bluuebunny/crossref_metadata_2025_split huggingface dataset:
Improving peak local SAR prediction in parallel transmit using in situ S‐matrix measurements
Authors: Restivo Matthew , Raaijmakers Alexander , van den Berg Cornelis , Luijten Peter , Hoogduin Hans 
Published: May 2016

PurposePeak local specific absorption rate (pSAR10g) is an important parameter used to determine patient safety during radiofrequency transmission. pSAR10g predictions for parallel transmit MRI are affected by the level of coupling exhibited by a modeled array in the simulation environment. However, simulated array coupling is rarely equal to the physical array coupling. Accurately simulating the physical array coupling may improve the accuracy of predicted SAR levels.MethodsThe scattering parameter matrix (S‐matrix) of a prototype 4‐channel array was measured in situ using directional couplers installed on a 7T scanner. Agreement between the simulated and measured S‐matrix was achieved by using network co‐simulation with a modified cost function. B1+ maps acquired in a phantom were compared to B1+ distributions determined from simulations.ResultsThe modified co‐simulation technique forces the simulations to have S‐matrices similar to the measured values. A comparison of realistically versus ideally simulated coupling conditions shows that ideally simulated coupling can result in large ( > 40%) error in pSAR10g predictions, even when the array is reasonably tuned. The simulated B1+ distributions match the measured B1+ distributions better when the coupling is accurately simulated.ConclusionConsidering the measured array coupling matrix in numerical simulations eliminates a potential confound in pSAR10g prediction. Magn Reson Med 77:2040–2047, 2017. © 2016 International Society for Magnetic Resonance in Medicine
High quality three‐dimensional gagCEST imaging of in vivo human knee cartilage at 7 Tesla
Authors: Krishnamoorthy Guruprasad , Nanga Ravi Prakash Reddy , Bagga Puneet , Hariharan Hari , Reddy Ravinder 
Published: May 2016

PurposeTo develop a new faster and higher quality three‐dimensional (3D) gagCEST MRI technique for reliable quantification of glycosaminoglycan (GAG) present in the human knee cartilages.MethodsA new magnetization‐prepared 3D gradient echo‐based MRI pulse sequence has been designed to obtain the B0 inhomogeneity, B1 inhomogeneity, and CEST Z‐spectra images.ResultsThe gagCEST values of different compartments of knee cartilage are calculated using a newly developed technique for healthy subjects and a symptomatic knee cartilage degenerated subject. The effect of the acquired CEST saturation frequency offset step‐size was investigated to establish the optimal step‐size to obtain reproducible gagCEST maps. Our novel 3D gagCEST technique demonstrates markedly higher gagCEST contrast value than the previously reported 3D gagCEST studies. This study demonstrates the need for separate B0 and B1 inhomogeneity estimation and correction.ConclusionThe new technique provided high quality gagCEST maps with clearer visualization of different layers of knee cartilage with reproducible results. Magn Reson Med 77:1866–1873, 2017. © 2016 International Society for Magnetic Resonance in Medicine
Measuring the labeling efficiency of pseudocontinuous arterial spin labeling
Authors: Chen Zhensen , Zhang Xingxing , Yuan Chun , Zhao Xihai , van Osch Matthias J.P. 
Published: May 2016

PurposeOptimization and validation of a sequence for measuring the labeling efficiency of pseudocontinuous arterial spin labeling (pCASL) perfusion MRI.MethodsThe proposed sequence consists of a labeling module and a single slice Look‐Locker echo planar imaging readout. A model‐based algorithm was used to calculate labeling efficiency from the signal acquired from the main brain‐feeding arteries. Stability of the labeling efficiency measurement was evaluated with regard to the use of cardiac triggering, flow compensation and vein signal suppression. Accuracy of the measurement was assessed by comparing the measured labeling efficiency to mean brain pCASL signal intensity over a wide range of flip angles as applied in the pCASL labeling.ResultsSimulations show that the proposed algorithm can effectively calculate labeling efficiency when correcting for T1 relaxation of the blood spins. Use of cardiac triggering and vein signal suppression improved stability of the labeling efficiency measurement, while flow compensation resulted in little improvement. The measured labeling efficiency was found to be linearly (R = 0.973; P < 0.001) related to brain pCASL signal intensity over a wide range of pCASL flip angles.ConclusionThe optimized labeling efficiency sequence provides robust artery‐specific labeling efficiency measurement within a short acquisition time (∼30 s), thereby enabling improved accuracy of pCASL CBF quantification. Magn Reson Med 77:1841–1852, 2017. © 2016 International Society for Magnetic Resonance in Medicine Magn Reson Med 77:1841–1852, 2017. © 2016 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.
Integrated parallel reception, excitation, and shimming (iPRES) with multiple shim loops per radio‐frequency coil element for improved B0 shimming
Authors: Darnell Dean , Truong Trong‐Kha , Song Allen W. 
Published: May 2016

