bluuebunny/crossref_metadata_2025 huggingface dataset:
Mortality in a Swedish rubber tire manufacturing plant: Occupational risks or an “unhealthy worker” effect?
Authors: Wingren Gun
Published: May 2006

Background

In this cohort study a classification of 12 work categories, with specified common exposures, is used to evaluate the mortality among workers in a Swedish rubber tire plant.

Methods

Mortality among the cohort members is compared with expected values from national rates. Standardized mortality ratios (SMR) were calculated for the total cohort, for sub‐cohorts and with the inclusion of a latency requirement.

Results

Male workers had increased risks for total mortality, circulatory death, respiratory death, mental disorders, epilepsy, injuries/poisoning, and for alcohol‐related death. Many risks were noted among workers exposed to dust, fumes, or vapor. No trend in risk with increasing duration of employment was seen.

Discussion

Some established risks for rubber workers could be related to some specified work categories. The highest risks were noted among workers having a very short duration of employment indicating a possible “unhealthy worker effect” associated with life‐style factors or to tasks offered to unskilled workers. Am. J. Ind. Med. 2006. © 2006 Wiley‐Liss, Inc.
Capturing cases in workers' compensation databases: The example of neck pain
Authors: Van Eerd Dwayne , Côté Pierre , Beaton Dorcas , Hogg‐Johnson Sheilah , Vidmar Marjan , Kristman Vicki
Published: May 2006

Background

There is a need to more accurately enumerate workers with musculoskeletal injuries who make lost‐time claims to workers compensation boards. The objective of this study is to develop an approach to more accurately enumerate these workers.

Methods

Lost‐time claims to the Ontario Workplace Safety & Insurance Board (WSIB) were reviewed. Using neck pain as an example, nature of injury and part of body codes were identified to classify cases. Claims of a random sample of 434 claimants were reviewed. The proportion of claimants classified as having neck pain was computed.

Results

The proportion of claimants classified with soft‐tissue injuries to the neck varied from 0.88 for codes including “neck/cervical region,” 0.69 for “back region” to 0.05 for those coded as “shoulder/upper arm.”

Conclusions

Restricting the enumeration of injuries to specific part of body codes can lead to a gross underestimation of the magnitude of soft‐tissue disorders in epidemiological studies using workers' compensation data. The proposed approach leads to more accurate enumeration. Am. J. Ind. Med. 49:557–568, 2006. © 2006 Wiley‐Liss, Inc.
Hydrocephaly, penoscrotal transposition, and digital anomalies associated with de novo pseudodicentric rearranged chromosome 13 characterized by classical cytogenetic methods and mBAND analysis
Authors: Christofolini Denise Maria , Yoshimoto Maisa , Squire Jeremy A. , Brunoni Décio , Melaragno Maria Isabel , Carvalheira Gianna
Published: May 2006

We report on a patient with hydrocephaly, penoscrotal transposition, oligodactyly, and minor anomalies. Comprehensive cytogenetic studies involving both classical cytogenetic methods and mBAND analysis were used to show a stable dicentric rearranged chromosome 13 that result in a 46,XY,psu dic(13;13)(13pter → 13q32::13q11 → 13pter) de novo karyotype. This aberration probably arose as a consequence of unequal sister chromatid breakage repair events. This report is the first to describe all of the most severe features associated with partial monosomy in one patient. Moreover, the delineation of monosomy 13q32 → qter in this patient facilitates identification of the developmental genes responsible for the clinical features within this region of chromosome 13. © 2006 Wiley‐Liss, Inc.
A newly recognized, likely autosomal recessive syndrome comprising agammaglobulinemia, microcephaly, craniosynostosis, severe dermatitis, and other features
Authors: Crow Yanick Joseph , Goodship J.A. , Wright C. , Coady A.M. , Conley M.E. , Gennery A.R.
Published: May 2006

We present a novel, likely autosomal recessive, multi‐system disorder seen in three siblings, two males and one female, born to nonconsanguineous parents. The disease manifests as agammaglobulinemia with marked microcephaly, significant developmental delay, craniosynostosis, a severe dermatitis, cleft palate, narrowing of the choanae, and blepharophimosis. The constellation of clinical signs seen in this family likely represents a new and recognizable form of agammaglobulinemia due to a defect in early B‐cell maturation. © 2006 Wiley‐Liss, Inc.
Autistic behavior in children with fragile X syndrome: Prevalence, stability, and the impact of FMRP
Authors: Hatton Deborah D. , Sideris John , Skinner Martie , Mankowski Jean , Bailey Donald B. , Roberts Jane , Mirrett Penny
Published: May 2006

We examined autistic behavior in a cross‐sectional sample of 179 children with fragile X syndrome (FXS) and a longitudinal subset of 116 children using the Childhood Autism Rating Scale (CARS) to (a) determine a prevalence of autistic behavior in FXS, (b) examine the stability of autistic ratings over time, and (c) assess the association between the fragile X mental retardation protein (FMRP) and autistic behavior. Approximately 21% of the sample of 129 children (25.9% of boys) scored at or above the cutoff for autism. CARS scores increased slowly, yet significantly, over time, and low levels of FMRP were associated with higher mean levels of autistic behavior as measured by the CARS. © 2006 Wiley‐Liss, Inc.
The FG syndrome: Report of a large Italian series
Authors: Battaglia A. , Chines C. , Carey J.C.
Published: May 2006

