bluuebunny/crossref_metadata_2025_split huggingface dataset:
Computing Wrench Cones for Planar Rigid Body Contact Tasks
Authors: Balkcom Devin J. , Trinkle J.C. 
Published: July 2003

The contribution of this paper is the expansion of the range of possibilities in the analysis, planning, and control of contact tasks. The successful execution of any contact task fundamentally requires the application of wrenches (forces and moments) consistent with the task. We develop an algorithm for computing the entire set of external wrenches consistent with achieving a given augmented contact mode (e.g., sliding at contact 1, rolling at contact 2, and approaching potential contact 3) for one fixed and one moving part in the plane. Unfortunately, because of the problem of frictional indeterminacy, it is usually not enough to determine the set of wrenches consistent with achieving a contact mode. Some of the computed wrenches may also be consistent with other undesirable contact modes. However, set operations on the cones returned by our algorithm can be designed to find the wrenches consistent only with desired contact modes. In this paper we also present some applications of the algorithm to analysis and planning problems. We show how to use set operations to compute the set of external wrenches with respect to which a fixtured part is `strongly stable'. If the applied external wrench is in this set, the part is guaranteed not to move. We also show how the algorithm may be used to create sensorless plans that guarantee that a workpiece will be correctly inserted into a fixture.
Dynamic Sensor Planning and Control for Optimally Tracking Targets
Authors: Spletzer John R. , Taylor Camillo J. 
Published: July 2003

In this paper, we present an approach to the problem of actively controlling the configuration of a team of mobile agents equipped with cameras so as to optimize the quality of the estimates derived from their measurements. The issue of optimizing the robots' configuration is particularly important in the context of teams equipped with vision sensors, since most estimation schemes of interest will involve some form of triangulation. We provide a theoretical framework for tackling the sensor planning problem, and a practical computational strategy inspired by work on particle filtering for implementing the approach. We then extend our framework by showing how modeled system dynamics and configuration space obstacles can be handled. These ideas have been applied to a target tracking task, and demonstrated both in simulation and with actual robot platforms. The results indicate that the framework is able to solve fairly difficult sensor planning problems online without requiring excessive amounts of computational resources.
Comparison of the environmental damage caused by vehicles with different alternative fuels and drivetrains in a Brussels context
Authors: Van Mierlo J , Vereecken L , Maggetto G , Favrel V , Meyer S , Hecq W 
Published: July 2003

A comprehensive methodology has been developed to compare the environmental damage caused by vehicles with different alternative fuels, such as CNG, LPG, etc., and drivetrains, such as electric and hybrid drives. This paper describes how the environmental effect of vehicles should be defined and includes parameters concerning vehicle emissions and their influence on human wellbeing and the environment. It then describes how the environmental effect of vehicles could be defined, taking into account the availability of accurate and reliable data. Rating systems are analysed as a means of comparing the environmental effect of vehicles, allowing decision-makers to dedicate their financial and non-financial policies and measures as a function of the ecological damage. Different types of pollution (acid rain, photochemical air pollution, noise pollution, etc.) and their effect on numerous receptors such as ecosystems, buildings and human beings (e.g. cancer, respiratory diseases, etc.) and global warming are considered. The methodology described, known as Ecoscore, is based on a methodology similar to life cycle assessment (LCA) which considers the part played by emissions in certain types of damage (e.g. by using the exposure-response damage function). Total emissions involve oil extraction, transport and refinery, fuel distribution and electricity generation and distribution (well-to-wheel approach). Emissions due to the production, use and dismantling of the vehicle (cradle-to-grave approach) should also be considered. The different types of damage are normalized to make comparisons possible. Hence, a reference value (determined by a chosen reference vehicle) will be defined as a target value (the normalized value will thus measure a kind of distance to target). The contribution of the different normalized types of damage to a single value—Ecoscore—is based on a panel weighting method. This new approach differs from other methodologies in that it has been especially developed for the assessment of the environmental effect of vehicle emissions in an urban context, such as the Brussels Capital Region. Additionally, this methodology not only considers conventional vehicles but can also evaluate all alternative fuels and drivetrains with new vehicle technologies. Some examples of Ecoscore calculation are illustrated.
Misclassification in Logistic Regression with Discrete Covariates
Authors: Davidov Ori , Faraggi David , Reiser Benjamin 
Published: July 2003

