bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optimal control design of turbo spin‐echo sequences with applications to parallel‐transmit systems
Authors: Sbrizzi Alessandro , Hoogduin Hans , Hajnal Joseph V. , van den Berg Cornelis A. T. , Luijten Peter R. , Malik Shaihan J. 
Published: January 2016

PurposeThe design of turbo spin‐echo sequences is modeled as a dynamic optimization problem which includes the case of inhomogeneous transmit radiofrequency fields. This problem is efficiently solved by optimal control techniques making it possible to design patient‐specific sequences online.Theory and MethodsThe extended phase graph formalism is employed to model the signal evolution. The design problem is cast as an optimal control problem and an efficient numerical procedure for its solution is given. The numerical and experimental tests address standard multiecho sequences and pTx configurations.ResultsStandard, analytically derived flip angle trains are recovered by the numerical optimal control approach. New sequences are designed where constraints on radiofrequency total and peak power are included. In the case of parallel transmit application, the method is able to calculate the optimal echo train for two‐dimensional and three‐dimensional turbo spin echo sequences in the order of 10 s with a single central processing unit (CPU) implementation. The image contrast is maintained through the whole field of view despite inhomogeneities of the radiofrequency fields.ConclusionThe optimal control design sheds new light on the sequence design process and makes it possible to design sequences in an online, patient‐specific fashion. Magn Reson Med 77:361–373, 2017. © 2016 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine
Neonatal vascularization and oxygen tension regulate appropriate perinatal renal medulla/papilla maturation
Authors: Phua Yu Leng , Gilbert Thierry , Combes Alexander , Wilkinson Lorine , Little Melissa H 
Published: January 2016

AbstractCongenital medullary dysplasia with obstructive nephropathy is a common congenital disorder observed in paediatric patients and represents the foremost cause of renal failure. However, the molecular processes regulating normal papillary outgrowth during the postnatal period are unclear. In this study, transcriptional profiling of the renal medulla across postnatal development revealed enrichment of non‐canonical Wnt signalling, vascular development, and planar cell polarity genes, all of which may contribute to perinatal medulla/papilla maturation. These pathways were investigated in a model of papillary hypoplasia with functional obstruction, the Crim1KST264/KST264 transgenic mouse. Postnatal elongation of the renal papilla via convergent extension was unaffected in the Crim1KST264/KST264 hypoplastic renal papilla. In contrast, these mice displayed a disorganized papillary vascular network, tissue hypoxia, and elevated Vegfa expression. In addition, we demonstrate the involvement of accompanying systemic hypoxia arising from placental insufficiency, in appropriate papillary maturation. In conclusion, this study highlights the requirement for normal vascular development in collecting duct patterning, development of appropriate nephron architecture, and perinatal papillary maturation, such that disturbances contribute to obstructive nephropathy. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Impact of Intraoperative Continuous‐Infusion Versus Intermittent Dosing of Cefazolin Therapy on the Incidence of Surgical Site Infections After Coronary Artery Bypass Grafting
Authors: Shoulders Bethany R. , Crow Jessica R. , Davis Stephanie L. , Whitman Glenn J. , Gavin Melanie , Lester Laeban , Barodka Viachaslau , Dzintars Kathryn 
Published: January 2016

