bluuebunny/crossref_metadata_2025_split huggingface dataset:
Applications of the hazard rate ordering in reliability and order statistics
Authors: Boland Philip J. , El-Neweihi Emad , Proschan Frank 
Published: April 2006

The hazard rate ordering is an ordering for random variables which compares lifetimes with respect to their hazard rate functions. It is stronger than the usual stochastic order for random variables, yet is weaker than the likelihood ratio ordering. The hazard rate ordering is particularly useful in reliability theory and survival analysis, owing to the importance of the hazard rate function in these areas. In this paper earlier work on the hazard rate ordering is reviewed, and extensive new results related to coherent systems are derived. Initially we fix the form of a coherent structure and investigate the effect on the hazard rate function of the system when we switch the lifetimes of its components from the vector (T1, · ··, Tn) to the vector (T′1, · ··, T′n), where the hazard rate functions of the two vectors are assumed to be comparable in some sense. Although the hazard rate ordering is closed under the formation of series systems, we see that this is not the case for parallel systems even when the system is a two-component parallel system with exponentially distributed lifetimes. A positive result shows that for two-component parallel systems with proportional hazards (λ1r(t), λ2r(t))), the more diverse (λ1, λ2) is in the sense of majorization the stronger is the system in the hazard rate ordering. Unfortunately even this result does not extend to parallel systems with more than two components, demonstrating again the delicate nature of the hazard rate ordering.The principal result of the paper concerns the hazard rate ordering for the lifetime of a k-out-of-n system. It is shown that if τ k|n is the lifetime of a k-out-of-n system, then τ k|n is greater than τ k+1|n in the hazard rate ordering for any k. This has an interesting interpretation in the language of order statistics. For independent (not necessarily identically distributed) lifetimes T1, · ··, Tn, we let Tk:n represent the kth order statistic (in increasing order). Then it is shown that Tk +1:n is greater than Tk:n in the hazard rate ordering for all k = 1, ···, n − 1. The result does not, however, extend to the stronger likelihood ratio order.
Poly(3,4‐alkylenedioxypyrroles): The PXDOPs as Versatile Yet Underutilized Electroactive and Conducting Polymers
Authors: Walczak R. M. , Reynolds J. R. 
Published: April 2006

AbstractThe poly(3,4‐dioxypyrrole) (PXDOP) family of conducting and electroactive polymers has now been developed to the point that multiple synthetic routes allow many functionalized polymers with controllable optoelectronic and redox properties. These properties, which include high conductivity, multicolor cathodic and anodic electrochromism, and rapid redox switching, allow these materials to be used in a variety of applications that potentially include conducting coatings, electrochromic windows and displays, chemical sensors, bioactive materials, and mechanical actuators. Surprisingly, the scientific literature published on the PXDOP derivatives has been isolated and sparse compared to that of other conducting polymers. This report will highlight the synthesis and materials properties of PXDOPs and show how these powerful materials fit into the frontier of conducting polymers research.
Enantiomeric separation of mineralocorticoid receptor (hMR) antagonists using the Chiralcel® OJ‐H HPLC column with novel polar cosolvent eluent systems
Authors: Sharp V. Scott , Kennedy Joseph H. , Belvo Matthew D. , Williams Jeffrey D. , Risley Donald S. , Seest Eric P. 
Published: April 2006

AbstractThis study demonstrates the increased versatility of the Chiralcel® OJ‐H stationary phase when using various alcohol/acetonitrile mobile phases. This chiral stationary phase has traditionally been employed in the normal phase mode and more recently with neat alcohols as eluents. Selected isomeric human mineralocorticoid receptor (hMR) antagonist pharmaceutical candidates and synthetic intermediates were separated using the Chiralcel® OJ‐H HPLC column with novel polar cosolvent eluent systems. The capacity factors, resolution, and selectivity of the chiral separations were assessed while varying the alcohol/acetonitrile composition and alcohol identity. The mixed polar eluents provide separations that are nearly always superior to both the traditional hexane‐rich and single‐alcohol “polar organic” eluents for the compounds tested in this article. Chirality, 2006. © 2006 Wiley‐Liss, Inc.
Exenatide elicits sustained glycaemic control and progressive reduction of body weight in patients with type 2 diabetes inadequately controlled by sulphonylureas with or without metformin
Authors: Riddle Matthew C. , Henry Robert R. , Poon Terri H. , Zhang Bei , Mac Susanna M. , Holcombe John H. , Kim Dennis D. , Maggs David G. 
Published: April 2006

