bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cytological mechanisms of gynogenesis and sperm incorporation in unreduced diploid eggs of the clonal loach, Misgurnus anguillicaudatus (Teleostei: Cobitidae)
Authors: Itono Masaki , Okabayashi Naoki , Morishima Kagayaki , Fujimoto Takafumi , Yoshikawa Hiroyuki , Yamaha Etsuro , Arai Katsutoshi 
Published: November 2006

AbstractThe loach Misgurnus anguillicaudatus comprises diploid clonal, triploid and diploid–triploid mosaic individuals in a wild population on Hokkaido island, Japan. When diploid eggs of clonal loaches are fertilized by haploid sperm of normal bisexual loaches, both diploid clonal and non‐diploid aclonal individuals occur in the progeny. Flow cytometry and microsatellite analyses revealed that the occurrence of triploid, diploid–triploid and other progeny was essentially due to the genetic incorporation of sperm to diploid clonal genomes of unreduced eggs. In this study, we examined the influence of water temperature from fertilization to early embryogenesis on frequencies of diploid clonal and other progeny and observed that progeny of three out of four clonal females examined exhibited approximately constant rates of diploid clonal individuals (54.2–68.9%) at hatching stage. Thus, no drastic increase of non‐diploid progeny was detected. However, the 28°C group of the fourth clonal female gave significantly lower rate (28.1%) of diploid clonal progeny, suggesting that this temperature might be a critical or a borderline temperature inducing sperm incorporation. We also examined the cytological process by which diploid clonal and other aclonal progeny develop after fertilization. In some fertilized eggs, the sperm nucleus remained condensed throughout fertilization and early embryogenesis and never fused with the female pronucleus. This cytological observation concludes that clonal eggs develop by the mechanism of gynogenesis. However, some other eggs showed the cytological process of syngamy between the female pronucleus and an accidentally formed male nucleus, suggesting the formation of triploid progeny. The syngamy between an accidentally activated sperm nucleus with a male pronucleus‐like structure and nucleus of a blastomere of gynogenetically developing clonal diploid embryo might produce a diploid–triploid mosaic individual. J. Exp. Zool. 305A:35–50, 2007. © 2006 Wiley‐Liss, Inc.
Moving in social circles—social circle membership and performance implications
Authors: Verbeke Willem , Wuyts Stefan 
Published: November 2006

AbstractWe investigate social circles in intra‐firm settings. First, we argue that social circles are inhabited by individuals whose attitudes display fit with the objectives of the social circle rather than more self‐centered instrumentalism or calculation. For a test of this hypothesis, we distinguish between friendship circles and strategy‐influence circles. We find that friendship circle membership is positively associated with attitudes that display empathic concern but negatively with more instrumental attitudes, whereas strategy‐influence circle membership is positively associated with attitudes that display long‐term ambition but negatively with attitudes that display short‐term calculation. Second, we argue and find that membership of social circles affects individual performance (social circles foster the exchange of information, for which we find clear evidence), albeit not necessarily in a linear fashion. Our new insights into social circle membership and performance implications can guide individuals in seeking access to such social circles and can aid management in understanding and perhaps influencing intra‐firm knowledge flows. Copyright © 2006 John Wiley & Sons, Ltd.
On asymptotic properties of multidimensional α ‐stable densities
Authors: Zaigraev A. 
Published: November 2006

AbstractA class of multidimensional α ‐stable distributions is considered. The Poisson spectral measure of each distribution is assumed to be absolutely continuous with respect to the surface Lebesgue measure. The author concentrates his attention on the asymptotic behavior of the α ‐stable densities s (x) as |x | →∞and |x | → 0. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The coexistence problem for Heun's differential equation
Authors: Volkmer Hans 
Published: November 2006

AbstractFor certain parameter sets all solutions of Heun's equation are analytic in ℰ \ [0, 1], where ℰ is a (small) neighborhood of [0, 1]. These parameters sets are investigated. The results generalize those on coexistence of periodic solutions of the Lamé and Ince equations due to Ince, Magnus and Winkler. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Moving triangles over a sphere
Authors: Alonso Javier , Martín Pedro 
Published: November 2006