Initially described as a rare MCA/MR syndrome occurring only in boys, due to a recessive mutation on the X chromosome [Opitz and Kaveggia, 1974], the FG syndrome (FGS) now emerges as a more common disorder also occurring in girls. Based on over 50 reported cases, FGS is associated with developmental delay (especially speech), hypotonia, postnatal onset relative macrocephaly, prominent forehead, frontal hair upsweep, telecanthus, or ocular hypertelorism, thin vermilion border of the upper lip, relatively short fingers with broad thumbs and halluces, persistent fetal fingertip pads, anal anomalies, and/or constipation. Major malformations are rare, and include pyloric stenosis, anal agenesis, cryptorchidism, hypospadias, and congenital heart defects. Abnormal EEGs and seizures have been reported in almost 70% of patients. Brain MRI shows corpus callosum abnormalities associated with dilatation of lateral ventricles and, less frequently, periventricular nodular heterotopias, mild cerebellar defects, and reduced periventricular white matter. Chiari 1 malformation seems to be frequent. The behavior phenotype appears to be characterized by ADHD, and relatively less developed language, fine motor and executive function skills; whereas visual‐spatial abilities seem to be a relative strength. Five candidate loci are already known but no gene identified. We describe 25 patients referred to the Stella Maris Institute for evaluation of DD/MR, and diagnosed as FGS. They were between 2 and 15½ years at the first observation. High resolution banding, FRAXA/FRAXE DNA analysis, and subtelomere FISH analysis were performed in all of them, and all had normal results. Thirteen patients were followed‐up from 6 months to 9 years. Our report focuses on physical, neurological, developmental findings, and natural history of FGS. Experience with our series of patients suggests that the syndrome may be common, and should be routinely considered in the evaluation of children and adolescents with DD/MR. © 2006 Wiley‐Liss, Inc.
Synthesis, characterization, flocculation, and rheological characteristics of hydrolyzed and unhydrolyzed polyacrylamide‐grafted poly(vinyl alcohol)
Authors: Krishnamoorthi S. , Singh R. P.
Published: May 2006

Graft copolymers of poly(vinyl alcohol) and polyacrylamide (PVA‐g‐PAM) were synthesized using a ceric ion–induced solution polymerization technique at 28°C. Three grades of graft copolymers were synthesized with varying acrylamide concentrations. Three grades of hydrolyzed products of PVA‐g‐PAM were synthesized with varying concentrations of sodium hydroxide solution. Hydrolyzed and unhydrolyzed PVA‐g‐PAM were characterized by viscometry, X‐ray diffractometry, infrared spectroscopy, and thermal analysis. Rheological investigation was also carried out on the aqueous solutions of various samples. The flocculation characteristics of various materials were investigated by the use of jar and settling tests in 0.25 and 5 wt %, respectively, using kaolin and iron ore suspensions. Among the series of graft copolymers, the one with fewest but longest PAM chains showed superior performance. The flocculation characteristics of the best‐performing graft copolymer were compared with those of various commercially available flocculants in the two suspensions under investigation. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2109–2122, 2006
Divided loyalties: transdetermination and the genetics of tissue regeneration
Authors: Eissenberg Joel C.
Published: May 2006

Most tissues contain cells capable of the self‐renewal and differentiation necessary to maintain tissue and organ integrity. These somatic stem cells are generally thought to have limited developmental potential. The mechanisms that restrict cell fate decisions in somatic stem cells are only now being understood. This understanding will be important in the clinical exploitation of adult stem cells in tissue repair and replacement. Experiments performed over fifty years ago in Drosophila showed that developmental restriction could be relaxed in the proliferating larval cells that are destined to form the adult fly integument. This phenomenon, called transdetermination, can serve as a model for mechanisms of stem‐cell commitment. A recent publication1 sheds new light on the mechanism of transdetermination by demonstrating that loss of homeotic gene silencing leads to increased frequency of transdetermination. In addition, the authors link a specific signaling pathway induced by tissue regeneration to the relaxation of homeotic gene silencing. The data identify key mechanisms that control developmental homeostasis and cell fate restriction that could be manipulated to make somatic stem‐cell engineering possible. BioEssays 28: 574–577, 2006. © 2006 Wiley Periodicals, Inc.
Mitochondrial one‐carbon metabolism is adapted to the specific needs of yeast, plants and mammals
Authors: Christensen Karen E. , MacKenzie Robert E.
Published: May 2006

In eukaryotes, folate metabolism is compartmentalized between the cytoplasm and organelles. The folate pathways of mitochondria are adapted to serve the metabolism of the organism. In yeast, mitochondria support cytoplasmic purine synthesis through the generation of formate. This pathway is important but not essential for survival, consistent with the flexibility of yeast metabolism. In plants, the mitochondrial pathways support photorespiration by generating serine from glycine. This pathway is essential under photosynthetic conditions and the enzyme expression varies with photosynthetic activity. In mammals, the expression of the mitochondrial enzymes varies in tissues and during development. In embryos, mitochondria supply formate and glycine for purine synthesis, a process essential for survival; in adult tissues, flux through mitochondria can favor serine production. The differences in the folate pathways of mitochondria depending on species, tissues and developmental stages, profoundly alter the nature of their metabolic contribution. BioEssays 28: 595–605, 2006. © 2006 Wiley Periodicals, Inc.
Practical Use of Modified Maximum Likelihoods for Stratified Data
Authors: Bellio Ruggero , Sartori Nicola
Published: May 2006

