bluuebunny/crossref_metadata_2025_split huggingface dataset:
Near‐contiguous spin echo imaging using matched‐phase RF and its application in velocity‐selective arterial spin labeling
Authors: Zun Zungho , Hargreaves Brian A. , Pauly John , Zaharchuk Greg 
Published: July 2013

PurposeThe minimum slice spacing in multislice imaging is limited by inter‐slice crosstalk due to an imperfect slice profile. This study sought to minimize the slice spacing using matched‐phase RF pulses and demonstrate its application in cerebral blood flow imaging using velocity‐selective arterial spin labeling.MethodsA spin‐echo matched‐phase 90°–180° RF pair was designed using Shinnar‐Le Roux algorithm in order to improve the slice profile of longitudinal magnetization, which plays a more critical role in creating interslice crosstalk than transverse magnetization. Both transverse and longitudinal slice profiles were compared between matched‐phase RF and sinc‐based RF pulses in simulations and measurements. Velocity‐selective arterial spin labeling was performed in normal volunteers using both RF pulses and standard deviation of cerebral blood flow time series was calculated to examine ASL signal stability.ResultsUsing designed matched‐phase RF, the longitudinal slice profile was sharpened without signal‐to‐noise ratio loss. In velocity‐selective arterial spin labeling imaging, the temporal standard deviation of cerebral blood flow measurements was reduced from 48 mL/100 g/min to 32 mL/100 g/min by 33% using matched‐phase RF pulses, and as a result, cerebral blood flow image quality improved.ConclusionThis study reports that near‐contiguous multislice imaging can be achieved using matched‐phase RF pulses without compromising signal‐to‐noise ratio and signal stability. Magn Reson Med 71:2043–2050, 2014. © 2013 Wiley Periodicals, Inc.
Model order reduction in hyperelasticity: a proper generalized decomposition approach
Authors: Niroomandi Siamak , Alfaro Icíar , González David , Cueto Elías , Chinesta Francisco 
Published: July 2013

SUMMARYThis paper deals with the extension of proper generalized decomposition methods to non‐linear problems, in particular, to hyperelasticity. Among the different approaches that can be considered for the linearization of the doubly weak form of the problem, we have implemented a new one that uses asymptotic numerical methods in conjunction with proper generalized decomposition to avoid complex consistent linearization schemes necessary in Newton strategies. This approach results in an approximation of the problem solution in the form of a series expansion. Each term of the series is expressed as a finite sum of separated functions. The advantage of this approach is the presence of only one tangent operator, identical for every term in the series. The resulting approach has proved to render very accurate results that can be stored in the form of a meta‐model in a very compact format. This opens the possibility to use these results in real‐time, reaching kHz feedback rates, or to be used in deployed, handheld devices such as smartphones and tablets. Copyright © 2013 John Wiley & Sons, Ltd.
Robust resilient H ∞  control for stochastic systems with Markovian jump parameters under partially known transition probabilities
Authors: Zong Guangdeng , Yang Dong 
Published: July 2013

SUMMARYIn this paper, the robust resilient H ∞  control problem for a class of stochastic systems with partially known transition probabilities is investigated. The system under consideration finds extensive applications because of the uncertainties involved in the system matrices and the general assumption upon the transition probabilities. Attention is focused upon the design of a robust resilient H ∞  state feedback controller, which guarantees the stochastic stability of the closed‐loop system and a prescribed H ∞  disturbance attenuation level for all admissible uncertainties. Sufficient criteria ensuring the stochastic stability and stabilization of the underlying systems are presented via LMIs formulation. A numerical example is provided to demonstrate the effectiveness of all the results. Copyright © 2013 John Wiley & Sons, Ltd.
‘If You Find Out Who Her Father is I Would Be Interested to Know’ TheKwermin in an EasternMin Context
Authors: Eggertsson Sveinn 
Published: July 2013

