bluuebunny/crossref_metadata_2025_split huggingface dataset:
Four Constructions of Highly Symmetric Tetravalent Graphs
Authors: Hill Aaron , Wilson Steve 
Published: August 2012

AbstractGiven a connected, dart‐transitive, cubic graph, constructions of its Hexagonal Capping and its Dart Graph are considered. In each case, the result is a tetravalent graph which inherits symmetry from the original graph and is a covering of the line graph.Similar constructions are then applied to a map (a cellular embedding of a graph in a surface) giving tetravalent coverings of the medial graph. For each construction, conditions on the graph or the map to make the constructed graph dart‐transitive, semisymmetric or ‐transitive are considered.
Hepatic transit time analysis using contrast enhanced MRI with Gd‐BOPTA: A prospective study comparing patients with liver metastases from colorectal cancer and healthy volunteers
Authors: Hohmann Joachim , Newerla Caroline , Müller Anja , Reinicke Christine , Skrok Jan , Frericks Bernd B. , Albrecht Thomas 
Published: August 2012

AbstractPurpose:To find out if the hepatic transit time (HTT) shortening, which was already proven in patients with liver metastases by other modalities, can also be detected with MRI.Materials and Methods:The Patient group consisted of 20 subjects with liver metastases from colorectal cancer and the control group of 21 healthy subjects. Baseline and post contrast images were acquired before and after administration of Gd‐BOPTA, using a T1‐weighted bolus test sequence. Arrival times (AT) of the contrast agent for the aorta, the hepatic artery, the portal vein and one hepatic vein were determined. Based on arrival time measurements HTT were calculated.Results:All analyses showed significantly shorter HTT in patients with metastases compared with healthy volunteers (P < 0.05). There were no false positives using a threshold of 10.4 s for arterial to venous HTT. For aortal to venous and portal to venous HTT a threshold of 12.5 s and 4 s was calculated, respectively. No significant correlation between HTT and involved liver segments, overall volume of metastases or subject age was found.Conclusion:We conclude that HTT measurements using contrast enhanced MRI with Gd‐BOPTA can detect hemodynamic changes due to metastatic liver disease from colorectal cancer. J. Magn. Reson. Imaging 2012; 36:1389–1394. © 2012 Wiley Periodicals, Inc.
ZnO Nanoparticle Induced Photo‐Kolbe Reaction, Fragment Stabilization and Effect on Photopolymerization Monitored by Raman–UV‐Vis Measurements
Authors: Schmitt Michael 
Published: August 2012

AbstractNano ZnO is able to photo‐initiate free‐radical polymerization of bulk acrylic esters. This kind of reaction is used in science and in industrial photocuring processes. Particle based initiators have the potential to solve the problem of migration. At the moment performance is not sufficient to utilize nanoparticle initiators for industrial applications. One way to improve the efficiency of the nanoparticles is to attach a modifier and to investigate the reactivity of the fragmentation products. Synthesis and reactivity improvement will be demonstrated using both computations and curing measurements made with a novel Raman–UV‐vis system. The combined system allows for real‐time in situ detection of the photopolymerization both in the transversal (deep‐) and in the lateral direction (area‐curing).
Exact subcategories of the category of locally convex spaces
Authors: Dierolf Bernhard , Sieg Dennis 
Published: August 2012

AbstractIn this paper we present a characterization whether the restriction \documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}$\mathcal {E}^{\prime }:=\lbrace (f,g)\in \mathcal {E}\,\,|\,\,f,g\in \mbox{Mor}({\mathcal {C}}^{\prime })\rbrace$\end{document} of the exact structure \documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}$\mathcal {E}$\end{document} of an exact category \documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}$({\mathcal {C}},\mathcal {E})$\end{document} in the sense of Quillen on a full additive subcategory \documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}${\mathcal {C}}^{\prime }$\end{document} of \documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}${\mathcal {C}}$\end{document} is again an exact structure. We apply our characterization to the exact structure \documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}$\mathcal {E}^{top}_{\mbox{LCS}}$\end{document} of short topologically exact sequences in the quasi‐abelian category \documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}$\mbox{LCS}$\end{document} of locally convex spaces and subcategories thereof.
Mass spectrometry‐based metabolomics towards understanding of gene functions with a diversity of biological contexts
Authors: Lv Haitao 
Published: August 2012

