to incorporate high‐level chemical knowledge: thermodynamic polymer properties. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Polynomial time perfect sampling algorithm for two‐rowed contingency tables
Authors: Kijima Shuji , Matsui Tomomi 
Published: December 2005

AbstractThis paper proposes a polynomial time perfect (exact) sampling algorithm for 2 ×ncontingency tables. The algorithm is based on monotone coupling from the past (monotone CFTP) algorithm. The expected running time is bounded by O(n3lnN) wherenis the number of columns andNis the total sum of all entries. © 2005 Wiley Periodicals, Inc. Random Struct. Alg., 2006
Degree distribution of the greatest common divisor of polynomials over 𝔽q
Authors: Gao Zhicheng , Panario Daniel 
Published: December 2005

AbstractWe study the degree distribution of the greatest common divisor of two or more random polynomials over a finite field 𝔽q. We provide estimates for several parameters like number of distinct common irreducible factors, number of irreducible factors counting repetitions, and total degree of the gcd of two or more polynomials. We show that the limiting distribution of a random variable counting the total degree of the gcd is geometric and that the distributions of random variables counting the number of common factors (with and without repetitions) are very close to Poisson distributions when q is large. © 2005 Wiley Periodicals, Inc. Random Struct. Alg., 2006
MAXk‐CUT and approximating the chromatic number of random graphs
Authors: Coja‐Oghlan Amin , Moore Cristopher , Sanwalani Vishal 
Published: December 2005

AbstractWe consider the MAXk‐CUT problem on random graphsGn,p. First, we bound the probable weight of a MAXk‐CUT using probabilistic counting arguments and by analyzing a simple greedy heuristic. Then, we give an algorithm that approximates MAXk‐CUT in expected polynomial time, with approximation ratio 1 +O((np)‐1/2). Our main technical tool is a new bound on the probable value of Frieze and Jerrum's semidefinite programming (SDP)‐relaxation of MAXk‐CUT on random graphs. To obtain this bound, we show that the value of the SDP is tightly concentrated. As a further application of our bound on the probable value of the SDP, we obtain an algorithm for approximating the chromatic number ofGn,p, 1/n≤p≤ 0.99, within a factor ofO((np)1/2) in polynomial expected time, thereby answering a question of Krivelevich and Vu. We give similar algorithms for random regular graphs. The techniques for studying the SDP apply to a variety of SDP relaxations of further NP‐hard problems on random structures and may therefore be of independent interest. For instance, to bound the SDP we estimate the eigenvalues of random graphs with given degree sequences. © 2005 Wiley Periodicals, Inc. Random Struct. Alg., 2006
The degree sequences and spectra of scale‐free random graphs
Authors: Jordan Jonathan 
Published: December 2005

AbstractWe investigate the degree sequences of scale‐free random graphs. We obtain a formula for the limiting proportion of vertices with degreed, confirming non‐rigorous arguments of Dorogovtsev, Mendes, and Samukhin (Phys Rev Lett 85 (2000), 4633). We also consider a generalization of the model with more randomization, proving similar results. Finally, we use our results on the degree sequence to show that for certain values of parameters localized eigenfunctions of the adjacency matrix can be found. © 2005 Wiley Periodicals, Inc. Random Struct. Alg., 2006
Bayesian decision procedures for dose‐escalation based on evidence of undesirable events and therapeutic benefit
Authors: Whitehead John , Zhou Yinghui , Stevens John , Blakey Graham , Price Jim , Leadbetter Joanna 
Published: December 2005

AbstractIn this paper, Bayesian decision procedures are developed for dose‐escalation studies based on bivariate observations of undesirable events and signs of therapeutic benefit. The methods generalize earlier approaches taking into account only the undesirable outcomes. Logistic regression models are used to model the two responses, which are both assumed to take a binary form. A prior distribution for the unknown model parameters is suggested and an optional safety constraint can be included. Gain functions to be maximized are formulated in terms of accurate estimation of the limits of a ‘therapeutic window’ or optimal treatment of the next cohort of subjects, although the approach could be applied to achieve any of a wide variety of objectives. The designs introduced are illustrated through simulation and retrospective implementation to a completed dose‐escalation study. Copyright © 2006 John Wiley & Sons, Ltd.
Application of reliability coefficients in cDNA microarray data analysis
Authors: He Wenqing , Bull Shelley B. , Gokgoz Nalan , Andrulis Irene , Wunder Jay 
Published: December 2005

