bluuebunny/crossref_metadata_2025 huggingface dataset:
ℋ︁‐matrix preconditioners for symmetric saddle‐point systems from meshfree discretization
Authors: Le Borne Sabine , Oliveira Suely , Yang Fang
Published: April 2008

Meshfree methods are suitable for solving problems on irregular domains, avoiding the use of a mesh. To deal with the boundary conditions, we can use Lagrange multipliers and obtain a sparse, symmetric and indefinite system of saddle‐point type. Many methods have been developed to solve the indefinite system. Previously, we presented an algebraic method to construct an LU‐based preconditioner for the saddle‐point system obtained by meshfree methods, which combines the multilevel clustering method with the ℋ︁‐matrix arithmetic. The corresponding preconditioner has both ℋ︁‐matrix and sparse matrix subblocks. In this paper we refine the above method and propose a way to construct a pure ℋ︁‐matrix preconditioner. We compare the new method with the old method, JOR and smoothed algebraic multigrid methods. The numerical results show that the new preconditioner outperforms the preconditioners based on the other methods. Copyright © 2008 John Wiley & Sons, Ltd.
Numerical simulations of a transient injection flow at low Mach number regime
Authors: Beccantini A. , Studer E. , Gounand S. , Magnaud J.‐P. , Kloczko T. , Corre C. , Kudriakov S.
Published: April 2008

In this paper, a transient injection flow at low Mach number regime is investigated. Three different methods are used and analyzed. Two of them are based on asymptotic models of the Navier–Stokes equations valid for small Mach numbers, whereas the other is based on the full compressible Navier–Stokes equations, with particular care given to the discretization at low Mach numbers. Numerical solutions are computed both with or without the gravity force. Finally, the performance of the solvers in terms of CPU‐time consumption is investigated, and the sensitivity of the solution to some parameters, which affect CPU time is also performed. Copyright © 2008 John Wiley & Sons, Ltd.
Numerical solution to the unsteady two‐dimensional Schrödinger equation using meshless local boundary integral equation method
Authors: Dehghan Mehdi , Mirzaei Davoud
Published: April 2008

A meshless local boundary integral equation (LBIE) method is proposed to solve the unsteady two‐dimensional Schrödinger equation. The method is based on the LBIE with moving least‐squares (MLS) approximation. For the MLS approximation, nodal points spread over the analyzed domain are utilized to approximate the interior and boundary variables. A time‐stepping method is employed to deal with the time derivative. An efficient method for dealing with singular domain integrations that appear in the discretized equations is presented. Finally, numerical results are considered for some examples to demonstrate the accuracy, efficiency and high rate of convergence of this method. Copyright © 2008 John Wiley & Sons, Ltd.
Contact with friction in multi‐material arbitrary Lagrangian‐Eulerian formulations using X‐FEM
Authors: Vitali Efrem , Benson David J.
Published: April 2008

A contact method with friction for the multi‐dimensional Lagrangian step in multi‐material arbitrary Lagrangian–Eulerian (ALE) formulations is presented. In our previous research, the extended finite element method (X‐FEM) was used to create independent fields (i.e. velocity, strain rate, force, mass, etc.) for each material in the problem to model contact without friction. The research presented here includes the extension to friction and improvements to the accuracy and robustness of our previous study. The accelerations of the multi‐material nodes are obtained by coupling the material force and mass fields as a function of the prescribed contact; similarly, the velocities of the multi‐material nodes are recalculated using the conservation of momentum when the prescribed contact requires it. The coupling procedures impose the same nodal velocity on the coupled materials in the direction normal to their interface during the time step update. As a result, the overlap of materials is prevented and unwanted separation does not occur. Three different types of contacts are treated: perfectly bonded, frictionless slip, and slip with friction. Example impact problems are solved and the numerical solutions are presented. Copyright © 2008 John Wiley & Sons, Ltd.
Flammability and fire resistance of composites reinforced by natural fibers
Authors: Kozłowski Ryszard , Władyka‐Przybylak Maria
Published: April 2008

Natural fiber‐reinforced composites are more and more frequently applied to building industry and transportation. Therefore, the knowledge of their behavior during fire is of high importance. Flammability is one of very important parameters that often limits the application of composites to a given area. It is well‐known that addition of lignocellulosic fibers to polymer changes mechanical properties of the product obtained. However, little information is available on their fire performance. The purpose of this review was to obtain fire performance data for several types of composites reinforced by lignocellulosic fibers. Copyright © 2008 John Wiley & Sons, Ltd.
Sequence of cardiovascular changes in IUGR in pregnancies with and without preeclampsia
Authors: Mari Giancarlo , Hanif Farhan , Kruger Michael
Published: April 2008

Objective

The aim of this study was to determine the cardiovascular changes sequence in intrauterine‐growth‐restricted (IUGR) fetuses using Doppler ultrasound.

Methods

Sequential Doppler evaluations were carried out in 29 severe IUGR fetuses in pregnancies without maternal medical complications (group A) and in pregnancies complicated by preeclampsia (group B) delivered at ≤ 32 weeks. Nine fetal vessels and two cardiac valves were studied.

Results

One hundred and forty three Doppler studies were performed (median: five studies; range 3–9 per patient). There were 19 fetuses in the preeclamptic group and 10 fetuses in the second group. In group A IUGR fetuses, a progressive change was observed in the parameters studied more often than in group B IUGR fetuses (P < 0.05). In six cases, an abnormal tricuspid valve (TV) followed by an abnormal mitral valve (MV) Doppler was recorded prior to the occurrence of the intrauterine‐fetal demise.