AbstractCurrently, mass spectrometry‐based metabolomics studies extend beyond conventional chemical categorization and metabolic phenotype analysis to understanding gene function in various biological contexts (e.g., mammalian, plant, and microbial). These novel utilities have led to many innovative discoveries in the following areas: disease pathogenesis, therapeutic pathway or target identification, the biochemistry of animal and plant physiological and pathological activities in response to diverse stimuli, and molecular signatures of host–pathogen interactions during microbial infection. In this review, we critically evaluate the representative applications of mass spectrometry‐based metabolomics to better understand gene function in diverse biological contexts, with special emphasis on working principles, study protocols, and possible future development of this technique. Collectively, this review raises awareness within the biomedical community of the scientific value and applicability of mass spectrometry‐based metabolomics strategies to better understand gene function, thus advancing this application's utility in a broad range of biological fields. © 2012 Wiley Periodicals, Inc., Mass Spec Rev 32:118–128, 2013
Finding hope in the midst of despair: My decade with Parkinson's disease and Lewy body dementia
Authors: Graboys Thomas B. 
Published: August 2012

AbstractLiving for 10 years with Parkinson's disease (PD) and Lewy body dementia (LBD) author Thomas B. Graboys, MD recounts the various losses — physical, emotional, social and intellectual — that ultimately add up to a loss of self inflicted by these progressive neurological diseases. No longer able to practice medicine, engage in athletics, or engage fully with his extended family, soon to include 11 grandchildren, Graboys nevertheless writes that there is one aspect of self PD and LBD cannot steal: the soul. © 2012 Movement Disorder Society
Notes on Metric Independent Analysis of Classical Fields
Authors: Segev Reuven 
Published: August 2012

A metric independent geometric framework for some fundamental objects of continuum mechanics is presented. In the geometric setting of general differentiable manifolds, balance principles for extensive properties are formulated and Cauchy's theorem for fluxes is proved. Fluxes in an n‐dimensional space are represented as differential (n − 1)‐forms. In an analogous formulation of stress theory, a distinction is made between the traction stress, enabling the evaluation of the traction on the boundaries of the various regions, and the variational stress, which acts on the derivative of a virtual velocity field to produce the virtual power density. The relation between the two stress fields is examined as well as the resulting differential balance law. As an application, metric‐invariant aspects of electromagnetic theory are presented within the framework of the foregoing flux and stress theory. Copyright © 2012 John Wiley & Sons, Ltd.
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Permittivity and performance of dielectric pads with sintered ceramic beads in MRI: early experiments and simulations at 3 T
Authors: Luo Wei , Lanagan Michael T. , Sica Christopher T. , Ryu YeunChul , Oh Sukhoon , Ketterman Matthew , Yang Qing X. , Collins Christopher M. 
Published: August 2012

AbstractPassive dielectric materials have been used to improve aspects of MRI by affecting the distribution of radiofrequency electromagnetic fields. Recently, interest in such materials has increased with the number of high‐field MRI sites. Here, we introduce a new material composed of sintered high‐permittivity ceramic beads in deuterated water. This arrangement maintains the ability to create flexible pads for conforming to individual subjects. The properties of the material are measured and the performance of the material is compared to previously used materials in both simulation and experiment at 3 T. Results show that both permittivity of the beads and effect on signal‐to‐noise ratio and required transmit power in MRI are greater than those of materials consisting of ceramic powder in water. Importantly, use of beads results in both higher permittivity and lower conductivity than use of powder. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.
SNR‐optimized phase‐sensitive dual‐acquisition turbo spin echo imaging: A fast alternative to FLAIR
Authors: Lee Hyunyeol , Park Jaeseok 
Published: August 2012