PurposeIntegrated parallel reception, excitation, and shimming (iPRES) coil arrays allow radio‐frequency currents and direct currents to flow in the same coils, which enables excitation/reception and localized B0 shimming with a single coil array. The purpose of this work was to improve their shimming performance by adding the capability to shim higher‐order local B0 inhomogeneities that are smaller than the radio‐frequency coil elements.MethodsA novel design was proposed in which each radio‐frequency/shim coil element is divided into multiple direct current loops, each using an independent direct current current, to increase the number of magnetic fields available for shimming while maintaining the signal‐to‐noise ratio of the coil. This new design is termed iPRES(N), where N represents the number of direct current loops per radio‐frequency coil element. Proof‐of‐concept phantom and human experiments were performed with an 8‐channel body coil array to demonstrate its advantages over the original iPRES(1) design.ResultsThe average B0 homogeneity in various organs before shimming and after shimming with the iPRES(1) or iPRES(3) coil arrays was 0.24, 0.11, and 0.05 ppm, respectively. iPRES(3) thus reduced the B0 inhomogeneity by 53% and further reduced distortions in echo‐planar images of the abdomen when compared with iPRES(1).ConclusioniPRES(N) can correct for localized B0 inhomogeneities more effectively than iPRES(1) with no signal‐to‐noise ratio loss, resulting in a significant improvement in image quality. Magn Reson Med 77:2077–2086, 2017. © 2016 International Society for Magnetic Resonance in Medicine
Resilient Coping Moderates the Effect of Trauma Exposure on Depression
Authors: Sinclair Vaughn G. , Wallston Kenneth A. , Strachan Eric 
Published: May 2016

AbstractPosttraumatic depression rates are increasing in the United States, and there is a great need to identify malleable factors that could moderate posttraumatic depression levels. The purpose of this study was to examine whether resilient coping moderates the effects of trauma exposure on depression, while controlling for neuroticism—an established predictor of depressive symptoms. This study used data from 3,734 pairs of twins from the community‐based University of Washington Twin Registry. Each twin pair was randomized with twin A in one subsample and twin B in the second subsample. The four‐item Brief Resilient Coping Scale measured resilient coping. The two‐item Patient Health Questionnaire measured depression. Multiple linear regression analyses were performed on each subsample, controlling for neuroticism. In addition to significant effects of neuroticism and trauma exposure on depression (p < .001), the effect of the interaction of resilient coping and trauma exposure on depression was significant in both subsamples (p < .01). High levels of resilient coping were associated with lower depression scores in the context of previous trauma exposure. Individuals high in resilient coping who experienced significant life traumas were less depressed after trauma exposure, even after controlling for neuroticism. Because coping skills may be learned, interventions that teach resilient coping to individuals with traumatic histories merit investigation. © 2016 Wiley Periodicals, Inc.
Handling Missing Data With Multilevel Structural Equation Modeling and Full Information Maximum Likelihood Techniques
Authors: Schminkey Donna L. , von Oertzen Timo , Bullock Linda 
Published: May 2016

