bluuebunny/crossref_metadata_2025_split huggingface dataset:
Aeration optimization of a wastewater treatment plant using genetic algorithm
Authors: Holenda B. , Domokos E. , Rédey Á. , Fazakas J. 
Published: February 2007

AbstractThis paper discusses the aeration optimization problem of an intermittently aerated wastewater treatment plant by the application of a stochastic optimization approach, genetic algorithm (GA). In this process, the alternating aerobic and anoxic conditions needed for nitrogen removal are realized in a single basin by switching the aeration sequentially on and off. Since the operation of these plants may be challenging both for economical and technical reasons, several previous studies have investigated the possibility of reduction of the operating cost, however, it turned out that for long‐term application these methods can save only limited per cent of the cost. Furthermore, these investigations also had to make problem simplifications in order to use optimization methods which usually need significant computational effort to give—only a local optimum—of the problem. The objective of this paper is to demonstrate an optimization procedure to minimize the pollution load in the receiving water body, rather than the operational cost, using a complete model of the treatment process. The results were evaluated based on rigorous evaluation criteria and showed that using GA‐based optimization strategy an optimal solution can be efficiently found where both pollution load and energy consumption savings can reach up to 10% compared to traditional control strategies. Copyright © 2007 John Wiley & Sons, Ltd.
Parametric uncertainty and disturbance attenuation in the suboptimal control of a non‐linear electrochemical process
Authors: Costanza Vicente 
Published: February 2007

AbstractThe optimal control of the hydrogen evolution reactions is attempted for the regulation and change of set‐point problems, taking into account that model parameters are uncertain and I/O signals are corrupted by noise. Bilinear approximations are constructed, and their dimension eventually increased to meet accuracy requirements with respect to the trajectories of the original plant. The current approximate model is used to evaluate the optimal feedback through integration of the Hamiltonian equations. The initial value for the costate is found by solving a state‐dependent algebraic Riccati equation, and the resulting control is then suboptimal for the electrochemical process. The bilinear model allows for an optimal Kalman–Bucy filter application to reduce external noise. The filtered output is reprocessed through a non‐linear observer in order to obtain a state‐estimation as independent as possible from the bilinear model. Uncertainties on parameters are attenuated through an adaptive control strategy that exploits sensitivity functions in a novel fashion. The whole approach to this control problem can be applied to a fairly general class of non‐linear continuous systems subject to analogous stochastic perturbations. All calculations can be handled on‐line by standard ordinary differential equations integration software. Copyright © 2007 John Wiley & Sons, Ltd.
Effect of clay exfoliation and organic modification on morphological, dynamic mechanical, and thermal behavior of melt‐compounded polyamide‐6 nanocomposites
Authors: Mohanty Smita , Nayak Sanjay K. 
Published: February 2007

AbstractPolyamide‐6/clay nanocomposites were prepared employing melt bending or compounding technique followed by injection molding using different organically modified clays. X‐ray diffraction and transmission electron microscopy were used to determine the molecular dispersion of the modified clays within the matrix polymer. Mechanical tests revealed an increase in tensile and flexural properties of the matrix polymer with the increase in clay loading from 0 to 5%. C30B/polyamide‐6 nanocomposites exhibited optimum mechanical performance at 5% clay loading. Storage modulus of polyamide‐6 also increased in the nanocomposites, indicating an increase in the stiffness of the matrix polymer with the addition of nanoclays. Furthermore, water absorption studies confirmed comparatively lesser tendency of water uptake in these nanocomposites. HDT of the virgin matrix increased substantially with the addition of organically modified clays. DSC measurements revealed both γ and α transitions in the matrix polymer as well as in the nanocomposites. The crystallization temperature (Tc) exhibited an increase in case of C30B/polyamide‐6 nanocomposites. Thermal stability of virgin polyamide‐6 and the nanocomposites has been investigated employing thermogravimetric analysis. POLYM. COMPOS., 28:153–162, 2007. © 2007 Society of Plastics Engineers
Managing appearance changes resulting from cancer treatment: resilience in adolescent females
Authors: Wallace Melissa L. , Harcourt Diana , Rumsey Nichola , Foot Annabel 
Published: February 2007