AbstractPhase‐sensitive dual‐acquisition single‐slab three‐dimensional turbo spin echo imaging was recently introduced, producing high‐resolution isotropic cerebrospinal fluid attenuated brain images without long inversion recovery preparation. Despite the advantages, the weighted‐averaging‐based technique suffers from noise amplification resulting from different levels of cerebrospinal fluid signal modulations over the two acquisitions. The purpose of this work is to develop a signal‐to‐noise ratio‐optimized version of the phase‐sensitive dual‐acquisition single‐slab three‐dimensional turbo spin echo. Variable refocusing flip angles in the first acquisition are calculated using a three‐step prescribed signal evolution while those in the second acquisition are calculated using a two‐step pseudo‐steady state signal transition with a high flip‐angle pseudo‐steady state at a later portion of the echo train, balancing the levels of cerebrospinal fluid signals in both the acquisitions. Low spatial frequency signals are sampled during the high flip‐angle pseudo‐steady state to further suppress noise. Numerical simulations of the Bloch equations were performed to evaluate signal evolutions of brain tissues along the echo train and optimize imaging parameters. In vivo studies demonstrate that compared with conventional phase‐sensitive dual‐acquisition single‐slab three‐dimensional turbo spin echo, the proposed optimization yields 74% increase in apparent signal‐to‐noise ratio for gray matter and 32% decrease in imaging time. The proposed method can be a potential alternative to conventional fluid‐attenuated imaging. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.
On‐coil multiple channel transmit system based on class‐D amplification and pre‐amplification with current amplitude feedback
Authors: Gudino Natalia , Heilman Jeremiah A. , Riffe Matthew J. , Heid Oliver , Vester Markus , Griswold Mark A. 
Published: August 2012

AbstractA complete high‐efficiency transmit amplifier unit designed to be implemented in on‐coil transmit arrays is presented. High power capability, low power dissipation, scalability, and cost minimization were some of the requirements imposed to the design. The system is composed of a current mode class‐D amplifier output stage and a voltage mode class‐D preamplification stage. The amplitude information of the radio frequency pulse was added through a customized step‐down DC‐DC converter with current amplitude feedback that connects to the current mode class‐D stage. Benchtop measurements and imaging experiments were carried out to analyze system performance. Direct control of B1 was possible and its load sensitivity was reduced to less than 10% variation from unloaded to full loaded condition. When using the amplifiers in an array configuration, isolation above 20 dB was achieved between neighboring coils by the amplifier decoupling method. High output current operation of the transmitter was proved on the benchtop through output power measurements and in a 1.5T scanner through flip angle quantification. Finally, single and multiple channel excitations with the new hardware were demonstrated by receiving signal with the body coil of the scanner. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.
Users' Experience of Physical Activity Monitoring Technology in Rheumatoid Arthritis
Authors: Tierney Marie , Fraser Alexander , Kennedy Norelee 
Published: August 2012

AbstractObjectivesThe aim of the present study was to qualitatively explore users' experiences of home monitoring of health with specific regard to physical activity monitors.MethodsFourteen participants were randomly selected from a larger sample of individuals with rheumatoid arthritis (RA) who had taken part in a physical activity monitoring study and had worn two physical activity monitors for seven days in their homes. These individuals were assigned to one of two focus groups. Each focus group lasted for between 40 minutes and an hour and was audio‐recorded. A semi‐structured questioning route was used, followed by subsequent theoretical thematic analysis.ResultsNo statistically significant differences were noted in the demographic factors between those who took part in the focus groups and the entire RA sample. Three distinct themes were identified: i) Experiences of having health monitored in the home, which was found to be largely positive; ii) Experiences of use of specific technology to monitor physical activity, which was generally reported as unobtrusive and not to impact significantly negatively on their daily life; iii) Perceptions and experiences of physical activity and exercise, which monitoring was reported to facilitate focusing on physical activity choices.ConclusionsThese focus groups were the first to highlight the perceptions held by individuals with RA regarding home monitoring and, in particular, physical activity monitoring. This has implications for those planning interventions for this group which involve home monitoring. Interesting findings were also highlighted regarding the perceptions and understanding of physical activity and exercise among people with RA. Copyright © 2012 John Wiley & Sons, Ltd.
On parallel solution of linear elasticity problems. Part III: higher order finite elements
Authors: Gustafsson Ivar , Lindskog Gunhild 
Published: August 2012