AbstractIn this paper the peripheral position of theKwermin in theMin regional context is discussed through a focus on two gift‐presentations, those of bridewealth and those presented to fully initiated men at the end of their initiatory process. The items of the traditional bridewealth gifts are discussed as well as the debate that emerged, after the discontinuation of this traditional presentation, whetherKwermin should take up the large bridewealth payments introduced from the highland Bimin or go back to an earlier custom of sister‐exchange (abu) between clans without great emphasis on bridewealth. However, it is suggested that the present day monetary claims, without their actual payment, may eventually serve to strengthen the previous practice ofabu. The gifts presented following full initiation are referred to asAfek's pubic hair and it is shown how these presentations can be understood as being Afek, or essential aspects of this highland's originating ancestor, creating novices as true men who are then presented toAfek in a way similar to the way wives are presented to husbands. It is suggested that such presentation of man to ancestress partly explains patriarchalKwermin men's reluctance to fully accept highland ideology, preferring to maintain their allegiance with the cultural hero of the lower mountains and the lowlands, Webnok.
A novel temperature‐step method to determine the glass transition temperature of ultrathin polymer films by liquid dewetting
Authors: Wang Jinhua , McKenna Gregory B. 
Published: July 2013

ABSTRACTA novel temperature‐step experimental method that extends the Bodiguel‐Fretigny liquid dewetting method of investigating polymer thin films is described and results presented from an investigation of thickness effects on the glass transition temperature (Tg) of ultrathin polystyrene (PS) films. Unlike most other methods of thin film investigation, this procedure promises a rapid screening tool to determine the overall profile of Tg versus film thickness for ultrathin polymer films using a limited number of samples. Similar to our prior observations and other literature data, with this new method obvious Tg depression was observed for PS thin films dewetting on both glycerol and an ionic liquid. The results for PS dewetting on the two different liquids are similar indicating only modest effects of the substrate on the Tg‐film thickness relationship. In both instances, the Tg depression is somewhat less than for similar PSs supported on silicon substrates reported in the literature. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013, 51, 1343–1349
Zincblende‐to‐wurtzite interface improvement by group III loading in Au‐seeded GaAs nanowires
Authors: Jacobsson Daniel , Lehmann Sebastian , Dick Kimberly A. 
Published: July 2013

Abstractmagnified imageAchieving control of the crystal structure is essential in III–V nanowires, since twin defects, stacking faults and uncontrolled zincblende–wurtzite polytypism could have detrimental effects on the physical properties. In addition, precise control of the crystal phases also opens up the possibility of homomaterial bandgap engineering. Here, we show by ex situ chemical analysis of the alloy seed particle that Ga‐rich conditions are required for growth of wurtzite GaAs nanowires using Au seed particles in MOVPE. Based on this understanding, we propose and demonstrate a growth procedure to significantly improve the crystal structure quality of the zincblende‐to‐wurtzite transition in GaAs nanowire heterostructures. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Mixed‐phase clouds in a turbulent environment. Part 1: Large‐eddy simulation experiments
Authors: Hill A. A. , Field P. R. , Furtado K. , Korolev A. , Shipway B. J. 
Published: July 2013

AbstractMixed‐phase clouds are thermodynamically unstable, i.e. with no other forcing ice will grow at the expense of supercooled liquid water, eventually leading to complete glaciation of the cloud. In the presence of dynamic forcing, e.g. regular motions or turbulent fluctuations, liquid water can be generated in an ice cloud. Earlier theoretical considerations have identified two necessary conditions that had to be satisfied to produce liquid water in a pre‐existing ice cloud: (i) the vertical velocity of an ice cloud parcel must exceed a threshold velocity and (ii) the vertical displacement of an ice cloud parcel must be above a threshold altitude to achieve water saturation. This article uses a large‐eddy simulation (LES) model to investigate whether satisfying these conditions alone can be used as a predictive tool for the occurrence of mixed‐phase clouds in a turbulent environment. It is shown that, in general for a range of microphysical assumptions, ice concentrations and thermodynamic conditions, identifying points that satisfy these two dynamic conditions results in a good estimate of the domain liquid cloud fraction and the evolution of the liquid cloud fraction over time from the LES. When relatively large liquid water contents are present, theory underpredicts liquid cloud fraction. Further, when ice is permitted to sediment, theory overpredicts liquid cloud fraction. Two modifications to the theory are suggested, and it is demonstrated how these reduce the deviation of predicted liquid cloud fraction from simulated cloud fraction.
Differential capacity and chronocoulometry studies of a quaternary ammonium surfactant adsorbed on Au(111)
Authors: Vivek J. P. , Monsur Abrar , Burgess Ian J. 
Published: July 2013