Stratified data arise in several settings, such as longitudinal studies or multicenter clinical trials. Between‐strata heterogeneity is usually addressed by random effects models, but an alternative approach is given by fixed effects models, which treat the incidental nuisance parameters as fixed unknown quantities. This approach presents several advantages, like computational simplicity and robustness to confounding by strata. However, maximum likelihood estimates of the parameter of interest are typically affected by incidental parameter bias. A remedy to this is given by the elimination of stratum‐specific parameters by exact or approximate conditioning. The latter solution is afforded by the modified profile likelihood, which is the method applied in this paper. The aim is to demonstrate how the theory of modified profile likelihoods provides convenient solutions to various inferential problems in this setting. Specific procedures are available for different kinds of response variables, and they are useful both for inferential purposes and as a diagnostic method for validating random effects models. Some examples with real data illustrate these points. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Improved Exact Confidence Intervals for the Odds Ratio in Two Independent Binomial Samples
Authors: Lin Che‐Yang , Yang Ming‐Chung
Published: May 2006

For two independent binomial samples, the usual exact confidence interval for the odds ratio based on the conditional approach can be very conservative. Recently, Agresti and Min (2002) showed that the unconditional intervals are preferable to conditional intervals with small sample sizes. We use the unconditional approach to obtain a modified interval, which has shorter length, and its coverage probability is closer to and at least the nominal confidence coefficient. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The importance of locality in the visualization of large datasets
Authors: Brooke J. M. , Marsh J. , Pettifer S. , Sastry L. S.
Published: May 2006

Many scientific phenomena in large high‐resolution datasets such as the U.K. Ocean Circulation and Advanced Modelling (OCCAM) ocean model are better discovered through visualization than by algorithmic analysis: it is often more straightforward to see a feature than it is to characterize it numerically. Using traditional rendering techniques, the size of modern datasets presents a challenge for even high‐end graphical supercomputers, and the cost of such hardware limits its availability for day‐to‐day analysis. We present an architecture that brings visual analysis to the desktop by exploiting consumer‐grade graphics hardware in order to provide initial interactive exploration and Web services to enable finer‐grained analysis and interoperability with traditional visualization tools. Copyright © 2006 John Wiley & Sons, Ltd.
e‐Science and artificial neural networks in cancer management
Authors: Dolgobrodov S. D. , Marshall R. , Moore P. , Bittern R. , Steele R. J. C. , Cuschieri A.
Published: May 2006

We describe the origins of this project, its aims and its relevance to e‐Science research. Particle physicists at the University of Manchester with experience of artificial neural networks (ANNs) have collaborated with clinicians at the University of Dundee to produce an ANN that is intended to predict survival rates and to indicate management profiles for cancer patients. Comparisons are made between typical data handling problems in particle physics and health care. The problems associated with data procurement, namely reliability and censoring are described, together with a discussion of how these problems were addressed. The inputs to the ANN and its decision output are discussed. The reliability of the ANN is assessed quantitatively. The prototype secure Web‐based interface, which allows clinicians to input new patient data to the central node at the University of Manchester and to obtain prognoses from anywhere in the world is presented. For each topic, the e‐Science relevance is described and underlined. Copyright © 2006 John Wiley & Sons, Ltd.
Viruses and their uses in nanotechnology
Authors: Singh Pratik , Gonzalez Maria J. , Manchester Marianne
Published: May 2006

The use of materials derived from natural sources in materials science has allowed the harnessing of complex structures resulting from eons of evolutionary fine‐tuning. A better understanding of the structure and function of viruses has revealed a collection of natural molecular assemblies and containers with a variety of shapes, sizes, stabilities, dynamic properties, and chemical reactivities. Viruses are increasingly being used in materials science, engineering, and nanotechnology as tools and building blocks for electronics, chemistry, and biomedical science. Here we discuss different types of viruses presently in use, their physical properties, and their potential uses in a variety of nanotechnology applications. Drug Dev. Res. 67:23–41, 2006. © 2006 Wiley‐Liss, Inc.
Ultrasound‐mediated therapies using oil and perfluorocarbon‐filled nanodroplets
Authors: Dayton Paul A. , Matsunaga Terry O.
Published: May 2006

Over the past decade, nanotechnology has emerged as a research tool with applications in virtually all areas of science ranging from the computer industry to biotechnology. With respect to the latter, nanoparticles, or solid nanometer‐sized bodies, have been incorporated into biotechnology as drug‐delivery agents. We have developed a novel variant of the biotechnology, however, designing targeted, oil and perfluorocarbon‐filled, malleable nanodropets that are able to carry therapeutics selectively to areas of disease. In order to help facilitate delivery, we have combined this technology with ultrasound to aid and enhance the delivery of drug payloads via these nanodroplets, thereby increasing effective delivery of therapeutic and minimizing systemic toxicity effects. Drug Dev. Res. 67:42–46, 2006. © 2006 Wiley‐Liss, Inc.
Targeted nanoparticles for detecting and treating cancer
Authors: Sunderland Christopher J. , Steiert Matthias , Talmadge James E. , Derfus Austin M. , Barry Stephen E.
Published: May 2006