AbstractWe study the effect of misclassification of a binary covariate on the parameters of a logistic regression model. In particular we consider 2 × 2 × 2 tables. We assume that a binary covariate is subject to misclassification that may depend on the observed outcome. This type of misclassification is known as (outcome dependent) differential misclassification. We examine the resulting asymptotic bias on the parameters of the model and derive formulas for the biases and their approximations as a function of the odds and misclassification probabilities. Conditions for unbiased estimation are also discussed. The implications are illustrated numerically using a case control study. For completeness we briefly examine the effect of covariate dependent misclassification of exposures and of outcomes.
Estimation of Sample Size for Reference Interval Studies
Authors: Troendle James F. , Yu Kai F. 
Published: July 2003

AbstractThe currently used criterion for sample size calculation in a reference interval study is not well stated and leads to imprecise control of the ratio in question. We propose a generalization of the criterion used to determine sufficient sample size in reference interval studies. The generalization allows better estimation of the required sample size when the reference interval estimation will be using a power transformation or is nonparametric. Bootstrap methods are presented to estimate sample sizes required by the generalized criterion. Simulation of several distributions both symmetric and positively skewed is presented to compare the sample size estimators. The new method is illustrated on a data set of plasma glucose values from a 50‐g oral glucose tolerance test. It is seen that the sample sizes calculated from the generalized criterion leads to more reliable control of the desired ratio.
Robust Linear Mixed Models with Normal/Independent Distributions and Bayesian MCMC Implementation
Authors: Rosa G.J.M. , Padovani C.R. , Gianola D. 
Published: July 2003

AbstractLinear mixed effects models have been widely used in analysis of data where responses are clustered around some random effects, so it is not reasonable to assume independence between observations in the same cluster. In most biological applications, it is assumed that the distributions of the random effects and of the residuals are Gaussian. This makes inferences vulnerable to the presence of outliers. Here, linear mixed effects models with normal/independent residual distributions for robust inferences are described. Specific distributions examined include univariate and multivariate versions of the Student‐t, the slash and the contaminated normal. A Bayesian framework is adopted and Markov chain Monte Carlo is used to carry out the posterior analysis. The procedures are illustrated using birth weight data on rats in a toxicological experiment. Results from the Gaussian and robust models are contrasted, and it is shown how the implementation can be used for outlier detection. The thick‐tailed distributions provide an appealing robust alternative to the Gaussian process in linear mixed models, and they are easily implemented using data augmentation and MCMC techniques.
Mental health professionals' attitudes towards people who are deaf
Authors: Cooper Alexandra E. , Rose John , Mason Oliver 
Published: July 2003

AbstractMental health professionals' attitudes towards deaf people were examined in relation to their previous contact with deaf people and their knowledge of deafness. Data were gathered regarding different aspects of contact, including the number and type of relationships participants had had with deaf people. A cognitive‐processing theory of attitude change following contact (Rothbart & John, 1985) was explored. Knowledge of deafness did not correlate with attitudes towards deaf people but a relationship was found between the amount of contact that professionals had with deaf people of equal or higher status and more positive attitudes. Copyright © 2003 John Wiley & Sons, Ltd.
‘They were brilliant, I don't know what I would've done if they hadn't been here’: the group concept problem revisited
Authors: Finlay W. M. L. , Rutland A. , Shotton J. 
Published: July 2003

AbstractThis article concerns the group concept problem in people labelled as having learning disabilities, described in a series of papers by Gibbons and colleagues (Gibbons, 1981, 1985a, 1985b; Gibbons & Gibbons, 1980; Gibbons & Kassin, 1982). We argue that the interpretations of these studies are questionable, and alternative explanations for the patterns of results found are possible. Examples from a study in which people with the label talked about particular others who also have the label are presented. In these examples, the category was not represented as homogeneous, relationships with others were valued, and a desire for distance was only found when participants talked about people who behaved aggressively. The findings are discussed with reference to the social model of disability. Copyright © 2003 John Wiley & Sons, Ltd.
Personality, social support and burnout among human service professionals in India
Authors: Brown Nathan C. , Prashantham Baddam J. , Abbott Martin 
Published: July 2003

AbstractRecent research has investigated the relationship between personality and social support in predicting various forms of adjustment. This study explores this relationship in a sample of 137 human service professionals engaged in post‐degree clinical skills training at the Christian Counselling Centre in Vellore, India. The impact of certain forms of social support on burnout was examined, after controlling for the effect of the personality trait of anxiety. As hypothesized, perceived social support was negatively associated with burnout, even after controlling for the effects of anxiety. This pattern was strongest for the males in this sample. Emotional exhaustion and depersonalization were the components of burnout most strongly related to perceived support. The perception of support received from ‘work‐related’ and ‘other’ relationships made a stronger contribution than did ‘family’ or ‘social’ ties with respect to burnout. Implications for future cross‐cultural investigation of the relationships among personality, social support and adjustment are discussed. Copyright © 2003 John Wiley & Sons, Ltd.
CAMP: A community‐based approach to promoting safe sex behaviour in adolescence
Authors: Guzmán Bianca L. , Casad Bettina J. , Schlehofer‐Sutton Michèle M. , Villanueva Christina M. , Feria Aida 
Published: July 2003

