bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fighting child pornography: Exploring didactics and student engagement in social informatics
Authors: Godejord Per Arne 
Published: December 2006

AbstractThis article describes a unique educational project that was implemented in the undergraduate study of computer science in 2002. Nesna University College has been using the example of sexual abuse of children in case study teaching in social informatics, in order to create an environment for intrinsically motivated learning. The project also gave the students a unique opportunity to get involved both emotionally and practically in the field of social informatics. The project is run in cooperation with Save the Children Norway and the Norwegian National Crime Squad. Nesna University College has the only computer science program in the world that has sexual abuse of children as the main topic on the curriculum. The computer science students provide both the Save the Children Norway and the National Criminal Investigation Service with reports on various topics such as secure chat, camera phones and possible abuse, Freenet as a tool for sexual abuse, etc. This exceptional cooperation between higher education and public and private organizations in this field makes the project not only unique, but might also be a major factor in both the willingness of students to learn social informatics and their development of skills in the various topics of social informatics.
Quick multivariate kernel density estimation for massive data sets
Authors: Cheng K. F. , Chu C. K. , Lin Dennis K. J. 
Published: December 2006

AbstractMassive data sets are becoming popular in this information era. Due to the limitation of computer memory space and the computing time, the kernel density estimation for massive data sets, although strongly demanding, is rather challenging. In this paper, we propose a quick algorithm for multivariate density estimation which is suitable for massive data sets. The term quick is referred to indicate the computing ease. Theoretical properties of the proposed algorithm are developed. Its empirical performance is demonstrated through a credit card example and numerous simulation studies. It is shown that in addition to its computational ease, the proposed algorithm is as good as the traditional methods (for the situations where these traditional methods are feasible). Copyright © 2006 John Wiley & Sons, Ltd.
Science, engineering, and statistics
Authors: Davis T. P. 
Published: December 2006

AbstractSymmetry and parsimony, together with unification through synthesis are important principles that govern the character of physical law. We show how these principles can be applied to engineering to develop an approach to reliability, and engineering in general, that centres on the identification, detection, and avoidance of failure modes through design. A definition of reliability, not presented in terms of probability, but rather based on physics, geometry, and the properties of materials, will be emphasized to support this approach. We will also show how the nature of the inductive–deductive learning cycle provides the framework for statistical science to be embedded into engineering practice, with particular regard to improving reliability through failure mode avoidance. Copyright © 2006 John Wiley & Sons, Ltd.
Measurement error bias in pharmaceutical cost‐effectiveness analysis
Authors: C. Marschner Ian 
Published: December 2006

AbstractDrug development in the pharmaceutical industry is increasingly influenced by measures of cost‐effectiveness, such as cost per life‐year gained, and some governments make decisions about whether to pay for drugs based on cost‐effectiveness considerations. While cost per life‐year gained is a key measure of cost‐effectiveness, costs associated with the intermediate outcome of improving a biomarker, such as cholesterol level or blood pressure, provide important supplementary information, particularly where mortality data may be limited. In this case, cost‐effectiveness can be interpreted as the additional cost per unit time of achieving an additional beneficial biomarker response to treatment. A problem in this context is that biomarker assessment is typically subject to measurement error which leads to bias in assessing the benefit of a drug, and hence in the assessment of its cost‐effectiveness. We discuss the adjustment of cost‐effectiveness analyses for measurement error and consider the potential magnitude of bias that can arise. Using example calculations in the context of cholesterol‐lowering therapy, it is demonstrated that such biases can be significant, leading to costs being overestimated by in excess of 25%. Ignoring measurement error in cost‐effectiveness analyses can, therefore, have a substantial effect on the interpretation of such analyses. Copyright © 2006 John Wiley & Sons, Ltd.
On goodness‐of‐fit for homogeneity and proportional hazards
Authors: Bagdonavičius Vilijandas , Nikulin Mikhail 
Published: December 2006