Enabled by their size and supramolecular structures, nanoparticles (that is, particles of approximately 10 to 100 nanometers) promise to be particularly capable agents in the detection, diagnosis, and treatment of cancer. When loaded with chemotherapeutic agents, nanoparticle delivery to cancerous tissues relative to healthy tissues may be favorably biased by size and through the attachment of targeting ligands to the surface of the particle. Nanoparticles may be made from a variety of materials, and in addition to chemotherapeutic payloads, nanoparticles can incorporate non‐bioactive elements useful as diagnostic and device agents. For example, the inclusion of iron oxide colloids enables nanoparticle use as magnetic resonance imaging (MRI) contrast agents, and also, through the application of an alternating magnetic field (AMF), enables the particle to generate enough heat to be used for hyperthermic therapeutic applications. In this report, we also introduce novel Magnetic Nanoparticle Hydro‐Gel (MagNaGelTM) materials comprised of chemotherapeutic agents, iron oxide colloids, and targeting ligands. MagNaGel particles were fabricated in the 20‐ to 40‐nm size range with very narrow size dispersion. These particles demonstrate high (>10 wt %) chemotherapeutic loading, tumor‐associated biomolecular binding, good magnetic susceptibility, and attractive toxicity and circulation profiles in mouse models. Looking forward, the convergence of drug and device on the nano‐scale promises treatment modalities that cannot be practiced through traditionally distinct drug and device combinations. MagNaGel nanoparticles are drug‐device hybrids that, when used in conjunction with diagnostic MRI and inductive heating, may play a key role in new and powerful cancer treatment regimens. Drug Dev. Res. 67:70–93, 2006. © 2006 Wiley‐Liss, Inc.
Proteolytic cleavage of versican during cardiac cushion morphogenesis
Authors: Kern Christine B. , Twal Waleed O. , Mjaatvedt Corey H. , Fairey Sarah E. , Toole Bryan P. , Iruela‐Arispe M. Luisa , Argraves W. Scott
Published: May 2006

The proteoglycan versican is essential to the formation of endocardial cushion mesenchyme by epithelial–mesenchymal transformation (EMT). A potentially important factor in the regulation of versican activity during cushion EMT is proteolysis by ADAMTS metalloproteinases. Using antibodies to the DPEAAE neoepitope created by ADAMTS proteolysis of versican, we detected the amino terminal 70‐kDa versican cleavage fragment in cardiac cushions. Initially (i.e., 9.5 days post coitum [dpc]), the fragment is associated with endocardial cells undergoing EMT and with newly derived mesenchymal cells. ADAMTS‐1 and its cofactor fibulin‐1 were also associated with these cells. As cushions become increasingly populated with mesenchymal cells (10.5–12.5 dpc), the fragment remains asymmetrically distributed compared with the pattern of total versican. Highest levels of the fragment are present in regions immediately subjacent to the endocardium characterized as having densely packed, rounded cells, lacking cellular protrusions. With further development (i.e., 12.5–14.5 dpc), the pattern of fragment distribution within cushions broadens to include the ECM surrounding loosely packed mesenchymal cells in the cushion core. Together, the findings reveal that versican proteolysis leading to the production of the 70‐kDa fragment is integral to the formation and differentiation of endocardial cushion mesenchyme. Developmental Dynamics 235:2238–2247, 2006. © 2006 Wiley‐Liss, Inc.
Novel Coordination Polymers Generated from Angular 2,2′‐Dipyridyl Ligands and Bis(hexafluoroacetylacetonate) Copper(II): Crystal Structures and Magnetic Properties
Authors: Delgado Salomé , Barrilero Aitor , Molina‐Ontoria Agustín , Medina Manuela E. , Pastor Cesar J. , Jiménez‐Aparicio Reyes , Priego José L.
Published: May 2006

The synthesis of the ligand 2,5‐bis(2‐pyridylethynyl)thiophene (L2) is described and the coordination chemistry of the 2,2′‐long conjugated bidentate ligands 1,2‐di(2‐pyridyl)butadiyne (L1), 2,5‐bis(2‐pyridylethynyl)thiophene (L2), and 2,2′‐dipyridyl disulfide (L3) with Cu(hfac)2 (hfac = hexafluoroacetylacetonate) is investigated. Three new coordination polymers {[Cu(hfac)2L]n (1 for L = L1, 2 for L = L2 and 3 for L = L3)} are prepared and fully characterized by infrared spectroscopy, elemental analysis, thermogravimetric analysis, and X‐ray diffraction. They are obtained by a combination of L1, L2, or L3 with Cu(hfac)2·H2O in dichloromethane (CH2Cl2) as the solvent. When CH2Cl2 solutions of 3 were left standing for longer than one day or were refluxed for two days, rearrangements took place and 3 was transformed into 4 and 5. Compounds 1–3 adopt a one‐dimensional chain structure with the copper atom in a six‐coordinate 4+2 pseudooctahedral geometry. In 1 and 2, four equatorial sites Cu–O/N and two axial sites Cu–O are found with an unusual cis orientation of two L1 or L2 ligands, respectively, while in 3 the four equatorial sites are defined by four oxygen atoms from two hfac chelating ligands and the axial sites by two nitrogen donors from two trans‐L3 ligands. Compound 4 contains a (1‐hydro‐2‐pyridinio)thio group that is bound to a hexafluoroacetylacetonate anion through a S–C bond and 5 is a molecular compound where the CuII ion is pentacoordinate to two oxygen atoms of the hfac anion, two nitrogen atoms of two 2‐pyridyl sulfide fragments, and one carbon atom of the CC(O)CF3 fragment, which has been inserted into the S–S bond of the 2,2′‐dipyridyl disulfide ligand, giving a new tridentate ligand. The reaction of L3 with copper acetate leads to the molecular 1:2 adduct Cu2(μ‐OAc)4(L3)2 (6), where the CuII ion is pentacoordinate to four oxygen atoms of four different acetate anions and one nitrogen atom from the pyridine ring of L3 to form a square‐pyramidal geometry. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Association of the A870G cyclin D1 gene polymorphism with genetic susceptibility to nasopharyngeal carcinoma
Authors: Catarino Raquel J. , Breda Eduardo , Coelho Vânia , Pinto Daniela , Sousa Hugo , Lopes Carlos , Medeiros Rui
Published: May 2006

Background.