AbstractThe adsorption of a model quaternary ammonium surfactant, octyltrimethylammonium triflate, on Au(111) has been studied using capacity and chronoculometry methods. The surfactant adsorbs on the metal surface as a non‐dissociated ion pair at moderate potentials but can be desorbed by either positive or negative polarization. Within the adsorption region, two states are observed which correspond to a horizontal monolayer and a higher coverage vertically oriented film. Measurements of capacity transients upon potential steps reveal a slow organization of the molecular film. Although it is possible to equate the transients to known surfactant film aggregate geometries, the results are in disagreement with thermodynamic results. In comparison with other studies, the results indicate that the states of surfactant adsorption depend on surfactant chain length and electrode crystallography. Copyright © 2013 John Wiley & Sons, Ltd.
Ultrasensitive Telomerase Activity Detection by Telomeric Elongation Controlled Surface Enhanced Raman Scattering
Authors: Zong Shenfei , Wang Zhuyuan , Chen Hui , Cui Yiping 
Published: July 2013

AbstractTelomerase is now considered to be a valuable biomarker and therapeutic target in the diagnosis and treatment of cancerous diseases, which brings an urgent need in the development of fast and efficient telomerase detection strategies. Here, a new surface enhanced Raman scattering (SERS) based protocol using telomeric elongation controlled SERS (TEC‐SERS) effect for the ultrasensitive telomerase detection is presented. The TEC‐SERS protocol not only provides an unprecedented high sensitivity but also avoids laborious PCR procedures. The detection limit is ≈2–3 orders of magnitude lower than those of previously reported methods. This highly sensitive and straightforward TEC‐SERS protocol can be developed as a routine telomerase detection method, which would greatly facilitate the telomerase based ultra‐early diagnosis of malignant tumors and the fast screening of anti‐cancer drugs.
Stochastic unit commitment problem considering risk constraints and its improved GA‐based solution method
Authors: Xiong Gaofeng , Liu Xiping , Hashiyama Tomonori 
Published: July 2013

AbstractThis paper proposes a model of the stochastic unit commitment (SUC) problem, which takes account of the uncertainty of electric power demand and its resulting risk, and its solution method based on an improved genetic algorithm (IGA). The uncertainty of electric power demand is modeled using a set of scenarios which are introduced by scenario analysis. The variance, which measures the dispersion of generation costs of unit commitment schedule under each scenario around the expected generation cost, is used as a measure of risk. Based on the expected returns–variance of returns (E–V) rule in the theory of portfolio analysis, a utility function is devised by appending the variance of the expected generation cost into the original expected generation cost function, with consideration of the risk attitude of the generation companies and power exchange centers. The objective of this optimization problem is to minimize the utility function. The proposed IGA is used to solve this NP‐hard optimization problem. Based on numerical examples, the superiority of the IGA‐based solution method is verified through comparison with a traditional GA‐based solution method. Optimal schedules of SUC, as well as the expected costs and variances, are compared with/without risk constraints, and with different risk attitudes. Test results show that, in solving the SUC problem, it is necessary to consider the electric power demand uncertainty and its resulting risk, as well as the risk attitude of the decision maker. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
Endothelial cell motility, coordination and pattern formation during vasculogenesis
Authors: Czirok Andras 
Published: July 2013