AbstractThe classical goodness‐of‐fit tests for homogeneity and proportional hazards have small power in the case of alternatives when crossings of survival functions are possible. We give test statistics which are oriented against wide classes of alternatives including single or multiple crossings of survival functions. The limit distributions of the test statistics are derived. Power of some tests are investigated by simulation. Copyright © 2006 John Wiley & Sons, Ltd.
Examining the effects of customer service management (CSM) on perceived business performance via structural equation modelling
Authors: Yap Bee Wah , Khong Kok Wei 
Published: December 2006

AbstractStructural equation modelling (SEM) is a useful multivariate technique to investigate the causal relationships between variables. This paper uses SEM to model the relationships between critical success factors (CSFs) of business process reengineering (BPR) implementations, customer service management (CSM) and perceived business performance (PBP) in Malaysian banking institutions. SEM results show that Management Competence has significant positive effects on PBP and CSM. Information technology (IT) infrastructure capabilities has significant effects on CSM but statistically insignificant (but positive) effect on PBP. Similarly Effective Process Redesign has statistically insignificant (but positive) effect on CSM and PBP. Results also show that CSM has a positive and significant association with PBP. Copyright © 2006 John Wiley & Sons, Ltd.
Variable second‐order inclusion probabilities during the sampling of industrial mixtures of particles
Authors: Geelhoed Bastiaan 
Published: December 2006

AbstractDuring analysis and inspection of materials, the mass concentration of a compound in a sample is often used as an estimate for the mass concentration in the population. Depending upon the material and the analysis technique, sample masses vary from several grams to up to several kilograms. An equation for the relation between the sample mass and the variance of the sample concentration allows calculation of the minimum sample mass, defined as the sample mass for which the relative standard deviation of the sample estimator is equal to a maximum allowable value. Application of Gy's theory may result in inaccurate estimates for the minimum sample mass when the selections of the particles are dependent events. The minimum sample mass may be underestimated, resulting in a relatively high variance of the sample concentration, or overestimated, leading to higher sample processing costs. In this contribution, a variable second‐order inclusion probability is proposed. Two estimators for the variance are derived, including an estimator based on the Horvitz–Thompson estimator. The estimators are compared using samples of aggregates. Copyright © 2006 John Wiley & Sons, Ltd.
Interaction between stock indices via changepoint analysis
Authors: Lenardon Martin J. , Amirdjanova Anna 
Published: December 2006

AbstractStock market indices from several countries are modelled as discretely sampled diffusions whose parameters change at certain times. To estimate these times of parameter changes we employ both a sequential likelihood‐ratio test and a non‐parametric, spectral algorithm designed specifically for time series with multiple changepoints. Finally, we use point‐process techniques to model relationships between changepoints of different financial time series. Copyright © 2006 John Wiley & Sons, Ltd.
Experimental designs for 2‐colour cDNA microarray experiments
Authors: Nguyen Nam‐Ky , Williams E. R. 
Published: December 2006

AbstractKerr and Churchill (Biostatistics2001;2:183–201) showed how varieties (e.g. type of tissues, drug treatments, etc.) are paired onto arrays by a catalogue of A‐optimal incomplete block designs (IBDs) for 6–10 varieties (v), and number of blocks of size 2 betweenvand$ \left(v \atop 2 \right)$. These A‐optimal IBDs were obtained by (i) generating all non‐isomorphic connected graphs onvvertices using Brendan McKay's,MAKEGprogram (http://cs.anu.edu.au/people/bdm/nauty/) and (ii) comparing all designs of the same size on the basis of A‐optimality to obtain the best ones.In this paper we will give a quick overview on IBDs and describe an algorithmic approach to extend the mentioned catalogue. We aim at IBDs with up to 100 varieties with equal as well as unequal replications. A catalogue of 2007 IBDs is given. We will also extend the concept ofevendesigns in Kerr and Churchill (Biostatistics2001;2:183–201) torow‐orthogonaldesigns. Copyright © 2006 John Wiley & Sons, Ltd.
Controlling‐dependent process steps using variable sample size control charts
Authors: Yang Su‐Fen , Su Hui‐Chun 
Published: December 2006