AbstractBackgroundIn two placebo‐controlled 30‐week trials, treatment with exenatide reduced HbA1c and body weight in patients with type 2 diabetes in the context of sulphonylurea (SU) or SU plus metformin (MET) as background treatment. This analysis examines the effects of 82 weeks of exenatide treatment for participants in these earlier 30‐week trials.MethodsData were pooled from the two pivotal trials of exenatide added to SU or SU plus MET. Both 30‐week, placebo‐controlled trials of 5 µg or 10 µg exenatide b.i.d. were followed by 52‐week open‐label, uncontrolled extension studies in which all participants received 10 µg exenatide b.i.d. and continued prior oral therapies. This interim analysis includes data for 222 patients who completed 82 weeks of exenatide treatment (61% M, age 57 ± 10 y, weight 99 ± 21 kg, BMI 34 ± 6 kg/m2, HbA1c8.4 ± 1.0% [mean ± SD]).ResultsReduction in HbA1c from baseline to week 30 (−0.8 ± 0.1% and −1.0 ± 0.1% for 5 µg b.i.d. and 10 µg b.i.d., respectively [mean ± SE]) was sustained up to week 82 (−1.0 ± 0.1%). Of 207 patients with baseline HbA1c > 7%, 44% achieved HbA1c ≤ 7% at week 82. Reduction of body weight from baseline to week 30 (−1.4 ± 0.3 kg and −2.1 ± 0.3 kg for 5 µg b.i.d. and 10 µg b.i.d., respectively) was progressive up to week 82 (−4.0 ± 0.3 kg). The most frequent adverse events were nausea and hypoglycaemia, both generally mild to moderate in intensity.ConclusionsExenatide added to maximally effective doses of SU or SU plus MET resulted in a sustained reduction in HbA1c and a progressive reduction in weight over $\def\qdr#1#2{\begingroup\hbox{\raise0.3em\hbox{$\scriptstyle #1$}$\!{/}\!$\lower0.2em\hbox{$\scriptstyle #2$}}\endgroup}1\qdr{1}{2}$ years. Copyright © 2006 John Wiley & Sons, Ltd.
Determination of tobacco‐specific N‐nitrosamines in rabbit serum by capillary zone electrophoresis and capillary electrophoresis‐electrospray ionization‐mass spectrometry with solid‐phase extraction
Authors: Li Chenchen , Chen Zheng , Wen Dawei , Zhang Jianxun , Cong Weihong , Yu Bing , Liao Yiping , Liu Huwei 
Published: April 2006

AbstractIn this paper, we propose a new strategy for separation and determination of tobacco‐specific N‐nitrosamines (TSNAs), a group of strong carcinogens found only in tobacco products, by using CZE and CE‐MS associated with SPE. Six TSNAs: N'‐nitrosonornicotine, N'‐nitrosoanatabine, N'‐nitrosoanabasine, 4‐(methylnitrosamino)‐1‐(3‐pyridyl)‐1‐butanone, 4‐(methylnitrosamino)‐1‐(3‐pyridyl)‐1‐butanol, and 4‐(methylnitrosamino)‐4‐(3‐pyridyl)‐1‐butanol were simultaneously separated by either of two CZE methods, one of which worked with ammonium formate buffer (pH 2.5) and another with citrate buffer (pH 2.4), as well as a CE‐MS method. The CZE conditions including pH and concentration of running buffer, capillary length, applied voltage, and capillary temperature were systematically optimized. For CE‐MS method, an optimized sheath liquid consisted of methanol–water was used at a flow rate of 10 μL/min. With SPE procedure, our proposed CE‐MS method was successfully applied to determine TSNAs after 15 min metabolism in rabbits. A comparison study between CZE and CE‐MS methods for quantitative purposes was carried out, showing that both methods provided similar separation efficiency, selectivity, repeatability, linearity, and recovery. However, CE‐MS method was better suited for the analysis of TSNAs in complicated biological samples for its sensitivity and extra information on molecular structure. Having good accordance with our previous work by using LC‐MS, the new CE‐MS method is expected to be an alternative to the LC‐MS method and applied to study the metabolism of TSNAs.
Assessing the geochemical reactivity of inorganic phosphorus along estuaries by means of laboratory simulation experiments
Authors: García‐Luque Enrique , Forja Pajares Jesús M. , Gómez‐Parra Abelardo 
Published: April 2006