AbstractIf three points on a circle are rotated around the circle in such a way that the lengths of two sides of the triangle they define do not change, then neither does the length of the third side. If instead of a circle we consider the unit sphere of a norm in a two‐dimensional normed space, then the above property characterizes the ellipses. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Independent validation of SCOPA–psychosocial and metric properties of the PDQ‐39 Brazilian version
Authors: Carod‐Artal Francisco Javier , Martinez‐Martin Pablo , Vargas Antonio Pedro 
Published: November 2006

AbstractThe objective of this study was to perform an independent validation of the Scales for Outcomes in Parkinson's Disease–Psychosocial questionnaire (SCOPA‐PS) and assessment of the Parkinson's Disease Questionnaire (PDQ‐39), Brazilian version. Patients were evaluated by means of the Unified Parkinson's Disease Rating Scale, Hoehn and Yahr staging (HY), Schwab and England scale, Mini‐Mental State Examination, and Hospital Anxiety and Depression Scale. Health‐related quality of life was evaluated using the MOS‐Short Form 36 (SF‐36), PDQ‐39, and SCOPA‐PS. One hundred forty‐four patients were included (mean age, 62 years; 53.5% males; mean duration of illness, 6.6 years; HY, 1–4). Mean SCOPA‐PS and PDQ‐39 Summary Index (SI) were 39.2 and 40.7, respectively. The internal consistency of SCOPA‐PS (Cronbach's alpha = 0.84; item–total correlation, 0.44–0.73) and PDQ‐39 dimensions (alpha = 0.61–0.85; item–total correlation, 0.46–0.82) were satisfactory. Concerning the stability of the questionnaires, intraclass correlation coefficient (ICC) values were 0.71 for the SCOPA‐PS and 0.86 for the PDQ‐39 SI. ICC for PDQ‐39 dimensions ranged from 0.52 (social support) to 0.80 (stigma). Standard error of measurement (SEM) values for each PDQ‐39 dimension ranged from 0.49 (emotional well‐being) to 17.52 (social support). SEM values for SCOPA‐PS and PDQ‐39 SI were 11.84 and 6.72, respectively. A significant correlation of SCOPA‐PS and PDQ‐39 SI with the SF‐36 physical (−0.42 and −0.52, respectively) and mental components (−0.41) was found. Correlation between SCOPA‐PS and PDQ‐39 SI was 0.73 (all coefficients,P< 0.0001). The SCOPA‐PS and PDQ‐39, Brazilian versions, have satisfactory metric attributes. © 2006 Movement Disorder Society
Structural determination of silymins A and B, new pentacyclic triterpenes from Silybum marianum, by 1D and 2D NMR spectroscopy
Authors: Ahmed Ejaz , Noor Atia tun , Malik Abdul , Ferheen Sadia , Afza Nighat 
Published: November 2006

AbstractSilymins A (1) and B (2), the new pentacyclic triterpenes, have been isolated from ethyl acetate fraction of Silybum marianum and their structures assigned from 1H and 13C NMR spectra, DEPT and by 2D COSY, NOE and HMBC experiments. Copyright © 2007 John Wiley & Sons, Ltd.
Superabsorbent composite. X. Effects of saponification on properties of polyacrylamide/attapulgite
Authors: Zhang Junping , Li An , Wang Aiqin 
Published: November 2006

AbstractA novel superabsorbent composite from acrylamide (AM) and attapulgite (APT), polyacrylamide/attapulgite (PAM/APT), was prepared by polymerizing AM with the existence of APT in aqueous solution, and then saponified with NaOH solution. Considering the impacts of hydrophilic groups (COONa, COOH, and CONH2) on properties of the PAM/APT composite, the effects of saponification mode, molar ratio of NaOH to AM and saponification time on water absorbency, hydrophilic group content, and surface morphology were investigated systematically. The results indicate that the two‐step adding NaOH mode is superior to that of the one‐step mode. Among the superabsorbent composite incorporated with 30 wt% APT, the composite saponified at 95°C for 2 h with the molar ratio of 0.6 for NaOH to AM acquired the highest water absorbencies of 1715g g−1 and 87.8g g−1 in distilled water and in 0.9 wt% NaCl solution, respectively. The molar ratio of various hydrophilic groups at this time was 10:3:11 for COONa, COOH, and CONH2 determined using linear potentiometric titration method. POLYM. ENG. SCI. 46:1762–1767, 2006. © 2006 Society of Plastics Engineers.
Comparison of elastic and tactile behavior of human skin and elastomeric materials through tribological tests
Authors: Elleuch Khaled , Elleuch Riadh , Zahouani Hassan 
Published: November 2006