SUMMARYThis is the third part of a trilogy on parallel solution of the linear elasticity problem. We consider the separate displacement ordering for a plain isotropic problem with full Dirichlet boundary conditions. The parallel solution methods presented in the first two parts of the trilogy are here generalised to higher order by using hierarchical finite elements. We discuss node numberings on regular grids for high degree of parallelism and even processor load as well as the problem of stability of the modified incomplete Cholesky factorisations used. Several preconditioning techniques for the conjugate gradient method are studied and compared for quadratic finite elements. Bounds for the condition numbers of the corresponding preconditioning methods are derived, and computer experiments are performed in order to confirm the theory and give recommendations on the choice of method. The parallel implementation is performed by message passing interface. Copyright © 2012 John Wiley & Sons, Ltd.
UV Grafting of a Vinyl Monomer Onto a Methanol Plasma Polymer
Authors: Muir Benjamin W. , Tarasova Anna 
Published: August 2012

AbstractWe have shown that it is possible to graft a vinyl monomer from a plasma polymer surface in the presence of UV light without the use of a photoinitiator. A polyethylene glycol methacrylate (PEGMA) coating can be grown from the surface of a methanol plasma polymer via photopolymerization. It is proposed that the graft polymerization occurs from the generation and initiation of surface radicals by the applied UV light, in the methanol plasma polymer and the PEGMA monomer in solution. The coatings were characterised using X‐ray Photoelectron Spectroscopy and Atomic Force Microscopy (AFM). AFM analysis showed the interaction forces obtained between a silica probe and the PEGMA graft coatings to be repulsive and long‐ranged. The PEGMA coating was shown to be low fouling when placed in a protein solution. magnified image
Low temperature transport properties of the BiCuSeO system
Authors: Berardan David , Zhao Li‐Dong , Barreteau Celine , Dragoe Nita 
Published: August 2012

AbstractThe discovery of a 26 K superconductivity in the tetragonal iron‐based pnictide LaFeAsO1 − xFx (x = 0.05–0.12) has stimulated a tremendous search for superconductivity in a wide class of materials with similar structure. Beside superconductivity, promising thermoelectric properties have been discovered in this family in the cryogenic temperature range and in the p‐type BiCuSeO system around 400–600 °C. In this paper, we report on the effect of various substitutions on the low temperature properties of this system. Whatever the substitution, all samples revealed p‐type, and no superconductivity was observed. Moreover, although some of these compounds exhibit very promising thermoelectric properties above room temperature, this is not the case in the low temperature range.
A new structure for error covariance matrices and their adaptive estimation in EnKF assimilation
Authors: Wu Guocan , Zheng Xiaogu , Wang Liqun , Zhang Shupeng , Liang Xiao , Li Yong 
Published: August 2012

AbstractCorrect estimation of the forecast and observational error covariance matrices is crucial for the accuracy of a data assimilation algorithm. In this article we propose a new structure for the forecast error covariance matrix to account for limited ensemble size and model error. An adaptive procedure combined with a second‐order least squares method is applied to estimate the inflated forecast and adjusted observational error covariance matrices. The proposed estimation methods and new structure for the forecast error covariance matrix are tested on the well‐known Lorenz‐96 model, which is associated with spatially correlated observational systems. Our experiments show that the new structure for the forecast error covariance matrix and the adaptive estimation procedure lead to improvement of the assimilation results. Copyright © 2012 Royal Meteorological Society
Theoretical study of novel porphyrins bearing electron donor–acceptor groups
Authors: Caicedo Carolina , Martínez Ana , Rivera Ernesto 
Published: August 2012