AbstractWith increasing access to population‐based data and electronic health records for secondary analysis, missing data are common. In the social and behavioral sciences, missing data frequently are handled with multiple imputation methods or full information maximum likelihood (FIML) techniques, but healthcare researchers have not embraced these methodologies to the same extent and more often use either traditional imputation techniques or complete case analysis, which can compromise power and introduce unintended bias. This article is a review of options for handling missing data, concluding with a case study demonstrating the utility of multilevel structural equation modeling using full information maximum likelihood (MSEM with FIML) to handle large amounts of missing data. MSEM with FIML is a parsimonious and hypothesis‐driven strategy to cope with large amounts of missing data without compromising power or introducing bias. This technique is relevant for nurse researchers faced with ever‐increasing amounts of electronic data and decreasing research budgets. © 2016 Wiley Periodicals, Inc.
Beliefs About Dysmenorrhea and Their Relationship to Self‐Management
Authors: Chen Chen X. , Kwekkeboom Kristine L. , Ward Sandra E. 
Published: May 2016

AbstractDysmenorrhea is highly prevalent and is the leading cause of work and school absences among women of reproductive age. However, self‐management of dysmenorrhea is not well understood in the US, and little evidence is available on factors that influence dysmenorrhea self‐management. Guided by the Common Sense Model, we examined women's representations of dysmenorrhea (beliefs about causes, symptoms, consequences, timeline, controllability, coherence, and emotional responses), described their dysmenorrhea self‐management behaviors, and investigated the relationship between representations and self‐management behaviors. We conducted a cross‐sectional, web‐based survey of 762 adult women who had dysmenorrhea symptoms in the last six months. Participants had varied beliefs about the causes of their dysmenorrhea symptoms, which were perceived as a normal part of life. Dysmenorrhea symptoms were reported as moderately severe, with consequences that moderately affected daily life. Women believed they understood their symptoms moderately well and perceived them as moderately controllable but them to continue through menopause. Most women did not seek professional care but rather used a variety of pharmacologic and complementary health approaches. Care‐seeking and use of self‐management strategies were associated with common sense beliefs about dysmenorrhea cause, consequences, timeline, and controllability. The findings may inform development and testing of self‐management interventions that address dysmenorrhea representations and facilitate evidence‐based management. © 2016 Wiley Periodicals, Inc.
Comparison between Si/SiO2 mid‐gap interface states and deep levels associated with silicon‐oxygen superlattices in p‐type silicon
Authors: Simoen Eddy , Jayachandran S. , Delabie A. , Caymax M. , Heyns M. 
Published: May 2016

AbstractIn this paper, the deep levels found by deep‐level transient spectroscopy in Si‐O superlattices on p‐type silicon substrates are compared with the band of near mid‐gap hole traps typically observed at the Si/SiO2 interface. In addition, the impact of a post‐deposition Forming Gas Annealing is investigated. A large similarity between the two material systems is reported, which indicates that similar silicon‐oxygen bonds may be responsible for the deep hole traps.(© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A rapid method to assess a broad inventory of organic species in marine sediments using ultra‐high resolution mass spectrometry
Authors: Radović Jagoš R. , Silva Renzo C. , Snowdon Ryan W. , Brown Melisa , Larter Steve , Oldenburg Thomas B. P. 
Published: May 2016

RationaleA broad range of organic species in marine sediments is routinely used as biogeochemical proxies of Earth history. These species are typically analyzed using different analytical methods, targeting very specific components and often including time‐intensive sample preparation. There is, therefore, a need for a more comprehensive, rapid and high‐throughput approach to simultaneously analyze a broad range of known sedimentary polar species and also have a surveillance capability able to identify candidate new species classes.MethodsWhole solvent extracts from recently deposited Gulf of Mexico marine sediments were obtained after a simple, one‐step extraction. They were analyzed by Fourier transform ion cyclotron resonance mass spectrometry (FTICR‐MS), using atmospheric pressure photoionization in positive ion mode (APPI‐P), over a broad mass range (m/z 150–1500).ResultsFrom 3000 to over 5000 peaks per sample were assigned molecular formulae, and the majority of assignments (90%) showed an absolute error lower than 200 ppb. The detected species belong to the NO1–7, N4O2–8, O1–9, HC, N and OS compound classes, including known biomarker species such as pigments (e.g. tetrapyrrole macrocycles and carotenoids) and lipids (e.g. glycerol dialkyl glycerol tetraethers, GDGTs), but also compounds of still unknown detailed molecular structure, but with clear potential geochemical relevance.ConclusionsThe reported method enables rapid (12 min FTICR‐MS analysis time) and simultaneous detection of a broad range of multi‐heteroatom, polar organic species in whole sediment extracts. This allows for higher sample throughput, a more comprehensive investigation of sedimentary geochemistry, and potentially the discovery of new components and derivation of novel, multi‐species proxies. Copyright © 2016 John Wiley & Sons, Ltd.
Using Gaussian Mixture Model clustering for multi‐isotope analysis of archaeological fish bones for palaeobiodiversity studies
Authors: Göhring Andrea , Mauder Markus , Kröger Peer , Grupe Gisela 
Published: May 2016