How vascular networks assemble is a fundamental problem of developmental biology that also has medical importance. To explain the organizational principles behind vascular patterning, we must understand how can tissue level structures be controlled through cell behavior patterns like motility and adhesion that, in turn, are determined by biochemical signal transduction processes? We discuss the various ideas that have been proposed as mechanisms for vascular network assembly: cell motility guided by extracellular matrix alignment (contact guidance), chemotaxis guided by paracrine and autocrine morphogens, and multicellular sprouting guided by cell–cell contacts. All of these processes yield emergent patterns, thus endothelial cells can form an interconnected structure autonomously, without guidance from an external pre‐pattern. WIREs Syst Biol Med 2013, 5:587–602. doi: 10.1002/wsbm.1233This article is categorized under:

Models of Systems Properties and Processes > Cellular Models
Developmental Biology > Developmental Processes in Health and Disease
Models of Systems Properties and Processes > Organ, Tissue, and Physiological Models
Responses of the carbon and oxygen isotope compositions of desert plants to spatial variation in soil salinity in Central Asia
Authors: Matsuo Naoko , Ojika Kohei , Shuyskaya Elena , Radjabov Toshpulat , Toderich Kristina , Yamanaka Norikazu 
Published: July 2013

AbstractWe examined the isotopic parameters in two C3 species (Artemisia diffusa H. Krasch and Tamarix hispida Willd.) and a C4 species [Haloxylonaphyllum (Minkw.) Iljin.] growing or planted in soils with different levels of salinity in a Central Asian desert. The oxygen isotope ratios of stem water (δ18Ostem) in T. hispida and H. aphyllum distributed in high‐salinity zones were similar to the δ18O of artesian water (δ18Oartesian) and different from that in A. diffusa distributed in lower‐salinity zones. This indicates that T. hispida and H. aphyllum depend on water with low salinity in the deeper soil layer, whereas A. diffusa depends on water in the shallower soil layer that would be affected by salt accumulation. The carbon isotope composition of leaf organic matter (δ13Com) and oxygen isotope enrichment in leaf organic matter above stem water (Δ18Oom) were lower in A. diffusa than in the other species. The responses of δ13Com and Δ18Oom to soil salinity observed for T. hispida suggest that the species decreased its transpiration rate and increased its intrinsic water‐use efficiency in response to increasing soil salinity. The δ13Com and Δ18Oom of H. aphyllum were higher than those of the C3 species, and were not correlated with soil salinity, suggesting that H. aphyllum reduced its salt uptake by decreasing transpiration—even though it was able to access less saline water in the deeper soil layer. These results indicate that the water‐use strategy of desert plants in high‐salinity environments can be assessed based on their carbon and oxygen isotope ratios.
Synthesis, Surface Active Properties of Novel Gemini Surfactants with Amide Groups and Rigid Spacers
Authors: Hu Donghui , Guo Xiangfeng , Jia Lihua 
Published: July 2013

AbstractA series of novel cationic gemini surfactants, bis‐(N‐(3‐alkylamido‐propyl)‐N,N‐dimethyl)‐p‐phenylenediammonium dichloride, were synthesized. The structures of the gemini surfactants were characterized by IR, 1H NMR and 13C NMR. The Krafft temperatures of surfactants were determined through conductivity, the surface active properties in aqueous solution were studied at various temperatures by surface tension and conductivity. The thermodynamic functions of micellization process of the surfactants were also calculated by conductivity. The Krafft temperatures of the surfactants were 12, 13 and 28 °C. The values of CMC and Γmax decreased with increasing the length of hydrophobic chains, but the values of CMC and α increased with increasing temperature. The process of micellization is a spontaneous, exothermic and entropy‐driven process.
Gray matter atrophy pattern in elderly with subjective memory impairment
Authors: Peter Jessica , Scheef Lukas , Abdulkadir Ahmed , Boecker Henning , Heneka Michael , Wagner Michael , Koppara Alexander , Klöppel Stefan , Jessen Frank ,   Alzheimer's Disease Neuroimaging Initiative
Published: July 2013