AbstractGene expression microarray technology has been widely used in areas such as human cancer research to identify molecular characteristics of sample specimens. The microarray study, however, is a very complicated procedure which involves numerous sources of variability that may be either systematic or random. Systematic variation is often eliminated by applying normalization procedures, but at present there are no standard criteria available to evaluate the performance of a particular normalization approach. In this paper, we propose a reliability‐type coefficient as a criterion to assess the effectiveness of normalization procedures in eliminating systematic variation. Simulation studies show that this criterion performs reasonably well in a range of settings. The proposed method is illustrated using a subset of an ongoing microarray study of soft‐tissue sarcoma. Copyright © 2005 John Wiley & Sons, Ltd.
Shared random effects analysis of multi‐state Markov models: application to a longitudinal study of transitions to dementia
Authors: Salazar Juan C. , Schmitt Frederick A. , Yu Lei , Mendiondo Marta M. , Kryscio Richard J. 
Published: December 2005

AbstractMulti‐state models are appealing tools for analysing data about the progression of a disease over time. In this paper, we consider a multi‐state Markov chain with two competing absorbing states: dementia and death and three transient non‐demented states: cognitively normal, amnestic mild cognitive impairment (amnestic MCI), and non‐amnestic mild cognitive impairment (non‐amnestic MCI). The likelihood function for the data is derived and estimates for the effects of the covariates on transitions are determined when the process can be viewed as a polytomous logistic regression model with shared random effects. The presence of a shared random effect not only complicates the formulation of the likelihood but also its evaluation and maximization. Three approaches for maximizing the likelihood are compared using a simulation study; the first method is based on the Gauss‐quadrature technique, the second method is based on importance sampling ideas, and the third method is based on an expansion by Taylor series. The best approach is illustrated using a longitudinal study on a cohort of cognitively normal subjects, followed annually for conversion to mild cognitive impairment (MCI) and/or dementia, conducted at the Sanders Brown Center on Aging at the University of Kentucky. Copyright © 2005 John Wiley & Sons, Ltd.
Modelling menstrual status during and after adjuvant treatment for breast cancer
Authors: Szwarc Suzanne E. , Bonetti Marco 
Published: December 2005

AbstractFailure time data may consist of the observation of an event whose cause is unknown due to the censoring or lack of a second event that could identify the cause of the first event. Standard competing‐risks methodology does not apply to this setting because the cause of the event is not always identifiable. Moreover, one cannot assume that the entire population will eventually experience the event of interest, and the observation is potentially censored for all patients. The model that we describe in this article is motivated by a breast cancer clinical trial conducted by the International Breast Cancer Study Group (IBCSG). Because some breast cancer adjuvant treatments for premenopausal patients who have undergone surgery cause the interruption of menses, or amenorrhoea, it is of interest to describe the process by which menses discontinue and resume after treatment is completed. The process is complicated by the fact that natural menopause also occurs in the patient population, and that treatment‐induced amenorrhoea is not distinguishable from menopause unless menses are observed to resume after treatment completion. We discuss a parametric model for the time to amenorrhoea and for the time to the recovery of menses, also accounting for the presence of censoring and for the possibility that treatment causes an anticipation of natural menopause. Copyright © 2005 John Wiley & Sons, Ltd.
A mixed‐effects model for cognitive decline with non‐monotone non‐response from a two‐phase longitudinal study of dementia
Authors: Shen Changyu , Gao Sujuan 
Published: December 2005