RationaleModern methods in mass spectrometry permit fast accumulation of a huge amount of data. The analysis of multi‐isotope data sets of archaeological remains is of increasing importance for the study of palaeobiodiversity. However, common bivariate isotopic data analysis fails to detect certain patterns in a multi‐dimensional data set. This problem can be solved by cluster analysis.MethodsGaussian Mixture Model (GMM) clustering was applied to a multi‐isotope data set including 184 individual mass spectrometric measurements (δ13Ccollagen, δ15Ncollagen, δ13Ccarbonate, and δ18Ocarbonate values) of archaeological fish bones (n = 46) from the Viking Haithabu and medieval Schleswig sites in northern Germany. The number of components was first restricted to the expected number of three (freshwater, brackish, and marine environment). Subsequently, classification was conducted with respect to an optimal Bayesian Information Criterion (BIC).ResultsRestriction of the number of components to three clusters leads to the expected clustering results according to the gross ecological niches (freshwater, brackish, marine). The isotopic data of fish bone were, however, optimally clustered into four clearly separated, reasonable groups, namely a freshwater, a brackish, and two marine groups. The two marine clusters differ in their oxygen isotope ratios, indicating different water temperature and therefore probably imported fish. Restriction of the number of clusters resulted in better training and test results.ConclusionsThe GMM clustering method is applicable to complex multi‐dimensional stable isotope data sets established by isotope ratio mass spectrometry (IRMS). This exemplary application resulted in an identification of habitat preferences and non‐local individuals. Depending on the scientific question to be solved, restriction of the cluster size could lead to a better reproducibility; however, with loss of dissolution. Copyright © 2016 John Wiley & Sons, Ltd.
Architecting cloud‐enabled systems: a systematic survey of challenges and solutions
Authors: Chauhan Muhammad Aufeef , Babar Muhammad Ali , Benatallah Boualem 
Published: May 2016

SummaryThe literature on the challenges of and potential solutions to architecting cloud‐based systems is rapidly growing but is scattered. It is important to systematically analyze and synthesize the existing research on architecting cloud‐based software systems in order to build a cohesive body of knowledge of the reported challenges and solutions. We have systematically identified and reviewed 133 papers that report architecture‐related challenges and solutions for cloud‐based software systems. This paper reports the methodological details, findings, and implications of a systematic review that has enabled us to identify 44 unique categories of challenges and associated solutions for architecting cloud‐based software systems. We assert that the identified challenges and solutions classified into the categories form a body of knowledge that can be leveraged for designing or evaluating software architectures for cloud‐based systems. Our key conclusions are that a large number of primary studies focus on middleware services aimed at achieving scalability, performance, response time, and efficient resource optimization. Architecting cloud‐based systems presents unique challenges as the systems to be designed range from pervasive embedded systems and enterprise applications to smart devices with Internet of Things. We also conclude that there is a huge potential of research on architecting cloud‐based systems in areas related to green computing, energy efficient systems, mobile cloud computing, and Internet of Things. Copyright © 2016 John Wiley & Sons, Ltd.
Crystal Structure and Hydrate Water Content of Synthetic Hellyerite, NiCO3·5.5H2O
Authors: Bette Sebastian , Rincke Christine , Dinnebier Robert E. , Voigt Wolfgang 
Published: May 2016

