bluuebunny/crossref_metadata_2025_split huggingface dataset:
PLANT SUCCESSION AFTER HYDROLOGIC DISTURBANCE: INFERENCES FROM CONTEMPORARY VEGETATION ON A CHRONOSEQUENCE OF BARS, WILLAMETTE RIVER, OREGON, USA
Authors: Cline S. P. , McAllister L. S. 
Published: June 2011

ABSTRACTHistoric unconstrained, unregulated streamflow along the upper Willamette River, Oregon produced a floodplain of coalescent bars supporting a mosaic of vegetation patches. We sampled 42 bars and adjacent floodplain that formed recently to >64 years ago in four >1‐km‐long reaches to assess differences in vegetation and bar characteristics. Bar disturbance and environmental factors (streamflow, precipitation and regional climate indices) were estimated within six aerial photo intervals between 1936 and 2006. Black cottonwood (Populus balsamifera ssp. trichocarpa) and Salix species rapidly colonized new and disturbed bars, and independent estimates of bar and vegetation age were positively correlated across photo intervals (R2 = 0.95). Overstory communities varied with age: Populus–Salix spp. on gravel bars (trees aged 9–16 years [interquartile range]), Populus on islands (24–45 years), Populus/Acer–Fraxinus on islands coalesced to floodplain (49–72 years) and Acer–Populus on adjacent floodplain forested since 1936 (64–102 years). Meanwhile, bar height, silt/clay fraction, overstory basal area and community wetland prevalence index (WPI) increased. We identified a common but distinct Pacific willow (Salix lucida ssp. lasiandra) community (30–43 years) associated with back channels and island tails. Six understory communities varied by age and by WPI within age strata; in these communities 55–75% of total cover was introduced species, predominantly Phalaris arundinacea and Rubus armeniacus. Vegetation resets occurred in all photo intervals and affected 31% of sampled bars. Mean bar disturbance rate, Q1.5 frequency, precipitation and the Pacific Decadal Oscillation index followed cyclic trends across photo intervals whereas Qmax decreased linearly and relatively fewer, younger bars were disturbed. Results suggest that Populus patch initiation is ongoing but channel stability may be hindering the long‐term self‐sustainability of plant communities associated with the upper Willamette's historic shifting habitat mosaic. Published in 2011 by John Wiley & Sons, Ltd.
Portraying real science in science communication
Authors: Dijk Esther M. van 
Published: June 2011

AbstractIn both formal and informal settings, not only science but also views on the nature of science are communicated. Although there probably is no singular nature shared by all fields of science, in the field of science education it is commonly assumed that on a certain level of generality there is a consensus on many features of science. In this paper, it will be argued that because of their focus on unifying items and their ignoring of the actual heterogeneity of science, it is questionable whether such consensus views can fruitfully contribute to the aim of science communication, i.e., to enhance the public's functional scientific literacy. The possibilities of an alternative approach to the portrayal of the sciences within science communication are explored. © 2011 Wiley Periodicals, Inc. Sci Ed 95:1086–1100, 2011
Influence of Manganese and Nickel on the α´ Martensite Transformation Temperatures of High Alloyed Cr‐Mn‐Ni Steels
Authors: Jahn Andreas , Kovalev Alexander , Weiß Andreas , Scheller Piotr R. 
Published: June 2011

AbstractThe martensite start temperature (Ms), the martensite austenite re‐transformation start temperature (As) and the re‐transformation finish temperature (Af) of six high alloyed Cr‐Mn‐Ni steels with varying Ni and Mn contents in the wrought and as‐cast state were studied. The aim of this investigation is the development of the relationships between the Ms, As, Af, T0 temperatures and the chemical composition of a new type of Cr‐Mn‐Ni steels. The investigations show that the Ms, As and Af temperatures decrease with increasing nickel and manganese contents. The Af temperature depends on the amount of martensite. Regression equations for the transformation temperatures are given. The experimental results are based on dilatometer tests and microstructure investigations.
Development of Porous Ceramic Preforms Based on Magnesia Partially Stabilised Zirconia with Additions of MgAl2O4, MgO, Al2O3 and Ti
Authors: Wenzel Claudia , Aneziris Christos G. 
Published: June 2011

