bluuebunny/crossref_metadata_2025_split huggingface dataset:
A test of comparative equilibration for determining non‐exchangeable stable hydrogen isotope values in complex organic materials
Authors: Kelly Jeffrey F. , Bridge Eli S. , Fudickar Adam M. , Wassenaar Leonard I. 
Published: July 2009

AbstractComparative equilibration has been proposed as a methodological approach for determining the hydrogen isotopic composition (δD) of non‐exchangeable hydrogen in complex organic materials, from feathers to blood and soils. This method depends on using homogenized standards that have been previously calibrated for their δD values of non‐exchangeable H, that are compositionally similar to unknown samples, and that span an appropriate isotopic range. Currently no certified organic reference materials with exchangeable H exist, and so isotope laboratories have been required to develop provisional internal calibration standards, such as the keratin standards currently used in animal migration studies. Unfortunately, the isotope ratios of some samples fall outside the range of keratin standards currently used for comparative equilibration. Here we tested a set of five homogenized keratin powders as well as feathers from Painted Buntings and Dark‐eyed Juncos to determine the effects of extrapolating comparative equilibration normalization equations outside the isotopic range of keratin standards. We found that (1) comparative equilibration gave precise results within the range of the calibration standards; (2) linear extrapolation of normalization equations produced accurate δD results to ∼40‰ outside the range of the keratins standards used (−187 to −108); and (3) for both homogenized keratin powders and heterogeneous unknown samples there was no difference in variance between samples within and outside the range of keratin standards. This suggested that comparative equilibration is a robust and practical method for determining the δD of complex organic matrices, although caution is required for samples that fall far outside the calibration range. Copyright © 2009 John Wiley & Sons, Ltd.
Energy‐resolved depth profiling of metal‐polymer interfaces using dynamic quadrupole secondary ion mass spectrometry
Authors: Téllez Helena , Vadillo José M. , Laserna J. Javier 
Published: July 2009

AbstractQuadrupole secondary ion mass spectrometry (qSIMS) characterization of a metallized polypropylene film used in the manufacturing of capacitors has been performed. Ar+ primary ions were used to preserve the oxidation state of the surface. The sample exhibits an incomplete metallization that made it difficult to determine the exact location of the metal‐polymer interface due to the simultaneous contribution of ions with identical m/z values from the metallic and the polymer layers. Energy filtering by means of a 45° electrostatic analyzer allowed resolution of the metal‐polymer interface by selecting a suitable kinetic energy corresponding to the ions generated in the metallized layer but not from the polymer. Under these conditions, selective analyses of isobaric interferences such as 27Al+ and 27C2H or 43AlO+ and 43C3H have been successfully performed. Copyright © 2009 John Wiley & Sons, Ltd.
Searching forin silicopredicted metabolites and designer modifications of (cortico)steroids in urine by high‐resolution liquid chromatography/time‐of‐flight mass spectrometry
Authors: Peters Ruud J. B. , van Engelen Marcel C. , Touber Manja E. , Georgakopoulus Costas , Nielen Michel W. F. 
Published: July 2009

AbstractGlucocorticosteroids are a restricted class of substances and appear on the ‘in‐competition’ prohibited list of the World Anti‐Doping Agency (WADA). Analysis of glucocorticosteroids is complicated since they show significant phase 1 and 2 metabolism in the human body and are excreted into urine in concentrations in the µg/L range. Full scan, high‐resolution time‐of‐flight mass spectrometry analysis generates information on all ionisable components in urine, including known and unknown metabolites of steroids and even designer modifications of anabolic steroids. However, evaluation of the data obtained can be difficult and time‐consuming because of the need to differentiate between endogenous components and compounds of interest. MetaboLynx™, a spectral and chromatographic search program, was modified for the determination ofin silicopredicted metabolites of glucocorticosteroids and designer modifications of anabolic steroids in human urine. Spiked urine samples were successfully screened for known components in a targeted approach and for unknown species in a non‐targeted approach using data filtering to limit potential false‐positives. A simplified combined approach of targeted and untargeted screening was used for the detection of metabolites and designer modifications of existing compounds. This approach proved successful and showed its strength in the detection of tetrahydrogestrinone (THG), a designer modification of gestrinone. THG was positively detected in a spiked urine sample and correctly identified as a twofold hydrogenation of gestrinone. The developed screening method can easily be adapted to specific needs and it is envisaged that a similar approach would be amendable to the discovery of metabolites or designer modifications of other compounds of interest. Copyright © 2009 John Wiley & Sons, Ltd.
Muscle and scale isotopic offset of three fish species in the Mediterranean Sea: Dentex dentex, Argyrosomus regius and Xyrichtys novacula
Authors: Blanco A. , Deudero S. , Box A. 
Published: July 2009