AbstractA sample of pure, artificial hellyerite was synthesized in aqueous solution at 0 °C. The recorded X‐ray diffraction pattern completely agrees with the reference data given for natural hellyerite. Laboratory high resolution X‐ray powder diffraction, applying global optimization methods and Rietveld refinement, was employed to solve the crystal structure. Synthetic hellyerite was determined to crystallize in the primitive monoclinic space group P2/m (no. 10) with a = 10.769(2) Å, b = 7.295(2) Å, c = 9.343(2) Å, and β = 94.042(2)°. The crystal structure consists of edge‐linked, isolated pairs of Ni2(CO3)2(H2O)8 octahedra and non‐coordinating water molecules. According to structure solution and thermal analysis the molecular formula of hellyerite was corrected from NiCO3·6H2O to NiCO3·5.5H2O. The title compound was characterized by scanning electron microscopy, IR‐, Raman‐, and UV/Vis spectroscopy.
Ventilation in Trauma Patients: The First 24 h is Different!
Authors: Hardcastle Timothy Craig , Muckart David J. J. , Maier Ronald V. 
Published: May 2016

AbstractIntroductionVentilation of major trauma patients is often needed in both the acute (emergency department and early ICU phase) and subsequent phases of trauma care for those who need ICU admission. What is unclear is whether ICU ventilation strategies should be directly extrapolated to the acute phase of treatment.MethodsThis paper reviews the ARDS.net study, highlights recent developments in ventilation strategies, and provides practical ventilation guidance to the trauma surgeon for acute phase (in the ED or ICU) and the subsequent phase of ICU care.ResultsThe acute phase of care in the ED and the ICU is different from the subsequent phases of ICU care as the lung is more recruitable and there are other aspects of resuscitation from metabolic acidosis and traumatic brain injury, which require a different ventilation strategy to the traditional ARDS.net approach.Discussion and conclusionThe acute phase is different from the subsequent phase of care and there appears to be some inappropriate extrapolation of ICU practice to the acute phase. Application of the proposed ventilation strategies should ensure an optimal outcome. It is important to treat patients as individuals during assessment and treatment.
Micellar Growth in Cetylpyridinium Chloride/Alcohol System: Role of Long Chain Alcohol, Electrolyte and Surfactant Head Group
Authors: Karayil Jasila , Kumar Sanjeev , Talmon Yeshayahu , Hassan P. A. , Tata B. V. R. , Sreejith Lisa 
Published: May 2016

AbstractThe microstructural transition of aqueous 0.1 M cetylpyridinium chloride (CPC) in the combined presence of salt KBr and long chain alcohol (C9OH‐C12OH) has been studied as a function of alcohol concentration, electrolyte concentration and temperature. The viscosity of the CPC/KBr micellar system showed a peaked behavior with alcohol concentration (C0), due to alcohol induced structural transition, which was confirmed by dynamic light scattering (DLS) and rheological analysis. Besides C0, the chain length of alcohol (n) was found to show a remarkable effect on the micellization behavior of CPC/KBr system. It was observed that the ability of alcohol to induce micelle growth diminishes with n, which was well supported by viscosity, rheology and DLS measurements. To examine the effect of the electrolyte on the micellar growth, the salt concentration was varied from 0.05 to 0.15 M and it was observed that with increase in [KBr], the peak position shifts towards lower C0. The effect of temperature on the micellar system showed interesting phase behavior for CPC/KBr/Decanol. The system exhibited a closed solubility loop with an upper critical solution temperature (UCST) > the lower critical solution temperature (LCST), reminiscence of nicotine‐water system. The role of surfactant head group on the structural evolution was revealed by comparing the present results with our previous report for similar micellar system, CTAB/KBr/long chain alcohol.
Production of Biodiesel Using Liquid Lipase Formulations
Authors: Nielsen P. M. , Rancke‐Madsen A. , Holm H. C. , Burton R. 
Published: May 2016

AbstractLooking back at the literature for enzymatic biodiesel, it is evident that the research has been focused on using immobilized lipase to enable re‐use of the enzyme due to price constraints on lipases used for catalyzing the transesterification process. The use of liquid formulations of lipase for biodiesel has recently been implemented in the industry. Technology for using liquid formulated lipases for enzymatic biodiesel production is new and, since enzyme prices have been reduced, it is now possible to simplify the process considerably and apply it for very low‐quality oils. In this paper, the use of liquid lipase formulations for enzymatic biodiesel will be described along with a general proposal for an industrial‐scale enzymatic biodiesel process with >95 % yield.