AbstractPhosphate behaviour in natural estuarine systems can be studied by performing field measurements and by undertaking laboratory simulation experiments. Thus, in this paper we describe the use of a dynamic automated estuarine simulator to characterize the geochemical reactivity of phosphate in varying salinity gradients in order to study possible mechanisms of phosphate removal from the dissolved phase (e.g. formation of some kind of apatite) and how changes in pH and salinity values influence this removal. Six laboratory assays, representing various salinity and pH gradients (average pH values between 7 and 8), were carried out. The geochemical equilibrium model MINTEQA2 was employed to characterize removal of phosphate. Among the minerals from which dissolved phosphate can originate, it seems that hydroxyapatite is by far the mineral that shows the greatest saturation indexes in the experiments. Thus, there is evidence that a type of calcium phosphate (hydroxyapatite) is involved in phosphate removal in the assays. Phosphate removal by Ca2+ occurs sharply at salinity values of 1–2, whereas by Fe3+ it is relatively gradual, at least until a salinity value of 7. Copyright © 2006 John Wiley & Sons, Ltd.
Comparison of impacts of dams on the annual maximum flow characteristics in three regulated hydrologic regimes in Québec (Canada)
Authors: Assani Ali A. , Stichelbout Émilie , Roy André G. , Petit François 
Published: April 2006

AbstractDespite the presence of numerous dams in Québec, no study has yet been devoted to their impacts on flood levels. To compensate for this deficiency, we have compared the impacts of dams on the five characteristics (magnitude and its interannual variability, timing and its interannual variability, and asymmetry) of the maximum annual flows between natural rivers and regulated rivers by means of several statistical approaches (analysis of variance, chi‐square test, nonparametric tests, etc.). In the course of this study, we analysed 88 stations on pristine rivers and 60 stations on regulated rivers. The latter group was subdivided into three regulated hydrologic regimes, i.e. inversed flow regimes (25 stations), homogenization flow regimes (15 stations) and natural‐type flow regimes (20 stations). The following observations emerge from this study. (1) In inversed and homogenization flow regimes, generally associated with reservoirs, all the flow characteristics are modified. These modifications notably entrain a decrease in magnitude, a significant reduction in the frequency of the maximum annual spring flows when the snow is melting and an increase in skewness of the distribution and interannual variability of the magnitude and dates of occurrence of the annual maximum flows. We also observed the disappearance of most flows with a recurrence of over 10 years. All these changes particularly affect watersheds larger than 10 000 km2. (2) In natural‐type flow regimes, often associated with run‐of‐river dams, very few changes were observed compared with pristine rivers. These changes primarily affected watersheds smaller than 1000 km2. Copyright © 2006 John Wiley & Sons, Ltd.
Possible role of duration of PKC‐induced ERK activation in the effects of agonists and phorbol esters on DNA synthesis in panc‐1 cells
Authors: Rácz Gábor Z. , Szűcs Ákos , Szlávik Vanda , Vág János , Burghardt Beáta , Elliott Austin C. , Varga Gábor 
Published: April 2006

AbstractProtein kinase C (PKC) and extracellular signal‐regulated kinase (ERK) have been implicated in the effects of regulatory peptides on proliferation. We studied how ERK was activated by PKC following regulatory peptide or phorbol ester stimulation and we also investigated the effect of ERK activation on proliferation in Panc‐1 cells. Panc‐1 cells transfected with CCK1 receptors were treated with cholecystokinin (CCK), neurotensin (NT), or phorbol 12‐myristate 13‐acetate (PMA). DNA synthesis was studied by measuring tritiated thymidine incorporation. PKC isoforms were selectively inhibited with Gö6983 and 200 nM Ro‐32‐0432, their translocation was detected by confocal microscopy and by subcellular fractionation followed by immunoblotting. ERK cascade activation was detected with phosphoERK immunoblotting and inhibited with 20 µM PD98059. PMA and CCK inhibited, NT stimulated DNA synthesis. These effects were inhibited by Ro‐32‐0432 but not by Gö6983 suggesting the involvement of PKCε in proliferation control. Confocal microscopy and subcellular fractionation demonstrated that PMA, CCK, and NT caused cytosol to membrane translocation of PKCε and ERK activation that was inhibited by Ro‐32‐0432 but not by Gö6983. ERK activation was prolonged following PMA and CCK, but transient after NT treatment. PMA, CCK, and NT all activated cyclinD1, while p21CIP1 expression was increased by only PMA and CCK, but not by NT; each of these effects is inhibited by PD98059. In conclusion, our results provide evidence for PKCε‐mediated differential ERK activation and growth regulation in Panc‐1C cells. Identification of the mechanisms by which these key signaling pathways are modulated could provide a basis for the development of novel therapeutic interventions to treat pancreatic cancer. J. Cell. Biochem. © 2006 Wiley‐Liss, Inc.
Enrichment of NRBC in maternal blood: a more feasible method for noninvasive prenatal diagnosis
Authors: Purwosunu Yuditiya , Sekizawa Akihiko , Farina Antonio , Okai Takashi , Takabayashi Haruo , Wen Peng , Yura Hirofumi , Kitagawa Michihiro 
Published: April 2006