AbstractDiet information of organisms was traditionally acquired by the use of lethal techniques (gut content or muscle δ13C and δ15N isotopic ratios). An increase in the number of isotopic ratio studies and the vulnerability of some species have led to increased use of non‐lethal methodologies for conservation purposes. In the present work we have compared the δ13C and δ15N isotopic signals of muscle and scales of three different fish species in order to test fish‐scale sampling as a non‐lethal technique in fish trophodynamics. A positive correlation was found between muscle and scales in Argyrosomus regius and Xyrichtys novacula, while Dentex dentex showed no correlation due to the small length range of this species. The isotopic offset (Δ13C and Δ15N) between muscle and scales was significantly different among species (analysis of variance (ANOVA), p < 0.001) with Tukey's post‐hoc HSD indicating a tissue offset difference (p < 0.001) for both stable isotopes in all species, except for Δ13C between A. regius and X. novacula and for Δ15N between D. dentex and X. novacula (p > 0.05). Mean δ13C and δ15N values between species showed significant differences (paired t‐test, p < 0.01) between muscle and scale with an enrichment for δ13C and a depletion for δ15N. Spatial differences were found in the Δ13C of X. novacula between the studied locations, while no differences were found for Δ15N, indicating that non‐geographical differences should be considered in the application of scales instead of muscle for 15N, while for 13C differences in the geographical isotopic offset should be considered. Copyright © 2009 John Wiley & Sons, Ltd.
Electrospray ionisation with selected reaction monitoring for the determination of Mn‐citrate, Fe‐citrate, Cu‐citrate and Zn‐citrate
Authors: Nischwitz Volker , Michalke Bernhard 
Published: July 2009

AbstractCitrate complexes of Mn and Fe, and potentially those of Cu and Zn, are considered as important low molecular mass species in human serum and cerebrospinal fluid (CSF). For example, Mn is supposed to enter the brain under excess exposure as Mn‐citrate leading to neurotoxic effects. Mn‐citrate has been characterised in human CSF using chromatography and electrophoresis online with inductively coupled plasma mass spectrometry, but not yet with molecular mass spectrometry. Therefore, this study explores the potential of electrospray ionisation (ESI) with selected reaction monitoring (SRM) for the detection of metal‐citrate complexes, in particular Mn‐citrate. The collision‐induced dissociation of precursor ions with various metal:citrate stoichiometries was studied for Mn‐citrate, Fe‐citrate, Cu‐citrate and Zn‐citrate. High selectivity was achieved for Mn(II)‐citrate even in respect to Fe(III)‐citrate which forms isobaric precursor ions. The limit of detection for Mn‐citrate was estimated to be around 250 µg L−1 (referring to the total Mn content in the standard) using flow injection. The sensitivity was sufficient for the determination of Mn‐citrate in standard solutions and in an extract of an Mn‐citrate‐containing supplement. An improved ESI source design is expected to reduce the limits of detection significantly. The developed ESI‐SRM method has the potential to provide complementary data for the quality control of current separation methods for metal citrates using element‐selective detection, with application to biomedical samples and further matrices. Copyright © 2009 John Wiley & Sons, Ltd.
Analysing the isotopic life history of the alpine ungulates Capra ibex and Rupicapra rupicapra rupicapra through their horns
Authors: Barbosa Inês C. R. , Kley Maximiliane , Schäufele Rudi , Auerswald Karl , Schröder Wolf , Filli Flurin , Hertwig Stefan , Schnyder Hans 
Published: July 2009