Nasopharyngeal cancer (NPC) is multifactorial, and the genetic background may be a crucial etiologic factor. Cyclin D1 (CCND1) is a key regulator of the cell cycle, and its altered activity is associated with the development of cancer.

Methods.

We analyzed the A870G CCND1 polymorphism by polymerase chain reaction/restriction fragment length polymorphism (PCR‐RFLP) in 281 individuals, including 94 patients with NPC and 187 healthy individuals.

Results.

Our results indicate that individuals carrying two G alleles have a 2.17‐fold increase in the risk for the development of NPC (odds ratio [OR], 2.17; 95% confidence interval [CI], 1.19–3.98; p = .016). Age‐adjusted logistic regression analysis confirmed this association (adjusted odds ratio [aOR], 2.14; 95% CI, 1.14–4.04; p = .018). Multivariate analysis demonstrates an independent association between GG CCND1 genotype (aOR, 2.06), male sex (aOR, 2.66), and age at diagnosis (aOR, 2.02) regarding the development of undifferentiated NPC. The proportion of NPC cases attributable to the GG CCND1 genotype was 14.76%.

Conclusions.

Our results may be important in the definition of a biologic predictive profile for the development of NPC within our population. © 2006 Wiley Periodicals, Inc. Head Neck, 2006
Ratio control variate method for efficiently determining high‐dimensional model representations
Authors: Li Genyuan , Rabitz Herschel
Published: May 2006

The High‐Dimensional Model Representation (HDMR) technique is a family of approaches to efficiently interpolate high‐dimensional functions. RS(Random Sampling)‐HDMR is a practical form of HDMR based on randomly sampling the overall function, and utilizing orthonormal polynomial expansions to approximate the RS‐HDMR component functions. The determination of the expansion coefficients for the component functions employs Monte Carlo integration, which controls the accuracy of the RS‐HDMR interpolation. The control variate method is an established approach to improve the accuracy of Monte Carlo integration. However, this method is often not practical for an arbitrary functionf(x) because there is no general way to find the analytical control variate functionh(x), which needs to be very similar tof(x). In this article, we show that truncated RS‐HDMR expansions can be used ash(x) for arbitraryf(x), and a more stable iterative ratio control variate method was developed for the determination of the expansion coefficients for the RS‐HDMR component functions. As the asymptotic error (standard deviation) of the estimator given by the ratio control variate method is proportional to 1/N(sample size), it is more efficient than the direct Monte Carlo integration, whose error is proportional to$1/\sqrt{N}$. In an illustration of a four‐dimensional atmospheric model a few hundred random samples are sufficient to construct an RS‐HDMR expansion by the ratio control variate method with an accuracy comparable to that obtained by direct Monte Carlo integration with thousands of samples. © 2006 Wiley Periodicals, Inc. J Comput Chem 27: 1112–1118, 2006
Cover Picture: Macromol. Biosci. 5/2006
Authors: Shi Jun , Alves Natália M. , Mano João F.
Published: May 2006

Cover: Semi‐interpenetrated networks with calcium alginate and poly(N‐isopropylacrylamide) (PNIPAAM) were produced in order to prepare hydrogel beads with simultaneous pH and temperature responsive capability. The picture presents the release profile of indomethacin at pH 2.1 and 7.4 and at temperatures of 25 and 37°C. Further details can be found in the article by J. Shi, N. M. Alves, and J. F. Mano* on page 358.
Recent advances in antimalarial drug development
Authors: Vangapandu Suryanaryana , Jain Meenakshi , Kaur Kirandeep , Patil Premanand , Patel Sanjay R. , Jain Rahul
Published: May 2006

Malaria caused by protozoa of the genus Plasmodium, because of its prevalence, virulence, and drug resistance, is the most serious and widespread parasitic disease encountered by mankind. The inadequate armory of drugs in widespread use for the treatment of malaria, development of strains resistant to commonly used drugs such as chloroquine, and the lack of affordable new drugs are the limiting factors in the fight against malaria. These factors underscore the continuing need of research for new classes of antimalarial agents, and a re‐examination of the existing antimalarial drugs that may be effective against resistant strains. This review provides an in‐depth look at the most significant progress made during the past 10 years in antimalarial drug development. © 2006 Wiley Periodicals, Inc. Med Res Rev, 27, No. 1, 65–107, 2007
On the heat flux vector for flowing granular materials—part II: derivation and special cases
Authors: Massoudi Mehrdad
Published: May 2006