AbstractBackgroundIndividuals with subjective memory impairment (SMI) report worsening of memory without impairment in cognitive tests. Despite normal cognitive performance, they may be at higher risk of cognitive decline compared with individuals without SMI.MethodsWe used a discriminative function (a support vector machine) trained on an independent data set of 226 healthy control subjects and 191 patients with probable Alzheimer's disease (AD) dementia to characterize the baseline gray matter patterns of 24 individuals with SMI and 53 control subjects. We tested for associations of these gray matter patterns with SMI presence, cognitive performance at baseline, and cognitive decline at follow‐up.ResultsIndividuals with SMI showed greater similarity to an AD gray matter pattern compared with control subjects without SMI. In addition, episodic memory decline was associated with an AD gray matter pattern in the SMI group.ConclusionsOur results indicate a link between the gray matter atrophy pattern of patients with AD and the presence of SMI. Furthermore, multivariate pattern recognition approaches seem to be a sensitive method for identifying subtle brain changes that correspond to future memory decline in SMI.
Three-dimensional exact coherent states in rotating channel flow
Authors: Wall D. P. , Nagata M. 
Published: July 2013

AbstractThree-dimensional exact, finite-amplitude solutions are presented for the problem of channel flow subject to a system rotation about a spanwise axis. The solutions are of travelling wave form, and may bifurcate as tertiary flows from the two-dimensional streamwise-independent secondary flow, or as secondary flows directly from the basic flow. For the tertiary flows, we consider solutions of spanwise superharmonic and subharmonic type. We distinguish flows on the basis of symmetry, originating eigenmode and major solution branch, and thus identify 15 distinct flows: 5 superharmonic tertiary, 5 subharmonic tertiary and 5 secondary flows. The tertiary flows all feature a single layer of vortical structures in the spanwise–wall-normal plane, the secondary flows feature single-, double-, triple- or quadruple-layer flow structures in this plane. All flows feature low-speed streamwise-orientated streaks in the streamwise velocity component and/or pulses of low-speed streamwise velocity. The streaks may be sinusoidal or varicose. Sinusoidal streaks are flanked by staggered streamwise vortices, varicose streaks and pulses are flanked by aligned vortices. A comparison with previous simulation and experimental studies finds that the simplest three-dimensional flows observed previously correspond to superharmonic tertiary flows bifurcating from the upper branch of the secondary flow. The mean absolute vorticity of the present flows is also considered. A flattening of the profile of this vorticity is observed in the central region of the channel for two-dimensional secondary and many of the three-dimensional flows, with two-step profiles also observed. This phenomenon is attributed to mixing of the vorticity across zones of the channel in which streamwise vortex structures exist, and is demonstrated by a two-dimensional model. The phenomenon appears to be distinct to that observed in fully turbulent rotating channel flows.
Logarithmic scaling of turbulence in smooth- and rough-wall pipe flow
Authors: Hultmark M. , Vallikivi M. , Bailey S. C. C. , Smits A. J. 
Published: July 2013

AbstractMeasurements of the streamwise component of the turbulent fluctuations in fully developed smooth and rough pipe flow are presented over an unprecedented Reynolds number range. For Reynolds numbers$R{e}_{\tau } \gt 20\hspace{0.167em} 000$, the streamwise Reynolds stress closely follows the scaling of the mean velocity profile, independent of the roughness, and over the same spatial extent. This observation extends the findings of a logarithmic law in the turbulence fluctuations as reported by Hultmark, Vallikivi & Smits (Phys. Rev. Lett., vol. 108, 2012) to include rough flows. The onset of the logarithmic region is found at a location where the wall distance is equal to ∼100 times the Kolmogorov length scale, which then marks sufficient scale separation for inertial scaling. Furthermore, in the logarithmic region the square root of the fourth-order moment also displays logarithmic behaviour, in accordance with the observation that the underlying probability density function is close to Gaussian in this region.