AbstractThe horn of ungulate grazers offers a valuable isotopic record of their diet and environment. However, there have been no reports of the spatio‐temporal variation of the isotopic composition of horns. We investigated patterns of carbon (δ13C) and nitrogen (δ15N) isotopic composition along and perpendicular to the horn axis in Capra ibex and Rupicapra rupicapra rupicapra to assess the effects of animal age, within‐year (seasonal) and inter‐annual variation, natural contamination and sampling position on horn isotope composition. Horns of male C. ibex (n = 23) and R. r. rupicapra (n = 1) were sampled longitudinally on the front (only R. r. rupicapra) and back side and on the surface and sub‐surface. The sides of the R. r. rupicapra horn did not differ in δ13C. In both species, the horn surface had a 0.15‰ lower δ13C and a higher carbon‐to‐nitrogen (C/N) ratio than the sub‐surface. Washing the horn with water and organic solvents removed material that caused these differences. With age, the δ15N of C. ibex horns increased (+0.1‰ year−1), C/N ratio increased, and 13C discrimination relative to atmospheric CO2 (13Δ) increased slightly (+0.03‰ year−1). Geostatistical analysis of one C. ibex horn revealed systematic patterns of inter‐annual and seasonal 13C changes, but 15N changed only seasonally. The work demonstrates that isotopic signals in horns are influenced by natural contamination (δ13C), age effects (13Δ and δ15N), and seasonal (δ13C and δ15N) and inter‐annual variation (δ13C). The methods presented allow us to distinguish between these effects and thus allow the use of horns as isotopic archives of the ecology of these species and their habitat. Copyright © 2009 John Wiley & Sons, Ltd.
Comparison of inert supports in laser desorption/ionization mass spectrometry of peptides: pencil lead, porous silica gel, DIOS‐chip and NALDI™ target
Authors: Shenar Nawar , Cantel Sonia , Martinez Jean , Enjalbal Christine 
Published: July 2009

AbstractIn the search for alternative inert surfaces replacing silicon chips in Desorption/Ionization On porous Silicon (DIOS)‐like mass spectrometry analyses, nanostructured silicon‐based NALDI™ chips were evaluated in Laser Desorption/Ionization (LDI) of peptides. Comparisons were made using commercially available DIOS chips (MassPREP™‐DIOS‐target™), amorphous carbon powder from lead pencil and porous silica gel used for chromatographic purposes as reference supports. A set of synthetic model peptides presenting variable amino acid sequences of various lengths was analyzed under all conditions. The LDI responses of the four ‘matrix‐free’ techniques were compared, especially in terms of peptide detection sensitivity and overall experiment robustness. Copyright © 2009 John Wiley & Sons, Ltd.
In with the old, in with the new: capabilities, strategies, and performance among the Hollywood studios
Authors: Shamsie Jamal , Martin Xavier , Miller Danny 
Published: July 2009

AbstractAn increased focus on turbulent environments has led to a growing interest among researchers in the concept of dynamic capabilities. In this study, we approach dynamic capabilities in a framework of two complementary processes. On one hand, firms can build upon existing capabilities in products and markets in which they have experienced recent success; on the other hand, they can also intentionally focus on other products and markets in which they seek to build capabilities to address their lack of recent success. We examine these two processes within project‐based industries and identify replication and renewal as two types of strategies that firms use to add a dynamic component to their capabilities. We also theorize that the success of each of these strategies is tied to differentiation from rivals, and to firm‐level resource availability and industry‐level demand characteristics. We test these propositions by focusing on the film genres that were offered by the Hollywood studios over a thirty‐year period. Copyright © 2009 John Wiley & Sons, Ltd.
Reputations for toughness in patent enforcement: implications for knowledge spillovers via inventor mobility
Authors: Agarwal Rajshree , Ganco Martin , Ziedonis Rosemarie H. 
Published: July 2009

Abstract‘Job hopping’ by engineers and scientists is widely heralded as an important channel for knowledge spillovers within industries. Far less is known, however, about the actions firms take to reduce the outward flow of knowledge through markets for skilled labor. This study investigates the efficacy of a lever that has received little research attention: corporate reputations for toughness in patent enforcement. Drawing on unique data on enforcement activity, intra‐industry inventor mobility, and patent citations in the U.S. semiconductor industry, we find that a firm's litigiousness significantly reduces spillovers otherwise anticipated from departures of employee inventors, particularly when the hiring organizations are entrepreneurial ventures. Surprisingly, the deterrent effects of patent enforcement are similar in magnitude for firms located in California, a state characterized by open norms for knowledge trading, and firms headquartered in other U.S. states. The study sheds new light on the strategic actions firms use to prevent rivals from capturing value from their investments in human capital and research and development. Copyright © 2009 John Wiley & Sons, Ltd.
Supporting valid interpretations of learning progression level diagnoses
Authors: Steedle Jeffrey T. , Shavelson Richard J. 
Published: July 2009