Conclusions

Our data indicate that (1) in patients without preeclampsia a series of cardiovascular changes almost always occurs in severe IUGR fetuses; (2) the changes preceding intrauterine demise are right cardiac failure followed by left cardiac failure; (3) in patients with preeclampsia, the sequential Doppler changes are unpredictable and are seen in a few patients only. Copyright © 2008 John Wiley & Sons, Ltd.
Dansylated acrylic copolymer with potential for sensor applications: Synthesis and properties
Authors: Buruiana Emil C. , Zamfir Mirela , Buruiana Tinca
Published: April 2008

A novel copolymer has been prepared by free radical polymerization in dimethylformamide of 5‐dimethylamino‐1‐(β‐methacryloyloxyethylcarbamoyloxyethyl)‐N‐methylsulfonamido‐naphthalene (Dns‐Acr) and methyl methacrylate in 1:3 M ratio with azobis(isobutyronitrile) as the initiator. The structure, purity, and the chemical composition of the dansylated copolymer (Dns‐COPA) were confirmed by spectrophotometric (1HNMR, FTIR, UV/vis), thermal and analytical methods, GPC measurements, and AFM techniques. Compared with Dns‐Acr, whose fluorescence emission band appears at 510 and 430 nm (shoulder), the photoluminescence spectrum of the Dns‐COPA in DMF solution exhibited a strong fluorescence emission at 440 nm (I1), and a small shoulder at 520 nm (I2) accompanying the main signal. The emitting behavior of Dns‐COPA was investigated through a spectrofluorimetric titration experiment, the fluorescence measurements demonstrating that introduction of various acids into the solution has a significant effect upon the quenching of fluorescence. This ability of dansyl copolymer to suffer the protonation of the amino group in organic acidic phase may be exploited in sensor applications. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3774–3782, 2008
Photopolymerization with microscale resolution: Influence of the physico‐chemical and photonic parameters
Authors: Soppera Olivier , Jradi Safi , Lougnot Daniel J.
Published: April 2008

This article is aimed at demonstrating that physicochemical parameters can be used to control the spatial extent (length, width, and shape) of polymer objects in view of micro‐ and nano‐fabrication applications. In particular, we showed that oxygen quenching and internal filter effects could be turned to advantage to modulate the response of the material by controlling the threshold energy of polymerization and/or the shape of the light into the photopolymerizable medium. The experimental configuration used in this study is based on light‐induced polymerization at the extremity of an optical fiber that produces polymer micro‐objects after development. Spectroscopic approaches and polymerization threshold measurements were performed to quantitatively evaluate the influence of the physicochemical parameters on the micropatterning of photopolymerizable material. Interestingly, fluorescence that is usually regarded as a process competing with photopolymerization reaction, was used for controlling the fabrication process. By this means, it was possible to better understand the impact of a nonhomogeneous irradiation on photopolymerization process and thus, to tune the shape and the size of the final polymer objects. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3783–3794, 2008
Synthesis and characterization of a series of biodegradable and biocompatible PEG‐supported poly(lactic‐ran‐glycolic acid) amphiphilic barbell‐like copolymers
Authors: Lu De Dai , Yuan Jian Chao , Li Hongguang , Lei Zi‐Qiang
Published: April 2008

A series of multihydroxyl (2, 4, and 8) terminated poly(ethylene glycol)s and their biodegradable, biocompatible, and branched barbell‐like (PLGA)n‐b‐PEG‐b‐(PLGA)n (n = 1, 2, 4) copolymers have been synthesized. The lengths of the PLGA arms were varied by controlling the molar ratio of monomers to hydroxyl groups of PEG ([LA+GA]0/[OH]0 = 23, 45, 90). Chemical structures of synthesized barbell‐like copolymers were confirmed by both 1H and 13C‐NMR spectroscopies. Molecular weights were determined by 1H‐NMR end‐group analysis and gel permeation chromatography. The result of hydrolytic degradation indicated that the rate of degradation increased with the increase of arm numbers or with the decrease of arm lengths. The thermal properties were evaluated by using differential scanning calorimetry and a thermogravimetric analysis. The results indicated that the thermal properties of barbell‐like copolymers depended on the structural variations. The morphology of (PLGA)n‐PEG‐(PLGA)n copolymers self‐assembly films were investigated by atomic force microscope, the results indicated that the microphase separation existed in (PLGA)n‐PEG‐(PLGA)n copolymers. Because of the favorable biodegradability and biocompatibility of the PLGA and PEG, these results may therefore create new possibilities for these novel structural amphiphilic barbell‐like copolymers as potential biomaterials. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3802–3812, 2008
Benzophenothiazine and benzophenoxazine photosensitizers for triarylsulfonium salt cationic photoinitiators
Authors: Crivello James V.
Published: April 2008

An investigation of the photosensitization of triarylsulfonium salts at wavelengths greater than 400 nm was carried out with phenothiazine and phenoxazine compounds possessing extended benzenoid conjugation. Accordingly, three isomeric benzophenothiazines and 12H‐benzo[b]phenoxazine were prepared and employed for the photosensitization of several different types of triarylsulfonium salts. These compounds display a tail absorption that extends at least to 450 nm, making them useful for conducting photopolymerizations using long wavelength emission sources. The photosensitized vinyl and ring‐opening polymerizations of a number of monomers were conducted and the results are reported in this communication. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3820–3829, 2008
Statins: to switch or not to switch?
Authors: Goldsmith David , Duerden Martin
Published: April 2008

