bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tracking the weathering of basalts on Mars using lithium isotope fractionation models
Authors: Fairén Alberto G. , Losa‐Adams Elisabeth , Gil‐Lozano Carolina , Gago‐Duport Luis , Uceda Esther R. , Squyres Steven W. , Rodríguez J. Alexis P. , Davila Alfonso F. , McKay Christopher P. 
Published: March 2015

AbstractLithium (Li), the lightest of the alkali elements, has geochemical properties that include high aqueous solubility (Li is the most fluid mobile element) and high relative abundance in basalt‐forming minerals (values ranking between 0.2 and 12 ppm). Li isotopes are particularly subject to fractionation because the two stable isotopes of lithium—7Li and 6Li—have a large relative mass difference (∼15%) that results in significant fractionation between water and solid phases. The extent of Li isotope fractionation during aqueous alteration of basalt depends on the dissolution rate of primary minerals—the source of Li—and on the precipitation kinetics, leading to formation of secondary phases. Consequently, a detailed analysis of Li isotopic ratios in both solution and secondary mineral lattices could provide clues about past Martian weathering conditions, including weathering extent, temperature, pH, supersaturation, and evaporation rate of the initial solutions in contact with basalt rocks. In this paper, we discuss ways in which Martian aqueous processes could have lead to Li isotope fractionation. We show that Li isotopic data obtained by future exploration of Mars could be relevant to highlighting different processes of Li isotopic fractionation in the past, and therefore to understanding basalt weathering and environmental conditions early in the planet's history.
Statistical Analysis ofDNAMicroarray Data
Authors: Datta Susmita , Gill Ryan 
Published: March 2015

AbstractNot too long ago, geneticists dealt with only one or two genes simultaneously. Microarray technology is the first of its kind by which scientists were able to study the expressions of thousands of genes in a single experiment. However, owing to its novelty and its capability of measuring such a large volume of information, it has gone through several stages of perfection at every stage of data analysis starting from data normalization to gene annotation. Statisticians and computational biologists made significant contributions toward these. Earlier, we have provided a very brief summary of some of the important statistical work in the field.
Graphical Displays
Authors: Martin Michael A. , Welsh A. H. 
Published: March 2015

AbstractGraphical methods are fundamental tools of modern data analysis. Graphics are useful for communicating complex information quickly and easily, and are thus excellent tools for describing data and for providing direction in data analysis. They are essential tools for building statistical models from data, and for assessing model adequacy. This article surveys the use of statistical graphics in describing data and for statistical modeling, including models for relating variables, spatiotemporal dependence, and survival data. Graphics are also critical tools for visualizing and analyzing high‐dimensional data. The article illustrates the use of graphics in statistical modeling through numerous examples drawn from the life sciences.
Optimization and Nonlinear Equations
Authors: Smyth Gordon K. 
Published: March 2015

Abstract
Optimization means finding the argument that minimizes or maximizes a given function such as a likelihood function or a sum of squares. Many optimization algorithms are derived from algorithms that solve the nonlinear equations defined by setting the derivative of the objective function equal to zero. This article discusses a number of methods for unconstrained optimization, including bisection and golden search in the univariate case and Newton's method and quasi‐Newton algorithms in the multivariate case. Applications to maximum likelihood estimation, Fisher's method of scoring, nonlinear regression, and generalized linear models are described. Restricted step modifications are discussed for preventing divergence of Newton‐type algorithms. A number of derivative‐free methods are discussed, including the Nelder–Mead simplex method, methods with numeric derivatives, conjugate methods, and the EM algorithm.
Teaching Statistics to Psychologists in an Online World
Authors: Spilich George 
Published: March 2015

AbstractThis is an exciting time for those who teach statistics to undergraduate and graduate students in the behavioral sciences. This article traces the course of five revolutions in how we teach statistics, starting with the introduction of mechanical calculators, continuing through the development of statistical packages, and culminating in the creation of online content that a student can access at any time or in any place. The author concludes by proposing that digital editing and drawing applications that are free or low cost create the promise of democratizing the dissemination of content by allowing every instructor to become a content provider.
Sibling Interaction Effects
Authors: Boomsma Dorret I. 
Published: March 2015