AbstractTypically, adolescence is marked by cognitive and physical developments impacting on self‐esteem, independence and sexual awareness, often resulting in increased appearance awareness and dissatisfaction. Adolescents with cancer have the additional burden of illness, treatments and resultant appearance changes. This study aimed to explore the impact of these changes on adolescents who have had cancer. In depth, semi‐structured interviews were conducted with six females between 14 and 19 years who had completed treatment within the previous two years, and analysed using Interpretative Phenomenological Analysis (IPA). Concerns around an altered appearance were significant during treatment, serving as a constant reminder of ‘difference’ and a marker of illness. However, since treatment, participants expressed an apparent shift in views and expectations of their appearance, as well as the value placed on it—expressing increased satisfaction with their own appearance and a decrease in its importance. While important to acknowledge the distress and challenges experienced by participants, results highlight the need for research and care to focus on positive experiences of patients, rather than simply maladjustment. Explanations for the findings are explored, including the temporary nature of many appearance changes and the life‐threatening nature of cancer. Copyright © 2007 John Wiley & Sons, Ltd.
Quantitative high‐throughput determination of endogenous retinoids in human plasma using triple‐stage liquid chromatography/tandem mass spectrometry
Authors: Gundersen Thomas E. , Bastani Nasser E. , Blomhoff Rune 
Published: February 2007

AbstractA high‐throughput ultrasensitive analytical method based on liquid chromatography with positive ion atmospheric pressure chemical ionization (APCI) coupled to tandem mass spectrometric detection (LC/MS/MS) was developed for the determination of all‐trans‐4‐oxo‐retinoic acid (at4oxoRA), 13‐cis‐4‐oxo‐retinoic acid (13c4oxoRA), 13‐cis‐retinoic acid (13cRA), all‐trans‐retinoic acid (atRA) and all‐trans‐retinol (atROH) in human plasma. A stable isotope of atRA was used as internal standard (IS). The analytes and IS were isolated from 100 µL plasma by acetonitrile mono‐phase extraction (MPE) performed in black 96‐well microtiterplates. A 100 µL injection was focused on‐column and chromatographed on an Agilent ZORBAX SB‐C18 rapid‐resolution high‐throughput (RRHT) column with 1.8‐µm particles (4.6 mm × 50 mm) maintained at 60°C. The initial mobile phase composition was acetonitrile/water/formic acid (10:90:0.1, v/v/v) delivered at 1.8 mL/min. Elution was accomplished by a fast gradient to acetonitrile/methanol/formic acid (90:10:0.1, v/v/v). The method had a chromatographic total run time of 7 min. An Applied Biosystems 4000 Q TRAP linear tandem mass spectrometer equipped with a heated nebulizer (APCI) ionization source was operated in multiple reaction monitoring (MRM) mode with the precursor‐to‐product ion transitions m/z 315.4 → 297 (4‐oxo‐retinoic acids), 301.2 → 205 (retinoic acids), 305.0 → 209 (IS) and 269.2 → 93 (retinol) used for quantification. The assay was fully validated and found to have acceptable accuracy, precision, linearity, sensitivity and selectivity. The mean extraction recoveries from spiked plasma samples were 80–105% for the various retinoids at three different levels. The intra‐day accuracy of the assay was within 8% of nominal and intra‐day precision was better than 8% coefficient of variance (CV) for retinoic acids. Inter‐day precision results for quality control samples run over a 12‐day period alongside clinical samples showed mean precision better than 12.5% CV. The limit of quantification was in the range of 0.1–0.2 ng/mL and the mass limit of detection (mLOD) was in the range 1–4 pg on column for the retinoic acids. The assay has been successfully applied to the analysis of 1700 plasma samples. Copyright © 2007 John Wiley & Sons, Ltd.
Liquid chromatography/tandem mass spectrometry determination of (4S,2RS)‐2,5,5‐trimethylthiazolidine‐4‐carboxylic acid, a stable adduct formed between D‐(–)‐penicillamine and acetaldehyde (main biological metabolite of ethanol), in plasma, liver and brain rat tissues
Authors: Serrano Elena , Pozo Oscar J. , Beltrán Joaquin , Hernández Felix , Font Laura , Miquel Marta , Aragon Carlos M. G. 
Published: February 2007