Two doctors argue for and against the policy of switching patients from expensive branded statins to lower‐cost generic formulations in order to reduce NHS prescribing costs. Copyright © 2008 Wiley Interface Ltd
Effects of Oral Administration of Stephania tetrandra S. Moore on Neovascularization of Retinal and Choroidal Capillaries of Diabetes in Rats
Authors: Tsutsumi Taiki , Hagino Nobuyoshi , Liang Xiao‐chun , Guo Sai‐shan , Kobayashi Shinjiro
Published: April 2008

In rats, an injection of streptozotocin (STZ) elevated blood levels of glucose 4 weeks later (STZ‐induced diabetes) and an over‐production of microvessels of retinal and choroidal capillaries of eyes developed. A previous study has shown that administration of Stephania tetrandra S. Moore (STSM) in culture prevented the over‐production of microvessels of those capillaries of STZ‐induced diabetes in vitro. Therefore, the study investigated whether or not orally administered STSM could inhibit over‐production of microvessels of those capillaries of STZ injected rats in vivo. When STSM was given at the same time as the STZ injection and continued daily for 7 weeks, STSM prevented the elevation of blood glucose level and over‐production of microvessels of those capillaries. When STSM was given after elevation of blood glucose level of glucose (4 weeks after STZ injection) and continued daily for 4 weeks, STSM lowered the elevated blood glucose level but had no effect on the over‐production of microvessels of those capillaries. It was inferred that deposition of Nϵ(carboxymethyl) lysine in retinal and choroidal tissues, which is induced by STZ‐induced diabetes may deteriorate the blood–retinal barrier and the blood–choroidal barrier. One might, therefore, speculate that advanced STZ‐induced diabetes may deteriorate the blood–retinal barrier and blood–choroidal barrier. Therefore, STSM may not reach the retinal and choroidal tissues in the posterior ocular region in vivo. Copyright © 2008 John Wiley & Sons, Ltd.
Antihyperglycemic and hypolipidemic effects of Costus speciosus in alloxan induced diabetic rats
Authors: Bavarva Jasmin H. , Narasimhacharya A. V. R. L.
Published: April 2008

Hyperglycemia, abnormal lipid and antioxidant profiles are the most usual complications in diabetes mellitus. In the present study, the antihyperglycemic, antihyperlipemic and antioxidant potency of an ethanol extract of Costus speciosus root was investigated in alloxan‐induced diabetic male (Charles Foster) rats. Four groups of alloxan diabetic rats (n = 6) were administered orally with different doses of Costus speciosus root extract (150, 300 and 450 mg/kg BW) and a standard drug, glibenclamide (600 µg/kg BW), for 4 weeks. Two groups of rats (n = 6) served as normal and diabetic controls. While the diabetic controls showed significant abnormal carbohydrate, lipid and antioxidant profiles, administration of 150 mg/kg BW dose neither improved glucose nor lipid metabolism and antioxidant levels. Administration of 300 and 450 mg/kg BW doses, however, resulted in a reversal of diabetes and its complications. Both doses significantly brought down blood glucose concentration (26.76%, 34.68%), increased glycogenesis and decreased glyconeogenesis bringing the glucose metabolism toward normalcy. These doses also reversed the hyperlipidemia by reducing plasma total lipid (12.87%, 178.24%), cholesterol (21.92%, 30.77%) and triglyceride (25.32%, 33.99%) and improved hepatic antioxidant enzyme activities. The high dose (450 mg/kg BW) was found to have more potential antioxidant activities compared with glibenclamide. It is concluded that Costus speciosus root extract possesses anti‐hyperglycemic, antihyperlipemic and antioxidative effects, which may prove to be of clinical importance in the management of diabetes and its complications. Copyright © 2008 John Wiley & Sons, Ltd.
Print uniformity of corrugated board in flexo printing: effects of corrugated board and halftone dot deformations
Authors: Holmvall Martin , Uesaka Tetsu
Published: April 2008

Print non‐uniformity is a major concern for flexo post‐printers. Many of these non‐uniformities are suspected to be caused by the corrugated board structure itself. Striping is the most obvious one, but also other print quality problems might be structure‐related. This work focuses on how deformations of the board might lead to print non‐uniformities, and if the deformation of halftone dots is the mechanism behind striping in halftone flexo post‐printing. Finite element models were used to analyse the effects of deformations of corrugated boards and compressed halftone dots in the printing nip. Distortions of the board due to non‐uniform hygro‐thermal strains were shown to be a potential cause of print non‐uniformities. Striping in halftone prints was found to be caused by differences in dot gain between areas above ridges and valleys of the flute structure. Copyright © 2008 John Wiley & Sons, Ltd.
Using δ15N and δ18O to evaluate the sources and pathways of NO in rainfall event discharge from drained agricultural grassland lysimeters at high temporal resolutions
Authors: Granger Steven J. , Heaton Tim H.E. , Bol Roland , Bilotta Gary S. , Butler Patricia , Haygarth Philip M. , Owens Philip N.
Published: April 2008