AbstractThe article considers the variable process control scheme for two dependent process steps. We construct variable sample size (VSS) ZX̄ and Zē control charts to effectively monitor the quality variable produced by the first process step and the quality variable produced by the second process step 2, respectively. The performance of the proposed VSS control charts is measured by the adjusted average time to signal (AATS) using a Markov chain approach. An example of producing cotton yarn system shows the application and performance of the proposed VSS ZX̄ and Zē control charts in detecting shifts in process mean. Furthermore, the performance of the VSS ZX̄ and Zē control charts and the fixed sample size (FSS) ZX̄ and Zē control charts are compared by numerical analysis results. These demonstrate that the former is much faster in detecting small shifts in mean. Copyright © 2006 John Wiley & Sons, Ltd.
Consistent Estimation of the Expected Brier Score in General Survival Models with Right‐Censored Event Times
Authors: Gerds Thomas A. , Schumacher Martin 
Published: December 2006

AbstractIn survival analysis with censored data the mean squared error of prediction can be estimated by weighted averages of time‐dependent residuals. Graf et al. (1999) suggested a robust weighting scheme based on the assumption that the censoring mechanism is independent of the covariates. We show consistency of the estimator. Furthermore, we show that a modified version of this estimator is consistent even when censoring and event times are only conditionally independent given the covariates. The modified estimators are derived on the basis of regression models for the censoring distribution. A simulation study and a real data example illustrate the results. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Demethyloleuropein and β‐glucosidase activity in olive fruits
Authors: Sivakumar Ganapathy , Briccoli Bati Caterina , Uccella Nicola 
Published: December 2006

AbstractDemethyloleuropein plays a major role in the defense mechanism of olive fruits. To understand how this molecule is metabolized during different stages of maturation of olive fruits, a biomolecular approach to identify the demethyloleuropein chemistry was employed. The β‐glucosidase activity in crude extracts was assayed spectrophotometrically using the chromogenic substrate p‐nitrophenyl‐β‐D‐glucopyranoside. Demethyloleuropein was extracted and identified by HPLC‐MS from both infected and uninfected olive fruits at different physiological stages. The release of more functionally relevant dialdehydes in uninfected fruits was investigated using ESIMS/ MS. In fruits harvested in October, the activity of β‐glucosidase was significantly enhanced in uninfected fruits when compared to the infected fruits. Quantitative differences in the demethyloleuropein content from uninfected fruits showed the highest values (5.09 mg/g) in October, whereas lower levels (4.44 mg/g) were found in infected fruits. The results demonstrated that demethyloleuropein derivatives could be influenced by β‐glucosidase activity to improve the quality of the olive products with the best dialdehyde nutraceutical content.
One‐step purification of Taq DNA polymerase using nucleotide‐mimetic affinity chromatography
Authors: Melissis Sotirios , Labrou Nikolaos E. , Clonis Yannis D. 
Published: December 2006

AbstractThe thermostable Thermus aquaticus DNA polymerase (Taq Pol) has been the key factor in transforming the initial PCR method into one with huge impact in molecular biology and biotechnology. Therefore, the development of effective affinity adsorbents for the purification of Taq Pol, as well as other DNA polymerases, attracts the attention of the enzyme manufacturers and the research laboratories. In this report we describe a simple protocol for the purification of Taq Pol from E. coli lysates, leading to enzymes of high specific activity and purity. The protocol is based on a single affinity chromatography step, featuring an immobilized ligand selected from a structure‐biased combinatorial library of dNTP‐mimetic synthetic ligands. The ligand library was screened for its ability to bind and purify Taq Pol from E. coli lysates. One immobilized ligand (mABSGu) of the general formula X‐Trz‐Y, bearing 9‐aminoethylguanine (AEGu) and aniline‐2‐sulfonic acid (mABS) linked on the triazine scaffold (Trz), displayed the highest purifying ability. Adsorption equilibrium studies with this affinity ligand and Taq Pol determined a dissociation constant (KD) of 0.12 mM for the respective complex, whereas ATP prevented the formation of the mABSGu‐Taq Pol complex. The mABSGu affinity adsorbent was exploited in the development of a facile Taq Pol purification protocol, affording homogeneous enzyme (>99% purity, ∼61 500 U/mg) in a single chromatography step. Quality control tests showed that Taq Pol purified on the mABSGu affinity adsorbent is free of nucleic acids and contaminating nuclease activities.
Expression of an acetyl‐CoA synthase and a CoA‐transferase in Escherichia coli to produce modified taxanes in vivo
Authors: Loncaric Catherine , Ward Amanda F. , Walker Kevin D. 
Published: December 2006