AbstractObjectiveTo assess the efficiency and reliability of the separation of fetal nucleated red blood cells (NRBCs) using the galactose‐specific lectin method, we counted the number of NRBCs in the blood of pregnant women at various gestational ages, as well as after amniocentesis and termination.MethodPeripheral blood samples were obtained from (1) 22 singleton pregnant women (between 9 and 34 weeks of gestation) and from 23 women who underwent termination (between 6 and 19 weeks of gestation). To determine whether amniocentesis influences numbers of NRBCs, five samples were obtained (2) before and after the procedure. NRBC enrichment was initially performed using density gradients and subsequently using galactose‐specific lectin. The cells were then stained with May‐Gruenwald Giemsa (MGG) and counted under a light microscope.ResultsNRBCs were found in all samples, ranging from 1 to 82 (median = 12.5 cells/sample). The multiples of the median (MoM) conversion of the number of cells revealed a raise of 1.66‐fold (0.12–6.64) in post‐termination samples compared with the control value of 1.00 MoM (0.11–6.92; p = 0.036). The postamniocentesis increase was, instead, 1.11‐fold (0.17–4.02), which did not reach statistical significance.ConclusionAll blood samples tested contained NRBCs. Samples obtained after termination yielded more cells than those obtained from women whose pregnancies were going on normally. The number of NRBCs in post‐termination samples after MoM conversion differed significantly from those in controls. Although separation of NRBCs was not feasible due to extremely low numbers, our results indicated that NRBCs are detectable in all blood samples from normal pregnant women. Copyright © 2006 John Wiley & Sons, Ltd.
On the in‐situ polymerization of cyclic butylene terephthalate oligomers: DSC and rheological studies
Authors: Ishak Z.A. Mohd , Gatos K.G. , Karger‐Kocsis J. 
Published: April 2006

AbstractThe thermal and rheological behaviors of cyclic butylene terephthalate (CBT) were studied with differential scanning calorimetry (DSC) and plate–plate rheometry, respectively. DSC scans were taken at different heating rates. The related first‐heat thermograms indicated crystallization and melting of the resulting poly (butylene terephthalate) (PBT) only at very low heating rate (0.5°C/min). As the crystallization and melting enthalpies were closely matched, one could conclude that the polymerization is essentially athermic. The polymerization was accompanied by a steep increase of the melt viscosity in isothermal rheological tests performed in the temperature range T = 145–210°C. Changes in the viscoelasticity of the polymerizing CBT and crystallizing PBT could be best followed by considering the changes in the phase angle. Viscosity increased with the conversion exponentially in the first approximation. POLYM. ENG. SCI., 46:743–750, 2006. © 2006 Society of Plastics Engineers
Proteome analysis of rice uppermost internodes at the milky stage
Authors: Yang Pingfang , Liang Yu , Shen Shihua , Kuang Tingyun 
Published: April 2006

AbstractUppermost internodes, which connect the part between the ear and lower stem, form an important pathway transporting mineral nutrition from roots and photosynthates from leaves (especially the flag leaf) to the ear. The milky stage is the first stage of seed ripening. The uppermost internodes of rice at the milky stage are critical for seed quality and yield. Total soluble proteins of the uppermost internodes of rice (Oryza sativa L. ssp. indica) at the milky stage were analyzed using proteomic methods. Using 2‐DE, 762 reproducible protein spots were detected. Among them, 132 abundant proteins were analyzed using MALDI‐TOF‐MS. Searching in the National Center for Biotechnology Information database, we could identify 98 proteins, which represent 80 gene products. These proteins belong to 11 functional groups with energy production‐associated proteins in the first place. The large accumulation of proteins involved in metabolism, signaling, and stress resistance indicated that the uppermost internodes of rice have a high physiological and stress‐resistant activity. In addition, our results will also enrich the database of the rice proteome.
Synthesis and application as polymer electrolyte of hyperbranched polyether made by cationic ring‐opening polymerization of 3‐{2‐[2‐(2‐hydroxyethoxy)ethoxy]ethoxymethyl}‐3′‐methyl‐oxetane
Authors: Lin Ye , Zeng‐Guo Feng , Yu‐Mei Zhao , Feng Wu , Shi Chen , Guo‐Qing Wang 
Published: April 2006