AbstractAssessments associated with learning progressions are designed to provide diagnostic information about the level and nature of student understanding. Valid interpretations of such diagnoses are only possible when students consistently express the ideas associated with a single learning progression level. Latent class analysis was employed to evaluate whether patterns of expected responses to diagnostic multiple‐choice items afforded valid interpretations of learning progression level diagnoses. Results indicated that students with scientifically accurate understanding of the forces acting on an object with constant speed usually reasoned systematically across items, but many other students did not. Consequently, interpretations of learning progression level diagnoses on a proposed learning progression would often be invalid. Analyses of this sort would be useful in developing and validating future learning progressions. © 2009 Wiley Periodicals, Inc. J Res Sci Teach 46: 699–715, 2009
Experimental mathematics and computational statistics
Authors: Bailey David H. , Borwein Jonathan M. 
Published: July 2009

AbstractThe field of statistics has long been noted for techniques to detect patterns and regularities in numerical data. In this article, we explore connections between statistics and the emerging field of ‘experimental mathematics’. These include both applications of experimental mathematics in statistics as well as statistical methods applied to computational mathematics. Copyright © 2009 John Wiley & Sons, Inc.This article is categorized under:Applications of Computational Statistics > Computational Mathematics
Statistical and Applied Mathematical Sciences Institute
Authors: Berger James 
Published: July 2009

AbstractThe Statistical and Applied Mathematical Sciences Institute (SAMSI) is a national institute in the USA devoted to forging a synthesis of the statistical sciences and the applied mathematical sciences with disciplinary science to confront the very hardest and most important data and model‐driven scientific challenges. The vision of SAMSI is described herein, as well as the research programs that have been undertaken at SAMSI. Opportunities for becoming involved with SAMSI are also highlighted. Such opportunities exist for senior researchers, new researchers, postdoctoral fellows, graduate students, undergraduate students, and K‐12 teachers. Copyright © 2009 John Wiley & Sons, Inc.This article is categorized under:

Applications of Computational Statistics > Organizations and Publications
Ridge regression
Authors: McDonald Gary C. 
Published: July 2009

AbstractRidge regression is a popular parameter estimation method used to address the collinearity problem frequently arising in multiple linear regression. The formulation of the ridge methodology is reviewed and properties of the ridge estimates capsulated. In particular, four rationales leading to a regression estimator of the ridge form are summarized. Algebraic properties of the ridge regression coefficients are given, which elucidate the behavior of a ridge trace for small values of the ridge parameter (i.e., close to the least squares solution) and for large values of the ridge parameter. Further properties involving coefficient sign changes and rates‐of‐change, as functions of the ridge parameter, are given for specific correlation structures among the independent variables. These results help relate the visual behavior of a ridge trace to the underlying structure of the data. Copyright © 2009 John Wiley & Sons, Inc.This article is categorized under:Statistical Models > Linear ModelsAlgorithms and Computational Methods > Least Squares
Algorithms for response adaptive sampling designs
Authors: Hardwick Janis , Stout Quentin F. 
Published: July 2009

AbstractAn experimental design is a formula or algorithm that specifies how resources are to be utilized throughout a study. The design is considered to be good or even optimal if it allows for sufficiently precise and accurate data analysis with the least output of resources such as time, money and experimental units. Most experimental designs use fixed sampling procedures in which the sample sizes and order of allocations to different study groups are known in advance. Copyright © 2009 John Wiley & Sons, Inc.This article is categorized under:

Statistical and Graphical Methods of Data Analysis > Sampling
Detection of outliers
Authors: Hadi Ali S. , Imon A. H. M. Rahmatullah , Werner Mark 
Published: July 2009

