bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ursodeoxycholic acid treatment of hepatic steatosis: a 13C NMR metabolic study
Authors: Nunes Patrícia M. , Jones John G. , Rolo Anabela P. , Palmeira Carlos M. M. , Carvalho Rui A. 
Published: April 2011

AbstractUrsodeoxycholic acid (UDCA) is commonly used for the treatment of hepatobiliary disorders. In this study, we tested whether a 4‐week treatment with this bile acid (12–15 mg/kg/day) could improve hepatic fatty acid oxidation in obese Zucker rats – a model for nonalcoholic fatty liver disease and steatosis. After 24 h of fasting, livers were perfused with physiological concentrations of [U‐13C]nonesterified fatty acids and [3‐13C]lactate/[3‐13C]pyruvate. Steatosis was associated with abundant intracellular glucose, lactate, alanine and methionine, and low concentrations of choline and betaine. Steatotic livers also showed the highest output of glucose and lactate. Glucose and glycolytic products were mostly unlabeled, indicating active glycogenolysis and glycolysis after 24 h of fasting. UDCA treatment resulted in a general amelioration of liver metabolic abnormalities with a decrease in intracellular glucose and lactate, as well as their output. Hepatic betaine and methionine were also normalized after UDCA treatment, suggesting the amelioration of anti‐oxidative defenses. Choline levels were not affected by the bile acid, which may indicate a deficient synthesis of very‐low‐density lipoproteins. The percentage contribution of [U‐13C]nonesterified fatty acids to acetyl‐coenzyme A entering the tricarboxylic acid (TCA) cycle was significantly lower in livers from Zucker obese rats relative to control rats: 23.1 ± 4.9% versus 44.1 ± 2.7% (p < 0.01). UDCA treatment did not alter significantly fatty acid oxidation in control rats, but improved significantly oxidation in Zucker obese rats to 46.0 ± 6.1% (p > 0.05), comparable with control group values. The TCA cycle activity subsequent to fatty acid oxidation was reduced in steatotic livers and improved when UDCA was administered (0.24 ± 0.04 versus 0.37 ± 0.05, p = 0.05). We further suggest that the mechanism of action of UDCA is either related to the activity of the farnesoid receptor, or to the amelioration of the anti‐oxidative defenses and cell nicotinamide adenine dinucleotide (NAD+/NADH) ratio, favoring TCA cycle activity and β‐oxidation. Copyright © 2011 John Wiley & Sons, Ltd.
Topology optimization of planar shape memory alloy thermal actuators using element connectivity parameterization
Authors: Langelaar M. , Yoon G. H. , Kim Y. Y. , van Keulen F. 
Published: April 2011

AbstractThis paper presents the direct application of topology optimization to the design of shape memory alloy (SMA) thermal actuators. Because SMAs exhibit strongly nonlinear, temperature‐dependent material behavior, designing effective multidimensional SMA actuator structures is a challenging task. We pursue the use of topology optimization to address this problem. Conventional material scaling topology optimization approaches are hampered by the complexity of the SMA constitutive behavior combined with large actuator deflections. Therefore, for topology optimization we employ the element connectivity parameterization approach, which offers improved analysis convergence and robustness, as well as an unambiguous treatment of nonlinear materials. A path‐independent SMA constitutive model, aimed particularly at the NiTi R‐phase transformation, is employed, allowing efficient adjoint sensitivity analysis. The effectiveness of the proposed SMA topology optimization is demonstrated by numerical examples of constrained and unconstrained formulations of actuator stroke maximization, which provide insight into the characteristics of optimal SMA actuators. Copyright © 2011 John Wiley & Sons, Ltd.
Deflated preconditioned conjugate gradient solvers for linear elasticity
Authors: Aubry R. , Mut F. , Dey S. , Löhner R. 
Published: April 2011

AbstractExtensions of deflation techniques previously developed for the Poisson equation to static elasticity are presented. Compared to the (scalar) Poisson equation (J. Comput. Phys. 2008; 227(24):10196–10208; Int. J. Numer. Meth. Engng 2010; DOI: 10.1002/nme.2932; Int. J. Numer. Meth. Biomed. Engng 2010; 26(1):73–85), the elasticity equations represent a system of equations, giving rise to more complex low‐frequency modes (Multigrid. Elsevier: Amsterdam, 2000). In particular, the straightforward extension from the scalar case does not provide generally satisfactory convergence. However, a simple modification allows to recover the remarkable acceleration in convergence and CPU time reached in the scalar case. Numerous examples and timings are provided in a serial and a parallel context and show the dramatic improvements of up to two orders of magnitude in CPU time for grids with moderate graph depths compared to the non‐deflated version. Furthermore, a monotonic decrease of iterations with increasing subdomains, as well as a remarkable acceleration for very few subdomains are also observed if all the rigid body modes are included. Copyright © 2011 John Wiley & Sons, Ltd.
Efficient calibration of the Hull White model
Authors: Schlenkrich Sebastian 
Published: April 2011