AbstractMost longitudinal studies of elderly are characterized by substantial drop‐out due to death and many other factors beyond the control of the investigators. In a two‐phase longitudinal study of dementia, subjects with cognitive impairment skip the first phase survey in the next follow‐up, leading to intermittent missing variables measured in that phase. In the context of analysing pre‐dementia cognitive decline in an elderly population, both of the two causes of non‐response can potentially be informative in the sense that the missingness is dependent on the unobserved outcome. To take these factors into account, mixed‐effects models are constructed to allow the outcome and the multiple causes of missing values to share the same ‘random parameter’ or random effect. The crucial assumption of our model is that the random effects of the model for the outcome and that of the model for the missing‐data indicators are linked in a deterministic manner. It can be thought of as an approximation of a more general and realistic situation, in which the two models have distinct, yet dependent, random effects. We conduct a simulation study to investigate possible deviations of the estimates under such a scenario. A second simulation illustrates the magnitude of the bias in estimating the difference of decline rate between two groups when the random effects are linked in different manners for the two groups. Copyright © 2005 John Wiley & Sons, Ltd.
Exploring cultural dimensions of gender and management in the Middle East
Authors: Metcalfe Beverly Dawn 
Published: December 2005

AbstractThis study analyzes the experiences of female professionals working in three case study countries in the Middle East: Bahrain, Jordan, and Oman. Data were gleaned while conducting management and cultural training for female managers. Results highlight the importance of women to economic development and the complexity of the interrelations between gender, organization, and Islamic values. The study reveals that women have advanced in management in the Middle East but have career and development constraints due to strong gender roles in Islamic culture. The study suggests strategies for HR and for gender and development to support international business. © 2006 Wiley Periodicals, Inc.
Wet clutch transmission fluid for AWD differentials: base fluid influence on friction characteristics
Authors: Mäki Rikard , Ganemi Bager , Olsson Richard 
Published: December 2005

AbstractDuring the past few years several electronically controllable automotive transmission systems, where wet clutches are used as intelligent differentials, have emerged in the market. In this type of application the anti‐shudder properties of the lubricants are of vital importance. This paper investigates the influence of base fluids on the anti‐shudder properties of transmission fluids for wet clutches in all‐wheel‐drive systems. The investigated all‐wheel‐drive system featuring a wet multi‐plate clutch with a sintered brass‐based friction material is described. The test equipment used to determine the frictional characteristics of the transmission fluid is described. The parameters studied include base fluid type and base fluid viscosity. It is shown that the choice of base fluid has no impact on torque capacity, but that the base fluid influences the temperature dependence of the dynamic friction and the anti‐shudder properties. It is also shown that the major effect on the friction characteristics is caused by additive effects rather than base fluid effects. Copyright © 2006 John Wiley & Sons, Ltd.
Lateralized deficit of response inhibition in early-onset schizophrenia
Authors: BELLGROVE MARK A. , CHAMBERS CHRISTOPHER D. , VANCE ALASDAIR , HALL NICOLE , KARAMITSIOS MARY , BRADSHAW JOHN L. 
Published: December 2005

Background. The ability to inhibit inappropriate or unwanted actions is a key element of executive control. The existence of executive function deficits in schizophrenia is consistent with frontal lobe theories of the disorder. Relatively few studies have examined response inhibition in schizophrenia, and none in adolescent patients with early-onset schizophrenia (EOS).Methods. Twenty-one adolescents with the onset of clinically impairing psychosis before 19 years of age and 16 matched controls performed a stop-signal task to assess response inhibition. The patients with EOS were categorized as paranoid (n=10) and undifferentiated subtypes (n=11). The undifferentiated group had higher levels of negative symptomatology. Stop-signal reaction time (SSRT) and go-signal reaction time (Go-RT) were analysed with respect to hand of response.Results. The undifferentiated early-onset patients had significantly longer SSRTs, indicative of poor response inhibition, for the left hand compared to the paranoid early-onset patients and control participants. No differences existed for inhibitory control with the right hand. The three groups did not differ in Go-RT.Conclusions. Our results indicate a specific lateralized impairment of response inhibition in patients with undifferentiated, but not paranoid, EOS. These findings are consistent with reports of immature frontostriatal networks in EOS and implicate areas such as the pre-motor cortex and supplementary motor area (SMA) that are thought to play a role in both voluntary initiation and inhibition of movement.