AbstractThe primary goal of this study was to describe the development and assessment of the Community Awareness Motivation Partnership (CAMP) Teen Theatre intervention. Based on the behavioural ecological model, CAMP addressed the role of contraceptive use in safe sex behaviour through a brief informative, entertaining, and culturally responsive dramatization programme. Adolescents (N = 1613) between the ages of 11 and 18 (M = 13.31, SD = 0.76) received the intervention, and 961 participants completed both pre‐ and post‐tests. The majority of participants were Latino (78.5%, n =  1039), many of whom were first generation immigrants. Results indicated that the intervention increased participants' reported intentions to delay sex and use contraceptives. The intervention produced short‐term changes in safe‐sex behavioural intentions and knowledge. Suggestions for producing long‐term changes were discussed. Copyright © 2003 John Wiley & Sons, Ltd.
Reinvestigation of the Noncatalyzed Coupling of Aryllithium with Haloarene: A Novel Aromatic Nucleophilic Substitution Pathway
Authors: Becht Jean‐Michel , Gissot Arnaud , Wagner Alain , Mioskowski Charles 
Published: July 2003

AbstractNoncatalyzed coupling reactions of aryllithiums and haloarenes proceed not only through the well‐known aryne route but also, in some cases, through a novel addition–elimination pathway. Indeed, ortho‐chloro‐ and ortho‐bromomethoxyarenes lead selectively to the corresponding ortho‐biaryls through a chelation‐driven aromatic nucleophilic substitution pathway. Contrary to common belief, such noncatalyzed coupling reactions often proceed with high regioselectivity and high yield. These results underline the potency of such simple reactions and open up a straightforward access to a wide range of biaryl structures; this also appears particularly useful for large‐scale and biaryl building‐block syntheses, as only cheap and readily available substrates are involved.
Efficient Photoinduced Conversion of an Azo Dye on Hexachloroplatinate(IV)‐Modified TiO2 Surfaces under Visible Light Irradiation—A Photosensitization Pathway
Authors: Zhao Wei , Chen Chuncheng , Ma Wanhong , Zhao Jincai , Wang Dianxun , Hidaka Hisao , Serpone Nick 
Published: July 2003

AbstractThe titanium dioxide photocatalyst is employed to examine the influence of chemisorbed hexachloroplatinate(IV) anions (PtCl62−) on the surface of P‐25 TiO2 particles on the photoinduced conversion of the azo dye Ethyl Orange (EO) in visible light‐illuminated PtIV/TiO2 dispersions. Spin‐trap electron spin resonance (ESR) spectral results, measurement of quantities of organoperoxides formed, total organic carbon (TOC) and chemical oxygen demand (CODCr) assays, together with XPS evidence show that the self‐sensitized transformation dynamics of the EO dye mediated by PtIV/TiO2 are much faster than those occurring on naked TiO2 under otherwise identical conditions of visible light irradiation. X‐ray photoelectron spectral data also show that under the experimental conditions used, no Pt0 formed on the titania particles during visible light irradiation. We propose a reaction mechanism in which the more rapid conversion of EO in the presence of PtCl62− is caused principally by photoexcitation of the dye and not by localized excitation of the tetrachloroplatinate(IV)/TiO2 particles.
Synthesis and Structure of New Carborane‐Substituted Cyclotriphosphazenes
Authors: Abizanda Domingo , Crespo Olga , Gimeno M. Concepcion , Jiménez Josefina , Laguna Antonio 
Published: July 2003