SUMMARYIn this paper we study the calibration of the Hull White interest rate model for the pricing of Bermudan swaptions and Bermudan bond options. A common modelling approach for the calibration of the Hull White model is to choose the model parameters such that market prices of corresponding European derivatives are replicated by the model. This requires that a multidimensional non‐linear optimization problem has to be solved. The focus of this paper lies in the efficient formulation and numerical solution of this optimization problem. We investigate the numerical properties of the iterative solution of the optimization problem by means of a Gauss Newton and an Adjoint Broyden quasi‐Newton method. Required derivatives of the objective function are evaluated by techniques of Automatic Differentiation. The algorithms are benchmarked to Minpack's general purpose solver HYBRD. Numerical results for the calibration of long‐term Bermudan swaptions are reported. Copyright © 2011 John Wiley & Sons, Ltd.
Design of sliding mode control for neutral delay systems with perturbation in control channels
Authors: Niu Yugang , Jia T. , Huang J. , Liu J. 
Published: April 2011

SUMMARYThis paper considers the problem of sliding mode control for a class of uncertain neutral delay systems. There are uncertainties not only in the state matrices, but also in the control matrix that results from perturbation in the control channels. By means of a sliding surface dependent on both the current states and delayed states, a sliding mode controller is designed such that the asymptotic stability of closed‐loop systems can be ensured. The design of both the sliding surface and the sliding mode controller can be obtained via convex optimization. It is shown that the state trajectories are driven onto the specified sliding surface in finite time and remain there for subsequent time. Finally, a numerical simulation example is provided. Copyright © 2011 John Wiley & Sons, Ltd.
Toward a generalized sub‐optimal control method of underactuated systems
Authors: Ordaz‐Oliver J. Patricio , Santos‐Sánchez Omar J. , López‐Morales Virgilio 
Published: April 2011

SUMMARYIn this paper, some experimental results and a performance analysis of a general control methodology for swinging up and stabilizing underactuated two‐link robots are presented. The analyzed methodology is based on Euler–Lagrange dynamics, passivity analysis, and dynamic programming theory. The applied control method preserves the general structure of a suboptimal control approach, while the functional defining a performance index is based on the underactuated system energy. In order to illustrate the presented approach, the swing up and stabilization control of two experimental electromechanical underactuated systems about an unstable equilibrium point are shown. Copyright © 2011 John Wiley & Sons, Ltd.
Thermal properties and stability of n‐octadecane based composites containing multiwalled carbon nanotubes
Authors: Bayramoglu Evren Çagˇlim 
Published: April 2011

AbstractIn this study, multiwalled carbon nanotubes (MWNT) were added to n‐octadecane at weight percentages of 1.25, 2.5, 5, 10 and changes of thermal properties of n‐octadecane were analyzed. Structural characterization of the materials was carried out by transmission electron microscope (TEM) and optical microscope. Thermal properties of n‐octadecane and its composites were evaluated through differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The thermal measurements show that the highest contribution to latent heat absorbing capacity with 18% was provided by the addition of 1.25% MWNT to n‐octadecane. The thermal properties and the thermal stability of pure n‐octadecane and its composites with MWNT were also investigated by subjecting the samples to 1440 melting‐cooling cycles. The sample with 1.25% MWNT content also showed the best thermal stability. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers
Off‐label prescribing patterns of antidepressants in children and adolescents
Authors: Lee Euni , Teschemaker Anna R. , Johann‐Liang Rosemary , Bazemore Gina , Yoon Martin , Shim Kye‐Sik , Daniel Marlon , Pittman Jerome , Wutoh Anthony K. 
Published: April 2011

