bluuebunny/crossref_metadata_2025_split huggingface dataset:
Extending the Calakmul Dynasty Back in Time: A New Stela from a Maya Capital in Campeche, Mexico
Authors: Pincemin Sophia , Marcus Joyce , Folan Lynda Florey , Folan William J. , Carrasco María del Rosario Domínguez , López Abel Morales 
Published: November 2006

The 200-year period from A.D. 230 to 430 witnessed the transition from chiefdom to state in the Maya Lowlands and the founding of several early political dynasties. Considerable information on that era is known for major cities like Tikal and Copán, but we knew less about the Calakmul area until recently. Previously, Calakmul's earliest dated monument was Stela 43, carved at A.D. 514. On the other hand, Tikal's earliest text dated to A.D. 292, and its ruling dynasty claimed that its founding date was A.D. 230. The ruling dynasties of most other cities that eventually became Maya regional capitals were evidently founded later, between A.D. 330 and 430.With the 1994 discovery of Stela 114 at Calakmul, we can now push Calakmul's written record back to A.D. 431. The oldest stela in Calakmul’s realm was erected in A.D. 406 at Balakbal, to document the reign of a Balakbal ruler who was a contemporary of the Tikal ruler Curl Snout. Some 25 years later, Calakmul erected Stela 114 to commemorate a Calakmul ruler who was a contemporary of the Tikal ruler Stormy Sky. Even though we had expected Calakmul's dynasty to have greater time depth than A.D. 514, it was not until the discovery of Stela 114 that we were able to confirm that point.
Influence of complexation on the composition of equilibrium phases in the system of Ce2(SO4)3-La2(SO4)3
Authors: Milanova Maria , Todorovsky Dimitar , Balarew Christo , Minkova Natalia , Ivanova Katya 
Published: November 2006

AbstractThe cocrystallization of Ce2(SO4)3 and La2(SO4)3 is studied in aqueous and H2SO4 (150 g/dm3) solutions at 25 °C and 64 °C. The effect of the formation of inner sphere sulfate complexes of the type LnSO 4+ in determining the composition of the equilibrium phases is revealed.
The effect of doping by IV-family elements on the electronic structure and electrical characteristics of Sb2O5
Authors: Du Juan , Ji Zhenguo , Wang Chao 
Published: November 2006

Abstract
The electronic structures of doped Sb2O5 by IV-family elements (Si, Ge and Sn) were examined using the density function theory (DFT). Density of states (DOSs) results showed that the substituted IV-family elements act as acceptors in Sb2O5. Partial DOSs indicates that by substituting Ge(GeSb) or Sn(SnSb), there may be a larger contribution to the total DOSs near EF than by substituting Si, which suggests that doping Ge or Sn in Sb2O5 produces better ptype doping compared to doping Si. Formation energy results show that IV-family elements are more likely to exist in the substituted position rather than in the interstitial position in Sb2O5, decreasing any self-compensation effect and making it easier for IV-family elements to realize ptype doping in Sb2O5. Ionization energy results show that GeSb or SnSb, two among the three impurities considered, act as shallow acceptors in Sb2O5, thus producing a higher concentration of holes.
The oscillatory galvanomagnetic size-effect in multilayered structures
Authors: Dekhtyaruk Leonid 
Published: November 2006

Abstract
Within the framework of the modified semi-classical Fuchs-Sondheimer model, we investigated theoretically the electrical resistivity of multilayered structures (MLS) consisting of alternating metallic layers (of different purity and different thicknesses) in a transverse magnetic field as functions of the ratio of the adjacent layer thicknesses and the magnetic field value. We have derived both a general formula (valid at arbitrary values of layer thicknesses) and asymptotic expressions that are valid when metallic layers are thick or thin compared with the electron mean free path. We found a non-monotonic behavior in the resistivity vs. the value of an applied magnetic field. As we demonstrated, this behavior is sensitive to the characteristics of the electron scattering in the interlayer interfaces in low magnetic fields. Moreover, the MLS resistivity oscillates in high magnetic fields with the field value (or with the layer thicknesses). The oscillation includes the harmonics that correspond both to the each layer thicknesses and the total thickness. The intensity of the oscillation is determined by the diffusive electron scattering in the interfaces, and the oscillation amplitude is proportional to the coefficient of the electron transmission through the interlayer interfaces. We have calculated numerically the resistivity in a wide range of fields and layer thicknesses at various values of the parameters of the interface and bulk electron scattering.
Electronic transport mechanism in polydiacetylene crystals — variable range hopping or phonon-assisted tunnelling
Authors: Pipinys Povilas , Kiveris Antanas 
Published: November 2006