Abstract

Children often grow up in the company of siblings, with whom they are genetically related. In this situation, the behavior of one sibling may influence the behavior of the other sibling. Assuming the heritability of the behavior of interest is greater than zero, such sibling interaction will render the “environment” of one child predictable from the genotypes of his or her siblings. In cross‐sectional data, detection of sibling interactions is based on the comparison of variances and covariances of siblings reared in different densities (e.g., twins and singletons) or of siblings of different degrees of genetic relatedness (e.g., mono‐ and dizygotic twins). For instance, in the classical
twin design
, a difference in phenotypic variance between mono‐ and dizygotic twins and a pattern of twin correlations, inconsistent with additive genetic influences, are indicative of sibling interaction. In longitudinal designs, sibling interactions can be modeled by means of phenotype to environment transmission, where the phenotype of one sibling at time
t
influences the environment of the second sibling at
t
+ 1.
Joint Action Models
Authors: Piegorsch Walter W. 
Published: March 2015

AbstractOne of the simplest forms of data is the dichotomous indication of whether or not a specific event occurs, categorized as “responses” and “nonresponses,” respectively. In some settings, there may be two classification schemes or qualitative factorizations examined for their mutual effect on the response. Alternatively, the differential response of two or more populations with respect to a single classification variable may be of interest. This article presents some basic models and methods for assessing the joint action in such dual‐factor studies with dichotomous data.
Stochastic Simulation of Rare Events
Authors: Gatto Riccardo 
Published: March 2015

AbstractStochastic simulation is an important and practical technique for computing probabilities of rare events, like the payoff probability of a financial option, the probability that a queue exceeds a certain level, or the probability of ruin of the insurer's risk process. Rare events occur so infrequently, that they cannot be reasonably recorded during a standard simulation procedure: specific simulation algorithms that thwart the rarity of the event to simulate are required. An important algorithm in this context is based on changing the sampling distribution and it is calledimportance sampling. Optimal Monte Carlo algorithms for computing rare event probabilities are either logarithmic efficient or possess bounded relative error.
Fabrication of antibacterial silver nanoparticle‐modified chitosan fibers using Eucalyptus extract as a reducing agent
Authors: Arvand Mansoor , Mirzaei Esmaeil , Derakhshan Mohammad Ali , Kharrazi Sharmin , Sadroddiny Esmaeil , Babapour Mahmoud , Faridi‐Majidi Reza 
Published: March 2015

ABSTRACTGreen chemical method could be a promising route to achieve large scale synthesis of nanostructures for biomedical applications. Here, we describe a green chemical synthesis of silver nanoparticles (Ag NPs) on chitosan‐based electrospun nanofibers using Eucalyptus leaf extract. A series of silver salt (AgNO3) amounts were added to a certain composition of chitosan/polyethylene oxide aqueous acetic acid solution. The solutions were then electrospun to obtain nanofibrous mats and then, morphology and size of nanofibers were analyzed by scanning electron microscopy (SEM). Incubation of AgNO3‐containing mats into Eucalyptus leaf extract led to the formation of Ag NP clusters with average diameter of 91 ± 24 nm, depicted by SEM and transmission electron microscopy. Surface enhanced Raman spectroscopy also confirmed formation of Ag NPs on the nanofibers. The mats also showed antimicrobial activity against Escherichia coli and Staphylococcus aureus bacteria with bigger inhibition zone for extract‐exposed mats against S. aureus. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42133.
Evaluation of the efficiency of copolymers of methyl methacrylate and vinyl acetate synthesized by emulsion polymerization for control of aqueous filtrate loss
Authors: Nunes Rita de Cassia P. , Pires Renata V. , Lucas Elizabete F. 
Published: March 2015