The origin of NO yielded in drainage from agricultural grasslands is of environmental significance and has three potential sources; (i) soil organic mater (SOM), (ii) recent agricultural amendments, and (iii) atmospheric inputs. The variation in δ15N‐NO and δ18O‐NO was measured from the ‘inter‐flow’ and ‘drain‐flow’ of two 1 ha drained lysimeter plots, one of which had received an application of 21 m3 of NH‐N‐rich agricultural slurry, during two rainfall events. Drainage started to occur 1 month after the application of slurry. The concentrations of NO‐N from the two lysimeters were comparable; an initial flush of NO‐N occurred at the onset of drainage from both lysimeters before levels quickly dropped to <1 mg NO‐N L−1. The isotopic signature of the δ15N‐NO and δ18O‐NO during the first two rainfall events showed a great deal of variation over short time‐periods from both lysimeters. Isotopic variation of δ15N‐NO during rainfall events ranged between −1.6 to +5.2‰ and +0.4 to +11.1‰ from the inter‐flow and drain‐flow, respectively. Variation in the δ18O‐NO ranged from +2.0 to +7.8‰ and from +3.3 to +8.4‰. No significant relationships between the δ15N‐NO or δ18O‐NO and flow rate were observed in most cases although δ18O‐NO values indicated a positive relationship and δ15N‐NO values a negative relationship with flow during event 2. Data from a bulked rainfall sample when compared with the theoretical δ18O‐NO for soil microbial NO indicated that the contribution of rainfall NO accounted for 8% of the NO in the lysimeter drainage at most. The calculated contribution of rainfall NO was not enough to account for the depletion in δ15N‐NO values observed during the duration of the rainfall event 2. The relationship between δ15N‐NO and δ18O‐NO from the drain‐flow indicated that denitrification was causing enrichment in the isotopes from this pathway. The presence of slurry seemed to cause a relative depletion in δ18O‐NO in the inter‐flow and δ15N‐NO in the drain‐flow compared with the zero‐slurry lysimeter. This may have been caused by increased microbial nitrification stimulated by the presence of increased NH‐N. Copyright © 2008 John Wiley & Sons, Ltd.
Direct adaptive control of a utility‐scale wind turbine for speed regulation
Authors: Frost Susan A. , Balas Mark J. , Wright Alan D.
Published: April 2008

The accurate modeling of wind turbines is an extremely challenging problem due to the tremendous complexity of the machines and the turbulent and unpredictable conditions in which they operate. Adaptive control techniques are well suited to nonlinear applications, such as wind turbines, which are difficult to accurately model and which have effects from poorly known operating environments. In this paper, we extended the direct model reference adaptive control (DMRAC) approach to track a reference point and to reject persistent disturbances. This approach was then used to design an adaptive collective pitch controller for a high‐fidelity simulation of a variable‐speed horizontal axis wind turbine. The objective of the adaptive pitch controller was to regulate generator speed in Region 3 and to reject step disturbances. The control objective was accomplished by collectively pitching the turbine blades.

The turbine simulation models the controls advanced research turbine (CART) of the National Renewable Energy Laboratory in Golden, Colorado. The CART is a utility‐scale wind turbine that has a well‐developed and extensively verified simulator. This novel application of adaptive control was compared in simulations with a classical proportional integrator (PI) collective pitch controller. In the simulations, the adaptive pitch controller showed improved speed regulation in Region 3 when compared with the PI pitch controller. Copyright © 2008 John Wiley & Sons, Ltd.
Testing whether genetic variation explains correlation of quantitative measures of gene expression, and application to genetic network analysis
Authors: Yu Zhaoxia , Wang Liewei , Hildebrandt Michelle A. T. , Schaid Daniel J.
Published: April 2008

Genetic networks for gene expression data are often built by graphical models, which in turn are built from pair‐wise correlations of gene expression levels. A key feature of building graphical models is the evaluation of conditional independence of two traits, given other traits. When conditional independence can be assumed, the traits that are conditioned on are considered to ‘explain’ the correlation of a pair of traits, allowing efficient building and interpretation of a network. Overlaying genetic polymorphisms, such as single nucleotide polymorphisms (SNPs), on quantitative measures of gene expression provides a much richer set of data to build a genetic network, because it is possible to evaluate whether sets of SNPs ‘explain’ the correlation of gene expression levels. However, there is strong evidence that gene expression levels are controlled by multiple interacting genes, suggesting that it will be difficult to reduce the partial correlation completely to zero. Ignoring the fact that some sets of SNPs can explain at least part of the correlation between gene expression levels, if not all, might result in missing important clues on the genetic control of gene expression. To enrich the assessment of the causes of correlation between gene expression levels, we develop methods to evaluate whether a set of covariates (e.g. SNPs, or even a set of quantitative expression transcripts) explains at least some of the correlation of gene expression levels. These methods can be used to assist the interpretation of regulation of gene expression and the construction of gene regulatory networks. Copyright © 2008 John Wiley & Sons, Ltd.
A joint back calculation model for the imputation of the date of HIV infection in a prevalent cohort
Authors: Taffé Patrick , May Margaret ,   the Swiss HIV Cohort Study
Published: April 2008