Abstract
Experimental results on the current-voltage characteristics of polydiacetylene (PDA) single crystals reported by Aleshin et al [Phys. Rev. Vol. B 69, (2004) art. 214203] are reinterpreted in terms of the phonon-assisted electron tunnelling model. It is shown that the experimental results, measured in the temperature range from 1.8 K to 300 K are consistent with the tunnelling rate dependence on field strength, computed for the same range of temperatures. An advantage of this model over that of Aleshin et al, using the variable range hopping (VRH) model, is the possibility of describing the behaviour of I — V data measured at both high and low temperatures with the same set of parameters characterizing this material. This assertion is confirmed by comparison of the temperature-dependent current-voltage data extracted from Aleshin et al’s work with tunnelling rate dependence on temperature, computed using two different expressions of the phonon-assisted tunnelling theory. The temperature dependence of the conductivity of an ion implanted PDA crystals [B. S. Elman et al, Appl. Phys. Lett., Vol. 46, (1985) p. 100] and polypyrrole [P. Dutta et al, Synth. Met., Vol. 139 (2003) p. 201] are also explained on the basis of this model.
Amplification of solitary optical waves in fibers with positive group velocity dispersion
Authors: Arabadzhiev Todor , Uzunov Ivan 
Published: November 2006

Abstract
Solitary optical waves with characteristic red frequency shift have been numerically identified in fibers with positive group velocity dispersion in the presence of amplification by semiconductor amplifiers. Influence of the Henry factor, the net gain, gain saturation characteristics, and frequency modulation on the frequency shift of the observed solitary optical waves has been examined. Normalized pulse energy as a function of the gain saturation characteristics has been studied.
Spectroscopic studies of D-α-tocopherol concentration-induced transformation in egg phosphatidylcholne vesicles
Authors: Dwiecki Krzysztof , Górnas Paweł , Wilk Agnieszka , Nogala-Kałucka Małgorzata , Polewski Krzysztof 
Published: November 2006

AbstractThe effects of embedding up to 60 mol% of α-tocopherol (α-Toc) on the morphology and structure of the egg phosphatidylcholine (PC) membrane were studied using spectroscopic techniques. The resulting vesicles were subjected to turbidometric and dynamic light scattering measurements to evaluate their size distribution. The α-Toc intrinsic fluorescence and its quenching was used to estimate the tocopherol position in the membrane. Optical microscopy was used to visualize morphological changes in the vesicles during the inclusion of tocopherol into the 2 mg/ml PC membrane. The incorporation of up to 15 mol% of tocopherol molecules into PC vesicles is accompanied by a linear increase in the fluorescence intensity and the simultaneous formation of larger, multilamellar vesicles. Increasing the tocopherol concentration above 20 mol% induced structural and morphological changes leading to the disappearance of micrometer-sized vesicles and the formation of small unilamellar vesicles of size ranging from 30 to 120 nm, mixed micelles and non-lamellar structures.
Deformation of Top‐Down and Bottom‐Up Silver Nanowires
Authors: Leach A. M. , McDowell M. , Gall K. 
Published: November 2006