ABSTRACTOne of the main problems faced while drilling oil wells is loss of fluid to the rock formation. This loss can be reduced with the use of chemical additives called filtrate controllers, which must be tailored to the specific characteristics of the rock formation and drilling conditions. In this study, copolymers made of methyl methacrylate‐co‐vinyl acetate were synthesized by the emulsion polymerization technique, the most efficient technique to obtain copolymers with widely differing reactivity ratios. The products were characterized and evaluated for filtrate reduction efficiency, in the form of an emulsion and a polymer suspended in water. The filtrate reduction percentage, on the order of 80%, increased with higher concentration of vinyl acetate. The use of the polymer suspended in water caused only a slightly greater reduction in filtrate loss than that produced by the respective emulsion. However, other important advantages are associated with the suspended formulation: lower optimal concentration (∼ 8.5 g/mL), formation of extremely discrete filter cake particles and better logistical aspects, since in the case of emulsions, the volume of material that must be transported is much greater. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42191.
Microwave‐assisted chemical synthesis of conducting polyindole: Study of electrical property using Schottky junction
Authors: Tiwari Madhu , Kumar Ashish , Umre Harshit Sunil , Prakash Rajiv 
Published: March 2015

ABSTRACTA facile and rapid enhanced microwave‐assisted route for one‐pot synthesis has been developed to polymerize indole moiety using two different oxidizing agents for 60 s exposure at 30 ± 1°C. As‐synthesized conducting polyindoles, obtained by varying the synthesis process and oxidant, have been well characterized by various techniques. UV–vis, FT‐IR, and NMR have been used for their structural analysis while gel permeation chromatography, thermogravimetric analysis, and conductivity measurement to evaluate their enhanced properties and to perform a comparative study. Morphological texture of polyindole synthesized via different techniques has studied by scanning electron microscopy analysis. PIn synthesized by KIO3 (microwave synthesis) exhibit interconnecting texture which may be due to high level of supersaturation of solution under the influence of microwave irradiation. Thereafter, electrical property of spin‐coated thin film of polyindole is examined using four probe method and Al metal/semiconducting material Schottky junction. Microwave‐assisted polymer shows better performance for Schottky devices due to difference in charge transport, morphological texture, and distribution of Mn. The PIn synthesized via microwave irradiation with better charge transport across the metal/polymer interfaces shows the potential of this technique for synthesis of such polymers with enhanced electronic properties. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42192.
Sustainability Targets in Executive Remuneration: Targets, Time Frame, Country and Sector Specification
Authors: Maas Karen , Rosendaal Sanne 
Published: March 2015

AbstractExisting remuneration plans for CEOs still mainly focus on financial performance and do not necessarily promote sustainable value creation for their firms. By way of reaction to this, a growing number of academics and practitioners are acknowledging the need for the inclusion of sustainability targets in executive remuneration. This study examines the current status of the use of sustainability targets in executive remuneration specified by country, sector and targets. Based on a sample of 490 listed firms from 11 countries and different sectors, the use of targets related to sustainability in executive remuneration is assessed. The targets are specified by kind of target (short term and long term) and content of target (environmental, social or a combination of both). The results of this study show that (a) in 2010 on average 33% of the firms used sustainability targets in remuneration, (b) mainly the ‘dirty’ industries use targets, (c) the targets used are mainly short‐term targets and (d) they focus on social issues. Copyright © 2015 John Wiley & Sons, Ltd and ERP Environment
Synthesis of a Fluorine‐Containing Cis‐Cisoidal One‐Handed Helical Polyphenylacetylene and Application of Highly Selective Photocyclic Aromatization Product on Oxygen Permselective Membrane
Authors: Zang Yu , Yin Guanwu , Aoki Toshiki , Teraguchi Masahiro , Kaneko Takashi , Ma Liqun , Jia Hongge 
Published: March 2015