AbstractA novel cyclic ether monomer 3‐{2‐[2‐(2‐hydroxyethoxy)ethoxy]ethoxy‐methyl}‐3′‐methyloxetane (HEMO) was prepared from the reaction of 3‐hydroxymethyl‐3′‐methyloxetane tosylate with triethylene glycol. The corresponding hyperbranched polyether (PHEMO) was synthesized using BF3·Et2O as initiator through cationic ring‐opening polymerization. The evidence from 1H and 13C NMR analyses revealed that the hyperbranched structure is constructed by the competition between two chain propagation mechanisms, i.e. active chain end and activated monomer mechanism. The terminal structure of PHEMO with a cyclic fragment was definitely detected by MALDI‐TOF measurement. A DSC test implied that the resulting polyether has excellent segment motion performance potentially beneficial for the ion transport of polymer electrolytes. Moreover, a TGA assay showed that this hyperbranched polymer possesses high thermostability as compared to its liquid counterpart. The ion conductivity was measured to reach 5.6 × 10−5 S/cm at room temperature and 6.3 × 10−4 S/cm at 80 °C after doped with LiTFSI at a ratio of Li:O = 0.05, presenting the promise to meet the practical requirement of lithium ion batteries for polymer electrolytes. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3650–3665, 2006
Electrospinning of neat and laponite‐filled aqueous poly(ethylene oxide) solutions
Authors: Daga Vikram K. , Helgeson Matthew E. , Wagner Norman J. 
Published: April 2006

AbstractElectrospinning is reported for viscoelastic aqueous solutions of poly(ethylene oxide) (PEO) and with added nanoclay (laponite). A weak correlation between fiber diameter and the spinning solution's zero‐shear viscosity is observed and compared with previous work reported by McKee et al. (McKee et al., Macromolecules 2004, 37, 1760). A new analysis of electrospinning results for PEO indicates a universal correlation between fiber diameter and solution properties that does not include shear viscosity as a primary variable. The addition of laponite nanoclay to the PEO solutions, which has been previously shown to result in rheologically simple solutions, leads to different fiber morphologies for the same shear viscosity in contradiction with reports for titania particles (Drew et al., J Macromol Sci Part A: Pure Appl Chem 2003, 40, 1415). The research identifies additional physicochemical properties that are important in determining electrospun fiber morphology. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1608–1617, 2006
The impact of diagnosis and plaque radiotherapy treatment of malignant choroidal melanoma on patients' quality of life
Authors: Reimer Jens , Voigtlaender‐Fleiss Anja , Karow Anne , Bornfeld Norbert , Esser Joachim , Helga Franke Gabriele 
Published: April 2006

AbstractQuality of life (QOL) has become an important outcome criterion of medical interventions, but the impact of diagnosis and radiotherapy on QOL in patients with malignant choroidal melanoma (MCM) has rarely been studied. Inventories covering global (SF‐36) and disease‐specific QOL (NEI‐VFQ), mental distress (SCL‐90‐R), and social support (K‐22, German) were applied to a consecutive sample of MCM‐patients scheduled for plaque radiotherapy. Data were gathered preoperatively (t0) and 3 months postoperatively (t1, except for the K‐22, which was applied at t0 only). Fifty‐four patients took part in both surveys, the number of patients with visual impairment increased from 21 preoperatively to 34 postoperatively. Global QOL of MCM‐patients was significantly reduced compared to the healthy norm and other ophthalmological patients both at t0 and t1. Clinically relevant distress was present in every second patient at t0 and every third patient at t1, social support was not impaired. Global and disease‐specific QOL declined significantly from t1 to t0. The MCM diagnosis compromises QOL, which is additionally impaired by radiotherapy. Regular QOL assessment can help to identify patients at risk, facilitate provision of psychosocial treatment and may thus improve patient satisfaction. Copyright © 2006 John Wiley & Sons, Ltd.
Multi‐determinant trial functions in the determination of the dissociation energy of the beryllium dimer: Quantum Monte Carlo study
Authors: Harkless J. A. W. , Irikura K. K. 
Published: April 2006

AbstractBoth variational Monte Carlo (VMC) and fixed‐node diffusion Monte Carlo (DMC) are used to estimate the dissociation energy of Be2. The effect of using single‐ and multi‐reference trial functions on the quality of the Monte Carlo estimates is investigated, with independent‐particle wave functions ranging from a restricted Hartree–Fock (RHF) calculation up to a complete active space self‐consistent field (CASSCF) with four valence electrons in 12 active orbitals. It was determined that the best trial function for DMC had a high cutoff for inclusion and included all 2s and 2p orbitals in a CASSCF(4,8) calculation. The best DMC estimate, De = 829(64) cm−1, compares well with the experimental value of 839(10) cm−1 but is lower than values from the best basis‐set calculations. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006