AbstractThe present paper deals with the development of metal matrix composites with improved mechanical properties based on metastable austenitic TRIP‐steel and magnesia partially stabilised zirconia. The ceramic material is characterised regarding the influence of different additives (MgAl2O4, MgO, Al2O3) on the monoclinic/tetragonal/cubic phase composition. First results for the infiltration of ceramic preforms are shown, on the one hand performed by conventional steel casting technology and on the other hand by submerging of preforms in a metal melt using a steel casting simulator.
The globalization of science education
Authors: DeBoer George E. 
Published: June 2011

AbstractStandards‐based science education, with its emphasis on monitoring and accountability, is rapidly becoming a key part of the globalization of science education. Standards‐based testing within countries is increasingly being used to determine the effectiveness of a country's educational system, and international testing programs such as Programme for International Student Assessment (PISA) and Trends in Mathematics and Science Study (TIMSS) enable countries to compare their students to a common standard and to compete among themselves for top scores. The raising of standards and the competition among countries is driven in part by a belief that economic success depends on a citizenry that is knowledgeable about science and technology. This article considers the question of whether it is possible and prudent to begin conversations about what an international standards document for global citizenship in science education might look like. It examines current practices in a range of countries to show both the areas of international agreement and the significant differences that exist. It concludes with a recommendation that such conversations should begin, with the goal of creating a document that lays out the knowledge and competencies that international citizens should have but yet that gives space to individual countries to pursue goals that are unique to their own setting. © 2011 Wiley Periodicals, Inc., Inc. J Res Sci Teach 48: 567–591, 2011
Exploring Indian secondary teachers' orientations and practice for teaching science in an era of reform
Authors: Nargund‐Joshi Vanashri , Rogers Meredith A. Park , Akerson Valarie L. 
Published: June 2011

AbstractIn 2005 India introduced a new National Curriculum Framework aimed at providing a more constructivist approach to learning for all subjects. Previous research on the impact of curriculum reform in other countries (e.g., United States) concluded that for reform to be successful teachers' orientations toward teaching and learning must be considered early on. The purpose of our study was to heed this advice and initiate an exploration into Indian secondary science teachers' science teaching orientations by examining the orientations of two secondary science teachers and how they are reflected in their practice. Three questions guided our study: (1) What are the two Indian Secondary Science teachers' orientations toward teaching and learning of science? (2) To what extent are their orientations consistent with their practice? (3) In what ways, if at all, do their orientations and practice align with the goals of reform outlined in India's National Curriculum Framework? Data sources included semi‐structured interviews, classroom observations, and various artifacts. We found the teachers' orientations aligned with the goals of reform, but their classroom practice did not align with their orientations or the goals of reform, perhaps as a result of the many external constraints the teachers' felt were placed on them. From these findings we discuss implications for professional development that consider alignment for all three components while taking into account possible culture specific hindrances. © 2011 Wiley Periodicals, Inc., Inc. J Res Sci Teach 48: 624–647, 2011
Life‐cycle exposure to the estrogenic mycotoxin zearalenone affects zebrafish (Danio rerio) development and reproduction
Authors: Schwartz Patrick , Bucheli Thomas D. , Wettstein Felix E. , Burkhardt‐Holm Patricia 
Published: June 2011