ABSTRACTPurposeTo understand the extent of off‐label prescribing among pediatrics, the study assesses the prescribing patterns of antidepressants in ambulatory settings.MethodsA cross‐sectional analysis was conducted using the National Ambulatory Medical Care Survey from 2000 to 2006. The prevalence of off‐label prescribing of antidepressants was estimated, and predictive factors were evaluated.ParticipantsChildren and adolescents aged 6–18 years to private physicians' offices.Main Outcome MeasuresPrevalence of antidepressant prescriptions including FDA and non‐FDA‐approved indications, types of antidepressants prescribed, and factors associated with off‐label prescribing.ResultsOur study population made 18 646 visits to private physicians' offices, representing about 667 million weighted visits during the study period. The mean age of the patients was 12.2 years (SD = 3.7), and majority of the visits were made by White people (73.1%). Of all visits, 3.7% (95%CI: 3.2%–4.2%) were associated with antidepressants. The most prevalent form of antidepressants prescribed were selective serotonin reuptake inhibitors (63.7%). Only 9.2% of the visits were associated with FDA‐approved indications. Visits made to pediatricians (adjusted OR = 2.4; 95%CI: 1.1–5.1), family physicians, and other offices (adjusted OR = 1.9; 95%CI: 1.2–3.1) were more likely to be associated with off‐label prescribing as compared with visits to a psychiatrist's office.ConclusionsThe study observed a very high prevalence of off‐label antidepressant prescribing patterns among children and adolescents in US ambulatory care settings. Coordinated efforts should be placed to evaluate the potential reasons and ramifications of antidepressant off‐label prescribing to guard patients' safety. Copyright © 2011 John Wiley & Sons, Ltd.
Zwitterionic shell‐crosslinked micelles from block‐comb copolymer of PtBA‐b‐P(PEGMEMA‐co‐DMAEMA)
Authors: Ding Zong‐Lei , He Wei‐Dong , Tao Jing , Jiang Wen‐Xing , Li Li‐Ying , Pan Ting‐Ting 
Published: April 2011

AbstractThrough reversible addition‐fragmentation chain transfer (RAFT) polymerization of t‐butyl acrylate (tBA) and RAFT copolymerization of 2‐dimethylaminoethyl methacrylate (DMAEMA) with poly(ethylene glycol) methyl ether methacrylate (PEGMEMA), block‐comb copolymer of PtBA‐b‐P(PEGMEMA‐co‐DMAEMA) was prepared. After the self‐assembly of PtBA‐b‐P(PEGMEMA‐co‐DMAEMA) into core‐shell spherical micelles, P(PEGMEMA‐co‐DMAEMA) segments of the shell was crosslinked with 1,2‐bis(2‐iodoethoxy)ethane and the core of PtBA was selectively hydrolysized with trifluoroacetic acid. Thus, zwitterionic shell‐crosslinked micelles with positively charged outer shell and negatively charged inner core were obtained. Dynamic light scattering, transmission electron microscope, Zeta potential measurement, and nuclear magnetic resonance were used to confirm the formation of the zwitterionic shell‐crosslinked micelles. They showed the excellent resistance to the variation of pH value and possessed the positive values throughout the whole range of pH range even if the carboxylic groups of the micelles was much more than ammonium groups. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Main‐chain chiral poly(2‐oxazoline)s: Influence of alkyl side‐chain on secondary structure formation in solution
Authors: Bloksma Meta M. , Rogers Sarah , Schubert Ulrich S. , Hoogenboom Richard 
Published: April 2011

AbstractThe synthesis and microwave‐assisted polymerization of a series of chiral 2‐oxazolines with varying alkyl pendant groups, namely R‐2‐ethyl‐4‐ethyl‐2‐oxazoline (R‐EtEtOx), R‐2‐butyl‐4‐ethyl‐2‐oxazoline (R‐BuEtOx), R‐2‐octyl‐4‐ethyl‐2‐oxazoline, 2‐nonyl‐4‐ethyl‐2‐oxazoline, and R‐2‐undecyl‐4‐ethyl‐2‐oxazoline (R‐UndeEtOx), are reported. A kinetic investigation of the polymerization of R‐EtEtOx revealed a living polymerization mechanism. The poly(2‐oxazoline)s containing an ethyl, butyl, and octyl pendant group form similar chiral structures according to circular dichroism measurements. When the pendant group is further elongated, the chiral structure becomes more flexible in trifluoroethanol and the thermal response in hexafluoroisopropanol (HFIP) significantly changes. The short‐range structure of poly‐R‐BuEtOx dissolved in HFIP is thermoresponsive in a complex way, due to HFIP hydrogen bonding to the polymeric amide groups, whereas the long‐range structure determined from small angle neutron scattering is insensitive to temperature demonstrating that only the local secondary structure changes with temperature. In addition, the chiral structure of poly‐R‐UndeEtOx depends on the polarity of the solvent. The short‐range structure becomes more flexible in polar solvents, most likely due to interactions with the amide groups disturbing the secondary structure. In contrast, the long‐range structural transition from an ellipsoid in the apolar n‐hexane to a rod structure in the polar n‐butanol is ascribed to better solvation of the long aliphatic side chains. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Mass spectrometric immunoassay of intact insulin and related variants for population proteomics studies
Authors: Oran Paul E. , Jarvis Jason W. , Borges Chad R. , Sherma Nisha D. , Nelson Randall W. 
Published: April 2011