Heat transfer plays a major role in the processing of many particulate materials. The heat flux vector is commonly modelled by the Fourier's law of heat conduction and for complex materials such as non‐linear fluids, porous media, or granular materials, the coefficient of thermal conductivity is generalized by assuming that it would depend on a host of material and kinematical parameters such as temperature, shear rate, porosity or concentration, etc. In Part I, we will give a brief review of the basic equations of thermodynamics and heat transfer to indicate the importance of the modelling of the heat flux vector. We will also discuss the concept of effective thermal conductivity (ETC) in granular and porous media. In Part II, we propose and subsequently derive a properly frame‐invariant constitutive relationship for the heat flux vector for a (single phase) flowing granular medium. Standard methods in continuum mechanics such as representation theorems and homogenization techniques are used. It is shown that the heat flux vector in addition to being proportional to the temperature gradient (the Fourier's law), could also depend on the gradient of density (or volume fraction), and D (the symmetric part of the velocity gradient) in an appropriate manner. The emphasis in this paper is on the idea that for complex non‐linear materials it is the heat flux vector which should be studied; obtaining or proposing generalized form of the thermal conductivity is not always appropriate or sufficient. Copyright © 2006 John Wiley & Sons, Ltd.
Velocity‐selective arterial spin labeling
Authors: Wong Eric C. , Cronin Matthew , Wu Wen‐Chau , Inglis Ben , Frank Lawrence R. , Liu Thomas T.
Published: May 2006

In pathologies in which slow or collateral flow conditions may exist, conventional arterial spin labeling (ASL) methods that apply magnetic tags based on the location of arterial spins may not provide robust measures of cerebral blood flow (CBF), as the transit delay for the delivery of blood to target tissues may far exceed the relaxation time of the tag. Here we describe current methods for ASL with velocity‐selective (VS) tags (termed VSASL) that do not require spatial selectivity and can thus provide quantitative measures of CBF under slow and collateral flow conditions. The implementation of a robust multislice VSASL technique is described in detail, and data obtained with this technique are compared with those obtained with conventional pulsed ASL (PASL). The technical considerations described here include the design of VS pulses, background suppression, anisotropy with respect to velocity‐encoding directions, and CBF quantitation issues. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
Magnetic field correlation imaging
Authors: Jensen Jens H. , Chandra Ramesh , Ramani Anita , Lu Hanzhang , Johnson Glyn , Lee Sang‐Pil , Kaczynski Kyle , Helpern Joseph A.
Published: May 2006

A magnetic resonance imaging (MRI) method is presented for estimating the magnetic field correlation (MFC) associated with magnetic field inhomogeneities (MFIs) within biological tissues. The method utilizes asymmetric spin echoes and is based on a detailed theory for the effect of MFIs on nuclear magnetic resonance (NMR) signal decay. The validity of the method is supported with results from phantom experiments at 1.5 and 3 T, and human brain images obtained at 3 T are shown to demonstrate the method's feasibility. The preliminary results suggest that MFC imaging may be useful for the quantitative assessment of iron within the brain. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
Central fatigue in continuous and intermittent contractions of triceps brachii
Authors: Bilodeau Martin
Published: May 2006

Conflicting results have been found across studies concerning the effect of rest periods on the development of central fatigue during prolonged muscle activity. Thus, the aim of the present study was to assess differences in the development of central fatigue between continuous and intermittent elbow extension fatigue tasks in the same subjects. Force and electromyographic data were collected on eight healthy volunteers. The ability to maximally activate the triceps brachii muscle was assessed by delivering trains of electrical stimulation during maximal voluntary efforts. This was done before, during, and after three fatigue tasks involving a maximal contraction in elbow extension. One short‐duration (∼55‐s) and two long‐duration (3‐min) fatigue tasks were performed by all subjects on separate sessions. One 3‐min task was intermittent (5‐s rests every 30 s) and the other was continuous. The main findings were that the development and extent of central fatigue were task‐dependent, with a greater decrease in the ability to maximally activate triceps brachii observed for the 3‐min continuous task. Also, the voluntary activation (VA) ratio was found to be a more sensitive index of central fatigue than the central activation ratio (CAR). These results suggest that, when assessing central fatigue in patients, conclusions may vary depending on the continuous/intermittent nature of the task performed and the estimate of voluntary activation used. Muscle Nerve, 2006
Sural neuropathy: Etiologies and predisposing factors
Authors: Stickler D. E. , Morley K. N. , Massey E. W.
Published: May 2006

Isolated sural neuropathy is an uncommon diagnosis. We identified 36 patients with isolated sural neuropathy. Sixteen had various forms of ankle trauma, in three of whom the associated sural neuropathies developed following medical intervention. Three patients developed sural neuropathy associated with vasculitis, and there were single patients with schwannoma and ganglionic cyst. In patients without a history of trauma, structural causes, such as schwannoma or ganglionic cysts and vasculitis, should be considered and managed as appropriate. Muscle Nerve, 2006
Local feature analysis: A statistical theory for reproducible essential dynamics of large macromolecules
Authors: Zhang Zhiyong , Wriggers Willy
Published: May 2006

Multivariate statistical methods are widely used to extract functional collective motions from macromolecular molecular dynamics (MD) simulations. In principal component analysis (PCA), a covariance matrix of positional fluctuations is diagonalized to obtain orthogonal eigenvectors and corresponding eigenvalues. The first few eigenvectors usually correspond to collective modes that approximate the functional motions in the protein. However, PCA representations are globally coherent by definition and, for a large biomolecular system, do not converge on the time scales accessible to MD. Also, the forced orthogonalization of modes leads to complex dependencies that are not necessarily consistent with the symmetry of biological macromolecules and assemblies. Here, we describe for the first time the application of local feature analysis (LFA) to construct a topographic representation of functional dynamics in terms of local features. The LFA representations are low dimensional, and like PCA provide a reduced basis set for collective motions, but they are sparsely distributed and spatially localized. This yields a more reliable assignment of essential dynamics modes across different MD time windows. Also, the intrinsic dynamics of local domains is more extensively sampled than that of globally coherent PCA modes. Proteins 2006. © 2006 Wiley‐Liss, Inc.
Thrust force calculations for pressure safety valves
Authors: P.E. Robert D'Alessandro
Published: May 2006