AbstractA novel phenylacetylene monomer having a perfluorinated alkyl group (M-F) was synthesized and polymerized in a chiral catalytic system to yield a one‐handed helical polymer. The ability and efficiency of the chiral induction of the fluorine‐containing monomer in the helix‐sense‐selective polymerization (HSSP) was much higher than those of a monomer having the corresponding alkyl group (M-H) we reported before. The resulting polymer P-F showed cis‐cisoidal one‐handed helical conformation, and was suitable for highly selective photocyclic aromatization (SCAT) to give a 2D surface modifier (T-F). Oxygen permselectivity through a base polymer membrane was highly enhanced from 1.83 to 2.36 by adding a small amount (1–5 wt%) of the 2D surface modifier T-F. The improvement was thought to be caused by improvement of solution selectivity on the membrane surface which the 2D surface modifier effectively covered. Chirality 27:459–463, 2015. © 2015 Wiley Periodicals, Inc.
T1ρ imaging in premanifest Huntington disease reveals changes associated with disease progression
Authors: Wassef Shafik N. , Wemmie John , Johnson Casey P. , Johnson Hans , Paulsen Jane S. , Long Jeffrey D. , Magnotta Vincent A. 
Published: March 2015

AbstractBackgroundImaging biomarkers sensitive to Huntington's disease (HD) during the premanifest phase preceding motor diagnosis may accelerate identification and evaluation of potential therapies. For this purpose, quantitative MRI sensitive to tissue microstructure and metabolism may hold great potential. We investigated the potential value of T1ρ relaxation to detect pathological changes in premanifest HD (preHD) relative to other quantitative relaxation parameters.MethodsQuantitative MR parametric mapping was used to assess differences between 50 preHD subjects and 26 age‐ and sex‐matched controls. Subjects with preHD were classified into two progression groups based on their CAG‐age product (CAP) score; a high and a low/moderate CAP group. Voxel‐wise and region‐of‐interest analyses were used to assess changes in the quantitative relaxation times.ResultsT1ρ showed a significant increase in the relaxation times in the high‐CAP group, as compared to controls, largely in the striatum. The T1ρ changes in the preHD subjects showed a significant relationship with CAP score. No significant changes in T2 or T2* relaxation times were found in the striatum. T2* relaxation changes were found in the globus pallidus, but no significant changes with disease progression were found.ConclusionThese data suggest that quantitative T1ρ mapping may provide a useful marker for assessing disease progression in HD. The absence of T2 changes suggests that the T1ρ abnormalities are unlikely owing to altered water content or tissue structure. The established sensitivity of T1ρ to pH and glucose suggests that these factors are altered in HD perhaps owing to abnormal mitochondrial function. © 2015 International Parkinson and Movement Disorder Society
Coil combination for receive array spectroscopy: Are data‐driven methods superior to methods using computed field maps?
Authors: Rodgers Christopher T. , Robson Matthew D. 
Published: March 2015

PurposeCombining spectra from receive arrays, particularly X‐nuclear spectra with low signal‐to‐noise ratios (SNRs), is challenging. We test whether data‐driven combination methods are better than using computed coil sensitivities.TheorySeveral combination algorithms are recast into the notation of Roemer's classic formula, showing that they differ primarily in their estimation of coil receive sensitivities. This viewpoint reveals two extensions of the whitened singular‐value decomposition (WSVD) algorithm, using temporal or temporal + spatial apodization to improve the coil sensitivities, and thus the combined spectral SNR.MethodsRadiofrequency fields from an array were simulated and used to make synthetic spectra. These were combined with 10 algorithms. The combined spectra were then assessed in terms of their SNR. Validation used phantoms and cardiac 31P spectra from five subjects at 3T.ResultsCombined spectral SNRs from simulations, phantoms, and humans showed the same trends. In phantoms, the combined SNR using computed coil sensitivities was lower than with WSVD combination whenever the WSVD SNR was >14 (or >11 with temporal apodization, or >9 with temporal + spatial apodization). These new apodized WSVD methods gave higher SNRs than other data‐driven methods.ConclusionIn the human torso, at frequencies ≥49 MHz, data‐driven combination is preferable to using computed coil sensitivities. Magn Reson, 2015. © 2015 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 License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. Magn Reson Med 75:473–487, 2016. © 2015 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine.
Synthesis of polyacrylonitrile mediated by manganese(III) acetylacetonate (Mn(acac)3) and 2‐cyanoprop‐2‐yl dithionaphthalenoate
Authors: Xu Yuanyuan , Sun Jinming , Chen Hou , Bai Liangjiu , Tao Qian , Yu Lili , Wang Yating 
Published: March 2015