AbstractAcetaldehyde, the main biological metabolite of ethanol, is nowadays considered to mediate some ethanol‐induced effects. Previous studies on alcohol effect attenuation have shown that D‐(–)‐penicillamine (3‐mercapto‐D‐valine), a thiol amino acid, acts as an effective agent for the inactivation of acetaldehyde. In the study reported here, laboratory rats were treated with ethanol and D‐(–)‐penicillamine at different doses looking for the interaction (in vivo) of D‐(–)‐penicillamine with metabolically formed acetaldehyde following a condensation reaction to form the stable adduct (4S,2RS)‐2,5,5‐trimethylthiazolidine‐4‐carboxylic acid (TMTCA). A novel and rapid procedure based on liquid chromatography coupled to tandem mass spectrometry (LC/MS/MS) was developed for quantification and reliable identification of TMTCA in different rat tissues, including plasma, liver and brain. Firstly, plasma was obtained from whole blood. Then, proteins were precipitated from plasma, brain and liver extracts with acetonitrile and the clarified extracts diluted 10‐fold. A 20 µL aliquot of the final extracts was then analyzed using an Atlantis C18 5 µm, 100 × 2 mm column which was connected to the electrospray source of a LC/triple quadrupole mass spectrometer. The analyte was detected in positive ion mode acquiring four MS/MS transitions in selected reaction monitoring (SRM) mode.The method has been validated and it has proved to be fast, reliable and sensitive. The accuracy and precision were evaluated by means of recovery experiments from plasma, liver and brain samples fortified at two concentration levels obtaining satisfactory recoveries in all cases: 95 and 105% in plasma (at 10 and 100 ng/mL, respectively), 79 and 89% in brain (100 and 1000 ng/g), 85 and 99% in liver (100 and 1000 ng/g). Precision, expressed as repeatability, was in all tissues analyzed lower than 17% at the two concentrations tested. The estimated detection limits were 1 ng/mL in plasma, 4 ng/g in brain and 5 ng/g in liver. The limit of quantitation objective (the lowest concentration that was validated with acceptable results) was set up at 10 ng/mL for plasma and 100 ng/g for brain and liver tissue.The reliable identification of the analyte was ensured by the acquisition of four transitions and by their ion abundance ratio measurement. Due to its excellent selectivity and sensitivity, the method developed in this work provides an excellent tool for the specific determination of this cyclic amino acid in biological samples. Copyright © 2007 John Wiley & Sons, Ltd.
Understanding the influence of post‐excite radius and axial confinement on quantitative proteomic measurements using Fourier transform ion cyclotron resonance mass spectrometry
Authors: Frahm Jennifer L. , Velez Coral M. Capo , Muddiman David C. 
Published: February 2007

AbstractEarly studies of Fourier transform ion cyclotron resonance (FT‐ICR) mass spectrometry (MS) explored many of the fundamental issues surrounding the potential of the technique to provide quantitative data. Improvements in instrument technology and the analysis of larger molecules in increasingly complex mixtures warrant not only a revisit to some of these earlier studies, but a more comprehensive examination of the influence of various instrument parameters on quantitative (absolute and relative) measurements in proteomics. We present a detailed examination of the role that acquisition time, excite voltage (i.e. excite radius), trapping voltage, and the type of excitation waveform have on the ability of FT‐ICR to accurately quantify biological molecules. The use of a stable‐isotope‐labeled and unlabeled phenyl isocyanate derivatized peptide allows us to ascribe the effects of FT‐ICR‐MS on quantification, thus eliminating the contribution of ionization differences to ion abundance. To adequately assess the multiple parameters in the large dataset, we develop a multiplicative quality factor that encompasses the total ion abundance, as well as the accuracy and the precision of abundance ratios. This assessment allows facile determination of optimal instrument parameters for quantitative measurements. Copyright © 2007 John Wiley & Sons, Ltd.
The isoperimetric constant of the random graph process
Authors: Benjamini Itai , Haber Simi , Krivelevich Michael , Lubetzky Eyal 
Published: February 2007