Abstract The reactions of [N3P3Cl6] with one, two, or three equivalents of the difunctional 1,2‐closo‐carborane C2B10H10{CH2OH}2 and K2CO3 in acetone have been investigated. These reactions led to the new spiro‐closo‐carboranylphosphazenes gem‐[N3P3Cl6−2n{(OCH2)2C2B10H10}n] (n=1 (1), 2 (2)) and the first fully carborane‐substituted phosphazene gem‐[N3P3{(OCH2)2C2B10H10}3] (3). A bridged product, non‐gem‐[N3P3Cl4{(OCH2)2C2B10H10}] (4), was also detected. The reaction of the well‐ known spiro derivatives [N3P3Cl2(O2C12H8)2] and [N3P3Cl4(O2C12H8)] with the same carborane‐diol and K2CO3 in acetone gave the new compounds gem‐[N3P3(O2C12H8)3−n{(OCH2)2C2B10H10}n] (n=1 (5) or 2 (6), respectively), without signs of intra‐ or intermolecularly bridged species. Upon treatment with NEt3 in acetone, compound 5 was converted into the corresponding nido‐carboranylphosphazene. However, the reaction of gem‐[N3P3(O2C12H8)2{(OCH2)2C2B10H10}] (5) with NEt3 in ethanol instead of acetone proceeded in a different manner to give the new compound (NHEt3)2[N3P3(O2C12H8)2(O){OCH2C2B9H10CH2OCH2CH3}] (7). For compounds with two 2,2′‐dioxybiphenyl units, gem‐[N3P3(O2C12H8)2{(OCH2)2C2B10H10}] (5), (NHEt3)[N3P3(O2C12H8)2{(OCH2)2C2B9H10}] (8), and (NHEt3)2[N3P3(O2C12H8)2(O){OCH2C2B9H10CH2OCH2CH3}] (7), a mixture of different stereoisomers may be expected. However, for 5 and 7 only the meso compounds seem to be formed, with the same (R,S)‐configuration as in the precursor [N3P3Cl2(O2C12H8)2]. The reaction of 5 to give 8 seems to proceed with a change of configuration at one phosphorus center, giving a racemic mixture. The crystal structures of the nido‐carboranylphosphazenes 7 and 8 have been confirmed by X‐ray diffraction methods.
Highly Diastereoselective Additions to Polyhydroxylated Pyrrolidine Cyclic Imines: Ready Elaboration of Aza‐Sugar Scaffolds To Create Diverse Carbohydrate‐Processing Enzyme Probes
Authors: Chapman Timothy M. , Courtney Steve , Hay Phil , Davis Benjamin G. 
Published: July 2003

AbstractRepresentative diastereomeric, erythritol and threitol polyhydroxylated pyrrolidine imine scaffolds have been rapidly elaborated to diversely functionalized aza‐sugars through highly diastereoselective organometallic (RM) additions (R=Me, Et, allyl, hexenyl, Ph, Bn, pMeO‐Bn). The yields for these additions have all been substantially enhanced from previously optimised levels (<58 %) for normal additions using a reverse addition procedure (e.g. R=Ph; 44 % normal mode → 78 % reverse mode). The high diastereoselectivities (>98 % de for all except R=Me) are consistent with additions that are controlled by the configuration of the C‐2 centre adjacent to the azomethine imine carbon and the conformation of the pyrrolidine imine. The high potential of this method was demonstrated by concise syntheses of 1‐epi‐ and 2‐epi‐desacetylanisomycins. In addition, the late stage addition of hydrophobic substituents, which this imine addition methodology allows, enabled the preparation of novel aza‐sugars with enhanced inhibitory potential. This was highlighted by the screening of a representative selection of these “hydrophobically‐modified” aza‐sugars against a diverse panel of 12 non‐mammalian and human carbohydrate‐processing enzymes. This identified a novel nanomolar α‐galactosidase inhibitor (IC50=250 nM) and a novel highly selective glucosylceramide synthase inhibitor (IC50=52 μM, no α‐glucosidase inhibition at 1 mM). Furthermore, analysis of the structure–activity relationships of racemic series of inhibitors allowed some validation of Fleet's mirror‐image enzyme active site postulate.
Combined Effects of Electrostatic and π–π Stacking Interactions: Selective Binding of Nucleotides and Aromatic Carboxylates by Platinum(II)–Aromatic Ligand Complexes
Authors: Yajima Tatsuo , Maccarrone Giuseppe , Takani Masako , Contino Annalinda , Arena Giuseppe , Takamido Reiko , Hanaki Mieko , Funahashi Yasuhiro , Odani Akira , Yamauchi Osamu 
Published: July 2003