AbstractPrevious in vitro studies revealed that the 10‐deacetylbaccatin III 10β‐O‐acetyltransferase (DBAT) from Taxus can catalyze the transfer of acetyl, propionyl or n‐butyryl from CoA to the C10‐hydroxyl of 10‐deacetylbaccatin III. Accordingly, Escherichia coli JM109 were transformed to recombinantly express dbat, and this enzyme function was coupled to that of acetyl‐CoA synthase (acs, EC 6.2.1.1) expressed from and regulated by genes encoded on the bacterial chromosome. Incubation of the bacteria with 10‐deacetylbaccatin III and increasing concentrations of acetic acid revealed an in vivo conversion (∼10%) of substrate to natural product baccatin III (C10‐acetylated), which was remarkably similar to the relative conversion without acid supplementation. Incubation of the modified E. coli with 5 mM propionic acid, revealed a fivefold increase in the conversion (∼13%) of 10‐deacetylbaccatin III to 10‐deacetyl‐10‐propionylbaccatin III, compared to ∼2% conversion in the absence of exogenous propionate. To produce the butyrylbaccatin III analog in vivo, bacteria were engineered to co‐express the dbat and atoAD (EC 2.8.3.8) genes; the latter encodes an acetoacetate: acetyl‐CoA CoA‐transferase that activates butyrate to butyryl CoA. The bacteria were incubated with 10‐deacetylbaccatin III and 25‐100 mM butyrate, and a maximum of ∼2.6% conversion to 10‐butyrylbaccatin III was observed compared to ∼0.6% conversion when no exogenous butyrate was supplied.
Identification of tunnels in proteins, nucleic acids, inorganic materials and molecular ensembles
Authors: Damborský Jiří , Petřek Martin , Banáš Pavel , Otyepka Michal 
Published: December 2006

AbstractThe knowledge of the access paths connecting interior of molecular systems with surrounding environment is important for the understanding of structurefunction relationships and engineering of molecules for biotechnological applications. CAVER is a computer program developed for calculations of tunnels, channels or pores in the biomolecules, inorganic materials and molecular ensembles. The algorithm performs a skeleton search based on a reciprocal distance function grid. The algorithm is implemented in the stand‐alone version, web version and as plug‐in for PyMol. CAVER is available from the website http://loschmidt.chemi.muni.cz/caver.
Effect of osteonectin‐derived peptide on the viscoelasticity of hydrogel/apatite nanocomposite scaffolds
Authors: Sarvestani Alireza S. , He Xuezhong , Jabbari Esmaiel 
Published: December 2006

AbstractHydrogel/apatite nanocomposites are the ideal biomaterial to mimic the physio‐chemical and biologic properties of the bone and to fabricate scaffolds for bone regeneration. The objective of this work was to investigate the effect of an osteonectin derived glutamic acid sequence on the viscoelastic properties of poly(lactide‐ethylene oxide‐fumarate) (PLEOF)/apatite composite, as a model degradable material in bone regeneration. Osteonectin is an extracellular acidic glycoprotein of the bone matrix, which is believed to be involved in linking the collagen network to hydroxyapatite (HA), the mineral phase of the bone. We synthesized a 6‐glutamic acid sequence in solid phase with affinity to HA crystals via ionic interactions. One end of the synthesized peptide was functionalized with an acrylate group to covalently attach the peptide (Ac‐Glu6) to the aqueous‐based biodegradable and in situ crosslinkable PLEOF hydrogel matrix. To determine the effect of energetic interactions between the fillers and hydrogel matrix, HA nanoparticles were also treated with an acrylate functionalized 6‐glycine amino acid peptide (Ac‐Gly6) that interacts with the fillers only by van der Waals and polar interactions (without ionic interactions). Crosslinked PLEOF/apatite scaffolds were prepared using PLEOF as the degradable macromer, HA nanofillers treated with Ac‐Glu6 peptide linker, and a neutral redox initiation system. The viscoelastic properties were studied by dynamic time sweep, strain sweep, and small amplitude oscillatory rheometry. Composites without surface treatment, treated with Ac‐Gly6, and treated with Ac‐Glu6 at different volume fractions and various particle sizes were examined. The results showed that the 6‐mer glutamic acid sequence significantly affects the shear modulus of the scaffold because of ionic interactions between the peptide and HA crystals. © 2006 Wiley Periodicals, Inc. Biopolymers 85:370–378, 2007.This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Hyrtiosal, a PTP1B Inhibitor from the Marine Sponge Hyrtios erectus, Shows Extensive Cellular Effects on PI3K/AKT Activation, Glucose Transport, and TGFβ/Smad2 Signaling
Authors: Sun Tao , Wang Qi , Yu Zhiguo , Zhang Yu , Guo Yuewei , Chen Kaixian , Shen Xu , Jiang Hualiang 
Published: December 2006