AbstractZearalenone (ZON) is one of the worldwide most common mycotoxin and exhibits estrogenic activity in the range of natural steroid estrogens. The occurrence of ZON has been reported in soil, drainage water, wastewater effluents, and rivers, but its ecotoxicological effects on fish have hardly been investigated. The consequences of continuous long‐term ZON exposure, including a subsequent depuration period, as well as transgenerational effects of F0 short‐term exposure on F1 generation were investigated. Effects on growth, reproduction activity, physiology, and morphology of zebrafish (Danio rerio) were examined in a 182 day live‐cycle experiment. Life‐long exposure to ZON for 140 days increased wet weight, body length, and condition factor of female fish at 1000 ng/L, and sex ratio was shifted toward female from 320 ng/L ZON. Only females at 1000 ng/L ZON revealed a 1.5‐fold induction of plasma vitellogenin (VTG). Relative fecundity at 1000 ng/L recovered significantly during the depuration period. An increased condition factor in adult female F1 fish implies that exposure of F0 generation to 1000 ng/L ZON affected growth of F1 generation. A negative correlation between relative fecundity in the F1 generation (all groups exposed to 320 ng/L ZON) and the nominal ZON concentrations of the F0 exposure might indicate an influence of F0 exposure on reproductive performance of F1 generation. No exposure scenario affected fertility, hatch, embryo survival, and gonad morphology of zebrafish. Evaluating the environmental relevance of this data, the risk for fish to be harmed by exposure to ZON solely seems rather marginal, but ZON might contribute to the overall estrogenicity in the environment. © 2011 Wiley Periodicals, Inc. Environ Toxicol 2013.
A detailed analytical and simulation study of geographic random forwarding
Authors: Casari Paolo , Nati Michele , Petrioli Chiara , Zorzi Michele 
Published: June 2011

ABSTRACTIn this paper, we extend previous work on geographic random forwarding (GeRaF) by considering a more efficient paradigm whereby on/off cycles are exploited and every node can participate to packet relaying, as long as it wakes up during any handshake procedure. The protocol is fully distributed, as routing decisions are made hop by hop based on geographic metrics and using a joint channel access/routing procedure, like in the first version of GeRaF. In addition, a previously defined analytical model for GeRaF is used to analyze the protocol, after extending it to cover the new channel access and relay selection procedure. The model is employed to find optimal choices for the parameters of the protocol, before comparing analytical results with ns2 simulations. Results confirm that the geographic paradigm remains a very good solution for energy‐constrained, density‐constrained, and latency‐constrained networks, and that small yet very effective protocol optimizations can achieve remarkable performance improvements. Copyright © 2011 John Wiley & Sons, Ltd.
Ferric reductase genes involved in high‐affinity iron uptake are differentially regulated in yeast and hyphae of Candida albicans
Authors: Jeeves Rose E. , Mason Robert P. , Woodacre Alexandra , Cashmore Annette M. 
Published: June 2011

AbstractThe pathogenic yeast Candida albicans possesses a reductive iron uptake system which is active in iron‐restricted conditions. The sequestration of iron by this mechanism initially requires the reduction of free iron to the soluble ferrous form, which is catalysed by ferric reductase proteins. Reduced iron is then taken up into the cell by a complex of a multicopper oxidase protein and an iron transport protein. Multicopper oxidase proteins require copper to function and so reductive iron and copper uptake are inextricably linked. It has previously been established that Fre10 is the major cell surface ferric reductase in C. albicans and that transcription of FRE10 is regulated in response to iron levels. We demonstrate here that Fre10 is also a cupric reductase and that Fre7 also makes a significant contribution to cell surface ferric and cupric reductase activity. It is also shown, for the first time, that transcription of FRE10 and FRE7 is lower in hyphae compared to yeast and that this leads to a corresponding decrease in cell surface ferric, but not cupric, reductase activity. This demonstrates that the regulation of two virulence determinants, the reductive iron uptake system and the morphological form of C. albicans, are linked. Copyright © 2011 John Wiley & Sons, Ltd.
Saccharomyces cerevisiae engineered for xylose metabolism requires gluconeogenesis and the oxidative branch of the pentose phosphate pathway for aerobic xylose assimilation
Authors: Hector Ronald E. , Mertens Jeffrey A. , Bowman Michael J. , Nichols Nancy N. , Cotta Michael A. , Hughes Stephen R. 
Published: June 2011