AbstractPurpose: The purpose of the work presented herein was to develop a high‐throughput assay for the quantification of human insulin in plasma samples while simultaneously detecting, with high mass accuracy, any additional variant forms of insulin that might be present in each sample.Experimental design: A mass spectrometric immunoassay (MSIA) was designed in which anti‐human insulin antibodies were immobilized to commercially available mass spectrometric immunoassay pipette tips and used to capture insulin and related protein variants from human plasma.Results: Standard curves for insulin exhibited linearity (average R2 for three days of analysis=0.99) and assay concentration limits of detection and limits of quantification for insulin were found to be 1 and 15 pM, respectively. Estimated coefficient of variations for inter‐day experiments (n=3 days) were <8%. Simultaneously, the assay was shown to detect and identify insulin metabolites and synthetic insulin analogs (e.g. Lantus). Notably, insulin variants not known to exist in plasma were detected in diabetics.Conclusions and clinical relevance: This introductory study sets a foundation toward the screening of large populations to investigate insulin isoforms, isoform frequencies, and their quantification.
Silver‐induced conformational changes of polypeptides: a CD study
Authors: Murariu Manuela , Stela Dragan Ecaterina , Adochitei Adriana , Zbancioc Gheorghita , Drochioiu Gabi 
Published: April 2011

AbstractThe role of silver ions in various pathologies, as well as their effect on peptide conformation and properties are less understood. Consequently, we synthesized several peptides with various residues in their sequence to investigate silver‐induced conformational changes at various pH values by Circular Dichroism spectroscopy. Uniquely, the glycine‐based, histidine‐containing peptide showed a severe change from a random coil and β‐turn conformation to large α‐helices during silver binding. When comparing the effect of silver ions on the conformation of bradykinin a similar tendency was found. Besides, silver ions reduced the amyloid‐β peptide tendency to aggregation. Our results suggest a specific and protective role for silver ions in brain pathologies, which is related to their high affinity toward physiologically and pharmacologically active peptides. Fourier transform infrared spectroscopy studies as well as the mass spectrometric ones support our conclusions. Copyright © 2011 European Peptide Society and John Wiley & Sons, Ltd.
Conformational constraints in angiotensin IV to probe the role of Tyr2, Pro5 and Phe6
Authors: Lukaszuk Aneta , Demaegdt Heidi , Van den Eynde Isabelle , Vanderheyden Patrick , Vauquelin Georges , Tourwé Dirk 
Published: April 2011

AbstractThe aromatic amino acids Tyr and Phe in angiotensin IV (Ang IV) were conformationally constrained by the use of β‐Me substituted analogs, or cyclic constrained analogs. None of these modifications was allowed for Tyr1, while only e‐β‐MePhe6 substitution resulted in an AngIV analog with high IRAP potency and selectivity versus AP‐N or the AT1 receptor. This indicates an important role of the orientation of the Phe6 for inducing selectivity. Pro5 replacement with 2‐aminocyclopentanecarboxylic acid maintained IRAP potency and abolished AT1 affinity. These results confirm the importance of conformational constrained amino acids to generate selectivity in bioactive peptides. Copyright © 2011 European Peptide Society and John Wiley & Sons, Ltd.
Assessment of numerical weather forecasts against observations from Cardington: seasonal diurnal cycles of screen‐level and surface temperatures and surface fluxes
Authors: Edwards J. M. , McGregor J. R. , Bush M. R. , Bornemann F. J. 
Published: April 2011