AbstractThe isoperimetric constant of a graph G on n vertices, i(G), is the minimum of $|\partial S| \over |S|$, taken over all nonempty subsets S ⊂ V (G) of size at most n/2, where ∂S denotes the set of edges with precisely one end in S. A random graph process on n vertices, $\tilde{G}(t)$, is a sequence of $n \choose 2$ graphs, where $\tilde{G}(0)$ is the edgeless graph on n vertices, and $\tilde{G}(t)$ is the result of adding an edge to $\tilde{G}(t-1)$, uniformly distributed over all the missing edges. The authors show that in almost every graph process $i(\tilde{G}(t))$ equals the minimal degree of $\tilde{G}(t)$ as long as the minimal degree is o(log n). Furthermore, it is shown that this result is essentially best possible, by demonstrating that along the period in which the minimum degree is typically Θ(log n), the ratio between the isoperimetric constant and the minimum degree falls from 1 to $1\over 2$, its final value. © 2007 Wiley Periodicals, Inc. Random Struct. Alg., 2008
Regenerative pseudo‐noise (PN) ranging sequences for deep‐space missions
Authors: Massey James L. , Boscagli Giovanni , Vassallo Enrico 
Published: February 2007

AbstractSpace Agencies are currently considering replacing conventional ranging systems with regenerative schemes for future demanding interplanetary missions. The Consultative Committee for Space Data Systems (CCSDS) in charge of standardization among Space Agencies is studying both Pseudo‐Noise (PN) and Pseudo‐Noise‐Like (PNL) sequences and is due to generate a recommended standard (Blue Book) by 2007. The present paper treats the PN schemes under consideration by CCSDS, which include the weighted‐voting Tausworthe PN ranging scheme and the balanced weighted‐voting Tausworthe PN ranging scheme. Copyright © 2007 John Wiley & Sons, Ltd.
Performance, conformance and change: towards a sustainable tourism strategy for Scotland
Authors: Macleod Calum , Todnem By Rune 
Published: February 2007

AbstractThis article examines the development of a sustainable tourism strategy for Scotland. It outlines conceptual features associated with sustainable tourism and considers the evolving public policy context for sustainable tourism in Scotland. Relevant aspects of recently published strategy documents are reviewed. Public policy implementation and change management theory is used to identify variables and situational contexts likely to influence the evolution of a Scottish sustainable tourism strategy and perceptions of strategy success. The article concludes that future strategy development will be best served by securing implementation performance instead of implementation conformance and explains why this should be the case. Finally, recommendations are made for future strategy development. Copyright © 2007 John Wiley & Sons, Ltd and ERP Environment.
On modelling metabolism‐based biomarkers of exposure: a comparative analysis of nonlinear models with few repeated measurements
Authors: Johnson Brent A. , Rappaport Stephen M. 
Published: February 2007

AbstractEstablishing and characterizing exposure–biomarker relationships is an important problem in molecular epidemiology. The problem is difficult due to several complicating features, namely, the biomarker response is a nonlinear function of exposure and unknown parameters; variation in exposure and biomarker levels occurs both within and between subjects; and errors tend to be heteroscedastic. To overcome some of the statistical challenges in analysing such data, it is common for the investigator to make several assumptions about the data structure. For example, it is common to assume that the natural logarithm of right‐skewed, biomarker measurements lead to homoscedasicity and normality so the effect of outliers is minimized and Gauss–Markov theory is applicable. In this paper, we compare a lognormal maximum likelihood estimator (MLE) to generalized estimating equations (GEE) for drawing statistical inference in a nonlinear model of a benzene biomarker (benzene oxide–albumin adducts) as a function of benzene exposure. We explore the characteristic properties of the lognormal MLE under a certain type of model misspecification and compare its small sample performance to the estimating equation approach in simulation studies. We show that the multiplicative lognormal model can lead to severe biases for modest deviations from the true outcome (biomarker) distribution. Furthermore, the lognormal MLE can exhibit very poor small sample properties even under the true model. All methods are applied in a novel data analysis from a study of benzene‐exposed workers in China. Copyright © 2007 John Wiley & Sons, Ltd.
Bayesian methods for searching for optimal rules for timing intercourse to achieve pregnancy
Authors: Scarpa Bruno , Dunson David B. 
Published: February 2007