When a pressure safety valve actuates, thrust forces are developed. These thrust forces must be considered for the proper installation of the relieving device. For gas or vapor compressible flow, Simpson developed thrust force plots that can be used to calculate the magnitude of the thrust force. Although these charts are available in the open literature, the assumptions behind the charts and the underlying equations are not. This article addresses these issues. All equations and fundamental assumptions are stated and all flow models are explained. Numerical examples are given to illustrate the use of the equations and the corresponding Simpson Charts. In addition, several important modifications to the original charts are noted. The thrust force equations for a relief valve operating with a subcritical nozzle and a subcritical outlet, which are absent from the original Simpson Charts, are included here. The extent of the region where the relief valve operates with a critical flow nozzle and a subcritical flow outlet is modified to account for backpressure effects. Finally, the concept of a minimum relief valve outlet to nozzle area ratio is introduced. © 2006 American Institute of Chemical Engineers Process Saf Prog, 2006
Light extraction process in moth‐eye structure
Authors: Kasugai H. , Nagamatsu K. , Miyake Y. , Honshio A. , Kawashima T. , Iida K. , Iwaya M. , Kamiyama S. , Amano H. , Akasaki I. , Kinoshita H. , Shiomi H.
Published: May 2006

We theoretically calculated the light extraction efficiency of the light‐emitting diodes (LEDs) with a moth‐eye structure by rigorous coupled wave analysis (RCWA). The dependences of light extraction efficiency on aspect ratio and period were measured. Light extraction efficiency was almost constant until the period of 170 nm and then gradually decreased with increasing of period. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Study of exciton hopping in AlGaN epilayers by photoluminescence spectroscopy and Monte Carlo simulation
Authors: Tamulaitis G. , Kazlauskas K. , Žukauskas A. , Mickevičius J. , Shur M. S. , Fareed R. S. Qhalid , Zhang J. P. , Gaska R.
Published: May 2006

Monte Carlo simulation of exciton hopping reveals the features of the potential profile in AlGaN (with Al content of ∼26%) responsible for S‐shaped and W‐shaped temperature dependences of photoluminescence band peak position and bandwidth, respectively. One of the samples was grown using the conventional metal‐organic chemical vapor deposition (MOCVD), while the second one was grown with the insertion of a buffer layer grown by migration enhanced MOCVD (MEMOCVDTM) technique. The potential profile is shown to be double‐scaled in both Al0.26Ga0.74N epilayers, and the exciton hopping occurs through random potential fluctuations within isolated low‐potential regions with the average energy of the localized states dispersed on the second scale. Both energy fluctuation scales were found to be in the range of 18‐20 meV and were independent of the growth technique used. Meanwhile, the carrier lifetime was 30 ps in the sample grown by conventional MOCVD and 190 ps in the sample grown using the MEMOCVDTM technique. We conclude that the difference in the lifetimes is caused by the density of nonradiative recombination centers rather than by the potential fluctuations affecting the carrier motion. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of V/III ratio on the optical properties of Eu‐doped GaN
Authors: Sawahata J. , Seo J. W. , Takiguchi M. , Saito D. , Nemoto S. , Akimoto K.
Published: May 2006

Effect of V/III ratio on the optical properties of Eu‐doped GaN grown by molecular beam epitaxy using NH3 as a nitrogen source was studied. The incorporation efficiency of Eu increased with decreasing NH3 flow rate. The intensity of the Eu‐related emission in samples grown under lower V/III ratio was seven times larger than those of higher V/III ratio. These results may be due to the increase of Eu concentration and of nitrogen vacancy complex which will play an important role in energy transfer from GaN to Eu. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Two to three dimensional transitions of InGaN and the impact of GaN overgrowth
Authors: Yamaguchi T. , Einfeldt S. , Gangopadhyay S. , Pretorius A. , Rosenauer A. , Falta J. , Hommel D.
Published: May 2006

The heteroepitaxial growth of InGaN on GaN was studied by in‐situ reflection high‐energy electron diffraction, atomic force microscopy, scanning tunneling microscopy and transmission electron microscopy. The misfit strain between InGaN and GaN was relaxed by the deposition of a few‐nm‐thick wetting layer and the subsequent formation of nano‐islands without misfit dislocations, which is the so‐called Stranski‐Krastanov growth mode. Thus, InGaN nano‐islands with a very high density of around 1012 cm–2 and a very small aspect ratio of ∼2.1 (diameter/height) were achieved. In this paper, we also discuss the problems regarding GaN overgrowth of an InGaN nano‐island layer. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Stimulated emission and carrier dynamics in AlInGaN multi‐quantum wells
Authors: Hashemizadeh S. A. , Wells J.‐P. R. , Brown J. , Murzyn P. , Jones B. D. , Wang T. , Parbrook P. J. , Fox A. M. , Mowbray D. J. , Skolnick M. S.
Published: May 2006

Pump‐probe measurements resonant with the lowest energy transition of 2 nm thick AlInGaN multiple quantum wells show fast decay components between 3 to 21 ps from stimulated emission. On a slower timescale contributions from spontaneous recombination of carriers are also observed. The inferred threshold for stimulated emission is near 50 µJ/cm2. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optimizing the internal quantum efficiency of GaInN SQW structures for green light emitters
Authors: Fuhrmann D. , Rossow U. , Netzel C. , Bremers H. , Ade G. , Hinze P. , Hangleiter A.
Published: May 2006