In studies of the natural history of HIV‐1 infection, the time scale of primary interest is the time since infection. Unfortunately, this time is very often unknown for HIV infection and using the follow‐up time instead of the time since infection is likely to provide biased results because of onset confounding. Laboratory markers such as the CD4 T‐cell count carry important information concerning disease progression and can be used to predict the unknown date of infection. Previous work on this topic has made use of only one CD4 measurement or based the imputation on incident patients only. However, because of considerable intrinsic variability in CD4 levels and because incident cases are different from prevalent cases, back calculation based on only one CD4 determination per person or on characteristics of the incident sub‐cohort may provide unreliable results. Therefore, we propose a methodology based on the repeated individual CD4 T‐cells marker measurements that use both incident and prevalent cases to impute the unknown date of infection. Our approach uses joint modelling of the time since infection, the CD4 time path and the drop‐out process. This methodology has been applied to estimate the CD4 slope and impute the unknown date of infection in HIV patients from the Swiss HIV Cohort Study. A procedure based on the comparison of different slope estimates is proposed to assess the goodness of fit of the imputation. Results of simulation studies indicated that the imputation procedure worked well, despite the intrinsic high volatility of the CD4 marker. Copyright © 2008 John Wiley & Sons, Ltd.
Comparative effect of melatonin and vitamin E on phenylhydrazine‐induced toxicity in the spleen of Funambulus pennanti
Authors: Sharma Shweta , Haldar Chandana
Published: April 2008

Phenylhydrazine (PHZ) oxidation resulting in free iron release followed by free radical generation has increased frequency of cancer. This study aims towards the dose‐dependent response of PHZ and the role of melatonin in comparison with vitamin E following PHZ‐induced toxicity within the lymphoid tissue (spleen) of Indian tropical seasonal breeder, Funambulus pennanti, during reproductively active phase. An increase in the damages in terms of lipid peroxidation (LPO), apoptosis percentage, and splenomegaly was observed following different doses of PHZ treatment, i.e., 0.025, 0.5, and 1 mg/100 g body weight (b.wt.), where dose of 1 mg/100 g b.wt. showed more significant damages. Both melatonin (0.5 mg/100 g b.wt.) and vitamin E (1 mg/100 g b.wt.) administration ameliorated oxidative damages of 1 mg/100 g b.wt. PHZ‐treated group. Melatonin altered PHZ‐induced responses significantly to a greater degree than vitamin E as evidenced by LPO status, SOD activity, and ABTS radical cation scavenging activity of antioxidants. Thus, melatonin might be able to restrict carcinogenic property of PHZ‐induced oxidative stress by protecting macromolecules of the cell from harmful effects of PHZ and instead preserving cell viability. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2009.
Investigating the fate of saxitoxins in biologically active water treatment plant filters
Authors: Kayal Nawal , Newcombe Gayle , Ho Lionel
Published: April 2008

The saxitoxins are potent neurotoxins, which can be produced by freshwater cyanobacteria. This study assessed the fate of five saxitoxins variants through biologically active laboratory filters containing media sourced from the filters beds of two water treatment plants (WTPs). Decreases in the concentration of the less toxic variants coincided with increases in the concentrations of the more toxic variants through the filters containing anthracite sourced from two different WTPs. No changes in toxin concentrations were evident through parallel filters containing sand. The results strongly suggest that organisms within the biofilm of the anthracite filters possessed the ability to biotransform the saxitoxins variants, which has important implications for drinking water treatment, particularly since this has the potential to increase the toxicity of the filtered water. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2008.
Genotoxicity of wastewaters used for irrigation of food crops
Authors: Ansari Mohd Ikram , Malik Abdul
Published: April 2008

In most towns of India, wastewater coming from both industrial and domestic sources and without any treatment is used to irrigate the agricultural crops. This practice has been polluting the soil, and pollutants could possibly reach the food chain. For the above reasons, the wastewaters of Ghaziabad City (India), which is used for irrigation, were sampled (at two different sites) and monitored for the presence of genotoxic agents from January 2005 to June 2007. Gas chromatographic analysis showed the presence of certain OC (DDE, DDT, Dieldrin, Aldrin, and Endosulfan) and OP (Dimethoate, Malathion, Methlyparathion, and Chlorpyrifos) pesticides in both the sampling sites. Wastewater samples were concentrated using XAD resins (XAD‐4 and XAD‐8) and liquid–liquid extraction procedures, and the extracts were assayed for genotoxic potential by Ames Salmonella/microsome test, DNA repair defective mutants, and bacteriophage λ systems. The test samples exhibited significant mutagenicity with TA98, TA97a, and TA100 strains with the probable role of contaminating pesticides in the wastewater. However, XAD‐concentrated samples were more mutagenic in both sites as compared to liquid–liquid‐extracted samples. The damage in the DNA repair defective mutants in the presence of XAD‐concentrated water samples were also found to be higher to that of liquid–liquid‐extracted water samples at the dose level of 20 μL/mL culture. All the mutants invariably exhibited significant decline in their colony‐forming units as compared to their isogenic wild‐type counterparts. The survival was decreased by 81.7 and 75.5% in polA− strain in site I, and 76.0 and 73.5% in site II in polA− under the same experimental conditions after 6 h of treatment with XAD‐concentrated and liquid–liquid‐extracted samples, respectively. A significant decrease in the survival of bacteriophage λ was also observed when treated with the test samples. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2009.
Hematotoxic and hepatotoxic effects of dichlorvos at sublethal dosages in rats
Authors: Celik Ismail , Yilmaz Zeycan , Turkoglu Vedat
Published: April 2008