AbstractAdduct formations of PtII complexes containing an aromatic diimine (DA) and an L‐amino acid (A) with an aromatic carboxylate (AR) or a mononucleotide (NMP) has been studied by synthetic, structural, spectroscopic, and calorimetric methods. Several adducts between PtII complexes, [Pt(DA)(L‐A)] (charges are omitted; DA=2,2′‐bipyrimidine (bpm); A=L‐arginine (L‐Arg), L‐alaninate (L‐Ala), and AR (=indole‐3‐acetate (IA), gentisate (GA)) or GMP were isolated as crystals and structurally characterized by the X‐ray diffraction method. GMP in [Pt(bpm)(Arg)](GMP)⋅5 H2O was revealed to be bound through the π–π stacking and guanidinium–phosphate hydrogen bonds. The [Pt(DA)(A)]‐AR and ‐NMP systems in aqueous solution exhibited NMR upfield shifts of the aromatic ring proton signals due to stacking. The stability constants (K) for the adducts were determined by absorption and NMR spectra and calorimetric titrations. The log K values were found to be in the range 1.40–2.29 for AR and 1.8–3.3 for NMP, the order for NMP being GMP>AMP>CMP>UMP. The ΔH ° values were negative for all the systems studied, and the values for AR (=IA and GA) were more negative than those for NMP, indicating that ARs are stronger electron donors than NMPs. Comparison of the log K values for [Pt(bpm)(L‐Arg)] and [Pt(bpm)(L‐Ala)] (Ala=alaninate) indicated that the Arg moiety further stabilized the adducts by the guanidinium–carboxylate or –phosphate hydrogen bonds. The combined effects of weak interactions on the stability of the adducts in solution are discussed on the basis of the thermodynamic parameters and solid state structures.
Amphiphilic Polymer Supports for the Asymmetric Hydrogenation of Amino Acid Precursors in Water
Authors: Zarka M. Tobias , Nuyken Oskar , Weberskirch Ralf 
Published: July 2003

AbstractThis paper describes the synthesis and characterization of a new class of amphiphilic, water‐soluble diblock copolymers based on 2oxazoline derivatives with pendent (2S,4S)‐4‐diphenylphosphino‐2‐(diphenylphosphinomethyl)pyrrolidine (PPM) units in the hydrophobic block. The synthetic strategy involves the preparation of a diblock copolymer precursor with ester functionalities in the side chain; which were converted into carboxylic acids in a polymer‐analogous step and finally reacted with the PPM ligand. The structures of the copolymers were characterized by 1H and 31P NMR spectroscopy and GPC measurements. Subsequently, these polymers were successfully utilized as a polymeric support for the asymmetric hydrogenation of 1) (Z)‐α‐acetamido cinnamic acid and 2) methyl (Z)‐α‐acetamido cinnamate in water, showing 90 % substrate conversion at 25 °C within 20 minutes at atmospheric H2 pressure (1 bar) for methyl (Z)‐α‐acetamido cinnamate.
The Use of Imidazolium Ionic Liquids for the Formation and Stabilization of Ir0 and Rh0 Nanoparticles: Efficient Catalysts for the Hydrogenation of Arenes
Authors: Fonseca Gledison S. , Umpierre Alexandre P. , Fichtner Paulo F. P. , Teixeira Sergio R. , Dupont Jairton 
Published: July 2003

AbstractStable transition‐metal nanoparticles of the type [M0]n are easily accessible through the reduction of IrI or RhIII compounds dissolved in “dry” 1‐n‐butyl‐3‐methylimidazolium hexafluorophosphate ionic liquid by molecular hydrogen. The formation of these [M0]n nanoparticles is straightforward; they are prepared in dry ionic liquid whereas the presence of the water causes the partial decomposition of ionic liquid with the formation of phosphates, HF and transition‐metal fluorides. Transmission electron microscopy (TEM) observations and X‐ray diffraction analysis (XRD) show the formation of [Ir0]n and [Rh0]n nanoparticles with 2.0–2.5 nm in diameter. The isolated [M0]n nanoparticles can be redispersed in the ionic liquid, in acetone or used in solventless conditions for the liquid–liquid biphasic, homogeneous or heterogeneous hydrogenation of arenes under mild reaction conditions (75 °C and 4 atm). The recovered iridium nanoparticles can be reused several times without any significant loss in catalytic activity. Unprecedented total turnover numbers (TTO) of 3509 in 32 h, for arene hydrogenation by nanoparticles catalysts, have been achieved in the reduction of benzene by the [Ir0]n in solventless conditions. Contrarily, the recovered Rh0 nanoparticles show significant agglomeration into large particles with a loss of catalytic activity. The hydrogenation of arenes containing functional groups, such as anisole, by the [Ir0]n nanoparticles occurs with concomitant hydrogenolysis of the CO bond, suggesting that these nanoparticles behave as “heterogeneous catalysts” rather than “homogeneous catalysts”.