Study ObjectivesTo determine whether intraoperative continuous‐infusion (CI) cefazolin reduces the incidence of surgical site infections (SSIs) compared with intermittent (INT) cefazolin dosing in patients undergoing coronary artery bypass grafting (CABG) on cardiopulmonary bypass (CPB); safety end points and protocol adherence comparing the two dosing strategies were also explored.DesignRetrospective quasi‐experimental (pre–post intervention) cohort study.SettingLarge academic medical center.PatientsA total of 516 adults who underwent CABG on CPB and received cefazolin intraoperatively between June 1, 2013, and December 31, 2014, were included. The INT cohort included 284 patients who underwent CABG from June 2013 to February 2014. The CI cohort included 232 patients who underwent CABG from April to December 2014, after an intraoperative CI cefazolin protocol for cardiac surgery patients undergoing CPB was adopted in March 2014.Measurements and Main ResultsThe primary end point was incidence of SSIs, and safety end points of renal dysfunction and seizures were evaluated. Multivariable logistic regression analysis was used to determine the impact on SSIs when controlling for other risk factors. A subgroup analysis for this study included 2 months within each time period to evaluate protocol adherence. The overall incidence of SSIs was decreased in patients receiving CI cefazolin, although this did not reach statistical significance (4.6% in the INT cohort vs 1.7% in the CI cohort, p=0.116). Superficial SSIs were significantly reduced in the CI cohort (2.8% in the INT cohort vs 0.4% in the CI cohort, p=0.039). In the regression analysis, CI cefazolin decreased the odds of SSI by 66%, although it did not reach statistical significance (p=0.077). Safety end points were not significantly different between groups. Overall protocol adherence did not differ significantly between the cohorts: 77% in the INT cohort and 67% in the CI cohort (p=0.212).ConclusionCI cefazolin significantly decreased the incidence of superficial SSIs compared with INT cefazolin in patients undergoing CABG on CPB, without increasing the risk for adverse effects. As this study was underpowered to detect a significant difference in overall SSIs, larger, randomized studies are required to validate the superiority of CI cefazolin.
Large area tunnel oxide passivated rear contact n‐type Si solar cells with 21.2% efficiency
Authors: Tao Yuguo , Upadhyaya Vijaykumar , Chen Chia‐Wei , Payne Adam , Chang Elizabeth Lori , Upadhyaya Ajay , Rohatgi Ajeet 
Published: January 2016

AbstractThis paper reports on the implementation of carrier‐selective tunnel oxide passivated rear contact for high‐efficiency screen‐printed large area n‐type front junction crystalline Si solar cells. It is shown that the tunnel oxide grown in nitric acid at room temperature (25°C) and capped with n+ polysilicon layer provides excellent rear contact passivation with implied open‐circuit voltage iVoc of 714 mV and saturation current density J0b′ of 10.3 fA/cm2 for the back surface field region. The durability of this passivation scheme is also investigated for a back‐end high temperature process. In combination with an ion‐implanted Al2O3‐passivated boron emitter and screen‐printed front metal grids, this passivated rear contact enabled 21.2% efficient front junction Si solar cells on 239 cm2 commercial grade n‐type Czochralski wafers. Copyright © 2016 John Wiley & Sons, Ltd.
Metal versus dielectric back reflector for thin‐film Si solar cells with impact of front electrode surface texture
Authors: Mercaldo Lucia V. , Usatii Iurie , Esposito Emilia M. , Delli Veneri Paola , Schüttauf Jan‐Willem , Moulin Etienne , Haug Franz‐Josef , Zhang Chao , Meier Matthias 
Published: January 2016

AbstractThin‐film Si solar cells employ a back reflector (BR) for a more efficient use of the long wavelength light. Here, we have carried out a cross evaluation of metal (Ag‐based) and dielectric (white paint‐based) BR designs. Conclusive results have been reached regarding the most suitable BR type depending on the front electrode morphology, both with crater‐like and pyramidal texture. The ZnO/Ag BR is found to be optically more efficient because of improved light trapping, although the gain tends to vanish for rougher front electrodes. Thanks to non‐conventional Raman intensity measurements, this dependence on the front texture has been linked to the different weight of front and back interfaces in the light trapping process for the different morphologies. With rougher substrates, because the minor optical gain is accompanied by sputter‐induced electronic deterioration of the solar cell during the ZnO buffer layer deposition, the white paint‐based BR design is preferred. Copyright © 2016 John Wiley & Sons, Ltd.
Molecular dynamics simulations of apo, holo, and inactivator bound GABA‐at reveal the role of active site residues in PLP dependent enzymes
Authors: Gökcan Hatice , Monard Gerald , Sungur Konuklar F. Aylin 
Published: January 2016