AbstractWe present an overview of the major developments in the area of detection of outliers. These include projection pursuit approaches as well as Mahalanobis distance‐based procedures. We also discuss principal component‐based methods, since these are most applicable to the large datasets that have become more prevalent in recent years. The major algorithms within each category are briefly discussed, together with current challenges and possible directions of future research. Copyright © 2009 John Wiley & Sons, Inc.This article is categorized under:Statistical and Graphical Methods of Data Analysis > Robust Methods
Ischemic Preconditioning Confers Antiapoptotic Protection During Major Hepatectomies Performed Under Combined Inflow and Outflow Exclusion of the Liver. A Randomized Clinical Trial
Authors: Arkadopoulos Nikolaos , Kostopanagiotou Georgia , Theodoraki Kassiani , Farantos Charalambos , Theodosopoulos Theodosios , Stafyla Vaia , Vassiliou John , Voros Dionyssios , Pafiti Agathi , Smyrniotis Vassilios 
Published: July 2009

AbstractBackgroundExtensive experimental studies and a few clinical series have shown that ischemic preconditioning (IPC) attenuates oxidative ischemia/reperfusion (I/R) injuries in liver resections performed under inflow vascular control. Selective hepatic vascular exclusion (SHVE) employed during hepatectomies completely deprives the liver of blood flow, as it entails simultaneous clamping of the portal triad and the main hepatic veins. The aim of the present study was to identify whether IPC can also protect hepatocytes during liver resections performed under SHVE.MethodsPatients undergoing major liver resection were randomly assigned to have either only SHVE (control group, n = 43) or SHVE combined with IPC—10 min of ischemia followed by 15 min of reperfusion before SHVE was applied (IPC group, n = 41).ResultsThe two groups were comparable with regard to age, liver resection volume, blood loss and transfusions, warm ischemic time, and total operative time. In liver remnant biopsies obtained 60 min post‐reperfusion, IPC patients had significantly fewer cells stained positive by TUNEL compared to controls (19% ± 8% versus 45% ± 12%; p < 0.05). Also IPC patients had attenuated hepatocyte necrosis, systemic inflammatory response, and oxidative stress as manifested by lower postoperative peak values of aspartate transaminase, interleukin‐6, interleukin‐8, and malondialdehyde compared to controls. Morbidity was similar for the two groups, as were duration of intensive care unit stay and extent of total hospital stay.ConclusionsIn major hepatectomies performed under SHVE, ischemic preconditioning appears to attenuate apoptotic response of the liver remnant, possibly through alteration of inflammatory and oxidative pathways.
Metastasis‐Associated Protein 1 (MTA1) Overexpression is Closely Associated with Shorter Disease‐Free Interval After Complete Resection of Histologically Node‐Negative Esophageal Cancer
Authors: Li Shu‐Hai , Wang Zhou , Liu Xiang‐Yan 
Published: July 2009

AbstractBackgroundThe purpose of the present study was to investigate the expression of metastasis‐associated protein 1 (MTA1) and its relationship to the disease‐free interval after resection of pathologic N0 (pN0) esophageal squamous cell cancer (ESCC).MethodsThe subjects were 90 patients who successfully underwent complete resection of pN0 ESCC between May 2001 and May 2003. Immunohistochemical staining for MTA1 protein was performed using the avidin–biotin peroxidase complex method. Log‐rank test was performed to compare the disease‐free interval, and Cox regression multivariate analysis was performed to judge independent prognostic factors.ResultsMetastasis‐associated protein 1 overexpression was detected in 40 esophageal cancer tissues. Disease‐free interval was significantly associated with MTA1 protein overexpression (p = 0.015). The overall 5‐year survival rate was 45.6%, the 5‐year survival rate of patients with MTA1 protein overexpression was significantly lower than that of those without overexpression (25.0 versus 62.0%; p < 0.001). The results of multivariate analysis confirmed that T status and MTA1 protein overexpression were independent prognostic factors.ConclusionsMetastasis‐associated protein 1 overexpression was detected in pN0 ESCC and was significantly correlated with shorter disease‐free interval. T status and MTA1 protein overexpression were both independent prognostic factors. These findings suggested MTA1 might be a predictor of relapsing phenotype and a prognostic factor in esophageal cancer.