bluuebunny/crossref_metadata_2025_split huggingface dataset:
Practical Use of Modified Maximum Likelihoods for Stratified Data
Authors: Bellio Ruggero , Sartori Nicola 
Published: May 2006

AbstractStratified 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

AbstractFor 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

AbstractMany 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

AbstractWe 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

AbstractThe 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

AbstractOver 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

AbstractEnabled 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

AbstractThe 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

AbstractThe 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

AbstractBackground.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

AbstractThe 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
Recent advances in antimalarial drug development
Authors: Vangapandu Suryanaryana , Jain Meenakshi , Kaur Kirandeep , Patil Premanand , Patel Sanjay R. , Jain Rahul 
Published: May 2006

AbstractMalaria 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

AbstractHeat 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

AbstractIn 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

AbstractA 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

AbstractConflicting 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

AbstractIsolated 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

AbstractMultivariate 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.