AbstractSaccharomyces strains engineered to ferment xylose using Scheffersomyces stipitis xylose reductase (XR) and xylitol dehydrogenase (XDH) genes appear to be limited by metabolic imbalances, due to differing cofactor specificities of XR and XDH. The S. stipitis XR, which uses both NADH and NADPH, is hypothesized to reduce the cofactor imbalance, allowing xylose fermentation in this yeast. However, unadapted S. cerevisiae strains expressing this XR grow poorly on xylose, suggesting that metabolism is still imbalanced, even under aerobic conditions. In this study, we investigated the possible reasons for this imbalance by deleting genes required for NADPH production and gluconeogenesis in S. cerevisiae. S. cerevisiae cells expressing the XR–XDH, but not a xylose isomerase, pathway required the oxidative branch of the pentose phosphate pathway (PPP) and gluconeogenic production of glucose‐6‐P for xylose assimilation. The requirement for generating glucose‐6‐P from xylose was also shown for Kluyveromyces lactis. When grown in xylose medium, both K. lactis and S. stipitis showed increases in enzyme activity required for producing glucose‐6‐P. Thus, natural xylose‐assimilating yeast respond to xylose, in part, by upregulating enzymes required for recycling xylose back to glucose‐6‐P for the production of NADPH via the oxidative branch of the PPP. Finally, we show that induction of these enzymes correlated with increased tolerance to the NADPH‐depleting compound diamide and the fermentation inhibitors furfural and hydroxymethyl furfural; S. cerevisiae was not able to increase enzyme activity for glucose‐6‐P production when grown in xylose medium and was more sensitive to these inhibitors in xylose medium compared to glucose. Published in 2011 by John Wiley & Sons, Ltd.
The control variational method for beams in contact with deformable obstacles
Authors: Barboteu M. , Sofonea M. , Tiba D. 
Published: June 2011

AbstractWe consider a mathematical model which describes the equilibrium of an elastic beam in contact with two obstacles. The contact is modeled with a normal compliance type condition in such a way that the penetration is allowed but is limited. We state the variational formulation of the problem and prove an existence and uniqueness result for the weak solution. Then, we provide an alternative approach to the model, based on the control variational method. Necessary and sufficient optimality conditions are derived, together with an approximation property. We also adapt our results to some versions of the model which describe the contact with a single obstacle. For this type of problems we present two methods of numerical approach, based on the iterative control variational method and the Newton method, respectively, and provide numerical simulations for the two algorithms.
The homogenized equations of motion for an activated elastic lamination in plane strain
Authors: Sanguinet W.C. 
Published: June 2011

AbstractThe equations of motion for an elastic laminar spatial‐temporal composite are investigated. It is assumed that the composite is binary, that is, it is assembled of two original constituents capable of changing (in space‐time) their material density, as well as their material stiffness. The condition of plane strain was then imposed on the composite. The paper begins by attempting to evaluate the materials' average Lagrangian (action density). In doing so, it immediately becomes apparent that expressions are needed for average momentum and stress. Both quantities are found to depend linearly on average strain and average velocity. After calculating the general Euler equations of motion, isotropy was assumed, and two additional forces (one being of a Coriolis nature) were found in the averaged equations of elastodynamics due to the presence of simultaneous change in both inertial and elastic properties of the original material constituents. The appearance of these two forces is a consequence of both dynamics and plane strain; the Coriolis type force disappears in the case of one dimensional strain that arises when longitudinal dynamic disturbances propagate along an elastic bar.
Dynamics of mechanical systems with nonlinear nonholonomic constraints – I The history of solving the problem of a material realization of a nonlinear nonholonomic constraint
Authors: Zeković D.N. 
Published: June 2011