AbstractThe current article describes static and frictional contact tests carried out with spherical indenter on both human skin surface and elastomeric materials. This tribological study is performed to analyze the elasticity and tactile properties of the human skin, and therefore to evaluate reliability of human skin behavior simulation through the considered elastomeric materials. Finite element analyses of indentation tests are proposed. Critical normal load was found when numerical and experimental results were confronted. Such critical force defines the limit of elastic model application. POLYM. ENG. SCI., 46:1715–1720, 2006. © 2006 Society of Plastics Engineers
Injection molding of syndiotactic polystyrene/clay nanocomposites
Authors: Sorrentino Andrea , Pantani Roberto , Brucato Valerio 
Published: November 2006

AbstractThis study aims at exploring the effect of a commercial organoclay montmorillonite (MMT) on the final properties of syndiotactic polystyrene (sPS) injection‐molded samples. To this goal, injection‐molded specimens made from neat sPS and commercial MMT modified with various organic compounds were prepared in different molding conditions. Dispersion of clay was attained via melt blending, directly in the injection chamber of the injection‐molding machine. The obtained specimens were analyzed by IR spectroscopy, X‐ray diffraction, thermogravimetry, and differential thermal analysis, with the aim of elucidating the effect of clay on the microstructures of the samples. Results clearly show that, depending on the organic modification, the presence of clay can induce strong effects on final crystallinity. This behavior can be attributed mainly to the role played by clay on the kinetics of the crystallization process. Eventually, it was found that the addition of a small percentage of clay (1%) in sPS can substantially widen the processing window of the material. POLYM. ENG. SCI. 46:1768–1777, 2006. © 2006 Society of Plastics Engineers.
Recycling of high impact polystyrene in coextruded sheet: Influence of the number of processing cycles on the microstructure and macroscopic properties
Authors: Soriano Florentino , Morales Graciela , de León Ramón Díaz 
Published: November 2006

AbstractHigh impact polystyrene(HIPS) was repeatedly coextruded at 220°C, maintaining a constant composition of 70 wt% of virgin HIPS and 30 wt% of recycled HIPS. The gel content (GC), grafting degree (GD), swell index (SI), morphology of the rubber phase, and average molecular weight of the polystyrene (PS) matrix ($\bar{M}$w) were characterized after each processing cycle. The effect of these parameters on the melt flow index (MFI), the shear viscosity (η), the power law index (n), the Izod impact, and the stress at break were evaluated. The results demonstrated that the rheological properties changed with the number of processing cycles, e.g. the MFI decreased in the first cycle from 2.8 to 1.7 g/10 min, while from the second to the sixth cycle increased to 3.4 ± 0.2 g/10 min. The power law index increased from n = 0.29, after the first processing cycle, to n = 0.34 in the sixth cycle. The changes in MFI and n were attributed to changes in the physical structure of the rubber phase and to chain scissions in the PS matrix, caused by the recycling. Finally, the impact strength decreased with the increasing number of processing cycles, while the tensile stress at break remained constant. POLYM. ENG. SCI., 46:1698–1705, 2006. © 2006 Society of Plastics Engineers
Constitutive modeling for intercalated PMMA/clay nanocomposite foams
Authors: Jo Choonghee , Fu Jin , Naguib Hani E. 
Published: November 2006

AbstractA constitutive model for tensile behavior of PMMA/clay nanocomposite foams was developed in this study. The elastic modulus of the nanocomposites is affected by the form of clays embedded in the polymer matrix. The reinforcing effect by intercalation of the clays and the detrimental effect by clay agglomeration were considered for the determination of the elastic modulus of the nanocomposites. A viscoelastic model was adapted for the tensile behavior of the material. The developed constitutive equation is expressed in terms of clay morphology and material properties. The aspect ratio of clays and the expansion of clay layer spacing in the intercalated clay clusters were proved to play a vital role in the reinforcing mechanism. For the verification of the constitutive model, Poly(methyl‐methacrylate) (PMMA)/clay nanocomposite foams were manufactured by batch process method and their uniaxial tensile test results were compared with theoretical predictions. Compared with the experimental results, the proposed constitutive equation showed agreement with the experimental test results. POLYM. ENG. SCI. 46:1787–1796, 2006. © 2006 Society of Plastics Engineers.
Pro‐inflammatory cytokines and depression in a familial cancer registry
Authors: O'Connor Mary‐Frances , Irwin Michael R. , Seldon Joyce , Kwan Lorna , Ganz Patricia A. 
Published: November 2006