ABSTRACT2‐Cyanoprop‐2‐yl dithionaphthalenoate (CPDN) was successfully used as the chain transfer agent to prepare polyacrylonitrile in combination with manganese(III) acetylacetonate (Mn(acac)3) as the initiator. The novel polymerization exhibited well “living”/controlled characteristics. The polymerization behavior was revealed to comply with features of reversible addition–fragmentation chain transfer polymerization process. Mn(acac)3 played a key role as the initiator rather than the radical trapping agent in polymerization and exhibited better control performance than azo‐initiator. The narrowest molecular weight distribution was 1.31 under the condition of [AN]0:[Mn(acac)3]0:[CPDN]0 = 200:1:0.025 and AN:DMF = 1:1 (V/V). Various feed ratios of Mn(acac)3 and CPDN were also investigated in detail. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 1305–1309
Synthesis, characterization, and photovoltaic properties of dithienylbenzobisazole‐dithienylsilole copolymers
Authors: Bhuwalka Achala , Ewan Monique D. , Mike Jared F. , Elshobaki Moneim , Kobilka Brandon , Chaudhary Sumit , Jeffries‐EL Malika 
Published: March 2015

ABSTRACTThree conjugated polymers comprised of dioctyl‐dithieno‐[2,3‐b:2',3'‐d]silole and a donor‐acceptor‐donor triad of either cis‐benzbisoxazole, trans‐benzobisoxazole or trans‐benzobisthiazole were synthesized via the Stille cross‐coupling reaction. The impact of varying the heteroatoms and/or the location within the benzobisazole moiety on the optical and electronic properties of the resulting polymers was evaluated via cyclic voltammetry and UV‐Visible spectroscopy. All of the polymers have similar optical band‐gaps of ∼1.9 eV and highest occupied molecular orbital levels of −5.2 eV. However, the lowest unoccupied molecular orbitals (LUMO) ranged from −3.0 to −3.2 eV. Interestingly, when the polymers were used as donor materials in bulk‐heterojunction photovoltaic cells with PC71BM as the electron‐acceptor, the benzobisoxazole‐based polymers gave slightly better results than the benzobisthiazole‐containing polymers with power conversion efficiencies up to 3.5%. These results indicate that benzobisoxazoles are promising materials for use in OPVs. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 1533–1540
Habitat Suitability Criteria via Parametric Distributions: Estimation, Model Selection and Uncertainty
Authors: Som Nicholas A. , Goodman Damon H. , Perry Russell W. , Hardy Thomas B. 
Published: March 2015

AbstractPrevious methods for constructing univariate habitat suitability criteria (HSC) curves have ranged from professional judgement to kernel‐smoothed density functions or combinations thereof. We present a new method of generating HSC curves that applies probability density functions as the mathematical representation of the curves. Compared with previous approaches, benefits of our method include (1) estimation of probability density function parameters directly from raw data, (2) quantitative methods for selecting among several candidate probability density functions, and (3) concise methods for expressing estimation uncertainty in the HSC curves. We demonstrate our method with a thorough example using data collected on the depth of water used by juvenile Chinook salmon (Oncorhynchus tschawytscha) in the Klamath River of northern California and southern Oregon. All R code needed to implement our example is provided in the appendix. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.