The present study was designed to understand the effects of sublethal concentrations of dichlorvos (DIC) on hematological constituent [red blood corpuscles, white blood corpuscles (WBC), mean cell volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, platelet counts, hemoglobin and hematocrite levels] and serum damage marker enzymes (aspartate aminotransferase, alanin aminotransferase, alkaline phosphatase, and lactate dehydrogenase) in rats at subacute period under laboratory conditions. DIC at dosages of 5 and 10 ppm was administered orally to six male rats ad libitum during the tests for 4 weeks consecutively. According to the results, DIC treatments increased significantly the levels of serum marker enzyme activities, whereas they did not change hematologic constituent except for WBC number treated with both dosages of DIC. The observations presented led us to conclude that the administrations of subacute DIC induced the levels of damage marker enzymes and leukocytosis. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2009.
Growth retardation of fetal rats exposed to nicotinein utero: Possible involvement of CYP1A1, CYP2E1, and P‐glycoprotein
Authors: Wang Ting , Chen Man , Yan You‐e , Xiao Feng‐qin , Pan Xiao‐liang , Wang Hui
Published: April 2008

To elucidate the possible metabolic mechanism of intrauterine growth retardation induced by nicotine, this study determines the effects of prenatal nicotine exposure on fetal development and cytochrome P4501A1 (CYP1A1), CYP2E1, and P‐glycoprotein (Pgp) expression in maternal liver and placenta. Pregnant rats were given 1.0 mg/kg nicotine subcutaneously twice a day from gestational day (GD) 8 to GD 15, 18, or 21. In nicotine‐treated groups, fetal developmental parameters including body weight were significantly lower. The activities of CYP1A1 and CYP2E1 in maternal liver microsomes in nicotine‐treated groups increased significantly with progressing gestation when compared with the corresponding control, but returned to the level similar to the control in late pregnancy. Nicotine‐treated groups induced pathological changes and increased malondialdehyde (MDA) content in the placenta when compared with the control. The gene expressions ofCYP1A1andCYP2E1in the placenta increased significantly in nicotine‐treated groups on GD 15 and GD 18, but returned to the level similar to the corresponding control on GD 21. In nicotine group, there was a decrease ofmdr1aexpression on GD 15, GD 18, and GD 21, with the most significant decrease on GD 15. In contrast, no significant difference was found inmdr1bmRNA expression between the nicotine‐treated animals and the corresponding control. In comparison with the corresponding control, the placental Pgp protein significantly decreased on GD 15 and GD 18. Our results showed that prenatal nicotine exposure resulted in inhibition of fetal growth significantly. The induction of CYP2E1 and CYP1A1 gene expression by nicotine in the maternal liver and placenta may be involved with the observed increase in oxidative stress and lipid peroxidation. The inhibition of the placental Pgp expression by nicotine may also contribute to an increased susceptibility of the fetus to environmental toxins. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2009.
Effects of arsenate on microcystin content and leakage of Microcystis strain PCC7806 under various phosphate regimes
Authors: Gong Yan , Song Lirong , Wu Xingqiang , Xiao Bangding , Fang Tao , Liu Jiantong
Published: April 2008

Both arsenic pollution and eutrophication are prominent environmental issues when considering the problem of global water pollution. It is important to reveal the effects of arsenic species on cyanobacterial growth and toxin yields to assess ecological risk of arsenic pollution or at least understand naturally occurring blooms. The sensitivity of cyanobacteria to arsenate has often been linked to the structural similarities of arsenate and phosphate. Thus, we approached the effect of arsenate with concentrations from 10−8 to 10−4 M on Microcystis strain PCC7806 under various phosphate regimes. The present study showed that Microcystis strain PCC7806 was arsenate tolerant up to 10−4 M. And such tolerance was without reference to both content of intra‐ and extra‐cellular phosphate. It seems that arsenate involved the regulation of microcystin synthesis and cellular polyphosphate contributed to microcystin production of Microcystis responding to arsenate, since there was a positive linear correlation of the cellular microcystin quota with the exposure concentration of arsenate when the cells were not preconditioned to phosphate starvation. It is presumed that arsenate could help to actively export microcystins from living Microcystis cells when preconditioned to phosphate starvation and incubated with the medium containing 1 μM phosphate. This study firstly provided evidence that microcystin content and/or release of Microcystis might be impacted by arsenate if it exists in harmful algal blooms. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2009.
Property-directed incremental invariant generation
Authors: Bradley Aaron R. , Manna Zohar
Published: April 2008

A fundamental method of analyzing a system such as a program or a circuit is invariance analysis, in which one proves that an assertion holds on all reachable states. Typically, the proof is performed via induction; however, an assertion, while invariant, may not be inductive (provable via induction). Invariant generation procedures construct auxiliary inductive assertions for strengthening the assertion to be inductive. We describe a general method of generating invariants that is incremental and property-directed. Rather than generating one large auxiliary inductive assertion, our method generates many simple assertions, each of which is inductive relative to those generated before it. Incremental generation is amenable to parallelization. Our method is also property-directed in that it generates inductive assertions that are relevant for strengthening the given assertion. We describe two instances of our method: a procedure for generating clausal invariants of finite-state systems and a procedure for generating affine inequalities of numerical infinite-state systems. We provide evidence that our method scales to checking safety properties of some large finite-state systems.
Who Was William Ray Rumel?
Authors: Welling David R. , Rich Norman M. , Burris David G. , Boffard Kenneth D. , DeVries William C.
Published: April 2008