GaxIn1–xN/GaN single quantum well (QW) structures emitting in the range of 450 nm to 620 nm have been grown by MOVPE. Temperature and excitation power dependent photoluminescence (PL) was used to determine the internal quantum efficiency (IQE) for these structures. For the blue emitting QWs high IQE values on the order of 60% were achieved. Due to a reduced growth temperature, reduced growth rate and increased V/III ratio we obtained QWs with good morphology and high In content above 25%. Thinner QWs with high In content showed a clear improvement of IQE compared to QW‐structures with larger thickness but smaller In‐content emitting at the same wavelength. Between λ peak = 460 nm and 530 nm we observed a slight reduction in IQE with values of 58% at 490 nm and 40% at 525 nm. But towards λ peak = 620 nm IQE decreased due to the electric field induced separation of the electron and hole wavefunction down to 1%. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Low resistance and highly reflective ohmic contacts to p ‐type GaN using transparent interlayers for flip‐chip light emitting diodes
Authors: Song June‐O , Kwak J. S. , Hong Hyun‐Gi , Ferguson Ian T. , Seong Tae‐Yeon
Published: May 2006

Zn (3 nm)/Rh (100 nm) and oxidized Ag‐ITO (100 nm)/Al (200 nm) schemes for the formation of low resistance and highly reflective ohmic contacts for flip‐chip light emitting diodes were investigated. It is shown that annealing the samples at 430 and 530 °C for 1 min in air results in good ohmic behaviors with specific contact resistances of ∼10–5 Ωcm2 LEDs fabricated using the Zn/Rh contact layers give forward‐bias voltages of 3.09–3.12 V at the injection current of 20 mA. Furthermore, the oxidized Ag‐ITO film/Al contacts also show good ohmic characteristics with contact resistivity of 10–5 Ωcm2 when annealed at 330 °C for 5 min in vacuum. LEDs fabricated using the oxidized Ag‐ITO film/Al contacts layers give forward‐bias voltages of ∼3.40 V at 20 mA. It is clearly shown that a transparent contact interlayer is necessary to make high‐quality ohmic contacts to p ‐type GaN for thermally stable flip‐chip LEDs using Rh‐ and Al‐reflectors. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A novel furanocoumarin from Feroniella lucida exerts protective effect against lipid peroxidation
Authors: Phuwapraisirisan Preecha , Surapinit Serm , Tip‐pyang Santi
Published: May 2006

The protective effect of Feroniella lucida against lipid peroxidation was investigated. Bioassay‐guided separation using rat brain as a model led to the isolation of a new antioxidant furanocoumarin named feroniellamin (6) along with five known coumarins (1–5). The structure of 6 was characterized by interpretation of spectroscopic data. Feroniellamin inhibited lipid peroxidation with an IC50 value of 52 µm. Copyright © 2006 John Wiley & Sons, Ltd.
Factors that prevent learning in electrochemistry
Authors: Schmidt Hans‐Jürgen , Marohn Annette , Harrison Allan G.
Published: May 2006

Electrochemistry plays an important role in curricula, textbooks, and in everyday life. The purpose of the present study was to identify and understand secondary‐school students' problems in learning electrochemistry at an introductory chemistry level. The investigation covered four areas: (a) electrolytes, (b) transport of electric charges in electrolyte solutions, (c) the anode and the cathode, and (d) the minus and plus poles. Written tests were given to high‐school students in five cycles. The population from which random samples were drawn totalled 15,700 subjects. Students were asked to select the correct answers and to justify their choices. It was found that students based their reasoning on four alternative concepts: (a) During electrolysis, the electric current produces ions; (b) electrons migrate through the solution from one electrode to the other; (c) the cathode is always the minus pole, the anode the plus pole; and (d) the plus and minus poles carry charges. The results suggest a teaching strategy in which students first experience and learn about electrochemistry concepts. In the second step, appropriate concept terms are added, and students then are confronted with the alternative concepts described in this article. © 2006 Wiley Periodicals, Inc. J Res Sci Teach 44: 258–283, 2007
Intervention‐free Interval following Strictureplasty for Crohn’s Disease
Authors: Roy Pratik , Kumar Devinder
Published: May 2006

Introduction

Strictureplasty is now well established as a bowel‐sparing alternative for surgical treatment of complicated Crohn’s disease. Limited resection is still preferred in patients with uncomplicated disease, as subsequent reoperation rates are low.

Methods

A retrospective review of 26 patients who underwent surgery for small bowel Crohn’s disease between 1996 and 2004 was undertaken. A total of 96 small bowel strictureplasties had been performed; 19 patients had strictureplasties performed in isolation, and the remaining 7 patients underwent strictureplasty with concomitant limited resection.

Results

There was no operative mortality. The median follow‐up was 41 months. Four patients developed complications that required further surgery. At 41 months, 73.3% of patients undergoing strictureplasty alone and 79.7% undergoing strictureplasty with concomitant resection were intervention‐free. If followed up to 70 months or more, the same proportion of patients would remain intervention‐free. Four patients developed further recrudescent disease and required surgery: strictureplasty, limited resection, or both. Of these patients, 25% were intervention‐free at 41 months.

Conclusions

Our results show that strictureplasty alone or with concomitant resection can confer intervention‐free periods of 41 months or more in 73.3% of patients, suggesting that strictureplasty can be utilized as an alternative to limited resection in uncomplicated Crohn’s disease.