ABSTRACTThe pyridoxal 5‐phosphate (PLP) cofactor is a significant organic molecule in medicinal chemistry. It is often found covalently bound to lysine residues in proteins to form PLP dependent enzymes. An example of this family of PLP dependent enzymes is γ‐aminobutyric acid aminotransferase (GABA‐AT) which is responsible for the degradation of the neurotransmitter GABA. Its inhibition or inactivation can be used to prevent the reduction of GABA concentration in brain which is the source of several neurological disorders. As a test case for PLP dependent enzymes, we have performed molecular dynamics simulations of GABA‐AT to reveal the roles of the protein residues and its cofactor. Three different states have been considered: the apoenzyme, the holoenzyme, and the inactive state obtained after the suicide inhibition by vigabatrin. Different protonation states have also been considered for PLP and two key active site residues: Asp298 and His190. Together, 24 independent molecular dynamics trajectories have been simulated for a cumulative total of 2.88 µs. Our results indicate that, unlike in aqueous solution, the PLP pyridine moiety is protonated in GABA‐AT. This is a consequence of a pKa shift triggered by a strong charge–charge interaction with an ionic “diad” formed by Asp298 and His190 that would help the activation of the first half‐reaction of the catalytic mechanism in GABA‐AT: the conversion of PLP to free pyridoxamine phosphate (PMP). In addition, our MD simulations exhibit additional strong hydrogen bond networks between the protein and PLP: the phosphate group is held in place by the donation of at least three hydrogen bonds while the carbonyl oxygen of the pyridine ring interacts with Gln301; Phe181 forms a π–π stacking interaction with the pyridine ring and works as a gate keeper with the assistance of Val300. All these interactions are hypothesized to help maintain free PMP in place inside the protein active site to facilitate the second half‐reaction in GABA‐AT: the regeneration of PLP‐bound GABA‐AT (i.e., the holoenzyme). Proteins 2016; 84:875–891. © 2016 Wiley Periodicals, Inc.
Leaf‐morphology‐assisted selection for resistance to two‐spotted spider mite Tetranychus urticae Koch (Acari: Tetranychidae) in carnations (Dianthus caryophyllus L)
Authors: Seki Kousuke 
Published: January 2016

AbstractBACKGROUNDThe development of a cultivar resistant to the two‐spotted spider mite has provided both ecological and economic benefits to the production of cut flowers. This study aimed to clarify the mechanism of resistance to mites using an inbred population of carnations.RESULTSIn the resistant and susceptible plants selected from an inbred population, a difference was recognised in the thickness of the abaxial palisade tissue by microscopic examination of the damaged leaf. Therefore, it was assumed that mites displayed feeding preferences within the internal leaf structure of the carnation leaf. The suitability of the host plant for mites was investigated using several cultivars selected using an index of the thickness from the abaxial leaf surface to the spongy tissue. The results suggested that the cultivar associated with a thicker abaxial tissue lowered the intrinsic rate of natural increase of the mites. The cultivars with a thicker abaxial tissue of over 120 µm showed slight damage in the field test.CONCLUSIONThe ability of mites to feed on the spongy tissue during an early life stage from hatching to adult emergence was critical. It was possible to select a cultivar that is resistant to mites under a real cultivation environment by observing the internal structure of the leaf. © 2016 Society of Chemical Industry
The use of substituted alkynyl phenoxy derivatives of piperonyl butoxide to control insecticide‐resistant pests
Authors: Philippou Despina , Borzatta Valerio , Capparella Elisa , Moroni Leni , Field Linda , Moores Graham 
Published: January 2016

AbstractBACKGROUNDDerivatives of piperonyl butoxide with alkynyl side chains were tested in vitro and in vivo against pyrethroid‐resistant Meligethes aeneus and imidacloprid‐resistant Myzus persicae.RESULTSSynergists with the alkynyl side chain were more effective inhibitors of P450 activity in vitro than piperonyl butoxide, and demonstrated high levels of synergism in vivo, with up to 290‐fold synergism of imidacloprid against imidacloprid‐resistant M. persicae.CONCLUSIONSThese ‘second‐generation’ synergists could overcome metabolic resistance in many pest species and possibly enable reduced rates of insecticide application in some cases. © 2016 Society of Chemical Industry
Testing particle filters on simple convective‐scale models Part l: A stochastic cloud model
Authors: Haslehner Mylène , Janjić Tijana , Craig George C. 
Published: January 2016