This report details the life and contributions of William Ray Rumel, an early cardiovascular surgeon known for his innovations, particularly the “Rumel tourniquet,” and the ability to repair the diseased mitral valve without replacing it.
Large solutions for the Laplacian with a power nonlinearity given by a variable exponent
Authors: Sabina de Lis José C. , García-Melián Jorge , Rossi Julio D.
Published: April 2008

In this paper we consider positive boundary blow-up solutions to the problem

\mathrm{\Delta }u = u^{q(x)}

in a smooth bounded domain

\Omega \subset \mathbb{R}^{n}

. The exponent

q(x)

is allowed to be a variable positive Hölder continuous function. The issues of existence, asymptotic behavior near the boundary and uniqueness of positive solutions are considered. Furthermore, since

q(x)

is also allowed to take values less than one, it is shown that the blow up of solutions on

∂Ω

is compatible with the occurrence of dead cores, i.e., nonempty interior regions where solutions vanish.
Effect of coffee drinking on platelets: inhibition of aggregation and phenols incorporation
Authors: Natella F. , Nardini M. , Belelli F. , Pignatelli P. , Di Santo S. , Ghiselli A. , Violi F. , Scaccini C.
Published: April 2008

Epidemiological studies indicate a J-shaped relationship linking coffee consumption and cardiovascular risk, suggesting that moderate coffee consumption can be beneficial. Platelet aggregation is of critical importance in thrombotic events, and platelets play a major role in the aetiology of several CVD. The aim of this study was to evaluate the effect of coffee drinking on platelet aggregationex vivo, using caffeine as control. A crossover study was performed on ten healthy subjects. In two different sessions, subjects drank 200 ml coffee, containing 180 mg caffeine, or a capsule of caffeine (180 mg) with 200 ml water. Platelets were separated from plasma at baseline and 30 and 60 min after coffee drinking. Platelet aggregation was induced with three different agonists: collagen, arachidonic acid and ADP. Coffee drinking inhibited collagen (P < 0·05 from baseline at time 30 min) and arachidonic acid (P < 0·05 from baseline at time 60 min) induced platelet aggregation. Caffeine intake did not affect platelet aggregation induced by the three agonists. Coffee consumption induced a significant increase of platelet phenolic acids (likely present as glucuronate and sulphate derivatives), caffeic acid, the principal phenolic acid in coffee, raising from 0·3 (sem0·1) to 2·4 (sem0·6) ng/mg (P < 0·01). Caffeine was not detectable in platelets. Coffee drinking decreases platelet aggregation, and induces a significant increase in phenolic acid platelet concentration. The antiplatelet effect of coffee is independent from caffeine and could be a result of the interaction of coffee phenolic acids with the intracellular signalling network leading to platelet aggregation.
Molecular analysis of predation on parasitized hosts
Authors: Traugott M. , Symondson W.O.C.
Published: April 2008

Predation on parasitized hosts can significantly affect natural enemy communities, and such intraguild predation may indirectly affect control of herbivore populations. However, the methodological challenges for studying these often complex trophic interactions are formidable. Here, we evaluate a DNA-based approach to track parasitism and predation on parasitized hosts in model herbivore-parasitoid-predator systems. Using singleplex polymerase chain reaction (SP-PCR) to target mtDNA of the parasitoid only, and multiplex PCR (MP-PCR) to additionally target host DNA as an internal amplification control, we found that detection of DNA from the parasitoid, Lysiphlebus testaceipes, in its aphid host, Aphis fabae, was possible as early as 5 min. post parasitism. Up to 24 h post parasitism SP-PCR proved to be more sensitive than MP-PCR in amplifying parasitoid DNA. In the carabid beetles Demetrias atricapillus and Erigone sp. spiders, fed with aphids containing five-day-old parasitoids, parasitoid and aphid DNA were equally detectable in both predator groups. However, when hosts containing two-day-old parasitoids were fed to the predators, detection of parasitoid prey was possible only at 0 h (immediately after consumption) and up to 8 h post consumption in carabids and spiders, respectively. Over longer periods of time, post-feeding prey detection success was significantly higher in spiders than in carabid beetles. MP-PCR, in which parasitoid and aphid DNA were simultaneously amplified, proved to be less sensitive at amplifying prey DNA than SP-PCR. In conclusion, our study demonstrates that PCR-based parasitoid and prey detection offers an exciting approach to further our understanding of host-parasitoid-predator interactions.
Does host plant influence parasitism and parasitoid species composition inLygus rugulipennis? A molecular approach
Authors: Gariepy T.D. , Kuhlmann U. , Gillott C. , Erlandson M.
Published: April 2008

LygusHahn plant bugs (Hemiptera: Miridae) are serious pests of a wide variety of economically important crops in North America. EuropeanPeristenus digoneutisLoan andP. relictusRuthe (Hymenoptera: Braconidae) are being considered for release in Canada as part of a classical biological control program forLygus. The attractiveness of different host plants to EuropeanPeristenushas not been addressed, but may be an important consideration prior to parasitoid release.Lygus rugulipennisPoppius nymphs were collected in the Northern Temperate Atlantic (NTA) ecoregion on red clover (Trifolium pratenseL.; Fabaceae) and chamomile (Matricaria recutitaL.; Asteraceae), and in the Western European Broadleaf Forest (WEBF) ecoregion on red clover and alfalfa (Medicago sativaL.; Fabaceae). Parasitism levels and parasitoid species were determined using a multiplex PCR assay forP. digoneutis,P. relictus, andP. pallipesCurtis. Mean parasitism levels inL. rugulipenniswere 45–49% in the NTA ecoregion and 25–32% in the WEBF ecoregion. However, in neither ecoregion were parasitism levels and parasitoid species compositions significantly different in nymphs from different host plant species. Furthermore, multiparasitism was low despite the fact thatP. digoneutisandP. relictusshare the same host species.
A molecular approach to identify prey of the southern rock lobster
Authors: Redd K.S. , Jarman S.N. , Frusher S.D. , Johnson C.R.
Published: April 2008