AbstractAtomistic simulations are employed to probe the deformation behavior of experimentally observed top‐down and bottom‐up face‐centered cubic silver nanowires. Stable, <110> oriented nanowires with a rhombic and truncated‐rhombic cross section are considered, representative of top‐down geometries, as well as the multiply twinned pentagonal nanowire that is commonly fabricated in a bottom‐up approach. The tensile deformation of a stable, experimentally observed structure is simulated to failure for each nanowire structure. A detailed, mechanistic explanation of the initial defect nucleation is provided for each nanowire. The three geometries are shown to exhibit different levels of strength and to deform by a range of mechanisms depending on the nanowire structure. In particular, the deformation behavior of top‐down and bottom‐up nanowires is shown to be fundamentally different. The yield strength of nanowires ranging from 1 to 25 nm in diameter is provided and reveals that in addition to cross‐sectional diameter, the strength of the nanowires is strongly tied to the structure. This study demonstrates that nanowire structure and size may be tailored for specific mechanical requirements in nanometer‐scale devices.
People who judge people
Authors: Weiss David J. , Shanteau James , Harries Priscilla 
Published: November 2006

AbstractExperts who judge people usually provide opinions. It can be challenging to evaluate the professional performance of those experts, because for many domains there is no applicable external standard against which to verify the opinions. We review traditional methods for assessment and propose the purely empirical CWS approach as an alternative. Expert judgment entails discriminating among the various stimuli within the domain as well as being consistent when judging similar stimuli. We combine observed measures of these two components to form a ratio that we call the CWS index of expertise. We demonstrate the value of the index in an analysis of prioritization judgments made by occupational therapy students before and after they received specific training. The students' CWS scores improved considerably after training. The promise of the index as a selection tool is supported by the positive correlation of pre‐training scores with both post‐training scores and with course grades. Copyright © 2006 John Wiley & Sons, Ltd.
Polytomous Disease Mapping to Detect Uncommon Risk Factors for Related Diseases
Authors: Dreassi Emanuela 
Published: November 2006

AbstractA statistical model for jointly analysing the spatial variation of incidences of three (or more) diseases, with common and uncommon risk factors, is introduced. Deaths for different diseases are described by a logit model for multinomial responses (multinomial logit or polytomous logit model). For each area and confounding strata population (i.e. age‐class, sex, race) the probabilities of death for each cause (the response probabilities) are estimated. A specic disease, the one having a common risk factor only, acts as the baseline category. The log odds are decomposed additively into shared (common to diseases different by the reference disease) and specic structured spatial variability terms, unstructured unshared spatial terms and confounders terms (such as age, race and sex) to adjust the crude observed data for their effects. Disease specic spatially structured effects are estimated; these are considered as latent variables denoting disease‐specic risk factors.The model is presented with reference to a specic application. We considered the mortality data (from 1990 to 1994) relative to oral cavity, larynx and lung cancers in 13 age groups of males, in the 287 municipalities of Region of Tuscany (Italy). All these pathologies share smoking as a common risk factor; furthermore, two of them (oral cavity and larynx cancer) share alcohol consumption as a risk factor. All studies suggest that smoking and alcohol consumption are the major known risk factors for oral cavity and larynx cancers; nevertheless, in this paper, we investigate the possibility of other different risk factors for these diseases, or even the presence of an interaction effect (between smoking and alcohol risk factors) but with different spatial patterns for oral and larynx cancer. For each municipality and age‐class the probabilities of death for each cause (the response probabilities) are estimated. Lung cancer acts as the baseline category. The log odds are decomposed additively into shared (common to oral cavity and larynx diseases) and specic structured spatial variability terms, unstructured unshared spatial terms and an age‐group term.It turns out that oral cavity and larynx cancer have different spatial patterns for residual risk factors which are not the typical ones such as smoking habits and alcohol consumption. But, possibly, these patterns are due to different spatial interactions between smoking habits and alcohol consumption for the first and the second disease. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Microsolvation of an Ionic Dopant in Small 4He Clusters: OH+(3Σ)(4He)N via Genetic Algorithm Optimizations
Authors: Marinetti Fabio , Bodo Enrico , Gianturco Franco A. 
Published: November 2006

AbstractThe optimized spatial structures of the small clusters (with N up to 33) formed by an increasing number of 4He atoms, which act as a microsolvent surrounding the OH+ ionic molecular dopant, are obtained using a sum‐of‐potentials scheme corrected by three‐body (3B) effects. The most stable structures are generated using the type of genetic algorithm described herein, and the sequential formation of regular shell structures is analyzed in detail. Possible quantum corrections for both the solvent distributions and the stable energetics are analyzed and discussed.
Local Structure and Thermodynamics of a Core‐Softened Potential Fluid: Theory and Simulation
Authors: Zhou Shiqi , Jamnik Andrej , Wolfe Elie , Buldyrev Sergey V. 
Published: November 2006