Convective‐scale applications require data assimilation methods that can cope with nonlinear dynamics and the stochastic nature of convection. For this application, the particle filter is a promising data assimilation method because it estimates the probability density function (PDF) of the atmospheric state and not only its first two moments. However, in order to represent PDFs with a small number of particles, the particle filter is usually combined with another data assimilation technique. In this article we investigate a hybrid algorithm, the nudging proposal particle filter, which combines the sequential importance resampling particle filter with nudging.Analytic and experimental results on an idealized, nonlinear, one‐dimensional model are used to show that there exists a combination of the two methods such that the nudging proposal particle filter outperforms both of its components. In this article, a stochastic cloud model, represented through a birth–death process, serves as a first test model for the filter. The transition probability density can be calculated exactly for this model, thus providing insight into its contribution to the selection of particles during resampling. The functioning mechanism of the nudging proposal particle filter in its simplest form is investigated and the impact of the model parameters on the filter's behaviour highlighted.
The annual cycle of the West African monsoon in a two‐dimensional model: mechanisms of the rain‐band migration
Authors: Peyrillé P. , Lafore J.‐P. , Boone A. 
Published: January 2016

The processes that drive the annual cycle of the West African Monsoon (WAM) are analysed using an idealized meridional–vertical numerical model that includes moist physics. Using the work by Peyrillé and Lafore (2007) as a starting point, the framework has been adapted to studying the annual cycle. A suitable forcing methodology for temperature and humidity has been derived which allows the two‐dimensional model to reproduce the main features of the WAM.A budget analysis of the simulated temperature and humidity variables leads to a picture of the intertropical convergence zone (ITCZ) seasonal displacement, for which the moistening on the northern side of the ITCZ is a key. It is due to the near‐surface moisture advection by the monsoon flow to the north of the ITCZ, in addition to the turbulent fluxes and shallow convection, which transport moisture to the top of the planetary boundary layer. On a larger scale, the warming of the Saharan heat‐low by turbulence and radiation and the cooling/moistening within the ITCZ by convective downdraughts reinforces the monsoon flow. Inertial instability is also at play favouring the acceleration of the monsoon flow and the associated humidification. These mechanisms seem to be at play during the whole seasonal cycle, which is seen as a steady translation of these structures.Sensitivity experiments show the importance of the low‐level processes such as downdraughts, horizontal advection and water recycling. Although advection is the first‐order process, the water recycling appears as a key element by directly modulating the intensity of rainfall and by allowing the convective downdraughts to feed back onto the WAM.
Bayesian methods of confidence interval construction for the population attributable risk from cross‐sectional studies
Authors: Pirikahu Sarah , Jones Geoffrey , Hazelton Martin L. , Heuer Cord 
Published: January 2016

Population attributable risk measures the public health impact of the removal of a risk factor. To apply this concept to epidemiological data, the calculation of a confidence interval to quantify the uncertainty in the estimate is desirable. However, because perhaps of the confusion surrounding the attributable risk measures, there is no standard confidence interval or variance formula given in the literature. In this paper, we implement a fully Bayesian approach to confidence interval construction of the population attributable risk for cross‐sectional studies. We show that, in comparison with a number of standard Frequentist methods for constructing confidence intervals (i.e. delta, jackknife and bootstrap methods), the Bayesian approach is superior in terms of percent coverage in all except a few cases. This paper also explores the effect of the chosen prior on the coverage and provides alternatives for particular situations. Copyright © 2016 John Wiley & Sons, Ltd.
Kinetic modeling and long‐term test‐retest reproducibility of the mGluR5 PET tracer 18F‐FPEB in human brain
Authors: Leurquin‐Sterk Gil , Postnov Andrey , de Laat Bart , Casteels Cindy , Celen Sofie , Crunelle Cleo L. , Bormans Guy , Koole Michel , Van Laere Koen 
Published: January 2016