AbstractWith societal trends towards increasing age at starting a pregnancy attempt, many women are concerned about achieving conception before the onset of infertility, which precedes menopause. Couples failing to conceive a pregnancy within 12 months are classified as clinically infertile, and may be recommended for assisted reproductive therapy (ART). Because many ART procedures are expensive and may convey an increased risk of adverse outcomes for the offspring, it is advantageous to decrease time to pregnancy by natural methods. One possibility is to intentionally time intercourse during the days of the menstrual cycle having the highest conception probabilities. This article proposes a Bayesian decision theoretic approach for searching for optimal rules for timing intercourse based on cycle day, secretions and other information. Good rules result in high conception probabilities while requiring minimal targeted intercourse. A biologically based statistical model is used to relate cycle day and biomarkers to the conception probability. A stochastic search procedure is then developed to search for rules with high expected utility, and the methods are applied to data from a recent Italian study. Copyright © 2007 John Wiley & Sons, Ltd.
Parasites as heavy metal bioindicators in the shark Carcharhinus dussumieri from the Persian Gulf
Authors: MALEK M. , HASELI M. , MOBEDI I. , GANJALI M. R. , MacKENZIE K. 
Published: February 2007

SUMMARYIn this study the lead and cadmium concentrations in the liver, intestine, muscle and gonad of the shark Carcharhinus dussumieri and its parasites, Anthobothrium sp. and Paraorigmatobothrium sp. (Cestoda), were measured and compared. Tissue samples were collected from Iranian coastal waters of the Persian Gulf. After tissue preparation, the cadmium and lead concentrations were analysed using the Inductively Coupled Plasma technique. The results revealed that lead and cadmium concentrations in both parasite species were many times higher than in the host tissues. The results strongly support the view that helminth parasites are extremely sensitive early warning bioindicators, particularly in sensitive environments under threat but where pollution levels are presently low. They may also have a beneficial effect on the health of their hosts by acting as heavy metal filters.
Trends in Ventilator-Associated Pneumonia Rates Within the German Nosocomial Infection Surveillance System (KISS)
Authors: Zuschneid I. , Schwab F. , Gastmeier P. , Geffers C. , Behnke M. , Rüden H. 
Published: February 2007

Objective.To investigate trends in ventilator-associated pneumonia (VAP) rates during participation in the German nosocomial infection surveillance system (Krankenhaus-Infektions-Surveillance-System [KISS]).Methods.A total of 71 ICUs that began participating in KISS in 1999 or later and continued participation for at least 36 months were selected. Beginning with the first month of participation, the pooled mean rate of VAP in the ICUs was calculated for each year of participation. The incidence densities for the 3 years of participation were compared using the Pearson x2 test. Relative risks (RRs) and 95% confidence intervals (CIs) were calculated. VAP rates were calculated for each ICU and year of participation, and rates for years 1 and 3 were compared using the Wilcoxon test for paired samples.Results.Twenty-nine medical-surgical, 18 medical, 20 surgical, 2 neurosurgical, and 2 pediatric ICUs met the selection criteria. Surveillance data were available on 181,275 patients, for whom there were 613,098 patient-days and 224,138 ventilator-days. A total of 2,043 cases of VAP were reported. The ICUs had a pooled VAP rate of 10.5 cases per 1,000 ventilator-days during year 1 of KISS surveillance. In year 2, the rate decreased by 19%, to 8.7 cases per 1,000 ventilator-days (RR, 0.81 [95% CI, 0.73-0.90]). In year 3, the rate decreased by 24% from year 1, to 8.0 cases per 1,000 ventilator-days (RR, 0.76; 95% CI, 0.68-0.85). Both results were significant (P < .001 by the Pearson x2 test). Comparison of the VAP rates of the ICUs did not show a significant difference between years 1 and 3 of KISS participation.Conclusion.Surveillance was associated with a significant reduction in the pooled rate of VAP during years 1-3 of KISS participation.