AbstractThe performance of numerical weather forecasts made with the Met Office Unified Model is evaluated using near‐surface measurements made at a comprehensively instrumented site over the course of the annual cycle, with the aim of characterizing the forecasting system's generic behaviour in the surface layer. The study is focused on the seasonal diurnal cycles of the screen‐level and surface temperatures and the surface flux budget.High‐resolution versions of the model simulate seasonal composite diurnal cycles of the screen temperature to an accuracy of about 1 K, but appear to show a cold bias in the surface skin temperature by day and a warm bias at night, while underestimating the magnitude of the difference in temperature between the screen level and the surface, particularly in conditions of light winds and strong surface cooling.The consistency of the measured surface fluxes is assessed by deriving the full annual cycle of the monthly mean atmospheric surface fluxes. The measured surface flux budget at this site is closed to an accuracy better than 5 W m−2. Comparison of the modelled and measured fluxes shows that in spring and summer the modelled downward shortwave fluxes are too large, while the latent heat fluxes are overestimated. Copyright © 2011 British Crown Copyright. Published by John Wiley & Sons Ltd.
The ERA‐Interim reanalysis: configuration and performance of the data assimilation system
Authors: Dee D. P. , Uppala S. M. , Simmons A. J. , Berrisford P. , Poli P. , Kobayashi S. , Andrae U. , Balmaseda M. A. , Balsamo G. , Bauer P. , Bechtold P. , Beljaars A. C. M. , van de Berg L. , Bidlot J. , Bormann N. , Delsol C. , Dragani R. , Fuentes M. , Geer A. J. , Haimberger L. , Healy S. B. , Hersbach H. , Hólm E. V. , Isaksen L. , Kållberg P. , Köhler M. , Matricardi M. , McNally A. P. , Monge‐Sanz B. M. , Morcrette J.‐J. , Park B.‐K. , Peubey C. , de Rosnay P. , Tavolato C. , Thépaut J.‐N. , Vitart F. 
Published: April 2011

AbstractERA‐Interim is the latest global atmospheric reanalysis produced by the European Centre for Medium‐Range Weather Forecasts (ECMWF). The ERA‐Interim project was conducted in part to prepare for a new atmospheric reanalysis to replace ERA‐40, which will extend back to the early part of the twentieth century. This article describes the forecast model, data assimilation method, and input datasets used to produce ERA‐Interim, and discusses the performance of the system. Special emphasis is placed on various difficulties encountered in the production of ERA‐40, including the representation of the hydrological cycle, the quality of the stratospheric circulation, and the consistency in time of the reanalysed fields. We provide evidence for substantial improvements in each of these aspects. We also identify areas where further work is needed and describe opportunities and objectives for future reanalysis projects at ECMWF. Copyright © 2011 Royal Meteorological Society
Highly correlated calculations using optimized virtual orbital space with controlled accuracy. Application to counterpoise corrected interaction energy calculations
Authors: Kraus Michal , Pitoňák Michal , Hobza Pavel , Urban Miroslav , Neogrády Pavel 
Published: April 2011

AbstractIn this work, we investigate the correlation between error introduced by truncation of optimized virtual orbital space (OVOS) on the MP2 level (YMP2) with the error of the post‐MP2 contributions, such as the CCSD‐MP2 (i.e., YΔCCSD), CCSD(T)‐MP2 (i.e., YΔCCSD(T)), or the (T) separately. We found a correlation between the YMP2 and several other quantities, such as the percent of recovered optimization functional value in the truncated OVOS (OF%), or the aforementioned YΔCCSD, YΔCCSD(T), Y(T), which is to good approximation linear in the logarithmic scale. These correlations open a possibility to control the accuracy of the post‐MP2 calculations in the truncated OVOS, because the YMP2 and the OF% are easily obtained, almost as a byproduct of the virtual orbital optimization. According to the results present in this work, knowledge of the YMP2 or the OF% allows us to safely estimate the order of magnitude of the error of the post‐MP2 corrections. To keep the accuracy of, for instance, CCSD(T) correlation energy calculated in the truncated OVOS within 1.10−5 − 1.10−6 Hartree error bars, we can typically reduce only a few percent of the OVOS, although this value increases slightly with enlarging the atomic orbital (AO) basis set and the number of inactive occupied orbitals. Still, even such a modest reduction can save more then a half of the computation time, compared with calculations in the full VOS. The situation is, however, much more favourable in case of counterpoise (CP) corrected calculations of interaction energy, where this methodology enables safe truncation of significant part of OVOS of monomers, resulting from the presence of the ghost AO. Dimension of such truncated OVOS essentially corresponds to CP‐uncorrected calculations, thus leads to more than an order of magnitude speedup of calculation of monomers. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012