ABSTRACT18F‐FPEB is a promising PET tracer for studying the metabotropic glutamate subtype 5 receptor (mGluR5) expression in neuropsychiatric disorders. To assess the potential of 18F‐FPEB for longitudinal mGluR5 evaluation in patient studies, we evaluated the long‐term test‐retest reproducibility using various kinetic models in the human brain. Nine healthy volunteers underwent consecutive scans separated by a 6‐month period. Dynamic PET was combined with arterial sampling and radiometabolite analysis. Total distribution volume (VT) and nondisplaceable binding potential (BPND) were derived from a two‐tissue compartment model without constraints (2TCM) and with constraining the K1/k2 ratio to the value of either cerebellum (2TCM‐CBL) or pons (2TCM‐PONS). The effect of fitting different functions to the tracer parent fractions and reducing scan duration were assessed. Regional absolute test‐retest variability (aTRV), coefficient of repeatability (CR) and intraclass correlation coefficient (ICC) were computed. The 2TCM‐CBL showed best fits. The mean 6‐month aTRV of VT ranged from 8 to 13% (CR < 25%) with ICC > 0.6 for all kinetic models. BPND from 2TCM‐CBL with a sigmoid fit for the parent fractions showed the best reproducibility, with aTRV ≤ 7% (CR < 16%) and ICC > 0.9 in most regions. Reducing the scan duration from 90 to 60 min did not affect reproducibility. These results demonstrate for the first time that 18F‐FPEB brain PET has good long‐term reproducibility, therefore validating its use to monitor mGluR5 expression in longitudinal clinical studies. We suggest a 2TCM‐CBL with fitting a sigmoid function to the parent fractions to be optimal for this tracer. Synapse, 2016. © 2016 Wiley Periodicals, Inc. Synapse 70:153–162, 2016. © 2016 Wiley Periodicals, Inc.
An acute, epitope‐specific modification in the dopamine transporter associated with methamphetamine‐induced neurotoxicity
Authors: Fricks‐Gleason Ashley N. , German Christopher L. , Hoonakker Amanda J. , Friend Danielle M. , Ganesh Kamala K. , Carver Aaron S. , Hanson Glen R. , Fleckenstein Annette E. , Keefe Kristen A. 
Published: January 2016

ABSTRACTPreclinical studies demonstrate that repeated, high‐dose methamphetamine administrations rapidly decrease plasmalemmal dopamine uptake, which may contribute to aberrant dopamine accumulation, reactive species generation, and long‐term dopaminergic deficits. The present study extends these findings by demonstrating a heretofore unreported, epitope‐specific modification in the dopamine transporter caused by a methamphetamine regimen that induces these deficits. Specifically, repeated, high‐dose methamphetamine injections (4 × 10 mg/kg/injection, 2‐h intervals) rapidly decreased immunohistochemical detection of striatal dopamine transporter as assessed 1 h after the final methamphetamine exposure. In contrast, neither a single high dose (1 × 10 mg/kg) nor repeated injections of a lower dose (4 × 2 mg/kg/injection) induced this change. The high‐dose regimen‐induced alteration was only detected using antibodies directed against the N‐terminus. Immunohistochemical staining using antibodies directed against the C‐terminus did not reveal any changes. The high‐dose regimen also did not alter dopamine transporter expression as assessed using [125I]RTI‐55 autoradiography. These data suggest that the repeated, high‐dose methamphetamine regimen alters the N‐terminus of the dopamine transporter. Further, these data may be predictive of persistent dopamine deficits caused by the stimulant. Future studies of the signaling cascades involved should provide novel insight into potential mechanisms underlying the physiological and pathophysiological regulation of the dopamine transporter. Synapse, 2016. © 2016 Wiley Periodicals, Inc. Synapse 70:139–146, 2016. © 2016 Wiley Periodicals, Inc.
New Portal‐Superior Mesenteric Vein Reconstructions Using First Jejunal Vein Flap in Pancreaticoduodenectomy
Authors: Takemura Nobuyuki , Miki Kenji , Kosuge Tomoo 
Published: January 2016

AbstractPancreaticoduodenectomy (PD) is the only potential treatment for pancreatic head adenocarcinomas, which are sometimes located close to or invade the portal‐superior mesenteric vein (PSMV). Surgeons often attempt to obtain a negative resectional margin after resection of the PSMV. This attempt requires PSMV reconstruction through graft replacements or end‐to‐end anastomosis; however, possible complications should be concerned including anastomosis stenosis, damage to some of the PSMV branches, prosthetic graft infection, and that associated with autologous graft harvesting. The first jejunal artery and vein are often resected in PD with the intent of lymphadenectomy. In this study, jejunal vein flap was used for PSMV reconstruction without causing damage to any of the PSMV branches in two patients. Here, we describe the new methods of PSMV reconstruction using first jejunal vein flap in PD.