AbstractPhase behavior and structural properties of homogeneous and inhomogeneous core‐softened (CS) fluid consisting of particles interacting via the potential, which combines the hard‐core repulsion and double attractive well interaction, are investigated. The vapour–liquid coexistence curves and critical points for various interaction ranges of the potential are determined by discrete molecular dynamics simulations to provide guidance for the choice of the bulk density and potential parameters for the study of homogeneous and inhomogeneous structures. Spatial correlations in the homogeneous CS system are studied by the Ornstein‐Zernike integral equation in combination with the modified hypernetted chain (MHNC) approximation. The local structure of CS fluid subjected to diverse external fields maintaining the equilibrium with the bulk CS fluid are studied on the basis of a recently proposed third order+second order perturbation density functional approximation (DFA). The accuracy of DFA predictions is tested against the results of a grand canonical ensemble Monte Carlo simulation. Reasonable agreement between the results of both methods proves that the DFA theory applied in this work is a convenient theoretical tool for the investigation of the CS fluid, which is practically applicable for modeling numerous real systems.
Treatment of new‐onset type 1 diabetes with peptide DiaPep277® is safe and associated with preserved beta‐cell function: extension of a randomized, double‐blind, phase II trial
Authors: Raz I. , Avron A. , Tamir M. , Metzger M. , Symer L. , Eldor R. , Cohen I. R. , Elias D. 
Published: November 2006

AbstractBackgroundTreatment with DiaPep277®, a peptide derived from HSP60, has been shown to preserve beta‐cell function in non‐obese diabetic mouse (NOD) mice and in a trial with newly diagnosed human patients with type 1 diabetes treated over a 10‐month period. This article extends the clinical trial observations to a total of 20 months of treatment to determine the safety and the effects of repeated doses of DiaPep277 on endogenous insulin secretion, metabolic control, and exogenous insulin requirements.MethodsThirty‐five male patients (aged 16–58) with a basal C‐peptide greater than 0.1 nmol/L were assigned to periodic treatment with DiaPep277 (1 mg) or placebo for a 12‐month treatment and 18‐month observation protocol, later extended to an additional year of treatment. Stimulated C‐peptide, HbA1c, and an exogenous insulin dose were the clinical endpoints.ResultsAt 18 months, stimulated C‐peptide concentrations had fallen in the placebo group (p = 0.0005) but were maintained in the DiaPep277 group. The need for exogenous insulin was higher in the placebo group than in the DiaPep277 group. Mean HbA1c concentrations were similar in both groups. After extension of the study, patients continuing treatment with DiaPep277 and those switched from placebo to DiaPep277 manifested a trend towards a greater preservation of beta‐cell function compared to patients maintained on or switched to placebo. The safety profile of DiaPep277 was similar between the treatment and placebo groups, and no drug‐related adverse events occurred.ConclusionsPeriodic treatment of subjects with DiaPep277 over 2 years was safe and associated preservation of endogenous insulin secretion up to 18 months was observed. Copyright © 2007 John Wiley & Sons, Ltd.
A New Synthetic Approach to High‐Purity (15R)‐Latanoprost
Authors: Martynow Jacek G. , Jóźwik Julita , Szelejewski Wiesław , Achmatowicz Osman , Kutner Andrzej , Wiśniewski Krzysztof , Winiarski Jerzy , Zegrocka‐Stendel Oliwia , Gołębiewski Piotr 
Published: November 2006