AbstractThis research project is focused on molecules that comprise a series of asymmetrically A3B‐type meso‐substituted free‐base porphyrins and their related Zn‐metalloporphyrins. A and B were taken as electron‐donor and electron–acceptor groups. Full geometry optimizations without symmetry constrains were performed with B3LYP/6‐31G(d,P) methodology. Time‐dependent density functional theory calculations of the optimized structures indicate that there is a good agreement with the available experimental results. The highest occupied molecular orbital–lowest occupied molecular orbital (LUMO) gaps (ranging between 2.62 and 2.80 eV) are similar to those reported before for other porphyrins (2.29 eV). Also, the LUMO is situated close to the conduction band of titanium oxide, increasing the possibility of a charge transfer process. As porphyrins may act as electron transfer systems, the electron donor–acceptor capacity of these systems is characterized using two parameters; electrodonating (χ−) and electroaccepting (χ+) electronegativity. The main goal of this investigation is to analyze the electronic structure and the donor–acceptor properties of these porphyrins to see if these compounds could be useful for further applications related to the design of solar cells. © 2012 Wiley Periodicals, Inc.
Robust H ∞  control via a stable decentralized nonlinear output feedback controller
Authors: Harno Hendra G. , Petersen Ian R. 
Published: August 2012

SUMMARYThis paper presents a new method to construct a decentralized nonlinear robust H ∞  controller for a class of large‐scale nonlinear uncertain systems. The admissible uncertainties and nonlinearities in the system satisfy integral quadratic constraints and global Lipschitz conditions, respectively. The decentralized controller, which is required to be stable, is capable of exploiting known nonlinearities and interconnections between subsystems without treating them as uncertainties. Instead, additional uncertainties are introduced because of the discrepancies between nondecentralized and decentralized nonlinear output feedback controllers. The H ∞  control objective is to achieve an absolutely stable closed‐loop system with a specified disturbance attenuation level. A solution to this control problem involves stabilizing solutions to algebraic Riccati equations parametrized by scaling constants corresponding to the uncertainties and nonlinearities. This formulation is nonconvex; hence, an evolutionary optimization method is applied to solve the control problem considered. Copyright © 2012 John Wiley & Sons, Ltd.
Key exposure free chameleon hash schemes based on discrete logarithm problem
Authors: Lim Seongan , Lee Juhee , An Youngjoo 
Published: August 2012

ABSTRACTA chameleon hash scheme is a trapdoor collision‐resistant hash scheme, and it provides many interesting features in signature schemes with hash‐and‐sign construction. In this paper, we introduce the notion of key exposure threshold τ for a chameleon hash scheme for which a key exposure free chameleon hash scheme can be understood as the case with τ = ∞. We propose chameleon hash schemes CHτ with the key exposure threshold τ based on discrete logarithm problem (DLP). For τ < ∞, the proposed scheme is noninteractive and key exposure free as long as k ephemeral trapdoors are disclosed for k < τ. The proposed scheme CH∞ is a key exposure free chameleon hash scheme based on DLP, and it requires a label directory that can be managed by a third party. This improves the only known efficient key exposure free chameleon hash scheme based on DLP, which requires one interaction with the trapdoor holder. Copyright © 2012 John Wiley & Sons, Ltd.
Investigating Structural Alterations in Pyrogallol[4]arene‐Pyrene Nanotubular Frameworks
Authors: Kumari Harshita , Kline Steven R. , Wycoff Wei G. , Atwood Jerry L. 
Published: August 2012

AbstractSmall‐angle neutron scattering (SANS) and diffusion NMR studies are performed to investigate the stability and geometry of hydrogen‐bonded pyrene‐guest‐containing C‐hexylpyrogallol[4]arene (PgC6‐pyrene) nanotubular frameworks in solution. In the solid state, hydrogen‐bonded pyrogallol[4]arene tubes are formed; however, the scattering data for PgC6‐pyrene assemblies in acetone are best modeled as dimeric spheres of PgC6 with no pyrene guest. The result of diffusion NMR study also indicates the rearrangement of tubular entity into spherical framework in acetone. This is the first example of structural transformation of pyrogallol[4]arene nanotubes (guest‐exo) in solution. Individual hydrogen‐bonded spheres of PgC6 exhibits a uniform radius of ca. 8.6 Å and a diffusion coefficient of 9.12 × 10−10 m2 s−1 in acetone. The diffusion NMR measurements further gave, for the first time, insights into how the type of solvent (acetone vs. methanol vs. acetontitrile/D2O) governs the structural differences in these nanoassemblies. Solution‐phase structural alteration observed for PgC6‐pyrene gives evidence of enhanced stability of pyrogallol[4]arene nanocapsules over nanotubes.