AbstractProtein tyrosine phosphatase 1B (PTP1B) negatively regulates insulin signaling, and PTP1B inhibitors have been seen as promising therapeutic agents against obesity and type 2 diabetes. Here we report that the marine natural product hyrtiosal, from the marine sponge Hyrtios erectus, has been discovered to act as a PTP1B inhibitor and to show extensive cellular effects on PI3K/AKT activation, glucose transport, and TGFβ/Smad2 signaling. This inhibitor wad able to inhibit PTP1B activity in dose‐dependent fashion, with an IC50 value of 42 μM in a noncompetitive inhibition mode. Further study with an IN Cell Analyzer 1000 cellular fluorescence imaging instrument showed that hyrtiosal displayed potent activity in abolishing the retardation of AKT membrane translocation caused by PTP1B overexpression in CHO cells. Moreover, it was found that this newly identified PTP1B inhibitor could dramatically enhance the membrane translocation of the key glucose transporter Glut4 in PTP1B‐overexpressed CHO cells. Additionally, in view of our recent finding that PTP1B was able to modulate insulin‐mediated inhibition of Smad2 activation, hyrtiosal was also tested for its capabilities in the regulation of Smad2 activity through the PI3K/AKT pathway. The results showed that hyrtiosal could effectively facilitate insulin inhibition of Smad2 activation. Our current study is expected to supply new clues for the discovery of PTP1B inhibitors from marine natural products, while the newly identified PTP1B inhibitor hyrtiosal might serve as a potential lead compound for further research.
Nitrosation of N‐Terminally Blocked Tryptophan and Tryptophan‐Containing Peptides by Peroxynitrite
Authors: Peyrot Fabienne , Ducrocq Claire 
Published: December 2006

AbstractTryptophan is known to be a major target of oxidative stress and to take part in electron transfer. In proteins, its fluorescence is extinguished after treatment with oxidative agents, like peroxynitrite (ONOO−/ONOOH)—the product of the reaction of NO. and superoxide anion (O2.−) radicals. The main reactions of N‐blocked tryptophan derivatives (melatonin or N‐acetyl‐L‐tryptophan) exposed to peroxynitrite at physiological pH are oxidation to formylkynuramine or formylkynurenine, respectively, and nitrosation, which leads to substituted 1‐nitrosoindoles. Here we show that peroxynitrite‐induced nitrosation is specific to N‐blocked L‐tryptophan derivatives and is not obtained with free L‐tryptophan. Such a nitrosation can be evaluated by using 4,5‐diaminofluorescein (DAF‐2), which is converted to the fluorescent triazolofluorescein by NO. donors and nitrosating agents. N‐acetyl‐L‐tryptophan was shown to be twice as efficient as melatonin in transferring NO from peroxynitrite to DAF‐2. DAF‐2 responses were then used to assess the ability of a series of L‐tryptophan‐containing peptides to give transient N‐nitrosoindoles upon treatment with peroxynitrite. Many peptides proved not to be susceptible to nitrosation under these conditions. However, the N‐terminally blocked peptide of endothelin‐1 (Ac–Asp–Ile–Ile–Trp) reacted in a very similar fashion to melatonin; this shows that tryptophan residue nitrosation could occur when it was exposed to peroxynitrite.