AbstractPatients undergoing cancer treatment (e.g., interferon or IL‐2 treatment) develop depression, and there is a positive relationship between their depression and circulating levels of proinflammatory cytokines. Depressed patients who are medically healthy also show increases in circulating markers of inflammation. The present study characterized baseline levels of inflammatory cytokine activity in 18 pairs of depressed and non‐depressed persons at high risk for cancer and matched for age, ethnicity and all unaffected by a personal history of cancer. Circulating levels of interleukin‐6 (IL‐6), soluble IL‐6 receptor (sIL‐6R), tumor necrosis factor‐α‐receptor (TNF‐RII), and soluble intercellular adhesion molecule (sICAM) did not differ between those with and without depression. The present data are important for characterizing persons at high risk for cancer who may later acquire knowledge of further increased risk through genetic testing. Copyright © 2006 John Wiley & Sons, Ltd.
Complementarity of hydrophobic properties in ATP‐protein binding: A new criterion to rank docking solutions
Authors: Pyrkov Timothy V. , Kosinsky Yuri A. , Arseniev Alexander S. , Priestle John P. , Jacoby Edgar , Efremov Roman G. 
Published: November 2006

AbstractATP is an important substrate of numerous biochemical reactions in living cells. Molecular recognition of this ligand by proteins is very important for understanding enzymatic mechanisms. Considerable insight into the problem may be gained via molecular docking simulations. At the same time, standard docking protocols are often insufficient to predict correct conformations for protein–ATP complexes. Thus, in most cases the native‐like solutions can be found among the docking poses, but current scoring functions have only limited ability to discriminate them from false positives. To improve the selection of correct docking solutions obtained with the GOLD software, we developed a new ranking criterion specific for ATP–protein binding. The method is based on detailed analysis of the intermolecular interactions in 40 high‐resolution 3D structures of ATP–protein complexes (the training set). We found that the most important factors governing this recognition are hydrogen‐bonding, stacking between adenine and aromatic protein residues, and hydrophobic contacts between adenine and protein residues. To address the latter, we applied the formalism of 3D molecular hydrophobicity potential. The results obtained were used to construct an ATP‐oriented scoring criterion as a linear combination of the terms describing these intermolecular interactions. The criterion was then validated using the test set of 10 additional ATP–protein complexes. As compared with the standard scoring functions, the new ranking criterion significantly improved the selection of correct docking solutions in both sets and allowed considerable enrichment at the top of the list containing docking poses with correct solutions. Proteins 2007. © 2006 Wiley‐Liss, Inc.
Long‐wavelength (λ ≥ 1.3 µm) InGaAlAs–InP vertical‐cavity surface‐emitting lasers for applications in optical communication and sensing
Authors: Amann Markus‐Christian , Ortsiefer Markus 
Published: November 2006

AbstractIn this paper we present an overview of the properties and applications of long‐wavelength vertical‐cavity surface‐emitting lasers (VCSELs) based on the InGaAlAs–InP material system. With respect to significant temperature sensitivity of active material gain as well as insufficient thermal conductivity of InP‐based epitaxial compound layers, the effective thermal heat management appears as a major issue for application suitable device performance. In this context, the incorporation of a buried tunnel junction (BTJ) in connection with improved heat sinking resembles a breakthrough for long‐wavelength VCSELs. With the utilization of n‐type spreading layers and consequently ultralow series resistances, BTJ‐VCSELs exhibit sharply reduced excess heat generation. Furthermore, the BTJ‐approach enables self‐aligned optical and current confinement. A hybrid dielectric stack with Au‐coating yields an improved thermal heatsinking. The current status of BTJ‐VCSELs encompasses a number of superior performance values. At 1.55 µm wavelength, this includes room temperature single‐ and multimode continuous wave (cw) output powers of more than 3 mW and 10 mW, respectively, laser operation for heat sink temperatures well exceeding 100 °C, and optical data transmission rates up to 10 Gbit/s. The versatility of compound layer composition enables arbitrary emission wavelengths within a broad range of 1.3 and 2 µm. With respect to sensing applications, BTJ‐VCSELs appear as ideal components for optical detection of infrared active gases. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Self‐assembled Si and SiGe nanostructures: New growth concepts and structural analysis
Authors: Bauer G. , Schäffler F. 
Published: November 2006