AbstractThis paper describes a new synthesis of latanoprost (1) that afforded high purity latanoprost in 16.9 % overall yield in eight synthetic steps from sulfone 4. The “α chain” in a derivative of the (–)‐“Corey lactone” was elongated first, followed by the attachment of a novel, enantiomerically pure “ω chain” synthon. This ensured the absence of the undesired (15S)‐1 diastereomer in the synthesized prostaglandin. The crystalline nature of the novel sulfone 4 facilitated its purification. A variation of the new synthesis of latanoprost is described, where the laboratory‐scale synthesis was further adapted to a hundred‐gram scale. In the course of the present synthesis, a new prostaglandin sulfone intermediate, 21, which may find application in the synthesis of diverse prostaglandin analogs, was introduced. A practical synthesis of novel, enantiomerically pure “ω chain” synthons 15, 16, and 17 has also been carried out, employing diol 12, which was obtained from derivatives of the D‐mannitol chiral pool. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
C‐Disaccharides as Probes for Carbohydrate Recognition – Investigation of the Conformational Requirements for Binding of Disaccharide Mimetics of Sialyl Lewis X
Authors: Denton Richard W. , Cheng Xuhong , Tony Kurissery A. , Dilhas Anna , Hernández Juan José , Canales Angeles , Jiménez‐Barbero Jesús , Mootoo David R. 
Published: November 2006

AbstractA set of C‐disaccharide analogs was designed to probe the recognition of a known O‐disaccharide mimetic of sialyl Lewis X, to P‐selectin. The synthesis of the C‐glycosides centered on the de novo construction of the galactose residue via an oxocarbenium ion/enol ether cyclization. Conformational analysis was performed by a combination of NMR spectroscopy and molecular mechanics (MM) and molecular dynamics (MD) calculations. The inhibition of P‐selectin binding was evaluated in a P‐selectin Biacore assay. At 12 mM, the O‐glycoside showed 48 % inhibition of binding, while the C‐glycoside analogs exhibited between 25–31 % inhibition. This data is discussed within the context of the active conformation of sLex and the conformational behavior of these ligands. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Preconcentration Electroanalysis at Surfactant‐Templated Thiol‐Functionalized Silica Thin Films
Authors: Etienne Mathieu , Cortot Jérôme , Walcarius Alain 
Published: November 2006

AbstractSurfactant‐templated thiol‐functionalized silica thin films have been deposited by spin‐coating on glassy carbon electrodes. Their permeability properties have been characterized using three solution phase redox probes (Ru(NH3), Fe(CN), FcMeOH) and their suitability to be applied for preconcentration electroanalysis has been studied using Ag+ as model analyte. Both the film permeability to redox probes and the performance of the modified electrodes towards Ag+ sensing were found to be dramatically influenced by the composition of the sol used for preparing the thin films, and especially its surfactant content. The best results were obtained with materials prepared from rather high surfactant concentration because they led (after template removal) to highly open mesoporous deposits with readily accessible thiol groups in the mesopore channels. The effect of various parameters on the electrode response have been investigated, including the composition of the detection medium, the accumulation time, the level of functionalization of the films and their preparation conditions, and the analyte concentration. A linear response for Ag+ was obtained in the 0.2–10 μM concentration range.
One‐step production of alkoxylated ethyl acetate with narrow adduct distribution
Authors: Xia Yong‐Mei , Shen Yong‐An , Ji Shi‐Run , Fang Yun , Wang Yi‐You , Tan Bing 
Published: November 2006

AbstractOligo‐ethylene/propylene glycol ethyl ether acetate (oligo‐EGEEA and oligo‐PGEEA) used to be synthesized in a two‐step process with acetic acid as starting material. This paper describes a one‐step production process catalyzed by the AlMg composite oxide, achieved by alkoxylation of ethyl acetate directly. Aiming at a narrow adduct distribution to get high product selectivity of mono‐derivatives, the alkoxylation parameters, such as the Al/Mg molar ratio of the catalyst, molar ratio of reactants, temperature, initial reaction pressure, and reactant feed rate were investigated. The highest content of mono‐ and di‐derivatives in the products was: w (oligo‐EGEEA) = 73.8%, w (oligo‐PGEEA) = 87.9%, respectively. The product selectivity of mono‐EGEEA was decreased by only 5% after reusing the catalyst for ten runs. A 1.26‐fold increase in the yield of mono‐PGEEA was achieved by treating the catalyst surface with alcoholic potash. Copyright © 2006 Society of Chemical Industry