AbstractThe paper brings forth a detailed analysis of the solution of the problem of the material realization of a nonlinear nonholonomic constraint (NNC). The existing models of the NNC are shown that can be classified into two groups: the first group comprises correctly realized physical models, while the second group contains the so‐called “quasinonlinear” nonholonomic constraints which in fact represent mathematical models. The correctness of the cited models is considered in detail, and the essential nature of such constraints, the basic of which is holonomic, is shown. The second group of models, i.e., the “quasinonlinear” NC (nonholonomic constraints) in fact represents the given program of motion, while the additional force, which carries out the program, has the analytical form of the reaction of the NNC. That is why are presented the models of the NNC which possess a clear physical sense, on the basis of which certain statements on the method of variation and the reaction of the NNC can be given. With regard to the clear physical sense and the nature of the models cited, the NNC that come out of them are used quite normally in the analysis of motion of such a system. The cited models, together with standard models oh nonholonomic Mechanics (sphere, disk, blade) make a group of basic nonholonomic constraints which can be classified, according to the three criteria, into certain types. Finally, it is shown that the cited model can be used for the construction of “nonholonomic chains”, both open and closed ones.
Expression and fermentation optimization of oxidized polyvinyl alcohol hydrolase in E. coli
Authors: Yang Yu , Zhang Dongxu , Liu Song , Jia Dongxu , Du Guocheng , Chen Jian 
Published: June 2011

Abstract
Oxidized polyvinyl alcohol (PVA) hydrolase (OPH) is a key enzyme in the degradation of PVA, suggesting that OPH has a great potential for application in textile desizing processes. In this study, the OPH gene from Sphingopyxis sp. 113P3 was modified, by artificial synthesis, for overexpression in Escherichia coli. The OPH gene, lacking the sequence encoding the original signal peptide, was inserted into pET-20b (+) expression vector, which was then used to transform E. coli BL21 (DE3). OPH expression was detected in culture medium in which the transformed E. coli BL21 (DE3) was grown. Nutritional and environmental conditions were investigated for improved production of OPH protein by the recombinant strain. The highest OPH activity measured was 47.54 U/mL and was reached after 84 h under optimal fermentation conditions; this level is 2.64-fold higher that obtained under sub-optimal conditions. The productivity of recombinant OPH reached 565.95 U/L/h. The effect of glycine on the secretion of recombinant OPH was examined by adding glycine to the culture medium to a final concentration of 200 mM. This concentration of glycine reduced the fermentation time by 24 h and increased the productivity of recombinant OPH to 733.17 U/L/h. Our results suggest that the recombinant strain reported here has great potential for use in industrial applications.
Exploring the Role of Religiosity and Spirituality in Amniocentesis Decision‐Making Among Latinas
Authors: Seth Sarah Guerra , Goka Thomas , Harbison Andrea , Hollier Lisa , Peterson Susan , Ramondetta Lois , Noblin Sarah Jane 
Published: June 2011

AbstractGiven the complex array of emotional and medical issues that may arise when making a decision about amniocentesis, women may find that their spiritual and/or religious beliefs can comfort and assist their decision‐making process. Prior research has suggested that Latinas’ spiritual and/or religious beliefs directly influence their amniocentesis decision. A more intimate look into whether Latinas utilize their beliefs during amniocentesis decision‐making may provide an opportunity to better understand their experience. The overall goal of this study was to describe the role structured religion and spirituality plays in Latinas’ daily lives and to evaluate how religiosity and spirituality influences health care decisions, specifically in prenatal diagnosis. Semi‐structured interviews were conducted with eleven women who were invited to describe their religious beliefs and thoughts while considering the option of amniocentesis. All participants acknowledged the influence of religious and/or spiritual beliefs in their everyday lives. Although the women sought comfort and found validation in their beliefs and in their faith in God's will during their amniocentesis decision‐making process, results suggest the risk of procedure‐related complications played more of a concrete role than their beliefs.