AbstractSelf‐organization during strained‐layer heteroepitaxy has been a field of intense research in the last few years. Especially the Si/SiGe heterosystem is considered a model system for strain‐driven Stranski–Krastanow growth. In this review article, we concentrate on ordered Stranski–Krastanow growth of Ge and SiGe islands on prepatterned Si(001) substrates, which provide preferential nucleation sites. Perfectly ordered SiGe dot arrays in two and three dimensions are demonstrated, and the basic mechanisms for preferential nucleation in geometrically well‐defined etch pits are discussed. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Directed graphs for the analysis of rigidity and persistence in autonomous agent systems
Authors: Hendrickx Julien M. , Anderson Brian D. O. , Delvenne Jean‐Charles , Blondel Vincent D. 
Published: November 2006

AbstractWe consider in this paper formations of autonomous agents moving in a two‐dimensional space. Each agent tries to maintain its distances toward a pre‐specified group of other agents constant and the problem is to determine if one can guarantee that the distance between every pair of agents (even those not explicitly maintained) remains constant, resulting in the persistence of the formation shape. We provide here a theoretical framework for studying this problem. We describe the constraints on the distance between agents by a directed graph and definepersistent graphs. A graph is persistent if the shapes of almost all corresponding agent formations persist. Although persistence is related to the classical notion of rigidity, these are two distinct notions. We derive various properties of persistent graphs, and give a combinatorial criterion to decide persistence. We also define minimal persistence (persistence with the least possible number of edges), and we apply our results to the interesting special case of cycle‐free graphs. Copyright © 2006 John Wiley & Sons, Ltd.
Beyond the “decorated landscapes” of educational reform: Toward landscapes of pluralism in science education
Authors: Mueller Michael P. , Bentley Michael L. 
Published: November 2006

AbstractPerhaps, we are at the fork in the road when it is imperative that we consider whether the pursuit of pluralism in science education is a worthwhile endeavor in light of recent educational reforms that seem to decorate the true aim of education. The “decorated landscapes” of educational reform concentrate on economic growth and do little to promote the conservation of Earth's natural environments that sustain life itself. Here we renew a discussion of a 300‐year pursuit in the United States toward educational landscapes that contribute to students' lives. We connect with scholars who have pursued the pluralistic landscapes of culture in an attempt to make education more authentic and democratic and with scholars who have pursued an education for the conservation of the Earth's natural environments. We argue that these two educational domains are and necessarily should be reflective, reliant, and reciprocal of each other if we wish to truly engage students in scientific literacy—the authentic, relevant, and meaningful science education experiences that contribute a person's existence. Finally, we offer recommendations which aim to focus on the many meaningful landscapes that contribute to pluralistic life in science education. © 2006 Wiley Periodicals, Inc. Sci Ed 91:321–338, 2007
A comparison of mixed‐effects quantile stratification propensity adjustment strategies for longitudinal treatment effectiveness analyses of continuous outcomes
Authors: Leon Andrew C. , Hedeker Donald 
Published: November 2006

AbstractThe propensity adjustment is used to reduce bias in treatment effectiveness estimates from observational data. We show here that a mixed‐effects implementation of the propensity adjustment can reduce bias in longitudinal studies of non‐equivalent comparison groups. The strategy examined here involves two stages. Initially, a mixed‐effects ordinal logistic regression model of propensity for treatment intensity includes variables that differentiate subjects who receive various doses of time‐varying treatments. Second, a mixed‐effects linear regression model compares the effectiveness of those ordinal doses on a continuous outcome over time. Here, a simulation study compares bias reduction that is achieved by implementing this propensity adjustment through various forms of stratification. The simulations demonstrate that bias decreased monotonically as the number of quantiles used for stratification increased from two to five. This was particularly pronounced with stronger effects of the confounding variables. The quartile and quintile strategies typically removed in excess of 80–90 per cent of the bias detected in unadjusted models; whereas a median‐split approach removed from 20 to 45 per cent of bias. The approach is illustrated in an evaluation of the effectiveness of somatic treatments for major depression in a longitudinal, observational study of affective disorders. Copyright © 2006 John Wiley & Sons, Ltd.