We demonstrate the use of molecular techniques to detect specific prey consumed by the southern rock lobster (Jasus edwardsii). A quick and non-lethal method was used to collect rock lobster faecal material and a molecular protocol was employed to isolate prey DNA from faecal samples. The isolated DNA was amplified using the polymerase chain reaction (PCR) with PCR primers designed to target specific prey items. Feeding experiments determined that DNA from black-lipped abalone (Haliotis rubra) and sea urchins (Centrostephanus rodgersiiandHeliocidaris erythrogramma) can be detected in rock lobster faecal samples within seven hours and remains present for up to 60 h after ingestion.
Pseudogenes and DNA-based diet analyses: a cautionary tale from a relatively well sampled predator-prey system
Authors: Dunshea G. , Barros N.B. , Wells R.S. , Gales N.J. , Hindell M.A. , Jarman S.N.
Published: April 2008

Mitochondrial ribosomal DNA is commonly used in DNA-based dietary analyses. In such studies, these sequences are generally assumed to be the only version present in DNA of the organism of interest. However, nuclear pseudogenes that display variable similarity to the mitochondrial versions are common in many taxa. The presence of nuclear pseudogenes that co-amplify with their mitochondrial paralogues can lead to several possible confounding interpretations when applied to estimating animal diet. Here, we investigate the occurrence of nuclear pseudogenes in fecal samples taken from bottlenose dolphins (Tursiops truncatus) that were assayed for prey DNA with a universal primer technique. We found pseudogenes in 13 of 15 samples and 1–5 pseudogene haplotypes per sample representing 5–100% of all amplicons produced. The proportion of amplicons that were pseudogenes and the diversity of prey DNA recovered per sample were highly variable and appear to be related to PCR cycling characteristics. This is a well-sampled system where we can reliably identify the putative pseudogenes and separate them from their mitochondrial paralogues using a number of recommended means. In many other cases, it would be virtually impossible to determine whether a putative prey sequence is actually a pseudogene derived from either the predator or prey DNA. The implications of this for DNA-based dietary studies, in general, are discussed.
Auditory neuropathy in a patient exposed to xylene: case report
Authors: Draper T H J , Bamiou D-E
Published: April 2008

Objective:

To report the case of an adult patient who developed auditory complaints following xylene exposure, and to review the literature on the effects of solvent exposure on hearing.

Case report:

The patient presented with a gradual deterioration in his ability to hear in difficult acoustic environments and also to hear complex sounds such as music, over a 40-year period. His symptoms began following exposure to the solvent xylene, and in the absence of any other risk factor. Our audiological investigations revealed normal otoacoustic emissions with absent auditory brainstem responses and absent acoustic reflexes in both ears, consistent with a diagnosis of bilateral auditory neuropathy. Central test results were also abnormal, indicating possible involvement of the central auditory pathway.

Conclusions:

To our knowledge, this is the first report of retrocochlear hearing loss following xylene exposure. The test results may provide some insight into the effect of xylene as an isolated agent on the human auditory pathway.
Effect of host populations on the intensity of ticks and the prevalence of tick-borne pathogens: how to interpret the results of deer exclosure experiments
Authors: PUGLIESE A. , ROSÀ R.
Published: April 2008

Deer are important blood hosts for feedingIxodes ricinusticks but they do not support transmission of many tick-borne pathogens, so acting as dead-end transmission hosts. Mathematical models show their role as tick amplifiers, but also suggest that they dilute pathogen transmission, thus reducing infection prevalence. Empirical evidence for this is conflicting: experimental plots with deer removal (i.e. deer exclosures) show that the effect depends on the size of the exclosure. Here we present simulations of dynamic models that take into account different tick stages, and several host species (e.g. rodents) that may move to and from deer exclosures; models were calibrated with respect toIxodes ricinusticks and tick-borne encephalitis (TBE) in Trentino (northern Italy). Results show that in small exclosures, the density of rodent-feeding ticks may be higher inside than outside, whereas in large exclosures, a reduction of such tick density may be reached. Similarly, TBE prevalence in rodents decreases in large exclosures and may be slightly higher in small exclosures than outside them. The density of infected questing nymphs inside small exclosures can be much higher, in our numerical example almost twice as large as that outside, leading to potential TBE infection risk hotspots.
Extraction of microsporidial DNA from modified trichrome-stained clinical slides and subsequent species identification using PCR sequencing
Authors: CHAN K. S. , KOH T. H.
Published: April 2008

Molecular techniques involving polymerase chain reaction (PCR) and sequencing provide a relatively simple and objective means of identifying microsporidia to species level. We modified previously described methods of DNA extraction and PCR conditions for identification of microsporidia from museum slides, clinical specimens and environmental samples and successfully identifiedVittaforma corneaein 11 out of 13 cases of microsporidial infection from used trichrome-stained slides of corneal scrapings from HIV-negative patients with keratoconjunctivitis.